A study of the slope stability in unsaturated swelling marly clay

Abstract

The analysis of the some experimental field data on the unsaturated unstable slope constituted with a marly clay soil showed that the swelling and collapse phenomena were the origin of the landslide problem. In the studied case, field investigation data and laboratory tests based on the water retention curve determination were analysed. The recorded pore-water pressure field helped us to identify the hydrological conditions. In fact, the wetting and drying cycles involve the total suction and the degree of saturation changes. To predict the shallow slope failure, a constitutive model taking into account the suction effect as well as their dependence on degree of saturation is proposed. It is especially remarkable that the collapse phenomenon is well reproduced when the model incorporates suction changes and saturated preconsolidation stress. The analysis of the slope failure, basing on the field data and the theoretical study, shows the hydraulic and mechanical effects.