PREAMBLE (NOT PART OF THE STANDARD)

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END OF PREAMBLE (NOT PART OF THE STANDARD)

EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄlSCHE NORM

EN 1997-2

March 2007

ICS 91.060.01; 91.120.20

Supersedes ENV 1997-2:1999, ENV 1997-3:1999
Incorporating corrigendum June 2010

English Version

Eurocode 7 - Geotechnical design - Part 2: Ground investigation and testing

Eurocode 7 - Calcul géotechnique - Partie 2: Reconnaissance des terrains et essais Eurocode 7 - Entwurf, Berechnung und Bemessung in der Geotechnik - Teil 2: Erkundung und Untersuchung des Baugrunds

This European Standard was approved by CEN on 12 June 2006.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

Image

Management Centre: rue de Stassart, 36 B-1050 Brussels

© 2007 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members.

Ref. No. EN 1997-2:2007: E

1

Contents

Page
Foreword 7
Section 1 General 10
  1.1 Scope 10
    1.1.1 Scope of Eurocode 7 10
    1.1.2 Scope of EN 1997-2 10
  1.2 Normative references 11
  1.3 Assumptions 12
  1.4 Distinction between Principles and Application Rules 12
  1.5 Definitions 13
    1.5.1 Terms common to all Eurocodes 13
    1.5.2 Terms common to Eurocode 7 13
    1.5.3 Specific definitions used in EN 1997-2 13
  1.6 Test results and derived values 14
  1.7 The link between EN 1997-1 and EN 1997-2 15
  1.8 Symbols and Units 16
Section 2 Planning of ground investigations 20
  2.1 Objectives 20
    2.1.1 General 20
    2.1.2 Ground 21
    2.1.3 Construction materials 22
    2.1.4 Groundwater 22
  2.2 Sequence of ground investigations 22
  2.3 Preliminary investigations 23
  2.4 Design investigations 24
    2.4.1 Field investigations 24
    2.4.2 Laboratory tests 27
  2.5 Controlling and monitoring 31
Section 3 Soil and rock sampling and groundwater measurements 33
  3.1 General 33
  3.2 Sampling by drilling 33
  3.3 Sampling by excavation 33
  3.4 Soil sarnnling 33
    3.4.1 Categories of sampling methods and laboratory quality classes of samples 33
    3.4.2 Soil identification 34
    3.4.3 Planning of soil sampling 34
    3.4.4 Handling, transport and storing of samples 35
  3.5 Rock sampling 35
    3.5.1 Categories of sampling methods 35
    3.5.2 Rock identification 36
    3.5.3 Planning of rock sampling 36
    3.5.4 Handling, transport and storing of samples 37
  3.6 Groundwater measurements in soils and rocks 37
    3.6.1 General 37
    3.6.2 Planning and execution of the measurements 37
    3.6.3 Evaluation of results of groundwater measurements 38 2
Section 4 Field tests in soil and rock 40
  4.1 General 40
  4.2 General requirments 40
    4.2.1 Planning a specific test programme 40
    4.2.2 Execution 41
    4.2.3 Evaluation 41
  4.3 Cone penetration and piezocone penetration tests (CPT, CPTU, CPTM) 42
    4.3.1 Objectives 42
    4.3.2 Specific requirements 42
    4.3.3 Evalutation of test results 43
    4.3.4 Use of test results and derived values 43
  4.4 Pressuremeter test (PMT) 45
    4.4.1 Objectives 45
    4.4.2 Specific requirements 45
    4.4.3 Evaluation of test results 46
    4.4.4 Use of test results and derived values 47
  4.5 Flexible dilatometer test (FDT) 48
    4.5.1 Objectives 48
    4.5.2 Specfic requirements 48
    4.5.3 Evaluation of test results 48
    4.5.4 Use of test results and derived values 49
  4.6 Standard penetration test (SPT) 49
    4.6.1 Objectives 49
    4.6.2 Specific requirements 49
    4.6.3 Evaluation of test results 49
    4.6.4 Use of test results and derived values 50
  4.7 Dvnamic Drobing tests (DP) 51
    4.7.1 Objectives 51
    4.7.2 Specific requirements 52
    4.7.3 Evaluation of test results 52
    4.7.4 Use of test results and derived values 52
  4.8 Weight sounding test (WST) 53
    4.8.1 Objectives 53
    4.8.2 Specific requirements 53
    4.8.3 Evaluation of test results 54
    4.8.4 Use of test results and derived values 54
  4.9 Field vane test (FVT) 55
    4.9.1 Objectives 55
    4.9.2 Specific requirements 55
    4.9.3 Evaluation of test results 55
    4.9.4 Use of test results and derived values 55
  4.10 Flat dilatometer test (DMT) 56
    4.10.1 Objectives 56
    4.10.2 Specific requirements 56
    4.10.3 Evaluation of test results 56
    4.10.4 Use of test results and derived values 57
  4.11 Plate loading test (PLT) 57
    4.11.1 Objectives 57
    4.11.2 Specific requirements 58
    4.11.3 Evaluation of test results 58
    4.11.4 Use of test results and derived values 58 3
Section 5 Laboratory tests on soil and rock 60
  5.1 General 60
  5.2 General requirements for laboratory tests 60
    5.2.1 General requirements 60
    5.2.2 Procedures, equipment and presentation 60
    5.2.3 Evaluation of test results 60
  5.3 Preparation of soil specimens for testing 61
    5.3.1 Objective 61
    5.3.2 Requirements 61
  5.4 Preparation of rock specimens for testing 62
    5.4.1 Obejective 62
    5.4.2 Requirements 62
  5.5 Tests for classification, identification and description of soil 63
    5.5.1 General 63
    5.5.2 Requirements for all classification tests 63
    5.5.3 Water content determination 63
    5.5.4 Bulk density determination 64
    5.5.5 Particle density determination 64
    5.5.6 Particle size analysis 64
    5.5.7 Consistency limits determination 65
    5.5.8 Determination of the density index of granular soil 66
    5.5.9 Soil dispersibility determination 67
    5.5.10 Frost susceptibility 68
  5.6 Chemical testing of soil and groundwater 68
    5.6.1 Requirements for all chemical tests 68
    5.6.2 Organic content determination 70
    5.6.3 Carbonate content determination 71
    5.6.4 Sulfate content determination 71
    5.6.5 pH value determination (acidity and alkalinity) 72
    5.6.6 Chloride content determination 72
  5.7 Strength index testing of soil 73
    5.7.1 Objective 73
    5.7.2 Requirements 73
    5.7.3 Use of test results 73
  5.8 Strength testing of soil 73
    5.8.1 Objective and scope 73
    5.8.2 General requirements 74
    5.8.3 Evaluation and use of test results 75
    5.8.4 Unconfined compression test 75
    5.8.5 Unconsolidated, undrained triaxial compression test 76
    5.8.6 Consolidated triaxial compression test 76
    5.8.7 Consolidated direct shear box tests 77
  5.9 Compressibility and deformation testing of soil 78
    5.9.1 General 78
    5.9.2 Oedometer compressibility testing 78
    5.9.3 Triaxial deformability testing 80
  5.10 Compaction testing of soil 81
    5.10.1 Scope 81
    5.10.2 Compaction tests 81
    5.10.3 California Bearing ratio (CBR) test 81 4
  5.11 Permeability testing of soil 82
    5.11.1 Objective 82
    5.11.2 Requirements 82
    5.11.3 Evaluation and use of test results 83
  5.12 Tests for classification of rocks 84
    5.12.1 General 84
    5.12.2 Requirements for all classification tests 84
    5.12.3 Rock identification and description 84
    5.12.4 Water content determination 85
    5.12.5 Density and porosity determination 86
  5.13 Swelling testing of rock material 86
    5.13.1 General 86
    5.13.2 General requirements 87
    5.13.3 Evaluation of test results 87
    5.13.4 Swelling pressure index under zero volume change 87
    5.13.5 Swelling strain index for radially-confined specimens with axial surcharge 88
    5.13.6 Swelling strain developed in unconfined rock specimen 89
  5.14 Strength testing of rock material 89
    5.14.1 General 89
    5.14.2 Requirements for all strength tests 89
    5.14.3 Evaluation of test results 90
    5.14.4 Uniaxial compression and deformability test 90
    5.14.5 Point load test 91
    5.14.6 Direct shear test 92
    5.14.7 Brazil test 93
    5.14.8 Triaxial compression test 94
Section 6 Ground investigation report 95
  6.1 General requirements 95
  6.2 Presentation of geotechnical information 95
  6.3 Evaluation of geotechnical information 96
  6.4 Establishment of Heri ved values 97
Annex A (informative) List of test results of geotechnical test standards 98
Annex B (informative) Planning of geotechnical investigations 101
Annex C (informative) Example of groundwater pressure derivations based on a model and long term measurements 109
Annex D (informative) Cone and piezocone penetration tests 111
Annex E (informative) Pressure meter test 121
Annex F (informative) Standard penetration test 125
Annex G (informative) Dynamic probing test 129
Annex H (informative) Weight sounding test 132
Annex I (informative) Field vane test 133
Annex j (informative) Flat dilatometer test Example of correlations between EOED and DMT results 138
Annex K (informative) Plate loading test 139
Annex L (informative) Detailed information on preparation of soil specimens for testing 143
Annex M (informative) Detailed information on tests for classification, identification and descrintion of soil 150
Annex N (informative) Detailed information on chemical testing of soil 157 5
Annex O (informative) Detailed information on strength index testing of soil 162
Annex P (informative) Detailed information on strength testing of soil 163
Annex Q (informative) Detailed information on compressibility testing of soil 65
Annex R (informative) Detailed information on compaction testing of soil 166
Annex S (informative) Detailed information on permeability testing of soil 168
Annex T (informative) Preparation of specimen for testing on rockmaterial 170
Annex U (informative) Classification testing of rock material 171
Annex V (informative) Swelling testing of rock material 173
Annex W (informative) Strength testing of rock material 175
Annex X (informative) Bibliography 180
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Foreword

This document (EN 1997-2: 2007) has been prepared by Technical Committee CEN/TC 250 “Structural Eurocodes”, the secretariat of which is held by BSI.

This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by September 2007, and conflicting national standards shall be withdrawn at the latest by March 2010.

This document supersedes ENV 1997-2:1999 and ENV 1997-3:1999.

CEN/TC 250 is responsible for all Structural Eurocodes.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Portugal, Poland, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.

Background of the Eurocode programme

In 1975, the Commission of the European Community decided on an action programme in the field of construction, based on article 95 of the Treaty. The objective of the programme was the elimination of technical obstacles to trade and the harmonization of technical specifications.

Within this action programme, the Commission took the initiative to establish a set of harmonised technical rules for the design of construction works, which, in a first stage, would serve as an alternative to the national rules in force in the Member States and, ultimately, would replace them.

For fifteen years, the Commission, with the help of a Steering Committee with representatives of Member States, conducted the development of the Eurocodes programme, which led to the first generation of European codes in the 1980s.

In 1989, the Commission and the Member States of the EU and EFTA decided, on the basis of an agreement1 between the Commission and CEN, to transfer the preparation and the publication of the Eurocodes to CEN through a series of Mandates, in order to provide them with a future status of European Standard (EN). This links de facto the Eurocodes with the provisions of all the Council’s Directives and/or Commission’s Decisions dealing with European standards (e.g. the Council Directive 89/106/EEC on construction products - CPD - and Council Directives 93/37/EEC, 92/50/EEC and 89/440/EEC on public works and services and equivalent EFTA Directives initiated in pursuit of setting up the internal market).

The Structural Eurocode programme comprises the following standards generally consisting of a number of Parts:

1 Agreement between the Commission of the European Communities and the European Committee for Standardization (CEN) concerning the work on EUROCODES for the design of building and civil engineering works (BC7CEN/03/89).

EN 1990 Eurocode : Basis of Structural Design
EN 1991 Eurocode 1: Actions on structures 7
EN 1992 Eurocode 2: Design of concrete structures
EN 1993 Eurocode 3: Design of steel structures
EN 1994 Eurocode 4: Design of composite steel and concrete structures
EN 1995 Eurocode 5: Design of timber structures
EN 1996 Eurocode 6: Design of masonry structures
EN 1997 Eurocode 7: Geotechnical design
EN 1998 Eurocode 8: Design of structures for earthquake resistance
EN 1999 Eurocode 9: Design of aluminium structures

Eurocode standards recognise the responsibility of regulatory authorities in each Member State and have safeguarded their right to determine values related to regulatory safety matters at national level where these continue to vary from State to State.

Status and field of application of Eurocodes

The Member States of the EU and EFTA recognise that Eurocodes serve as reference documents for the following purposes:

The Eurocodes, as far as they concern the construction works themselves, have a direct relationship with the Interpretative Documents2 referred to in Article 12 of the CPD, although they are of a different nature from harmonised product standards3. Therefore, technical aspects arising from the Eurocodes work need to be adequately considered by CEN Technical Committees and/or EOTA Working Groups working on product standards with a view to achieving full compatibility of these technical specifications with the Eurocodes.

The Eurocode standards provide common structural design rules for everyday use for the design of whole structures and component products of both a traditional and an innovative nature. Unusual forms of construction or design conditions are not specifically covered and additional expert consideration will be required by the designer in such cases.

2 According to An. 3.3 of the CPD. the essential requirements (ERs) shall be given concrete form in interpretative documents for the creation of the necessary links between the essential requirements and the mandates for harmonised ENs and ETAGs/ETAs.

3 According to Art. 12 of the CPD the interpretative documents shall :

  1. give concrete form to the essential requirements by harmonising the terminology and the technical bases and indicating classes or levels for each requirement where necessary ;
  2. indicate methods of correlating these classes or levels of requirement with the technical specifications, e.g. methods of calculation and of proof, technical rules for project design, etc. ;
  3. serve as a reference for the establishment of harmonised standards and guidelines for European technical approvals.

The Eurocodes, de facto, play a similar role in the field of the ER 1 and a part of ER 2.

8

National Standards implementing Eurocodes

The National Standards implementing Eurocodes will comprise the full text of the Eurocode (including any annexes), as published by CEN, which may be preceded by a National title page and National foreword, and may be followed by a National annex.

The National annex may only contain information on those parameters, which are left open in the Eurocode for national choice, known as Nationally Determined Parameters, to be used for the design of buildings and civil engineering works to be constructed in the country concerned, i.e.:

It may also contain:

Links between Eurocodes and harmonised technical specifications (ENs and ETAs) for products

There is a need for consistency between the harmonised technical specifications for construction products and the technical rules for works4. Furthermore, all the information accompanying the CE Marking of the construction products, which refer to Eurocodes, should clearly mention which Nationally Determined Parameters have been taken into account.

Additional information specific to Eurocode 7

EN 1997-2 gives guidance for the planning and interpretation of geotechnical laboratory and field tests that are used for the support of geotechnical design of buildings and civil engineering works.

EN 1997-2 is intended for clients, designers, geotechnical laboratories, field testing laboratories and public authorities.

EN 1997-2 is intended to be used with EN 1997-1.

When using EN 1997-2, particular regard should be paid to the underlying assumptions and conditions given in 1.3.

The six sections of EN 1997-2 are complemented by 24 informative annexes.

National annex for EN 1997-2

The national standard implementing EN 1997-2 should have a national annex containing all information concerning the application of EN 1997-2 in the relevant country.

4 See Art.3.3 and Art.12 of the CPD, as well as 4.2, 4.3.1, 4.3.2 and 5.2 of ID 1.

9

Section 1 General

1.1 Scope

1.1.1 Scope of Eurocode 7

  1. EN 1997 is intended to be used in conjunction with EN 1990:2002, which establishes the principles and requirements for safety and serviceability, describes the basis of design and verification and gives guidelines for related aspects of structural reliability.
  2. EN 1997 is intended to be applied to the geotechnical aspects of the design of buildings and civil engineering works. It is subdivided into various separate parts (see 1.1.2).
  3. EN 1997 is concerned with the requirements for strength, stability, serviceability and durability of structures. Other requirements, e.g. concerning thermal or sound insulation, are not considered.
  4. Numerical values of actions on buildings and civil engineering works to be taken into account in design are provided in EN 1991 for the various types of construction. Actions imposed by the ground, such as earth pressures, shall be calculated according to the rules of EN 1997.
  5. Separate European Standards are intended to be used to treat matters of execution and workmanship. They are denoted in the relevant sections.
  6. In EN 1997 execution is covered to the extent that is necessary to conform to the assumptions of the design rules.
  7. EN 1997 does not cover the special requirements of seismic design. EN 1998 provides additional rules for geotechnical seismic design, which complete or adapt the rules of this standard.

1.1.2 Scope of EN 1997-2

  1. EN 1997-2 is intended to be used in conjunction with EN 1997-1 and provides rules supplementary to EN 1997-1 related to:

    In addition, examples of the application of field test results to design are given.

    NOTE Establishment of characteristic values is covered in EN 1997-1.

  2. This document gives no specific provisions for environmental ground investigations.
  3. Only commonly used geotechnical laboratory and field tests are covered in this standard. These were selected on the basis of their importance in geotechnical practice, availability in 10 commercial geotechnical laboratories and existence of an accepted testing procedure in Europe. The laboratory tests on soils are mainly applicable to saturated soils.

    NOTE It is expected that updates of the present standard will gradually include laboratory and field tests covering additional aspects of soil and rock behaviour.

  4. The provisions of this standard apply primarily to projects of geotechnical category 2, as defined in 2.1 of EN 1997-1:2004. The ground investigation requirements for category 1 projects are normally limited as the verifications often will be based on local experience. For geotechnical category 3 projects, the amount of investigations required will normally be at least the same as indicated for geotechnical category 2 projects in the following sections. Additional investigations and more advanced tests, related to the circumstances that place a project in geotechnical category 3, may be necessary.
  5. The derivation of parameter values is dedicated primarily to the design of pile and spread foundations based on field testing, as detailed in Annexes D, E, F and G of EN 1997-1:2004.

1.2 Normative references

  1. The following normative documents contain provisions which, through reference in this text, constitute provisions of this European Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this European Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the last edition of the normative document referred to applies.
    EN 1990:2002 Eurocode — Basis of structural design
    EN 1997-1:2004 Eurocode 7 — Geotechnical design — Part 1: General rules
    EN ISO 14688-1 Geotechnical investigation and testing — Identification and classification of soil — Part 1: Identification and description
    EN ISO 14688-2 Geotechnical investigation and testing — Identification and classification of soil — Part 2: Classification principles
    EN ISO 14689-1 Geotechnical investigation and testing — Identification and classification of rock - Part 1: Identification and description
    EN IS0 22475-15 Geotechnical investigation and testing — Sampling by drilling and excavation and groundwater measurements — Part 1: Technical principles of execution
    Image EN ISO 22476-15 Geotechnical investigation and testing — Field testing — Part 1: Electrical cone and piezocone penetration tests Image
    EN ISO 22476-2 Geotechnical investigation and testing — Field testing probing — Part 2: Dynamic probing
    EN ISO 22476-3 Geotechnical investigation and testing — Field testing — Part 3: Standard penetration test
    EN ISO 22476-45 Geotechnical investigation and testing — Field testing — Part 4: Ménard pressuremeter test
    EN ISO 22476-55 Geotechnical investigation and testing — Field testing — Part 5: dilatometer test
    EN ISO 22476-66 Geotechnical investigation and testing — Field testing — Part 6: boring pressuremeter test
    Image EN ISO 22476-76 Geotechnical investigation and testing — Field testing — Part 7: Borehole jack test Image11
    EN ISO 22476-86 Geotechnical investigation and testing — Field testing — Part 8: Full displacement pressuremeter test
    EN ISO 22476-96 Geotechnical investigation and testing — Field testing — Part 9: Field vane test
    Image EN ISO 22476-12 Geotechnical investigation and testing — Field testing — Part 12: Mechanical CPT Image
    EN ISO 22476-136 Geotechnical investigation and testing — Field testing — Part 13: Plate loading test

    5 to be published

    Image 6 to be published Image

    NOTE The Bibliography presents a number of CEN ISO Technical Specifications (CEN ISO/TS), giving information on procedures, equipment, evaluation and presentation for some field and laboratory tests. These technical specifications may become European/ISO standards in due time. The National Standards Body may decide to keep its national standard in force during the lifetime of a CEN ISO/TS. National Annexes to EN 1997-2 may give information regarding national practise involved.

1.3 Assumptions

  1. Reference is made to - EN 1990:2002, 1.3 and EN 1997-1:2004, 1.3.
  2. The provisions of this standard are based on the assumptions given below:

1.4 Distinction between Principles and Application Rules

  1. Depending on the character of the individual clauses, distinction is made in EN 1997-2 between Principles and Application Rules.
  2. The Principles comprise:
  3. The Principles are preceded by the letter P.
  4. The Application Rules are examples of generally recognised rules which follow the Principles and satisfy their requirements.
  5. It is permissible to use alternatives to the Application Rules given in this standard, provided it is shown that the alternative rules accord with the relevant Principles and are at least equivalent with regard to the structural safety, serviceability and durability, which would be expected when using the Eurocodes.

    NOTE If an alternative design rule is submitted for an application rule, the resulting design cannot be claimed to be wholly in accordance with EN 1997-2, although the design will remain in accordance with the Principles of EN 1997-1. When EN 1997-2 is used in respect of a property listed in an Annex Z of a product standard or an ETAG, the use of an alternative design rule may not be acceptable for CE marking.

    12
  6. In EN 1997-2, the Application Rules are identified by a number in brackets e.g. as in this clause.

1.5 Definitions

1.5.1 Terms common to all Eurocodes

  1. P The terms used in common for all Eurocodes are defined in EN 1990.

1.5.2 Terms common to Eurocode 7

  1. P The terms specific to EN 1997 are defined in 1.5.2 of EN 1997-1:2004.

1.5.3 Specific definitions used in EN 1997-2

1.5.3.1
derived value

value of a geotechnical parameters obtained from test results by theory, correlation or empiricism (see 1.6)

1.5.3.2
disturbed sample

sample where the soil structure, water content and/or constituents have been changed during sampling

1.5.3.3
measured value

value that is measured in a test

1.5.3.4
natural specimen

specimen made from the available (disturbed, undisturbed, remoulded) sample

1.5.3.5
quality class

classification by which the quality of a soil sample is assessed in the laboratory

NOTE For laboratory testing purposes, soil samples are classified in five quality classes (see 3.4.1).

1.5.3.6
remoulded sample

sample of which the soil or rock structure is fully disturbed

1.5.3.7
remoulded specimen

fully disturbed specimen, at natural water content

13
1.5.3.8
re-compacted specimen

specimen forced into a mould with a rammer or under desired static stress state

1.5.3.9
reconstituted specimen

specimen prepared in the laboratory; for fine soils, it is prepared as a slurry (at or above the liquid limit) and then consolidated (sedimented); for coarse soils, it is either poured or pluviated in dry (dried) or wet conditions and compacted, or consolidated

1.5.3.10
re-consolidated specimen

specimen compressed in a mould or cell under static pressure while allowing drainage to take place

1.5.3.11
sample

portion of soil or rock recovered from the ground by sampling techniques

1.5.3.12
specimen

part of a soil or rock sample used for a laboratory test

1.5.3.13
strength index test

test of a nature that yields an indication of the shear strength, without necessarily giving a representative value

NOTE The results of such a test are subject to uncertainty.

1.5.3.14
swelling

expansion due to reduction of effective stress resulting from either reduction of total stress or absorption of (in general) water at constant total stress

NOTE Swelling includes the reverse of both compression and consolidation.

1.5.3.15
undisturbed sample

sample where no change in the soil characteristics of practical significance has occurred

1.6 Test results and derived values

  1. Test results and derived values form the basis for the selection of characteristic values of ground properties to be used for the design of geotechnical structures, in accordance with 2.4.3 of EN 1997-1:2004.

    NOTE 1 The process of geotechnical design consists of a few successive phases (see Figure 1.1), the first of which covers the site investigation and testing, whereas the next one is devoted to the determination of characteristic values, and the last phase covers the design verification calculations. Rules for the first phase are given in the

    14

    present standard. The determination of characteristic values and the design of the structures are covered by EN 1997-1.

    Figure 1.1 — General framework for the selection of derived values of geotechnical properties

    Figure 1.1 — General framework for the selection of derived values of geotechnical properties

  2. Image Test results can be experimental curves or values of geotechnical parameters. In Annex A, a list of test results is given to serve as a reference to test standards7. Image
  3. Derived values of geotechnical parameters and/or coefficients, are obtained from test results by theory, correlation or empiricism.

    NOTE 2 The examples of correlations used to determine derived values given in the annexes to Section 4 of this standard are obtained from the literature. These correlations may correlate the value of a geotechnical parameter or coefficient with a test result, such as the qc-value of a CPT. They may also connect a geotechnical parameter to a test result by means of theoretical considerations (for example, when deriving a value of the angle of shearing resistance φ′ from pressuremeter test results or from the index of plasticity).

    NOTE 3 In certain cases, the derivation of geotechnical parameters by means of a correlation is not made before the determination of the characteristic value, but after the test results have been corrected or transformed into conservative estimates.

1.7 The link between EN 1997-1 and EN 1997-2

  1. Figure 1.2 presents the general architecture of the CEN standards related to geotechnical engineering problems and those directly linked to EN 1997. The design part is covered by EN 1997-1. The present standard gives rules for ground investigations and obtaining geotechnical parameters or coefficients values to be used for determining the characteristic values (as specified in EN 1997-1). It gives also informative examples of calculation methods for spread and deep foundations. The implementation of EN 1997 needs information based on other standards, in particular those related to ground investigations and to the execution of geotechnical works.

7 Geotechnical test standards, yielding these results are prepared by CEN/TC341.

15

EN 1997-1

Design rules
  • – General framework for geotechnical design
  • – Definition of ground parameters
  • – Characteristic and design values
  • – General rules for site investigation
  • – Rules for the design of main types of geotechnical structures
  • – Some assumptions on execution procedures

EN 1997-2

Geotechnical investigation and testing
  • – Detailed rules for site investigations
  • – General test specifications
  • – Derivation of ground properties and geotechnical model of the site
  • – Examples of calculation methods based on field and laboratory tests

Test standards (CEN/TC 341)

Standards for
  • – Drilling and sampling methods and groundwater measurements
  • – Laboratory and field tests on soils and rocks
  • – Tests on structures or parts of structures
  • – Identification and classification of soils and rocks

Execution of geotechnical works (CEN/TC 288)

Execution standards
  • – specific design rules (informative annexes)
  • – specific test procedures

Figure 1.2 — General architecture of the CEN standards linked with EN 1997

1.8 Symbols and units

  1. For the purpose of EN 1997-2 the following symbols apply.

    NOTE The notation of the symbols used is based on ISO 3898:1997.

    Latin letters

    Cc compression index
    c′ cohesion intercept in terms of effective stress
    cfv undrained shear strength from the field vane test
    cu undrained shear strength
    Cs swelling index
    cv coefficient of consolidation
    Cα coefficient of secondary compression
    Dn particle size such that n % of the particles by weight are smaller than that size e.g. D10, D15, Dm, D60 and D85 16
    E Young’s modulus of elasticity
    E′ drained (long term) Young’s modulus of elasticity
    EFDT flexible dilatometer modulus
    EM Ménard pressuremeter modulus
    Emeas measured energy during calibration
    Eoed oedometer modulus
    EPLT modulus from plate loading test
    Er energy ratio (= Emeas/ Etheor)
    Etheor theoretical energy
    Eu undrained Young’s modulus of elasticity
    E0 initial Young’s modulus of elasticity
    E50 Young’s modulus of elasticity corresponding to 50 % of the maximum shear strength
    IA activity index
    IC consistency index
    ID density index
    IDMT material index from the flat dilatometer test
    KDMT horizontal stress index from the flat dilatometer test
    Image k coefficient of permeability Image
    IL liquidity index
    IP plasticity index
    ks coefficient of sub-grade reaction
    mv coefficient of compressibility
    N number of blows per 300 mm penetration from the SPT
    Nk cone factor for CPT, (see equation (4.1))
    Nkt cone factor for CPTU, (see equation (4.2))
    N10L number of blows per 10 cm penetration from the DPL
    N10M number of blows per 10 cm penetration from the DPM
    N10H number of blows per 10 cm penetration from the DPH
    N10SA number of blows per 10 cm penetration from the DPSH-A
    N10SB number of blows per 10 cm penetration from the DPSH-B
    N20SA number of blows per 20 cm penetration from the DPSH-A
    N20SB number of blows per 20 cm penetration from the DPSH-B
    N60 number of blows from the SPT corrected to energy losses
    (N1)60 number of blows from the SPT corrected to energy losses and normalized for effective vertical overburden stress 17
    pLm Méenard limit pressure
    qc cone penetration resistance
    qt cone penetration resistance corrected for pore water pressure effects
    qu unconfined compressive strength
    Wopt optimum water content

    Greek letters

    Image α correlation factor for Eoed and qc, (see Equation (4.3)) Image
    φ angle of shearing resistance
    φ′ angle of shearing resistance in terms of effective stress
    μ correction factor to derive cu from cfv, (see Equation (4.4))
    ρd;max maximum dry density
    σC unconfined compression strength of rock
    Image σ′p effective pre-consolidation pressure or effective vertical yield stress in situ Image
    σT tensile strength of rock
    Image σv0 initial vertical total stress Image
    Image σ′vo initial vertical effective stress Image
    v Poisson’s ratio

    Abbreviations

    ImageCPT electrical cone penetration test Image
    Image CPTM mechanical cone penetration test Image
    CPTU cone penetration test with pore water pressure measurement
    DMT flat dilatometer test
    DP dynamic probing
    DPL dynamic probing light
    DPM dynamic probing medium
    DPH dynamic probing heavy
    DPSH-A dynamic probing superheavy, type A
    DPSH-B dynamic probing superheavy, type B
    FDP full displacement pressuremeter
    FDT flexible dilatometer test
    FVT field vane test
    MPM Ménard pressuremeter 18
    PBP pre-bored pressuremeter
    PLT plate loading test
    PMT pressuremeter test
    RDT rock dilatometer test
    SBP self-boring pressuremeter
    SDT soil dilatometer test
    SPT standard penetration test
    WST weight sounding test
  2. For geotechnical calculations, the following units or their multiples are recommended:
    force kN
    moment kNm
    mass density kg/m3
    weight density kN/m3
    stress, pressure, strength and stiffness kPa
    coefficient of permeability m/s
    coefficient of consolidation m2/s
19

Section 2 Planning of ground investigations

2.1 Objectives

2.1.1 General

  1. P Geotechnical investigations shall be planned in such a way as to ensure that relevant geotechnical information and data are available at the various stages of the project. Geotechnical information shall be adequate to manage identified and anticipated project risks. For intermediate and final building stages, information and data shall be provided to cover risks of accidents, delays and damage.
  2. The aims of a geotechnical investigation are to establish the soil, rock and groundwater conditions, to determine the properties of the soil and rock, and to gather additional relevant knowledge about the site.
  3. P Careful collection, recording and interpretation of geotechnical information shall be made. This information shall include ground conditions, geology, geomorphology, seismicity and hydrology, as relevant. Indications of the variability of the ground shall be taken into account.
  4. Ground conditions which may influence the choice of geotechnical category should be determined as early as possible in the investigation.

    NOTE As a result of the geotechnical investigations, it may be necessary to change the geotechnical category of the project (see 1.1.2 (4)).

  5. Geotechnical investigations should consist of ground investigations, and other investigations for the site, such as:
  6. Before designing the investigation programme, the available information and documents should be evaluated in a desk study.
  7. Examples of information and documents that can be used are:
  8. Ground investigations should consist of field investigations, laboratory testing, additional desk studies and controlling and monitoring, where appropriate.
  9. P Before the investigation programme has been drawn up the site shall be visually examined and the findings recorded and cross-checked against the information gathered by desk studies.
  10. The ground investigation programme should be reviewed as the results become available so that the initial assumptions can be checked. In particular:
  11. Special attention should be paid to sites that have been previously used, where disturbance of the natural ground conditions may have taken place.
  12. P An appropriate quality assurance system shall be in place in the laboratory, in the field and in the engineering office, and quality control shall be exercised competently in all phases of the investigations and their evaluation.

2.1.2 Ground

  1. P Ground investigations shall provide a description of ground conditions relevant to the proposed works and establish a basis for the assessment of the geotechnical parameters relevant for all construction stages.
  2. The information obtained should enable assessment of the following aspects, if possible:
21

2.1.3 Construction materials

  1. P Geotechnical investigations of soil and rock for use as construction materials shall provide a description of the materials to be used and shall establish their relevant parameters.
  2. The information obtained should enable an assessment of the following aspects:

2.1.4 Groundwater

  1. P Groundwater investigations shall provide all relevant information on groundwater needed for geotechnical design and construction.
  2. Groundwater investigations should provide, when appropriate, information on:
  3. The information obtained should be sufficient to assess the following aspects, where relevant:

2.2 Sequence of ground investigations

  1. P The composition and the extent of the ground investigations shall be based on the anticipated type and design of the construction, e.g. type of foundation, improvement method or retaining structure, location and depth of the construction; 22
  2. P The results of the desk studies and the site inspection shall be considered when selecting the investigation methods and locating the various investigation points. Investigations shall be targeted at points representing the variation in ground conditions for soil, rock and groundwater.
  3. Ground investigations should normally be performed in phases depending on the questions raised during planning, design and construction of the actual project. The following phases are treated separately in Section 2:

    NOTE The provisions in this document are based on the premise that the results from investigations recommended in one phase are available before the next phase is started.

  4. In cases where all investigations are performed at the same time, 2.3 and 2.4 should be considered simultaneously.

    NOTE The different stages of ground investigations, including laboratory and field work and the process of evaluating soil and rock parameters, can follow the schemes in B.1 and B.2.

2.3 Preliminary investigations

  1. The preliminary investigations should be planned in such a way that adequate data are obtained, if relevant, to:
  2. A preliminary ground investigation should supply estimates of soil data concerning, if relevant:
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2.4 Design investigations

2.4.1 Field investigations

2.4.1.1 General
  1. P In cases where the preliminary investigations do not provide the necessary information to assess the aspects mentioned in 2.3, complementary investigations shall be performed during the design investigation phase.
  2. If relevant, field investigations in the design phase should comprise:
  3. Examples of the various types of field investigations are:
  4. To develop strategies for planning field investigations, Table 2.1 can be used as a guide to the applicability of the field investigations covered in Sections 3 and 4.

    NOTE See also B.2.

