A micromechanics-based constitutive model is formulated to describe the nonlinear elastoplastic behaviors of frozen sands. In the model, frozen soils are conceptualized as two-phase materials, in which the first phase is regarded as virgin/undamaged frozen soil specimen including the components of soil particles, ice crystals, and partial water with elastic–brittle behaviors (bonded elements), and the second phase is treated as fully damaged soil sample including soil particles and unfrozen water with elastoplastic behaviors (frictional elements). The interactions between bonded elements and frictional elements are well considered in the representative volume element within the framework of continuum micromechanics and homogenization theory. Moreover, the non-uniform distribution of strain is taken into account and the breakage process is considered due to the structural degradation/loss of ice crystals in the representative volume element. It is found that the ice crystals are gradually breaking up and then melting into unfrozen water with the increase of external loads, so at the moment the bonded elements are considered to transform into frictional elements and then both elements bear the external loads collectively. A novel binary-medium constitutive model is established by the Mori–Tanaka technique and then validated by two groups of laboratory tests about frozen soils and unfrozen sands under conventional triaxial compression conditions. Eventually, the predictions demonstrate that the theoretical calibrations are well in agreement with the available experimental stress–strain responses.

中文翻译：

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基于均质化理论的冻砂弹塑性微观力学本构模型

建立了一个基于微观力学的本构模型来描述冻砂的非线性弹塑性行为。在模型中，冻土被概念化为两相材料，其中第一相被视为原始/未损坏的冻土试样，包括土壤颗粒、冰晶和具有弹性-脆性行为的部分水（结合元素）的成分，第二阶段被视为完全损坏的土壤样品，包括土壤颗粒和具有弹塑性行为（摩擦元素）的未冻结水。在连续介质微观力学和均质化理论的框架内，在代表性体积单元中很好地考虑了结合单元和摩擦单元之间的相互作用。而且，考虑了应变的非均匀分布，并考虑了由于代表性体积元素中冰晶的结构退化/损失而导致的断裂过程。发现随着外载荷的增加，冰晶逐渐破碎，然后融化成未冻结的水，因此此时认为结合元件转变为摩擦元件，然后两个元件共同承受外载荷。Mori-Tanaka 技术建立了一个新的二元介质本构模型，然后通过两组常规三轴压缩条件下冻土和未冻砂的实验室试验进行验证。最终，预测表明理论校准与可用的实验应力应变响应非常一致。