It is desired to obtain information about the in situ strength properties, c and f, for a saturated clay soil, and also the preconsolidation pressure. Direct shear tests under consolidated–undrained...

It is desired to obtain information about the in situ strength properties, c and f, for a saturated clay soil, and also the preconsolidation pressure. Direct shear tests under consolidated–undrained conditions are performed on three identical samples of the clay. For sample one, the applied normal pressure is 30 kPa and the sample fails when the shear stress is 19 kPa; for sample two, the applied normal stress is 70 kPa and the sample shears at 28 kPa; for sample three, the applied normal pressure is 120 kPa and the sample shears at 45 kPa. From these data, estimate the values of the in situ cohesion c and f_CU, and the preconsolidation stress svc.