Degradation of stiffness and strength will occur in soft clay under cyclic loading because of the generation of pore pressure. Unfortunately

previous work rarely incorporated the effect of initial deviator stress on cyclic degradation behavior. In this paper

the degradation of stiffness characteristics of normally consolidated soft clay subjected to undrained cyclic triaxial loading are investigated at different numbers of cycles

different cyclic stress levels and different initial deviator stresses. The influence of these three factors on the shear stiffness is investigated by analyzing the secant shear modulus in each unload-reload loop. It’s observed that the stiffness reduced with progressive number of cycles. On the other hand

higher cyclic stress level and initial deviator stress accelerate the degradation of stiffness. A linear relationship is obtained if secant shear modulus is plotted against numbers of cycles on a semi-log scale. This relationship has been synthesized in the form of an empirical equation. The failure stiffness ration for Xiaoshan soft clay is obtained from the equation.