End of borehole 12.00m ©


4.11.3 Specification of laboratory tests

Example 4.3 considers the amount of laboratory testing required for the hotel site according to Eurocode 7 Part 2. The guidance given in Annexes M to S allows the number of tests to be carried out on each stratum to be determined. This number depends on how much prior knowledge of the site exists and the expected variation in ground properties.

Assuming that the borehole log given in Section 4.11.2 is typical, but we have little previous experience of the site, we have indicated the amount of testing needed to allow the design of shallow or piled foundations in the box below. In practice, not all these tests would be carried out on samples from one borehole. Instead an assessment would be made of the lateral extent of each stratum and samples from different boreholes (but from the same stratum) would be used. More testing would be required of parameters whose value varies with depth in order to identify this variation.

Notes on Example 4.3

O We assume that effective stress testing of clays will not be necessary for this project.

© It may be better to establish effective stress parameters for granular soils from in situ tests rather than from laboratory tests. Eurocode 7 allows relevant in situ tests to be used in place of laboratory tests.

© The boulder clay is only 0.4m thick in the borehole log of Section 4.11.2 and it may therefore be impractical to carry out all the testing specified owing to a lack of material to test.

© The symbol Eoed is used here to mean all associated and equivalent consolidation parameters, such as the coefficient of consolidation cv and coefficient of compressibility mv.

Example 4.3 Specification of laboratory tests


PSD Attf Det Cu c', Eoed O

Brown friable gravelly TOPSOIL (Made Ground)


Stiff brown sandy becoming gravelly CLAY

4 3 4 5 - © 4

Dense brown clayey SAND & GRAVEL

4 3w - - 3 © -

Stiff brown boulder CLAY ©

4 3 4 5 - © 4

Dense brown gravelly fine to coarse SAND

4 3w - - 3 © -

Dense dark brown fine to coarse SAND

4 3w - - 3 © -

*- indicates not applicable; tAtterberg limits (wL and wP) and water content (w); w after number indicates water content only; ^Density

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