黄土的湿载结构性本构模型研究

土结构性是土结构空间排列几何特征和联结特征所表现出的力学性质，是影响土力学特性的重要内在因素。它与土的密度、粒度、湿度相联系，能够综合反映土的强度、变形等力学特性的变化和发展。从综合反映增湿导致土结构内在主动变化和加载变形导致土结构被动变化两个方面出发，沿用土综合结构势的应力比结构性参数，首先建立压缩、剪切及增湿作用下黄土的结构性演化规律；其次，通过压剪湿作用下黄土的应力-应变特性、屈服破坏特性及其与结构性之间的关系，揭示结构性变化对土力学性质的影响；进而，建立了反映压剪湿作用下黄土结构性发展演化的湿载结构性本构模型。最后通过与试验数据、修正剑桥模型的比较分析，初步验证该模型的准确性。

A structural constitutive model for loess under the wetting condition

Soil structure is one of the physical properties of the soil, which represents the spatial arrangement of soil particles and the type of inter-granular cementation, and it plays an important role in influencing the mechanical properties of collapsible loess. As it is closely linked with density, particle and moisture, the soil structural can reflect the change of the mechanical properties such as strength and deformation. The structural variations induced by either the passively wetting or the positively loading are investigated, with adopting the stress ratio structural index that accounts for the overall structural potential of the soil. Firstly, the structural evolution of loess is determined under compression, shearing and wetting conditions; then the effect of structure on the soil behavior is characterized by establishing a correlation among the stress-strain behavior, yielding and failure behaviors and the soil structures; finally, the structural constitutive relationship of loess under wetting and loading conditions is developed. The proposed model is validated by comparing the numerical results with the experimental data and the results of the modified Cam Clay model.