Coal Engineering ›› 2025, Vol. 57 ›› Issue (8): 49-56.doi: 10. 11799/ ce202508008

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  • Received:2024-08-15 Revised:2024-12-03 Online:2025-08-11 Published:2025-09-11

Abstract:

It is crucial to control the stability of the surrounding rock in thick loose layer thin bedrock roadway roof cuttings, and the static fracture cutting technology helps to reduce the impact of the cuttings on the stability of bedrock. In this paper, taking the engineering background of 16061 working face roof-cutting along the hollow stay lane in Zhaogu No. 1 Coal Mine as an engineering background, numerical simulation, indoor test and engineering practice are comprehensively used to reveal the mechanism of static fracturing slitting in the roof of the roadway in the mining area with thick loose layer and thin bedrock, and optimize the related process. The results show that: with the increase of expansion pressure, crushing occurs in the range of 75mm of the hole wall by tensile and shear damage of compressive stress, and the range of 75~110mm of the hole wall by compressive stress is converted into tensile stress, which produces tensile cracks in the rock within the range, and eventually the crushed area and cracks penetrate to form the weak surface of the fissure. With the increase of hole spacing, the tensile stress between the holes shows a quadratic curve type distribution, and the connectivity of plastic zone decreases at the same time, and the optimal fracturing hole spacing is determined to be 300mm.On this basis, the filling method of liquid static pressure grouting using static fracturing agent and the fast sealing method of hole sealing device are proposed for downhole top cutting, and the optimal water/dose ratio considering the fluidity and expandability of slurry is determined to be 0.5, and the process flow of static fracturing top-cutting and cutting operation is constructed. The process flow is constructed. The field industrial test shows that the time required for single-hole operation is less than 5 min, and obvious cracks appear on the inner wall of the drill hole, and the length of fracturing slit can reach 90% of the effective depth of drilling charge, and the effect of the slit can meet the demand of top-cutting in the current back-mining roadway. The research results can provide theoretical basis and practical reference for the fracturing and slitting project in the mining area with thick loose layer and thin bedrock.

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