中文摘要：

通过对杭州饱和软黏土进行应力控制的循环三轴试验,研究循环应力比、振动频率、超固结比及固结比对累积塑性应变对饱和软黏土循环软化特性的影响。试验结果表明,随着累积塑性应变的增加,软化指数减小;在循环初期,软化指数衰减缓慢;随着累积塑性应变的逐渐增加,软化指数衰减显著,但当累积塑性应变达到一定时,软化指数未见明显衰减。随着循环应力比的增加,累积塑性应变增长加快,软化指数与累积塑性应变关系曲线显著右移;当振动频率较低时,随着振动频率增加,软化指数与累积塑性应变关系曲线逐渐左移;但当振动频率较高时,不同振动频率下软化指数与累积塑性应变关系曲线近似重合。随着超固结比的增加,曲线左移,软化指数与累积塑性应变关系曲线逐渐向右、向上移动。在试验的基础上通过引入综合影响参数对试验数据进行归一化,建立饱和软黏土累积塑性应变模型。通过将该模型引入到修正的Iwan模型,并对饱和软黏土的应力–应变关系进行描述,并得到了与实测值较吻合的结果,从而也证明所提出累积塑性应变模型的合理性。

英文摘要：

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.