Two samples of a slightly overconsolidated clay were tested in biaxial compression, and th...

Two samples of a slightly overconsolidated clay were tested in biaxial compression, and the following data at failure were obtained. The preconsolidalion stress for the clay was estimated from oedometer tests to be about 400 kPa.

(a) Determine the Skempton pore pressure parameter A at failure for both tests.

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(b) Plot the Mohr circles at failure for both total and effective stresses.

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(c) Estimate ɸ in the normally consolidated range, and c' and ɸ' for the overconsolidated range of stresses.