The following information was obtained from laboratory tests on specimens from a completely saturated sample of clay:

(a) The sample had in the past been pre-compressed to at least 200 kPa.

(b) A specimen tested in direct shear under a normal stress of 600 kPa, with complete drainage allowed, showed a shearing strength of 350 kPa.

(c) A specimen which was first consolidated to 600 kPa, and then subjected to a direct shear test in which no drainage occurred, showed a shearing strength of 175 kPa. Compute ∅' and ∅T for the un-drained case. Sketch the Mohr envelopes which you would expect to obtain from a series of un-drained and drained tests on this clay. (After Taylor, 1948.)?