Effect of pore-size distribution on unsaturated shear strength of residual soil from granitic Bukit Timah formation

• Main Author: Ang, Qimou
• Other Authors: Harianto Rahardjo
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Civil engineering::Geotechnical
• Online Access: http://hdl.handle.net/10356/15877
• Institution: Nanyang Technological University

Singapore’s land comprises mostly residual soils. The residual soil from the Bukit Timah granitic formation is often found in an unsaturated condition. Soil-water characteristic curve (SWCC) of the soil shows how weathering grade has affected the pore-size distribution of the residual soil. The objective of the project is to investigate the effect of pore-size distribution on unsaturated shear strength of residual soil of the Bukit Timah granitic formation. The experiments were carried out by estimating pore-size distribution using SWCC and measuring unsaturated shear strength parameters using triaxial apparatus of two specimens. The tested residual soils contain mostly silt and clay with a low percentage of coarse content. The effective angle of internal friction ϕ’, was found to be around 27° for both specimens while the ϕb angles were found to be very different at 58° and 83°. SWCC results showed that the air-entry value for both specimens is around 5kPa and they have different pore-size distribution. Overall, pore-size distribution can be used to estimate unsaturated shear strength of residual soil of the Bukit Timah granitic formation as there was a reasonable amount of correlation. This report discusses in detail the findings and outcomes of the study.