  5. P Where ground contamination or soil gas is expected, information shall be gathered from the relevant sources. This information shall be taken into account when planning the ground investigation. 24
    Table 2.1 — Simplified overview of the applicability of field investigation methods a) covered by Sections 3 and 4
    Field investigation methods a) Possibly obtabinable results
    Sampling Field tests Groundwater measurements
    Soil Rock CPT & CPTU Pressuremeter c) Flexible SPTd) DPL/DPM DPH/DPSH WST FVT DMT DLT Open system Closed system
    Category A Category B Category C Category A Category B Category C RDT Dilatometer
    Basic information                                      
    Type of soil C1 F1 C1 F1 C2 F2 C2 F2 C3 F3 C3 F3 C2 F1 C3 F3 C3 F3 C2 F2
    Type of rock R1 R1 R2 R3e) R3 R2  
    Extension of layeresb) C1 F1 C1 F1 C3 F3 R1 R1 R2 C1 F1 R3 C3 F3 R3 C3 F3 C2 F2 C1 F2 C1 F2 F2 C2 F1
    Groundwater level C2 R2 C1 F2 R1 C1 F1
    Pore water pressure C2 F2 F3 R2 C1 F2 R1 C1 F1
    Geotechnical properties  
    Pariticle size C1 F1 C1 F1   R1 R1 R2 C2 F1
    Water content C1 F1 C2 F1 C3 F3 R1 R1 C2 F2
    Atterberg limits F1 F1 F2
    Density C2 F1 C3 F3 R1 R1 C2 F2 C2 F2 C2 C2 C2 F2
    Shear strength C2 F1 R1 C2 F1 C1 F1 C2 F3 C2 F3 C2 F3 C2 F1 C2 F1 R2 C1 F1
    Compressibility C2 F1 R1 C1 F2 C1 F1 R1 F1 C2 F2 C2 F2 C2 F2 C2 C2 F1 C1 F1
    Permeability C2 F1 R1 C3 F2 F3 C2 F3 C2 F2
    Chemical test C1 F1 C1 F1 R1 R1 C2 F2
    1. see section 3 and 4 for nomenclature
    2. in horizontal and vertical direction
    3. will depend on pressuremeter type
    4. assuming sample is retained
    5. soft rock only
    R1 High for rock       R2 Medium for rock       R3 Low for rock
    C1 High for coarse soil*)       C2 Medium for coarse soil       C3 Low for coarse soil
    F1 High for fine soil*)       F2 Medium for fine soil       F3 Low for find soil
    — not applicable
    Applicability *) main soil groups “coarse” and “fine” according to ISO 14688-1
    Note Depending on the ground conditions (such as soil type, groundwater conditions) and the planned design, the selection of investigation methods will vary and may deviate from this table.
    25
  6. P If ground contamination or soil gas is detected in the course of ground investigations, this shall be reported to the client and the responsible authorities.
2.4.1.2 Field investigation programme
  1. P The field investigation programme shall contain:
2.4.1.3 Locations and depths of the investigation points
  1. P The locations of investigation points and the depths of the investigations shall be selected on the basis of the preliminary investigations as a function of the geological conditions, the dimensions of the structure and the engineering problems involved.
  2. When selecting the locations of investigation points, the following should be observed:
  3. Where ground conditions are relatively uniform or the ground is known to have sufficient strength and stiffness properties, wider spacing or fewer investigation points may be applied. In EITHER case, this choice should be justified by local experience.
  4. P In cases where more than one type of investigation is planned at a certain location (e.g. CPT and piston sampling), the investigation points shall be separated by an appropriate distance. 26
  5. In the case of a combination of, for example, CPTs and boreholes, the CPTs should be carried out prior to the boreholes. The minimum spacing should then be such that the borehole does not or is considered unlikely to encounter the CPT hole. If the drilling is conducted first, the CPT should be carried out at a horizontal separation of at least 2 m.
  6. P The depth of investigations shall be extended to all strata that will affect the project or are affected by the construction. For dams, weirs and excavations below groundwater level, and where dewatering work is involved, the depth of investigation shall also be selected as a function of the hydrogeological conditions. Slopes and steps in the terrain shall be explored to depths below any potential slip surface.

    NOTE For the spacing of investigation points and investigation depths, the values given in B.3 can be used as guidance.

2.4.1.4 Sampling
  1. P The sampling categories (see 3.4.1 and 3.5.1), and the number of samples to be taken shall be based on:
  2. P For identification and classification of the ground, at least one borehole or trial pit with sampling shall be available. Samples shall be obtained from every separate ground layer influencing the behaviour of the structure.
  3. Sampling may be replaced by field tests if there is enough local experience to correlate the field tests with the ground conditions to ensure unambiguous interpretation of the results.
  4. Further details on sampling are given in Section 3.
2.4.1.5 Groundwater
  1. P Groundwater measurements shall be planned and carried out in accordance with 3.6.

2.4.2 Laboratory tests

2.4.2.1 General
  1. Prior to setting up a test programme, the expected stratigraphy at the site should be established and the strata relevant for design selected to enable the specification of the type and number of tests in each stratum. Stratum identification should be a function of the geotechnical problem, its complexity, the local geology and the required parameters for design.
2.4.2.2 Visual inspection and preliminary ground profile
  1. Samples and trial pits should be inspected visually and compared with field logs of the drillings so that the preliminary ground profile can be established. For soil samples, the visual inspection should be supported by simple manual tests to identify the soil and to give a first impression of its consistency and mechanical behaviour.
  2. If distinct and significant differences in the properties between different portions of one stratum are found, the preliminary soil profile should be further subdivided. 27
  3. Where practicable, the quality of the sample should be assessed before laboratory tests are performed. Quality classes for soil samples are defined in Table 3.1.
2.4.2.3 Test programme
  1. P The type of construction, the type of ground and stratigraphy and the geotechnical parameters needed for design calculations shall be taken into account when setting up the laboratory test programme.
  2. The laboratory test programme depends in part on whether comparable experience exists. The extent and quality of comparable experience for the specific soil or rock should be established. The results of field observations on neighbouring structures, when available, should also be used.
  3. P The tests shall be run on specimens representative of the relevant strata. Classification tests shall be used to check whether the samples and test specimens are representative.

    NOTE This can he checked in an iterative way. In a first step, classification tests and strength index tests are performed on as many samples as possible to determine the variability of the index properties of a stratum. In a second step, an assessment of how representative the samples used for the strength and compressibility tests are of the stratum can be checked by comparing the results of the classification and strength index tests for the samples with all results from the classification and strength index tests for the stratum.

  4. The need for more advanced testing or additional site investigation as a function of the geotechnical aspects of the project, soil type, soil variability and computation model should be considered.
2.4.2.4 Number of tests
  1. P The necessary number of specimens to be tested shall be established depending on the homogeneity of the ground, the quality and amount of comparable experience with the ground and the geotechnical category of the problem.
  2. To allow for difficult soil, damaged specimens and other factors, additional test specimens should be made available, whenever possible.
  3. Depending on the test type, a minimum number of specimens should be investigated.

    NOTE A recommended minimum number for some test types can be taken from the tables in Annexes L to W (except Annexes O and T). The annexes can also be used to check whether the extent of the testing was sufficient.

  4. The minimum number of tests may be reduced if the geotechnical design does not need to be optimised and uses conservative values of the soil parameters, or if comparable experience or combination with field information applies.
2.4.2.5 Classification tests
  1. Soil and rock classification tests should be performed to determine the composition and index properties of each stratum. The samples for the classification tests should be selected in such a way that the tests are approximately equally distributed over the complete area and the full depth of the strata relevant for design. Thus the results should give the range of index properties of the relevant layers. 28
  2. The results of the classification tests should be used to check if the extent of the investigations was sufficient or if a second investigation stage is needed.
  3. Suitable routine classification tests for ground samples with various degrees of disturbance are presented in Table 2.2. The routine tests are generally performed in all phases of the ground investigation (see 2.2 (3)).
2.4.3.6 Tests on samples
  1. P Samples for testing shall be selected so as to cover the range of index properties of each relevant stratum.
  2. For a fill or a stratum of sand or gravel, reconstituted specimens may be tested. Reconstituted specimens should have approximately the same composition, density and water content as in-situ material. 29
    Table 2.2 — Soil classification tests
    Parameter Type of soil
    Clayey soil Silty soil Sandy gravelly soil
    Type of specimen Type of specimen Type of specimen
    Undisturbed Disturbed Remoulded Undisturbed Disturbed Remoulded Disturbed Remoulded
    Geological description and soil classification X X X X X X X X
    Water content X (X) (X) X (X) (X) (X) (X)
    Bulk density X (X) X (X)
    Minimum and maximum densities (X) (X) (X) X X
    Atterberg (consistency) limits X X X X X X
    Particle size distribution X X X X X X X X
    Undrained shear strength X (X)
    Permeability X X (X) (X) (X) (X)
    Sensitivity X
    X = normal to determine
    (X) = possible to determine, not necessarily representative
    — = not applicable
    Note For some types of soil, further tests may be considered, for example the determination of organic content, particle density and activity.
  3. Laboratory tests to determine parameters for geotechnical calculations are given in Table 2.3.
  4. Suitable routine laboratory tests for rock samples giving the necessary basis for the description of the rock material are as follows:
  5. The classification of rock core samples will normally comprise a geological description, the core recovery, the Rock Quality Designation (RQD), the degrees of induration, fracture log, weathering and Assuring. In addition to the routine tests mentioned in 2.4.2.6 (4) for rocks, other tests may be selected for different purposes, e.g. density of grains determination, wave velocity determination, Brazilian tests, shear strength of rock and joints determination, slake durability tests, swelling tests and abrasion tests. 30
  6. The properties of the rock mass including the layering and fissuring or discontinuities may be investigated indirectly by compression and shear strength tests along joints. In weak rocks, complementary tests in the field or large-scale laboratory tests on block samples may be made.
    Table 2.3 — Laboratory tests for the determination of geotechnical parameters
    Geotechnical parameter Type of soil
    Gravel Sand Silt NC clay OC clay Peat organic clay
    Oedometer moduls
    (Eoed); compression index (Cc)
    [one-dimensional compressibility]
    (OED)
    (TX)
    (OED)
    (TX)
    (OED)
    (TX)
    (OED)
    (TX)
    (OED)
    (TX)
    (OED)
    (TX)
    Young′ modulus (E);
    Shear modulus(G)
    TX TX TX TX TX TX
    Drained (effective) shear
    strength (c′), (φ′)
    TX
    SB
    TX
    SB
    TX
    SB
    TX
    SB
    TX
    SB
    TX
    SB
    Residual shear strength (cR), (φR) RS
    (SB)
    RS
    (SB)
    RS
    (SB)
    RS
    (SB)
    RS
    (SB)
    RS
    (SB)
    Undrained shear strength(cu) TX
    DSS
    SIT
    TX
    DSS
    (SB)
    SIT
    TX
    DSS
    (SB)
    SIT
    TX
    DSS
    (SB)
    SIT
    Bulk density (ρ) BDD BDD BDD BDD BDD BDD
    Coefficient of
    consolidation (cv)
        OED
    TX
    OED
    TX
    OED
    TX
    OED
    TX
    Permeability (k)
    TXCH
    PSA

    TXCH
    PSA
    PTC
    TXCH
    (PTF)
    PTC
    (PTF)
    (OED)
    PTC
    (PTF)
    (OED)
    PTC
    (PTF)
    (OED)
    — = not applicable
    ( ) = partially applicable only; for details, see Section 5.
    Abbreviations of laboratory tests;
    BDD       Bulk density determination
    DSS       Direct simple shear test
    OED       Oedometer test
    PTF       Permeability test in the falling head permeameter
    PTC       Permeability test in the constant head permeater
    RS       Ring shear (Ring shear box test)
    SB       Translational shear box test
    SIT       Strength index tests (normally performed in the preliminary phase only)
    PSA       Particle size analysis
    TX       Triaxial test
    TXCH       Permeability constant head test in the triaxial cell (or flexible wall permeameter)

2.5 Controlling and monitoring

  1. P A number of checkes and additional tests shall be make during the construction and excution of the project, when relevent, in order to check that the ground conditions agree with 31 those determined in the design investigations and that the properties of the delivered construction materials and the construction works correspond to those presumed or specified.

    NOTE See also EN 1997-1:2004, Section 4.

  2. P The following control measures shall be applied:
  3. The following general control measures may be applied:
  4. P The results of the control measures shall be compiled, reported and checked against the design requirements. Decisions shall be taken based on these findings.
32

Section 3 Soil and rock sampling and groundwater measurements

3.1 General

  1. P Sampling of soils and rocks by drilling and excavations and groundwater measurements shall be conducted so comprehensively that the necessary geotechnical design data are obtained.

3.2 Sampling by drilling

  1. P The drilling equipment shall be selected according to:
  2. P The requirements of EN ISO 22475-1 shall be followed.

3.3 Sampling by excavation

  1. P If samples are recovered from trial pits, headings or shafts, the requirements of EN ISO 22475-1 shall be followed.

3.4 Soil sampling

3.4.1 Categories of sampling methods and laboratory quality classes of samples

  1. P Samples shall contain all the mineral constituents of the strata from which they have been taken. They shall not be contaminated by any material from other strata or from additives used during the sampling procedure.
  2. P Three sampling method categories shall be considered (EN ISO 22475-1), depending on the desired sample quality as follows (for sample quality see Table 3.1):
  3. Samples of quality classes 1 or 2 can only be obtained by using category A sampling methods. The intention is to obtain samples of quality classes 1 or 2, in which no or only slight disturbance of the soil structure has occurred during the sampling procedure or in the handling of the samples. The water content and the void ratio of the soil correspond to those in-situ. No change in constituents or in chemical composition of the soil has occurred. Certain unforeseen circumstances such as variations in geological strata may lead to lower sample quality classes being obtained.
  4. Using category B sampling methods will preclude achieving samples of quality classes better than 3. The intention is to obtain samples that contain all the constituents of the in-situ soil in their original proportions and for the soil to retain its natural water content. The general arrangement of the different soil layers or components can be identified. The structure of the soil has been 33 disturbed. Certain unforeseen circumstances such as variation in geological strata may lead to lower sample quality classes being obtained.
  5. By using category C sampling methods, samples of quality classes better than 5 cannot be obtained. The soil structure in the sample has been totally changed. The general arrangement of the different soil layers or components has been modified so that the in-situ layers cannot be identified accurately. The water content of the sample needs not represent the natural water content of the soil layer sampled.
  6. P Soil samples for laboratory tests are divided in five quality classes with respect to the soil properties that are assumed to remain unchanged during sampling and handling, transport and storage. The classes are described in Table 3.1, together with the sampling category to be used.
    Table 3.1 — Quality classes of soil samples for laboratory testing and sampling categories to be used
    Soil properties / quality class 1 2 3 4 5
    Unchanged soil properties          
    particle size * * * *  
    water content * * *    
    density, density index, permeability * *      
    compressibility, shear strength *        
    Properties that can be determined          
    sequence of layers * * * * *
    boundaries of strata - broad * * * *  
    boundaries of strata - fine * *      
    Atterberg limits, particle density, organic content * * * *  
    water content * * *    
    density, density index, porosity, permeability * *      
    compressibility, shear strength *        
    Sampling category according to EN ISO 22475-1 A
        B
        C

3.4.2 Soil identification

  1. P Soil identification, based on the examination of the samples recovered, shall conform to EN ISO 14688-1.

3.4.3 Planning of soil sampling

  1. P The quality class and number of samples to be recovered shall be based on the aims of the soil investigations, the geology of the site, and the complexity of the geotechnical structure and of the construction to be designed.
  2. Two different strategies may be followed for sampling by drilling.
  3. P The sampling categories shall be selected considering the desired laboratory quality classes, as detailed in Table 3.1, the expected soil types, and groundwater conditions.
  4. P The requirements of EN ISO 22475-1 shall be followed, for the selection of the drilling or excavation methods and sampling equipment adequate to the soil sampling category prescribed.

    NOTE The recovery of completely undisturbed samples is practically impossible due to, among other factors, the mechanical disturbance caused by the sampling operations and to the unavoidable stress release when recovering the sample. The effect of these factors on the degree of disturbance depends on the sampling category used and the types of soil being sampled. The type of soil being sampled has a decisive influence on the degree of disturbance of samples obtained by the same sampling methods. Thus very sensitive soils are prone to disturbance, while less sensitive soils, such as most stiff clays, may require less restrictive methods of sampling for obtaining fairly undisturbed samples. On the other hand, each problem requires a different degree of accuracy for the soil parameters to be used. As a consequence, when preparing a sampling programme, the factors mentioned above should be considered in order to decide the degree of disturbance that can be accepted and therefore the sampling methods to be required.

  5. For a given project, specific sampling equipment and methods may be required within the sampling categories defined in 3.4.1. For instance, this is the case when the deformation moduli (stiffness) at small strains have to be determined in undisturbed samples.
  6. P The dimensions of the samples to be recovered shall be in accordance with the type of soil and the type and number of tests to be performed.

    NOTE See Section 5 and Annexes L, M, N, P, Q, R and S.

  7. Samples should be taken at any change of stratum and at a specified spacing, usually not larger than 3 m. In inhomogeneous soil, or if a detailed definition of the ground conditions is required, continuous sampling by drilling should be carried out or samples recovered at very short intervals.

3.4.4 Handling, transport and storing of samples

  1. P Handling, transport and storing of samples shall be carried out in accordance with EN ISO 22475-1.

    NOTE For handling and storing in the laboratory, see Section 5.

3.5 Rock sampling

3.5.1 Categories of sampling methods

  1. P Samples shall contain all the mineral constituents of the strata from which they have been taken. They shall not be contaminated by any material from other strata or from additives used during the sampling procedure.
  2. P The discontinuities and corresponding infilling materials existing in the rock mass often control the strength and deformation characteristics of the material as a whole. Therefore, they shall be defined as closely as possible during the sampling operations, if such properties have to be determined. 35
  3. P Three sampling method categories shall be considered (see EN ISO 22475-1), depending on the quality of sample:
  4. By using category A sampling methods, the intention is to obtain samples in which no or only slight disturbance of the rock structure has occurred during the sampling procedure or in handling of the samples. The strength and deformation properties, water content, density, porosity and the permeability of the rock sample correspond to the in-situ values. No change in constituents or in chemical composition of the rock mass has occurred. Certain unforeseen circumstances such as variations of the geological strata may lead to lower sample quality being obtained.
  5. By using category B sampling methods, the intention is to obtain samples that contain all the constituents of the in-situ rock mass in their original proportions and with the rock pieces retaining their strength and deformation properties, water content, density and porosity. By using category B sampling methods, the general arrangement of discontinuities in the rock mass can be identified. The structure of the rock mass has been disturbed and thereby the strength and deformation properties, water content, density, porosity and permeability for the rock mass itself. Certain unforeseen circumstances such as variations of the geological strata can lead to lower sample quality being obtained.
  6. Category C sampling methods lead to the structure of the rock mass and its discontinuities being totally changed. The rock material may have been crushed. Some changes in constituents or in chemical composition of the rock material can occur. The rock type and its matrix, texture and fabric can be identified.

3.5.2 Rock identification

  1. P Visual rock identification shall be based on examination of the rock masses and samples including all observations of decomposition and discontinuities. The identification shall conform to EN ISO 14689-1.
  2. P Weathering classification shall be related to the geological processes and shall cover the grades between fresh rock and rock decomposed into soil. The classification shall conform to 4.2.4 and 4.3.4 of EN ISO 14689-1:2003.
  3. P Discontinuities such as bedding planes, joints, fissures, cleavages and faults shall be quantified with respect to pattern, spacing and inclination using unambiguous terms. The quantification shall conform to 4.3.3 of EN ISO 14689-1:2003.
  4. P Rock quality designation (RQD), total core recovery (TCR), and solid core recovery (SCR), as defined by EN ISO 22475-1, shall be determined.

3.5.3 Planning of rock sampling

  1. P The characteristics and number of samples to be recovered shall be based on the aim of the site investigations, the geology of the area and the complexity of the geotechnical structure and of the construction to be designed. 36
  2. P The category of the sampling methods to be prescribed shall be selected according to the rock characteristics to be preserved, as detailed in 3.5.1, and the expected rock and groundwater conditions.
  3. P The requirements of EN ISO 22475-1 shall be followed for the selection of the drilling or excavation methods and sampling equipment.
  4. For a given project, specific sampling equipment and methods may be required within the rock sampling categories defined in 3.5.1.

3.5.4 Handling, transport and storing of samples

  1. P After sampling and visual inspection has taken place, the obtained cores shall be preserved, handled and stored according to EN ISO 22475-1.

3.6 Groundwater measurements in soils and rocks

3.6.1 General

  1. P Groundwater measurements shall conform to 2.1.4.
  2. P The determination of the groundwater table or pore water pressures in soils and rocks shall be made by installing open or closed groundwater measuring systems into the ground.

    NOTE Subclause 3.6 applies to the measurement of positive pore water pressures relative to the atmospheric pressure. Measurements of negative pore water pressures are not considered.

3.6.2 Planning and execution of the measurements

  1. P When relevant, groundwater measurements and sampling shall be conducted in accordance with EN ISO 22475-1.
  2. P The type of equipment to be used for groundwater measurements shall be selected according to the type and permeability of ground, the purpose of the measurements, the required observation time, the expected groundwater fluctuations and the response time of the equipment and ground.
  3. There are two main methods for measuring the groundwater pressure: open systems and closed systems. In open systems the piezometric groundwater head is measured by an observation well, usually provided with an open pipe. In closed systems the groundwater pressure at the selected point is directly measured by a pressure transducer.
  4. Open systems are best suited for soils and rock with a relatively high permeability (aquifers and aquitards), e.g. sand, gravel or highly fissured rock. With soils and rocks of low permeability they may lead to erroneous interpretations, due to the time lag for filling and emptying the pressure pipe. The use of filter tips connected to a small diameter hose in open systems, decreases the time lag.
  5. Closed systems can be used in all types of soil or rock. They should be used in very low permeability soils and rocks (aquicludes), e.g. clay or low fissured rock. Closed systems are also recommended when dealing with high artesian water pressure. 37
  6. P When very short- term variations or fast pore water fluctuations are to be monitored, continuous recording shall be used by means of transducers and data loggers, with any types of soils and rocks.
  7. P In cases where open water is situated within or close to the investigation area, the water level shall be considered in the interpretation of the groundwater measurements. The water level in wells, the occurrence of springs and artesian water shall also be noted.
  8. P The number, location and depth of the measuring stations shall be chosen considering the purpose of the measurements, the topography, the stratigraphy and the soil conditions, especially the permeability of the ground or identified aquifers.
  9. P For monitoring projects e.g. groundwater lowering, excavations, fillings and tunnels, the location shall be chosen with respect to the expected changes to be monitored.
  10. For reference purposes, measurement of the natural fluctuations in groundwater should be made, if possible, outside the area affected by the actual project.
  11. P In order to obtain measurements reflecting the pore pressure at the intended point in a soil or rock layer, provisions shall be made, according to EN ISO 22475-1, to ensure that the measuring point is adequately sealed off with regard to other layers or aquifers.
  12. P The number and frequency of readings and the length of the measuring period for a given project shall be planned considering the purpose of the measurements and the stabilisation period.
  13. The criteria adopted should be adjusted after an initial period of time, according to the actual variations of the readings being observed.
  14. P If it is intended to assess groundwater fluctuations, measurements shall be taken at intervals smaller than the natural fluctuations to be characterised and over a long period of time.
  15. During the drilling process, the observation of the water level at the end of the day and the start of the following day (before the drilling is resumed) is a good indication of the groundwater conditions and should be recorded. Any sudden inflow or loss of water during drilling should also be recorded, since it can provide additional useful information.
  16. During the first phases of site investigations, some of the boreholes may be equipped with open perforated pipes protected with filters. The water level readings obtained during the following days yield a preliminary indication of groundwater conditions, but are subject to the limitations mentioned in 3.6.2 (4). The dangers associated with the connection of different aquifers should be taken into account, as well as any relevant environmental regulations.

3.6.3 Evaluation of results of groundwater measurements

  1. P The evaluation of groundwater measurements shall take into account the geological and geotechnical conditions of the site, the accuracy of individual measurements, the fluctuations of pore water pressures with time, the duration of the observation period, the season of measurements and the climatic conditions during and prior to that period. 38
  2. P The evaluated results of groundwater measurements shall comprise the observed maximum and minimum elevations of the water table, or pore pressures and the corresponding measuring period.
  3. P If applicable, upper and lower bounds for both extreme and normal circumstances shall be derived from the measured values, by adding or subtracting the expected fluctuations or a reduced part of them, to the respective extreme or normal circumstances. The frequent lack of reliable data for extended periods of time of this type of measurements will necessitate the derived values being a cautious estimate based on the limited available information.
  4. The need for making further measurements or installing additional measuring stations should be assessed during the field investigations and in the ground investigation report.

    NOTE In Annex C, an example is presented of a statistical method to evaluate the groundwater conditions, when long term measurements in a reference pipe in the region are available and a short measuring period on the actual site has been carried out.

39

Section 4 Field tests in soil and rock

4.1 General

  1. P When field tests are conducted, they shall be linked to sampling by excavating and drilling, in order to collect information on the ground stratification and to obtain geotechnical parameters or direct input for design methods (see also EN 1997-1:2004, 3.3).
  2. P Field tests shall be planned considering the following general points (see also Section 2):
  3. The tests or combinations thereof should be selected from the following types, contained in the Parts of EN ISO 22476 and covered in this Section:

    Table 2.1 gives a broad overview for the applicability of the tests in different ground conditions.

  4. Other complementary internationally recognised investigation methods, for instance geophysical methods, may be used.

4.2 General requirements

4.2.1 Planning a specific test programme

  1. P In addition to the recommendations given in 2.3 and the requirements given in 2.4 and 4.1 (2), the following information shall be established:
  2. P When designing the ground investigation programme, the selection of the type of field tests and of the test equipment shall aim at obtaining the best technical and economical solution for the intended purpose.

    NOTE see also Table 2.1 and B.2.

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4.2.2 Execution

  1. Image P For the tests covered in this Section, equipment and procedures shall correspond to the requirements in EN ISO 22476-1 to EN ISO 22476-9, EN ISO 22476-12 and EN ISO 22476-13. Image

    NOTE Further information on a procedure, presentation and evaluation of the weight sounding test and the flat dilatometer test can be found in CEN ISO/TS 22476-10 and CEN ISO/TS 22476-1 1 respectively.

  2. P If the results obtained during the ongoing investigation do not correspond to the initial information (see Section 2) about the test site and/or the aim of the investigation, additional measures shall be considered such as:
  3. If the desired investigation depth is not reached, the client should be informed immediately.

4.2.3 Evaluation

  1. P In evaluating the field test results, especially in the context of deriving geotechnical parameters/coefficients from the results, any additional information about the ground conditions shall be considered.
  2. P Results from any sampling by drilling and excavations according to Section 3 shall be available and shall be used in evaluating the test results.
  3. P In evaluating the test results, the possible geotechnical and equipment influences on the measured parameters shall be considered. When a soil or rock formation exhibits anisotropy, attention shall be paid to the axis of loading with respect to the anisotropy.
  4. P If correlations are used to derive geotechnical parameters/coefficients, their suitability shall be considered for each particular project.
  5. P When using Annexes D to K, it shall be ensured that the ground conditions of the site under investigation (soil type, uniformity coefficient, consistency index etc.) are compatible with the boundary conditions given for the correlation. Local experience shall be used for confirmation, if available.

    NOTE, 1 Annexes D to K give examples of correlations for the establishment of derived values and for the application of test values to design methods.

    NOTE 2 X.3 contains examples of correlations for the establishment of derived values from test results and also the use of test results directly in design.

41

Image 4.3 Cone penetration and piezocone penetration tests (CPT, CPTU, CPTM) Image

4.3.1 Objectives

  1. The objective of the cone penetration test (CPT) is to determine the resistance of soil and soft rock to the penetration of a cone and the local friction on a sleeve.
  2. P The CPT consists of pushing a cone penetrometer vertically into the soil using a series of push rods. The cone penetrometer shall be pushed into the soil at a constant rate of penetration. The cone penetrometer comprises the cone and if appropriate a cylindrical shaft or friction sleeve. The penetration resistance of the cone (qc) as well as, if appropriate, the local friction on the friction sleeve shall be measured.
  3. P For electrical CPTs, all measurements shall be made by sensors contained in the cone penetrometer.
  4. For mechanical CPTs, the measurements are generally made remotely.
  5. The piezocone penetration test, CPTU, is an electrical CPT, which includes additional instrumentation to measure the pore water pressure during penetration at the level of the base of the cone.
  6. The CPTU results should be used mainly for the determination of a soil profile together with results from sampling by drilling and excavations according to Section 3 or in comparison with other field tests.
  7. The results may also be used for the determination of geotechnical parameters such as the strength and deformation properties of soil and soft rock provided penetration is possible, and for direct input to design methods, generally in coarse and fine soil but also possibly in other deposits.
  8. The results may also be used to determine the length of piles and their compressive or tensile resistance or the dimensions of shallow foundations.

4.3.2 Specific requirements

  1. Image P The tests shall be carried out and reported in accordance with a method that conforms to the requirements given in EN ISO 22476-1 for the electrical CPT and CPTU, or EN ISO 22476-12 for the CPTM. Image
  2. P When planning the test programme for a project, the following items shall be decided in addition to the requirements given in 4.2.1:
  3. P Any deviation from the requirements given in EN ISO 22476-1 or EN ISO 22476-12 shall be justified and reported. In particular, any influence on the results shall be commented upon.
42

4.3.3 Evaluation of test results

  1. P In addition to the requirements given in 4.2, the field and test reports according to EN ISO 22476-1 or EN ISO 22476-12 shall be used for evaluation purposes.
  2. P Possible geotechnical influences on the penetration resistance shall be considered in evaluating the test results, e.g. in clays, the cone penetration resistance corrected for pore water pressure effects, (qt), should be used in evaluation.

4.3.4 Use of test results and derived values

4.3.3.1 Bearing resistance and settlement of spread foundations
  1. P If the bearing resistance or the settlement of a spread foundation is derived from CPT results, either a semi-empirical or an analytical design method shall be used.

    NOTE See, for example, EN 1997-1:2004, Annex D or F.

  2. P If a semi-empirical method is used, all the features of the method shall be taken into account.

    NOTE If, for instance, the semi-empirical method to determine the settlement of spread foundations from CPT results is used (see D.3), only Young’s modulus of elasticity derived from qc is applied in this particular method as shown in the example.

  3. If the sample analytical method for bearing resistance of Annex D in EN 1997-1:2004 is used, the undrained shear strength of fine soil, (cu) may be determined for a CPT from:

    Image

    Or, in the case of a CPTU, from:

    Image

    where

    qc is the cone penetration resistance
    qt is the cone penetration resistance corrected for pore water pressure effects;
    Nk and Nkt are coefficients estimated from local experience or reliable correlations
    σvo is the initial total vertical overburden stress at the depth under consideration;
  4. If the sample analytical method for bearing resistance calculation of Annex D of EN 1997-1:2004 is used, the angle of shearing resistance (φ′) may be determined from the cone resistance (qc), on the basis of local experience, taking into account depth effects, when relevant.

    NOTE 1 An example of ranges of values to estimate φ′ from qc for quartz and feldspar sands is given in D.1, for estimating the bearing resistance of spread foundations when depth effects do not need to be taken into account.

    NOTE 2 In addition, an example for a correlation between φ′ and qc for poorly-graded sands is given in D.2. The correlation given in D.2 should be considered as giving a conservative estimate.

  5. More elaborate methods may also be used for determining φ′ from qc taking into account the effective vertical stress, the compressibility, and the over-consolidation ratio. 43
  6. If an adjusted elasticity method is used for calculating settlements of spread foundations from CPT results, the correlation between cone resistance (qc) and the drained (long term) Young’s modulus of elasticity (E′) depends on the nature of the method: the semi-empirical elasticity method, or the theoretical elastic method.

    NOTE An adjusted elasticity method is given in EN 1997-1:2004, Annex F.

  7. Semi-empirical methods may be used for calculating settlements in coarse soil.

    NOTE An example is given in D.3.

  8. When a theoretical elastic method is used, the drained (long term) Young’s modulus of elasticity (E′) may be determined from cone resistance (qc), on the basis of local experience.

    NOTE An example of sample values for quartz and feldspar sands is given in D.1 to estimate a value of E′ from qc.

  9. Correlations between the oedometer modulus (Eoed) and the cone resistance (qc) may also be used when calculating settlements of spread foundations. The following relationship between Eoed and qc is often adopted:

    Eoed = α × qc       (4.3)

    where

    α is a correlation factor depending on local experience.

    NOTE An example of a correlation is given in D.4.

  10. When a theoretical elastic method is used to calculate the settlements of spread foundations, a stress dependant oedometer modulus (Eoed), based on qc, may be used.

    NOTE 1 For examples of theoretical elastic methods, see EN 1997-1:2004, Annex F.

    NOTE 2 Examples of correlations between qc and Eoed are given in D.5. The correlations given in D.5 should be considered as conservative estimates.

4.3.4.2 Pile bearing resistance
  1. P If the ultimate compressive or tensile resistance of piles according to EN 1997-1:2004, 7.6.2.3 or 7.6.3.3 is derived from CPT results, calculation rules based on locally established correlations between the results of static load tests and CPT results shall be used.

    NOTE 1 An example for such correlations for coarse soil is shown in D.6.

    NOTE 2 An example is given for the assessment of the compressive resistance of a single pile on the basis of qc- values from a CPT in D.7.

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4.4 Pressuremeter tests (PMT)

4.4.1 Objectives

  1. The objective of the pressuremeter test is to measure in-situ the deformation of soil and soft rock caused by the expansion of a cylindrical flexible membrane under pressure.
  2. P The test consists of inserting a probe containing a cylindrical flexible membrane into the ground either into a pre-formed borehole, or by self-boring or by full displacement pushing. Once at a predetermined depth the membrane is expanded under pressure and readings of pressure and expansion are recorded until a maximum expansion for the particular device is reached.

    NOTE Expansion is measured from radial displacement, or calculated from volume change of the cylindrical membrane.

  3. The test should be used to derive strength and/or deformation parameters of the ground or specific pressuremeter parameters.
  4. The results may be used to derive stress-strain curves in fine soil and soft rock.

4.4.2 Specific requirements

  1. P When planning a test programme for a project the type of pressuremeter to be used shall be specified.
  2. P There are four different types of apparatus generally available, for which the corresponding standards shall be used:

    NOTE The PBP and the MPM are lowered into a test hole created specifically for the pressuremeter test. The SBP is drilled into the ground using an integral cutting head at its lower end such that the probe replaces the material it removes thereby creating its own test hole. The FDP is usually pushed into the ground with an integral cone at its lower end, thereby creating its own test hole. The MPM may in some instances be pushed or driven into the ground. PBP, SBP and FDP probes may take a number of forms, in accordance with the type of installation and measuring systems.

  3. Two different basic test procedures may be used:
  4. P The tests shall be carried out and reported in accordance with a test method that conforms to the requirements for the particular instrument type to be used, (see 4.4.2 (2)P).
  5. P Any deviations from the requirements given in the corresponding standard shall be justified and in particular their influence on the results shall be commented upon.

4.4.3 Evaluation of test results

  1. P If necessary, the applied pressure shall be corrected for membrane stiffness to obtain the true pressure applied to the cylindrical ground contact surface around the probe.
  2. P If a radial displacement type pressuremeter is used, the displacement readings shall be converted to cavity strain and, if testing weak rock, corrected for membrane compression and thinning.
  3. P If a volume displacement type pressuremeter is used (e.g. MPM), the volume reading shall be corrected for system expansion.
  4. P In addition to the requirements given in 4.2, the field and test reports according to EN ISO 22476-4 EN ISO 22476-5 EN ISO 22476- 6 and EN ISO 22476-8 for the specific test type shall be used for the basis of any further evaluation.
  5. In addition to the plots required by the individual equipment test standard, the list of additional plots in Table 4.1 should be considered.
    Table 4.1 — A list of additional plots
    Probe Ground type Abscissa Ordinate
    Radial displacment type
    Self-bored, pushed in All Cavity strain for each arm Applied pressure
    Pre-bored All Cavity strain for each pair of arms Applied pressure
    Self bored All initial cavity strain for each arm Applied pressure
    All All Cavity strain for unload-reload cycle for each arm Applied pressure
    All Clay Logarithm of cavity strain for each arm Applied pressure
    All Sands Natural logarithm of current cavity strain for each arm Natural logarithm of effective applied pressure
    Volume displacement type (except MPM)a
    Pre-bored All Volume change Applied pressure
    Pre-bored All Rate of change of volume Applied pressure
    a For MPM tests, the pressure is plotted as abscissa and the volume change as ordinate.
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4.4.4 Use of test results and derived values

4.4.4.1 General criteria
  1. P If an indirect or analytical design method is used, the geotechnical parameters of shear strength and shear modulus shall be derived from the pressuremeter curve using methods relevant for the particular test and equipment type.
  2. P If a direct or semi-empirical design method is used, all the features of the method shall be taken into account.

