Abstract：The effects of accumulative plastic strain on degradation characteristics of Hangzhou saturated soft clay subjected to undrained cyclic triaxial loading are investigated at different cyclic stress ratios，overconsolidation ratios(OCRs)，frequencies of cyclic loading and consolidation ratios. It is observed that the degradation index is reduced with increase of accumulative plastic strain. The degradation index decreases slightly at the beginning of cyclic loading；and then the degradation index increases greatly as the strain increases. However，when the strain increases further，the degradation index changes a little. The plastic strain accumulates significantly and the relationship curves of the accumulative plastic strain and degradation index move right as the cyclic ratio increases. At a lower frequency，the curves move left with the increase of frequency. However，at a higher frequency，the effects of frequency on the relationship curves are less distinct. The curves move left as the OCR increases. The curves move upright with the increase of consolidation ratio. Based on the test results，an empirical accumulative plastic strain model is proposed by introducing a comprehensive impact parameter. The model is further introduced into modified Iwan model to describe the stress-strain relationship of soft clay. The comparison of simulation results with test data shows the proposed model is reasonable.
