Rainfall-induced Failures of Residual Soil Slopes with Spatial Variability of Hydraulic Conductivity

Abstract

Abstract-The aim of this paper was to examine the effect of spatial variability of hydraulic conductivity, commonly existing in nature, on rainfall-induced failures of residual soil slopes. Parametric study was carried out at typically residual soil slopes with two distinctively different types of hydraulic conductivity, high (k s =10 -4 m/s) and low (k s =10 -6 m/s) conductivity, in Singapore. Finite element method was applied in this slope stability analysis using commercial SVFlux and SVSlope software in a couple manner. Rainfall intensity was varied as a fraction of the hydraulic conductivity. As a result, greater spatial variability of saturated hydraulic conductivity affects more noticeably the instability of both high and low-conductivity soil slopes exposed to high-rainfall intensity (I > 0.05 k s for high-conductivity slopes and I >1 k s for low-conductivity slopes). However, there was a negligible effect of spatial variability of hydraulic conductivity on the instability of slopes subjected to low-rainfall intensity, even this spatial variability tended to slightly increase the stability of high-conductivity slopes.

Rainfall-Induced Hydraulic Properties for Unsaturated Soil in Klang Valley

“…From the previous observation, it is found that hydraulic conductivity of soil is the main role in rainfall-induced failures of the slopes. Moreover, it was stated that residual soil slopes have experienced a very long and severe weathering process consequently these slopes are potentially susceptible to instability [9].…”