    NOTE Direct foundation design procedures use directly the measurements from field tests, instead of conventional soil properties.

  3. P If, for instance, the semi-empirical method to determine the settlement of spread foundations from MPM results is used, only the modulus (EM) determined from Menard pressuremeter results shall be applied in this particular method.

    NOTE Examples of calculations of settlements can be found in E.2.

4.4.4.2 Bearing resistance of spread foundations
  1. P If a semi-empirical method is used, then all aspects relating to the method need to be followed, in particular the specification for the pressuremeter type used in establishing the method. EN ISO 22476-4 shall be followed.

    NOTE 1 The semi-empirical method according to Menard is given in EN 1997-1:2004, Annex E.

    NOTE 2 An example of the calculation of the bearing resistance is given in E.1.

  2. If an analytical method is used, the strength of the soil may be determined using empirical and theoretical methods but only on the basis of local experience.

    NOTE Examples of analytical methods are given in EN 1997-1:2004, Annex D.

  3. The angle of shearing resistance (φ′) may be determined from an SBP test in coarse soil by theoretical methods and from FDP and PBP tests using empirical correlations but only on the basis of local experience.
4.4.4.3 Settlement of spread foundations
  1. The settlement of spread foundations may be determined from MPM tests using a semi-empirical method.

    NOTE An example of the calculation is given in E.2.

  2. If an analytical method is used, the stiffness of the soil may be determined using theoretical models to interpret the pressuremeter test but only on the basis of local experience.

    NOTE Examples of analytical methods are given in EN 1997-1:2004, Annex F.

47
4.4.4.4 Pile bearing resistance
  1. The ultimate compressive resistance of piles may be derived directly from stress controlled tests.

    NOTE An example of the calculation of the ultimate compressive resistance is given in E.3.

  2. When the ultimate compressive or tensile resistance of a pile is derived indirectly from pressuremeter test results, an analytical method may be applied to derive values of base and shaft resistance but only on the basis on local experience.

4.5 Flexible dilatometer test (FDT)

4.5.1 Objectives

  1. The objective of the flexible dilatometer test is to measure in-situ the deformability of rock (rock dilatometer test, RDT), and soil (soil dilatometer test, SDT) from measurements of the radial expansion of a borehole section under a known uniform radial pressure applied by means of a cylindrical dilatometer probe.
  2. P The test consists of inserting a cylindrical probe, having an outer expandable flexible membrane, into a borehole, and measuring, at selected time intervals or in a semi-continuous manner, the radial displacement of the borehole while inflating the probe under known radial pressure.
  3. The RDT should be used mainly in soft and hard rock formations while the SDT should be used primarily in soft to stiff soil to obtain profiles of deformability variations with depth.
  4. The results of cylindrical dilatometer tests may be used to determine the deformation and creep properties in-situ when testing intact rock.
  5. In fragile or clayey rock, and in fractured or closely jointed formations, where core recovery is poor or inadequate for the purpose of obtaining representative samples for laboratory testing, the cylindrical dilatometer test may be used for rapid index logging of boreholes and for comparisons of relative deformability of different rock strata.

4.5.2 Specific requirements

  1. P When planning a test programme for a project, the specific requirements of the device to be used shall be specified.
  2. P The tests shall be carried out and reported in accordance with a test method that conforms to EN ISO 22476-5.
  3. P Any deviations from the requirements given in EN ISO 22476-5 shall be justified and in particular their influence on the results shall be commented upon.

4.5.3 Evaluation of test results

  1. P In addition to the requirements given in 4.2, the field and test reports according to EN ISO 22476-5 for the specific test type shall be used for evaluation purposes. 48
  2. The interpretation of flexible dilatometer tests requires that the Poisson’s ratio of the soil or rock should either be known or assumed.

4.5.4 Use of test results and derived values

  1. The results of dilatometer tests may be used to check the serviceability limit state of spread foundations on soil or rock through a deformation analysis.
  2. When performing a deformation analysis, the Young’s modulus of elasticity (E) may be taken equal to the dilatometer modulus (EFDT) on the assumption that the soil or rock is linearly elastic and isotropic.
  3. P When an indirect or analytical design method is used, the geotechnical parameters of shear modulus shall be derived from the dilatometer curve using methods relevant for that particular test type.

4.6 Standard penetration test (SPT)

4.6.1 Objectives

  1. The objectives of the standard penetration test are the determination of the resistance of soil at the base of a borehole to the dynamic penetration of a split barrel sampler (or solid cone) and the obtaining of disturbed samples for identification purposes.
  2. P The sampler shall be driven into the soil by dropping a hammer of 63,5 kg mass onto an anvil or drive head from a height of 760 mm. The number of blows (N) necessary to achieve a penetration of the sampler of 300 mm (after its penetration under gravity and below a seating drive) is the penetration resistance.
  3. The test should be used mainly for the determination of the strength and deformation properties of coarse soil.
  4. Valuable additional data may also be obtained in other types of soil.

4.6.2 Specific requirements

  1. P The tests shall be carried out and reported in accordance with EN ISO 22476-3.
  2. P Any deviation from the requirements given in EN ISO 22476-3 shall be justified and in particular its influence on the results of the test shall be commented upon.

4.6.3 Evaluation of test results

  1. P In addition to the requirements given in 4.2, the field and test reports according to EN ISO 22476-3 shall be used for evaluation purposes.
  2. P Existing design methods of foundations based on the SPT are of empirical nature. Equipment-related operating methods have been adapted to obtain more reliable results. Therefore, the application of appropriate correction factors for interpreting the results shall be considered (see EN ISO 22476-3). 49
  3. P The energy ratio (Er) has to be known for the equipment if the results are to be used for the quantitative evaluation of foundations or for the comparison of the results. Er is defined as the ratio of the actual energy Emeas (measured energy during calibration) delivered by the drive-weight assembly into the drive rod below the anvil, to the theoretical energy (Etheor) as calculated for the drive-weight assembly. The measured number of blows (N) shall be corrected accordingly (see EN ISO 22476-3).
  4. In sands, the energy losses due to rod length and the effect of effective overburden pressure should be taken into account accordingly (see EN ISO 22476-3:2005, A.2 and A.4).
  5. Other corrections should be considered, such as taking into account the use of liners (see EN ISO 22476-3:2005, A.3) or the use of a solid cone.

4.6.4 Use of test results and derived values

4.6.4.1 General criteria
  1. When dealing with sands, a wide empirical experience in the use of this test is available, such as for the quantitative evaluation of the density index, the bearing resistance and the settlement of foundations, even though the results should be considered as only a rough approximation. Most of the existing methods are still based on uncorrected or partly corrected values.
  2. There is no general agreement on the use of the SPT results in clayey soil. In principle, it should be restricted to a qualitative evaluation of the soil profile or to a qualitative estimate of the strength properties of the soil.
  3. The SPT results may sometimes be used in a quantitative way in clayey soil under well-known local conditions, when directly correlated to other appropriate tests.
4.6.4.2 Bearing resistance of spread foundations in sands
  1. If an analytical method for the calculation of bearing resistance is used, the effective angle of shearing resistance (φ′) may be derived from SPT results.

    NOTE For examples of analytical methods for the calculation of bearing resistance, see EN 1997-1:2004, Annex D.

  2. The value of φ′ may be derived empirically from:

    NOTE 1 See for example F.1 and F.2.

    NOTE 2 The relationships given in F.1 can be used to determine the density index ID from either N60 or (N1)60, (see EN ISO 22476-3).

  3. The resistance of sand to deformation is often increased the longer the geological period of consolidation. This “ageing” effect is reflected in higher blow counts and should be taken into account.
  4. Over-consolidation should be taken into account because it increases the blow counts, for the same values of ID and σ′v0. 50

    NOTE 1 In F.1, some sample correlations are shown by the means of which the effect of both ageing and over-consolidation can be taken into account.

    NOTE 2 When correcting for over-consolidation and ageing effects, the resultant derived φ′ values, using the density index, from the correlations in F.2 can be conservative.

4.6.4.3 Settlement of spread foundations in sand
  1. If a purely elastic design method is used, the drained Young’s modulus of elasticity (E′) may be derived from the N-values through empirical correlations.
  2. Alternatively, the density index may be derived based on the N60-value. Then an appropriate correlation may be used to obtain E′ through the density index.
  3. The direct design methods are based on comparisons of the N-values and results of plate loading tests or records of measured settlements of foundations. Allowable bearing resistance for a maximum settlement of 25 mm or the settlement corresponding to a given applied pressure can be obtained through the corresponding procedures with reference to the width of the footing, its embedment in the ground and groundwater table position.

    NOTE The sample method for the calculation of the settlements caused by spread foundations in sand, as given in F.3, can be used.

4.6.4.4 Pile bearing resistance in sand
  1. P If the ultimate compressive or tensile resistance of piles is derived from SPT results according to EN 1997-1:2004, 7.6.2.3 or 7.6.3.3, calculation rules based on locally established correlations between the results of static load test and SPT results shall be used.

4.7 Dynamic probing tests (DP)

4.7.1 Objectives

  1. The objective of the dynamic probing tests is to determine the resistance of soil and soft rock in-situ to the dynamic penetration of a cone.
  2. P A hammer of a given mass and falling height shall be used to drive the cone. The penetration resistance is defined as the number of blows required to drive the penetrometer over a defined distance. A continuous record shall be provided with respect to depth. No samples are recovered.
  3. The test results should be used particularly for the determination of a soil profile together with results from sampling by drilling and excavations according to Section 3 or as a relative comparison of other in-situ tests.
  4. The results may also be used for the determination of the strength and deformation properties of soil, generally of the coarse type but also possibly in fine soil, through appropriate correlations.
  5. The results can also be used to determine the depth to very dense ground layers indicating for instance the length of end bearing piles.
51

4.7.2 Specific requirements

  1. P For planning the specific test programme for a project, in addition to the requirements given in 4.2.1, the type of required DP test according to EN ISO 22476-2, shall be decided upon.
  2. P The tests shall be carried out and reported in accordance with EN ISO 22476-2.

    NOTE Five procedures are available according to EN ISO 22476-2, covering a wide range of specific work per blow; DPL, DPM, DPH, DPSH-A and DPSH-B as follows.

  3. P Any deviation from the requirements given in EN ISO 22476-2 shall be justified and in particular its influence on the results of the test shall be commented upon.

    NOTE Deviations exist with respect to:

  4. In locations with special difficulties of accessibility, lighter equipment and procedures other than those specified in EN ISO 22476-2 may be used.

4.7.3 Evaluation of test results

  1. P In addition to the requirements given in 4.2, the field and test reports according to EN ISO 22476-2 shall be used for evaluation purposes.
  2. P Possible geotechnical and equipment influences on the penetration resistance according to EN ISO 22476-2:2005, 5.4 shall be considered in evaluating the test results.

4.7.4 Use of test results and derived values

  1. For coarse soil, it is possible to obtain correlations with some geotechnical parameters and field tests. The correlations may be used in a quantitative evaluation for foundation design, provided the friction along the rods is negligible, or duly corrected.
  2. For fine soil, the quantitative use of the results should be employed only under well-known local conditions and supported by specific correlations. The skin friction during the test is a factor of special concern with this type of soil and should be duly taken into account.
  3. Several correlations have been established among the different dynamic probing tests and between them and other tests or geotechnical parameters. In some cases the friction along the rods has been eliminated or corrected, but the actual energy transmitted to the probe has not been measured. Therefore they cannot be considered valid in general.

    NOTE 1 Examples of such correlations are included in Annex G.

    52

    NOTE 2 The correlations given in Annex G should be considered as conservative estimates.

  4. If an analytical method for bearing resistance of spread foundations is used, the angle of shearing resistance (φ′) of coarse soil may be determined from the number of blows and the corresponding density index (ID) with correlations.

    NOTE 1 An example of an analytical method is given in EN 1997-1:2004, D.4.

    NOTE 2 Such correlations for the determination of φ′ are given as examples in G.1 and G.2.

  5. If a theoretical elastic method is applied to calculate the settlements of spread foundations, the oedometer modulus (Eoed) derived from the number of blows may be used.

    NOTE 1 Examples of theoretical elastic methods are given in EN 1997-1:2004, Annex F.

    NOTE 2 Corresponding examples of correlations for the determination of the oedometer modulus are given in G.3.

  6. If well-established correlations between ultimate compressive resistance from static pile load tests (see EN 1997-1:2004, 7.6.2.3) and cone penetration resistance (qc) in coarse soil are used for the design, qc may be estimated from N10 or N20 values using established relationships.

    NOTE 1 Examples for DPH correlations are given in G.4.

    NOTE 2 An example of correlations between the results of different dynamic probing tests is given in G.5.

4.8 Weight sounding test (WST)

4.8.1 Objectives

  1. The objective of the weight sounding test is the determination of the resistance of soil in situ to the static and/or rotational penetration of a screw-shaped point.
  2. P The weight sounding test shall be made as a static sounding in soft soil if the penetration resistance is less than 1 kN. If the resistance exceeds 1 kN, the penetrometer shall be rotated, manually or mechanically, and the number of half-turns for a given depth of penetration recorded. A continuous record is provided with respect to depth but no samples are recovered.

    NOTE Further information on a procedure, presentation and evaluation for the WST can be found in CEN ISO/TS 22476-10, (see X.3.5).

  3. The weight sounding test should primarily be used to give a continuous soil profile and an indication of the layer sequence. The penetrability in even stiff clays and dense sands is good.
  4. The weight sounding test may also be used to estimate the density index of coarse soil.
  5. The results can also be used to determine the depth to very dense ground layers indicating the length of end bearing piles.

4.8.2 Specific requirements

  1. The tests should be carried out and reported in accordance with a recognised method. 53
  2. P Any deviation from the requirements in the method referred to in (1) shall be justified and in particular its influence on the results of the test shall be commented upon.

    NOTE Further information on a procedure, presentation and evaluation for the weight sounding test can be found in CEN ISO/TS 22476-10.

4.8.3 Evaluation of test results

  1. P The requirements given in 4.2 shall be followed for the evaluation of the test results.
  2. In addition, the field and test reports, according to the method referred to in 4.8.2 (1), should be used for evaluation purposes.

    NOTE Further information on a procedure, presentation and evaluation for weight sounding test can be found in CEN ISO/TS 22476-10.

  3. Image The following influences can affect the evaluation of the results. Image

4.8.4 Use of test results and derived values

  1. P When the bearing resistance or the settlement of a spread foundation is derived from weight sounding test results, an analytical design method shall be used.
  2. If an analytical method for bearing resistance is used, the angle of shearing resistance φ′ may be determined from correlations with weight sounding resistance.

    NOTE Examples of analytical methods are given in EN 1997-1:2004, Annex D.

  3. Such correlations should be based upon comparable experience, relevant to the design situation.

    NOTE Annex H presents an example correlation, derived for quartz and feldspar sands in a European region.

  4. If an adjusted elasticity method is used for calculating settlements of spread foundations from weight sounding results, the drained (long term) Young’s modulus of elasticity (E′) may be determined from weight sounding resistance on the basis of local experience. In the case of 54 quartz and feldspar sands, for example, the angle of shearing resistance (φ′) may be estimated from the weight sounding resistance.

    NOTE 1 Such an adjusted elasticity method is given in EN 1997-1:2004, Annex F.

    Image NOTE 2 Examples for correlations to estimate the drained (long term) Young’s modulus of elasticity (E′) and the angle of shearing resistance (φ′) of quartz and feldspar sands are given in Annex H. Image

  5. In coarse soil, the weight sounding resistance may also be used in direct estimation of the bearing capacity of spread foundation and piles.
  6. In fine soil, the weight sounding resistance may be used to estimate the undrained shear strength of soil, based on local experience, considering the sensitivity of the soil and water conditions in the borehole.

4.9 Field vane test (FVT)

4.9.1 Objectives

  1. The objectives of the field vane test are the measurement of the resistance to rotation in-situ of a vane installed in soft fine soil for the determination of the undrained shear strength and the sensitivity.
  2. P The field vane test shall be carried out with a rectangular vane, consisting of four plates fixed at 90° angles to each other, pushed into the soil to the desired depth and rotated.
  3. The field vane test may also be used for the determination of the undrained shear strength in stiff clays, silts and glacial clays. The reliability of test results varies depending on the type of soil.
  4. After extensive rotation of the vane, whereby the soil along the failure surface becomes thoroughly remoulded, the remoulded shear strength value can be measured and the soil’s sensitivity can be calculated.

4.9.2 Specific requirements

  1. The tests should be carried out and reported in accordance with requirements given in EN ISO 22476-9.
  2. P Any deviation from the requirements given in EN ISO 22476-9 shall be justified, and in particular its influence on the results of the test shall be commented upon.

4.9.3 Evaluation of test results

  1. P In addition to the requirements given in 4.2, the field and the test reports according to EN ISO 22476-9 shall be used for evaluation purposes.
  2. The results of other field test, e.g. from CPT, SPT, WST or DP if conducted, should be available and considered.

4.9.4 Use of test results and derived values

55
  1. P If the bearing resistance of a spread foundation, the ultimate compressive or tensile resistance of piles or stability of slopes are derived based on vane test results, an analytical design method shall be used.
  2. P In order to obtain derived values for the undrained shear strength from field vane test results, the test result (cfv) shall be corrected based on:

    cu = μ × cfv.       (4.4)

    The correction factor μ shall be determined based on local experience.

  3. Existing correction factors are usually related to the liquid limit plasticity index, the effective vertical stress or the degree of consolidation.

    NOTE Annex I gives examples of such correction factors.

4.10 Flat dilatometer test (DMT)

4.10.1 Objectives

  1. The objectives of the flat dilatometer test are the determination of the in-situ strength and deformation properties of soil by expanding a thin circular steel membrane mounted flush on one face of a blade-shaped steel probe inserted vertically into the ground.
  2. P The test consists of measuring the pressures when the membrane is flush with the blade and just begins to move and when the displacement in the centre of the membrane reaches 1,10 mm into the soil. The test shall be performed at selected depths or in a semi-continuous manner.
  3. The results of DMT tests may be used to obtain information on soil stratigraphy, in-situ state of stress, deformation properties and shear strength.
  4. The DMT test should primarily be used in clays, silts and sands where particles are small compared to the size of the membrane.

    NOTE Further information on a procedure, presentation and evaluation of the DMT can be found in CEN ISO/TS 22476-11, (see X.3.7).

4.10.2 Specific requirements

  1. The tests should be carried out and reported in accordance with a recognised method.
  2. P Any deviations from the requirements given in the method referred to in (1) shall be justified and in particular their influence on the results shall be commented upon.

    NOTE Further information on a procedure, presentation and evaluation of the DMT can be found in CEN ISO/TS 22476-1 1

4.10.3 Evaluation of test results

  1. P The requirements given in 4.2, shall be followed for the evaluation of the test results. 56
  2. In addition the field and test reports, according to the method referred to in 4.10.2 (1), should be used for evaluation purposes.

    NOTE Further information on a procedure, presentation and evaluation of the DMT can be found in CEN ISO/TS 22476-11

4.10.4 Use of test results and derived values

4.10.4.1 Bearing resistance and settlement of spread foundations
  1. P If the bearing resistance of spread foundations is derived from DMT results, an analytical design method shall be used.
  2. If an analytical method is used, the derived value of the undrained shear strength (cu) of non-cemented clays, for which the DMT test results show material index IDMT < 0,8, may be determined using the following relationship:

    cu = 0,22 σ′v0 × (0,5 KDMT)1.25      (4.5)

    where

    KDMT is the horizontal stress index or any other well documented relationship based on local experience.

    NOTE Examples of analytical methods are given in EN 1997-1:2004, Annex D.

  3. If applying an adjusted elasticity method, the one-dimensional settlement of spread foundations may be calculated using values of the one-dimensional tangent modulus (Eoed) determined from results of DMT tests. In fine soil, such procedures should be applied only when the sum of the effective overburden pressure and the stress increase induced by the foundation load is less than the pre-consolidation pressure.

    NOTE 1 Such an adjusted elasticity method is given in EN 1997-1:2004, Annex F.

    NOTE 2 An example of such a determination of settlements is shown in Annex J.

4.10.4.2 Pile bearing resistance
  1. P If the ultimate compressive or tensile resistance of piles is derived from DMT results, an analytical calculation method shall be applied to derive the values of base and shaft resistance.

4.11 Plate loading test (PLT)

4.11.1 Objectives

  1. The objective of the plate loading test is the determination of the vertical deformation and strength properties of soil and rock masses in-situ by recording the load and the corresponding settlement when a rigid plate modelling a foundation is loading the ground.
  2. P The plate loading test shall be carried out on a thoroughly levelled and undisturbed surface either at ground level or on the bottom of an excavation at a certain depth or the bottom of a large diameter borehole, an exploration shaft or gallery. 57
  3. The test is applied in all soils, fills and rock but normally should not be used for very soft fine soil.

4.11.2 Specific requirements

  1. P The test shall be carried out and reported in accordance with EN ISO 22476-13.
  2. P Any deviation from the requirements given in EN ISO 22476-13 shall be justified and in particular its influence on the results shall be commented upon.

    NOTE Deviations exist, for example with respect to plate size and test procedure (incremental loading, constant rate of deformation).

4.11.3 Evaluation of test results

  1. P In addition to the requirements given in 4.2, the field and the test reports according to EN ISO 22476-13 shall be used for evaluation purposes.

4.11.4 Use of test results and derived values

  1. The results of a PLT may be used to predict the behaviour of spread foundations.
  2. For deriving geotechnical parameters of a homogeneous layer (for use in indirect design methods), the layer should have a thickness beneath the plate of at least two times the width or diameter of the plate.
  3. Results of a PLT may only be used for direct design methods if:
  4. If an analytical design method for bearing resistance is used, the undrained shear strength (cu) may be derived from a PLT conducted at a constant rate of penetration, sufficiently fast to practically preclude any drainage.

    NOTE 1 Examples of analytical design methods for bearing resistance are given in EN 1997-1:2004, Annex D.

    NOTE 2 An example of a relationship used for deriving the value of cu is given in K.1.

  5. If an adjusted elasticity method for settlement evaluation is used, the Young’s modulus of elasticity (E) may be derived from the plate settlement modulus (EPLT), based on established experience.

    NOTE 1 Such an adjusted elasticity method for settlement evaluation is given in EN 1997-1:2004, Annex F.

    NOTE 2 The determination of EPLT is shown in K.2.

  6. The coefficient of sub-grade reaction (ks) for evaluating deformations may be derived from results of an incremental loading test.

    NOTE An example of the calculation of ks is given in K.3.

    58
  7. For direct design, the results of PLT may be transferred directly to the foundation problem without using any geotechnical parameters.
  8. Settlements of footings in sand may be derived from PLT results.

    NOTE An example is given in K.4.

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Section 5 Laboratory tests on soil and rock

5.1 General

  1. P The laboratory test program shall be established in conjunction with the other parts of the ground investigation program (see Section 2 for more details).
  2. Whenever possible, the information obtained from field tests and soundings should be used for selecting the test samples (see 2.4.1.3).

5.2 General requirements for laboratory tests

5.2.1. General requirements

  1. The requirements given in this section should be considered a minimum.
  2. Additional specifications, additional presentation requirements or additional interpretation, as appropriate for the ground conditions or geotechnical aspects of interest, may be required.
  3. P Details of the tests required to determine the parameters needed for design shall be specified.

5.2.2 Procedures, equipment and presentation

  1. P Tests shall be carried out and reported according to existing EN and EN ISO documents.

    NOTE CEN ISO/TS documents are available for a number of laboratory tests. Some EN ISO documents are under preparation..

  2. Provided the requirements of this standard are met, alternative test methods and procedures may be selected.
  3. P Checks shall be made that the laboratory equipment used is adequate, fit for its purpose, calibrated and within the calibration requirements.
  4. The reliability of the equipment and procedures should be checked by comparing the test results with data obtained on comparable soil or rock types.
  5. P The test methods and procedures used shall be reported together with the test results. Any deviations from a standard test procedure shall be reported and justified.
  6. If appropriate, the results of laboratory soil classification tests should be presented together with the soil profile on a plot summarizing the soil description and all classification results.
  7. If possible and required, the location of the other laboratory tests (such as oedometer and triaxial tests) should be indicated on the same plot.

5.2.3 Evaluation of test results

  1. Requirements for evaluation of laboratory test results are given in 6.3. 60
  2. Results of individual tests should be compared with other test results to check that no contradiction exists between the available data.
  3. The test results should be checked with values found in the literature, correlations with index properties and comparable experience.

5.3 Preparation of soil specimens for testing

5.3.1 Objective

  1. The objective of the preparation of soil for laboratory tests is to provide test specimens that are as representative as possible of the soil from which the samples are taken.
  2. For the purposes of preparation, five types of soil specimens may be distinguished: disturbed, undisturbed, re-compacted, remoulded and reconstituted specimens.

5.3.2 Requirements

5.3.2.1 Quantity of soil
  1. P The soil specimen used for testing shall be sufficiently large to take account of:

    NOTE Minimum masses of disturbed soil for classification tests and tests on re-compacted specimens and masses of soil required for preparation of undisturbed specimens for strength and compressibility tests are given in Annex L.

5.3.2.2 Handling and processing
  1. P The requirements of EN-ISO 22475-1 shall be observed.
  2. P All samples shall be clearly and unambiguously labelled.
  3. P Soil samples shall be protected at all times against damage, deterioration and excessive changes in temperature. Special care shall be taken with undisturbed samples to prevent distortion and loss of water during the preparation of test specimens. The material used for the sampling containers shall not react with the contained soil.
  4. P Soil shall not be allowed to dry before testing if the test results can be affected by a loss of moisture.
  5. Undisturbed samples should be prepared under conditions of controlled humidity. If preparation is interrupted, the specimen should be protected from changes in water content.
  6. P If disaggregating processes are applied, the breaking down of individual particles shall be avoided. If special treatment of bonded and cemented soil is required, this shall be specified.
  7. P Subdivision methods shall ensure that representative portions are obtained, avoiding segregation of large particles.
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5.4 Preparation of rock specimens for testing

5.4.1 Objective

  1. The objective of preparing specimens for testing rock is to provide specimens that are as representative as possible of a rock formation.

    NOTE Annexes T to W and X.2 provide more detail on the preparation of rock specimens for testing and some guidelines.

5.4.2 Requirements

  1. P It shall be specified how a rock specimen is prepared. If these specifications cannot be met, the specimen shall be prepared as near to the specifications as possible and it shall be reported how the specimen has been prepared.
  2. P All instruments and assemblies for determining straightness, flatness and perpendicularity of end surfaces shall be controlled on a registered regular time basis with tolerances satisfying at least the requirements of the specific rock tests.
  3. P The following shall be specified:
  4. Image P Any change in water content should be avoided. If a change in the natural water content should occur, its effect shall be counteracted as part of the preparation for testing, if relevant. Image
  5. The cause and effect of any change in water content should be reported.
  6. P The need for re-coring to a specified dimension shall be defined with reference to the laboratory coring method, coolant applied and the need for re-saturation of the test specimens.
  7. Together with the data and results for the particular test, the following should be recorded and reported:
  8. The following information on the samples should be given for the interpretation of the test results:

5.5 Tests for classification, identification and description of soil

5.5.1 General

  1. P Classification, identification and description of soil shall be made in accordance with EN ISO 14688-1 and EN ISO 14688-2.

    NOTE Annex M provides more details on individual classification tests and their interpretation, and a guideline for the minimum number of samples and tests in one stratum.

5.5.2 Requirements for all classification tests

  1. For all classification tests, special caution should be exercised when choosing the temperature for oven-drying, as too high a temperature can have detrimental effects on the value measured.

5.5.3 Water content determination

5.5.3.1 Objective and requirements
  1. The objective of the test is to determine the water content of a soil material. The water content is defined as the ratio of the mass of free water to the mass of dry soil.
  2. Soil specimens for measuring the water content should be at least of Quality Class 3, according to 3.4.
  3. If a sample contains more than one soil type, water contents should be determined on the specimens representing the different soil types.

    NOTE Further information on a procedure, presentation and evaluation for the determination of water content can be found in CEN ISO/TS 17892-1, (see X.4.1.2).

5.5.3.2 Evaluation of test results
  1. P When evaluating the results, the presence of significant amounts of gypsum, highly organic soil, materials in which the pore water contains dissolved solids and soil with closed pores filled with water, shall be accounted for, if relevant.
  2. The extent to which the water content measured in the laboratory on the soil “as received” is representative of the “in situ” value should be checked. The effects of the sampling method, transport and handling, specimen preparation method and laboratory environment, should be taken into account in this assessment.
  3. For the soil referred to in (1)P, a drying temperature of approximately 50 °C may be more appropriate than the usually prescribed (105 ± 5) °C, but the results obtained should be considered with caution.
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5.5.4 Bulk density determination

5.5.4.1 Objective and requirements
  1. The test is used to determine the bulk (total) mass density of a soil, including any liquid or gas contained.
  2. The test specimens should be at least of Quality Class 2, according to 3.4.
  3. P The test method to be used shall be specified.

    NOTE Further information on a procedure, presentation and evaluation of bulk density determination can be found in CEN ISO/TS 17892-2, (see X.4.1.3).

5.5.4.2 Evaluation and use of test results
  1. The evaluation of the test results should consider the possible sample disturbance.
  2. Except in the case of special sampling methods, the laboratory determination of the density of a coarse soil is generally only approximate.
  3. The bulk density can be used in establishing design values of actions derived from soil and in processing results of other laboratory tests.
  4. The bulk density can also be used in evaluating other soil characteristics. For example, in conjunction with the water content, in computing the density of dry soil.

5.5.5 Particle density determination

5.5.5.1 Objective and requirements
  1. The aim of the test is to determine by a conventional method the density of solid soil particles.
  2. P The choice of the test method to be used shall take the soil type into account.

    NOTE Further information on a procedure, presentation and evaluation of determination of particle density can be found in CEN ISO/TS 17892-3, (see X.4.1.4).

5.5.5.2 Evaluation of test results
  1. P If for a particular stratum, the measured values of the particle density are not within the normally expected range of (2 500 to 2 800) kg/m3, the mineralogy of the soil, its organic matter and its geological origin shall be checked.

5.5.6 Particle size analysis

5.5.6.1 Objective and requirements
  1. The objective of the test is to determine the mass percentage of individual particle size ranges found in the soil. 64

    NOTE Further information on a procedure, presentation and evaluation of particle size analysis can he found in CEN ISO/TS 17892-4, (see X.4.1.5).

  2. P Two methods shall be used for particle size analysis, according to the size of the particles:
  3. Equivalent methods may be used, provided that they are calibrated against the two methods mentioned in (2)P.
  4. P Prior to sedimentation, the specimens of fine soil shall not be dried.
  5. Procedures for the removal of organics, salts and carbonates prior to sieving and sedimentation or for corrections to account for the presence of carbonates, salts and organic material should be used, if appropriate.

    NOTE Carbonates and organic matter can have a cementing or coagulating effect and influence the particle size distribution.

  6. It should be taken into account that for some soils, for example chalky soil, treatment for carbonate removal is unsuitable.
5.5.6.2 Evaluation and use of test results
  1. P The report shall mention the following:
  2. The particle size such that n % of the particles by weight are smaller than that size can be denoted Dn. The particle sizes D10, D30 and D60, can be used to determine the coefficient of uniformity and coefficient of curvature.
  3. The particle sizes D15 and D85 can be used in filter criteria for soil.

5.5.7 Consistency limits determination

5.5.7.1 Objective and requirements
  1. The consistency limits (Atterberg limits) comprise the liquid limit, plastic limit and shrinkage limit. Only the determination of the liquid limit and the plastic limit are covered.
  2. The consistency limits are used to characterise the behaviour of clays and silty soil when the water content is changing. Classification of clays and silty soil is mainly based on the consistency limits.
  3. P The testing method to be used for determining the liquid limit (fall cone or Casagrande apparatus) shall be specified. 65
  4. In general for the liquid limit, the fall cone method should be preferred to the Casagrande method. The fall cone method gives more reliable results particularly for low plasticity soil.
  5. The specimens should at least be of Quality Class 4, according to 3.4, if the test results are supposed to characterise the soil in situ.

    NOTE Further information on a procedure, presentation and evaluation of the determination of consistency limits can be found in CEN ISO/TS 17892-12, (see X.4.1.6).

5.5.7.2 Evaluation and use of results
  1. Different geotechnical properties, for example compressibility or optimum water content, can be derived from correlations with the liquid or plastic limits.
  2. The value of the plasticity index IP can be computed from liquid and plastic limits. IP can be used in soil classification and in correlations with some geotechnical soil properties, for example with soil strength.
  3. The value of the consistency index IC (or the liquidity index IL) can be computed from liquid and plasticity limits and from the current water content of the soil. It can be used to represent soil consistency and in correlations with some geotechnical properties.
  4. The activity index IA can be computed from IP and the percentage of clay particles. (IA) can be used in soil classification and in correlations with different geotechnical soil properties, for example with soil strength.

5.5.8 Determination of the density index of granular soil

5.5.8.1 Objective and requirements
  1. The density index relates the void ratio of a soil sample to reference values determined by standard laboratory procedures. It gives an indication of the state of compaction of a free draining granular soil.
  2. P The following shall be specified or checked:
  3. The tested soil should contain less than 10 % of fines (particles passing through the 0,063 mm sieve) and less than 10 % of gravel (particles retained on the 2 mm sieve).
  4. P Density index test results shall be reported together with the available particle size analysis results, natural water content, particle density and percentage of oversize fraction (the latter if applicable). Any deviation with respect to (3) shall be reported.

    NOTE Further information on a procedure, presentation and evaluation the determination of the density index can be found in X.4.1.7.

66
5.5.8.2 Evaluation and use of test results
  1. When evaluating density indexes, it should be taken into account that the maximum and minimum densities obtained in the laboratory do not necessarily represent limiting densities. It is also generally recognised that these tests give densities with a high degree of variability.
  2. The density index can be used to characterise the shear strength and the compressibility of coarse soil.

5.5.9 Soil dispersibility determination

5.5.9.1 Objective
  1. The objective of the test is to identify the dispersive characteristics of clayey soil. Standard tests for classifying soil for engineering purposes do not identify the dispersive characteristics of a soil. Tests for dispersibility are carried out on clayey soil, primarily in connection with earth embankments, mineral sealings and other geotechnical structures in contact with water.
  2. Four test types are considered, (see M.7):
5.5.9.2 Requirements
  1. P The following shall be specified:
  2. P The results from the dispersibility tests shall be linked to the grain size distribution and consistency limits of the sample.
  3. For the pinhole test, the compaction conditions of the soil specimens, for example wet or dry of optimum, and the mixing water (e.g. distilled versus reservoir water) should be specified.
  4. For the double hydrometer test, a third hydrometer test may be specified if it appears necessary to study the effect of reservoir water on the soil in suspension.
  5. For the crumb test, the use of distilled water may be requested in addition to the sodium hydroxide solution.
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5.5.10 Frost susceptibility

5.5.10.1 Objective
  1. The frost susceptibility of soil materials plays an essential role in the design of foundations placed above the freezing front in frost susceptible soil.
  2. Roads, airport runways, railways, buildings on spread foundations, buried pipelines, dams and other structures can be subject to frost heave due to freezing of a frost-susceptible soil having access to water. Frost-susceptible soil can be used in its natural state or as a constructed base for structures.
  3. The risk of frost heaving may be estimated from correlation with soil classification properties (particle size distribution, height of capillary rise and/or fines content) or from laboratory tests on natural, re-compacted and re-consolidated, or reconstituted samples.

