Experimental Study On Shear Behavior Of Grouted Reinforcement Structure In Fractured Rock Mass

Grouting reinforcement technology can effectively control the deformation of surrounding rock and significantly improve the support effect.It shows great potential in the surrounding rock control system of the roadway and has been widely used in the maintenance of broken roadway in coal mines.At present,research on grouting reinforcement effect mainly focuses on grouting process and material strength.Only the effect of grouting material strength on the grouting effect is considered,but the control problem of grouting material cost is neglected.There is not enough research on the grouting effect between different strength grouting materials and different strength fractured rock masses.In view of this,it is of great engineering significance to carry out research on the relationship between grouting material strength and rock mass strength.In this aiticle,five kinds of water-cement ratio grouting materials of 0.6~1.5:1 are selected to grout and strengthen the structural planes of different strength fractured rock masses.And the depth relationship between grouting material strength and rock mass strength is explored through the structural plane shear characteristics test.The research content mainly includes four aspects: Shear deformation feature,shear strength characteristics,shear parameter analysis and structural plane shear failure characteristics.(1)The shear stress-displacement curve of the intact rock mass undergoes the elastic deformation stage,the yield stage and the softening stage.The shear stressdisplacement curve of the fractured rock mass without grouting shows the friction slip stage.The post-peak characteristics of the grouting structure surface of the fractured rock mass are closely related to the strength of the grouting material.The post-peak curve stage is characterized by the low rise of the grouting material strength: friction slip stage,post-peak softening stage,shear slip stage.(2)The smaller the strength of the rock sample,the more obvious the grouting reinforcement effect of the fractured rock mass structure is compared with the ungrouting,indicating that the grouting can greatly enhance the shear performance of the rock mass.The greater the strength of the rock sample,although the grouting can improve the shear resistance of the rock mass,the increase of the shear strength of the grouting reinforcement structure surface is smaller than that of the unslurryed shear strength.The degree of increase in the shear strength of the grouted structural plane is higher under low normal stress and lower under high normal stress.The main reason is that the shear strength of the un-grouted structural surface is low at low normal stress,and the grouting reinforcement structure has the largest increase.(3)When the strength of grouting material is close to the strength of rock sample,the shear strength of fractured rock mass structure increases most rapidly with the increase of material strength;after the strength of the grouting material exceeds the strength of the rock sample,the shear strength of the fractured rock mass structure surface continues to increase as the strength of the grouting material increases,but the rate of increase slows.The improvement of the grouting material reinforcement effect is most obvious when the strength of the grouting material is slightly higher than the strength of the rock sample.(4)With the increase of grouting material strength,the deformation and failure of grouting structure surface changes from plastic slip type to brittle shear type.With the increase of normal stress,the failure mode changes from the intact type to the broken type,and the shearing property of the structural surface is enhanced after grouting.