Laboratory Study on Shear Behavior of Unsaturated Granular Soil During Cyclic Suction Loading

Abstract

The investigation of the influence of suction history on volume change and shear strength behavior of unsaturated soil is one important topic in the study of unsaturated soil mechanics. From the view point of some geotechnical problems there is a lack of investigation on the effect of continuous wetting and drying process, (cyclic suction loading), on the mechanical behavior of unsaturated soils. In this paper a quantitative investigation of the shear strength behavior of compacted granular soils were undertaken using modified triaxial apparatus for unsaturated soil. Constant water content, and consolidated drained tests were carried out on specimen after and before undergoing cyclic suction loading. The deformation of the specimen during cyclic suction changes under an isotropic loading, and the shear strength behavior of the soil sheared before and after undergoing suction history were investigated and discussed. From the investigation, it was found that the shear strength of unsaturated soil depends not only on the magnitude of matric suction but also the suction history the soil undergoes. In addition, specimen that undergoes cyclic suction loading is found to have higher peak shear strength.