Macro-mesoscopic Research On Shear Test Of New Composite Bolted Joint Rocks And CZM-FEM Simulation

The new composite materials have been widely used in important fields such as concrete structure and highway transportation with the rapid development of large-scale civil engineering construction in China.However,the bolted mechanism and analysis methods of the new composite materials are still not completed,and the deformation characteristics and engineering design are still unclear.As a result,there are few cases about SFCB and BFRP applied in engineering,which become the block for their development.In this paper,macroscopic and microscopic research on shear mechanics characteristics and crack evolution mechanism of new type composite bolted joints are carried out,which based on the previous research results,combined with laboratory shear test and CZM-FEM.The results show that:(1)Based on the laboratory test,the characteristics of joint and the normal strength on the shear strength of bolted rocks are obtained.The shear strength of jointed rocks growth with the increase of roughness and normal load.(2)It was found that SFCB bolted rocks have the highest strength,followed by HRB400.BFRP would cause brittle failure of jointed rocks and have the lowest shear strength.Therefore,this material should be avoided to be used for shear resistance support of jointed rocks in engineering.(3)The ABAQUS finite element CZM method is creatively used to simulate and analyze the shear test,and the shear process of jointed rocks is reproduced by the simulation method of embedding the global zero-thickness cohesive elements,which has good consistency with the test,and provides a new analysis method for the shear simulation study of bolted jointed rock mass.(4)Numerical analysis results show that the smooth joint will appear shear slip failure in the shear process under normal load,the joint with large fluctuation is prone to local shear failure and the joint with many teeth is appeared as the incision-type failure.(5)The axial strength,shear strength,bending moment and crack evolution in the shear process of different bolt materials are analyzed.It is revealed that the high tensile strength and Young's modulus of SFCB bars are the reason for the high shear strength,while the reason for the brittle failure of BFRP is that there is no obvious yield point and the Young's modulus is low.The BFRP bar only plays a role in resisting "drawing" in the process of bolted shear,resulting in brittle fracture of jointed rocks.