    NOTE An example can be found in M.8 and X.5.

5.5.10.2 Requirements
  1. If the estimation of frost susceptibility based on classification properties of the soil does not clearly indicate the absence of risk of frost heaving, frost heaving tests in the laboratory should be run. Examples of soil types indicating the need of laboratory tests in addition to correlations to classification properties include organic soil, peat, saline soil, artificial soil and coarse soil with a wide range of grain size.
  2. To determine the frost susceptibility of a soil in its natural state, natural samples should be tested. To estimate the frost susceptibility of a constructed fill, frost heave tests should be run on re-compacted and then re-consolidated specimens or on reconstituted specimens.
  3. The frost susceptibility test in the laboratory is a frost heave test. If the risk of thaw weakening is to be tested, a California Bearing Ratio test should be carried out after thawing of the specimen. The re-compacted or reconstituted specimen should be subjected to one or more freeze-thaw cycles before testing.
5.5.10.3 Evaluation of test results
  1. The results should be interpreted as a function of the type of construction work, the rules used in design and the available comparable experience, considering the consequence of the frost effects.

5.6 Chemical testing of soil and groundwater

5.6.1 Requirements for all chemical tests

5.6.1.1 Scope
  1. Although the detailed chemical composition of soil is often of limited interest for civil engineering purposes, the presence of certain chemical constituents in soil can be very significant, for example for the durability of the geotechnical structure. 68
  2. Routine chemical testing in a soil laboratory is usually limited to organic content (loss on ignition, total organic content, organic matter), carbonate content, sulfate content, pH value (acidity or alkalinity) and chloride content. This standard deals with these five chemical tests only.

    NOTE 1 Annex N provides more details on each chemical test and its interpretation, and some guidelines.

    NOTE 2 There are other chemical components that may cause an environment very aggressive to steel and concrete, for example sulfide, magnesium and ammonium. The corresponding chemical testing is not covered in this standard.

    NOTE 3 Corrosiveness to steel constructions in soil is usually evaluated by means of electrical resistivity tests and determination of the redox potential (not covered in this standard), pH, chlorides and sulfate determinations.

5.6.1.2. Objective
  1. The purpose of the chemical tests described herein is to classify the soil and to assess the detrimental effect of the soil and groundwater on concrete, steel and the soil itself. The tests are not intended for environmentally related purposes.
5.6.1.3 Requirements
  1. P The following requirements shall be specified for all chemical tests:
  2. P The proper procedures of mixing, riffling and quartering shall be strictly followed in order to avoid inconsistent results.
  3. Disturbed soil samples may be used for the chemical tests, but particle size and water content need to be representative of the field conditions (Quality Classes 1 to 3).
  4. For the determination of organic content, the particle size distribution only needs to be representative (Quality Class 4).

    NOTE Recommended test procedures are available in Annex N.

5.6.1.4 Evaluation of test results
  1. P The test results shall be reviewed together with the geological description and the prevailing environment.
  2. P Where appropriate, account shall be taken of recognised classifications in terms of the parameter measured.
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5.6.2 Organic content determination

5.6.2.1 Objective
  1. Organic content tests are used to classify the soil. In soil with little or no clay particles and carbonate content, the organic content is often determined from the loss on ignition at a controlled temperature. Other suitable tests can also be used. For example, organic content can be determined from the mass loss on treatment with hydrogen peroxide (H2O2), which provides a more specific measure of organics.
  2. The presence of organic matter can have undesirable effects on the engineering behaviour of soil. For example, the bearing capacity is reduced, the compressibility is increased, swelling and shrinkage potential is increased due to organic content. Gas can lead to large immediate settlements and can affect the consolidation coefficients and shear strength derived from laboratory tests. Organic matter is detrimental for the stabilisation of soil used for roads and is usually associated with low pH and at times with presence of sulfates which can have negative effects on foundations.
5.6.2.2 Requirements
  1. P For each test or series of tests, in addition to the list in 5.6.1.3, the following shall be specified:
  2. P Non-homogeneous samples require larger specimens and the appropriate apparatus. Correspondingly larger crucibles shall be used.
  3. P The loss on ignition shall be reported as a percentage of original dry matter, also giving the drying temperature, ignition temperature and drying and ignition times.
  4. P The organic content shall be reported as a percentage of original dry matter, also giving the method of determination.
5.6.2.3 Evaluation of test results
  1. In clays and silty soil with moderate organic content, the errors involved in the correction for bound water or carbonates can be so large that special testing methods are necessary.
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5.6.3 Carbonate content determination

5.6.3.1 Objective
  1. The carbonate content is used as an index to classify natural carbonate soil and rock or as an index to indicate the degree of cementation.
  2. Measurement of the carbonate content depends on the reaction with hydrochloric acid (HCl) which liberates carbon dioxide. It is usually assumed that the only carbonate present is calcium carbonate (CaCO3). The carbonate content is calculated from the content of carbon dioxide measured on treatment of the soil with HCl.
5.6.3.2 Requirements
  1. P The soil shall be assessed visually before the selection of the appropriate pre-treatment.
  2. When appropriate, large initial samples can be used to cope with non-homogeneous carbonate distribution in soil and rock. Representative test samples can be established by crushing and riffling.
  3. P The carbonate content shall be reported as a percentage of the original dry matter.
5.6.3.3 Evaluation of tests results
  1. P Some carbonates, e.g. dolomite, need not dissolve using the standard solution of hydrochloric acid during the specified time. Special methods shall be used for soil or rock types containing such carbonates.

5.6.4 Sulfate content determination

5.6.4.1 Objective
  1. The objective of the test is to determine the sulfate content as an index for the possible detrimental effect of the soil on steel and concrete. All naturally occurring sulfates, with rare exceptions, are soluble in hydrochloric acid. Some are soluble in water.
  2. The acid-soluble sulfate content is referred to as the total sulfate content, as distinct from the water-soluble sulfate content. It is important to appreciate which value is relevant.
  3. Groundwater containing dissolved sulfates, especially sodium and magnesium sulfates, can attack concrete and other materials placed in the ground or on the ground surface. Classification of soil and groundwater in terms of sulfate content is therefore necessary so that suitable precautionary measures can be taken, if required.
5.6.4.2 Requirements
  1. P It shall be specified for each test or group of tests, whether acid- or water-soluble sulfate is required for the test, in addition to the items listed in 5.6.1.3.
  2. P Non-homogeneous soil containing visible crystals of gypsum require large samples, which shall be crushed, mixed and riffled to provide representative test specimens. A visual assessment is needed before selecting the appropriate specimen preparation method.
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5.6.4.3 Evaluation of test results
  1. P The content in SO32− or SO42− shall be reported as a percentage of dry substance or in grams per litre, relating to acid- or water-soluble sulfate.

5.6.5 pH value determination (acidity and alkalinity)

5.6.5.1 Objective
  1. The pH value of groundwater or solution soil in water is used to assess the possibility of excessive acidity or alkalinity.
5.6.5.2 Requirements
  1. P The following shall be specified for each test or group of tests, in addition to the general requirements for chemical testing:
  2. P Standard buffer solutions shall be used for calibration of the pH meter.
  3. P The pH value of the soil suspensions or the groundwater shall be reported. The test method shall be stated.
5.6.5.3 Evaluation of test results
  1. The evaluation should consider that, in some soil, the measured values can be influenced by oxidation.

5.6.6 Chloride content determination

5.6.6.1 Objective
  1. The objective of the test is the determination of the water-soluble or acid-soluble chloride content so that the salinity of the pore water or soil can be assessed. The results provide an index for the possible effect of the groundwater towards concrete, steel, other materials and soil.
5.6.6.2 Requirements
  1. P The following shall be specified for each test or group of tests, in addition to the items listed in 5.6.1.3:
  2. P After drying, the soil shall be mixed thoroughly to redistribute any salts which may have migrated to form a surface crust.
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5.6.6.3 Evaluation of test results
  1. P The chloride content in grams per litre or as a percentage by dry mass of the soil shall be reported. The test procedures used shall state whether water-soluble or acid-soluble chlorides have been determined.

5.7 Strength index testing of soil

5.7.1 Objective

  1. The purpose of strength index tests is to determine in a rapid and simple manner the undrained shear strength cu of clayey soil.
  2. This standard covers the following strength index tests:

5.7.2 Requirements

  1. P The tests shall be performed on undisturbed specimens of quality class 1.

    NOTE 1 Further information on a procedure, presentation and evaluation for strength index testing can be found in CEN ISO/TS 17892-6, (see X.4.3).

    NOTE 2 Annex O gives information on the strength index tests considered and a checklist on the test procedures for the tests.

5.7.3 Use of test results

  1. It should be considered that the values of cu represent the undrained shear strength of the soil at its state in the laboratory. They need not represent the undrained strength of the soil in-situ.
  2. Depending on the characteristics of the soil and on the particular strength index test selected, the test results can be only an approximate estimate of cu.
  3. Strength index tests should only be used for design where well-documented, comparable experience with similar soil exists.
  4. If well-documented, comparable evidence exists, the undrained shear strength derived from the strength index tests may be used if the sample analytical method of EN 1997-1:2004, D.3 is applied.
  5. The test results may be used to check variability of undrained shear strength within a stratum.

5.8 Strength testing of soil

5.8.1 Objective and scope

  1. The objective of the test is to establish the drained and/or undrained shear strength parameters.
  2. The following strength tests are covered: 73
  3. Translational and ring shear box tests should be used for testing soil under drained conditions.

    NOTE Under quick strain rate, clays of very low permeability may sometimes be considered loaded undrained in both types of the shear box apparatus. The test then gives an indication of the undrained strength.

  4. In this section, only strength tests on fully saturated or dry soil are dealt with.

5.8.2 General requirements

  1. For the determination of the shear strength of clay, silt and organic soil, undisturbed samples (Quality Class 1) should be used. For certain soil or special purposes, tests can be carried out on reconstituted or remoulded specimens.
  2. For coarse silts and sands, the test specimens may be re-compacted or reconstituted. Care should be taken to select a preparation method that reproduces as closely as possible the structure and density relevant for the design at hand.
  3. P For re-compacted or reconstituted specimens, the composition, density and water content of the prepared specimens relevant for the in-situ conditions and the specimen preparation method shall be specified.
  4. P For a strength test, the following shall be evaluated or specified:
  5. The shear strength of a sample should be determined by a set of three or more tests under different normal stresses.
  6. P When determining the shear strength of a soil stratum, the following shall be taken into account: 74
  7. If samples of Quality Class 2 are tested, the effects of the sample disturbance should be considered in the interpretation of the results.

    NOTE Annex P provides a guideline for the minimum number of samples and tests for one stratum, as well as additional information on the test and its evaluation.

5.8.3 Evaluation and use of test results

  1. P The presentation of the test results shall include, where applicable:

    NOTE Linear extrapolation of the test results can give erroneous values of the strength of the soil as the failure envelope is generally not a straight line, especially at low normal stresses.

  2. P The stress range over which the strength parameters have been determined shall be given.
  3. There are several methods to obtain the stress-strain and strength parameters of soil in the laboratory and in-situ. If appropriate, the results from these different tests should be compared when evaluating the test results.
  4. The results should be evaluated taking into account the strain rate used for testing.
  5. The compression and direct shear tests provide commonly accepted strength parameters which may be applied to routine design methods, but which are not necessarily applicable to other analyses.
  6. It should be considered that unconfined compression and unconsolidated, undrained compression tests need not represent the undrained strength of the soil in-situ.

5.8.4 Unconfined compression test

5.8.4.1 Requirements
  1. The unconfined compression test should be carried out on specimens of soil of sufficiently low permeability to maintain undrained conditions during the test.
  2. Delays between trimming and testing should be avoided to prevent change of water content of specimens.

    NOTE Further information on a procedure, presentation and evaluation for the unconfined compression test can be found in CEN ISO/TS 17892-7, (see X.4.4.1).

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5.8.4.2 Evaluation and use of test results
  1. The test result is the approximate value of the unconfined compressive strength of the tested soil.
  2. The undrained shear strength cu may be determined as one half of the measured unconfined compressive strength.
  3. The effective stresses within the laboratory specimen may deviate from the effective stresses in-situ. The test result need not represent the undrained strength of the soil in-situ due to this difference.

5.8.5 Unconsolidated, undrained triaxial compression test

5.8.5.1 Requirements
  1. P The test shall be carried out without allowing any drainage from the specimens.
  2. P During preparation and testing, soil specimens shall not be given access to water (e.g. from the drainage leads or pore pressure transducers, etc.).
  3. P Water content before and after the test and bulk density before the test shall be determined for each specimen.

    NOTE Further information on a procedure, presentation and evaluation for the unconsolidated undrained triaxial compression test can be found in CEN ISO/TS 17892-8, (see X.4.4.2).

5.8.5.2 Evaluation and use of test results
  1. The test result is the undrained shear strength cu of the tested soil.
  2. The effective stresses within the laboratory specimen may deviate from the effective stresses in-situ. The test result need not represent the undrained strength of the soil in-situ due to this difference.

5.8.6 Consolidated triaxial compression test

5.8.6.1 Requirements
  1. P The tests shall be performed on undisturbed specimens of quality class 1.

    NOTE Further information on a procedure, presentation and evaluation of the consolidated triaxial compression test can be found in CEN ISO/TS 17892-9, (see X.4.4.3).

  2. P For a consolidated triaxial compression test, the following shall be evaluated or specified further to 5.8.2: 76
  3. P For consolidated, undrained triaxial tests, the requirements on measuring pore pressures, and the total stress path for shearing, shall be specified.
  4. P For consolidated drained tests, the volume change measurement device and the stress path for shearing shall be specified.
  5. P Water content before and after the test and bulk density before the test shall be determined for each specimen.
  6. One consistency limit determination and particle size analysis should be made per set of triaxial tests in one stratum.
  7. P The results shall clearly state the type of test that was carried out, which strength parameters are given, the shearing rate and the failure criterion used to select the shear strength (e.g. peak deviator stress, maximum stress ratio).
  8. P The report shall indicate any known deviation from the standard testing procedure, for example in the degree of saturation of the test specimens, testing procedures, composition of the specimen or in any other aspect.
  9. In conformity to 2.4.2.3 (4), more advanced laboratory strength tests, such as triaxial extension tests, simple shear tests, plane strain compression and extension tests, true triaxial tests, directional shear tests, all with the possibility of anisotropic instead of isotropic consolidation, should be considered.
5.8.6.2 Evaluation and use of test results
  1. The evaluation of the test results should take into account that undrained shear strength, pore pressure parameters and stress-strain relationships are affected by sample disturbance to a greater extent than the drained strength parameters.

    NOTE Reliable stress-strain modulus values, especially in the case of stiff soil, can only be obtained from advanced tests with special procedures to measure strains and axial force accurately (see 5.9).

  2. Depending on the type of test, drained or undrained strength of the soil may be derived. Accordingly, the values are effective angle of shearing resistance (φ′) and effective cohesion (c′), or undrained shear strength (cu).
  3. The values can be used in both drained and undrained stability analyses

    NOTE See EN 1997-1:2004, Annex D.

5.8.7 Consolidated direct shear box tests

5.8.7.1 Requirements
  1. P The tests shall be performed on undisturbed specimens of Quality Class 1.

    NOTE Further information on a procedure, presentation and evaluation of the consolidated direct shear box test can be found in CEN ISO/TS 17892-10, (see X.4.4.4).

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  2. P The location and orientation of the specimen shall be considered carefully so as to duplicate as closely as possible the in-situ conditions. In the translational shear box and ring shear tests, failure is forced to occur on or near a horizontal plane in the middle of the test specimen.
  3. P Negative or positive pore water pressures due to shear shall be avoided during the test as they cannot be measured and accounted for in the interpretation of the test. To maintain drained conditions, the rate of shearing shall be slow enough so that pore water pressures may dissipate.
5.8.7.2 Establishment and use of values
  1. The results of standard shear box tests represent the strength under drained conditions. The values are effective angle of shearing resistance and effective cohesion (see NOTE in 5.8.1 (3)).
  2. The values can be used in stability analyses.

    NOTE See EN 1997-1:2004, Annex D.

5.9 Compressibility and deformation testing of soil

5.9.1 General

  1. This standard covers the requirements for measurement of deformation characteristics of soil in the triaxial apparatus and the oedometer.

5.9.2 Oedometer compressibility testing

5.9.2.1 Objective
  1. In the oedometer, the cylindrical specimen is confined laterally, and is subjected to discrete increments of vertical axial loading or unloading and allowed to drain axially. Oedometer compression and swelling tests and evaluation of the collapse potential of a soil are covered.
  2. Alternatively, a test with continuous loading (constant rate of strain) may be carried out.
  3. The objective of the oedometer incremental compression and swelling tests is to determine the compression, consolidation and swelling characteristics of soil.
  4. The objective of the collapse potential test is to establish compressibility parameters for the soil in its unsaturated state, and to evaluate the additional compression upon inundation due to structural collapse of the soil.
5.9.2.2 Requirements
  1. P For the determination of the compressibility of a stratum of clay, silt or organic soil, undisturbed samples (Quality Class 1) shall be used.

    NOTE Small strain moduli of soil (e.g. moduli at less than 1 % strain for soft to medium clays) are very sensitive to all perturbations during sampling. According to 3.4.3 (3)P, specific sampling equipment and methods may be used, for example block sampling or stationary piston sampling or any other method known to give the best results for the soil to be tested.

    78
  2. P For re-compacted specimens, the composition, density and water content of the prepared specimens relevant to the in-situ conditions and the specimen preparation method shall be specified.
  3. P When determining the compressibility characteristics of a soil stratum, the following items shall be taken into account:
  4. Carrying out alternative tests to the incremental oedometer test, for example constant rate of strain oedometer tests, may be considered.
  5. P The initial vertical stress shall not exceed the in-situ vertical effective stress.

    NOTE For example for strain-softening clays, an initial stress of one fourth of the in-situ vertical effective stress can be considered an appropriate value.

  6. In a compression test, the highest vertical stress applied should be well in excess of the maximum effective vertical stress likely to occur in-situ. In a swelling test, the range of decrements of vertical stress to be applied during the test should include the range of stresses likely to be applied in-situ.
  7. P When testing the collapse potential, the test specimens shall be selected with adequate consideration of existing knowledge on the behaviour of the soil when subjected to inundation. The stress on the specimen at which inundation is applied shall be related to the range of vertical stresses likely to occur in-situ.

    NOTE 1 Further information on a procedure, presentation and evaluation of Oedometer compressibility testing can be found in CEN ISO/TS 17892-5, (see X.4.5).

    NOTE 2 Annex Q provides a guideline for the minimum number of samples and tests for one stratum, as well as additional information on the lest and its evaluation.

5.9.2.3 Evaluation and use of test results
  1. The oedometer test results may be used to estimate the yield stress (pre-consolidation pressure) for clays, organic soil and silty soil.
  2. It should be taken into account that the pre-consolidation pressure determined by the oedometer test can be greatly affected by sampling disturbance.
  3. Image The most common values to characterise compressibility are the oedometer modulus (Eoed), the coefficient of compressibility (mv), the compression index (Cc) and the pre-consolidation pressure (σp). Unloading and recompression can be represented by the swelling index (Cs). All these quantities are derived directly from the appropriate parts of the test curves. Image 79
  4. Settlements due to creep can be computed using the coefficient of secondary compression (Cα).
  5. The coefficient of consolidation cV can be derived using the one-dimensional consolidation theory.
  6. Any parameter in 5.9.2.3 (3) can be used for simple analyses of the settlement of spread foundations.
  7. If sample methods are applied, the oedometer modulus may be used.

    NOTE Examples of such sample methods are given in EN 1997-1:2004, F.1 and F.2

5.9.3 Triaxial deformability testing

5.9.3.1 Objective
  1. The objective of the triaxial deformability testing of soil is to determine the deformation moduli (stiffness parameters).
  2. Depending on the loading path, various stiffnesses can be measured.
  3. According to the drainage conditions, drained or undrained moduli E′ or Eu can be determined.
  4. Due to the non-linearity of soil behaviour, various moduli, e.g. tangent and/or secant moduli, may be defined at different stress or strain levels.
5.9.3.2 Requirements
  1. P For the determination of the stiffness of a stratum of a soil, undisturbed samples (Quality Class 1) shall be used.

    NOTE Small strain moduli of soil (e.g. moduli at less than 1 % strain) are very sensitive to all perturbations during sampling. According to 3.4.3 (3)P, specific sampling equipment and methods may be used, for example block sampling or stationary piston sampling or any other method known to give the best results for the soil to be tested.

  2. P A special instrumentation capable of measuring stresses and strains with high resolution shall be used for stiffness determination at strain levels below 0,1 %.

    NOTE For determination of very small strain moduli, the techniques based on propagation of shear waves or other dynamic methods can be used.

  3. P When determining the stiffness characteristics of a soil stratum, the following items shall be considered:
5.9.3.3 Evaluation and use of test results
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  1. The stiffness may be characterised by a complete curve, or by conventional values. For example, by the initial Young’s modulus of elasticity (E0), or by the E50 corresponding to 50 % of the maximum shear stress, etc.
  2. Young’s modulus and stress-strain curves of soft, normally consolidated soil may in some cases be determined from the standard triaxial strength tests.

5.10 Compaction testing of soil

5.10.1 Scope

  1. This standard covers compaction tests (Proctor tests) and the California Bearing Ratio test.

    NOTE Annex R provides a guideline for the minimum number of samples to be tested for one stratum, as well as additional information on the test and its evaluation.

5.10.2 Compaction tests

5.10.2.1 Objective
  1. Soil compaction tests (Proctor tests) are used to determine the relationship between dry density and water content when a given compaction effort is applied.
5.10.2.2 Requirements
  1. P The following shall be specified or checked:
  2. The option of carrying out in-situ tests instead of laboratory tests should be considered for special types of soil.
5.10.2.3 Evaluation and use of test results
  1. P The compaction characteristics of soil shall be reported together with grain size distribution curves and proportion of oversize material by dry mass with correction, if appropriate.
  2. The optimum water content (wopt) and the corresponding maximum dry density achieved under the applied compaction effort (ρd,max) can be used in evaluating the quality of compacted fills.

5.10.3 California Bearing ratio (CBR) test

5.10.3.1 Objective
  1. The objective of the test is to determine the California Bearing Ratio (CBR) of a compacted or undisturbed sample. 81
  2. The CBR value is obtained as the percentage of the standard load corresponding to the standard penetration, when a cylindrical plunger of a standard cross-sectional area is made to penetrate into the soil material.
5.10.3.2 Requirements
  1. P The following shall be specified or checked:
5.10.3.3 Evaluation and use of test results
  1. P The CBR test results shall be reported together with grain size distribution and proportion of oversize material by dry mass, if relevant.
  2. The CBR value can be used as a basic parameter for the design of flexible pavements. It can be used to evaluate the potential strength of sub-grade, sub-base and base course materials (including recycled materials) for supporting road, railways and airfield pavements.

5.11 Permeability testing of soil

5.11.1 Objective

  1. The objective of the test is to establish the coefficient of permeability (hydraulic conductivity) for water flow through water-saturated soil.

5.11.2 Requirements

  1. P When determining the coefficient of permeability of a soil stratum, the following items shall be considered:

    NOTE Further information on a procedure, presentation and evaluation of the permeability test can be found in CEN ISO/TS 17892-1 1, (see X.4.7).

  2. P Depending on the conditions where the test results will be used, the following shall be specified:
    1. In clay, silt and organic soil: 82
      • – the stress conditions under which the specimen is to be tested;
      • – the criterion for achieving and maintaining the steady-state flow condition;
      • – the direction of flow through the specimen;
      • – the hydraulic gradient under which the specimen is to be tested;
      • – the need for back-pressure and the required degree of saturation;,
      • – the chemistry of percolating fluid.
    2. In sand and gravel:
      • – the density index to which the specimen is to be prepared;
      • – the hydraulic gradient under which the specimen is to be tested;
      • – the need for back-pressure and the required degree of saturation.
  3. The hydraulic gradient in the laboratory should be close to that in the field, unless otherwise required due to a particular problem.
  4. P When selecting the hydraulic gradient, it shall be checked that the gradient in the laboratory test and the gradient in-situ lie within the domain of application of Darcy’s law.
  5. The report should indicate any known deviation from the standard testing procedure, for example in the degree of saturation of the test specimens, testing procedures, composition of the specimen or in any other aspect.
  6. For permeability tests on clay, silt or organic soil, only soil specimens of Quality Classes 1 or 2 should be used.
  7. For sand and gravel materials, specimens of Quality Class 3 and remoulded or re-compacted soil samples may be used.
  8. It should be checked that the volume changes due to the consolidation of the specimen shall only negligibly affect the measured permeability.

    NOTE Annex S provides a guideline for the minimum number of samples and tests for one stratum, as well as additional information on the test and its evaluation.

5.11.3 Evaluation and use of test results

  1. The evaluation should assess:
  2. For partially saturated soil, much smaller values may be relevant than the values measured in the case of full saturation.
  3. Due consideration should be given to whether a temperature correction should be applied.
  4. The coefficient of permeability can be computed from the test data under the assumption that Darcy’s law is valid. 83
  5. The coefficient of permeability can be used in design of excavations and earth dams to estimate the amount of seepage, to assess the feasibility of groundwater level management (lowering), to design the sheet pile walls, to estimate seepage pressures, etc.

5.12 Tests for classification of rocks

5.12.1 General

  1. The following tests are included in this standard:
  2. Classification relates to the division of identified rock into specific types defined for particular civil engineering purposes. The classification is related to mineralogical components, structure, induration, rock density, water content, porosity and rock strength.

    NOTE Annex U provides more details and guidelines on the classification tests.

5.12.2 Requirements for all classification tests

  1. P The classification test results shall be reviewed together, compared with drilling logs, corresponding geophysical logs, photographs of cores and comparable experience.
  2. The soil and rock classification should be compared with available geological background information in order to provide an engineering geological model.
  3. Geological maps should be used as a guide for the classification of rock and rock masses, whenever available.
  4. Second opinion evaluations and the use of typical examples with rock comparisons may be required in order to achieve a consistent description.

5.12.3 Rock identification and description

5.12.3.1 Objective and requirements
  1. The identification and description of rock material and mass are carried out on the basis of mineralogical composition, predominant grain size, genetic group, structure, weathering and other components. The description may be carried out on cores and other samples of natural rock and on rock masses in-situ.
  2. P The laboratory procedure shall conform to EN ISO 14689-1.
  3. More detailed description of rock may be applied. Then the following should be specified: 84
  4. Rock identification and description should be earned out on all samples received in the laboratory, regardless of rock homogeneity, as the identification and description constitutes the framework for all testing and evaluations.
5.12.3.2 Evaluation of results
  1. The classification of the rock mass using cores should be based on the highest possible core recovery to identify discontinuities and possible cavities.
  2. The disturbance of the core from the drilling process should be evaluated since most rock mass quality designations relate to the fractures found in the cores and their quality.

5.12.4 Water content determination

5.12.4.1 Objective and requirements
  1. P With the exception of rocks mentioned in 5.12.4.2 (2), water content of rock shall be determined by oven-drying at (105 ± 5) °C.
  2. P Measures shall be specified to retain water during sampling and storage, if relevant.
  3. P The following shall be specified:
  4. A minimum sample of at least 50 g or a core piece with a dimension of at least 10 times the maximum grain size of mineral components should be used.
  5. P The report shall state whether the measured water content corresponds to the in-situ water content.

    NOTE As no ISO/CEN standard for rock testing is currently available, the laboratory methods described in U.3, with reference to X.4.9.2 can be applied.

5.12.4.2 Evaluation of test results
  1. The results of the determination of the water content should be compared with the fully-saturated water content as a function of the density (or porosity) of the test specimen. Anomalous results should be investigated by repeated testing.
  2. Rock types with significant amounts of gypsum should be tested at 50 °C as the bound water may partly dehydrate at 105 °C.
  3. For rock types in which the pore water contains dissolved salts or rock types with closed pores, the reported water content should be evaluated in this respect.
  4. The water content should be used for correlation of strength and deformation characteristics of the rock types in boreholes and at test sites. 85
  5. Comparisons with available correlations of water content and rock type should be made.

5.12.5 Density and porosity determination

5.12.5.1 Objective and requirements
  1. The test is used to determine the bulk and dry density to obtain the porosity and related properties of a rock sample. The bulk and dry density is derived based on weight analyses provided reliable determination of the sample volume is available.
  2. The pore volume may be calculated based on the dry density and the particle density determined using methods as for soil, provided no closed pores exist in the rock specimen. Porosity is the ratio of pore volume to total volume.
  3. P The following shall be specified:
  4. A test specimen of at least 50 g, with a minimum dimension of 10 times the maximum grain size of the mineral components, should be tested.

    NOTE As no ISO/CEN standard for testing of rock is currently available, the laboratory methods described in U.4 with reference to the bibliography in X.4.9.3 can be applied.

5.12.5.2 Evaluation of test results
  1. Image The density and porosity should be integrated in the reporting of rock description and established strength and deformation characteristics of the rock types in boreholes and at test sites. Image
  2. The density and porosity results should be used for comparison of rock strength and deformation properties and to establish correlations for the different rock types.
  3. The existence of closed pores can influence the porosity. The determination of the total pore volume should be based on the density of solids of a powdered sample.

    NOTE Further information on a procedure, presentation and evaluation of density and porosity determination can be found in CEN ISO/TS 17892-3, (see X.4.9.3).

5.13 Swelling testing of rock material

5.13.1 General

  1. This standard deals with the following tests for determination of swelling potential exposed to wetting and drying or unloading in an aqueous environment:

    NOTE Some rock materials, notably those with high clay content, are prone to swelling, weakening and disintegration when exposed to wetting and drying or unloading in an aqueous environment. The index tests provide an indication to estimate swelling properties under well-controlled conditions. The tests are usually done on softer rock materials like claystone and shale. The tests can be used for the characterization of harder rocks subjected to weathering.

  2. Rocks that disintegrate during the tests should be further classified using relevant soil classification tests such as the shrinkage, liquid and plastic limits, particle size distribution and the type and content of clay minerals.

    NOTE Annex V provides more details on each of the swelling tests and their interpretation as well as some guidelines.

5.13.2 General requirements

  1. The specimens should conform closely to the practice recommended for right cylinders or for rectangular prisms. The sample size should allow for preparation of test specimens by re-coringand/or machining in a lathe, with the axis for one direction of the swell measurement perpendicular to a bedding or foliation.

    NOTE For recommendations for right cylinders and rectangular prisms, see X.4.8.

  2. P The following shall be specified:

5.13.3 Evaluation of test results

  1. P The results shall be reviewed in the light of the description, and classification parameters shall be established.
  2. The value used in design derived from laboratory tests should be compared with field experience with comparable rock types under similar climatic, loading and wetting conditions.
  3. The short and especially long term weathering processes of swelling, weakening or disintegration due to wetting and drying may only be partly mirrored by the laboratory tests, even for similar conditions of loading and water content, because of the influence of among others natural fissuring, stress, drainage and pore water chemistry.

5.13.4 Swelling pressure index under zero volume change

5.13.4.1 Objective and requirements
87
  1. The test is intended to measure the pressure necessary to constrain an undisturbed rock specimen at constant volume when immersed in water.
  2. The test may be used to estimate the swell pressure in-situ by comparison of documented experience for the rock stratum.
  3. P The test specimen shall be cored using Category A sampling methods.

    NOTE The test can be carried out following the recommendation given in V.2.

5.13.4.2 Evaluation of test results
  1. P The applied force to maintain the condition of zero volume change shall be corrected for the deformation in the test cell system itself (ball bearings and bedding of filter stones towards the end platens).
  2. The maximum swell pressure under zero volume change should be used as an upper limit of swell pressure under the specified laboratory conditions.
  3. Before the laboratory-determined maximum swell pressure is used in design, field evidence should be taken into consideration related to short and especially long term weathering processes of swelling, weakening or disintegration due to wetting and drying, loading conditions, water content and pore water chemistry.

5.13.5 Swelling strain index for radially-confined specimens with axial surcharge

5.13.5.1 Objective and requirements
  1. The test is intended to measure the axial swelling strain developed against a constant axial surcharge, when a radially confined, undisturbed rock specimen is immersed in water.
  2. P The test specimen shall be cored using Category A sampling methods.

    NOTE The test can be carried out following the recommendation given in V.3.

5.13.5.2 Evaluation of test results
  1. P The measured strain under the applied force during the test stages shall be corrected for the deformation in the test cell system itself (ball bearings and bedding of filter stones towards the end platens).
  2. The axial swelling strain under constant axial surcharge should be used to estimate the swell potential in-situ taking into account the documented experience for the rock stratum.
  3. Depending on the applied vertical stress, the test provides background for the evaluation of the vertical heave or the lateral deformation of a rock/structure interface.
88

5.13.6 Swelling strain developed in unconfined rock specimen

5.13.6.1 Objective and requirements
  1. The test is intended to measure the swelling strain developed when an unconfined undisturbed rock specimen is immersed in water.
  2. P The test shall only be applied to specimens prepared from at least category B sampling methods that do not change their geometry appreciably during testing.
  3. It is advised that slaking, less durable, rocks should be tested using a confined swelling test.

    NOTE The test may be carried out following the recommendation given in V.4.

  4. P The report shall clearly indicate that the specimen was not radially confined during the swelling test.
5.13.6.2 Evaluation of test results
  1. The test may be used to estimate the swell potential in-situ by comparison to documented experience for the rock stratum.
  2. Unconfined swelling strains and their directions with respect to bedding or foliation should be used only as an estimate of in-situ swelling potential.

5.14 Strength testing of rock material

5.14.1 General

  1. This standard includes five laboratory methods for determining the strength of rock:

    NOTE Annex W provides more detail on each strength test and its interpretation.

5.14.2 Requirements for all strength tests

  1. P The following shall be specified:

    NOTE Annex W provides a guideline for the minimum number of test specimens to be tested for one formation for uniaxial compression tests, Brazil tests and triaxial tests for projects of geotechnical category 2 with respect to standard deviations of measured strength and comparable experience.

89

5.14.3 Evaluation of test results

  1. The evaluation of the test results should include comparison with recognised databases to help screen the data for anomalous results, while accounting for the natural range in compressive strength and deformation parameters in rock, and correlations with the results of classification tests.
  2. All test results should be grouped and analysed with respect to the geological description and classification properties using statistical methods when appropriate.
  3. The values can be used to evaluate in-situ strength and deformation properties and to classify rock element and rock mass properties.

5.14.4 Uniaxial compression and deformability test

5.14.4.1 Objective and requirements
  1. The uniaxial compression test measures the compressive strength, the Young’s modulus of elasticity and Poisson’s ratio of cylindrical test specimens of rock.
  2. The test is intended for classification and characterisation of intact rock.
  3. P The following shall be specified in addition to the requirements in 5.14.2:
  4. P The test specimens shall be prepared from cores taken with Category A sampling.
  5. Recommendations for testing of the uniaxial compression strength and deformability should be followed.

