Equivalent elastic model and strength properties for cross-jointed rock mass containing persistent and non-persistent joints

Based on the method of the equivalent elastic model,the composite damage model was constructed to consid-er comprehensively the mac-roscopic and microscopic defects of the rock mass containing persistent and non-persistent joints. Firstly,the part of persistent joint was considered as an independent material with a certain thickness,which mainly produces closed deformation and shear deformation along the joint surface,which can store elastic strain energy and shear strain energy. Secondly,based on the combination of fracture mechanic and strain energy theory,the non-persistent joint rock part of the cross joint was regarded as the internal macro damage of rock mass. Therefore,the joint point of stress intensity factor was calculated,and the formula of strain energy stored in non-persistent joint was de-rived. The microscopic damage was described according to the Weibull distribution within the rock mass,and the com-prehensive consideration macro and micro defects of joint rock damage model was established. Thirdly,the strength cri-terion of cross jointed rock mass was discussed,and the equivalent elastic model of different strength criterion was con-structed. Finally,the calculated results were compared with the test results,the model calculation results are in good agreement with the experiment results,which proves the rationality of the model. In addition,the influence of persistent joint angle and non-persistent joint angle on the peak strength and failure criterion of rock mass,and the influence law of initial damage variables affected by penetration rate of non-persistent joint were discussed.