Utilization status of underground space of mine remains and application prospect of structural filling technology

Intensive coal mining in China has generated vast underground voids, whose resource utilization holds significant implications for alleviating land pressure, preventing secondary disasters, and achieving carbon neutrality goals. This paper systematically reviews current comprehensive utilization technologies for coal underground spaces, examines research progress in CO₂ geological sequestration and underground reservoir technologies, and analyzes critical challenges and development prospects through the lens of structural backfill technology proposed by our research team. Existing studies reveal that while CO₂ sequestration via industrial solid waste mineralization shows promise, critical issues persist regarding the permeability and long-term stability of carbon fixation materials, along with unclear damage mechanisms of reservoir surrounding rocks under multi-field coupling effects. Underground reservoir technology constructs water storage systems through goaf modification, yet faces critical challenges of cyclic hydraulic pressure-induced wet-dry fatigue in dam structures. Structural backfill technology establishes stable underground structures through low backfill ratio and high-stability designs, providing mechanical guarantees for functional space utilization, but confronts bottlenecks including undefined critical backfill positions, material performance-function mismatches, unclear multi-field coupling mechanisms, and insufficient intelligent processes. Future research should prioritize functional backfill material development, cross-scale THMC multi-field coupling modeling, and intelligent perception-digital twin integration to establish a technical system encompassing “geological precision detection-functional orientation design-dynamic optimization control”. Through interdisciplinary collaboration, policy support, and standardization efforts, this study aims to transform underground voids from environmental burdens into strategic resources, providing theoretical and technical foundations for green mining transition and carbon neutrality achievement.