Key technologies for prevention and control of roof water disaster at sources in deep Jurassic seams

A series of problems,such as the large amount of water inflow,the coal-water mixing problems after mining, and unsafe heading and mining due to the close distance between upper seam and strong aquifer,exist in the deep mining areas of Shaanxi-Inner Mongolia,China. To solve these problems,this study puts forward the key technologies for prevention and control of roof water disaster at sources in deep Jurassic seams. The spatial distribution in both the plane and section of aquifers (aquicludes) and water abundance distribution of aquifers are analyzed by employing the law of groundwater controlled by geological sedimentary. On this basis,in view of the characteristics of large coal seam thickness variation and the interaction of roof aquifers and aquicludes,a zoning evaluation method of water-inrush risk in accordance with the hydrogeological characteristics of deep Jurassic mine is proposed by constructing an evaluation index system composed of sedimentary environmental impact index,sandstone thickness,core recovery,unit inflow, permeability coefficient and the height of water flowing fractured zone. Then,according to the water prevention and control proposal of “intercepting from the source,centralized drainage,source prevention and advanced governance”, four regional closure optimization models composed of upward mining and low flow closure,working face unilateral clo-sure,working face bilateral closure and working face direction adjustment closure mode are determined. Finally,a case study at Mengkeqing Mine and Muduchaideng Mine in Shaanxi-Inner Mongolia mining area is carried out. The applica-tion results show that:① The sandstone aquifer in the Member 1 of Zhiluo Formation is mainly channel sediments,and the sand body has good spatial continuity,which is the main water-filled aquifer in the deep Jurassic mine. ② The dangerous water-inrush areas of the No. 3-1 coal roof aquifer are mainly distributed in the south of the first mining are-as in Mengkeqing Mine,showing an east-west strip pattern,which is consistent with the actual situation. ③ According to the evaluation results of water-inrush risk in the first mining areas of Menkeqing Mine,two modes composed of work-ing face unilateral closure,upward mining and low flow closure are applied,and the application effects in practical pro-jects are analyzed. System establishment of source prevention and control technologies will still be the key research di-rection in deep Jurassic mines.