A Comprehensive Strategy for Safe and Efficient Mining of Thick, Spontaneous Combustion-prone Coal Seams under Geodynamic Hazard Conditions

The Rock bursts represent dangerous dynamic manifestations of rock pressure, the intensity and frequency of which increase with mining depth. The problem of rock bursts is relevant for all leading coal-producing countries worldwide. Addressing this issue becomes significantly more complex when mining seams with coal prone to spontaneous combustion, as it necessitates reliable aerodynamic isolation of mined-out areas. This isolation is typically achieved by leaving pillars with a minimum width of 20 m between extraction panels, which precludes the exclusive use of yield pillars widely employed in mining burst-prone seams. The stable pillars traditionally used in Russia in such cases, with widths of 30-60 m, fail to eliminate the influence of abutment pressure from adjacent previously mined extraction panels. These pillars themselves typically act as stress concentrators and create increased rock burst hazards. Simultaneously, leaving burst-resistant pillars with widths exceeding the abutment pressure zone leads to significant coal losses, as the width of such pillars exceeds 100 m when mining thick seams at depths of 600 m and continues to increase with greater depth. The research objective is to identify promising directions for improving technological schemes of preparation and extraction of longwall panels to enhance efficiency and safety in mining thick, gently dipping coal seams prone to spontaneous combustion under geodynamic hazard conditions. Analysis of global experience in seam extraction under geodynamic hazard conditions has identified a promising approach involving independent preparation of longwall panels using wide barrier pillars between extraction panels (with widths less than the abutment pressure zone and determined based on the stress state of the rock mass). This approach employs an extraction sequence for longwall panels that ensures time displacement of operations between adjacent panels until the completion of primary geomechanical processes in the overlying strata.