中文摘要：

为描述循环荷载作用下饱和软黏土不排水应力应变特性,以Mises屈服准则构建边界约束面方程,利用硬化模量插值方法及映射中心移动方法,在偏应力空间中构建硬化模量场,建立了一个总应力形式的增量弹塑性边界面模型。该模型依据径向映射法则建立弹塑性模量插值函数,并认为加卸载过程中映射中心随加卸载路径变化而不断移动,通过弹塑性模量的插值及映射中心的移动,使得硬化模量场的演化规律表述简单,跟踪循环应力路径所需记忆的参数较少。另外,模型通过在弹塑性模量插值函数中引入反映剪应变累积速率和大小的参数控制累积剪应变随循环次数的变化规律,不仅可描述循环加载时应力应变曲线的非线性、滞回性、应变累积性等基本特性,还可预测不同初始应力水平、循环应力水平下土单元的应力应变响应。最后阐述了利用循环三轴压缩试验确定模型参数的方法,并对循环三轴拉伸试验结果进行了预测,通过预测结果与试验结果的对比,验证了所建模型的合理性。

英文摘要：

In order to simulate undrained stress-strain responses of saturated soft clays with cyclic loading, an equation elastoplastic bounding surface model is developed using the bounding surface equation which is expressed based on the Mises yield criterion, and the hardening modulus field which is described in the deviatoric stress space using methods of the hardening modulus interpolation and the mapping center movement. An incremental function of the elastoplastic modulus is established based on the radial mapping rule and the mapping center moves with the variation of loading and unloading paths for the model. Because the elastoplastic modulus interpllation function and the mapping center movement rule are used in the model, the evolution of the hardening modulus field is simple and remembered parameters are less during tracing the cyclic stress path. In addition, a parameter describing the accumulation rate and the level of shear strain is used in the elastoplastic modulus interpolation function to control the accumulation of shear strain with the number of stress cycles. The model can not only describe the nonlinear and hysteretic stress-strain responses and strain accumulation of soft clays subjected to cyclic loads but also predict the stress-strain response of soil elements with different combinations of initial and cyclic stresses. The Method determining the model parameters is also researched using the cyclic triaxial compression tests. Finally, the cyclic triaxial tensile test results are predicted using determined parameters and the rationality of the model is verified by comparing predicted results with test results.