ASSESSMENT OF THE INFLUENCE OF THE TYPE OF SOIL AND RAINFALL ON THE STABILITY OF UNSATURATED CUT-SLOPES – A CASE STUDY

Abstract

This study aims to evaluate the stability of cut-slopes composing of either low hydraulic
conductivity and high hydraulic conductivity soil under different rainfall conditions. To accomplish this aim,
cut-slopes along Noi Bai - Lao Cai Highway in Yen Bai province, Vietnam were analyzed. A simplified cutslope profile with a homogeneous residual soil layer was used. Specific amounts of rainfall were chosen by
analyzing rainfall data in the study area recorded over a period of 10 years. These amounts were then distributed
evenly to simulate different types of rainfall including small intensity with long duration and high intensity
with short duration. The study used the coupled hydro-mechanical approach to simulate the change of the water
pressure head within the slope during the rain and its consequence on the stability of the slope. The results
indicate that the hydraulic conductivity of the soil and the rainfall conditions have a significant impact on the
stability of unsaturated cut-slopes. For the low hydraulic conductivity soil slope, long-duration rainfall has a
more significant impact on the stability of cut-slopes than high-intensity rainfall while a contrary trend was
found when high-intensity rainfall indicates a greater impact in the case of high hydraulic conductivity soil
slope.