Failure criteria for Xiaoshan clay under cyclic loading

Monotonic strain-controlled and cyclic loading triaxial tests have been carried out on remoulded specimens of Xiaoshan clay under undrained conditions. Considering first pore water pressures developed during cyclic loading, it is shown that the building up of pore water pressure is a time-dependent phenomenon, independent of frequency. The rate of pore water pressure accumulation decreases exponentially with elapsed time of cyclic loading and at any given time it is a function of the applied cyclic stress. A similar relationship also exists for the accumulation of the plastic strain with elapsed time. Combining the exponential relationship for pore pressure against time with the projection of the critical state line, stability criteria for Xiaoshang clay under undrained cyclic loading are developed.