考虑围压效应的冻结砂土动态本构模型研究

为描述主动围压作用下冻结砂土的动态力学特性，通过在朱-王-唐模型的非线性体上串联塑性体，建立了能够考虑围压效应的冻结砂土动态损伤本构模型；分析了损伤参数对应力-应变曲线特征、屈服点、峰值应力和峰值应变的影响规律，基于冻结砂土动力学试验数据确定了模型参数；通过将模型和试验数据进行对比，并对不同试验条件下模型的预测误差进行分析，验证了模型的适用性和准确性。结果表明，损伤参数对应力-应变曲线弹性阶段和屈服点无明显影响，而对塑性阶段和破坏阶段的影响较为显著，本构模型预测的应力-应变曲线与试验结果具有较好的一致性。模型能够预测围压引起冻结砂土塑性阶段占比大和屈服点明显的特征，且能够描述围压对冻结砂土动态强度的增强效应；不同负温和主动围压条件下，模型对峰值应力和屈服强度的预测效果优于峰值应变和屈服应变。

A study of dynamic constitutive model of frozen sandy soil considering confining pressure effect

To describe the dynamic mechanical properties of frozen sandy soil under active confining pressure, a dynamic damage constitutive model, which could consider the effect of active confining pressure on the dynamic strength and deformation characteristics of frozen sandy soil, was established by connecting a plastic body to the nonlinear Zhu-Wang-Tang model. The effects of damage parameters on the characteristics of stress-strain curves, yield point, peak stress, and peak strain were analyzed. In addition, the model parameters were determined based on the dynamic test data of frozen sandy soil. The applicability and accuracy of the established model were verified by comparing the model with the test data and analyzing its prediction errors under different test conditions. The results show that the damage parameters have no significant effect on the elastic stage and yield point of the dynamic stress-strain curves. However, it significantly affects the plastic and failure stages. The stress-strain curves predicted by the established constitutive model are in good agreement with the test results. The model is appropriate in predicting the characteristics including large portion of the plastic stage and obvious yield point caused by active confining pressure. Moreover, the model can also describe the enhancement effect of confining pressure on the dynamic compressive strength of frozen sandy soil. The predictions of the model on the peak stress and yield stress are better than those on the peak strain and yield strain under different negative temperatures and active confining pressures.