To explore the impact of thick and hard main roof of longwall coal mining on the settlement of overly-ing strata and a new low-damage mining methods,numerical simulations and physical simulations were conduct-ed.Both physical simulation and numerical simulation results show that the mining-induced bulking coefficient of immediate roof is significantly greater than that of main roof.Based on simulation of the characteristics of min-ing-induced strata movement,a calculation model for descrbling the settlement of the overburden induced by coal mining was developed.Based on the characteristic that the bulking coefficient of immediate roof significantly greater than that of hard basic roof,a new low-damage mining method for controlling the failure of the overbur-den is proposed by pre-fracturing the thick and hard basic roof using hydraulic fracturing before coal mining.The method uses hydraulic fracturing to weaken and fracture the thick and hard basic roof,which is further damaged by abutment pressure,causing it to collapse and scatter randomly in the goaf.The proposed method increases the mining-induced expansion of the hard roof and utilizes its self-expansion to fill the goaf,reducing the space for overburden to sink.Numerical simulations confirmed the effectiveness of this method in regulating the mining-induced deformation of the hard roof and reducing the sinking of overburden.This method provides guidance for green and efficient mining in coal mines.
low-damage miningcoal mine ground controlhydraulic fracturingregulation of overburden struc-turebulking coefficient of overburden
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