    NOTE Recommendations for such tests are given in Annex W.

5.14.4.2 Evaluation of test results
  1. The uniaxial compression strength should be determined as the maximum vertical stress obtained during the compression test.
  2. The modulus of elasticity defined as the ratio of the axial stress change to axial strain produced by the stress change should be determined using one of the three definitions below: 90
  3. The Poisson’s ratio should be determined as the slope of the radial strain versus axial strain curve.
  4. Young’s elasticity modulus and Poisson’s ratio should be calculated within the same interval of vertical stress.
  5. Test results should be evaluated with respect to rock classification properties and the rupture pattern illustrated by a sketch of the tested rock specimen.
  6. The unconfined compression strength (σC) can be used as a classification parameter for the intact rock quality and it could be used in combination with triaxial compression test results in a Mohr diagram to define the Mohr-Coulomb rupture parameters angle of shearing resistance (φ) and cohesion (c).

    NOTE Young’s modulus of elasticity E and Poisson’s ratio v may be used for settlement calculation according to EN 1997-1:2004, Annex F.

5.14.5 Point load test

5.14.5.1 Objective and requirements
  1. The point load test is intended as a strength index test for the classification of rock materials. The test results can also be used for estimating the strength of a group of rocks of the same range of competence.
  2. The point load test is not a direct way to measure rock strength but an index test. The correlation between point load test results and strength should be documented in each case.
  3. P In addition to the requirements in 5.14.2 (1)P, the testing methods with reference to cores, blocks and irregular lumps shall be specified.
  4. P The test specimens shall be prepared from cores taken with Category A sampling.
  5. Test specimens of blocks and irregular lumps taken in pits may be used provided this is reported accordingly and the rock specimens are taken using Category B sampling.
  6. Recommendations for the point load test should be followed.

    NOTE Recommendations for such a test are given in W.2.

5.14.5.2 Evaluation of test results
  1. P Because of large variability, the evaluation of rock characterisation and predictions of other strength parameters shall be based on a statistical approach. From test data consisting of at least 10 single tests, the two highest and two lowest values shall be deleted before calculating the mean from the remaining.
  2. In order to classify samples or strata using a mean value of Point Load Strength Index, the minimum number of tests should be five. 91
  3. The test measures the Point Load Strength Index of rock specimens, and their Strength Anisotropy Index, which is the ratio of the Point Load Strengths in directions which give the greatest and least values.

5.14.6 Direct shear test

5.14.6.1 Objective and requirements
  1. The direct shear test measures peak and residual direct shear strength as a function of the stress normal to the plane of shearing.
  2. This standard deals with the laboratory testing for the determination of the basic shear strength parameters and the surface characteristics of a discontinuity that controls the shear strength.
  3. If the surface characteristics of a discontinuity that controls the shear strength are determined, an accurate description should be made, including type and roughness of the joint, type and thickness of fill material, and the presence of water in the joint.
  4. P The following shall be specified in addition to the requirements in 5.14.2 (1)P:
  5. P The test specimens shall be prepared from cores taken with category A sampling or from blocks taken in a pit using at least Category B sampling.
  6. Recommendations for direct shear tests should be followed.

    NOTE Recommendations for such a test are given in W.3.

5.14.6.2 Evaluation of test results
  1. The evaluation of test results of shear strength versus stress perpendicular to the rupture plane should include a study of the shearing plane in order to take into account bedding and schistosity, cleavage of the rock specimen, the interface properties between rock and concrete, or what was tested.
  2. Shear strength parameters angle of shearing resistance (φ) and cohesion (c) may be established using a number of shear tests on different specimens taken from a rock stratum using Mohr-Coulombs rupture criterion. Alternatively, residual parameters may be found using multiple testing with different normal stresses on an established rupture plane.
  3. The test measures the shear strength in a forced rupture plane under certain stresses perpendicular to the rupture plane. Peak and residual shear strength after some shear deformation can be established. Usually the rupture plan is intentionally established along a known discontinuity.
  4. The test is intended for strength classification and characterization of intact rock and should not be used without geological correlation and rock classification for field conditions.
92

5.14.7 Brazil test

5.14.7.1 Objective and requirements
  1. The Brazil test is intended to measure indirectly the uniaxial tensile strength of a cylindrical rock specimen.
  2. P The following shall be specified in addition to the requirements in 5.14.2 (1)P:
  3. P Due to the variability of the test results, duplicate testing of test specimens cut in parallel shall be performed.
  4. For shales and other anisotropic rock, it is recommended to cut test specimens parallel to and perpendicular to bedding. For specimens cut parallel to bedding, the direction of the load related to bedding should be specified.
  5. P The test specimens shall be prepared from cores taken with category A sampling.
  6. Recommendations for the Brazil test should be followed.

    NOTE Recommendations for such a test are given in W.4.

5.14.7.2 Evaluation of test results
  1. The evaluation of tensile strength should take into consideration that the presence of hidden weakness planes in the test specimen may disturb the result and the failure plane should be sketched after test and evaluated.
  2. The test provides an indirect determination of the tensile strength σT in a forced rupture plane.
  3. The tensile strength (σT) may be used as a classification parameter for the intact rock quality and it may be used in a Mohr diagram at a corresponding maximal stress σ1 together with Mohr circles from uniaxial or triaxial compression tests to define the Mohr-Coulomb strength parameters angle of shearing resistance (φ) and cohesion (c).
  4. The test is intended for strength classification and characterisation of intact rock and the test results should not be used without geological correlation and rock classification for field conditions.
93

5.14.8 Triaxial compression test

5.14.8.1 Objective and requirements
  1. The triaxial compression test is intended to measure the strength of cylindrical rock specimens subjected to triaxial compression. A number of tests provide the values necessary to determine the strength envelope in a Mohr-Coulomb diagram. From this envelope, the angle of shearing resistance and the cohesion intercept may be determined.

    NOTE No provisions are usually made for drainage of the pore water, nor for the measurement of pore water pressure. In certain rock types (e.g. shales and porous limestone and chalk) and under certain conditions, the pore water pressure may influence the results. For such rock types, advanced triaxial test systems allowing for measuring pore water pressure and volumetric strains are necessary. Such testing may include similar measuring techniques as used for uniaxial compressive strength according to W.1 .

  2. P In addition to the requirements in 5.14.2 (1)P, the test specimen orientation and dimensions, reflecting the testing method shall be specified.
  3. P The test specimens shall be prepared from cores taken with Category A sampling.
  4. Recommendations for triaxial compression testing should be followed.

    NOTE Recommendations for such tests are given in W.5.

5.14.8.2 Evaluation of test results
  1. A triaxial test consists of a series of compression tests earned out under different confining pressures in a triaxial cell. A strength envelope of confining pressures versus axial stress at rupture can be used to establish the Mohr-Coulomb strength parameters angle of shearing resistance (φ) and cohesion (c).
  2. The homogeneity of a series of test specimens to establish the test parameters should be evaluated based on the geological description and rock classification parameters.
  3. The determined strength parameters relate to intact rock. In-situ properties can only be established taking into account the upscaling from element testing of intact rock to the mass properties of the rock in-situ.
94

Section 6 Ground investigation report

6.1 General requirements

  1. P The results of a geotechnical investigation shall be compiled in the Ground Investigation Report which shall form a part of the Geotechnical Design Report.
  2. P The Ground Investigation Report shall consist of the following:
  3. The information may be presented as one report or as separate parts.
  4. The Ground Investigation Report may include derived values.
  5. P The Ground Investigation Report shall state known limitations of the results, if appropriate.
  6. The Ground Investigation Report should propose necessary further field and laboratory investigations, with comments justifying the need for this further work. Such proposals should be accompanied by a detailed programme for the further investigations to be carried out.

6.2 Presentation of geotechnical information

  1. P The presentation of geotechnical information shall include a factual account of all field and laboratory investigations.
  2. The factual account should include the following information, as relevant: 95
  3. P The presentation of geotechnical information shall include documentation of the methods, procedures and results including all relevant reports of:
  4. P The results of the field and laboratory investigations shall be presented and reported according to the requirements defined in the EN and/or ISO standards applied in the investigations.

6.3 Evaluation of geotechnical information

  1. P The evaluation of the geotechnical information shall be documented and include, as appropriate:
  2. P It shall be documented, if appropriate, that:
  3. The documentation of the evaluation of the geotechnical information should include as appropriate:
  4. Averaging can mask the presence of a weaker zone and should be used with caution. It is important that weak zones are identified. Variations in geotechnical parameters or coefficients can indicate significant variations in site conditions.
  5. The documentation should include comparisons of the specific results with experience for each geotechnical parameter, giving special consideration to anomalous results for a given stratum when compared with any results from other types of laboratory and field tests capable of measuring the same geotechnical parameter.
  6. The documentation of the evaluation should substantiate the following aspect: strata in which ground parameters differ only slightly may be considered as one stratum. 96
  7. A sequence of fine layers with greatly differing composition and/or mechanical properties may be considered as one stratum if the overall behaviour is relevant, and the behaviour can be adequately represented by ground parameters selected for the stratum.
  8. When deriving the boundary between different ground layers and the groundwater level, there may be interpolated linearly between the investigation points provided the spacing is sufficiently small and the geological conditions are sufficiently homogeneous. Such application of linear interpolations and their justification should be reported.

6.4 Establishment of derived values

  1. P If correlations have been used to derive geotechnical parameters or coefficients, the correlations and their applicability shall be documented.
97

Annex A
List of test results of geotechnical test standards

(Informative)

  1. In Table A.1, field and laboratory tests are listed together with the respective test results which should be presented in the Ground Investigation Report (if applicable).
Table A.1 — List of test results of geotechnical standards
Field testa Test results
CPT
  • – Cone penetration resistance (qc)
  • – Local unit side friction (fs)
  • – Friction ratio (Rf)
CPTU
  • – Corrected cone resitance (qt)
  • – Local unit side friction (fs)
  • – Measured pore pressure (u)
Dynamic probing
  • – Number of blows N10 for the following tests: DPL, DPM, DPH
  • – Number of blows (N10) or (N20) for the DPSH test
SPT
  • – Number of blows N
  • – Energy correction Er
  • – Soil description
Ménard pressuremeter test
  • – Pressuremeter modulus (EM)
  • – Creep pressure (pf)
  • – Limit pressure (pLM)
  • – Expansion curve
Flexible dilatometer test
  • – Dilatometer modulus (EFDT)
  • – Deformation curve
All other pressuremeter tests
  • – Expansion curve
Field vane test
  • – Undrained shear strength (uncorrected) (cfv)
  • – Remoulded undrained shear strength (crv)
  • – Torque-rotation curve
Weight sounding test
  • – Continuous record of weight sounding resistance
  • – Weight sounding resistance is:
    • – either the penetration depth for a standard load;
    • – or the number of half-turns required for every 0,2 m penetration, at the standard load of 1 kN
Plate loading test
  • – Ultimate contact pressure (pu)
Flat dilatometer test
  • – Corrected lift-off pressure (p0)
  • – Corrected expansion pressure (p1) at 1,1 mm
  • – Dilatometer modulus EDMT, material index (IDMT) and horizontal stress index (KDMT)
98
Laboratory testb Test results
Water content (soil)
  • – Value of (w)
Bulk mass density (soil)
  • – Value of (ρ)
Particle mass density (soil)
  • – value of (ρs)
Particle size distribution (soil)
  • – Grain size distribution curve
Consistency limits (soil)
  • – Plastic and liquid limit values (wP), (wL)
Density index (soil)
  • – Values of emax, emin and ID
Organic content (soil)
  • Image Loss on ignition Image (COM)
Carbonate content (soil)
  • – Value of carbonate content (CCaCO3)
Sulfate content (soil)
  • – Value of sulfate content (CSO42−) or (CSO32−)
Chlorite content (soil)
  • – Value of chlorite content (CCl)
pH (soil)
  • – Value of pH
Compressibility oedometer (soil)
  • – Compressibility curve (different options)
  • – Consolidation curves (different options)
  • – Secondary compression curve (creep curve)
  • – Values of Eoed (stress interval) and σp or Cs, Cc, σp
  • – Value of Cα
Laboratory vane (soil)
  • – Value of strength index (cu)
Fall cone (soil)
  • – Value of undrained shear strength (cu)
Consolidated triaxial compression(soil)
  • – Value of strength index (cu)
Unconfined compression (soil)
  • – Value of strength index qu = 2cu
Unconsolidated undrained compression (soil)
  • – Stress-strain curve(s) and pore pressure curve
  • – Stress paths
  • – Mohr circles
  • c’, φ’ or cu
  • – Variations of cu with σc
  • – Deformation parameter(s) (E’) or (Eu)
Consolidated direct shear box (soil)
  • – Stress-displacement curve
  • τ−σ diagram
  • c’ , φ
  • – Residual parameters
99
California bearing ratio (soil)
  • – Value of the CBR index (ICBR)
Permeability (soil)
  • – Value of the coefficient of permeability (k):
    • – from direct laboratory permeability test
    • – from field permeability tests
    • – from oedometer test
Water content (rock)
  • – Value of w
Density and porosity (rock)
  • – Value of ρ and n
Swelling (rock)
  • – Swelling Strain Index
  • – Swelling pressure
  • – Free swell
  • – Swell under constant load
Uniaxial compression and deformability (rock)
  • – Value of σC
  • – Value of deformation modulus (E)
  • – Value of Poisson’s ratio (v)
Point-load test (rock)
  • – Strength index Is50
Direct shear test (rock)
  • – Stress-displacement curve
  • – Mohr diagram
  • c’, φ
  • – Residual parameters
Brazil test (rock)
  • – Tensile strength (σT)
Triaxial compression test (rock)
  • – Stress-strain curve(s)
  • – Stress paths
  • – Mohr circles
  • c’, φ
  • – Values of deformation modulus (E) and Poisson’s ratio (v)
  1. See section 4.
  2. See section 5.
100

Annex B
Planning of geotechnical investigations

(Informative)

B.1 Stages of ground investigations in geotechnical design, execution of works and exploitation of the structure

Image

101
Table B.1— Example of the selection of ground investigation methods in different stages
Image Preliminary investigations Design investigations Control investigations

Desk study of topographical, historical, geological and hydrogeologicl maps

Mineral extraction

Aerial photo - interpretation

Archives of previous construction works and investigations

Site inspection

Preliminary geophysical surveys

Preliminary intrusive investigations

Fine soil

CPT, SS, DP,

SE

FVT or SPT

OS TP, PS, OS

GW

Coarse soil

SS, CPT, DP,

SR

SPT

AS, OS, TP

GW

Rock

SR, CPT, MWD

PLT

CS, AS, TP

GW

Preliminary choice of foundation method Preliminary choice of foundation method Preliminary choice of foundation method Pile foundation SS, CPT, DP, SR FVT, SPT, PIL PS, OS, CS, PMT GWC Verification of choice of foundation method and design procedure, control of ground improvement works and stability during construction PIL, Pile driving tests, Stress wave measurements GWC, settlements, Inclinometers
Shallow foundation SS or CPT, DP FVT, DMT or PMT, BJT PS, OS, CS, TP GWC

Check of the soil type Check of the stiffness (CPT) Settlements, Inclinometers, GWC Volume change potential due to water content change

Pile foundation CPT, DP, SR SPT, DMT, PIL OS, TP GWO PIL, Pile driving tests, Stress wave measurements GWC, settlements, Inclinometers
Shallow foundation CPT, DP SPT, PMT, BJT, DMT, PLT OS, TP GWO Check of the soil type Check of the stiffness (CPT, DP, SPT) Settlements
Pile or Shallow foundation SR, MWD, mapping of discontinuities RDT, PMT, BJT TP, CS GWO Check inclination and discontinuities in the rock and its surface Check contact between pile toe/ foundation and rock surface Verify water conditions of flow and pressure Image 102
Image Abbreviations  
Field, testing Sampling
BJT Borehole jack test PS Piston sampler
DP Dynamic probing CS Core sampler
SR Soil/rock sounding AS Auger sampler
SS Static sounding (e,g, weight sounding test, WST) OS Open sampler
CPT(U) Cone penetration test (with pore pressure recording) TP Test pit sampling
SPT Standard penetration test  
PMT Pressuremeter test  
DMT Dilatometer test Groundwater measurements
FVT Field vane test GW Groundwater measurements
PLT Plate load test GWO Groundwater measurements with open system
MWD Measuring while drilling GWC Groundwater measurements with closed system
SE Seismic measurements  
PIL Pile load test  
RDT Rock dilatometer test  
 

Notes:

Soil include naturally depoisted and anthropogenic depoists

Surveying and logging arc not included in this chart

Laboratory tests are not presented on this table Image

103

B.3 examples of recommendations for the spacing and depth of investigations

  1. The following spacing of investigation points should be used as guidance:
  2. For the investigation depth za the following values should be used as guidance. (The reference level for za is the lowest point of the foundation of the structure or structural element, or the excavation base.) Where more than one alternative is specified for establishing za, the one which yields the largest value should be applied.

    NOTE For very large or highly complex projects, some of the investigation points generally extend to greater depths than those specified under B.3 (5) to B.3 (13).

  3. Greater investigation depths should always be selected, where unfavourable geological conditions, such as weak or compressible strata below strata of higher bearing capacity, are presumed.
  4. Where structures under B.3 (5) to B.3 (8) and B.3 (13) are built on competent strata, the depth of investigation can be reduced to za = 2 m, unless the geology is indistinct, in which case at least one borehole should be taken down to a minimum of za = 5 m. If a bedrock formation is encountered at the proposed base of the structure, this should be taken as the reference level for za. Otherwise, za refers to the surface of the bedrock formation.
  5. For high-rise structures and civil engineering projects, the larger value of the following conditions should be applied (see Figure B.1 a)):

    where bF is the smaller side length of the foundation.

  6. For raft foundations and structures with several foundation elements whose effects in deeper strata are superimposed on each other:

    za ≥ l,5·bB

    where bB is the smaller side of the structure, (see Fig. B.1 b)).

    104

    Figure B.1 — High-rise structures, civil engineering projects

    Figure B.1 — High-rise structures, civil engineering projects

  7. Embankments and cuttings, the larger value of the following conditions should be met (see Figure B.2):

    Figure B.2 — Embankments and cuttings

    Figure B.2 — Embankments and cuttings

    1. For dams:
      • – 0,8h < za < l,2h
      • za ≥ 6 m

        where h is the embankment height.

    2. For cuttings:
      • za ≥ 2,0 m
      • za ≥ 0,4h

        where h is the dam height or depth of cutting.

    105
  8. Linear structures, the larger value of the following conditions should be met (see Figure B.3):

    Figure B.3 — Linear structures

    Figure B.3 — Linear structures

    1. For roads and airfields:

      za ≥ 2 m below the proposed formation level.

    2. For trenches and pipelines, the larger value of:
      • za ≥ 2 m below the invert level;
      • za ≥ l,5bAh

        where bAh is the width of excavation.

    3. Where relevant, the recommendations for embankments and cuttings should be followed.
  9. For small tunnels and caverns, (see Figure B.4):

    bAb < za < 2,0bAb

    where bAb is the width of excavation.

    The groundwater conditions described in (10) b) should also be taken into account.

    Figure B.4 — Tunnels and caverns

    Figure B.4 — Tunnels and caverns

  10. Excavations (see Figure B.5). 106
    1. Where the piezometric surface and the groundwater tables are below the excavation base, the larger value of the following conditions should be met:
      • za ≥ 0,4h
      • za ≥ (t + 2,0) m

      where

      t is the embedded length of the support; and
      h is the excavation depth.
    2. Where the piezometric surface and the groundwater tables are above the excavation base, the larger value of the following conditions should be met:
      • za ≥ (l,0H + 2,0)m
      • za ≥ (t + 2,0)m

      where

      H is the height of the groundwater level above the excavation base; and
      t is the embedded length of the support.

    Image If no stratum of low permeability is encountered down to these depths: Image zat + 5 m.

    Figure B.5 — Excavations

    Figure B.5 — Excavations

  11. For water-retaining structures, za should be specified as a function of the proposed level of impounded water, the hydrogeological conditions and the construction method.
  12. For cut-off walls (see Figure B.6): 107

    Figure B.6 — Cut-off wall

    Figure B.6 — Cut-off wall

  13. For piles (see Figure B.7), the following three conditions should be met:

    where

    DF is the pile base diameter; and
    bg is the smaller side of the rectangle circumscribing the group of piles forming the foundation at the level of the pile base.

    Figure B.7 — Pile groups

    Figure B.7 — Pile groups

108

Annex C
Example of groundwater pressure derivations based on a model and long term measurements

(Informative)

  1. The natural groundwater pressure is part of the hydrological cycle being influenced by the precipitation, evapotranspiration, snow melting, surface run-off etc.
  2. In order to establish a model of the groundwater situation for a building or a civil engineering project site and the surrounding area, available hydrogeological information should be compiled and compared to the actual groundwater measurements. Such information could be:
  3. The groundwater measurements for a project normally only contain a short series of measurements. In these cases it is important to make a prediction of the expected groundwater pressure for the actual design situation and site. Such a prediction can be based on the model mentioned above and on long term measurements of the groundwater in a similar aquifer in the same region as the project in combination with a short term measurement on the site.
  4. By using statistical methods, it became possible to predict the groundwater pressure within a few kPa based on 15 years measurements in a reference system and a 3 month measuring period on the actual site, see Figure Cl.
  5. It is also possible to simulate the groundwater fluctuations by a conceptual model. Precipitation and air temperature can be used as input in the model. The groundwater response is calibrated against long term measured groundwater fluctuations in the region.

    NOTE For additional information and examples, see X.2.

109

Figure C.1 — Measured and predicted groundwater levels

Figure C.1 — Measured and predicted groundwater levels

110

Annex D
Cone and piezocone penetration tests

(Informative)

D.1 Example for deriving values of the effective angle of shearing resistance and drained Young’s modulus

  1. Table D.1 is an example that can be used to derive values, from the value of qc, of the effective angle of shearing resistance (ϕ′) and drained (long term) Young’s modulus of elasticity (E′) for quartz and feldspar sands, for calculations of the bearing resistance and settlement of spread foundations.
  2. This example was obtained by correlating the mean value of qc in a layer to the mean values of ϕ′ and E′
    Table D.1 — An example for deriving values of the effective angle of shearing resistance (φ′) and drained Young’s modulus of elasticity (E′) for quartz and feldspar sands from cone penetration resistance (qc)
    Density index Cone resistance (qc) (from CPT) MPa Effective angle of shearing resistancea, (ϕ′)
    °
    Drained Young’s modulusb, (E′) MPa
    Very loose 0,0 – 2,5 29 – 32 < 10
    Loose 2,5 – 5,0 32 – 35 10 – 20
    Medium dense 5,0 – 10,0 35 – 37 20 – 30
    Dense 10,0 – 20,0 37 – 40 30 – 60
    Very dense > 20,0 40 – 42 60 – 90

    a) Values given are valid for sands. For silty soil a reduction of 3° should be made. For gravels 2° should be added.

    b) E′ is an approximation to the stress and time dependent secant modulus. Values given for the drained modulus correspond to settlements for 10 years. They are obtained assuming that the vertical stress distribution follows the 2:1 approximation. Furthermore, some investigations indicate that these values can be 50 % lower in silty soil and 50 % higher in gravelly soil. In over-consolidated coarse soils, the modulus can be considerably higher. When calculating settlements for ground pressures greater than 2/3 of the design bearing pressure in ultimate limit state, the modulus should be set to half of the values given in this table.

    NOTE This example was published by Bergdahl et al. (1993). For additional information and documents giving examples, see X.3.1.

D.2 Example of a correlation between the cone penetration resistance and the effective angle of shearing resistance

  1. The following is an example for deriving the effective angle of shearing resistance (ϕ′) from CPT cone penetration resistance (qc) in sands. 111
  2. The deterministic correlation reads as follows:

    ϕ′ = 13,5 × lg qc + 23

    where

    ϕ′ is the effective angle of shearing resistance, in °;
    qc is the cone penetration resistance, in MPa.

    This relationship is valid for poorly-graded sands (Cu < 3) above groundwater and cone penetration resistances in the range 5 MPa ≤ qc ≤ 28 MPa.

    NOTE 1 The example was established from electrical cone penetrometer tests and laboratory triaxial tests.

    NOTE 2 This example was published by Stenzel et al. (1978) and in DIN 4094-1 (2002). For additional information and documents giving examples, see X.3.1.

D.3 Example of a method to determine the settlement for spread foundations

  1. The following is an example of a semi-empirical method for calculating settlements of spread foundations in coarse soil. The value for Young’s modulus of elasticity (E′) derived from the cone penetration resistance (qc), to be used in this method is:
  2. The settlement (s) of a foundation under load pressure (q) is expressed as:

    Image

    where

    C1 is 1 − 0,5 × [σ′v0/(q − σ′v0)];
    C2 is 1,2 + 0,2 × lg t;
    C3 is the correction factor for the shape of the spread foundation:
    • — 1,25 for square foundations; and
    • — 1,75 for strip foundations with L > 10B;
    σ′v0 is the initial effective vertical stress at the level of the foundation;
    Image Zi is the depth influenced by the foundation pressure and width, respectively, in m. Image
    Iz is a strain influence factor (see below).
  3. Figure D.1 gives for axisymmetric (circular and square) spread foundations and for plane strain (strip spread foundations) the distribution of the vertical strain influence factor (Iz).

    NOTE 1 The cone penetration resistance (qc) in this example stems from measurements carried out with an electrical cone penetrometer.

    NOTE 2 This example was published by Schmertmann (1970) and Schmertmann et al (1978). For additional information and examples, see X.3.1.

    112

    Figure D.1 — Strain influence factor diagrams

    Figure D.1 — Strain influence factor diagrams

D.4 Example of a correlation between the oedometer modulus and the cone penetration resistance

  1. Table D.2 gives example of values of α (see 4.3.4.1 (9) Equation 4.3) for various types of soil as function of the cone penetration resistance.

    NOTE This example was published by Sanglerat (1972). For additional information and examples, see X.3.1.

    113
    Table D.2 — Examples of values of α
    Image Soil qc α
    Low-plasticity clay qc ≤ 0,7 MPa
    0,7 < qc < 2 MPa
    qc ≥ 2 MPa
    3 < α 8
    2 < α < 5
    1 < α < 2,5
    Low-plasticity silt qc < 2 MPa
    qc ≥ 2 MPa
    3 < α < 6
    1 < α < 2
    Very plastic clay
    Very plastic silt
    qc < 2 MPa
    qc > 2 MPa
    2 < α < 6
    1 < α < 2
    Very organic silt qc < 1,2 MPa 2 < α < 8
    Peat and very organic clay qc < 0,7 MPa  
      50 < w ≤ 100 (%)
    100 < w ≤ 200 (%)
    w > 200 (%)
    1,5 < α < 4
    1 < α < 1,5
    0,4 < α < 1,0
    Chalks 2 < qc ≤ 3 MPa
    qc < 3 MPa
    2 < α < 4
    1,5 < α < 3
    Sands qc < 5 MPa
    qc > 10 MPa
    α = 2
    α = 1,5 Image

D.5 Examples of establishing the stress-dependent oedometer modulus from CPT results

  1. This is an example of the derivation of the vertical stress dependent oedometer settlement modulus (Eoed), frequently recommended for settlement calculation of spread foundations, defined as follows:

    Image

    where

    w1 is the stiffness coefficient;
    w2 is the stiffness exponent;

    for sands with a uniformity coefficient CU ≤ 3, w2 = 0,5;

    for clays of low plasticity (Ip ≤ 10; wL ≤ 35), w2 = 0,6;

    σ′v is the effective vertical stress at the base of the foundation or at any depth below it due to overburden of the soil;
    Δσ′v is the effective vertical stress caused by the structure at the base of the foundation or at any depth below it;
    pa is the atmospheric pressure;
    Ip is the plasticity index
    wL is the liquid limit.
    114
  2. Values for the stiffness coefficient w1 can be derived from CPT results using for example the following equations, depending on the soil type:

    Poorly-graded sands (CU ≤ 3) above groundwater;

    Image w1 = 167 lg qc + 113     (range of validity: 5 MPa ≤ qc ≤ 30 MPa) Image

    well-graded sands (CU ≥ 6) above groundwater;

    Image w1 = 463 lg qc - 13     (range of validity: 5 MPa ≤ qc ≤ 30 MPa) Image

    low plasticity clays of at least stiff consistency (0,75 ≤ Ic ≤ 1,30) and above groundwater (IC is the consistency index);

    Image w1 = 15,2qc + 50     (range of validity: 0,6 MPa ≤ qc ≤ 3,5 MPa) Image

    NOTE 1 The example was established from the results of tests carried out with an electrical cone penetrometer and from laboratory oedometer tests.

    NOTE 2 These examples were published by Stenzel et al. (1978) and Biedermann (1984) and in DIN 4094-1:2002. For additional information and examples, see X.3.1.

D.6 Example of a correlation between compressive resistance of a single pile and cone penetration resistance

  1. In Tables D.3 and D.4 examples are given of established correlations between the results of static load tests and CPT results for coarse soil with little or no fines. Unit base pb resistance and unit shaft resistance ps of cast in-situ piles are given as a function of cone penetration resistance (qc) (CPT) and normalised pile head settlement.
    Table D.3 — Unit base resistance pb of cast in-situ piles in coarse soil with little or no fines
    Normalised settlement s/Ds; s/Db Unit base resistance pb, in MPa, at average cone penetration resistance qc (CPT) in MPa
      qc = 10 qc = 15 qc = 20 qc = 25
    0,02 0,70 1,05 1,40 1,75
    0,03 0,90 1,35 1,80 2,25
    0,10 (= Sg) 2,00 3,00 3,50 4,00

    NOTE Intermediate values may be interpolated linearly.

    In the case of cast in-situ piles with pile base enlargement, the values shall be multiplied by 0,75.

    s is the normalised pile head settlement

    Ds is the diameter of the pile shaft

    Db is the diameter of the pile base

    sg is the ultimate settlement of pile head

    115
    Table D.4 — Unit shaft resistance ps of cast in-situ piles in coarse soil with little or no fines
    Average Cone penetration resistance qc (CPT)
    MPa
    Unit shaft resistance ps
    MPa
    0 0
    5 0,040
    10 0,080
    ≥ 15 0,120
    NOTE Intermediate values may be interpolated linearly

    NOTE 1 The example was established from results of tests carried out with an electrical cone penetrometer.

    NOTE 2 This example was published in DIN 1054 (2003-01). For additional information and examples, see X.3.1.

D.7 Example of a method to determine the compressive resistance of a single pile

  1. The following is an example of the determination of the maximum bearing resistance of a single pile on the basis of the qc values from an electrical CPT. In case of over consolidation, or in case of an excavation after execution of a CPT, the qc values should be reduced.
  2. The maximum compressive resistance of a pile follows from:

    Fmax = Fmax;base + Fmax;shaft

    where

    Fmax;base = Abase × pmax;base

    and

    Image

    where

    Abase is the cross sectional area of the base, in m2;
    CP is the circumference of the part of the pile shaft in the layer in which the base of the pile is placed, in m;
    Fmax is the maximum compressive resistance of the pile, in MN;
    Fmax;base is the maximum base resistance, in MN;
    Fmax;shaft is the maximum shaft resistance, in MN;
    Image pmax;shaft;z is the maximum unit shaft resistance, at depth z, in MPa Image
    pmax;base is the maximum unit base resistance, in MPa;
    ΔL is the distance from the base of the pile to the bottom of the first soil layer above the base with qc < 2 Mpa; moreover ΔL ≤ the length of the enlarged part of the pile point if applied, in m;
    z is the depth or vertical direction (positive downwards).
    Deq is the equivalent diameter of the base, in m;
    116

    Image

    where

    a is the length of the smaller side of the base area, in m;
    b is the larger side, in m, with b ≤ 1,5 × a;
  3. The maximum base resistance pmax;base can be derived from the following equations:

    Image

    and

    pmax;base ≤ 15 MPa

    where

    αp is the pile class factor given in Table D.5,
    β is the factor which takes account of the shape of the pile point as shown in Figure D.3; β is found by interpolation between the borders given in Figure D.3
    s

    is the factor which accounts for the shape of the pile base=band is established as follows:

    Image

    where

    r is L/B
    L is the larger side of the rectangular pile point;
    B is the smaller side of the rectangular pile point;
    φ′ is the effective angle of shearing resistance.
    qc;I;mean is the mean of the qc;I values over the depth running from the pile base level to a level which is at least 0,7 times and at most 4 times the equivalent pile base diameter Deq deeper (see Figure D.2);

    Image

    with

    Image 0,7Deq < dcrit < 4Deq Image

    At the critical depth the calculated value of pmax;base becomes a minimum;

    qc;II;mean is the mean of the lowest qc;II values over the depth going upwards from the critical depth to the pile base (see Figure D.2);
    Image 117
    qc;III;mean

    is the mean value of the qc;I values over a depth interval running from pile base level to a level of 8 times the pile base diameter above the pile base, or, in case b > 1,5 × a upto 8 × a above the pile base. This procedure starts with the lowest qc;II value used for the computation of qC:II;mean (see Figure D.2);

    Image

    For continuous flight auger piles, qc;III;mean cannot exceed 2 MPa, unless the results of CPTs, which were performed at a distance from the pile ≤ 1 m after pile fabrication are used for the calculation of the compressive resistance;

  4. The maximum shaft resistance pmax;shaft;z should be determined as follows:

    pmax;shaft;z = αs × qc;z;a

    where

    αs is the factor according to Tables D.5 and D.6;
    qc;z;a is the cut-off value of qc at depth z, in MPa.

    If qc;z ≥ 12 MPa over a continuous depth interval of 1 m or more, then qc;z;a ≤ 15 MPa over this interval.

    If the depth interval with qc;z;a > 12 MPa is less than 1 m thick, then qc ≤ 12 MPa over this interval.

Table D.5 — Maximum values of αp and αs for sands and gravely sands
Pile class or type αp αsa
Soil displacement type piles, diameter > 150 mm    
- driven prefabricated piles, 1,0 0,010
- cast in place piles made by driving a steel tube with closed end. The steel pipe is reclaimed during concreting. 1,0 0,012
Soil replacement type piles, diameter > 150 mm    
- flight auger piles, 0,8 0,006 b
- bored piles (with drilling mud). 0,6 0,005
  1. Values valid for fine to coarse sands. For very coarse sands a reduction factor of 0,75 is necessary; for gravel this reduction factor is 0,5.
  2. This value is used in the case of applying the results of CPTs which were carried out before pile installation. When CPTs are used that have been carried out in the vicinity of the flight auger piles, αs, may be raised to 0,01.
118
Table D.6 — Maximum αs values for clay, silt and peat
Soil type qc,MPa αs
clay > 3 < 0,030
clay <3 < 0,020
silt   < 0,025
peat   0

Figure D.2 — Explanation of qc;I, c;II and qc;III

Figure D.2 — Explanation of qc;I, c;II and qc;III

119

Figure D.3 — Pile foot shape factor (β)

Figure D.3 — Pile foot shape factor (β)

NOTE This example was published in NEN 6743-1. For additional information and examples, see X.3.1.

