Variation of small strain stiffness for piping-influenced Toyoura sand

Landslides triggered by piping are frequently reported during stormy periods. Despite large amount of model tests related with internal erosion, there is little research on the mechanical properties of disturbed soil by means of element experiment. In this paper, an attempt was made to create artificial piping by dissolving water soluble material (glucose) in sand. Chains of voids were generated when water was infiltrated and drained out through the specimen. Small torsional cyclic loadings were conducted on the hollow cylindrical specimens in order to obtain the small strain stiffness of the soil before/after piping erosion. According to the results, reduction of shear modulus was found in specimen with internal pipes after water infiltration, and piping-induced anisotropy was found to be obvious.