Abstract: Large deformations in tunnel surrounding rocks can easily lead to tension, shear, and tension-shear frac? ture of the anchor bolts. In view of this, this paper modifies the mechanical behaviors of the PILE structure unit based on the FLAC3D software and establishes a numerical simulation model for fracturing of PILE unit through the secondary development of FISH language. On such basis, it analyzes the mechanical behaviors of the fracture failure of anchor bolts in the anchorage system of the layered rock mass. The results show that: (1) the calculation results obtained by modifying the PILE unit are in good agreement with the indoor test results and can better reflect the mechanical behaviors of tension, shear and tension-shear fracture of the anchor bolts; (2) in the case of anchor bolt fracture in the layered rock mass, the maximum tensile force to which the tensile fractured anchor bolt is subjected reaches its ultimate tensile value before anchor bolt fracture; the maximum tensile and shear forces of tension-shear fractured anchor bolts are less than the corresponding ultimate tensile and shear values before fracture; and (3) for tension-shear fractured anchor bolts, if the shear fracture of the anchor bolts is not taken into consideration, it would exaggerate the support effect of the anchor bolts; while for tensile fractured anchor bolts, not considering the effect of shear fracture has a limited impact on the support effect of the anchor bolts.