非饱和黏性土水-力耦合弹塑性组合双面模型

A combined two-surface elastoplastic model for hydro-mechanical coupling behavior of unsaturated cohesive soils

非饱和黏性土在外荷载作用下呈现出复杂的水-力耦合特性。为描述水-力耦合对非饱和土应力-应变特性的影响,基于弹塑性理论,采用提出的循环塑性硬化法则,考虑(p’-q-s)空间内的任意应力路径变化,建立能够描述非饱和黏性土水-力耦合特性的弹塑性组合双面模型。该模型通过平均骨架应力和修正吸力反映应力和吸力的耦合作用,采用2组加载面和边界面组合,分别描述加载、干湿过程中水-力耦合引起的塑性屈服,实现非饱和黏性土水-力特性的全耦合分析和求解。与非饱和黏性土的常规静力三轴剪切试验结果的比较表明,所建模型能较好地模拟非饱和黏性土水-力耦合下的应力-应变特性。

Complex hydro-mechanical coupling properties of unsaturated cohesive soils appear under external loading.In this paper,an elastoplastic two-surface model which can describe the hydro-mechanical coupling character has been formulated based on elastoplastic theory,adapting the suggested plastic hardening criterion extended to unsaturated soils,considering the arbitrary stress path variation in the(p'-q-s)space.The model reflects the coupling effect of stress and suction through mean skeleton stress and modified suction.Two groups of loading surfaces and bounding surfaces were used to describe the plastic yield induced by coupled hydro-mechanical during loading and/or dry-wetting processes respectively.The fully coupled description and solution of the hydro-mechanical characteristics of unsaturated clay are realized.Compared with the conventional triaxial shear test results of unsaturated clay,the model can better simulate the stress-strain characteristics of unsaturated clay under coupled hydro-mechanical.