耦合渗流-变形的数值流形法裂隙岩质 边坡稳定性分析

Stability analysis of fractured rock slope based on seepage-deformation coupling model using numerical manifold method

岩石裂隙渗流问题作为影响岩石边坡失稳的重要因素吸引了越来越多研究者采用不同的数值方法模拟其力学行为。提出了一种基于渗流-变形耦合模型的数值流形方法,并相应地讨论了岩体裂隙网络中地下水的流动、渗透压力和岩石变形的耦合效应。基于最小能量原理,分别推导渗流条件下单元边界流体压力和系统的整体平衡方程,以及块体接触算法求解任意岩石裂缝的局部安全系数。通过一系列验证实例对所提出的数模模型进行检验,验证了该数值模型的鲁棒性和有效性。利用该方法模拟了一个岩石边坡由于渗流作用而发生的坍塌事故,再现了岩石边坡的破坏过程。模拟结果表明,过大的水力压力导致垂直裂缝张开,增加岩体变形量,最终导致边坡破坏。研究表明,该方法在模拟大规模工程问题方面具有很大的潜力。

Seepage in rock fractures as an important factor affecting the rock slope instability attracts more and more researchers,who have adopted various numerical methods to simulate the mechanical behaviors of slope.In present study,a coupled seepage-deformation model based numerical manifold method(NMM)is proposed,in which the fluid flow of groundwater in fracture network,the coupling effect of seepage pressure and rock deformation are discussed.A global equilibrium equation of system and a local factor of safety of arbitrary rock fractures are derived based on the principle of minimum energy and block contact algorithm,respectively.A two-dimensional flow problem in a homogeneous aquifer and fracture seepage analysis of fluid through regular fracture networks are validated and the simulation results show the robustness and effectiveness of the proposed numerical model.Finally,a collapse accident of rock slope due to seepage effect is simulated by the proposed method and the failure process of the slope is also reproduced.The simulation results show that the excessive hydraulic pressure causes the opening of vertical fractures and augments rock mass deformation,eventually leading to the failure of the slope.It can be found that the proposed method possesses more potential to simulate larger-scale engineering problems.