58 Sample storage and inspection facilities

58.1 General

A geotechnical laboratory should have appropriate facilities for handling, storing and inspecting samples. Samples should be preserved, handled and stored in accordance with BS EN ISO 22475-1.

58.2 Storage of samples

58.2.1 General

The sample storage area should be of sufficient size to cater for the number of stored samples without overcrowding and to enable the samples to be readily located when required for examination or testing. Samples labelled as containing or likely to contain hazardous substances should be stored in a separate designated area. Samples should be stored so that they are protected from damage, deterioration, loss of water, and to maintain quality as required by the test methods used on that sample. Class 1 and 2 samples should be stored at an appropriate temperature.

A record of storage temperatures for Class 1 and 2 samples should be maintained.

NOTE Samples for chemical and geoenvironmental testing have different storage temperature requirements (see BS ISO 18512).

58.2.2 Inspection facilities

A specific area should be established in the laboratory for the inspection and description of samples. This should have sufficient space for the temporary storage of the samples and an adequate area of bench space with good lighting for inspection, preferably daylight or using "daylight" artificial lighting (see Norbury, 2010 [42]). In general, the following equipment should be provided as required:

• a) an extruder for removing samples from the sample tubes or liners and a means of cutting plastic liners when extrusion is not desirable;
• b) camera, scale and other equipment (see Annex H);
• c) an adequate number of trays of suitable size to enable disturbed samples of coarse soils to be tipped out for inspection, and some means of returning them safely and quickly to their containers afterwards;
• d) spatulas, knives, hand lens, geological hammer, penknife, metre scale, protractor for logging cores, hand vane, a simple binocular microscope with appropriate magnification such as ×30;
• e) 10% (dilute) hydrochloric acid to assist identification of the presence of carbonate;
• f) an appropriate water supply to enable the fines to be washed out of samples of soils and facilitate description of the coarser particles; to clean rock cores and block samples; and to wet-up fine grained or any dry soils;
• g) a balance suitable for checking the mass of samples is sufficient for testing;
• h) means of resealing samples required for further use;
• i) washing facilities for personnel inspecting the samples; and
• j) gloves, overalls and other PPE as needed.

58.3 Sample registration and handling

58.3.1 Registration

All samples entering the laboratory should be registered and receipts issued.

58.3.2 Handling and labelling

All samples entering the laboratory should be clearly and unambiguously labelled and have a unique number, which might be a combination of the ground investigation identification, borehole number, sample number and/or depth or other system. The list of samples, in the form required by the laboratory (e.g. digital and paper form), should be supplied together with relevant data from site as required. Note should be taken of any warnings on the labels of likely hazardous substances and handling of such samples might require extra precautions as identified in the risk assessment. Samples should be treated with care to prevent damage particularly during transfer into the laboratory.

59 Selection of testing programme

The programme of laboratory testing for the project and the specification of each test should be determined by the geotechnical advisor in accordance with BS EN 1997-2 and NA to BS EN 1997-2 and other references as required for category 3 projects. Details of the tests required to determine the parameters needed for design should be specified. Each test, or series of tests, should address one or more of the purposes listed in Section 2. The principal factors that should be taken into account include:

• a) the nature of the ground and the type of soil or rock being tested;
• b) the quality of the sample;
• c) the method of analysis proposed in accordance with BS EN 1997-1 (and other methods not covered in BS EN 1997-1, such as slope stability analysis of landslides); and
• d) the requirements of the structure and the temporary works.

NOTE Further detail on common soils tests is given in Table 36 and Table 37; on shrinkage and swell tests in Table 38; specialist soil testing that might be used for category 2 or 3 projects in Table 39; on rock testing in Table 40; tests that assess the suitability as an aggregate in Table 41 and geophysical laboratory testing in Table 42. Some tests describe and classify soils and rocks; some determine parameters used in empirical analyses and the design is based on a body of past experience, while other tests determine parameters used in more rigorous theoretical analyses. Many of the tests, together with references for soils, are given in BS 1377 and BS EN ISO 17892-1 and BS EN ISO 17892-2 (as well as BS EN ISO 17892, parts 3 to 12 as they are published) and, for rocks, in International Society for Rock Mechanics (ISRM) and American Society for Testing and Materials (ASTM) methods. Further information on soil testing can also be found in Manual of soil laboratory testing, Volumes 1 to 3 [131] [132] [133].

60 Visual examination and description of laboratory samples

60.1 Description of samples

All test samples and specimens should be described prior to testing in accordance with Section 6 by an appropriately trained and experienced person. This should be separate from the description cores or samples forming part of a borehole or pit description (log). These descriptions should be included on the laboratory work sheet.

Some post-test samples, such as unconfined compressive and triaxial strength tests, should be described, drawn or photographed as required by the method. Visible surfaces of failure should be noted and their angle to the direction of externally applied direct loads recorded. Samples may be broken open to assess their uniformity and to identify any obvious reason for their behaviour. This should be done with care as the post-test sample might be required for water content determination. Other samples pre- or post-test should be photographed or sketched if required by the geotechnical advisor.

Appropriate comments should be made on the variability and disturbance of the samples.

NOTE More detailed specialist examination of samples, as required by the geotechnical advisor, might be needed, including information of the palaeontology, petrography by optical or electron microscopy to examine the fabric and texture, and mineralogical analyses.

60.2 Photographic records

COMMENTARY ON 60.2

Photographs can be used to provide a record of cores, split tube samples, typical features or a record of atypical features.

Photographic records should be kept as required. See Annex H for guidance on lighting and format.

NOTE 1 Photographs of disturbed samples can be used to show details of the particle shape and grading. The photographic record of laboratory samples might be used with those from the field showing natural or excavated faces in quarries or test pits, spoil heaps and photographs of features observed during the field reconnaissance.

NOTE 2 Photographs might be taken of samples in the "as received" state before testing and again after testing to show the mode of failure, or after splitting to show features of the fabric. Certain features might be seen more clearly after the sample has been allowed to dry or partially dry.

NOTE 3 Photomicrographs from optical or electron microscopes might be useful on occasions for instance to aid an understanding the relationship between material structure and behaviour.