Numerical analysis for shear strength and deformation characteristic of joint plane with complicated surface

The three dimensional numerical model for rock sample with joint plane was built by FLAC3D software, and the effects of different surface shapes and boundary conditions on the shear strength and deformation characteristic of joint plane were analyzed. The analysis results show that, when the undulating angle of joint plane is small, the relationship between shear strength and normal stress is in accordance with Mohr-Coulomb linear criterion. The effect of the undulating angle on cohesion is in larger magnitude than that of undulating angle on friction angle. With the increase of undulating angle, the relationship between shear strength and normal stress is transferred to the non-linear criterion, which can be fitted by parabolic equation with high correlation coefficient, and the failure mode of joint changes from slipping along joint plane to the compound failure model consisted of slipping failure along joint plane and crushing failure through saw tooth. The ratio of peak strength to the residual strength decreases with the increase of the normal stress, and the relationship between them is in accordance with the exponential equation, while the degree of anisotropic characteristic for joint sample decreases, and shear stiffness increases.