Design and Application of New Rock Bolt for Large Deformation Roadway Support in Underground Coal Mine

Rock bolt profile has significant influence on the load-transfer mechanism within the rock bolting system. In response to the problem of large deformation of surrounding rock in deep underground mining, this study develops a new type of bolt with a rib spacing of 50 mm suitable for large deformation support of surrounding rock based on in-depth investigation into optimizing the geometric configuration of rebar bolts. The design objective is established with a focus on improving the bolting system's residual strength and energy absorption capacity based on precise control of the failure mode of rock bolting. Laboratory test results demonstrate that the new bolt achieved a 23.8% and 28.2% increase in peak pullout force using Aluminum and PVC sleeves, respectively. System energy absorption capacity increased by 75.5% and 104.4%, respectively. Field tests further confirmed the superior performance of the novel bolt in roof and rib support, exhibiting significantly higher peak pullout force and energy absorption capacity compared to conventional bolts. Industrial trial provided additional validation of the new bolt's support effectiveness. It provides a new solution for roadway support in deep underground mining and has important theoretical significance and practical application.