Abstract

The uppermost zone of tropical residual soil is a zone of unsaturated soil with a unique characteristic. The uppermost zone intensively change from unsaturated-saturated phase, because the intensity of sun heat is high and the intensity of rainfall is much higher than it's soil permeability. A series of research on the unsaturated shear strength of tropical volcanic residual soil were conducted with Triaxial Consolidated Drained Unsaturated (TXCD-UNSAT ) Method. The research is resulted on unsaturated shear strength parameters. These parameters were evaluated with other research's results on unsaturated shear strength. An analysis based on the two methods of constitutive behaviour of unsaturated shear strength: The Two Independent Stress Variable Method and Effective Stress Method was conducted and the results confirm the published data. © 2011 Taylor & Francis Group, London.