基于TOUGHREACT的岩石水力损伤耦合数值模型研究

Numerical model for hydro-mechanical-damage coupling of rocks based on TOUGHREACT

从细观力学角度出发,充分考虑水-力耦合条件下岩石细观特征及其演化,结合热力学理论,建立基于TOUGHREACT的岩石细观水力损伤耦合数值模型。模型可较好地考虑任意微裂纹滑移剪胀、损伤扩展和法向压缩闭合等细观力学行为对岩石宏观变形破坏、渗透性演化和水流运动过程的影响。采用室内煤岩注水破坏试验成果对数值模型的正确性和有效性进行验证,进而开展现场尺度下岩石注水响应的应用模拟研究。模拟结果表明,注水引起的岩石损伤与压力增高区的分布同时受注入流量、现场应力水平与初始微裂纹各向异性分布等因素的影响。岩石宏观水力耦合响应的模拟有赖于内部微裂纹结构的准确表征。研究成果对深化岩石水力耦合研究具有一定参考意义。

For better modelling the microscopic characteristics and evolution of materials under hydro-mechanical coupling conditions, a TOUGHREACT-based hydro-mechanical-damage coupled numerical model for saturated rocks is established by using the microscopic homogenization method and the thermodynamics theory. The proposed model well accounts for the influences of sliding dilatancy, damage propagation and normal compression of arbitrary microcracks on the macroscopic deformation and failure characteristics, permeability evolution and fluid flow process. The numerical method is successfully validated through the experimental data of water injection tests on coal sample at the laboratory scale and then used to carry out application simulations of water injection responses at the field scale. The numerical simulation results demonstrate that the distributions of injection-induced rock damage and elevated pressure are affected by the injection rate, in-situ stresses and anisotropic distribution of the initial microcracks, and they are more developed in the directions with larger in-situ stress and dominant development of microcracks. Better simulations of the macroscopic hydro-mechanical responses of rocks depend on the accurate characterization of the internal microscopic structures. The research may provide a useful reference for deepening the study on hydro-mechanical coupling of rocks.