Research on Direct Shear Tests and Calculation Methods for BFRP Anchor Rods Reinforcing Rock Joint Surfaces.

BFRP rock bolts have broad application prospects in the field of geotechnical engineering due to their excellent mechanical properties. Large-scale direct shear tests were conducted to explore the shear performance of BFRP rock bolts reinforcing joint surfaces in rock masses. The study analyzed the effects of bolt materials and anchoring angles on the mechanical characteristics of anchored joint surfaces. A theoretical model of bolt shear deformation was established, treating BFRP rock bolts as an anisotropic material. By applying the Tsai-Hill strength criterion, a formula for calculating the shear strength of BFRP-anchored joint surfaces was derived. The results indicate that in the elastic phase, the bolt primarily provides shear resistance similar to a "dowel action," while after yielding, axial constraint effects gradually come into play. The anchoring angle significantly influences the shear strength of BFRP rock bolt anchored blocks, with optimal performance observed around 30°. Under the combined influence of epoxy resin and basalt fibers, BFRP rock bolts exhibit an "expansion-type" fracture under tensile shear loading conditions. The improved method for calculating the shear strength of joint surfaces under tension with BFRP rock bolts aligns well with experimental results. [ABSTRACT FROM AUTHOR]