Research On Three-dimensional Reconstruction Of Hard Structural Plane And Anisotropic Shear Strength Of Rock Mass

Structural plane refers to the material interface or discontinuous plane with a certain shape and scale in the rock mass,such as cracks,planes,faults and joints,among which the influence of joints on the overall mechanical properties of the rock mass cannot be ignored.In this thesis,the direct shear tests of three kinds of rough joint specimens with different morphologies were designed under different normal stress and shear direction.The change law of shear stress with shear displacement was analyzed,and the failure law of joint surface morphology was explored in the shear process.In this thesis,the reverse reconstruction of joint surface,experimental research,theoretical analysis and model construction are studied systematically.The main contents and achievements are as follows:(1)Obtained the three-dimensional roughness of natural rock joint surface:Firstly,obtained high-precision point cloud data of joint surface based on 3D scanning and 3D printing technology,and then obtained the template of rock joint surface with exactly the same roughness through reverse reconstruction technology.The results showed that a large number of specimens with natural rock joint surface morphology could be made repeatedly,and the shear test of exactly the same joint surface could be realized.(2)Study on the peak shear strength of joint plane: Combined with the shear test results and theoretical analysis of joint plane,considering the climbing and friction effects of rock mass joints along the shear direction,the influencing factors of the peak shear strength of joint plane were discussed,and the mechanism of these factors influencing the peak shear strength was analyzed.The results showed that the threedimensional roughness coefficient of joint surface could be quantitatively calculated by geometric statistical function.Based on the joint plane profile data along the shear direction,the effective coefficient of contact area along the shear direction was proposed to describe the difference of shear strength of rock joints along different shear directions.Accorded to the variation of peak dilatancy Angle with normal stress,the function of peak dilatancy Angle was fitted,and the peak shear strength model considered anisotropy was established.(3)Verification of peak shear strength in numerical simulation: Based on joint surface data of natural morphological characteristics,several joint models with different roughness were established based on Rhino software,and finite difference software FLAC3 D was used for numerical simulation.By monitoring the shear mechanical behavior of joint planes in different shear directions,the morphological characteristics of joint planes and the influence of normal stress on shear strength were analyzed.By comparison,it was found that the shear stress-shear displacement curves of the joint surface were very similar in the simulated direct shear test and the laboratory shear test,which confirms that the convex body on the joint surface had an effect on the shear strength,and verifies the rationality of the test designed in this thesis.