Rock-like materials demonstrate significant induced anisotropy due to intricate micro-structural evolution under external loading, where their effective mechanical behaviors over short and long durations are heavily contingent upon the growth and subcritical expansion of microcracks. In this study, we introduce a novel unified constitutive model aimed at describing the anisotropic damage and time-dependent mechanical properties of rock-like materials, while accounting for nonuniform microcrack growth. The constitutive model is formulated within the framework of irreversible thermodynamics and Mori–Tanaka homogenization. Plastic deformation is attributed to frictional sliding along oriented microcracks, while instantaneous and time-dependent damage evolution are driven by crack growth and subcritical cracking, respectively. More specifically, we develop analytical solutions for instantaneous stress–strain, creep strain-time, and relaxation stress-time relationships under compression. Finally, we validate the performance of the proposed anisotropic time-dependent model against experimental data obtained from tests conducted on Beishan granite and gray sandstone.

中文翻译：

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一种新颖的微机械各向异性弹塑性损伤模型，用于了解类岩石材料的时间相关行为


由于外部载荷下复杂的微观结构演化，类岩石材料表现出显着的诱导各向异性，其短期和长期的有效机械行为在很大程度上取决于微裂纹的生长和亚临界扩展。在这项研究中，我们引入了一种新颖的统一本构模型，旨在描述类岩石材料的各向异性损伤和随时间变化的力学性能，同时考虑不均匀的微裂纹扩展。本构模型是在不可逆热力学和 Mori-Tanaka 均质化的框架内制定的。塑性变形归因于沿定向微裂纹的摩擦滑动，而瞬时和时间相关的损伤演化分别由裂纹扩展和亚临界裂纹驱动。更具体地说，我们开发了压缩下瞬时应力-应变、蠕变应变-时间和松弛应力-时间关系的分析解决方案。最后，我们根据在北山花岗岩和灰色砂岩上进行的测试获得的实验数据验证了所提出的各向异性时间相关模型的性能。