Water hazard prevention technology for confined mining beneath dual extremely thin aquicludes in roof and floor

Abstract With the intensifying depletion of coal resources, water hazard prevention and control for confined coal seam mining—characterized by ultra-thin aquicludes in both roof and floor adjacent to dual confined aquifers—has become a critical challenge. Taking the 9101 working face of Mine A as the research object, this study aimed to address the complex geological conditions of dual ultra-thin aquicludes and dual confined aquifers. Through FLAC3D numerical simulation, we compared the surrounding rock deformation and failure characteristics of four mining schemes, namely Fully Mechanized Coal Mining, Regional Grouting Mining, Backfill Mining, and the Coupled Application of Regional Grouting and Backfill Mining, and further evaluated their applicability for water hazard prevention. The results demonstrate that each single scheme has inherent limitations, whereas only the coupled scheme can achieve synergistic control of roof and floor water hazards. Specifically, after implementing the integrated prevention and control system of Regional Grouting Mining – Backfill Mining – Structural Grouting Reinforcement in actual mining, the failure heights of the roof and floor were reduced to 12.39 m and 4.12 m, respectively. Microseismic monitoring and water pressure loss testing verified the accuracy and applicability of this integrated technology. This study confirms the feasibility of confined mining under the conditions of dual ultra-thin aquicludes, and provides an optimized strategy for the safe and efficient extraction of coal seams under similar hydrogeological settings.