Stability of unsaturated soil slopes covered with melastoma malabathricum in Singapore

Abstract

Past studies showed that slopes covered with vegetation are less susceptible to rainfall-induced slope failures. This paper focused on unsaturated properties of soil consisting roots of Mangrove and their effects on stability of soil slope from Old Alluvium during rainfall. Melastoma Malabathricum was selected in this study since this Mangrove is best suited for tropical climatic condition. The results of laboratory tests indicated that the air-entry value and shear strength of the soil with roots of Melastoma Malabathricum were higher than those of the soil without roots. The saturated permeability of the soil with roots was lower than that of the soil without roots. The numerical analyses indicated that slope without Melastoma Malabathricum experienced significant decreases in factor of safety during rainfall than slope covered with Melastoma Malabathricum. Hence, Melastoma Malabathricum can be used as a vegetative cover in minimizing rainwater infiltration slope layers with slope angle up to 35o.