120

Annex E
Pressuremeter Test (PMT)

(Informative)

E.1 Example of a method to calculate the bearing resistance of spread foundations

  1. The following is an example of a method to calculate the bearing resistance of spread foundations using a semi-empirical method and the results of an MPM test.
  2. The bearing resistance is calculated from:

    R / A′ = σv0 + k(pLMp0)

    where

    R is the resistance of the foundation against normal loads;
    A′ is the effective base area as defined in EN 1997-1 ;
    σvo is the total (initial) vertical stress at the level of the foundation base;
    pLM is the representative value of the Ménard limit pressures at the base of the spread foundation;
    po is [K0 (σv0) – u] with ko conventionally equal to 0,5, σv0 is the total (initial)vertical stress at the test level and u is the pore pressure at the test level;
    k is a bearing resistance factor given in Table E.1;
    B is the width of the foundation;
    L is the length of the foundation;
    De is the equivalent depth of foundation.
    Table E.1 — Correlations for deriving the bearing resistance factor, k, for spread foundations
    Soil category PLM category PLM MPa k
    Clay and silt A
    B
    C
    <0,7
    1,2 –2,0
    >2,5
    0,8[1 + 0,25 (0,6 + 0,4 B/L) × De/B
    0,8[ 1 + 0,35 (0,6 + 0,4 B/L) × De/B]
    0,8[1 + 0,50(0,6 + 0,4 B/L) × De/B]
    Sand and gravel A
    B
    C
    <0,5
    1,0–2,0
    >2,5
    [1 + 0,35 (0,6 + 0,4 B/L) × De/B]
    [1 + 0,50 (0,6 + 0,4 B/L) × De/B
    [1 + 0,80 (0,6 + 0,4 B/L) × De/B]
    Chalk     1,3[1 + 0,27 (0,6 + 0,4 B/L) × De/B]
    Marl and weathered rock     [1 + 0,27 (0,6 + 0,4 B/L) × De/B]

    NOTE This example was published by the French Ministère de l’Equipement du Logement et des Transport (1993). For additional information and examples, see X.3.2.

121

E.2 Example of a method to calculate the settlements for spread foundations

  1. The following is an example of a method to calculate the settlement, (s), of spread foundations using a semi-empirical method developed for MPM tests.

    Image

    where

    Bo is a reference width of 0,6 m;
    B the width of the foundation;
    λd, λc are shape factors given in Table E.2;
    α is a rheological factor given in Table E.3;
    Ec is the weighted value of Em immediately below the foundation;
    Ed is the harmonic mean of Em in all layers up to 8 × B below the foundation;
    σc is the total (initial) vertical stress at the level of the foundation base;
    q the design normal pressure applied on the foundation.
    Table E.2 — The shape coefficients, λc, λd, for settlement of spread foundations
    L/B Circle Square 2 3 5 20
    λd 1 1,12 1,53 1,78 2,14 2.65
    λc 1 1,1 1,2 1,3 1,4 1,5
    Table E.3 — Correlations for deriving the coefficient α for spread foundations
    Type of ground Description EM/pLM α
    Peat     1
    Clay Over-consolidated Image > 16 Image 1
    Normally consolidated 9–16 0,67
    Remoulded 7–9 0,5
    Silt Over-consolidated > 14 0,67
    Normally consolidated 5–14 0,5
    Sand   < 12
    5–12
    0,5
    0,33
    Sand and gravel   <10
    6–10
    0,33
    0,25
    Rock Extensively fractured   0,33
    Unaltered   0,5
    Weathered   0,67

    NOTE This example was published by the French Ministére de l’Equipement du Logement et des Transport (1993). For additional information and examples, see X.3.2.

122

E.3 Example of a method to calculate the compressive resistance of a single pile

  1. The following is an example of a method to calculate the ultimate compressive resistance, Q, of piles from the MPM test, using:

    Q = A × k × [pLM -p0] + P Σ [qsi × Zi]

    where

    A is the base area of the pile which is equal to the actual area for close ended piles and part of that area for open-ended piles;
    pLm is the representative value of the limit pressure at the base of the pile corrected for any weak layers below;
    po is [Kov0 – u] with Ko conventionally equal to 0,5, and σv0 is the total (initial) vertical stress at the test level and u is the pore pressure at the test level;
    k is a compression resistance factor given in Table E.4;
    P is the pile perimeter;
    qsi is the unit shaft resistance for soil layer i given by Figure E.1 read in conjunction with Table E.5;
    zi is the thickness of soil layer i.

    NOTE This example was published by the French Ministére de l’Equipement du Logement et des Transport (1993). For additional information and examples, see X.3.2.

    Table E.4 — Values of the compression resistance factor, k, for axially loaded piles
    Soil category pLM category pLM MPa Bored piles and
    small displacement
    pils
    Full displacement piles
    Clay and silt A
    B
    C
    <0,7
    1,2–2,0
    >2,5
    1,1
    1,2
    1,3
    1,4
    1,5
    1,6
    Sand and gravel A
    B
    C
    <0,5
    1,0 - 2,0
    >2,5
    1,0
    1,1
    1,2
    4,2
    3,7
    3,2
    Chalk A
    B
    C
    <0,7
    1,0–2,5
    <3,0
    1,1
    1,4
    1,8
    1,6
    2,2
    2,6
    Marl A
    B
    1,5–4,0
    >4,5
    1,8
    1,8
    2,6
    2,6
    Weathered rock A
    B
    2,5–4,0
    >4,5
    a a
    a) Choose k for the closest soil category.
    123
    Table E.5 — The selection of design curves for unit shaft resistance
    Soil category Clay and silt Sand and gravel Chalk Marl Weathered rock
    pLM catagory A B C A B C A B C A B  
    Pile type                        
    Bored piles and caissons No support 1 1/2 2/3   1 3 4/5 3 4/5 6
    Mud support 1 1/2 1/2 1 1/2 2/3 1 3 4/5 3 4/5 6
    Temporary casing 1 1/2 1/2 1 1/2 2/3 1 2 3/4 3 4
    Permanent casing 1 1 1 1 1 2       2 3
    Hand-dug caisson   1 2 3 1 2 3 4 5 6
    Displacement piles Closed end steel tube 1 2 2 2 2 3       3 4 4
    Prefab. concrete 1 2 2 3 3 3       3 4 4
    Driven cast in-situ 1 2 2 2 2 3 1 2 3 3 4
    Coated shaft (concrete driven steela) 1 2 2 3 3 4       3 4
    Grouted piles Low pressure 1 2 2 3 3 3 2 3 4 5 5
    High pressure 1 4 5 5 5 6 5 6 6 6 7
    1. A preformed steel pile of tubular or H-section, with enlarged shoe, is driven with simultaneous pumping of concrete (or mortar) into the annular space.

    Figure E.1 — Unit shaft resistance for axially loaded piles

    Figure E.1 — Unit shaft resistance for axially loaded piles

124

Annex F
Standard penetration test (SPT)

(Informative)

F.1 Examples of correlations between blow counts and density indices

  1. Examples of correlations of blow counts and density indices are given below.
  2. The relationship between the blow count (N60), density index ID = (emaxe)/(emaxemin) and the effective total (initial) stress σ′v;0 (kPa × 10-2) in a given sand can be represented by the expression:

    Image

    The parameters a and b in normally consolidated sands are nearly constant for 0,35 < ID < 0,85 and 0,5 < σ′v0′ < 2,5, in kPa × 10-2. (see Skempton 1986, Table 8)

  3. For normally consolidated natural sand deposits, the correlation shown in Table F.1 has been established between the normalised blow count (N1)60 and ID.
    Table F.1 — Correlation between the normalised blow count (N1)60 and the density index ID
    Image  Very loose Loose Medium Dense Very dense
    (N1)60 0–3 3–8 8–25 25–42 42–58
    ID 0% – 15% 15% – 35% 35% – 65% 65% – 85% 85% – 100% Image
  4. For fine sands, the N-values should be reduced in the ratio 55:60 and for coarse sands increased in the ratio 65:60.
  5. The resistance of sand to deformation is greater the longer the period of consolidation. This “ageing” effect is reflected in higher blow counts, and appears to cause an increase in the parameter a.

    Typical results for normally consolidated fine sands are given in Table F.2.

    Table F.2 — Effect of ageing in normally consolidated fine sands
      Age years Image
    Laboratory tests 10-2 35
    Recent fills 10 40
    Natural deposits > 102 55
    125
  6. Over-consolidation increases the coefficient b by the factor:

    Image

    where

    K0 and K0NC are the in-situ stress ratios between horizontal and vertical effective stresses for the over-consolidated and normally-consolidated sand respectively.

  7. All the above mentioned correlations have been established for predominantly silica sands. Their use in more crushable and compressible sands, such as calcareous sands or even silica sands containing a non-negligible amount of fines, may lead to an underestimation of ID.

    NOTE These examples were published by Skempton (1986). For additional information and examples, see X.3.3.

F.2 Examples of deriving values for the effective angle of shearing resistance

  1. Table F.3 is an example that can be used to derive values of the effective angle of shearing resistance of silica sands, (φ′) from the density index (ID). The values of φ′ are also influenced by the angularity of the particles and the stress level (see Table F.3).
    Table F.3 — Correlation between the density index (Id) and the effective angle of shearing resistance of silica sands, (φ′), in degrees
    Density index ID Fine Medium Coarse
    % Uniform Well-graded Uniform Well-graded Uniform Well-graded
    40 34 36 36 38 38 41
    60 36 38 38 41 41 43
    80 39 41 41 43 43 44
    100 42 43 43 44 44 46

    NOTE This example was published by the US Army Corps of Engineers (1993). For additional information and examples, see X.3.3. 3.

F.3 Example of a method to calculate the settlement of spread foundations

  1. This is an example of an empirical direct method for the calculation of settlements in granular soil of spread foundations.
  2. The settlement for stresses below the over consolidation pressure is assumed to be 1/3 of that corresponding to the normally consolidated sand. The immediate settlement, si, in mm, of a square footing of width B, in m, for an over consolidated sand, if q′ ≥ σ′p, is then given by:

    Image

    126

    where

    σ′p is maximum previous overburden pressure, in kPa;
    q′ is average effective foundation pressure, in kPa;
    Icc is af/B0,7;
    af is the foundation subgrade compressibility, Δsiq′, in mm/kPa.

    If q′ ≤ σ′p then the equation becomes:

    Image

    And for normally consolidated sands:

    Image

  3. Through a regression analysis of settlement records, the value of ICC is obtained through the expression:

    Image

    where

    Image is the average SPT blow count over the depth of influence.

    The standard error of af varies from about 1,5 for Image greater than 25 to 1,8 for Image less than about 10.

  4. The N-values for this particular empirical method should not be corrected for the overburden pressure. No mention is made of the energy ratio (Er) corresponding to the N-values. The effect of the water table is supposed to be already reflected in the measured blow count, but the correction N′ = 15 + 0,5 × (N – 15) for submerged fine or silty sands should be applied for N> 15.

    In cases involving gravels or sandy gravels, the SPT blow count should be increased by a factor of about 1,25.

  5. The value of Image is given by the arithmetic mean of the measured N-values over the depth of influence, zI = B0,75, within which 75 % of the settlement takes place for cases where N increases or is constant with depth. Where N shows a consistent decrease with depth, the depth of influence is taken as 2B or the bottom of the soft layer whichever is the lesser.
  6. A correction factor fs for the length-to-width ratio (L/B) of the foundation

    Image

    should be applied. The value of fs tends to 1,56 as L/B tends to infinity. No depth (D) correction factor has to be applied for D/B < 3.

    127
  7. Foundations in sands and gravels exhibit time-dependent settlements. A correction factor, ft, should be applied to the immediate settlement given by:

    ft = (1 + R3 + Rt lg t/3)

    where

    ft is the correction factor for time t ≥ 3 years;
    R3 is the time-dependent factor for the settlement that takes place during the first 3 years after construction; and
    Rt is the time-dependent factor for the settlement that takes place each log cycle of time after 3 years.
  8. For static loads, conservative values of R3 and Rt are 0,3 and 0,2 respectively. Thus at t = 30 years, ft = 1,5. For fluctuating loads (tall chimneys, bridges, silos, turbines etc.), values of R3 and Rt are 0,7 and 0,8 respectively so that at t = 30 years, ft = 2,5.

    NOTE This example was published by Burland and Burbridge (1985). For additional information and examples, see X.3.3.

128

Annex G
Dynamic probing test (DP)

(Informative)

G.1 Examples for correlations between number of blows and density index

  1. These are examples of the density index (ID) from the dynamic probing DP test, for different values of the uniformity coefficient (CU) (range of validity 3 ≤ N10 50):

    poorly-graded sand (CU ≤ 3) above groundwater
    ID = 0,15 + 0,260 lg N10L (DPL)
    ID = 0,10 + 0,435 lg N10H (DPH)

    poorly-graded sand (CU ≤ 3) below groundwater
    ID = 0,21 + 0,230 lg N10L (DPL)
    ID = 0,23 + 0,380 lg N10H (DPH)

    well-graded sand-gravel (CU > 6) above groundwater
    ID = −0,14 + 0,550 lg N10H (DPH).

    NOTE These examples were published by Stenzel et al. (1978) and in DIN 4094-3. For additional information and examples, see X.3.4

G.2 Example of a correlation between the effective angle of shearing resistance and the density index

  1. This is an example of deriving the effective angle of shearing resistance (φ′) from the density index (ID), for bearing capacity calculations of coarse soil (see Table G.1).
    Table G.1 — Effective angle of shearing resistance (φ′) of coarse soil as function of the density index (ID) and the uniformity coefficient (Cu)
    Soil type Grading Range of ID
    %
    Effective angle of
    shearing resistance
    (φ′)
    °
    Slightly fine-grained sand, Sand, sand-gravel Poorly graded, (CU < 6) 15–35 (loose) 30
    35–65 (medium dense) 32,5
    >65 (dense) 35
    Sand, sand-gravel, gravel Well - graded, (6 ≤ CU ≤ 15) 15–35 (loose) 30
    35–65 (medium dense) 34
    >65 (dense) 38

    NOTE This example was published in DIN 1054-100. For additional information and examples, see X.3.4

129

G.3 Example of establishing the stress-dependent oedometer modulus from DP results

  1. This is an example of the derivation of the vertical stress dependent oedometer settlement modulus (Eoed), frequently recommended for settlement calculation of spread foundations, defined as follows:

    Image

    where

    w1 is the stiffness coefficient;
    w2 is the stiffness exponent;
      for sands with a uniformity coefficient Cu ≤ 3: w2 = 0,5;
      for clays of low plasticity (Ip ≤ 10; wL ≤ 35): w2 = 0,6;
    σ′v is the effective vertical stress at the base of the foundation or at any depth below it due to overburden of the soil;
    Δσ′v is the effective vertical stress caused by the structure at the base of the foundation or at any depth below it;
    pa is the atmospheric pressure;
    Ip is the plasticity index;
    wL is the liquid limit.
  2. Values for the stiffness coefficient (w1) can be derived from DP tests using for example the following equations, depending on the soil type:

    poorly-graded sands (CU ≤ 3) above groundwater

    w1 = 2141g N10L + 71 (DPL; range of validity: 4 ≤ N10L ≤ 50)

    w1 = 249 lg N10H + 161 (DPH; range of validity: 3 ≤ N10H ≤10)

    low-plasticity clays of at least stiff consistency (0,75 ≤ Ic ≤ 1,30) and above groundwater (Ic is the consistency index)

    w1 = 4N10L + 30 (DPL; range of validity: 6 ≤ N10L ≤ 19)

    w1 = 6N10H + 50 (DPH; range of validity: 3 ≤ N10H ≤ 13).

    NOTE These examples were published by Stenzel et al. (1978) and Biedermann (1984) and in DIN 4094-3:2002. For additional information and examples, see X.3.4.

G.4 Example of correlations between the cone penetration resistance and the number of blows

  1. This is an example of estimating the cone penetration resistance (qc) in sands and sand-gravel mixtures from results with the dynamic probing test DPH to derive ultimate bearing capacities of piles from corresponding correlations established from static pile load rests (see Figure G.1, 4.3.4.2 (1)P and D.6). 130

    Figure G.1 — An example of correlations between the number of blows Nioh and the cone penetration resistance (qc) for poorly-graded sands and for well-graded sand-gravel

    Figure G.1 — An example of correlations between the number of blows Nioh and the cone penetration resistance (qc) for poorly-graded sands and for well-graded sand-gravel

    NOTE This example was published by Stenzel et al (1978) and in DIN 4094-3. For additional information and examples, see X.3.4.

G.5 Example of a correlation between number of blows of different dynamic penetrometers

  1. This is an example for correlations between the number of blows N10L of the dynamic probing test DPL and the number of blows N10H of the dynamic probing test DPH for poorly-graded sands (CU < 3) above the groundwater level:
    1. Input: DPH results;
      N10L = 3N10H;
      Range of validity: 3 ≤ N10H ≤ 20.
    2. Input: DPL results;
      N10H = 0,34 N10L;
      Range of validity: 3 ≤ N10L ≤ 50.

    NOTE These examples were published by Stenzel (1978) and Biedermann (1984) and in DIN 4094-3:2002. For clays, see Butcher, A.P. McElmeel, K., Powell, J.J.M.(1995). For additional information and examples, see X.3.4.

131

Annex H
Weight sounding test (WST)

(Informative)

  1. This Annex gives an example of values of the effective angle of shearing resistance (φ′) and drained Young’s modulus of elasticity (E′), estimated from weight sounding resistance based on Swedish experience. This example correlates the mean value of weight sounding resistance in a layer to the mean values of φ′ and E′ (see Table H.1)
    Table H.1 — Values of the effective angle of shearing resistance (ϕ′) and drained Young’s modulus of elasticity (E′) for naturally deposited quartz and feldspar sands estimated from weight sounding resistance in Sweden
    Density index Weight sounding
    resistancea,
    half-turns /0,2 m
    Effective angle of
    shearing resistanceb, (φ′),
    °
    Drained Young’s modulusc, (E′)
    MPa
    Very loose 0–10 29–32 <10
    Loose 10–30 32–35 10–20
    Medium dense 20–50 35–37 20–30
    Dense 40–90 37–40 30–60
    Very dense >80 40–42 60–90
    1. Before determination of the relative density, the weight sounding resistance in silty soil should be divided by a factor of 1,3.
    2. Values given are valid for sands. For silty soil, a reduction of 3 ° should be made. For gravels, 2 ° may be added.
    3. E′ is an approximation to the stress and time-dependent secant modulus. Values given for the drained modulus correspond to settlements after 10 years. They are obtained assuming that the vertical stress distribution follows the 2:1 approximation.
      Furthermore, some investigations indicate that these values can be 50 % lower in silty soil and 50 % higher in gravelly soil. In over-consolidated coarse soil, the modulus can be considerably higher. When calculating settlements for ground pressure greater than 2/3 of the design pressure in ultimate limit state, the modulus should be set to half the values given in this table.
  2. If only results of weight sounding tests are available, the lower value in each interval for the angle of shearing resistance and Young’s modulus in Table H.1 should be selected.
  3. When evaluating weight sounding resistance diagrams for application in Table H.1, peak values caused for example by stones or pebbles should not be accounted for. Such peak values are common in weight sounding tests in gravel.

    NOTE This example was published by Bergdahl et al. (1993). For additional information and examples, see X.3.5.

132

Annex I
Field vane test (FVT)

(Informative)

I.1 Examples of procedures to determine correction factors for the undrained shear strength

  1. Examples of procedures for the determination of correction factors of field vane test results to obtain the undrained shear strength (cu) from the measured value (cfv) of the field vane test are given in I.2 to I.5. These correction factors are based mainly on the back-analysis of embankment failures and load tests in soft clays. All procedures lead to a value of the correction factor (μ) which is used in the following equation for assessing the undrained shear strength.

    cu = μ × cfv

    where

    cfv is the undrained shear strength measured in the Field vane test
    μ is the correction factor
  2. The procedure to be used should be based on local experiences in the actual type of clay. It should also be considered that the drained shear strength might be lower than the undrained shear strength.

    NOTE For additional information see X.3.6.

I.2 Example of the determination of the correction factor μ based on Atterberg limits

  1. For soft, normally-consolidated clays, the correction factor (μ) is linked to the limit of liquidity or to the plasticity index. A sample correction curve is presented in Figure I.1.
  2. A correction factor greater than 1,2 should not be used without support from supplementary investigations.
  3. In fissured clays, a correction factor as low as 0,3 can be necessary. In fissured clays, the undrained shear strength should be determined from other methods than from Field vane tests e.g. Plate load tests.

    NOTE The Danish Geotechnical Institute (1959) gives examples of correction factors in fissured clays. For additional information see X.3.6.

    133

    Figure I.1 — An example of correction factors for cfv based on the liquid limit for normally consolidated clays

    Figure I.1 — An example of correction factors for cfv based on the liquid limit for normally consolidated clays

    NOTE Figure I.1 was published by Larsson et al. (1984). For additional information see X.3.6

    Figure I.2 — Examples of correction factors for cfV based on plasticity index and effective vertical stress (0\o) for over-consolidated clays

    Figure I.2 — Examples of correction factors for cfv based on plasticity index and effective vertical stress (σ′v0) for over-consolidated clays

I.3 Example of the determination of the correction factor μ on Atterberg limits and the state of consolidation

  1. This correction is linked to the plasticity index (IP) and the effective vertical stress (σ′v0) in the ground. Sample curves are presented in Figure I.2. 134

    NOTE Figure I.2 was published by Aas (1979). For additional information see X.3.6

I.4 Example of the determination of the correction factor μ based on Atterberg limits and state of consolidation

  1. This procedure has been elaborated in order to take into account the effect of over-consolidation.
  2. An estimate is first made of whether the clay is over-consolidated or not, using the relationship shown in Figure I.3 (relationship between the quotient of measured shear strength (cfV) by the field vane test to the effective stress (σv0) and the plasticity index (IP) for clays). If the corresponding parameters fall between the curves for “young” and “aged”, the clays are considered normally-consolidated (NC), whereas clays falling above the curve “Aged” are considered over-consolidated (OC).
  3. Normally-consolidated soils are then corrected according to the curve marked NC in Figure I.4 and over-consolidated soils are corrected according to the curve marked OC.

    Figure 1.3 — Diagram for separating normally-consolidated and over-consolidated clays

    Figure 1.3 — Diagram for separating normally-consolidated and over-consolidated clays

    NOTE This example was published by Aas et al. (1986). For additional information see X.3.6

    135

    Figure I.4 — Correction factors for normally-consolidated and over-consolidated clays

    Figure I.4 — Correction factors for normally-consolidated and over-consolidated clays

    NOTE For additional information see X.3.6

I.5 Example of the determination of the correction factor μ based on Atterberg limits and the state of consolidation

  1. This procedure has also been presented in order to take into account the effect of over-consolidation.
  2. The correction factor (μ) for normally-consolidated and slightly over-consolidated clays can be determined as

    Image

    where

    wL is the liquid limit (see Figure I.1).
  3. In clays with a higher over-consolidation ratio than 1,3, the following correction factor (μ) can be applied:

    Image

    where

    Roc is the over-consolidation ratio.

    NOTE This equation stems from Larsson and Åhnberg, (2003). For additional information see X.3.6

    136
  4. If the over-consolidation ratio has not been determined, it can be estimated empirically from the relation cfV = 0,45 × wL × σ′p. The correction factor (μ) then becomes:

    Image

    Image NOTE The equation Image stems from Hansbo (1957). For additional information see X.3.6. Image

137

Annex J
Flat dilatometer test (DMT)

(Informative)

  1. This Annex gives an example of correlations between Eoed and DMT results. These correlations may be used to determine the value of the one-dimensional tangent modulus (Eoed = d σ′/dε) from results of DMT tests, through:

    Eoed = RM × EDMT

    in which RM is estimated either on the basis of local experience or using the following relationships:

    if IDMT ≤ 0,6; then RM = 0,14 + 2,36 lg KDMT

    if 0,6 < IDMT < 3,0; then RM = RM0 + (2,5 – RM0) lg KDMT, in which
    RM0 = 0,14 + 0,15 (IDMT – 0,6)

    Image if IDMT ≥ 3; then RM = 0,5 + 2 lg KDMTImage

    if KDMT > 10; then RM = 0,32 + 2,18 lg KDMT

    if values of RM < 0,85 are obtained in the above relationships, Rm is taken to be equal to 0,85.

    where

    IDMT is material index from the flat dilatometer index
    KDMT is the horizontal stress index from the flat dilatometer test

    NOTE This example was published by Marchetti (2001). For additional information and design examples, see X.3.7.

138

Annex K
Plate loading test (PLT)

(informative)

K.1 Example of deriving the value of undrained shear strength

  1. This is an example of deriving the undrained shear strength (cu), which can be obtained using the following equation:

    Image

    where

    pu is the ultimate contact pressure from the PLT results;
    γ × z is the total stress (density times depth) at test level when the test is conducted in a borehole with a diameter smaller than three times the diameter or width of the plate;
    Nc is the bearing capacity factor; for circular plates:
    Nc = 6 (typically for PLT on the subsoil surface);
    Nc = 9 (typically for PLT in boreholes of depths greater than four times the diameter or width of the plate).

    NOTE This example was published by Marsland (1972). For additional information and examples, see X.3.8.

K.2 Example of deriving the value of the plate settlement modulus

  1. This is an example of deriving the plate settlement modulus EPLT (secant modulus).
  2. For loading tests made at ground level or in an excavation where the bottom width/diameter is at least five times the plate diameter, the plate settlement modulus (EPLT) may be calculated from the general equation:

    Image

    where

    Δp is the selected range of applied contact pressure considered;
    Δs is the change in total settlement for the corresponding change in the applied contact pressure Δp including creep settlements;
    b is the diameter of the plate;
    v is Poisson’s ratio for the conditions of the test.
  3. If not determined in other ways, v is equal to 0,5 for undrained conditions in fine soil and 0,3 forcoarse soil. 139
  4. If the test is made at the base of a borehole, the value of EPLT may be calculated from the equation:

    Image

    where

    Cz is a depth correction factor; it is defined as the ratio of the depth load to settlement of the corresponding surface load.; an example for suggested values is given in Figure K.1.

    Figure K.1 — Depth correction factor Cz as a function of plate diameter b and depth z for PLT results obtained with a uniform circular load at the base of an unlined shaft

    Figure K.1 — Depth correction factor Cz as a function of plate diameter b and depth z for PLT results obtained with a uniform circular load at the base of an unlined shaft Image

    NOTE This example was published by Burland (1969). For additional information and examples, see X.3.8.

K.3 Example of deriving the value of coefficient of sub-grade reaction

  1. This is an example of deriving the coefficient of sub-grade reaction (ks) which may be calculated from the equation:

    Image

    where

    Δp is the selected range of applied contact pressure considered;
    Δs is the change in settlement for the corresponding change in applied contact pressure Δp including creep settlements.
  2. The dimensions of the loading plate should be stated, when calculating values of ks.

    NOTE This example was published by Bergdahl (1993). For additional information see X.3.8.

140

K.4 Example of a method to calculate the settlement of spread foundations in sand

  1. This is an example of deriving settlements directly. The settlements of a footing in sand may be derived empirically according to the relations given in Figure K.3, if the ground beneath the footing to a depth larger than two times the width is the same as the ground beneath the plate (see Figure K.2).

    Figure K.2 — Influenced area beneath a test plate and a footing

    Figure K.2 — Influenced area beneath a test plate and a footing

    141

    Figure K.3 — Graph for calculations of settlement based on plate loading tests

    Figure K.3 — Graph for calculations of settlement based on plate loading tests

    NOTE This example was published by Bergdahl et al (1993). For additional information and examples, see X.3.8.

142

Annex L
Detailed information on preparation of soil specimens for testing

(Informative)

L.1 Introduction

  1. Detailed procedures are in the scope of CEN/TC 341, based on the test procedures, recommended by the European Technical Committee 5 on “Laboratory Testing” (ETC 5) of the International Society of Soil Mechanics and Geotechnical Engineering. The main requirements are given in this annex.

L.1 Preparation of disturbed soil for testing

L.2.1 Drying of soil

  1. Normally soil should not be dried before testing, unless otherwise specified, but should be used in its natural state. When drying of soil is necessary, one of the following methods should be used:

L.2.2 Disaggregating

  1. The extent of disaggregating to be applied, and the treatment of any remaining cemented material, should be related to the specific requirements and conditions, and should be specified. In particular, the disaggregating and the treatment should be done at the natural water content of the soil.
  2. Aggregations of particles should be broken down in such a way as to avoid crushing of individual particles. The action should be no more severe than that applied by a rubber-headed pestle. Special care is necessary when the soil particles are friable. If a large quantity of soil is to be prepared, disaggregating should be done in batches.

L.2.3 Subdividing

  1. Disaggregated soil should be mixed thoroughly before subdividing. The subdivision process should be repeated until representative samples of the specified minimum masses are obtained for use as test specimens.

L.2.4 Mass of disturbed soil for testing

  1. The minimum masses of disturbed soil required for testing are summarised in Table L. 1. Where the minimum mass depends on the size of the largest particles present in significant quantity, this is related to the minimum mass required for sieving (denoted by “MMS") which is given in Table L.2. 143
  2. The required mass listed in Table L.1 allows for the preparation of one test specimen, with some allowance for wastage but not for the inclusion of over-size particles. When only the fine fraction of soil is required for testing, the prepared sample of the original soil should be large enough to provide the specified mass of the desired fraction.
  3. When it is necessary to remove large particles from the initial sample in order to prepare test specimens, the size range and the proportion by dry mass of the oversize material removed should be recorded.
    Table L.1 — Mass of soil required for tests on disturbed samples
    Test Initial mass required Minimum mass of prepared test specimen
    Clay and silt Sand Gravelly soil
    Water content At least twice specimen mass 30 g 100 g D =2 mm – 10 mm MMS D > 10 mm 0,3 × MMS, min 500 g
    Particle density 100 g 10g (particle size < 4 mm)
    Grain size  
    Sieving 2 × MMS MMS
    Sedimentation  
    Hydrometer 250 g 50 g 100 g  
    Pipette 100 g 12 g 30 g  
    Consistency limits 500 g 300 g (particle size < 0,4 mm)
    Density index 8 kg a
    Dispersibility 400 g a
    Compaction S NS a
    “Proctor” mould 25 kg 10 kg
    “CBR” mould 80 kg 50 kg
    CBR 6 kg a
    Permeability b   a
    Diameter  
    100 mm 4 kg
    75 mm 3 kg
    50 mm 500 g
    38 mm 250 g
    Notation:
    D Largest particle diameter in significant proportion (10 % or more by dry mass)
    MMS Minimum mass to be taken for sieving (see Table L.2)
    NS Soil particles not susceptible to crushing
    S Soil particles susceptible to crushing during compaction
    a Mass of specimen depends on soil behaviour during test
    b Permeability specimens with height equal to twice the diameter

L.2.5 Preparation of soil for compaction

  1. Soil that is to be used for compaction-related tests should not be allowed to dry. If it is necessary to reduce the water content of the soil, this should be done by air drying. 144
  2. The upper limit of allowable particle sizes depends upon the size of the mould to be used. Particles larger than the sizes stated below should be removed before preparing the soil for testing (see Table L.3).

L.3 Preparation of undisturbed specimens

  1. The method of preparation of test specimens from undisturbed samples of soil depends on the type of sample and the type of specimen to be prepared.
  2. The approximate mass of soil required for typical laboratory test specimens is given in Table L.4. The stated mass is sufficient for one test specimen with some allowance for wastage due to trimming.

L.4 Preparation of re-compacted specimens

L.4.1 General requirements

  1. Disturbed soil may be re-compacted to form test specimens in accordance with either of the following criteria:
    Table L.2 — Minimum mass for sieving
    Largest particle
    diameter (D) mm
    Minimum mass
    for sieving (MMS) kg
    75 120
    63 70
    45 25
    37,5 15
    31,5 10
    22,4 4
    20 2
    16 1,5
    Largest particle
    diameter (D) mm
    Minimum mass
    for sieving (MMS)
    g
    11,2 600
    10 500
    8 400
    5,6 250
    4 200
    2,8 150
    ≤2 100
    145
    Table L.3 — Allowable size of particles for compaction tests
    Type of test Maximum size of particle
    Compaction — in one-litre mould
    — in CBR mould
    20 mm
    37,5 mm
    CBR determination 20 mm
    Table L.4 — Mass of soil required for tests on undisturbed samples
    Type of test Specimen dimensions Minimum mass required
    g
    Diameter mm Height mm
    Oedometer
    50 20 90
    75 20 200
    100 20 350
    Compressionb
    • – Unconfined
    • – Unconsolidated-undrained
    • – Triazial compression test
    35 70 150
    38 76 200
    50 100 450
    70 140 1 200
    100 200 3 500
    150 300 12 000
    Shear box
    Planner size
    60 × 60 20 150
    100 × 100 20 450
    300 × 300 150 30 000
    Density
    Largest particle sizea
    Largest particle size
    D = 5,6 mm 125
    D = 8 mm 300
    D = 10 mm 500
    D > 10 mm 1,4 (MMS)c
    1. D is the largest particle diameter in significant proportion (10 % or more by mass).
    2. Specimen dimensions and minimum required volume apply to all three test
    3. MMS is the minimum mass to be taken for sieving, as specified in Table L.2.
  2. Clay soil that is to be re-compacted to form test specimens should not be allowed to dry. If it is necessary to reduce the water content of the soil, this should be done by air drying. If it is necessary to add water in order to increase the water content, the water should be well mixed in and the soil should be allowed to stand in a sealed container for at least 24 hours before use.
  3. The soil should be broken down before re-compaction
  4. The upper limit of allowable particle sizes depends upon the size of the test specimen to be formed. Particles larger than the sizes given in Table L.5 should be removed before preparing the soil for re-compaction 146
  5. The particle size distribution of a re-compacted specimen should be checked before and after compaction.
    Table L.5 — Allowable particle size as a function of size of test specimen
    Type of test specimen Maximum size of particle
    Oedometer consolidation H/5a
    Direct shear (shear box) H/l0
    Compressive strength
    (cylindrical specimen with H/d of about 2)
    d/5b
    Permeability d/12
    1. H = height of specimen,
    2. d = diameter of specimen

L.4.2 Re-compacted sample larger than test specimen

  1. When preparing specimens for oedometer consolidation, direct shear or compressive strength tests, the soil should normally be compacted in the specified manner into a suitable mould that is of a larger size than the desired test specimen. The compacted sample should then be extruded from the mould and the test specimen should be prepared using the procedures described for undisturbed samples.

    NOTE The method is not suitable for granular soil.

  2. Specimens for permeability tests may be compacted directly into the mould or container in which the test is performed.
  3. For compaction using a specified effort, the compactive effort applied should normally correspond to that used in one of the two types of compaction tests specified for the compaction test (see 5.10 and Annex R). Compaction should be applied in layers, and the top of each layer should be lightly scarified before adding the next one.
  4. To obtain a specified density, the soil may either be compacted dynamically or compressed under a static load. Weighings and volume measurements should be made after placing each layer to ensure that the desired density will be achieved. Preliminary trials may be desirable to establish the appropriate method.
  5. If clay is present in the soil, the compacted sample should be sealed and stored for a curing period of at least 24 h before extrusion to form test specimens.

L.4.3 Re-compaction of test specimen

  1. For the preparation of small test specimens for direct shear, oedometer or compressive strength, the soil should be tamped, kneaded or compacted into the appropriate mould, ring or tube. A suitable hand rammer, the Harvard compaction apparatus, or a kneading action may be used. Care should be taken to avoid the formation of cavities within the specimen. The exact procedure required to obtain the desired density or compactive effort should first be determined by trial. Details should be recorded so that the procedure can be repeated to provide a number of specimens of consistent properties. 147
  2. Compaction of cylindrical test specimens of 100 mm diameter or more may be carried out using a compaction rammer. The number of layers and number of blows per layer should be specified.
  3. If clay is present in the soil, the compacted specimen should be sealed and stored for a curing period of at least 24 h before use, to allow for dissipation of excess pore water pressures.

