Analysis of the impact of the combined use of rebar bolts and FRP bolts in the roadway enclosure

In order to investigate the support effect of the combination of FRP bolts and rebar bolts in the roadway, taking a coal mine as the background of the project, research and analysis of the engineering geological conditions of the mine and the layout of the mining roadway, stress analysis of the roadway peripheral rock, and put forward the combination of rebar and FRP bolts in the roadway peripheral rock support program. Based on different scenarios, FLAC3D was applied to simulate and analyze the distribution of axial force, maximum principal stress of the surrounding rock, yield damage of the surrounding rock, and displacement of the surrounding rock under three conditions: no support, full rebar bolt support, and combined rebar and FRP bolt support. The results show that (1) In the pre-action period between the bolt and the surrounding rock of the roadway, the FRP bolt carries the force first; in the late action period, the rebar bolt and the FRP bolt carry the force together. (2) From the analysis of the stress concentration degree of the maximum principal stress of the roadway surrounding rock, the horizontal displacement of the roadway surrounding rock and the distribution characteristics of the plastic zone of the roadway surrounding rock, it can be concluded that the support strength of FRP bolts is slightly lower than that of rebar bolts. (3) Under the state of combined support of FRP and rebar bolts, the range of plastic zone of surrounding rock in the roadway is analyzed in comparison with the effect of full rebar bolt support, and the range of reduction of plastic zone of surrounding rock is not obvious, and the effect of full rebar bolt support and combined support of FRP and rebar bolts on controlling the damage of surrounding rock is similar. (4) The side part of the roadway perimeter rock mining adopts FRP bolts instead of rebar bolts, and if the FRP bolts are not damaged, the combination of FRP and rebar bolts can be used for support, which can maintain the stability of the roadway perimeter rock.