Research on Key Parameters for Relieving Pressure on Roofs of Deep Mine Cutting and Retaining Roadways

Scientific and reasonable roof-cutting parameters are key to ensuring pressure relief of the retained roadway roof. This manuscript takes the 7135 working face of Qidong Coal Mine as the engineering background and uses theoretical analysis, numerical and on-site measurement methods to study the quantitative relationship and pressure relief effect between different roof-cutting parameters of GERRC. We established a fracture criterion based on the tensile strength of the main roof of the uncut joint along the cutting line. We analyzed the quantitative relationship between different main roof thickness, cutting height, cutting angle, and the main roof tensile stress of the uncut joint. We found that within a small range of cutting angles, as the cutting angle decreases, the tensile stress on the main roof of the uncut joint increases. When the cutting angle is 0, the main roof tensile stress of the uncut joint reaches its maximum. As the cutting height increases, the limitation of the cutting angle on the cutting height becomes smaller. Numerical simulation was conducted to study the distribution patterns of maximum and minimum principal stresses along the direction of the roadway roof during the retention period under different roof-cutting heights and angles. Based on this, the optimal unloading effect of the roadway roof and the minimum concentration of mining stress were obtained at a roof-cutting height of 9 m and a roof-cutting angle of 80°. Through on-site measurement of the stress on the reinforcement anchor cable during the retention period, the deformation of the sinking roadway roof, and the pressure relief control effect of the retained roadway roof, the pressure relief effect and scientific rationality of the design of the cutting height and cutting angle were verified.