A consolidated undrained (CU) test was conducted on a soil sample with cell pressure of 120 kN/m2. The deviator stress at failure was observed to be 50 kN/m2. The soil has drained cohesion C’ = 0 and drained angle of shearing resistance ϕ’ = 30°, undrained cohesion Cu = 0 & ϕu = 15°. The pore water pressure at failure is ________ kN/m2.
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