Risk Evaluation of Water Inrush in Poor Water Yield Capacity Aquifer of Coal Seam Direct Roof

For the difficult problem of water inrush evaluation of coal seam roof, when the water yield property of the coal seam roof aquifer is weak and the water-resisting layer between the coal seam and the aquifer is lost. Based on the principle of three maps method, water yield property of aquifer is evaluated and the partition map for water yield capacity is drawn by the method of water-rich index based on multi-source information fusion. The ratio of the distance from the fractured zone to the aquifer and the aquifer thickness is the index to determine cracking degree of partition map; compositely overlaying water-rich zoning map and the fracturing degree zoning map, according to the evaluation criteria of water bursting risk, the evaluation results of the water bursting risk of coal seam roof were obtained. The results show that the method can reflect the influence of the crack height on the water inrush risk, and is in good agreement with the actual situation. It is more scientific and effective than the traditional three maps method.