基于相场法的水-力耦合作用下裂隙岩体变形破坏机理

探究水-力耦合作用下裂隙岩体的力学响应和破坏机制，对解决水-力耦合工况下岩体工程安全与稳定问题具有重要意义。基于Biot多孔介质理论及弹性理论，提出一种水-力耦合相场数值模拟方法，提出交错时间积分方案来获得流体压力和固体变形的稳定解，得到的控制方程式采用全饱和多孔介质弹性理论的体积应变分离和偏应变分离。通过模拟水力压裂与天然裂隙相互作用等数值算例验证了数值模型的有效性和正确性。此外，为探究实际工程开挖过程中的卸载破坏机理，结合钻孔注液试验数值实例，建立一个裂隙岩体水-力耦合卸载破坏模型，模拟水-力耦合条件下裂隙岩体卸荷破坏全过程。结果表明：在水-力耦合卸载破坏过程中，混合拉-剪裂纹的扩展和连接主导了最终破坏模式；初始围压、初始卸荷应力状态对剪切裂纹的发育具有促进作用，水压则反之。

Phase field modelling of the hydro-mechanical coupling failure mechanisms of fissured rock masses

Exploring the mechanical response and damage mechanism of fractured rocks under hydro-mechanical coupling is one of the important ways to solve the safety and stability problems of rock engineering under hydro-mechanical coupling conditions. Based on Biot porous media theory and elastic theory, a numerical simulation method of hydro-mechanical coupled phase field is developed, and a staggered time integration scheme is proposed to obtain stable solutions of fluid pressure and solid deformation, in which the obtained control equations adopt the volume strain separation and partial strain separation of elasticity theory of fully saturated porous media. Two different numerical examples of fluid permeability tests and hydraulic fracturing with natural fracture interaction are used for validation. By the comparing of the numerical model with the analytical solution, the numerical results and the previous data are in better agreement, which verifies the validity and correctness of the model method. In addition, in order to investigate the unloading damage mechanism in the actual engineering excavation process, a hydro-mechanical coupled unloading damage model was established by combining numerical examples of borehole injection tests to simulate the whole process of fracture rock propagation damage under the dual conditions of hydro-mechanical coupling and surrounding pressure unloading. The study shows that mixed tensile-shear crack expansion and connection dominate the final damage mode during coupled hydro-mechanical unloading damage. Confining pressure and initial unloading stress states have a promoting effect on the development of shear cracks, while water pressure is reversed.