Abstract: The frictional characteristics of the contact surface between the steel and the coastal plain soils are studied by a modified direct shear device. The results indicate that the shear stress is linearly proportional to the normal stress; at the maximum shear stress, the displacement in the soil is greater than that of in the soilsteel interface. The shear resistance of the soilsteel combination is lower than the shear resistance in soil mass. With the increase of the normal stress, the effect of the bitumen coating will first lower the shear stress and then it will increase the shear stress at the contact surface.

Key words: Modified Direct Shear Device, SoilSteel Contact Surface, Shear Characteristics, Test Devices