Modelling unsaturated soil slopes subjected to wetting and drying cycles

Abstract

Water infiltration changes the pore pressure distribution in unsaturated slopes leading to slope movement, and therefore has been one of the most common triggering mechanisms for landslides in tropical areas. Field monitoring data suggest that seasonal wetting and drying cycles cause gradual and progressive downward slope deformation, despite the fact that limited upward movement also occurs in dry seasons. This paper presents a numerical study aimed at examining the deformation and stress path characteristics in an unsaturated slope subjected to wetting and drying cycles. The results demonstrate that progressive deformation is caused by plastic deformation when the stress path of a soil element intercepts the failure criterion during wetting. The amount of plastic strain varies with locations, and depends on the initial stress state of the soil element as well as the amount of pore pressure change. The global behaviour of the slope is largely affected by stress re-distribution. © 2008 Taylor & Francis Group, London.