L.4.4 Re-saturation

  1. A re-compacted specimen will invariably be initially unsaturated. Re-saturation will normally be required before testing, and this should be carried out by using one of the recognised saturation methods given in the test procedures for shear strength or compressibility tests. Full saturation should be confirmed by checking the B value, if applicable.

L.4.5 Remoulded test specimen

  1. Remoulding can be achieved by sealing the soil in a plastic bag where it is squeezed and kneaded with the fingers for several minutes. A remoulded test specimen is formed by working the soil into the appropriate mould, e.g. by using a tamping rod. This operation should be carried out as quickly as possible to avoid change of water content, and without entrapping air. The specimen should then be extruded and trimmed.

L.5 Preparation of reconstituted specimens

L.5.1 Preparation of slurry

  1. The soil should be thoroughly mixed with water to form an homogeneous slurry with a water content above the liquid limit. Preparing the slurry should preferably start from the natural water content without drying of the soil. Drying of the soil and grinding it to a powder may change its properties. If necessary, coarser particles can be removed by wet sieving using an appropriate sieve. The mixing water may be either distilled or de-ionized, or of the appropriate chemistry. The slurry should be fluid enough to be poured; a water content about twice the liquid limit is usually satisfactory.

L.5.2 Consolidation

  1. The cell in which the sample is consolidated should be large enough to provide a test specimen, or a sample for trimming, to the required size after consolidation. Provision should be made for drainage of the sample, without allowing soil particles to escape.
  2. After pouring the slurry into the mould, initial consolidation should be applied under the weight of the top plate only, until the specimen ends are stiffened enough to prevent loss of material under further loading. The vertical stress applied for consolidation should be sufficient to enable the sample to be handled when consolidated, and should be maintained for long enough to ensure that consolidation is substantially complete.
148

L.5.3 Specimen preparation

  1. The consolidated sample should be extruded from the cell and trimmed as necessary for the preparation of a test specimen or specimens.
  2. If one-dimensional consolidation tests are to be performed on the reconstituted soil, they may be carried out in the cell in which it has been consolidated from slurry.
149

Annex M
Detailed information on tests for classification, identification and description of soil

(Informative)

M.1 Checklists for classification testing

  1. The number of specimens to be tested depends on the variability of the soil and the amount of experience with the soil and to a lesser extent than other soil tests on the geotechnical problem. Table M.1 gives guidance on the number of classification tests.

    Table M.2 presents a checklist for each of soil classification tests included in the document.

Table M.1 — Classification tests. Suggested minimum number of samples to be tested in one soil stratum
Classification test Comparabe experience
No Yes
Particle size distribution 4–6 2–4
Water content All samples of Quality Class 1 to 3
Strength index test All samples of Quality Class 1
Consistency limits (Atterberg limits) 3–5 1–3
Loss on ignition (for organic and clay soil) 3–5 1–3
Bulk density Every element test
Density index As appropriate
Particle density 2 1
Carbonate content As appropriate
Sulfate content As appropriate
pH As appropriate
Chloride content As appropriate
Soil dispersibility As appropriate
Frost susceptibility As appropriate
Table M.2 — Checklist for soil classification test
Classification test Checklist
Water content Check storage method of samples
Coordinate testing programme with other classification tests
Standard oven-drying method not appropriate for gypsum, organic
soil; precautions may be needed
Report presence of gypsum, organic soil
For coarse soil, correction of measured water content may be
needed
Correction needed for saline soil 150
Bulk density Test method to be selcected
Check sampling and handling methods used
For large earthwork projects, method may need to be adapted, or use field method
For sands and gravels, correction of measured density may be needed;
Particle density Sample preparation (oven-dying versus moist specimen) can influence results
Check whether materail can have enclosed pores; for such
material, special techniques might be appropriate
Report if material has enclosed pores
If results fall outside the range of typical values, consider
additional determinations; mineralogy and organic content will affect result
Particle size analysis Selection of test method depends on particle size and gradation
Carbonates and organic matter influence test results; for such materials, remove carbonates or organic matter if appropriate, or adapt testing method
Check that correct quartering is used (particle size and sample representativeness)
Consistency limits(Atterberg limits) Selcetion of test method for liquid limit; several methods are acceptable, but fall cone method is recommended
Check storage method of samples
Check specimen preparation, especially homogenisaton and mixing
Check whether drying has been used
Drying can influence results dramatically, and should be avoided in oven
Soil that oxidise should be tested quickly
Results need not be reliable for thixotropic soil
Density index for granular soil Check storage method of samples
Select test type to be used
Results are very dependent on procedure used
Prepared specimens have high degree of non-uniformity
Soil dispersibility Need to consider specifying different compaction conditions for specimens
Avoid drying of the specimen before testing
Need to select test procedures to use
Need to run classification tests in addition
Frost susceptibility

Note Examples of methods for classification, identification and description of soil are given in the documents listed in X.4.1.

151

M.2 Water content determination

M.2.1 Evaluation of test results

  1. If the water in the soil is saline, the dissolved salts will remain in the soil after drying and may give an incorrect water content result. A more appropriate value may be the fluid content i.e. the mass of fluid (water plus salts) per unit mass of dry soil.
  2. For a coarse soil, the water content obtained in the laboratory on a sample for which the maximum grain diameter is limited by the sample size, may differ from the in place water content. In such a case, the water content should be corrected as a function of the percentage of grains that are larger than the maximum grain diameter.

NOTE Examples of methods for determination of the water content of soil are given in the documents listed in X.4.1.2.

M.3 Bulk density determination

M.3.1 Test procedures

  1. The linear measurement method is appropriate for fine soil only. For coarse soil, density can normally be determined with sufficient accuracy from in-situ tests, and more accurately from measurements on a frozen “undisturbed” sample.
  2. Table M.3 presents a guideline for the minimum number of tests required for one stratum of clay or silty soil. In the table, a specification of only one test represents a verification of the existing knowledge.
Table M.3 — Density tests. Minimum number of soil specimens to be tested for one soil stratum
Variability in measured density Comparable experience
None Medium Extensive
Range of measured density ≥ 0,02 Mg/nr3 4 3 2
Range of measured density ≤ 0,02 Mg/m3 3 2 1

NOTE Examples of methods for determination of the bulk density of soil are given in the documents listed in X.4.1.3.

M.3.2 Evaluation of test results

  1. The test results should be checked by calculating the degree of saturation, which should not exceed 100 %.
  2. For a coarse soil, the density of dry soil obtained in the laboratory on a sample for which the maximum grain diameter is limited by the sample size, may differ from the in place density of dry soil. In such a case, the density of dry soil should be corrected as a function of the percentage of grains that are larger than the maximum grain diameter.
152

M.4 Particle density determination

  1. The volume of material necessary for the determination of soil particle density is very small (minimum of 10 g with particle size less than 4 mm). The specimen is usually extracted from a specimen used for another laboratory test.
  2. In porous materials with enclosed pores, the particles only have an apparent density. The density of solid material may be found by finely grinding of the specimens and the amount of closed pores by using techniques where the volume of open pores are found using water saturation of these or gas pressure techniques in specialised laboratories. The density of solid particles should then be measured in the laboratory using a special technique.
  3. In the case of soil with organic materials, the laboratory testing should follow special procedures. Otherwise, the measured values should be used with caution.
  4. Modern methods such as the He-pycnometer may be applied. The methods should be calibrated against one of the methods more commonly used, for example the methods described in the documents listed in X.4.1.4.

NOTE Examples of methods for determination of the particle density of soil are given in the documents listed in X.4.1.4.

M.5 Particle size analysis

  1. For coarse soil (predominantly gravel and/or sand sizes), the particle size distribution of soil is determined by sieving after washing, and sedimentation is not usually necessary. For fine soil (predominantly silt and/or clay sizes), the sedimentation procedure is used, including sieving of any sand-sized particles. For mixed soil (containing all size ranges), both sieving and sedimentation procedures are used.
  2. Special care should be taken for tests on clays and organic soil. For example clay particles may have a cementing effect which can become irreversible during drying at 105 °C, organic matter becomes partly oxidised during drying at 105 °C.
  3. Modern methods that incorporate detection systems using X-rays, laser beams, density measurements, and particle counters may also be applied. They should be calibrated against the methods suggested in (2).

NOTE Examples of the methods for the particle size analysis of soil are given in the documents listed in X.4.1.5.

M.6 Density index test of granular soil

  1. The recommended minimum number of soil specimens to be tested for one soil stratum is two for the determination of the maximum density and three for the determination of the minimum density.

NOTE Examples of methods for the determination of the density index of granular soil are given in the documents listed in X.4.1.7.

153

M.7 Soil dispersibility determination

M.7.1 General

  1. Some natural clayey soils disperse rapidly in slow moving water by colloidal erosion along cracks or other flow channels. Such soil is highly susceptible to erosion and piping. The tendency for dispersive erosion in a soil depends upon the mineralogy and chemistry of the clay, and the dissolved salts in the soil pore water and the eroding water. Dispersive clays are usually high sodium content soil.

M.7.2 Test procedures for all tests

  1. Dispersibility tests are not applicable to soil with clay content of less than 10 % and with a plasticity index less than or equal to 4 %.
  2. The recommended minimum number of soil specimens to be tested for one soil stratum is two for the pinhole test, two for the double hydrometer test, two for the soluble salts in pore water test and three for the crumb test. The specification of the number of tests to be carried out should be based on engineering judgement.

NOTE Examples of methods for the testing of soil dispersibility are given in the documents listed in X.4.1.8.

M.7.3 Pinhole test

  1. It is recommended to follow the literature listed in X.4.1.8, except that:
  2. The presentation of the results should include:

    NOTE Examples of methods for the pinhole test are given in the documents listed in X.4.1.8

M.7.4 Double hydrometer test

  1. The presentation of the results should include the grain size curves obtained with and without a dispersant solution and mechanical shaking/stirring, and the percentage dispersion.
154

M.7.5 Crumb test

  1. Presentation of the results should include the soil classification as dispersive or non-dispersive and details on the reagent used.

NOTE Examples of such classifications are given in the documents listed in X.4.1.8.

M.7.6 Sodium and dissolved salts in saturation extract

  1. The report should present the exchangeable sodium percentage obtained.

    NOTE Examples of test procedures for the determination of soluble salts in the pore water, are given in the documents listed in X.4.1.8.

M.8 Frost susceptibility determination

M.8.1 Test procedures

  1. A sample in its natural state can be obtained unfrozen in soft clayey and silty soil or frozen in clay, silt and sand (without gravel). If the sample size is not directly suitable for testing, the sample can be reshaped, if done carefully.
  2. The sample that will be re-compacted can be strongly remoulded as long as the grain size distribution has not been modified by the sampling operation.
  3. The diameter of a specimen in its natural state should be at least five times the maximum grain size, and no less than 75 mm. For a reconstituted specimen, a minimum diameter of 100 mm should be used.
  4. Both natural specimens and reconstituted specimens may be saturated with back-pressure prior to the frost heave test.
  5. If a CBR test is needed, the test should be carried out on a specimen compacted at a water content close to the optimum water content, as determined from the compaction curve of a compaction test.
  6. Generally one CBR test is carried out per sample. However, several tests should be carried out to assess the influence of for example water content variations and compactive force.

    NOTE Examples of test procedures for the determination of frost susceptibility of soil and evaluations based on index tests are given in the documents listed in X.4.1.9 and X.5.

M.8.2 Evaluation of test results

  1. A soil is deemed to be frost-susceptible if it exhibits segregational heaving in the frost heave test in the laboratory.155
  2. The degree of frost action in clayey soils with low permeability is affected by the length of the winter season, i.e. the altitude and the latitude of the site considered. For these soils, the longer the winter, the more severe the frost action. This should be taken into account in northern and alpine countries.
156

Annex N
Detailed information on chemical testing of soil

(Informative)

N.1 General

N.1.1 Test procedures

  1. The above routine chemical tests are based on traditional testing methods which are within the capability of many geotechnical laboratories. Chemical tests for the presence of other substances should normally be performed by a specialist chemical laboratory.
  2. One hundred grams of dry soil is sufficient for most chemical testing. Usually a much larger sample of dried soil will be required at the outset, but a very small sample of dried soil is required for the specific testing. Thorough mixing of the initial sample, and correct sub-dividing procedures, are essential.
  3. Storage temperature before testing may influence the biological degradation of organic matter. Whenever possible, the sample material for chemical tests should be kept at a temperature of 5 °C to 10°C.
  4. Most test methods include a calibration routine using “blind” samples and reference samples. Electrochemical methods like pH have well defined calibration schemes with a number of solutions with known pH.
  5. Special requirements may call for deviations from the standard procedures, including specimen preparation. Any procedural deviations should be clearly reported, including the reasons for the deviations.

    NOTE Examples of test procedures for the five chemical tests dealt with are given in the documents listed in X.4.2. Equivalent methods also exist in other national standards and in textbooks.

N.1.2. Number of tests

  1. The number of tests specified should take into account the fact that the organic content, carbonate content, sulfate content, pH value and chloride content can vary widely even within a geological stratum. Multiple tests on closely-spaced samples may be necessary to define the local variability.

N.2 Organic content determination

N.2.1 Test procedures

  1. The loss on ignition is normally determined on a representative sample of the soil finer than 2 mm as the mass lost by ignition of a prepared specimen at the specified temperature. The organic content is calculated on the assumption that the organic mass is totally burned by the ignition, and that the mass loss is only due to the ignition of the organic matter.157
  2. The loss on ignition generally relates to the organic content of soil containing little or no clay and carbonates. For soil with higher percentage of clay and/or carbonate, factors unrelated to organic content could be responsible for the major proportion of the ignition loss.
  3. A drying temperature lower than the usual (105 ± 5) °C is necessary to avoid oxidation of some organic matter during drying. The examples listed in X.4.2.2 specify a drying temperature of (50 ± 2,5) °C, which might not remove all water. Trials may be necessary to establish a suitable drying temperature.
  4. The ignition temperature specified in the examples referred to in (1) is (440 ± 25) °C, but other standards specify temperatures up to 900 °C. Caution should be exercised when specifying an ignition temperature, taking into account the following:
  5. The drying and ignition periods should be sufficient to ensure that equilibrium has been achieved. If the period of ignition is less than 3 h, the report should document that constant mass was confirmed by repeated weighing.

    NOTE Examples of test procedures for the determination of organic content are given in the documents listed in X.4.2.2.

N.2.2 Evaluation of test results

  1. The quantity of organic carbon and organic matter can be related to loss on ignition, if the latter is corrected for other expelled constituents.
  2. The organic content can be determined by a direct measurement of the content of organic carbon, by which the errors in the loss on ignition method can be avoided.

N.3 Carbonate content determination

N.3.1 Test procedures

  1. Examples of test procedures for the determination of carbonate content are given in the documents listed in X.4.2.3. For the purpose of this standard, the rapid titration method is the preferred procedure. This method should give results that are accurate enough for soil, provided that care is taken to ensure that the dissolution process is finalised, and that sufficient duplicate tests are performed.
  2. Other examples given in the documents listed in X.4.2.3 determine the carbonate content by measuring the liberated carbon dioxide (C02) in a gasometer under controlled temperature and atmospheric pressure.
158

N.3.2 Evaluation of test results

  1. The carbonate content in percentage carbonate in the sample is expressed as the amount of CO2. This is formally correct but impractical for design. The results may be given in equivalent calcium carbonate CaCC3, i.e. the carbonate composition for most soil types. The amount of equivalent CaCo3 is obtained from the amount of C02 by the equation:

    CaCO3 = 2,273 • CO2

where

CaCO3 is the CaCO3 content as percentage of dry weight;
CO2 is the CO2 content as percentage of dry weight.

N.4 Sulfate content determination

N.4.1 Test Procedures

  1. The gravimetric method for analysis of acid or water extract or groundwater, mentioned here is suggested as the preferred one, unless it can be shown by parallel analysis that an alternative method has equal or better accuracy.
  2. The crystalline form of calcium sulfate, gypsum (CaSO4 • 2H2O) should be dried out at a temperature of 50°C. Gypsum-bearing samples begin to lose their water of crystallisation at temperatures higher than about 65°C, which can give rise to erroneously high measured water contents.
  3. The relationship between SO32− and SO42− is given by SO42− = 1,2 SO32−, with SO32− and SO42− contents expressed as a percentage.

    NOTE Examples of test procedures for the determination of sulfate content are given in the documents listed in X.4.2.4.

N.4.2 Evaluation of test results

  1. The interpretation should consider that the solubility of calcium sulfate in water is low, but in geological time, appreciable quantities can dissolve as occurs, for example, in karstic formations. Particular care is needed when results are marginal with respect to classification categories.
  2. The presence of certain other substances (notably sulfides and sesqioxides) can affect the chemical reactions, which then influence the test results. Sulfides in soil can oxidise in the long term to produce additional sulfates.
159

N.5 pH value determination (acidity and alkalinity)

N.5.1 Test procedures

  1. Several methods are available for determining values of pH. Of these, the electrometric method, which gives a direct reading of pH either in a prepared suspension of soil or in groundwater, is recommended as the definitive method.

N.5.2 Evaluation of test results

  1. Erroneous test results can be caused by:

NOTE Examples of test procedure for the determination of the pH value are given in the documents listed in X.4.2.5.

N.6 Chloride content determination

N.6.1 Test procedures

  1. Procedures for determination of chloride content include:
  2. The first two methods make use of the exchange reaction between the chlorides and silver nitrate, but different methods of analysis are used. Both methods require careful observation and weighing. The third method is based on the measurement of conductivity in dilutions of the sample with known water content.
  3. The presence of chlorides can be confirmed from a quick qualitative test: take about 5 ml of filtered groundwater, or of 1:1 soil-water extract, in a test-tube. If this is highly alkaline (pH 12-14), add a few drops of nitric acid to acidify it. Add a few drops of 1 % silver nitrate solution. Appreciable turbidity indicates that chlorides are present in a measurable quantity, which can be determined from one of the test procedures.
  4. Volhard’s method is the basis of the tests given in 7.2 (water-soluble chlorides) and 7.3 (acid-soluble chlorides) of BS 1377-3:1990 and of the method given in BS 812-118:1988 for mineral aggregates. In principle, an excess of silver nitrate solution is added to the acidified chloride solution and the unreacted portion is back-titrated with potassium thiocyanate, with ferric aluminium used as an indicator.
  5. In Mohr’s method, the test solution and a blank for comparison are each titrated with 0,02 N silver nitrate solution, potassium chromate being used as an indicator. This method is preferable for determining chlorides in groundwater.
160

NOTE Examples of test procedures are given in the documents listed in X.4.2.6.

N.6.2 Evaluation of test results

  1. The theoretical relationship between salinity expressed as sodium chloride content and chloride content need not hold due to the very mobile nature of the chloride anion.
161

Annex O
Detailed information on strength index testing of soil

(Informative)

  1. Table O.1 suggests a summary checklist on the test procedures for the strength index tests for soil included in this standard.
Table O.1 — Checklist for strength index tests on clayey soil
Strength index test Checklist
Any strength index test Tests provide approximate index of shear strength
There is a large uncertainty in the measurements
Use results cautiously for non-homogeneous and jointed/slickedsided soil
All results are affected by the applied testing rate
Test repeatability needs to be checked
Laboratory vane Test provides in addition a measure of sensitivity and remoulded shear strength
Check mode of rotation (hand-operated versus motorised)
Tests can be performed on extruded samples or in sampling tube
Fall cone Test can be performed on extruded samples or in sampling tube on intact material. This can be supplemented with a test on remoulded material to establish the sensitivity i.e. the ratio between intact and remoulded strength data
Provides in addition a measure of sensitivity on remoulded specimen
Check wear on tip of cone
Check tip cone angle

NOTE Examples of test procedures for the laboratory vane and fall cone strength index tests are given in the documents listed in X.4.3.

162

Annex P
Detailed information on strength testing of soil

(Informative)

P.1 Triaxial compression tests

P.1.1 Number of tests

  1. Table P.1 gives guidelines for the minimum number of tests required as a function of the variability of the soil and existing comparable experience with the type of soil. If only one test set is required, the test is run to provide a verification of existing knowledge. If the new test results do not agree with the existing data, more tests should be run.
  2. The number of tests may be reduced if shear stress data are available from other testing methods, for example, field tests.

    NOTE Examples of test procedures for the triaxial compression tests are given in X.4.4.

Table P.1 — Triaxial compression tests. Recommended minimum number of tests for one soil stratum
Recommended number of tests to determine the effective angle of shearing resistance a
Variability in strength envelope Coefficient of correlation r on regression curve Comparable experience
None Medium Extensive
r ≤ 0,95 4 3 2
0,95 << r ≤ 0,98 3 2 1
r≥0,98 2 1 1
Recommended number of tests to determine the undrained shear strengtha
Variability in undrained shear strength (for same consolidation stress) Comparable experience
None Medium Extensive
Ratio max/min values > 2 6 4 3
1,25 < Ratio max/min value ≤ 2 4 3 2
Ratio max/min value ≤ 1,25 3 2 1
  1. One recommended test means a set of three individual specimens tested at different cell pressures.

P.1.2 Evaluation of test results

  1. In addition to a factual evaluation, the undrained shear strength should be checked against correlations with the soil type, plasticity index, etc. The undrained shear strength evaluations should be related to the type of test that produced the results.
  2. The angle of shearing resistance should be checked against correlations with the soil type, plasticity, density index, etc. Laboratory and the in-situ stress conditions (e.g. axi-symmetrical versus plane strain conditions) should be carefully considered and in relevant cases, the angle of 163 shearing resistance should be adjusted. Relations with for example the results of cone penetration tests and existing correlations with angle of shearing resistance should also be included.

P.2 Consolidated direct shear box tests

P.2.1 Test procedures

  1. The direct shear (box or ring shear) test is run preferably for soil and stability conditions where a distinct rupture plane is expected to develop or when the strength characteristics of an interface are to be determined.
  2. Comparative studies show that the test results of direct (translational) shear box and ring shear box tests are in good agreement. The preparation of the specimen is easier in the translational shear box test. The stresses are more homogeneous in the ring shear test but the strains are not uniform. It is easier to produce large strains and thus determine the residual strength of a soil in the ring shear apparatus than in the translational shear box apparatus.
  3. Twice as much material as needed for the number of specimens tested should be taken from the stratum.

    NOTE Examples of procedures for direct shear testing are given in documents listed in X.4.4.4.

P.2.2 Number of tests

  1. Table P.2 gives a guideline for the recommended minimum number of tests required as a function of the variability of the soil and existing comparable experience with the type of soil. The recommendation applies to the case when direct shear tests are used alone to determine the shear strength of a soil stratum.
Table P.2 — Direct shear tests. Recommended minimum number of tests for one soil stratum
Recommended number of tests a
Variability in strength envelope Coefficient of correlation on regression curve Comparable experience
None Medium Extensive
Coefficient of correlation < 0,95 4 3 2
0,95 ≤ Coefficient of correlation < 0,98 3 2 2
Coefficient of correlation ≥ 0,98 2 2 1 b
  1. One recommended test means a set of three individual specimens tested at different normal stresses.
  2. A single test and classification tests to verify compatibility with comparable experience. If the test results do not agree with the existing data, additional tests should be run.
164

Annex Q
Detailed information on compressibility testing of soil

(Informative)

Q.1 Number of tests

  1. For a soil stratum which contributes significantly to the settlement of a structure, Table Q.1 gives a guideline for the minimum number of oedometer tests required as a function of the variability of the soil and the existing comparable experience with the type of soil.
  2. The number of specimens tested should be increased if the structure is very sensitive to settlements. In Table Q.1, a specification of only one test represents a verification of the existing knowledge. If the new test results do not agree with the existing data, additional tests should be run.
Table Q.1 — Incremental oedometer test. Recommended minimum number of tests for one soil stratum
Variability in oedometer modulus Eoed (in the relevant stress range) Comparable experience
None Medium Extensive
Range of values of Eoed ≥ 50 % 4 3 2
≈20 % < Range of values of Eoed < ≈50 % 3 2 2
Range of values of Eoed < ≈20 % 2 2 la
  1. One oedometer test and classification tests to verify compatibility with comparable knowledge (see Q.1 (2)).

Q.2 Evaluation of compressibility characteristics

  1. There are four widely used methods to determine the compressibility of a soil:
  2. Back-calculation from measured settlements under comparable stresses can be a reliable method to assess the compressibility characteristics (layered ground, load redistribution and time effects may be difficult to take into account). For foundations on sand and gravel, field tests such as soundings are often used: these are interpreted empirically, most often based on comparable experience. In cases where sands, coarser soil, silts and clays are expected, a combination of field and laboratory methods is desirable. Laboratory compressibility tests are most reliable for fine and organic soil, when quality class 1 samples are relatively easy to obtain.

    NOTE Examples of test procedures are given in the documents listed in X.4.5.

165

Annex R
Detailed information on compaction testing of soil

(Informative)

R.1 Test procedures applicable to both test types

  1. The minimum number of soil specimens to be tested for one soil stratum is three. The number of tests specified should be based on engineering judgement.
  2. The number of tests to be carried out should be selected considering the variation of the particle size distribution, the consistency limits and the quantity of material to be compacted. For dams, road construction etc., the number of tests to be run may be found in the relevant standards.

    NOTE Examples of test procedures for compaction testing of soil are given in the documents listed in X.4.6.

R.2 Requirements specific to compaction tests

  1. The most frequently used compaction tests are the Standard and the Modified (Proctor) Compaction Tests.
  2. Some highly permeable soils such as clean gravels, uniformly graded and coarse clean sands do not yield a well defined maximum density. Therefore optimum water content might be difficult to obtain.
  3. For stiff fine soil, suggested methods are to shred the soil so that it can pass through a 5 mm test sieve, or to chop it into pieces to pass through a 20 mm test sieve.
  4. For stiff fine soil which needs to be shredded or chopped into small lumps, the results of a compaction tests depend on the size of the resulting pieces. The densities obtained from the test will not necessarily be directly related to densities obtained in-situ.
  5. For soil not susceptible to crushing, only one sample may be used for testing. The sample can be used several times after increasing progressively the amount of water. The departure from the common procedure should be mentioned in the report.
  6. For soil containing particles that are susceptible to crushing, separate batches at different water contents should be prepared.

R.3 Requirements specific to California Bearing Ratio (CBR) test

  1. In-situ tests may be carried out, but the laboratory test is the definitive procedure.
  2. Tests may be carried out on either undisturbed or re-compacted material.
  3. The moisture content of the soil should be chosen to represent the design conditions for which the test results are required.166
  4. The CBR test should be carried out on material passing through the 20 mm test sieve. If the soil contains particles retained on the 20 mm sieve, these particles should be removed and weighed before preparing the test specimen. If the fraction retained on the 20 mm sieve is greater than 25 % by mass of the fraction passing through the 20 mm sieve, the CBR test is not applicable.
  5. Where a range of water contents is to be investigated, water should be added to or removed from the natural soil after disaggregation. The sample should not be allowed to dry.

NOTE Examples of test procedures are given in the documents listed in X.4.2.

167

Annex S
Detailed information on permeability testing of soil

(Informative)

S.1 Test procedures

  1. Twice as much material as needed for the number of specimens to be tested should be taken from the stratum.
  2. The specimens to be tested should be selected to represent the extremes in relevant soil properties, i.e. composition, density index, void ratio, etc.
  3. As a guideline, the hydraulic gradient in clays and silts should be less than 30 and less than 10 in sand.
  4. Depending on soil type and required accuracy of coefficient of permeability, the required degree of saturation in the permeability test should be considered.

    NOTE Examples of procedures for testing the permeability of soil are given in the documents listed in X.4.7.

S.2 Number of tests

  1. Table S.1 gives a guideline for the minimum number of tests required as function of the variability of the soil and existing comparable experience with the type of soil.
    Table S.1 — Permeability tests. Recommended minimum number of soil specimens to be tested for one soil stratum.
    Variability in
    measured coefficient of permeability (k)
    Comparable experience
    None Medium Extensive
    kmax/kmin > 1 00 5 4 3
    10 < kmax/kmin ≤ 100 5 3 2
    kmax/kmin ≤ 10 3 2 la
    1. A single test and classification tests to verify compatibility with existing knowledge.
  2. In Table S.1, a specification of only one test represents a verification of the existing knowledge. If the test results do not agree with the existing data, additional tests should be run.

S.3 Evaluation of test results

  1. There are four widely used methods to determine the coefficient of permeability (hydraulic conductivity): 168

    The evaluation of the coefficient of permeability can be optimised by a combination of these methods.

  2. Even in a homogeneous soil stratum, there can be a large variation in the coefficient of permeability due to small changes in stresses, void ratio, structure, particle size and bedding. The most reliable method to obtain a value of the coefficient of permeability is a field testing method.
  3. Even in a homogeneous soil stratum, the coefficient of permeability of a soil layer should be described by upper and lower limit values.
  4. For silts and clays, the derivation of the coefficient of permeability from incremental oedometer test results only gives an approximate estimate. Constant rate of strain oedometer tests provide a more direct measure of the permeability.
  5. In homogeneous sand, the coefficient of permeability may be assessed in a reasonably accurate manner from correlations with the grain size distribution.
  6. For clay, silt and organic soil where undisturbed samples of high quality can be obtained, laboratory tests may give reliable test results. The representativeness of the specimens tested should be carefully checked.
  7. For some types of soil, the degree of saturation may influence the coefficient of permeability up to as much as three orders of magnitude.
  8. The chemistry of the permeant may change the coefficient of permeability by several orders of magnitude.
169

Annex T
Preparation of specimen for testing on rock material

(Informative)

  1. The ISRM Suggested Methods for Rock Characterisation, Testing and Monitoring do not contain a specific requirement for preparation of rock specimens. However, most of the test methods contain a section on preparation of samples, with requirements on sample volume, sample quality, preparation method, specific dimensions and tolerance checks on dimensions and shape.
  2. Examples of the common practice for preparing rock core specimens and determining dimensional and shape tolerances are given in the document listed in X.4.8. In the following paragraphs, extracts of, and comments on, these documents are given.
  3. It is not always possible to obtain or prepare rock core specimens which satisfy the desirable criteria given in the ISRM suggested methods, for example for weaker, more porous, and poorly cemented rock types and rock types containing structural features.
  4. All instruments and assemblies for determining straightness, flatness and perpendicularity of end surfaces should be controlled on a registered regular time basis having tolerances satisfying at least the requirements of the specific rock tests.
  5. Most unfractured cores taken by single tube, double tube or triple tube core barrels using rotary drilling techniques can be used with or without re-coring after a trimming of the end bearing surfaces. Blocks collected directly from a rock formation may also be used, if the orientation of the block is clearly indicated on the sample that will be used for re-coring the test specimens.
  6. The required sample volume depends on the test programme. For many purposes, samples 300 mm to 1000 mm long with a diameter greater than 50 mm should be sufficient for preparing rock specimens for a group of classification, strength and deformation tests.
  7. The required quantity of cores depends highly on the natural and induced Assuring of the rock material. The initial description of the core should include an evaluation of the degree of fissuring and homogeneity. This description should be used when selecting the core sections for testing.
  8. Selection of test specimens from zones of the core without fractures may lead to non-representativeness of the test specimens for the formation. This should be taken into account in the reporting.
  9. For weaker rocks (sedimentary rocks), the sample treatment is extremely important for deformability, strength and swelling tests. The rock samples for such tests should be packed in the field as soon as obtained from the core barrel. Even a short exposure may change the water content and the inherent properties of the rock.
170

Annex U
Classification testing of rock material

(Informative)

U.1 General

  1. The classification of the rock mass based on cores calls for the highest possible core recovery to identify discontinuities and possible cavities. The disturbance of the core from the drilling process should be minimised since most rock quality designations relate to the fractures found in the cores.
  2. Most classification systems relate to cores and rotary drilling samples with a sample diameter of at least 50 mm. For most tests, a non-fractured core length of 50 mm to 200 mm long is sufficient for element testing.

    NOTE 1 Examples of tests for the classification of rock are given in the documents listed in X.4.9.

    NOTE 2 Nationally and internationally recognised classification systems exist for different purposes. Rock mass classification systems, based on semi-numerical methods, exist for engineering purposes as summarised by Bieniawski (1989) Engineering Rock Mass Classification, (see X.5).

U.2 Rock identification and description

  1. EN ISO 14689-1 applies to the description of rock for geotechnics in civil engineering. The description is carried out on cores and other samples of natural rock and on rock masses.
  2. Any published and locally approved classification system may be used, provided the report gives a traceable reference.

    NOTE Examples of additional description procedures are given in the documents listed in X.4.9.1.

U.3 Water content

U.3.1 Test procedures

  1. If specified, accuracy checks should be carried out by comparing results on specimens taken in parallel within the same formation.

    NOTE Examples of test procedures are given in the documents listed in X.4.9.2.

U.3.2 Number of tests

  1. In general, the water content should be taken at least one per metre of core.

U.4 Density and porosity

U.4.1 Test procedures

171
  1. The determination of the porosity (or void ratio) calls for a determination of the density of solid particles (or an estimate of it based on local experience with similar rock type).
  2. The existence of closed pores may influence the porosity. Determination of the total pore volume may be based on the density of solids of a powdered sample, however the determination of the amount of open and closed pores calls for specialised analysis.
  3. Methods using mercury displacement should be avoided.

NOTE Examples of test procedure are given in the documents listed in X.4.9.3.

U.4.2 Number of tests

  1. The density and porosity should be determined once at least every two metres, and at least once for each differentiated rock type unit, regardless of the rock homogeneity. The density/porosity parameters represent part of the framework for most evaluations of rock strength and deformation properties.
172

Annex V
Swelling testing of rock material

(Informative)

V.1 General

  1. Undisturbed rock specimens should preferably be tested where possible, since rock fabric has an important effect on swelling characteristics. Where the sample is too weak or too broken to allow preparation, such as joint fill material, the swelling index tests may be carried out on remoulded and re-compacted specimens. The procedures used should then be described in the report.
  2. Table V.1 gives a guideline for the minimum number of swelling tests required for different specimen dimensions. The suggestions apply for sites with a limited risk of occurrence of swelling rock types. For sites with rock types more likely to be subject to swelling, the number of tests should be increased to at least the double of the numbers given in the table. Other advanced tests may be better suited to determine the in-situ swelling performance.

    NOTE Examples of tests for swelling of rocks are given in the documents listed in X.4.10.

Table V.1 — Swelling tests on rocks. Recommended minimum number of rock specimens to be tested in one formation
Test type Minimum thickness Minimum diameter Minimum number of test specimens Notes
(1) Swelling pressure index under zero volume change 15 mm and/or 10 times max particle size 2,5 times thickness 3 Specimen should fit closely in the ring
(2) Swelling strain index for radially confined specimen with axial surcharge 15 mm and/or 10 times max particle size 4 times thickness 3 + duplicate specimens for water content Specimen should fit closely in the ring
(3) Swelling strain developed in unconfined rock specimen 15 mm and/or 10 times max particle size 15 mm and/or 10 times max particle size 3 + duplicate specimens for water content

V.2 Swelling pressure index under zero volume change

  1. The testing apparatus may often be an ordinary oedometer cell for soil consolidation. However, the apparatus should be very stiff in order to avoid influence of deformations of the cell itself.
173

NOTE An example of a test for the swelling pressure index under zero volume change is given in the document listed in X.4.10.1.

