Research On Shear Failure Characteristics And Anchoring Mechanism Of Penetrating Standard JRC Joints

In the construction process of underground engineering,we often encounter rock masses with different morphological characteristics.With the increasing volume of infrastructure construction in recent years,the construction requirements are getting more higher,and the construction problems is getting more difficulty.It affects the construction of the project.especially the rock mass with penetrating joint.This paper summarizes the previous theoretical research,combined with experiments,particle flow code(PFC)and theoretical calculation of JRC roughness characterization method.Research for the macro and micro damage mechanisms of the rock mass with penetration standard roughness joints under no anchoring and anchoring conditions.The main results are as follows:(1)The shearing conditions of the rock in the unanchored and unjointed state were researched.The experimental specimens were used as the comparison group,and the shearing results of the specimens with three different anchoring forms and four different anchoring roughness were compared.(2)For the three anchors with different elongations under the same roughness conditions,the average improvement of shear strength can be up to about 35%.With the decrease of elongation,the percentage increase of shear strength of anchored specimens is Gradually decrease,and when the specimen is anchored with high elongation,the specimen is stable at the residual strength stage,and it is not easy to cause brittle fracture,which causes the joint surfaces to move rapidly and the strength is reduced rapidly.(3)For the specimens under the same anchoring condition,compared with the flat joint non-anchor specimens,with the increase of the joint roughness of the specimens,the shear strength is gradually increased,and the increase of the shear strength is gradually increased shear strength can reach up to about 40%.It is found that the effect of roughness on shear strength is more obvious than different anchoring conditions.(4)On the basis of the above-mentioned laboratory experiments,and using PFC to verify the correctness of the experiment with the same scale model.Observation and monitoring of fracture development and failure process from micro-perspective by numerical simulation based on discrete element method.The analysis angle mainly focuses on particle analysis,displacement analysis,force chain analysis,contact force analysis,etc.,and analyzes the microscopic damage morphology of the specimen from the variation of the particle dispersion,the numerical change of the cloud image and the change of the internal force.(5)On the basis of previous studies,and by using the exponential function,Gaussian function,polynomial function,Fourier function,sine function five kinds of function approximation methods for the JRC standard roughness joint curve,it can find that the sine function is more appropriate to descripe the fluctuation of the joint.Although the fitting degree will decrease as the complexity of the joint surface curve increases,the erro of the fitting degree is smaller than the other four fitting functions,and the calculation process is relatively simple compared to the Gaussian function and the Fourier function.And characterize the fluctuation of the joint surface well.(6)Through further calculation it is found that the fitting function can characterize the joint fluctuation and reduce the error accumulation better.At the same time,the JRC roughness calculation method based on the fitting function is accurate to based on the discrete point-based calculation method.Therefore,a new JRC roughness calculation method is proposed based on the sine function.