Shear behavior of BFRP anchor-jointed rock mass considering inclination angle and pre-tension

In this study, the double-shear tests of anchor-jointed rock mass were carried out to investigate the mechanical behaviors of Basalt Fiber Reinforced Polymer (BFRP) anchor bolt in the joint surface. A total of 21 specimens were prepared and two main influence factors were considered: the inclination angle of the BFRP anchor bolt (0°, 5°, 10°, 15°) and the load level of pre-tension (36, 72, 108 kN). The parametric study and design recommendations for the shear capacity of the joint surface under the BFRP anchor bolt were carried out. The results showed that a larger inclination angle or pre-tension force can improve the shear capacity and reduce the relative dislocation at the joint surface. When the inclination angle was 15°, the ultimate bearing capacity was increased by 51 % compared with that when the inclination angle was 0°. When the pre-tension force was 108 kN, the ultimate bearing capacity was increased by 142 % compared with that without pre-tension force. The analytical study found that Ranjbarnia's formulations were reliable to calculate of the shear capacity at the joint surface. The predicted results showed good agreement with the experimental results, with the relative errors less than 5 % for all groups. Then, by using this analytical model, the design parameters of the BFRP anchor bolt were tentatively determined at demanded shear capacities of 200 kN and 350 kN, respectively.