Technology of Regional Advance Water Prevention and Control Applied to Pressurized Coal Mining Zone Above Ordovician Limestone Karst Water

According to the seam mining threatened by pressurized Ordovician limestone karst water and the water keeping mining status on Han-Xing Mining Are a, a regional advance water prevention and control technology was provided based on the advance and initiative, regional control, full reconstruction and pressurized m ining as the guidance principle.The technology was applied to the reconstruction of the regional advance grouting at the top layer of an Ordovician limestone water aqui fer in Han-Xing Mining Area. The final pressure at the borehole top was 1.0 MPa and would be kept over 30 min and a grout adsorption of a borehole was less than 50 L/min.Those above conditions would be the standard to terminate the grouting operation.In the experiment process, key technologies of surface multi branch horizontal drilling were applied.Finally, the target to reinforce the aquifer in the floor of the seam and to reconstruct the aquifer at the top of the Ordovician limestone was realized. The possibility to have a water inrush from the seam floor would be highly reduced and the coal resources threatened by the pressured water could be safety mined.