Study On Fine Macroscopic Mechanical Behavior Of Shear Strength And Deformation Characteristics Of Anchorage Joints

Joints play a very important role in the stability of rock mass engineering.There are a lot of discontinuities in rock mass which aggravate the possibility of rock mass deformation and failure.Therefore,it is necessary to support the rock mass timely and effectively after excavation.Anchor as a mature and effective reinforcement method is widely used in engineering rock mass,in anchorage joint rock,the anchor rod by axial forces control the deformation of the joint so as to improve its strength,and in the actual engineering rock mass,as a result of the influence of in-situ stress and rock mass itself weight,often produce relative movement between anchorage joint plane,will make the anchor under large lateral force,joint and bolt interface to produce stress concentration,damage lead to anchor rod anchor rod body function abate,causing the change of the load transfer mechanism of anchor rod,in order to ensure the safety and economy of joint rock anchoring effect,discussed different joint surface morphology,The fine macroscopic mechanical properties and deformation characteristics of joints;Considering the dynamic change law of bolt load transfer mechanism caused by dislocation of joints,it has become an urgent technical problem to establish a numerical calculation unit considering bolt characteristics.In this paper,we study the anchoring under the effect of shear failure characteristics and damage evolution mechanism,analysis of joint shear properties,macros in the form of joint surface microstructure characterization methods,reveals the ultimate load under the action of joint fine macro mechanical response characteristics of each component and the damage evolution process,anchor structure and establish corresponding anchoring joint shear constitutive model.The specific contents are as follows:(1)Based on the strength characteristics and deformation characteristics of joint shear,and by changing the shear strength parameters in joints,the variation rules of joint shear strength with the bonding force and internal friction Angle were studied.(2)The particle flow numerical calculation method was used to establish the joint direct shear numerical simulation calculation model,and the laboratory test results were used to calibrate the numerical calculation parameters to establish the relationship between microscopic parameters and macroscopic mechanical parameters.(3)Based on the research on the influence of microstructure parameters on the macroscopic shear mechanical behavior of joints,the quantitative relationship between microstructure mechanical parameters and macroscopic mechanical behavior is established by changing such parameters as normal stiffness of particles,tangential stiffness of particles,friction coefficient and thickness of structural surface.(4)Based on rock mesoscopic parameters on no anchor shear mechanical behavior studies the influence of structural plane,this paper discusses the structural plane shear mechanical behavior with particle contact modulus,particle contact stiffness ratio,bond,bond stiffness modulus ratio,normal bond strength,parallel bond cohesive force,friction coefficient and particle radius,etc.8 mesoscopic parameters change rule.(5)By comparing the direct shear test results of structural plane with and without anchor,the influences of four microscopic parameters,namely normal stiffness of particles,tangential stiffness of particles,friction coefficient and thickness of structural plane,on shear mechanical behaviors of structural plane are studied.(6)Based on the study on the influence of rock meso parameters on shear mechanical behavior of structural plane with anchor,the influences of 8 meso parameters,such as particle contact modulus,particle contact stiffness ratio,bond modulus,bond stiffness ratio,normal bond strength,parallel bond cohesion force,friction coefficient and particle radius,were emphatically analyzed.(7)According to the pressure-shear state of anchorage joints,two kinds of joint models with different roughness are established by using two-dimensional particle flow program,and anchor rods with different anchorage angles are set by self-compiled fish program to study the direct shear characteristics of anchorage joints under different normal loads.(8)According to the tension-shear state of anchorage joints,six anchorage numerical models are established by using the particle flow numerical method,and the shear mechanical characteristics of joints at different anchorage angles are obtained.(9)Taking the rock slope anchoring project of zhangjiajie to huayuan expressway as an example,this paper analyzes the distribution rule of axial force along the bolt length,and discusses the reinforcement effect of different bolt layout on the jointed rock slope.