A clay sample is hydrostatically consolidated to 1.0 MPa and then sheared un-drained. The (1 - 3)

A clay sample is hydrostatically consolidated to 1.0 MPa and then sheared un-drained. The (σ1 - σ3) at failure was also equal to 1 MPa. If drained tests on identical samples gave ∅' = 22o, evaluate the pore pressure at failure in the un-drained test and compute Skempton's A parameter.