An un-drained triaxial compression test was performed on a saturated sample of normally consolidated clay. The consolidation pressure was 100 kPa. The specimen failed when the principal stress difference was 85 kPa and the induced pore water pressure was 67 kPa. A companion un-drained test was performed on an identical sample of the same clay, but at a consolidation pressure of 250 kPa. What maximum principal stress difference would you expect at failure for this second test specimen? What are ∅ and ∅T? Predict the angle of the failure planes for the two un-drained tests.