Experimental research on optimization of anchorage bearing characteristics based on bolt pull-out test

In order to improve the bearing capacity of bolt support in the deep soft rock roadways and effectively control the deformation of the surrounding rock of the roadway, the bolt pull-out orthogonal test was used to study the influencing factors of the anchor bearing characteristics and analyzed the effects of different influencing factors. Based on the test results, the high-prestress full-length anchoring support technology was proposed, and then the prestressed full-length anchor bolt was developed, and the analysis was carried out based on Pansan Coal Mine 17102 (3). The return air roadway of the working face was used as the engineering background, and the numerical simulation and field test methods were used to compare and verify the traditional lengthened anchor support and full-length anchor support. The research shows that the pull-out failure of the anchor rod first occurs at the bonding interface between the anchor and the test block, and the pull-out anchor failure of the bolt has undergone a dynamic stage of elasticity-plasticity-destruction. Different anchoring factors produce different anchoring effects, and their manifestations are also different. Among them, the strength of the test block and the prestress of the bolt have a significant influence on the ultimate pull-out force of the bolt, and the magnitude of the ultimate pullout force is positively correlated with the strength and prestress of the test specimen. According to the test results, the high-prestressed full-length anchor bolt support technology is proposed. The developed pre-stressed full-length anchor bolt adopts full-length anchoring to improve the strength of the rock mass while applying pre-stress in sections. Compared with the traditional lengthening anchor support and full-length anchor support, the high prestressed full-length anchor support technology realizes the transfer of prestress to the surrounding rock on the basis of full-length anchorage of the bolt, thereby increasing the range of the surrounding rock compressive stress zone and forming a more effective anchoring bearing structure of surrounding rock. Engineering practice shows that the pre-stressed full-length anchoring support technology can effectively control the large deformation of the surrounding rock in the deep broken soft rock roadway, and realize the stability control of the surrounding rock in the deep roadway.