Study Of Stress Effect On Shear Strength Of Double Saw-tooth Structural Plane

The shear strength of rock structural plane is an important index to measure stability of rock mass.As a typical rock structural plane,the saw-tooth plane is an important research object for scholars.The shear strength is related to surface morphology,normal stress and sample size.The research on the stress effect of shear strength of single saw-tooth structure plane can be found from the domestic and foreign literature,but the research on stress effect and size effect of the double saw-tooth structure plane are few.Based on 3D printing technology,a dozen groups of double saw-tooth structure plane templates were made,and model samples were made by the developed mould.The direct shear tests on double saw-tooth structure plane under a series of normal stress were carried out,and double saw-tooth structure plane was established by PFC2 D,the influence of saw-tooth parameters,normal stress and sample size on peak shear strength was analyzed.The main work and conclusions are as follows:Firstly,the direct shear tests of saw-tooth structural plane under different saw-tooth parameters(saw-tooth width,saw-tooth width,saw-tooth number and saw-tooth height)were carried out.With the increase of saw-tooth width and saw-tooth number,the peak shear strength increases;with the increase of saw-tooth width,the peak shear strength decreases.Secondly,the failure mode of double saw-tooth structural plane is related to normal stress and saw-tooth parameters.With the increase of normal stress,the climbing-gnawing and shearing-gnawing occur in turn.The higher the saw-tooth height,the smaller the normal stress is,the greater the saw-tooth width,the greater the normal stress is.Thirdly,the peak shear strength of straight structural plane linearly increases with normal stress,and the stress effect is not significant.The peak shear strength and peak friction angle of the double saw-tooth structural plane have the stress effect,with the increase of normal stress,the peak shear strength nolinearly increases,but the increase rate decreases;the peak friction angle decreases firstly and then tends to be stable.Fourthly,through direct shear test for double saw-tooth structural plane with different sizes,it is found that the peak shear strength decreases with the increase of sample size,and the scale effect is significant.Finally,based on the PFC2 D,the numerical model is established by using the method of filling particle and particle assignment.The study of the peak shear strength of double saw-tooth structural plane was carried out.Compared with the laboratory test results,it is found that the stress effect of them is basically the same.