Preventive measures for rainfall-induced slope failures in Singapore

Climatic changes result in dynamic flux boundary conditions across slope surfaces, such as infiltration and evaporation. As a result, stability of a slope as quantified by factor of safety (FoS) is not constant over time, but it varies in accordance with variation in flux boundary conditions. In other words, slopes are infrastructures whose stability is highly dependent on the environment and whose failure has detrimental impacts on environment and public safety. Therefore proper analysis and selection of preventive measure for residual soil slopes in Singapore is imperative, especially in anticipation of global climatic changes which will have an impact on the stability of many residual soil slopes in Singapore. This chapter focuses on the numerical analyses of residual soil slopes incorporating unsaturated soil mechanics and extreme rainfall conditions in Singapore. Typical unsaturated soil properties for high and low permeability of soils in Singapore were used in the analyses. The adaptation measures using vegetative cover and capillary barrier system are recommended to achieve a minimum FoS of 1.5 for residual soil slopes in Singapore.