Experimental Study On Shear Deformation And Fracture Characteristics Of Granite Under Three-dimension Stress

Rock is a kind of heterogeneous mineral which is composed of many minerals.In nature and engineering,the stress state of rock is very complex.One of the main failure modes of rock mass is shear failure,including shear and shear.It is very difficult to study the fracture characteristics of rock under different stress states because of the great difference of the fracture law.In view of the above analysis,this paper makes the experimental study on damage characteristics of granite under the single shear force and double shear different stress,different stress state characteristics of each stage shear force displacement curve of the combined with acoustic emission technology,to further explore the emission characteristics of each stage in the process of rock failure,and with the help of 3D laser scanner and shear and the surface morphology,to better grasp the regularity of rock fracture.Through the study found:(1)Double shear granite single shear and low normal stress rupture process,the shear stress displacement curves can be roughly divided into 4 stages: the period of load adjustment(OA),the elastic deformation section(AB),elastic-plastic deformation section(BD),peak deformation(DE).But the double shear process,when the normal stress is greater than 50 MPa,such as 70 MPa,granite rupture process of the shear stress displacement curve has a long period of intensive plastic deformation,showed strong plasticity.(2)The single shear failure process of granite,with the increase of normal stress,shear strength and residual shear strength,elastic deformation of slope and the ratio of peak strength and residual strength were gradually increased rock peak,the single shear friction coefficient of granite decreases gradually.(3)The failure process of granite double shear,with the increase of normal stress,shear strength and residual shear strength gradually increased rock peak,elastic deformation of slope and the peak strength and residual strength ratio decreases,the friction coefficient of double shear increases first and then decreases.(4)In the granite single shear process,with the increase of normal stress,the peak shear strength of shear stress to granite,AE counts and energy increases first and then decreases,the cumulative AE counts and energy accumulation decreased gradually.(5)In the granite double shear process,with the increase of normal stress,the peak shear strength of shear stress to granite,acoustic emission counts,energy and energy accumulation increased gradually,the cumulative AE countsdecreased first and then increased.(6)After single shear and double shear failure,with the increase of normal stress,the value of (?) decreases.It is shown that the larger the normal stress is,the smaller the shear surface asperity is.