Modeling study on influence of surface pore water on slope stability of mountain tunnel

In order to solve the problems of slope strength reduction and stability risks caused by excessive surface water in mountain tunnels, the influence of surface pore water on slope stability is deeply studied. This article first analyzes the seepage field of unsaturated soil. Taking the transient seepage field as the object, the distribution of the soil seepage field during the two-stage precipitation process is studied. Secondly, the existing dimensionless second-order partial differential equation is solved by Laplace transform to calculate the distribution of transient seepage field. A finite element model of rock and soil seepage field under different rainfall intensities was established, and the influence of pore water content on slope stability was quantitatively analyzed. The results show that as the anti-sliding force decreases, the pore water content increases, the pressure increases, the suction force of the matrix decreases, the shear strength decreases, and the slope safety factor decreases, which leads to the plastic deformation of the slope.