砂土非共轴本构模型及其在地基承载力方面的应用

Three-dimensional non-coaxial constitutive model for sand and its application in bearing capacity of foundation

传统弹塑性模型隐含了塑性应变率与应力方向共轴的假设,无法模拟砂土在非比例加载条件下的非共轴特性。对传统模型隐含的共轴假设进行了剖析,将Hashiguchi等的广义非共轴塑性流动理论引入Li等建立的砂土状态相关剪胀模型中,构建了一个砂土的非共轴模型。Leighton-Buzzard砂的单剪试验模拟表明,非共轴模型能够更加合理地描试验结果。开发了相应的有限元程序,利用所建模型对不同孔隙比条件下的砂土地基承载力问题进行了模拟。探讨了非共轴参数取值对计算结果的影响,总体上预测结果展现出与单剪试验模拟相一致的规律。

Due to the coaxial assumption that the direction of plastic strain rate is the same as that of stress, the non-coaxial behavior of sand under non-proportional loading conditions can not be captured by the conventional elastic-plastic model. In this study, firstly the cause of coaxial hypothesis contained in the traditional model is analyzed. Then, a non-coaxial model for sand is constructed by introducing the generalized non-coaxial plastic flow theory developed by Hashiguchi et al into the state-dependent dilatancy model for sand established by Li et al. The simulation of simple shear tests on Leighton-Buzzard sand shows that the non-coaxial model can describe the experimental results more reasonably. The corresponding finite element program is developed, the bearing capacity of sand foundation under different void ratios is analyzed by using the proposed model. The influence of non-coaxial parameters on the calculation results is discussed, and the predicted results demonstrate similar characteristics with those of simple shear test simulation on the whole.