Effect of Slope Geometries on 3D Slope Stability under the Influence of Infiltration

Rainfall-induced slope failure is the most common type of slope failure in Malaysia. Many studies have been carried out to assess the correlation of infiltration to 2D geometric features such as slope inclination. However, the relationship between infiltration and 3D slope geometric features has not yet been widely studied. The aim of this study is to assess the effect of varying slope geometries on slope stability with the influence of rainfall, and to compare the results of the 2D and 3D slope analysis. Seepage and slope stability analysis of homogenous slopes for normal, curved surface and turning corner slopes of varying angles were modelled using the numerical software PLAXIS LE.  The 3D analysis demonstrated that multiple shallow failures spread across the sloped surface, which could not be captured by the 2D analysis. The failure modes are similar for the various geometric types of slopes.  The results also indicate that the safety factor from the 3D analysis decreases more significantly with the rainfall duration as compared to the 2D analysis. This study changes the perception that a 2D analysis is more conservative than a 3D analysis, which is not always true.