Deformation Characteristics and Control Technology of Surrounding Rock of Roof Cutting Retaining Roadway in Extremely Soft Thick Seam of Xinyi Coal Mine

In this study, we address the challenges of high dynamic pressure and difficulties in roadway retention in extremely soft and thick coal seams with a Protodyakonov coefficient of 0.35. Taking the 12060 working face of Xinyi Mine as a case study, we employ FLAC3D numerical simulation software to analyze the deformation characteristics of surrounding rock during roof-cutting and roadway retention in extremely soft and thick coal seams. This analysis is based on the roof deflection formula for different regions, and we propose a surrounding rock control technology that integrates roof-cutting and pressure relief along the roof. The results indicate that the influence range of advanced mining on the roadway is approximately 30 m. The boundary of the limit equilibrium zone on both sides of the roadway extends more than 5 m into the coal body, which reduces the supporting effect of the shallow coal side on the roadway roof. This reduction leads to compressive deformation of the sidewalls due to roof pressure. Furthermore, the results demonstrate that the roof layer, after roof-cutting and roadway retention, forms a cantilever beam structure, resulting in significantly larger deformation on the goaf side compared to the solid coal side. Consequently, the roof bends horizontally toward the goaf direction. In this study, we implement directional blasting for roof-cutting and active advanced support technology. Anchor beams are utilized to enhance the support strength of the solid coal roadway side. In addition, dense long anchor cables and hydraulic lifting sheds are installed near the cutting seam on the goaf side to control lateral roof deformation and assist in roof-cutting. These measures effectively mitigate the lateral bending deformation of the roof.