ABSTRACT
The design of soil-structure interfaces is often dominated by the shear strength of the interface, which is affected by seasonal variations (e.g. water table, precipitation) of the soil moisture content. Since unsaturated soils behave differently under drying and wetting (i.e. hysteresis), this research investigates the influence of stress history (i.e. cyclic suction or hysteresis) on the unsaturated interface shearing behavior. To this end, direct shear tests results were conducted on suction-controlled rough interfaces under cyclic suction (drying/wetting). Rough steel interface tests were conducted using cohesionless silt. Results indicated that the interface shear strength is dependent on the suction-stress history of the soil. For a given suction, specimens that underwent cyclic suction (i.e. drying followed by wetting) showed higher peak shear strength than those undergoing drying only prior to shearing.
