Experimental Study On Dilation Of Thinly Filled Rock Joint

Rock joints are widely distributed in natural rocks,which are main factors for prediction and control of seepage flow in slopes,dams and underground caverns.According to the Cubic Law,the water flow of rock is influenced by width of joint inside the rock,so that the research for variation of width of joint-dilation-could provide a basis for the stability and seepage characteristics of rock mass engineering.At the same time,due to the effects of weathering,erosion and shear dislocations,a certain thickness of filling material would be generated in the discontinuous structural surface inside the rock mass,which forms the filled rock.And thinly filled rock joints are affected by multiple factors such as boundary conditions,rock joints,and filling media,which shear mechanical characteristics are relatively special.Therefore,select Barton standard profile of rock joint as the section of the rock surface and set up the five-stage filling through indoor shear test and numerical simulation test,for studying on the dilatancy characteristics of thinly filled rock joints,and the main research results are as follows:(1)the thinly filled rock samples were tested by indoor shear test,and the test results show that: in addition to the high JRC of the thinly filled rock joint,due to the damage of the section surface,when infill thickness to asperity height ratio is low,the dilation is small in the shearing process.Meanwhile the shear stress characteristics of rock joint and dilation characteristics are similar to the development of the law,which decrease with filling and the increase of normal stress reduce,and increase with the increase of the roughness of the section surface;(2)Based on the laboratory experiment,the numerical simulation test under the relevant operating conditions was established.From a mesoscopic perspective,it was found that the contact force between the thin-walled rock joint and the filling particles gradually decreases with the increase of shear displacement when the degree of filling is low;When the degree of filling increased,the internal voids of the thinly filled rock joint caused by the misalignment were gradually reduced,the influence on the rock joint shear characteristics and the boundary effect was also gradually reduced;(3)After comprehensive analysis of the effects of filling,normal stress and the roughness of rock joint on the shear characteristics of the thinly filled rock joint,establish the basic determination of the dilation of thinly filling rock joint.At the same time,based on the function of Barton's peak dilation angle of non-filled rock joint,taking into account the reduction effect of filling medium on the roughness of the rock joint surface,the function which predict the dilation angle of thinly filled rock is established is proved to be reasonable and feasible by the results of indoor experiments.