Relationship of Collapse Potential and Swell Pressure with Suction of Unsaturated Expansive Soil

Expansive soils in unsaturated state cause problems to several civil engineering structures due to its transient volume change behavior. Present study is focused on evaluation of swelling and collapsible characteristics of unsaturated compacted expansive soil specimens and their relationship with suction. A series of volume change swell pressure tests and double oedometer tests were conducted at varying degree of saturation to evaluate swelling pressure and collapse potential of Bharuch expansive soil respectively. Suction measurements of soil were conducted by employing WP4C Dew point Potentiameter at different water content. Presence of higher negative pore pressure induced higher swelling pressure, which was observed to vary exponentially with total suction. Results indicated significant influence of soil suction on soil fabric arrangement, which substantially affected collapse behaviour of expansive soil. Collapse potential of Bharuch expansive soil was observed to decrease with increase in water content due to reduction in suction of soil indicating metastable state of soil at lower degree of saturation.