| Structural plane is widely existed in rock mass,which causes rock mass to shear slip and become unstable along the structural plane.In engineering,bolt is commonly used to strengthen the structural plane and improve the stability of the rock mass structural plane.However,the coupling effect of the anchored structural surface leads to the change of the performance of the anchored structural surface,and it is difficult to accurately evaluate the shear strength of the anchored structural surface.Therefore,based on the monitoring means of strain gauge and acoustic emission,this paper analyzes the shear characteristics of the structural plane of anchored rock mass,the axial strain and deformation characteristics of anchor rock mass,the failure characteristics of the structural plane of anchored rock mass,and the acoustic emission characteristics of the structural plane of anchored rock mass,and studies the law of the interaction between the structural plane and the bolt.In this paper,the coupling mechanism of anchoring rock mass structural plane is investigated,and the evaluation formula of shear strength of anchoring structural plane based on the coupling mechanism is proposed,and its feasibility is verified.The main contents are as follows:(1)Based on the indoor shear experiment,the shear stress-displacement curve,the shear strength of anchoring and the contribution value of anchored structure under different influencing factors were analyzed.The results show that with the increase of anchoring angle,the equivalent cohesion force and equivalent internal friction angle of the anchored structural surface increase and decrease,respectively.With the increase of normal stress,the shear strength curve of anchored structure surface showed a nonlinear upward trend,and the shear contribution value of the bolt showed nonlinear fluctuations.With the increase of the inclination angle of the sawtooth,the shear strength of the anchored structure showed a nonlinear upward trend,and the shear contribution value of the anchor showed a nonlinear fluctuation.(2)Combined with the acoustic emission method,the energy,RA-AF and acoustic emission b value of the anchored structural surface under different anchoring angles and different normal stresses were compared and analyzed.The results show that with the increase of anchorage angle and normal stress,the time of fracture development in the rock mass continues to move forward,and the energy value increases,compared with the anchoring angle of 60°,the energy value of anchorage angle 75° and 90° increases by 14% and 47%,respectively,and the expansion of the fracture changes from small-scale shear fracture to large-scale shear fracture.(3)By analyzing the deformation and failure law of bolt and rock mass structural surface.It can be concluded that the essence of the coupling effect of anchored structural surface is the additional normal force provided by the bolt on the structural surface during the shear process,which changes the shear force provided by the structural surface.When the anchor does not undergo yield deformation,the main factors affecting the coupling effect of the anchored structural surface are the normal stress and the performance of the anchor itself,and when the anchor is deformed by yield,the bending angle of the anchor will also affect the coupling effect of the anchored structural surface.(4)Based on the structural mechanics and plastic deformation model,the stress of the bolt in the shear process is analyzed,and the shear force provided by the bolt in different stages is obtained.Based on the coupling effect of anchored structural plane,the shear strength formula of anchored structural plane with flat plane and sawtooth Angle plane is proposed. |
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