Abstract: 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.

Key words: numerical manifold method, fracture seepage, rock slope stability, seepage-deformation coupling