Analysis of Progressive Failure between Soil and Structure Interface in the Direct Shear Test Using a New Method

Abstract In recent years, the trend of landslide disasters increases year by year with the rapid development of economic construction. The landslide caused massive casualties and economic losses. In this paper, a new kind of stress-displacement sensor, which can monitor the stress and displacement of local points on the contact surface, is developed. A large indoor direct shear test of the contact surface between red clay in Chongqing and structure is carried out by using this sensor. Furthermore, stress and deformation response evolution characteristics of the contact surface under shear loads and different soil compactness and normal stress are discussed. The shear failure of the contact surface between soil and structure is characterized by progressive failure; the normal stress of the contact surface and the compaction degree of the soil has a significant influence on the progressive failure. The test results indicate that the peak stress along the shear direction of the contact surfaces shows obvious inhomogeneity features. Considering the progressive failure characteristics of soil, the shear strength parameters obtained by the traditional large direct shear test underestimated the soil shear strength before the peak shear stress of shear curves. Then, in the post-peak shear stress stage (post-failure zone), the residual strength obtained by large direct shear tests represents the real residual strength of the soil.