Abstract: 80 soil-structure contact surface specimen tests are conducted by a refitted DSJ-2 electric quadruple equal stress direct shear device, which involve five contact types such as soil-soil，soil-smooth concrete，soil-rough concrete，soil-parallel veined wood，soil-vertical veined wood.As a result, shearing stress-strain curves for the contact interface between soil and different structures at various moistures and normal stresses are obtained.The result shows that the mechanical properties of soil-structure contact surface such as shear strength，friction angle and cohesion force are closely related with soil moisture, structure material and structure roughness.

Key words: Contact surface, shear characteristic, Moisture, Roughness