Abstract: This paper investigates the combined effects of dynamic stress, initial static shear stress, consolidation ratio and vibration frequency on growth of accumulative plastic strain of soft clay located in Lingang industrial district, Tianjin Binhai New Area. A series of cyclic triaxial tests is conducted with continental facies soft clay samples by GCTS triaxial torsional shear apparatus. It is observed that when shear stress increases, the ability of resisting cyclic loading enhances. The decaying rates of softening index become slow at the same time. Consolidation ratio affects similarly on growth of accumulative plastic strain. Empirical formulation between softening index and accumulative plastic strain is established considering various influencing factors above-mentioned. Based on previous results, referring to the relationship between softening index and vibration times of cyclic loading N, a new accumulative plastic strain growth model is proposed for soft clay in Tianjin Binhai New Area, including four types of influence factors. And applicability of this model is verified.

Key words: cyclic loading, accumulative plastic strain, softening index, initial static shear stress, consolidation ratio, vibration frequency