Relationship between Shear Strength and Suction of Granitic Residual Soil

Rainfall is very important elements in slope failure. Rainfall infiltrating into the slope is the main factor that triggers slope failure. The infiltration of the surface water affects both resisting and disturbing components of the slope which in turn decrease the slope stability factor. Shear strength parameters are very important for design slope and foundation. In this study, Consolidated Drained (CD) triaxial test were conducted on granitic residual soil specimens, both under saturated and unsaturated conditions with different moisture content at 16%, 17% and 18%. While, the Soil Water Characteristic Curve (SWCC) were developed using the pressure plate extractor apparatus and gives a result of residual suction, 148 kPa which equivalent to maximum apparent cohesion, 17 kPa. Therefore the shear strength variation with respect to suction was found to be non-linear for the entire test in accordance to the curved surface envelope soil shear strength model (CSESSM).