Three-dimensional seismic stability of unsaturated soil slopes using a semi-analytical method

Abstract

Seismic stability analyses of soil slopes are routinely performed with dry and/or saturated assumptions under two-dimensional (2D) conditions. However, in practice, soils are often unsaturated and slopes usually fail in 3D fashion. Three-dimensional (3D) effect and suction-induced effect are essential to be considered to produce more realistic solutions in the slope stability analyses. In this regard, an analytical framework is developed in this paper for assessing the 3D seismic stability of unsaturated soil slopes. A semi-analytical method including the simplified method (SM) and the layer-wise summation method (LSM) is developed to deal with the highly variable nature of suction. The validity of the analytical framework in assessing the soil slope stability is checked with published solutions. Examples are given to illustrate the 3D effect and the effect of suction on the slope seismic stability. The described framework allows the user to quantify the effect of changes in moisture content on effective stress distribution and effective unit weight distribution in the slope and thus, changes in the slope stability.