软土循环扭剪应力应变响应的弹塑性分析

为了分析笔者提出的增量弹塑性模型对描述一般应力状态土单元循环应力应变响应的适用性,进行了软土不排水循环三轴压缩试验与无初始轴向偏应力的循环扭剪试验,得到了两种应力状态土单元的循环应力应变响应。进而依据循环三轴压缩试验结果确定模型参数,再利用模型预测软黏土循环扭剪试验土单元的应力应变响应,并与试验结果进行对比分析。结果表明,预测出的无轴向静偏应力作用的循环扭剪土单元环向剪应力应变滞回曲线与试验结果相比偏小,但是总变化趋势与试验结果较为一致;预测出的循环扭剪土单元环向累积剪应变随循环次数的变化与试验结果基本一致。研究工作表明,该增量弹塑性模型能够较好描述不同应力状态土单元的不排水循环应力应变响应,特别是循环累积应变响应。

Elastoplastic analysis of cyclic torsion stress-strain responses of soft clays

The undrained cyclic triaxial compression tests and the undrained cyclic torsional tests without static axial deviatoric stress of soft clay are conducted to analyze whether the elasto-plastic model developed by the authors can describe the stress-strain response of soil elements with general stress state. The stress-strain responses associated with two stress states are obtained from tests. Model parameters are determined from cyclic triaxial compression test results. The stress-strain responses of soil elements associated with cyclic torsional tests are predicted by the model, and the predictions and test results are compared. Comparisons show that the predicted torsional shear stress-strain loops of soil elements without static axial deviatoric stress are less than test ones, but the predicted and test variations are consistent. The predicted variations of cyclic torsional accumulative shear strains with the number of cycles are consistent with test results. Researches show that the incremental elasto-plastic model can describe undrained stress-stain responses, especially the cyclic cumulative strain response of soil elements with the general stress state.