1-D settlement characteristics of compacted residual soils

Compacted residual soils are unsaturated in nature. Wetting of unsaturated soil induces soil volume change and even collapse settlement. To investigate the 1-D settlement characteristics of compacted residual soils, double oedometer tests suggested by Jennings and Knight (1957) were conducted on compacted residual soils from Jurong Formation reconstituted with three different kaolin contents. Results from this study showed that soil compacted dry-of-optimum moisture content generally exhibits higher apparent pre-consolidation pressure and lower compression index than soil compacted wet-of-optimum moisture content. This can be explained by the effects of matric suction and soil structure. Reduced compaction effort renders soil more compressible. Soil with higher compressibility generally swells less when inundated. Empirical equation for collapse potential estimation proposed by Lim and Miller (2004) was found to be not applicable to the reconstituted soils in this project. An empirical compression equation that account for soil type, soil structure and degree of saturation proposed by Widiastuti (2005) was verified, and a modification of the relationship between empirical constant η and soil activity A was suggested based on results from this study and past researches. The 1-D settlement behaviour of compacted residual soil can be estimated by using the fully saturated soil compression curve and the empirical compression equation.Bachelor of Engineering (Civil