Multiple synergistic control technology of rock burst disasters in deep hard roof working faces
A significant amount of roof overhang can be formed behind the deep hard roof working faces.This can result in a high degree of strain energy accumulation and fast release speed,which can induce roof dynamic load and rock burst disasters.To achieve effectively control of rock burst disasters in the hard roof working face,taking the 1123 longwall panel of Gucheng coal mine as the background,theoretical analysis,physical simulation and on-site measurement are used to study the influence of the backfilling ratio on the movement model of the hard roof,and to propose the multiple synergetic control technology.At the primary mining stage,the backfilling ratio is less than 80％,the concentration of the mining stress in the fault-influenced area is high,and the thick top coal and hard roof exhibit local dynamic damage,which becomes a significant risk of inducing rock burst.The subsidence movement model of the hard roof under the backfilling body supporting is established,and the length of the insufficiently compacted zone and the maximum tensile stress inside the hard roof show a logarithmic decreasing tendency with the increase of the backfilling ratio.The subsidence model shows that the backfilling ratio reaches up to 90％,so that the movement mode of the hard roof is changed from periodic breaking to continuous subsidence.The proposed secondary high-pressure grouting technology reduces the volume of thick top coal expansion and sinking by 5％after grouting.Additionally,the backfilling ratio of the gob area is increased to over 90％.The microseismic monitoring and physical simulation results indicate that a high backfilling ratio prevented the hard roof from breaking.This prevented strong dynamic loading of the stope and rock burst of roof fracture type caused by the release of strain energy.To prevent coal body compression-type rock burst caused by hard roof subsidence,pre-splitting blasting of the hard roof and large-diameter drilling pressure relief measures are proposed based on filling the gob area and thick top coal grouting measures,forming the"four-in-one"multiple synergistic control technology for rock burst disaster.The large-scale blasting fracture in front of the working face released energy,resulting in an increased proportion of low energy microseismic events on the roof to 64.7％.The backfilling body was loaded quickly,reducing the degree of mining stress concentration.The hard roof subsided slowly,and the phenomenon of rapid increase in resistance of the hydraulic support disappeared.The use of synergistic prevention and control technology has successfully reduced the load and impact on the deep and hard roof working face,and reduced the risk of strong dynamic load and rock burst disaster of the 1123 longwall panel.
mining engineeringrockburstbackfilling mininghardroofbackfilling ratiosynergistic control
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