Bearing characteristics and control measures of coal rib under the condition of composite roof in deep mining

In response to the problem of low bearing capacity of soft coal support in deep mining, which leads to deformation and instability of composite roof, a comprehensive analysis of coal support stability was conducted through on-site research, mechanical analysis, numerical simulation, and in-situ testing methods. Based on the theory of elastic-plastic deformation, a mechanical analysis model for coal seam interface is constructed, and analytical expressions for the stress and width of the coal seam interface in the limit equilibrium zone of the coal seam are derived. The distribution law of the stress and width of the coal seam interface in the limit equilibrium zone under different variables is analyzed. On this basis, based on the deformation and failure characteristics of coal support, a key part mutual stability principle based on "strengthening the rib to consolidate the roof and strengthening the roof to protect the rib" is proposed. Field tests show that the support scheme can ensure the strong support of the roadway foundation, achieve micro disturbance of the roof, and ensure the safe and effective use of the roadway during service.