Control of Water-Flowing Fracture Development with Solid Backfill Mining: Designing a Backfill Body Compression Ratio for Water Resources Protection

Abstract

Coal development in China is shifting to its ecologically-vulnerable western regions where the loss of water resources is a major problem with respect to protecting the ecological environment. The results of physical similarity simulation tests showed that the movement and deformation of the strata above the stope with cave mining created a ‘domino effect’, which caused further interconnected fractures and loss of water resources. On that basis, we propose the use of solid backfill mining (SBM) to actively control the development of water-flowing fractures. Moreover, a mechanical model describing the development of water-flowing fractures in the overlying strata under SBM was established, the evaluation criteria and method were defined, and the variation rule of the height of water-flowing fractured zone with the backfill body compression ratio was derived. Finally, a case study was performed in an experimental coal mine in Shaanxi. After engineering the design, the minimum critical backfill body compression ratio corresponding to no water resource loss with SBM was calculated to be 21.3%. The field measured data (103.7 m) was very consistent with the results of the mechanical calculation (106.9 m), verifying the accuracy and reliability of the mechanical model. This research can help protect water resources and further enhance coal recovery.