Integrated control and sequential verification of deep coal seam floor water inrush hazards

Deep longwall mining in North China-type coalfields is increasingly threatened by water inrush from high-pressure karstic limestone aquifers beneath the coal seam floor. Conventional grouting from underground roadways often has low pressure, short diffusion distances and poor control of hidden faults and collapse columns, so residual water-conducting channels may still trigger serious inflows. This contribution presents an integrated control mode and a quantitative verification framework for deep coal seam floor water hazards. First, a GIS-based multi-criteria assessment of floor failure depth, aquifer pressure and structural complexity is used to delineate high-risk blocks at panel scale. These blocks are treated in advance through coordinated control of water-filled aquifers and water-conducting structures, combining high-capacity directional drilling from the surface with supplementary underground boreholes to grout target limestone aquifers and associated fracture zones ahead of mining. To evaluate the effectiveness of the treatment before face retreat, we establish a sequential verification method that links borehole pressure tests, calculated water-blocking coefficients, repeated mine DC-resistivity surveys, spatial analysis of grouting pressure and volumes, and inspection drilling and inflow monitoring. Application to a >800 m deep longwall panel mining the 11# coal seam shows that inflows from overlying and underlying limestone aquifers were reduced to tens of cubic metres per hour and no floor water inrush occurred during mining. The proposed control–verification scheme provides a transferable engineering model for designing and auditing floor water-hazard management in deep coal mines affected by high-pressure confined aquifers.