Anchoring performance of bolts in coal-rock composite anchored bodies under various influencing factors

ZHAO Fanghao; GAO Lin; ZHAO Shuang; TANG Shixian; GAO Changsi; MO Feilong

doi:10.11799/ce202505018

Abstract：In order to enhance the anchoring effect of bolts in complex geological conditions of coal-rock roadways,we studied the key influencing factors of bolt anchoring performance for coal-rock roadway support.Firstly,the physical and mechanical parameters of different coal seams and roof-floor strata in typical mines were obtained,and the in-situ stress distribution in the roadway was measured combining with the hollow inclusion stress relief method.Based on field data,a numerical model was established to invert the stress state of the bolt working environment during excavation and mining,and the confining pressure range was determined as 0～15 MPa.Then,through laboratory tests,the influence patterns of different coal-rock strength ratios(1∶2,1∶3,1∶4,1∶5),confining pressures(0,5,10,15 MPa),and cross-layer anchoring methods(coal-to-rock,rock-to-coal)on the load-bearing performance of coal-rock composite anchorages were systematically analyzed.The results indicate that:Increasing the coal-rock strength ratio significantly enhances the ultimate pull-out load of bolts(from 45.4 kN at 1∶2 to 68.79 kN at 1∶5);Under higher confining pressure,the anchorage stability improves with the ultimate load increases from 34.52 kN at 0 MPa to 77.55 kN at 15 MPa;The coal-to-rock anchoring method demonstrates superior performance compared to rock-to-coal,exhibiting delayed interface debonding and higher residual strength.These findings provide theoretical and experimental support for bolt support design in coal-rock roadways under complex geological conditions.