Study On Shear Characteristics Of Sawtooth Rock Structural Plane Based On Particle Discrete Element Method

The rock structural plane plays a decisive role in the stability of the engineering rock mass,and the failure mechanism of the rock mass is controlled by the structural plane to a great extent,it's of great theoretical and engineering significance to study the shear characteristics of the rock mass.Due to the indoor test of rock structure plane is difficult to sample,andthe test repeatability is poor,so in this paper,using theparticleflowsoftware(PFC5.0),establishthe direct shear model of two-dimensional particle flow,base on the uniaxial compression numerical test and the direct shear numerical test,demarcate the micrometer parameters of model.In view of the change of micro parameters in PFC5.0 version,study the influence of parameter variation on the macro mechanical properties of the model,and carry out the sensitivity analysis;then carry out thedirect shear test usingsawtooth rock structural planewithdifferent undulate angle and anti-undulate angle in different method to the numerical value of stress and shear rates,comprehensively analyzethe shear behavior of sawtooth structure plane under different internal and external conditions;finally,studythe shear mechanism of the sawtooth structure plane from the microscopic dynamic point of view.The research results enrich the modeling method of particle flow discrete element model,and also provide reference for the study of mechanical properties of sawtooth rock structural planes.The main results of this paper are as follows:(1)According to the PFC5.0 changes in micro parameters,base on the uniaxial compressive and flat structural plane shear test,study the influence of the change of above microscopic parameters on the macroscopic mechanical properties of the structural plane,thenfit the parallel tensile bond strength(pb_ten)of microscopic parameters and uniaxial compressive strength peak macroscopic parameters relationship curves,and obtained the fitting relationship;lastly summarizes the macro mechanical parameters on the sensitivity of micro parameters,and sortthe sensitivity of the microscopic parameters.(2)Aiming at the sawtooth structure plane shear mechanical characteristics,using PFC5.0 software in the smooth joint contact model to characterize the mechanical properties of structural planes,baseon single sawtooth and multi-sawtooth structure surface numerical direct shear test,by changing the structure model of the internal and external conditions,obtains the peak shear stress and residual shear stress values of the structural plane model under different wave shapes,normal stress and shear rate,analyzes the shear properties of sawtooth structure plane in different internal and external conditions(3)Aiming at the sawtooth structure of the micro cutting mechanism,base on the particle flow software to obtain the structural plane particle displacement vector change diagram and the microcrack expansion map,analyzethe difference between the different fluctuation degree and the different normal stress on the shear fracture mechanism of the sawtooth structure surface straight shear model?The results show that,the shear failure of the sawtooth structural plane is divided into three kinds of failure modes,such as wear and tear damage along the slip surface,local through shear failure and overall through shear failure.With the increase of the sawtooth structure surface fluctuation and the normal stress,the failure mode of the sawtooth structural surface gradually evolves from the wear failure of the sliding surface of the structural plane to the overall penetration.