Numerical Simulation Study on Gob-Side Entry Retaining Technology with High Water Filling Combined with Top Cutting and Pressure Relief in Coal Mining

In view of the problems existing in traditional coal mining methods, such as waste of coal resources, stress concentration in mined-out areas, difficulty in roadway maintenance and potential safety hazards, this study introduced roof cutting and pressure relief technology combined with high water filling (HWF) materials to retain roadway along goaf. By establishing a reasonable numerical model, the influence of different cutting parameters (cutting height, cutting depth and cutting angle) and the performance of HWF material on roadway stability is analyzed. The numerical simulation results show that the pressure relief technology of roof cutting can effectively control the movement and stress of rock strata, and reduce the stress concentration and displacement of surrounding rock of roadway, among which the height of roof cutting has the most significant influence. High-water filling material can quickly fill the goaf, form an effective supporting structure, prevent rock caving and roadway deformation, isolate the influx of harmful gas and dust, and improve the working environment of roadway. The parameter optimization analysis shows that the comprehensive optimization scheme with the best parameter combination can significantly improve the stability of roadway, reduce the roof subsidence and the convergence of roadway side. The field test and verification prove the accuracy of the numerical simulation results, and solve the problems encountered in the actual construction, such as uneven top cutting and insufficient initial strength of the filling body. This study provides a new technical means for coal mining, which is of great significance for improving coal recovery rate, reducing mining cost and improving mine safety conditions.