Regional stability and adaptation measures slope failures due to rainfall in Singapore

Abstract

As heavier rainfall intensities are expected in the future, it is important to employ preventive measures for anticipated possibility of residual soil slope failures. This study primarily focuses on the principles of unsaturated soil mechanics to establish an appropriate framework for adaptation measures against extreme rainfall conditions. These adaptation measures consist of the development and evaluation of slope susceptibility maps as well as the planting of vegetation for critical slopes based on regional stability analyses of residual soils within Bukit Timah Granite and Old Alluvium in Singapore. In this study, slope susceptibility maps were developed for three zones of residual soils within Bukit Timah Granite and Old Alluvium in Singapore. The pore-water pressure distributions and factors of safety (FS) within each zone were obtained from Transient Rainfall Infiltration and Grid-Based Regional Slope Stability Analysis (TRIGRS) and Scoops3D, respectively. Results from the slope susceptibility maps were verified against 2-D numerical analyses. The 2-D numerical models were verified through instrumentation data. The results from slope susceptibility maps agreed with the results from 2-D numerical analyses. In addition, the inclusion of vegetation at the slope face was concluded to be an effective slope stabilisation measure from the simulated 2-D numerical analyses.