循环荷载作用下流变性软黏土的边界面模型

为了预测交通荷载作用下流变性软黏土的长期运行沉降,提出了一个能够描述循环加载条件下饱和软黏土流变特性的弹黏塑性本构模型。本模型以边界面弹塑性理论为基础,采用滞后变形理论。模型不仅能单独考虑土体的流变效应和循环加卸载效应,还能考虑交通荷载作用下软黏土在循环荷载和流变耦合作用下的变形特性。模型概念清晰,参数少。通过多组上海软黏土循环加载流变试验结果的模拟,初步验证了本模型的合理性和有效性。

A bounding surface model for creeping soft clays under cyclic loading

In order to simulate the mechanical behavior of creeping soft clay under cyclic loading, a time-dependent constitutive model was developed within the theoretical framework of bounding surface plasticity to incorporate the effects of cyclic path and rheological behavior. The model was based on the concept of delayed plastic strain. It was assumed that the total strain could be decomposed into an immediate elastic part, an immediate plastic part, and a delayed part, where the delayed strain could further be divided into volumetric creep strain and deviatoric creep strain. The model had a few extra parameters more than those of the traditional Cam-clay model, which could be easily determined by conventional laboratory tests. The predictive capacities of model were examined by comparing with cyclic test data of creeping saturated soft clay of Shanghai. It was shown that the agreement between the model predictions and experimental results was satisfactory in general, and the proposed model could simulate realistically the main mechanical behavior of creeping soft clay of Shanghai under cyclic loading.