Unsaturated Properties of Singapore Urban Soils

The geology of Singapore mainly consists of three formations: Jurong Formation, Bukit Timah Granite, and Old Alluvium. Under the tropical and humid climate, unsaturated residual soils are commonly found in Singapore, and are formed by in situ weathering of their parent rocks. The properties of residual soils from these three formations are different. In this chapter, the physical properties, including typical ranges of particle sizes, Atterberg limits, soil-water characteristic curves, permeabilities, and shear strength parameters of these three residual soils are presented together with a description of their significances. The summarized soil properties are based on laboratory measurements from soil samples obtained from various locations in Singapore. In this chapter, an introduction to the three general geological formations in Singapore is first made. This is followed by the basic definitions used in geotechnical engineering to index and classify soil, together with the summary of soil characteristics for the three formations in Singapore. Finally, the typical unsaturated soil properties in the three formations is elaborated.