Coal seam grouting location investigation based on advanced abutment pressure distribution in large mining height working faces

Abstract Roof collapse and coal wall instability pose significant safety risks in large mining height working faces, impacting production efficiency and equipment utilisation. Currently, an effective method for dealing with wall instability and roof caving involves grouting reinforcement of fragmented coal bodies. Understanding the distribution law of advanced abutment pressure under mining influence at the working face and identifying the elastic zone, plastic zone, and stress concentration peaks helps determine the location of grouting reinforcement. This study investigates the advanced abutment pressure distribution law and investigates the coal seam grouting optimum location to mitigate these risks. Through theoretical analysis, numerical simulation, and field measurements, it comprehensively reveals the elastic-plastic zoning and stress concentration characteristics ahead of the coal wall. The research indicates that the plastic zone length is 5.2 m, the elastic zone length is 8.5 m, and the total advanced abutment pressure distribution range is 13.7 m. With the excavation of the roadway, the range of advanced abutment pressure distribution remains basically unchanged while the stress peak increases. The stress on the low-horizontal side of both walls is higher, and the stress distribution at the coal wall exhibits a “saddle shape”. A precise grouting reinforcement scheme based on the distribution law of advanced abutment pressure is proposed and implemented on-site, enabling pre-reinforcement of the coal seam, improving stability, and reducing the occurrence of accidents in coal wall instability and roof caving areas by 80%.