Potential for mine water disposal in coal seam goaf: Investigation of storage coefficients in the Shendong mining area

Abstract

Abstract Water resource shortages and coal mine water disposal create major challenges faced by Northwest China. This study investigated the idea of building underground reservoirs in coal seam goaf after coal mining activities in support of water resource protection and use. Several underground reservoirs have already been successfully constructed in the Shendong mining area. To inform reservoir construction, a mathematical fluid-solid coupling model was developed for calculating the storage coefficient and reservoir volume. Moreover, the effects of different physical parameters on the underground reservoirs were investigated. In addition, the storage coefficient of the Shendong mining area was calculated, which can contribute to site selection for future water storage facility development in that area. The results show that the rock bulking coefficient and mining height all have significant effects on the storage coefficient, in terms of uncertainty analysis. The storage coefficients in the Shendong mining area ranged from 12.80% to 33.80% (mean 22.30%). The total water storage for 18 typical underground reservoirs is 1857 × 104 m3. The utilization ratio of mine water could increase from less than 25% to more than 90%. The highest storage coefficients for underground reservoirs would be in the boundary region of the Shendong mining area. The presented approach is helpful for improving mine water use and environmental protection and has broad application prospects.