Deep underground surrounding rock is often in the true triaxial stress state. Therefore, it is of great practical importance to recognize the short-term stress-strain relationship of progressive failure and the long-term characteristics of creep failure for the design, construction and maintenance of underground engineering in the true triaxial stress state. This paper aims to propose a feasible theoretical model to solve the problem of the constitutive relation and creep characteristics of rocks under true triaxial compression. Starting from the stress intensity factor, an angular parameter on the crack surface is introduced to characterize the true triaxial stress state. Then, the relationship between microcrack length and macroscopic strain is derived by various representations of rock damage, and then the constitutive relation during rock fracture is derived by combining it with the rock strength factor formula. Finally, the creep failure law of rocks is derived by introducing the relationship between the length of subcritical crack growth and time. The rationality of the theoretical model is verified by comparing theories and experiments. The effects of minimum principal stress, intermediate principal stress, and the crack inclination angle on the stress-strain relationship are analyzed, providing an important basis for selecting the stress state for long-term creep behavior. The analysis examines the relationship between creep failure time and principal stress, and discusses the effect of the crack angle on creep failure time and steady-state creep strain rate.

中文翻译：

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用于评估脆性岩石的短期渐进和长期蠕变破坏的真正三轴压缩诱发的微裂纹模型

地下深部围岩往往处于真三轴应力状态。因此，认识渐进破坏的短期应力应变关系和蠕变破坏的长期特征，对于真三轴应力状态下地下工程的设计、施工和维护具有重要的现实意义。本文旨在提出一种可行的理论模型来解决真三轴压缩下岩石的本构关系和蠕变特性问题。从应力强度因子出发，引入裂纹表面的角度参数来表征真实的三轴应力状态。然后，通过岩石损伤的各种表示形式，推导出微裂纹长度与宏观应变之间的关系，再结合岩石强度因子公式推导岩石破裂时的本构关系。最后，通过引入亚临界裂纹扩展长度与时间的关系，推导了岩石的蠕变破坏规律。通过理论与实验的对比验证了理论模型的合理性。分析了最小主应力、中间主应力和裂纹倾角对应力应变关系的影响，为选择长期蠕变行为的应力状态提供了重要依据。分析检验了蠕变失效时间与主应力之间的关系，并讨论了裂纹角度对蠕变失效时间和稳态蠕变应变率的影响。