基于温度-应力耦合作用的岩石时效蠕变模型

基于岩石变形与热力学基本理论，建立了温度-应力耦合作用下脆性岩石时效蠕变损伤模型。根据此模型，在有限元数值软件COMSOL的基础上进行二次开发，考虑岩石介质的非均匀性，并以最大拉应力准则以及摩尔库仑准则为岩石单元的破坏准则，给出了温度-应力耦合作用下岩石时效蠕变损伤模型的数值求解方法。并结合室内实验结果验证了该模型方法的可行性和合理性。数值模拟结果表明该模型能准确描述不同温度条件下花岗岩典型蠕变全过程三个阶段，即初始蠕变阶段、稳态蠕变阶段和加速蠕变阶段。数值模拟也表明声发射累计数和岩石轴向应变的演化趋势整体上具有一致性，且在初始蠕变阶段和加速蠕变阶段出现较多的声发射现象。

A TIME-DEPENDENT THERMO-MECHANICAL CREEP MODEL OF ROCK

A coupled thermo-mechanical creep model of brittle rocks under constant temperatures is proposed based on the theory of rock deformation and thermodynamics. In the model, the heterogeneity of the rock is incorporated. Both the maximum tensile stress criterion and Mohr-Coulomb criterion are used to control tensile damage and shear damage in brittle rocks, and finite element formulation is implemented into COMSOL Multiphysics. A series of numerical simulations are performed and the numerical model is validated against experimental data. Numerical simulations show that the proposed model well captures the typical three creep stages, i.e., primary creep, secondary creep, and tertiary creep of rocks under different constant temperatures. Moreover, numerically simulated cumulative AE counts is consistent with the trend in axial strain of rock, and there are clusters of AE counts during the initial primary creep stage and the tertiary creep stage.