Mining pressure behavior and roadway surrounding rock control in deep weakly cemented soft rock working face

To investigate the law of mining pressure behavior, the characteristics of roadway surrounding rock failure, and the stability control methods of deep weakly cemented soft rock working faces, a typical deep mine weakly cemented soft rock working face in the Huanglong Mining Area is taken as the research object. By comprehensively adopting the methods of theoretical analysis, FLAC^3D and UDEC numerical simulation, and field measurement, this study carries out research on the reasonable width of section coal pillars, the evolution characteristics of advanced abutment pressure in stope, and the surrounding rock control technology of roadways. Based on the limit equilibrium theory, a calculation model for coal pillar width is established, and the reasonable width of the section coal pillar is theoretically determined to be 7.84-9.05 m. The FLAC^3D simulation results show that during the mining process of the 13207 and 13205 working faces, affected by the mining geological conditions of the working faces, the peak value of advanced abutment pressure in the 13205 working face reaches 47.8 MPa, with a maximum stress concentration coefficient of 2.39, which is significantly higher than that of the 13207 working face. The UDEC numerical simulation results indicate that under the original support scheme, the deformation values of the roof, floor, left rib, and right rib of the roadway are 282.3 mm, 44.3 mm, 221.7 mm, and 81.0 mm, respectively. The cumulative convergence of the roof and floor is 326.6 mm, the cumulative convergence of the left and right ribs is 302.7 mm, and the section shrinkage rate is 13.6%, indicating a certain control effect on the surrounding rock. Aiming at the prominent problems of asymmetric deformation of roadway surrounding rock under the influence of secondary mining and the original support scheme, an asymmetric optimized support scheme is proposed. The UDEC simulation results show that under the optimized support scheme, the deformation values of the roof, floor, left rib, and right rib of the roadway are 177.6 mm, 29.7 mm, 101.2 mm, and 54.2 mm, respectively. The cumulative convergence of the roof and floor is 207.3 mm, and the cumulative convergence of the left and right ribs is 155.4 mm, which are further reduced by 36.5% and 48.7% compared with the original support scheme, respectively, and the section shrinkage rate is less than 8%. Meanwhile, the field measurement results show that the roof subsidence of the roadway is less than 200 mm, and the convergence of the two ribs is less than 150 mm, indicating that the deformation of the roadway surrounding rock has been effectively controlled. The research results can provide a certain reference for the safe and efficient mining of weakly cemented soft rock working faces in the Huanglong Mining Area.