中文摘要：

结构性黄土的强度和变形特性与其内部的结构破损密切相关，限于微结构测试技术的限制，结构的逐渐破损规律还未能试验测试得到，因此将离散元数值试验所得理想结构性黄土在荷载和水作用下的破损演变规律，引入到应变分担形式的二元介质模型中，获得模型的响应并用于检验所得破损演变规律的合理性。首先给出了模型的本构方程，其中胶结元采用弹性模型，摩擦元采用修正剑桥模型，破损参数的函数形式通过对结构性黄土试样在加载和增湿作用下的离散元数值试验获得，然后应用编制的单元试验数值计算程序，检验了模型在一维压缩、一维湿陷、三轴压缩和三轴湿陷试验中的力学响应。结果表明该模型能够反映一维压缩试验中的压缩变形特性，一维湿陷试验中湿陷系数随压力的变化规律，三轴剪切试验中体变随围压的变化、初始弹性模量随围压的变化和三轴湿陷试验中逐步增湿的变形规律，胶结元的参数对力学特性影响较大，总体上在三轴压缩试验应变硬化时，离散元数值试验所得破损参数的变化规律比已有破损规律合理。

英文摘要：

The strength and deformation character of structured loess are closely related to the breakage of internal microstructure and the breakage law of microstructure has not been measured by experiment due to the limitation of microstructure test technology. Hence the evolution law of the breakage parameter for ideal structured loess under loading and wetting, which is obtained by discrete element method（DEM）, is incorporated in the binary medium model with the form of strain sharing and the mechanical responses of the model are obtained to verify the reasonability of the breakage evolution law. Firstly, the constitutive equations are given, in which the model of bonding element adopts elastic model, frictional element adopts modified cam clay model and the formula form of breakage parameter are obtained from the numerical test on the ideal structured loess under loading and wetting. Secondly, the numerical program is compiled to verify the behavior of the model in one dimensional compression test, one dimensional wetting test, conventional triaxial compression test and the triaxial wetting test. The results indicate the model can reflect the deformation behavior of loess in one dimensional compression test and the relation between collapsibility coefficient and vertical pressure in one dimensional wetting test. It can simulate the variation of volumetric strain during shearing under different consolidation pressure, the variation of initial elastic modulus with confining pressure in conventional triaxial compression test and the wetting induced deformation law in triaxial wetting test. The effect of bonding element parameter on mechanical character is apparent. The breakage law obtained by DEM experiments is more reasonable than the existing law for triaxial compression test with strain-hardening behavior.