Asymmetric deformation characteristics of steep coal-rock interbedded roadway and cross-boundary anchor-grouting combined differential support technology

In order to solve the problem of asymmetric large deformation control of steep coal seam roadway, taking steep coal-rock interbedded roadway in Zhaojiaba Mine as the engineering background, the asymmetric deformation mechanism of steep coal seam roadway was discussed by using the research methods of field observation, theoretical analysis and numerical simulation, and the cross-border bolt-grouting differential support technology was proposed based on the cross-border support principle. The occurrence of steep coal strata leads to the unsymmetrical stress distribution in surrounding rock of roadway, which leads to the shear slip deformation of coal and rock at the top of arc, while the deformation at the top of straight inclined coal is relatively small. Different anchorage lengths and bolting-grouting methods are used to establish the differentiated cross-border support forms on both sides, and the equivalent thick anchor bearing structure of surrounding rock of roadway is constructed. The simulation shows that the surrounding rock stress is optimized, the deformation of roadway is significantly reduced, the settlement of arc roofis reduced by 39.0%, and the convergence of the side wall is reduced by 41.6%. Field industrial verification shows that the maximum crack depth of arc roof is generally reduced from 3.88 m to 1.50 m, which is 61.3% lower, the crack development depth of straight inclined roof is reduced by 47.6%, and the surrounding rock control effect is improved.