Abstract This paper presents a physically-motivated micromechanical damage model for describing short- and long-term behaviors of saturated quasi-brittle rocks under drained condition. Rocks are considered composed of a pores-weakened elastic solid matrix and distributed microcracks. The system free energy is determined with the Mori-Tanaka homogenization method. Two main dissipative mechanisms, inelastic deformation due to frictional sliding and damage by crack propagation, are involved and strongly coupled in both stress-loading phases and creep phases under constant stresses. The effect of pore pressure is taken into account in the damage-friction coupling context. The microcracks induced rock damage is divided into two parts: instantaneous damage related directly to stress-induced microcrack growth, and time-dependent damage caused by subcritical cracking. The short- and long-term strengths of saturated brittle rocks are analytically deduced by damage-friction coupling analysis. By using the long-term strength, the creep parameter is calibrated in terms of a critical stress state identified in experiment. Comparisons between model’s predictions and laboratory tests are performed for two typical quasi-brittle rocks under triaxial compression tests and triaxial compression creep tests. It is shown that the proposed model can capture the main features of the mechanical behavior of quasi-brittle materials.

中文翻译：

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饱和准脆性岩石短期和长期行为的微观力学模拟

摘要 本文提出了一种物理激励的微机械损伤模型，用于描述排水条件下饱和准脆性岩石的短期和长期行为。岩石被认为是由孔隙减弱的弹性固体基质和分布的微裂纹组成。系统自由能通过 Mori-Tanaka 均质化方法确定。两种主要的耗散机制，摩擦滑动引起的非弹性变形和裂纹扩展造成的损坏，在恒定应力下的应力加载阶段和蠕变阶段都涉及并强耦合。在损伤摩擦耦合环境中考虑了孔隙压力的影响。微裂纹引起的岩石损伤分为两部分：与应力引起的微裂纹扩展直接相关的瞬时损伤，和由亚临界裂纹引起的时间相关损坏。饱和脆性岩石的短期和长期强度是通过损伤摩擦耦合分析推导出来的。通过使用长期强度，蠕变参数根据实验中确定的临界应力状态进行校准。对两种典型的准脆性岩石在三轴压缩试验和三轴压缩蠕变试验下进行了模型预测和室内试验的比较。结果表明，所提出的模型可以捕捉准脆性材料力学行为的主要特征。蠕变参数根据实验中确定的临界应力状态进行校准。对两种典型的准脆性岩石在三轴压缩试验和三轴压缩蠕变试验下进行了模型预测和室内试验的比较。结果表明，所提出的模型可以捕捉准脆性材料力学行为的主要特征。蠕变参数根据实验中确定的临界应力状态进行校准。对两种典型的准脆性岩石在三轴压缩试验和三轴压缩蠕变试验下进行了模型预测和室内试验的比较。结果表明，所提出的模型可以捕捉准脆性材料力学行为的主要特征。