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摘要: 为了反映热-力耦合作用下岩石蠕变变形的全过程，依据断裂力学原理提出了岩石裂纹扩展的临界损伤应力和一个新的可描述岩石在稳态蠕变阶段与临界损伤应力相关的非线性黏性分量，在传统西原模型和Burgers模型的基础上，将指数形式的损伤变量、临界损伤应力以及与其有关的非线性黏性分量引入到流变微分方程，通过叠加原理推导了考虑温度效应的单轴和三轴压缩条件下岩石的流变本构关系，建立了岩石的热-力耦合损伤蠕变本构模型。利用不同温度、不同应力条件下花岗岩的三轴蠕变试验曲线和本文蠕变模型的计算曲线进行比较，结果表明本文蠕变模型能够较好地模拟岩石在初始瞬态、稳态和加速蠕变阶段全过程的变形规律，验证了所建模型的有效性和合理性。该模型为分析高温、高应力环境下岩石工程的长期变形和稳定情况提供了理论依据。Abstract: In order to reflect the whole creep deformation process of rock under the coupling thermal-mechanical action, the critical damage stress is derived on the basis of fracture mechanics principle and a new non-linear viscous component correlated to the critical damage stress is proposed to describe the rock creep deformation in the steady stage. The exponential damage variable, critical damage and its related non-linear viscous component are introduced into the rheological differential equation based on the raditional Nishihara creep model and Burgers mode. By using the superposition principle, the rheological constitutive relation of rock is derived under the uniaxial and triaxial compression conditions considering the effect of temperature. The coupling thermal-mechanical damage creep model is established for rock. Comparison is presented between the calculations of this damage creep model and test data of granite under the conditions of different temperatures and stresses. The results show that this damage creep model can well simulate the creep deformation characteristics of rock in the initial creep stage, the steady-state creep stage and the accelerating creep stage, which verifies the validity and rationality of the damage creep model developed in this paper. This model may provide an important theoretical basis for analyzing the long-term stability of rock engineering under the conditions of high temperature and stress.
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