V.3 Swelling strain index for radially-confined specimen with axial surcharge

  1. The example specifies a loading device capable of applying a sustained pressure of 5 kPa to the specimen under water flooding. However, more appropriate to represent the field, may be specified. The report and any evaluation should include description of any such procedural deviations.

    NOTE An example of a test for swelling strain developed in an unconfined rock specimen is given in the document listed in X.4.10.2.

V.4 Swelling strain developed in unconfined rock specimen

NOTE An example of tests for swelling strain developed in an unconfined rock specimen is given in the document listed in X.4.10.3.

174

Annex W
Strength testing of rock material

(Informative)

W.1 Uniaxial compressive strength and deformability

W.1.1 Test procedures

  1. It is recommended to follow the methods of the ISRM or ASTM, as examples for uniaxial compressive strength testing and deformability testing. In addition the modifications prescribed in W.1 may be used.

    NOTE See X.4.11.1

  2. The test procedure described in ISRM contains two levels of testing:
  3. The first method provides the compressive strength, the second method gives in addition the axial deformation modulus (Young’s modulus) and Poisson’s ratio. The second method is preferred.
  4. The procedures suggested by the reference ISRM are extremely difficult to conform to, especially with respect to sample preparation and geometrical tolerances. The practice recommended in this informative annex is less strict. Although the procedures recommended by ISRM are desirable, a set of minimum requirements is given herein. It is considered more important to run a greater number of tests than fewer tests on higher quality specimens.
  5. The following amendments should be made to the ISRM procedure.
  6. Initial deformations may include bedding of the specimen ends to the compression machine and/or closure or micro-cracks in the test specimen. Measurement of the total vertical deformations by using only the distance between the two steel platens of the machine may lead to false deformation properties.

W.1.2 Number of tests

  1. The characteristics of rock may vary greatly as function of lithology, diagenesis or induration, stress history, weathering, and other natural processes, even within a geological stratum. Table W.1 gives a guideline for the minimum number of uniaxial compressive tests as a function of the variability of the rock and existing comparable experience.
Table W.1 - Uniaxial compression tests. Recommended minimum number of test specimens to be tested for one formation, Brazil tests and triaxial tests
Standard deviation of measured strength, (s)

% of mean

Comparable experience
None Medium Extensive
s>50 6 4 2
20 < s < 50 3 2 1
s<20 2 1 0a
  1. Only valid for very homogeneous rock types with extensive experience from nearby locations.
176

W.2 Point load test

W.2.1 Test procedures

  1. It is recommended to follow the method of ISRM as an example of a procedure for the point load test

    NOTE See X.4.11.2.

  2. The test can be run with portable equipment or using a laboratory testing equipment, and may be conducted either in the field or in the laboratory.
  3. Rock specimens in the form of either core (the diametrical and axial tests), cut blocks (the block test), or irregular lumps (the irregular lump test) may be used for testing provided the reference (for instance ISRM) specifications of shape and dimensions are followed.

W.2.2 Number of tests

  1. The mean value of the Point Load Strength Index is used to classify samples or strata. To get a representative mean value, the minimum number of single tests should be five.
  2. For rock characterization and predictions of other strength parameters, a higher number of tests than specified in W.1.2, is necessary. Generally, at least 10 separate tests per stratum should be carried out.

W.3 Direct shear test

W.3.1 Test procedures

  1. It is recommended to follow the method of ISRM as an example for the direct shear test.

    NOTE See X.4.11.3.

  2. The following amendments may be recommended to the ISRM procedure. 177
  3. The direct shear strength may also be determined by field tests. This requires a detailed assessment of the field characteristics of the discontinuities.
  4. The results are utilised in, for example, equilibrium analysis of slope stability problems or for the stability analysis of dam foundations, tunnels and underground openings.
  5. Rock specimens in the form of either cores or cut blocks may be used. The test plane should preferably have a minimum area of 2 500 mm2. In case of unfilled joints, the diameter or the edge (in the case of a square cross-section) of test specimens should preferably be related to the size of the largest grain in the rock by a ratio of at least 10:1. The ratio between joint length and shear box size is recommended not to be less than about 0,5 to avoid possible instability problems of the shear apparatus.
  6. Equipment for cutting the specimen, for example a large-diameter core drill or rock saw should be used. Percussive drills, hammers and chisels should be avoided as the samples have to be as undisturbed as possible.
  7. The direction of the test specimen in the testing machine is usually selected such that the sheared plane coincides with a plane of weakness in the rock, for example a joint, plane of bedding, schistosity or cleavage, or with the interface between soil and rock or concrete and rock.

W.3.2 Number of tests

  1. A shear strength determination should preferably comprise at least five tests on the same test horizon or from the same joint family, with each specimen tested at a different but constant normal stress in the applicable stress range.

W.4 Brazil test

W.4.1 Test procedures

  1. It is recommended to follow the method of ISRM as an example for the Brazil test.

    NOTE See X.4.11.4.

  2. Test specimens should be cut with specimen diameters (D) not less than the core size, (D ≈ 54 mm), with a thickness approximately equal to the specimen radius. The cylindrical surface should be free from obvious tool marks. Any irregularities across the thickness of the specimen should not exceed 0,025 mm. End faces should be flat within 0,25 mm and parallel to within 0,25°.
  3. For shale and other anisotropic rock, it is recommended to cut test specimens parallel to and perpendicular to the bedding. For specimens cut parallel to the direction of the bedding, the direction of the load should also be specified.

W.4.2 Number of tests

  1. Table W.1 gives a guideline for the minimum number of Brazil tests as a function of the variability of the rock and existing comparable experience. For rock characterisation and predictions of other strength parameters a higher number of tests is necessary.
178

W.5 Triaxial compression test

W.5.1 Test procedures

  1. It is recommended to follow the method of ISRM as an example for the triaxial compression test.

    NOTE See X.4.11.5.

  2. Test specimens should be cut with specimen diameter (D) not less than the core size, (D ≈ 54 mm), and the height equal to 2 to 3 times the diameter as defined in 5.4 and with the specifications in accordance with X.4.8.

W.5.2 Number of tests

  1. Table W.1 gives a guideline for the minimum number of triaxial compression tests as a function of the variability of the rock and existing comparable experience. For rock characterisation and predictions of other strength parameters a higher number of tests is necessary.
179

Annex X
Bibliography

(Informative)

X.1 Abbreviations and notations

The following notations have been used in this annex.

ASTM American Society for Testing and Materials,
BS British Standard
DGF Dansk Geoteknisk Forening (Danish Geotechnical Society),
DIN Deutsche Industrienorm (German Industrial Standard)
ETC European Technical Committee (of ISSMGE),
ISRM International Society of Rock Mechanics,
ISSMGE International Society of Soil Mechanics and Geotechnical Engineering.
NEN Nedeiiandse norm, (Dutch Standard)
NF Norme Francaise, (French Standard)
SN Schweizer Norm, (Swiss Standard)
SS Svensk Standard (Swedish Standard)

X.2 Documents related to soil and rock sampling and groundwater measurements

BS 5930:1999, Code of practice for site investigations

DIN 4021:1990, Ground exploration by excavation, boring and sampling

Hvorslev, M.J.
Subsurface exploration and sampling of soils for civil engineering purposes. US Army Engineer
Waterways Experiment Station,
Vicksburg, Miss, USA, 1949

NF XP, P 94-202:1995, Sols: Reconnaissance et essais. Prelevement des sols et des roches. Methodologie et procedures

Svensson, C.
Analysis and use of groundwater level observations.
Gothenburg: Diss. Chalmers University of Technology. Dept. Geology. Publ. A 49, 1984, (In
Swedish with abstract and summary in English)

Image X.3 Field tests8 Image

X.3.1 Cone penetration test

Bergdahl, U., Ottosson, E., Malmborg, B.S.
Plattgrundldggning (Spread Foundations) (in Swedish)
Stockholm: AB Svensk Byggtjanst, 1993
282 pages

8 The following lists contain primarily documents that give additional information and examples for determining derived values from test results and also the use of test results directly in design. The lists are divided by test type

180

Biedermann, B.
Comparative investigations with sounding methods in silt.
For schungsberichte cms Bodenmechanik and Grundbau Nr. 9 (In German).
Aachen: Technische Hochschule, 1984

DIN 1054:2003
Baugrund - Sicherheitsnachweise im Erd- und Grundbau.
(Subsoil - verification of the safety of earthworks and foundation) (in German)

DIN 4094-1:2002
Baugrund - Felduntersuchungen - Teil 1: Drucksondierungen
(Subsoil - Field investigations - Part 1: Cone penetration tests) (in German).

Lunne, T., Robertson, P.K., Powell, J.J.M.
Cone penetration testing in geotechnical practice.
Originally London: Blackie Academic & Professional, then New York: Spon Press and E&F Spon, 1997
312 pages

Melzer, K.J., Bergdahl U.
Geotechnical field investigations.
Geotechnical Engineering Handbook, Volume 1: Fundamentals.
Berlin: Ernst & Sohn, 2002
pp 51-117

NEN 6743-1:2006
Geotechniek - Berekeningsmethode voor funderingen op palen. Drukpalen.
(Geotechnics - Calculation method for bearing capacity of pile foundations. Compression piles)

Schmertmann, J.H.
Static cone to compute settlement over sand
Jnl Soil Mech. Fdns Div., ASCE, 96, SM3, May, 1970
pp 1011-1043

Schmertmann, J.H., Hartman J.P., Brown, P.R.
Improved strain influence factor diagrams
Jnl Geotech. Enging Div., ASCE, 104, GT8, Proc. Paper 7302, August, 1978
pp 1131-1135

Sanglerat, G.
The penetrometer and soil exploration
Amsterdam: Elsevier Publishing Company, 1972
464 pages

Stenzel, G., Melzer, K.J.
Soil investigations by penetration testing according to DIN 4094. (In German)
Tiefbau 20, S., 1978
pp 155-160, 240-244.

181

X.3.2 Pressuremeter test

EN ISO 22476-7 Geotechnical investigation and testing — Field testing — Part 7: Borehole jack test

Clarke B.G, Gambin M.P.
Pressuremeter testing in onshore ground investigations.
A report by ISSMGE Committee TC 16.
Atlanta: Proc. 1st Int. Conf. on Site Characterization, 1998
Vol.2, 1429-1468

Clarke, B.G.
Pressuremeters in Geotechnical design.
Glasgow: Blackie Academic and Professional, 1995
364 pages

Ministère de l’Equipement du Logement et des Transports (1993)
Règies techniques de conception et de calcul des foundations des ouvrages de Genie civil, CCTG,
Fascicule no. 62, Titre V.

X.3.3 Standard penetration test

Burland, J.B. and Burbridge, M.C.
Settlements of foundations on sand and gravel
UK: Proceedings Inst. Civil Engineers, Part 1, 78, Dec, 1985
pp 1325-1381.

Canadian Foundation Engineering Manual
Third Edition, Canadian Geotechnical Society, 1992

Technical Committee on Foundations,
BiTech Publishers Ltd, 1995.
Clayton C.R.I.

The Standard Penetration Test (SPT): methods and use.
London: Construction Industry Research Information Association (CIRIA), Report 143
143 pages

Skempton, A.W.
Standard penetration test procedures and the effects in sands of overburden pressure relative density, particle size, ageing and over-consolidation
Geotechnique 36, No. 3, 1986;
pp 425-447.

US Army Corps of Engineers
ASCE, Technical Engineering and design guides as adapted from the US Army Corps of
Engineers, No. 7:
Bearing capacity of soils (1993), ASCE Press.

182

X.3.4 Dynamic probing test

Bergdahl, U., Ottosson, E., Malmborg, B.S.
Plattgrundldggning (Spread Foundations) (in Swedish)
Stockholm: AB Svensk Byggtjänst, 1993
282 pages.

Biedermann, B.
Comparative investigations with sounding methods in silt
For schungsberichte aus Bodenmechanik und Grundbau Nr. 9 (In German)
Aachen: Technische Hochschule, 1984

Butcher, A.P. McElmeel, K., Powell, J.J.M.
Dynamic probing and its use in clay soils.
Proc Int Conf on Advances in Site Investigation Practice.
London: Inst, Civil Engineers, 1995
pp 383-395.

DIN 4094-3:2002
Baugrund - Felduntersuchungen - Teil 3: Rammsondierungen
(Subsoil - Field investigations - Part 3: Dynamic probing)
(in German).

DIN V 1054-100:1996
Baugrund - Sicherheitsnachweise im Erd- und Grundbau, Teil 100:
Berechnung nach dem Konzept mit Teilsicherheitsbeiwerten
(Soil verification of the safety of earthworks and foundation, Part 100: Analysis in accordance with the partial safety factor concept)
(in German).

Recommendations of the Committee for Waterfront Structures, Harbours and Waterways (EAU 1996).
Berlin: W. Ernst & Sohn, 2000
599 pages.

Melzer K.J., Bergdahl, U. (2002)
Geotechnical field investigations.
Geotechnical Engineering Handbook, Volume 1: Fundamentals.
Berlin: Ernst & Sohn, 2002
pages 51-117.

Stenzel, G., Melzer, K.J.
Soil investigations by penetration testing according to DIN 4094.
Tiefbau 20, S. 155 - 160, 240 - 244 (In German), 1978

X.3.5 Weight sounding test

CEN ISO/TS 22476-10, Geotechnical investigation and testing - Field testing - Part 10: Weight sounding test

183

X.3.6 Field vane test

Aas, G.
Vurdering av korttidsstabilitet i leire på basis av udrenert skjaerfasthet.
(Evaluation of short term stability in clays based on undrained shear strength) (in Norwegian); NGM -79 Helsingfors, 1979;pp. 588-596.

Aas, G., Lacasse, S., Lunne, T. Höeg, K. (1986)
Use of in-situ tests for foundation design on clay.
ASCE Geotechnical Special Publication 6.

Danish Geotechnical Institute Bulletin No. 7
Copenhagen: DGI, 1959

Hansbo, S.
A new approach to the determination of the shear strength of clay by the fall-cone test
Stockholm: Royal Swedish Geotechnical Institute, Proc. No. 14, 1957

Larsson, R., Bergdahl, U., Erikson, L.
Evaluation of shear strength in cohesive soils with special references to Swedish practice and experience
Linköping: Swedish Geotechnical Institute, Information 3E, 1984

Larsson, R., Ǡhnberg, H
The effect of slope crest excavations on the stability of slopes
Linköping: Swedish Geotechnical Institute. Report No 63, 2003

Veiledning for utførelse av vingeborr
(Recommendations for vane boring)
(in Norwegian)
Melding No. 4, Utgitt 1982, Rev. 1
Norwegian Geotechnical Institute, 1989

Recommended Standard for Field Vane Test
SGF Report 2:93E.
Swedish Geotechnical Society, 1993

X.3.7 Flat dilatometer test

CEN ISO/TS 22476-11, Geotechnical investigation and testing - Field testing - Part 11: Flat dilatometer test

Marchetti, S.
In situ test by flat dilatometer
Journal of the Geotechnical Engineering Division, Proc. ASCE, Vol. 106, N. GT3, 1980
pp 299-321.

Marchetti, S., Monaco, P., Totani, G., Calabrese, M.
The flat dilatometer test (DMT) in soil investigations
ISSMGE TCI6 Report;

184

Bali: Proc. Insitu, 2001
41 pages

X.3.8 Plate loading test

BS 1377-9:1990, Methods of test for soils for civil engineering purposes — Part 9: In situ vertical settlement and strength tests

Burland, J.B.
Reply to discussion
Proc. conf. on in situ investigations of soils and rock
London: Inst. Civil Engineers, 1969
pp 62.

Bergdahl U., Ottosson E., Malmborg B.S.
Plattgrundläggning (Spread Foundations) (in Swedish)
Stockholm: AB Svensk Byggtjänst, 1993
282 pages.

Marsland, A.
Model studies of deep in-situ loading tests in clay.
Civ. Eng. and Pub. Wks. Review, Vol 67, No 792, July 1972
pp 695,697,698.

X.4 Documents related to laboratory testing

X.4.1 Tests for classification, identification and description of soil

X.4.1.1 Site investigations

BS 5930:1999, Code of practice for site investigations

X.4.1.2 Water content determination

CEN ISO/TS 17892-1, Geotechnical investigation and testing - Laboratory testing of soil -
Part 1: Determination of water content

DIN 18 121:1998, Subsoil; testing procedures and testing equipment, water content, determination by drying in oven

NF P 94-050:1995, Soils: Investigation and testing. Determination of moisture content: Oven drying method

BS 1377-2:1990, Methods of test for soils for civil engineering purposes — Part 2: Classification tests

SN 670 340:1959, Essais; Teneur en eau / Versuche; Wassergehalt.

185

ASTM D2216:1998, Test method for laboratory determination of water (moisture) content of soil, rock, and soil-aggregate mixtures

ASTM D2974:2000, Test methods for moisture, ash, and organic matter of peat and other organic soils

ASTM D4542-95(2001), Test methods for pore water extraction and determination of the soluble salt content of soils by refractometer

SS 0271 16:1989, Geotechnical tests - Water content and degree of saturation

X.4.1.3 Bulk density determination

CEN ISO/TS 17892-2, Geotechnical investigation and testing - Laboratory testing of soil - Part 2: Determination of density of fine soils

DIN 18 125:1997, Soil, investigation and testing - Determination of density of soil Part 1: Laboratory tests

NF P 94-053:1991, Soils. Investigation and testing. Determination of density of fine soils. Cutting curb, mould and water immersion methods. Sols : Reconnaissance et Essais - Determination de la masse volumique des sols fins en laboratoire - Méthode s de la trousse coupante, du moule et de Vimmersion dans Teau.

BS 1377-2:1990, Methods of test for soil for civil engineering purposes — Part 2: Classification tests

SN 670 335:1960, Versuche; Raumgewicht; Sandersatz-Methode /Essais; Poids specifique apparent; Methode du sable

SS 0271 14:1989, Geotechnical tests - Bulk density

X.4.1.4 Particle density determination

CEN ISO/TS 17892-3, Geotechnical investigation and testing - Laboratory testing of soil - Part 3: Determination of density of soil particles

DIN 18 124:1997 Soil, investigation and testing - Determination of density of solid particles -Capillary pyknometer, wide mouth pyknometer

NF P 94-054:1991, Sols : Reconnaissance et Essais - Détermination de la masse volumique des particules solides des sols - Méthode du pycnometre á eau

BS 1377-2:1990, Methods of test for soil for civil engineering purposes — Part 2: Classification tests

SN 670 335:1960, Versuche; Raumgewicht; Sandersatz-Methode /Essais; Poids specifique apparent; Methode du sable

186

ASTM D854-02, Test Method for Specific Gravity of Soils

ASTM D4404:84 (1998), Determination of pore volume and pore volume distribution of soil and rock by mercury intrusion porosimetry

SS 0271 15:1989, Geotechnical tests - Grain density and specific gravity

X.4.1.5 Particle size analysis

CEN ISO/TS 17892-4, Geotechnical investigation and testing - Laboratory testing of soil - Part 4: Determination of particle size distribution

DIN 18 123:1996, Soil, investigation and testing - Determination of grain-size distribution

NF P 94-056:1996, Sols : Reconnaissance et Essais - Analyse gramdométrique - Méthode par tamisage à sec après lavage (in French)

XP P 94-041:1995, Sols : Reconnaissance et Essais - Identification gramdométrique – Méthode de tamisage par voie humide (in French)

BS 1377-2:1990, Methods of test for soil for civil engineering purposes — Part 2: Classification tests; Subclause 9.2 Wet sieving method

BS 1377-2:1990, Methods of test for soil for civil engineering purposes — Part 2: Classification tests; Subclause 9.5 Sedimentation by the hydrometer method

BS 1377-2:1990, Methods of test for soil for civil engineering purposes — Part 2: Classification tests; Subclause 9.4 Sedimentation by pipette method

SN 670 810c: 1986, Granulats mineraux et sols; Analyse gramdometrique par tamisage / Mineralische Baustoffe und Lockergesteine; Siebanalyse

SN 670 816:1964, Materiaux pierreux; Sédimentométrie par la méthode de l ’aréométre / Gesteinsmaterialien; Schlämmversuch nach der Araeometermethode

ASTM D2217-85 (1998), Wet preparation of s samples for particle size analysis and determination of soil constants

ASTM D422-63 (1998), Test method for particle size analysis of soil

SS 0271 23:1992, Geotechnical tests -Particle size distribution - sieving

SS 0271 24:1992, Geotechnical tests -Particle size distribution - sedimentation, hydrometer method

X.4.1.6 Consistency (Atterberg) limits determination

CEN ISO/TS 17892-12, Geotechnical investigation and testing - Laboratory testing of soil - Part 12: Atterberg limits

187

DIN 18 122:1997, Soil, investigation and testing Consistency limits Part 1: Determination of liquid-limit and plastic limit

NF P 94-051:1993, Soils. Investigation and testing. Determination of Atterberg’s limits. Liquid limit test using Casagrande apparatus. Plastic limit test on rolled thread

NF P94-052-1:1995, Sols: Reconnaissance et Essais - Détermination des limites d’Atterberg -Partie I : Limite de liquidité - Méthode du cône de pénétration

BS 1377-2:1990, Methods of test for soil for civil engineering purposes — Part 2: Classification tests; Clause 4 Determination of the liquid limit

BS 1377-2:1990, Methods of test for soil for civil engineering purposes — Part 2: Classification tests; Clause 5 Determination of the plastic limit and plasticity index

SN 670 345:1959, Essais; Limites de consistance / Versuche; Konsistenzgrenzen

SS 0271 20: 1990, Geotechnical tests - Cone liquid limit

SS 0271 21: 1990, Geotechnical tests - Plastic limit

X.4.1.7 Determination of the density index of granular soil

BS 1377-4:1990, Methods of test for soil for civil engineering purposes — Part 4: Compaction related tests; Clause 4 Determination of maximum and minimum dry densities for granular soils

NF P 94-059:2000, Sols : Reconnaissance et Essais - Détermination des masses volumiques minimale et maximale des sols non cohérents

X.4.1.8 Soil dispersibility determination

BS 1377-5:1990, Methods of test for soil for civil engineering purposes — Part 5: Compressibility, permeability and durability tests; Clause 6 Determination of dispersibility

X.4.1.9 Frost susceptibility determination

SN 670 321:1994, Essais sur les sols - Essai de gonflement au gel et essai CBR après dégel/ Versuche an Böden - Frost hebungsversuch und CBR-Versuch nach dem Auftauen

BS 1377-5:1990, Methods of test for soil for civil engineering purposes — Part 5: Compressibility, permeability and durability tests; Clause 7 Determination of frost heave

X.4.2 Chemical testing of soil and groundwater

X.4.2.1 General
188

BS 1377-3:1990, Methods of test for soil for civil engineering purposes — Part 3: Chemical and electrochemicaI tests

X.4.2.2 Organic content determination

BS 1377-3:1990, Methods of test for soil for civil engineering purposes — Part 3: Chemical and electrochemical tests; Clause 4 Determination of the mass loss on ignition or an equivalent method

ASTM D2974:1987, Test methods for moisture, ash, and organic matter of peat and other organic soils

NF P 94-055:1993, Sols : Reconnaissance et Essais - Dètermination de la teneur pondèrcde en matieres organiques d’un sol - Mèthode chimique

XP P94-047:1998, Sols : Reconnaissance et Essais - Déetermination de la teneur pondérale en matière organique - Méthode par calcination

SS 0271 05:1990, Geotechnical tests - Organic content - Ignition loss method

SS 0271 07:1990, Geotechnical tests - Organic content - Colorimetric method

X.4.2.3 Carbonate content determination

BS 1377-3:1990, Methods of test for soil for civil engineering purposes — Part 3: Chemical and electrochemical tests; Clause 6 Determination of the carbonate content

DIN 18129, Soil, investigation and testing - Determination of lime content

Head K.H., Manual of Soil Laboratory Testing. Vol.1: Soil Classification and Compaction Tests, 2nd ed; Vol 1:1992

NF P 94-048:1996, Sols : Reconnaissance et Essais - Détermination de la teneur en carbonate Méthode du calcimètre

X.4.2.4 Sulfate content determination

BS 1377-3:1990, Methods of test for soil for civil engineering purposes — Part 3: Chemical and electrochemical tests; Clause 5 Determination of the sulfate content of soil and groundwater

X.4.2.5 pH Value determination (acidity and alkalinity)

BS 1377-3:1990, Methods of test for soil for civil engineering purposes — Part 3: Chemical and electrochemical tests; Clause 9 Determination of the pH value

X.4.2.6 Chloride content determination

BS 812-118:1988, Testing aggregates. Methods for determination of sulfate content

189

BS 1377-3:1990, Methods of test for soil for civil engineering purposes — Part 3: Chemical and electrochemical tests; Subclauses 7.2, 7.3

X.4.3 Strength index testing of soil

X.4.3.1 Laboratory vane

BS 1377-7:1990, Methods of test for soils for civil engineering purposes — Part 7: Shear strength tests (total stress)

NF P 94-072:1995, Sols : Reconnaissance et Essais - Essai scissométrique en laboratoire

X.4.3.2 Fall cone

CEN ISO/TS 17892-6, Geotechnical investigation and testing - Laboratory testing of soil - Part 6: Fall cone test

SS 02 7125:1991, Geotechnical test methods. Undrained shear strength. Fall cone test Cohesive soil

X.4.4 Strength testing of soil

X.4.4.1 Unconfined compression

CEN ISO/TS 17892-7, Geotechnical investigation and testing - Laboratory testing of soil - Part 7: Unconfined compression test on fine grained soils

NF P 94-077:1997, Sols: Reconnaissance et Essais - Essai de compression uniaxiale

X.4.4.2 Unconsolidated undrained compression

CEN ISO/TS 17892-8, Geotechnical investigation and testing - Laboratory testing of soil - Part 8: Unconsolidated undrained triaxial test

NF P 94-070:1994, Sols: Reconnaissance et Essais - Essais à l’appareil triaxial de révolution -Généralités, définitions

NF P 94-074:1994, Sols: Reconnaissance et Essais - Essai à l’appareil triaxial de révolution - Appareillage - Préparation des éprouvettes - Essais (UU) non consolidé non drainé - Essai (Cu + u) consolidé non drainé avec mesure de pression interstitielle - Essai (CD) consolidé drainé.

X.4.4.3 Consolidated triaxial compression test

CEN ISO/TS 17892-9, Geotechnical investigation and testing - Laboratory testing of soil - Part 9: Consolidated triaxial compression tests on water saturated soils

BS 1377-8:1990, Methods of test for soils for civil engineering purposes — Part 8 Shear strength tests (effective stress)

190

NF P 94-070:1994, Sols: Reconnaissance et Essais - Essais à l’appareil triaxial de révolution -Généralités, définitions

NF P 94-074:1994, Sols : Reconnaissance et Essais - Essai a Vappareil triaxial de revolution - Appareillage - Preparation des eprouvettes - Essais (UU) non consolide non draine - Essai (Cu + u) consolide non draine avec mesure de pression interstitielle - Essai (CD) consolide draine.

X.4.4.4 Consolidated direct shear box tests

CEN ISO/TS 17892-10, Geotechnical investigation and testing - Laboratory testing of soil - Part 10: Direct shear tests

BS 1377-7:1990, Methods of test for soils for civil engineering purposes — Part 7: Shear strength tests (total stress)

ASTM D 3080-98, Test method for direct shear test of soils under consolidated drained conditions

SS027127, Geotechnical tests - shear strength - Direct shear test, CU- and CD- tests - Cohesive soils

NF P94-071-1:1994 Sols : Reconnaissance et Essais - Essai de cisaillement rectiligne à la boîte -Partie 1 : Cisaillement direct.

NF P94-071-2:1994, Sols : Reconnaissance et Essais - Essai de cisaillement Rectiligne à la boîte -Partie 2 : Cisaillement alterné

X.4.5 Compressibility testing of soil

CEN ISO/TS 17892-5, Geotechnical investigation and testing - Laboratory testing of soil - Part 5: Incremental loading oedometer test

BS 1377-5:1990, Methods of test for soils for civil engineering purposes — Part 5: Compressibility, permeability and durability tests

NS 8017:1991, Geotechnical testing - Laboratory methods - Determination of one-dimensional consolidation properties by oedometer testing - Method using incremental loading

ASTM D2435-96, Test method for One-Dimensional Consolidation Properties of Soils

XP P94-090-1:1997, Sols : Reconnaissance et Essais - Essai œdométrique -Partie 1 : Essai de compressibilité sur matériaux fins quasi saturés avec chargement par paliers

XP P 94-091:1995, Sols: Reconnaissance et Essais - Essai de gonflement à l’œdomètre -Détermination des déformations par chargement de plusieurs éprouvettes

SS 0271 26:1991, Geotechnical tests - Compression properties - Oedometer test, CRS-test -Cohesive soil

191

SS 0271 29: 1992, Geotechnical tests - Compression properties - Oedometer test, incremental loading - Cohesive soil

X.4.6 Compaction testing of soil

BS 1377-4:1990, Methods of test for soils for civil engineering purposes — Part 4: Compaction related tests; Clause 3 Determination of dry density/moisture content relationship

BS 1377-4:1990, Methods of test for soils for civil engineering purposes — Part 4: Compaction related tests; Clause 7 Determination of California Bearing Ratio (CBR)

NOTE ASTM D-698-78, D-1557-78 and AASHTO /99 and T180 might be used for compaction tests and ASTM D1883-94 and AASHTO T193 might be used for the California Bearing Ratio Determination. However, BS 1377:1990 has minor deviations from the specification in the US recommendations, which are used in most road laboratories.

SS027109, Geotechnical tests - Compaction properties - Laboratory compaction

NF P 94-078:1997, Sols : Reconnaissance et Essais - Indice CBR après immersion - Indice CBR immédiat - Indice Portant Immédiat - Mesure sur échantillon compacté dans le moule CBR

NF P 94-093:1999, Sols : Reconnaissance et Essais - Determination des références de compactage d’un matériau - Essai Proctor normal - Essai Proctor modifié

X.4.7 Permeability testing of soil

CEN ISO/TS 17892-11, Geotechnical investigation and testing - Laboratory testing of soil - Part 11: Permeability test

BS 1377-5:1990, Methods of test for soils for civil engineering purposes — Part 5: Compressibility, permeability and durability tests

DIN 18130-1:1998, Soil. Investigation and testing. Determination of the coefficient of water permeability. Part 1 Laboratory tests

ISO/DIS 17313, Soil quality - Determination of hydraulic conductivity of saturated porous materials using flexible wall permeameter. ISO/TC 190/SC 5.

NOTE ISO/DIS 17313 relates to environmental testing and includes some very strict normative clauses not necessary for normal geotechnical purposes.

X.4.8 Preparation of specimen for testing on rock materials

ASTM D4543-01, Preparing Rock Core Specimens and Determining Dimensional and Shape Tolerances

192

X.4.9 Classification testing of rock materials

X.4.9.1 General

BS 5930:1981, Code of practice for site investigation Section 8 Description and classification of rock for engineering purposes

ISRM Suggested Methods for Rock Characterization, Testing and Monitoring, Part 1 Site Characterization (1981).

X.4.9.2 Water content determination

ISRM Part 1, Suggested methods for determining water content, porosity, density, absorption and related properties; Section 1 Suggested method for determination of the water content of a rock sample.

X.4.9.3 Density and porosity

ISRM Part 1, Suggested methods for determining water content, porosity, density, absorption and related properties; Section 2 Suggested method for porosity/density determination using saturation and calliper techniques

ISRM Part 1, Suggested methods for determining water content, porosity, density, absorption and related properties; Section 3 Suggested method for porosity/density determination using saturation and buoyancy techniques

X.4.10 Swelling testing of rock material

X.4.10.1 Swelling pressure index under zero volume change

ISRM Suggested Methods For Determining Swelling and Slake-Durability Index Properties; Test 1 Suggested Method for Determination of the Swelling Pressure Index of Zero Volume Change

X.4.10.2 Swelling strain index for radially confined specimen with axial surcharge

ISRM Suggested Methods For Determining Swelling and Slake-Durability Index Properties; Test 2 Suggested Method for Determination of the Swelling Strain Index for a Radially Confined Specimen with Axial Surcharge

X.4.10.3 Swelling strain developed in unconfined rock specimen

ISRM Suggested Methods For Determining Swelling and Slake-Durability Index Properties; Test 3 Suggested Method for Determination of the Swelling Strain Developed in an Unconfined Rock Specimen

193

X.4.11 Strength testing of rock materials

X.4.11.1 Uniaxial compressive strength and deformability

ISRM Suggested Methods For Determining Unconfined Compressive Strength and Deformability

ASTM D 2938:1991, Standard Test Method for Unconfined Compressive Strength of Intact Rock Core Specimens

194
X.4.11.2 Point load test

ISRM Suggested Method for Determining Point Load Strength; revised version has been published in International Journal for Rock Mechanics. Min. SCI. & Geomech. Abstr. Vol 22, No. 2, pp. 51-60, 1985

X.4.11.3 Direct shear test

ISRM Suggested Method for Determining Shear Strength, Part 2: Suggested Method For Laboratory Determination of Direct Shear Strength

X.4.11.4 Brazil test

ISRM Suggested Method for Determining Tensile Strength of Rock Materials, Part 2: Suggested Method for Determining Indirect Tensile Strength by the Brazil Test

X.4.11.5 Triaxial compression test

ISRM Suggested Method for Determining the Strength of Rock Materials in Triaxial Compression

X.5 Books, articles and other publications related to laboratory testing

Bieniawski, Z.T. (1989)
Engineering Rock Mass Classification
New York: Wiley
251 p.

BRE Paper BR 279 (19--) “Sulfate and acid attack on concrete in the ground: recommended
procedures for soil analysis”.
Watford, UK: Building Research Establishment

A guide to engineering geological description
DGF Bulletin 1, Rev. 1,
DGF, May 1995

Head, K.H.
Manual of Soil Laboratory Testing. Vol.1: Soil Classification and Compaction Tests, 2nd ed.
London, Pentech Press, 1992

Head, K.H.
Manual of Soil Laboratory Testing. Vol. 2: Permeability, Shear Strength and Compressibility
Tests,
2nd ed.
London, Pentech Press, 1994

Head, K.H. (1986)
Manual of Soil Laboratory Testing. Vol. 3: Effective Stress Tests.
London, Pentech Press, 1986

195

Suggested method for determining point load strength
Min. Sci & Geomech. Abstr. Vol 22, No. 2,
International journal of Rock Mechanics
ISRM, 1985
pp. 51-60.

Sherard, K.L., Decker, R.S. and Ryker, N.L. (1972)
Piping in Earth Dams of Dispersive Clay Vol. 1, Part 1
Proc. ASCE Specialty Conf. on Performance of Earth and Earth-Supported Structures
West Lafayette, Indiana, Purdue University, June 1972
pp 589-626

Sherard, K.L., Dunnigan, L.P., Decker, R.S. and Steel, E.F.
Pinhole test for identifying dispersive soil
K. Geotechn. Eng. Div., ASCE. Vol. 102, No. GT1 (January), 1976
pp 69-85

Slunga, E. & Saarelainen, S. (1989)
Determination of frost-susceptibility of soil, A.A. Balkema
Proc. of 12th ICSMFE, Vol. 2. Session 19
Rio de Janairo, 13-18 August 1989.
pp 1465-1468

196 197