Water disaster prevention and control of coal seam mining under thick roof sandstone aquifer: theory and technology

The coal seams in the Huanglong Coalfield are overlain by the thick sandstone aquifer of the Luohe Formation. This aquifer features abundant groundwater reserves and sufficient recharge, leading to severe water inrush hazards from the roof during coal mining. Consequently, the technology for preventing and controlling roof water hazards has become a critical technical challenge restricting safe mine production. To comprehensively analyze the current status of water inrush disasters prevention and control in coal mining under the extremely thick roof sandstone aquifer in the Huanglong Coalfield, and explore the key research directions for roof water inrush disasters prevention and control based on new technologies in the future, the research progress of water inrush disasters prevention and control in the extremely thick composite roof sandstone aquifer in the Huanglong Coalfield in recent years was comprehensively summarized from the perspective of water inrush disasters prevention theory and technology. Based on the characteristics of roof water inrush disasters during coal seam mining in the Huanglong Coalfield, roof water inflow patterns can be broadly categorized into three major classes and six specific types. Among these, continuous high-flow water hazards, as well as pulsed water inflow and bed-separation-induced water inrush under the non-continuous inflow category, constitute the primary forms of hazards. In theory, by summarizing the water sources, channels, water inrush signs, roof structure, aquifer recharge-runoff-discharge conditions, roof overlying rock breakage, and water conduction channel evolution caused by water inrush disasters in extremely thick roof sandstone aquifers, it has been clarified that under the influence of high-intensity mining, the research status of the development of water fissure zones develops significantly, with a maximum fracture-to-mining height ratio exceeding 30. The direct connection of this zone with the aquifer has been identified as the cause of continuous water inflow. The dual effects of aquifer recharge and mining extrusion are the cause of pulse-type water inrush disasters caused by the formation of detachment space in the intersection area of the curved subsidence zone of the overlying rock and the fissure zone. Overall, the deformation and inrush disasters characteristics of the overlying rock and the water inrush disasters disaster mechanism under strong mining conditions have been clarified. From a technical perspective, through the analysis of existing water-conducting cracks based on the advantages and disadvantages of technologies such as interstitial zone development height exploration, aquifer hydrogeological parameter acquisition, and water inrush disasters control for extremely thick roof sandstone aquifers, it is proposed that “groundwater interception” combined with long-distance directional drilling and targeted sounding technology to form a “source-cutting, centralized drainage” is a technical system that can effectively prevent and control water inrush in extremely thick roof sandstone aquifers. Furthermore, the direction for developing a multi-source intelligent monitoring and early warning technology within this technical framework has been clarified. On the basis of summarizing the current theories and technologies for water inrush disasters prevention and control in extremely thick roof sandstone aquifers, combined with cutting-edge development directions, it was clarified that the Huanglong Coalfield is still facing problems such as the unclear mechanism of water release from the complex flow path of separated layer water under strong mining conditions and the disaster-causing mechanism. It pointed out the key development directions in the future in terms of deep-seated water inrush mechanism, high-precision detection and monitoring, research and development of new grouting materials, water-retaining mining and ecological protection, as well as mine water resource utilization and intelligent hazard prevention and control.