Coal Engineering ›› 2024, Vol. 56 ›› Issue (1): 113-118.doi: 10.11799/ce202401017

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Research on the development law of fractures in overlying strata of coal seams in close distance and upward mining

  

  • Received:2023-02-20 Revised:2023-06-28 Online:2024-01-20 Published:2024-01-29

Abstract: In view of the technical problem that the upward mining of overlying rock movement may destroy the integrity of the upper coal seam and easily cause the upper coal seam to be unable to be mined,Based on the engineering background of the influence of the mining of 9 coal face on the mining of the overlying 5 coal seam in a certain mine, this paper uses the methods of theoretical analysis, numerical simulation and physical simulation to study the damage of the overlying rock of the upper strata after the mining of the coal seam in a short distance, the development law of the rock fissure and the law of the mining pressure of the working face.The results are as follows:①The range of the plastic zone of the upper strata after the mining of the 9 coal seams under the close coal seam is analyzed theoretically, and the average height of the collapse zone is 9 m and the height of the water-conducting fracture zone is 36 m according to the three-zone discrimination method; Kobtained by ratio analysis method is 19.99, which is greater than 7.5 for medium hard rock stratum; The interval obtained by the surrounding rock balance method is 45m, which is far less than the interval between Coal Seam 5 and Coal Seam 9;②The numerical simulation shows that the overlying 5 coal seams of the 9 coal seam working face under the close coal seam are located in the plastic area formed after the mining of the lower coal seam, and there will be no stress concentration in the area where the protective coal pillar is left;③The physical simulation shows that the maximum subsidence value of coal seam 5 is 10 mm and the height of the model collapse zone is about 15 cm after the mining of coal seam 9 in close proximity, which conforms to the development law of mine pressure and overburden movement. Relevant research results demonstrate the feasibility of upward mining of the overlying 5 coal seam after the mining of the 9 coal seam in close distance.