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

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.

(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 Quantity of soil

(1)P The soil specimen used for testing shall be sufficiently large to take account of:

  • the largest size of particles present in significant quantity;
  • the natural features such as structure and fabric (e.g. discontinuities).

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

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