Numerical simulation study on evolution of overlying rock fractures of extra thick coal seam mining
Coal seam mining causes damage to the overlying rock and the evolution and development of fractures.The gas released due to mining pressure relief flows and accumulates in the fracture channels,posing a serious threat to the production of the working face.The 3 DEC numerical simulation experiments were adopted,based on the mining of the B2 thick coal seam working face in Kuangou Coal Mine,the stress evolution law of the mining overlying rock was simulated and studied,and the four stage distribution characteristics of the stress evolution of the overlying rock was obtained.On the basis of characterizing the degree of fracture development using the over-burden pressure relief coefficient,the dynamic evolution process of the fracture enrichment area was plotted.And by analyzing the char-acteristics of mining overlying rock failure and fracture development,the mining induced overlying rock fractures were divided into four zones along the horizontal direction within the height range of the fractured zone,namely:compaction fractured zone,structural fractured zone,tensile fractured zone,and original fractured zone.The evolution of mining overlying rock fractures and the division of zones can provide technical reference and basis for arranging boreholes to extract gas from the goaf,thereby eliminating safety hazards and achie-ving the utilization of gas resources.
extra thick coal seam miningnumerical simulationoverlying rock failurefracture evolutionzone division
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