Stability Criteria for Marine Clay under One‐Way Cyclic Loading

Abstract

Results are presented from a series of one‐way cyclic undrained triaxial tests on Ariake clay, a highly plastic, normally consolidated marine clay from Kyushu in southwest Japan. Considering first pore water pressures developed during cyclic loading, it is shown that the buildup of pore water pressure is a time‐dependent phenomenon, independent of frequency. The rate of pore 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 creep type of relationship also exists for the accumulation of plastic strain with time, and from this a relationship is developed between pore pressure and strain. Effective stress paths for samples taken to failure suggest that the projection of the critical state line may be taken as a failure criterion under cyclic loading. Combining the exponential relationship for pore pressure against time with this failure criterion, related stability criteria are developed for pore pressure and strains at different cyclic stress levels.