Numerical study of the stability of a partially saturated soil slope

The paper presents a numerical study of the behaviour of a cut slope in partially saturated soil. The mechanical behaviour of the soil was modelled using a generalised constitutive model for partially and fully saturated soils which relates shear strength to the soil-water characteristic curve of the soil. Finite element analyses were performed for different initial groundwater table depths with the soil above the groundwater table treated as either dry or unsaturated. The analyses were repeated in order to obtain the critical angle of shearing resistance corresponding to slope failure for each case analysed. This angle was then used to calculate the Factor of Safety of the slope. The analyses demonstrated that both the depth of the phreatic surface and the consideration of partial saturation have a significant effect on the calculated factor of safety. The soil-water characteristic curve was found to have a small effect on slope stability.