Abstract: Internal erosion of soil resulted from piping, seepage or overtopping is found to be responsible for a large number of hydraulic structure failures. In this research, a method of preparing samples subjected to piping effect is achieved by dissolving water soluble material (glucose) in sandy soil. Qualitative impacts of initial density and confining pressure on the mechanical properties of the disturbed soil were investigated through triaxial compression tests and bender element tests under different initial densities and confining pressures. According to the test results, obvious reduction in shear wave velocity as well as peak shear strength was observed in the eroded specimen, and such reduction intensified along with the increasing of confining pressure and density, while residual strength appeared to be less affected.

Key words: sandy soil, internal erosion, bender element, shear wave velocity, shear strength, triaxial test