A normally consolidated clay sample is subject to a triaxial test where pore water pressure measurements are made. A consolidated–undrained type of test is performed. The sample fails (shears) when...

A normally consolidated clay sample is subject to a triaxial test where pore water pressure measurements are made. A consolidated–undrained type of test is performed. The sample fails (shears) when the total all-around confining pressure is 45 kPa and the total axial pressure is 97 kPa. At failure, the recorded pore water pressure is 20 kPa. Determine the angle of internal friction fCD for the effective stress strength envelope and also the value for fcu.