Numerical analyses and monitoring performance of residual soil slopes.

Abstract

Changes in the pore-water pressure of unsaturated soil slopes due to rainwater infiltration comprise a crucial factor which affects the shear strenght of soils and may trigger slope failures. Two residual soil slopes in two main geological formations in Singaproe, the Bukit Timah Granite and the sedimentatry Jurong Formation, were fully instumented. Real-time monitoring systems were developed to examine the pore-water pressure, the rainfall and the groundwater level of the slopes for over a year. The characteristics of the pore-water pressure distributions in both slopes during rainfall were highlighted and compared. The monitoring results indicate that the residual soil slope of the Bukit Timah Granite has a thicker unsaturated zone due to a deeper groundwater table than the residual soil slope of the sedimentatry Jurong Formation. A higher permeability fo the residual soil of the Bukit Timah Granite results in more rapid changes in negative pore-water pressure due to rainwater infiltration than the residual soil of the semimentary Jurong Formation.