Analysis of the seepage process in clay slopes intercepted by trench drains

Pore pressures in soils decrease the effective stress level and consequently the shear strength on the slip surface, so reducing the slope safety factor against sliding. Then, drainage systems are involved to limit this dangerous condition. The numerical solution of the equations governing the seepage phenomenon is not straightforward because of the non-linearities involved and possible moving boundaries in the computational domain. Then, the choice of appropriate mathematical models makes the phenomenon to be simulated and numerically evaluated with different orders of accuracy depending on both the exemplification introduced into the model and the computational method chosen.In this paper the two-dimensional seepage problem is considered, for which an efficient and simple second-order accurate in space (and first order in time) implicit finite difference scheme has been set up, capable both to rapidly compute the steady-state solution and to accurately represent the unsteady seepage.