Transient seepage analysis for unsaturated soil

Abstract

Slope failures in residual soils are common in many tropical countries, particularly during periods of intense rainfall. Under an external hydraulic influence, seepage of water can cause a gradual loss of matric suction in an unsaturated soil slope. This has an adverse effect on the soil strength and therefore the stability of the slope. In order to obtain realistic representations of the slope condition under such situation, finite element modeling of groundwater flow is often necessary. It is understood that a physically meaningful solution can only be obtained under fairly restrictive conditions on time step and element size. The combined refinement in spatial and temporal discretisation is generally not achievable on most desktop computing platforms when realistic 2-D and 3-D seepage problems are involved. Various methods to decouple the spatial and temporal discretization effects are studied to achieve a solution that is reasonably accurate and not too computationally expensive.