Swelling and collapse behaviour of unsaturated soils

• Main Author: Loshana, K
• Other Authors: Leong Eng Choon
• Format: Final Year Project
• Language: English
• Published: 2016
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/68161
• Institution: Nanyang Technological University

The change in volume of unsaturated soils is determined by the net normal stress and matric suction which are the two stress state variables. Shrinkage and swelling or collapse of the soil is dependent on the net normal stress and the matric suction. This project presents a comprehensive laboratory investigation on the compressibility of consolidated samples of mixtures of kaolin and bentonite through a series of oedometer tests. The oedometer apparatus was used to carry out the swell and collapse tests. Kaolin was used as the control clayey soil, and it was amended with different contents of bentonite, 0 (kaolin), 10 and 30% (by dry weight basis) to prepare the mixtures. The specimens were first air dried to various water contents and then inundated with water under different net normal stresses in order to study the wetting-induced volume change. The objective of this project was to investigate the transition of swelling and collapse phenomenon as a result of different net normal stresses. The result of this study indicated that the presence of bentonite in the soil mixtures, influence the swelling and collapse behaviour of the mixture. The slopes for the normal and unsaturated compression and recompression are similar under the same degree of saturation while the slopes for the unloading line under saturated and unsaturated conditions are different.