Prediction Reliability of Water Inrush Through the Coal Mine Floor

Inrush of Ordovician limestone karst water through the mine floor occurs frequently in the Carboniferous-Permian coalfield in northern China. A probability index method was proposed to predict water inrushes using five indices: an aquifer water-bearing index, a structural index, an aquifuge index, an aquifer water pressure index, and an underground pressure index. Expert input was used to obtain weights for these five factors. Expert evaluation and statistical probability were then used to determine weights of the subsidiary factors, allowing the calculation of a water inrush probability index (I) and a threshold water inrush value for the Feicheng coalfield of 0.65. The Dempster-Shafer evidence theory was then used to determine a 74% degree of confidence for this prediction. Finally, the method was applied to the No. 9901 working face of the Taoyang coal mine. A subsequent 1,083 m(3)/h water inrush that occurred there aligned with the statistical results.