A rigid retaining wall 9 ft high has backfill of soft clay soil. The properties of clay soil are the cohesion pressure (c_{u}) = 300psf and unit weight gamma = 110 pcf then find the tensile crack when varphi = 0

A specimen of saturated soil was in a cell pressure of 100 kN/m². The axial stress was then increased and drainage was prevented. The specimen failed when the axial deviator stress reached 80 kN/m² and pore water pressure 40 kN/m². Determine the consolidated angle of shearing resistance o, and drained friction angle, φ'.