Shear strength of granitic residual soil in saturated and unsaturated conditions

Abstract

Over the last 40 years there has been increasing interest in the mechanical behaviour (i.e. the shear strength and volume change behaviour) of unsaturated soils. However, there is still a lack of a good representative and comprehensive shear strength analytical model. Researchers have been trying to link the volume change behaviour to the shear strength; however there are still shortcomings in the existing frameworks. They have been developed from the standpoint of stress-strain behaviour. Thus, an experimental procedure for the laboratory test were performed by carrying out series of consolidated drained triaxial tests on saturated and unsaturated specimens of diameter 50mm and 100mm height. The test equipment involved a conventional and a double-walled triaxial cell, and the test material was granitic residual soil grade V. The results underlined the shear strength behaviour of the test material with respect to net stress and suction and showed a good match with the proposed shear strength model. It has been found that the apparent shear strength for unsaturated soil due to the force of suction exists and thus can increase the strength of the whole soil skeleton as shown and prove in the tabulated tables.