Research on precise grouting to prevent water disaster technology inHuanghebei Coalfield

In order to solve the water disaster of limestone in the north of Huanghe coalfield,the authors take the directional drilling grouting to control the water inrush of No.11 coal seam in Qiuji coal mine as an example. Firstly, the water abundance of roof and floor limestone were analyzed, combining with the results of transient electromagnetic and pumping tests; then, the precise grouting technology, involving the drilling modes of plum blossoms and upper and lower strata pentration, and the real-time monitoring of hydrological observation boreholes was brought up based on the idea of controlling territorial water inrush in advance and integration treatment of water source and channel, and the characteristics of inhomogeneous water abundance; at last, a total of six main drillings including 25 branch holes were constructed with 12 011 m of drilling footage and 104 880 tons of grout amount. The results showed that after precise grouting to control grout diffusion, the water abundance region of No.4 and No.5 limestone as the roof of No.11coal seam almost disappears, and the permeability coefficient of roof aquifer decreases to 0.010 4 m/d, meanwhile, the water flow of observation boreholes drops to less than 5 m3/h from 40～260 m3/h before grouting, realizing the safe tunneling of blind incline shaft to sucessfully disclose the No.11 coal seam, and providing the safety guarantee and guidance for 60 million tons of coal reserves. The precise grouting technology to drillinng modes of plum blossoms and upper and lower strata pentration, and the real-time monitoring of hydrological observation borehole could effectively fill the cracks and covert water channels of limestone aquifer, and accurately control the range of slurry diffusion, which provide the scientific gudance to the similar coalfield encounted.