Abstract:
The scarce water resources and fragile ecological environment in western mining regions are insufficient to support high-intensity coal mining activities, readily triggering cascading ecological damage including groundwater depletion and vegetation degradation. To achieve the dual objectives of coal development and aquifer protection in these ecologically fragile western mining regions, a comprehensive technical framework for the entire process of underground “water-preserved mining” is constructed. This framework, based on the “water-preserved mining” concept and integrating previous research findings with engineering practice, encompasses “source investigation and assessment – process optimization for loss reduction – multi-level prevention and control of mining-induced damage”. Engineering implementation is conducted at the Yushuquan Coal Mine in Xinjiang. Source investigation and assessment: The spatial configuration relationships between coal seams and aquifers/aquitards are determined based on geophysical exploration results. Aquifers are categorized by importance using aquifer protection level evaluation indicators, identifying the burnt rock aquifer as the core protection target of the groundwater system at Yushuquan Coal Mine. Laboratory tests reveal the burnt rock exhibits a dualistic characteristic of “strong macro-conductivity versus weak micro-permeability”. Its significant brittleness and tendency for sudden failure present a water inrush risk following mining disturbance. Process optimization for loss reduction: The development height of the water-conducting fracture zone is predicted using empirical formulas and key stratum theory. Mining methods and parameters are designed through similarity simulations and numerical modeling to suppress fracture zone development. Aquifer damage levels following mining of the lower No. 10 coal seam are classified based on structural integrity. Damage-tiered prevention and control: Targeted protection measures are formulated for aquifers at different damage levels: Groundwater transfer and storage for severely damaged zones; Aquitard modification and reinforcement before mining combined with post-mining grouting for in-situ aquifer reconstruction in moderately damaged zones; Self-recovery via chemical precipitation for slightly damaged zones. Practice demonstrates that application of the entire-process technical framework for underground water-preserved mining effectively protects the burnt rock aquifer at Yushuquan Mine, maintains its structural integrity, and reduces water resource depletion.