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| Study on the development law of microseismic events in working face before and after hydraulic fracturing |
| Yang Bo1,2,3, Zhou Jinyan1,2,3, Wang Guoju1,2,3 |
| 1. Hebei Coal Research Institute Co., Ltd.，Xingtai 054000， China; 2. Key Laboratory of Mine Water Disaster Detection and Prevention and Control， Xingtai 054000， China; 3. Hebei Key Laboratory of Mine Microseismicity, Xingtai 054000， China |
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Abstract With the increase of mining depth and gas content in coal mine, roadway layout and surrounding rock geological conditions were becoming more and more complex. Deformation was easy to occur, and safety problems were more prominent. At this time, hydraulic fracturing and other methods could be used to cut off and weaken the suspended roof structure and reduce the stope pressure. The comparative analysis of the roadway before and after hydraulic fracturing was carried out, and the development characteristics of microseismic events in the working face were analyzed in depth. After fracturing, the activity of the roof event was enhanced, the activity of the floor was weakened, and the plane distribution was more dispersed and the distribution range was wider after fracturing. After fracturing, the fracture range of the overlying surrounding rock increased, the pressure conduction was smooth, and the pressure relief near the coal seam was obvious. The proportion of events near coal seam under the coal seam floor in 0-5 m increased by 53.5 %, the maximum disturbance depth of the floor decreased by 16.7 %, and there was no event development below Benxi limestone. Combined with microseismic data and field feedback, after fracturing, the pressure period of the working face became shorter, the step distance became smaller, the proportion of events with energy value greater than 5 000 J after fracturing decreased, and the vertical distribution changed from centralized to decentralized. The stress release in the stope was soothing, the dynamic pressure hazard was reduced, and the roadway deformation was effectively alleviated, which provided a guarantee for the safe mining of the working face.
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