Abstract
To safely and economically eliminate the threat of high geostress in the coal mining process, based on the engineering case study of pressure relief by slotting residual coal pillars at a mine in the Kailuan mining area, a method of pressure relief by slotting coal seams with a wire saw was explored, and numerical simulation was carried out. The results show that the wire saw can cut coal seams in a large area, with a cutting efficiency and slotting depth greater than those of hydraulic slotting; a stress concentration zone forms in front of the wire saw coal cutting working face and a stress reduction zone and a stress recovery zone form behind. The pressure relief range varies, increasing at first and then decreasing. The exploration and practice of pressure relief by slotting coal seams with a diamond wire provides theoretical guidance and practical reference for pressure relief by slotting coal seams.
Highlights
High geostress during coal mining is a great threat to coal mine production safety, and slotting pressure relief is an effective method to release high geostress in coal seams [1,2,3,4]
To explore a safe and economical method for relieve the pressure of the residual coal pillars and reduce and eliminate the threat of high geostress, the Hunan University of Science and Technology and Kailuan Group jointly developed a set of equipment for slotting coal seams with a wire saw and carried out a pressure relief by cutting coal pillars with a single wire between the T3150 air channel and T2051 North driving roadway No 2
In the practice of slotting coal seams with wire saws, a 30 m slotting depth cut by a single wire has been realized
Summary
High geostress during coal mining is a great threat to coal mine production safety, and slotting pressure relief is an effective method to release high geostress in coal seams [1,2,3,4]. When coal rocks with a firmness coefficient f of 0.3∼1 are cut under these conditions, an annular slot with the slot height of 2∼6 cm and the slot depth of 1.5∼2.5 m can be obtained [8]. Due to the limited influence range of hydraulic slotting, to realize large-area pressure relief by slotting coal seams, it is often necessary to drill multiple boreholes and cut multiple intermittent slots in the coal seams to carry out joint pressure relief, which requires a great deal of manpower and is very costly. To find a safe and economical method for large-area coal seam slotting, a diamond wire saw (DWS) is used to replace the high-pressure water jet to cut coal seams for pressure relief. A method of slotting coal seams with a wire saw is proposed. Rough numerical simulation and the practice of pressure relief by cutting coal pillars with a wire saw, the changes in the vertical stress of coal rocks and the range of pressure relief during the advancing process of the working face with wire saw coal cutting are studied, aiming to provide theoretical guidance for pressure relief by slotting coal seams with a wire saw
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