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) :

  • geology/stratification of the ground;
  • type of structure, the possible foundation and the anticipated work during the construction;
  • type of geotechnical parameter required;
  • design method to be adopted.

(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:

  • cone penetration test;
  • pressuremeter and dilatometer tests;
  • standard penetration test;
  • dynamic probing;
  • weight sounding test;
  • field vane test;
  • flat dilatometer test;
  • plate loading test.

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:

  • ground profile to be expected;
  • desired total depth of investigation;
  • elevation of ground surface and if applicable groundwater level.

(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

4.2.2 Execution

(1)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.

NOTE Further information on a procedure, presentation and evaluation of the weight sounding test and the flat dilatometer test can be found in CRN ISO/TS 22476-10 and CEN ISO/TS 22476-11 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:

  • additional tests;
  • changing to different test methods.

(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 Tor the establishment of derived values from test results and also the use of test results directly in design.

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