In a consolidated drained triaxial test on clay, the specimen failed at a deviator stress of 124 kN/m2 . If the effective stress friction angle is 31°, what was the effective confining pressure at failure? (A) 58.54 kN/m2 (B) 70.3 kN/m2 (C) 27.9 kN/m2 (D) 37.0 kN/m2
