Abstract: It is vital to accurately represent the bearing performance of rock bolts in numerical simulations for rock bolt support design.In order to simulate the tensile-shear coupling failure model of rock bolts in FLAC3D,this paper adopts Fish language to modify the Pile structural unit intrinsic constitutive model based on the theoretical criterion of bolt failure,and verifies its validity by numerical simulation and indoor test of bolted joint shear.The applicability of the modified model is analyzed by using the rock bolt support of a roadway at the Xinglongzhuang Coal Mine as the engineering background.The results show that the deformation of the roadway surrounding rock obtained from the modified model simulation is larger,and the shear and axial force of the rock bolt of the original model maintained at a higher level,while the shear and axial force of the modified model drop to zero after reaching the rock bolt failure condition.The simulation results under the modified model condition are more consistent with the field reality in contrast to the built-in model in FLAC3D.Due to the abundance of joints in the engineering rock,the use of theoriginal model of Pile structural unit to simulate the support will result in inaccurate evaluation of the support effect,which will lead to engineering disasters such as instability of the surrounding rock.Hence,it is necessary to consider the tensile-shear coupling failure mode of the rock bolt.