Analytical method of reservoir capacity of underground reservoir in coal mine: a case study

Abstract

Modern mining within ecologically fragile areas is under enormous pressure from the ecological and geological environment. Using abandoned coal mines as underground water reservoirs is an effective idea for reducing eco-geological risks in mining districts. Accurate estimation of reservoir capacity is conducive to guiding the construction of an underground water reservoir. In this paper, estimation models of underground water storage capacity were established, which were divided into two kinds: horizontal mining district and inclined mining district. Furthermore, the minimum porosity of broken rock mass was analyzed based on laboratory experiments, and the fitted equation of minimum porosity was developed. A modern coal mine in northwest China was taken as an example, and the feasibility of the proposed model was verified by in-situ measurement. Finally, the effects of porosity of broken rock mass, water storage height and coal seam dip angle on water storage capacity were presented. The coal seam dip angle should be the principal consideration in choosing the site of an underground water reservoir. HIGHLIGHTS Underground water reservoir can realize sustainable development in mining areas.; Prediction model of underground water storage capacity was established.; The minimum void ratio of broken rock mass with different gradations was studied.; The coal seam dip angle significantly affects underground water storage capacity.;

Keywords

• broken rock mass
• minimum porosity
• modern coal mining
• storage capacity
• storage of mine water