Experimental study on shear performance of saw-tooth rock joint with weak interlayer under different moisture contents and filling degrees

Abstract

Rock joints are important factors affecting natural disasters such as landslides, and weak interlayer is the decisive factor for rock joint stability. Therefore, it is necessary to carry out shear test research on rock joints with weak interlayer. In this paper, the red sandstone was used as rock joint material, and consistent saw-tooth rock joints were produced by the 3D carving technology. According to the on-site composition analysis, the weak interlayer used in the test was obtained through remodeling. Weak interlayer with different moisture contents and filling degrees were produced by the Constant Dry Mass Method (CDMM). Shear strength test of rock joint with weak interlayer of different filling degree and moisture content under multi-level normal stress was carried out by the self-developed direct shear apparatus. The test results show that peak shear strength of rock joint with weak interlayer increases firstly and then decreases with the raise of moisture content. Peak shear strength of rock joint with weak interlayer decreases firstly and then tends to a stable value with the raise of filling degree. As the filling degree of weak interlayer changes from small (less than 1.0) to large (more than 1.0), dilatancy mode of saw-tooth rock joint changes from dilatation to contraction during shearing. Peak shear strength of rock joint with weak interlayer increases with the raise of normal stress.