基于微观力学机制的各向异性结构性砂土的本构模型研究

在岩土破损力学基础上，基于微观破损机制，提出了考虑各向异性的结构性砂土本构理论。采用Lade-Duncan强度准则考虑中主应力对抗剪强度的影响；采用考虑颗粒排列组构的各向异性状态变量A反映各向异性对土体强度和变形的影响；通过相似扩大重塑土的屈服面反映结构性对土性的影响；通过引入非相关联流动法则考虑各向异性和结构性对土体塑性变形的影响。同时，将基于微观力学机制的损伤演化规律引入结构性土的硬化规律；该硬化规律同时考虑了塑性体积应变和剪切应变对各向异性结构性土强度的影响。然后将该模型用于模拟室内三轴压缩试验，初步验证了该模型的合理性和适用性。

A constitutive model for anisotropic structured sandy soil based on micromechanical mechanism

Based on the framework of damage mechanics for geological materials, a constitutive model is proposed for anisotropic structured sandy soils considering the micromechanism of the destructuring. The Lade-Duncan failure criterion is adopted to consider the effect of intermediate principal stress on the shear strength. An anisotropic state variable A considering the fabric of particle arrangement is employed to reflect the influence of the anisotropy on the mechanical behavior of structured soil. The influence of soil structure on the mechanical behaviors is considered by enlarging the structural yielding surface for reconstituted soils in geometry. The non-associated flow rule is applied to describe a reasonable plastic strain for the anisotropic structured soil. A damage law based on the debonding effect on microscale is used to model the soil destructuring in the hardening law for structured soils. The effect of both plastic volumetric strain and shear strain is considered in the hardening law. Thus, this model can properly describe the mechanical behaviors of soils from intact state to reconstituted state. The proposed model is preliminarily verified by predicting the mechanical behaviors of natural and artificially cemented sands in the triaxial tests.