Comparative Study of Transverse Shear Characteristics of Shear-Yielding Bolts and Traditional Bolts Based on Numerical Simulations and Direct Shear Tests

The shear-yielding bolt is a new type of anchoring structure, and its working mechanism in layered rocks is not yet well understood. To investigate its transverse shear characteristics, this paper takes the shear-yielding bolt as the research subject and uses different anchoring states of bolts as variables. A comparative study of shear-yielding bolts and traditional bolts is conducted using the Abaqus numerical simulation software and large-scale direct shear tests. The results show that (1) low-modulus material allows a slight displacement between the structural surface layers, which exerts the friction strength between rock mass layers and avoids stress concentration on the bolt. The shear-yielding bolts reach their peak shear stress in the case of greater displacement, averagely increased by 40% compared to traditional anchor bolts. (2) An increase in the moisture content has less influence on the shear-yielding bolt owing to the material properties. When the moisture content of the structural surface rises from 12% to 20%, for cases where the shear-yielding bolts are used, the peak shear stress decreases by 0.12 kPa, which only accounts for 12% of the original strength. (3) There is an optimum thickness of the low-modulus material in the shear-yielding bolt, considering its effect of releasing shear and the bonding effect between it and the bolt. According to the test results and numerical analysis, the optimum thickness is 15 mm. The results of this research provide a reference and basis for future study and engineering applications of shear-yielding bolts.