Abstract
two roadways in adjacent working face of Baode Mine may have the risk of water inrush at the same time, so it is necessary to construct long borehole to cover the roadway excavation. On the basis of the hydrogeological conditions of the mine, the safe water insulation thickness and water inrush coefficient of coal seam No .8 are calculated. The results show that the water inrush coefficient is 0.035-0.037 MPa/m, which is less than the critical value 0.06 MPa/m and the bottom plate has no sudden water hazard. In the construction of No .10 coal seam, the directional long borehole is used to detect whether there is a hidden structure communicating with the floor limestone and to drain water. The test shows that there is no effluent phenomenon in the borehole, which proves that there is no hidden structure in No .10 coal seam.
Highlights
The directional drilling technology has developed rapidly in recent years because of its controllable drilling track, accurate measurement of drilling track and high target layer drilling rate
The rubber roadway of No .8 coal 81312 face and the auxiliary roadway of 81313 face developed by Baode Coal Mine are restricted by the existence of limestone water inrush in the bottom plate, which affects the rapid recovery of mining area
Roadway excavation is needed for mining surface, and it is urgent for construction drilling to explore the water rich condition of roadway floor limestone and cover roadway excavation
Summary
The directional drilling technology has developed rapidly in recent years because of its controllable drilling track, accurate measurement of drilling track and high target layer drilling rate. At present, it has been widely used in the fields of water exploration, gas prevention and control, floor grouting reconstruction, geological structure exploration and so on[1,2,3,4,5]. The construction of fan-shaped multi-branch directional holes in the target horizon can increase the coverage area of the borehole and better explore the geological conditions of the target horizon.[610]. The multi-branch directional drilling is used to solve the problem in the bottom plate No .10 coal, and the drilling construction of water exploration and discharge hole is carried out to ensure the safety of roadway excavation
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