Feasibility study on ascending mining of thick coal seam group at close distance in soft rock mining area

Taking the Ⅱ_2-1, Ⅱ_2-2 and Ⅱ₃ coal seams of Lingdong coal mine as the research object, using FLAC^3D finite element software to simulate, the study is conducted after mining the Ⅱ_2-1 coal seam and the roof of the Ⅱ_2-1 coal seam is completely destabilized, the excavation of the Ⅱ₃ coal seam The influence of the Ⅱ_2-2 coal seam floor and the secondary influence of the Ⅱ_2-1 coal seam on the roof of the Ⅱ_2-2 coal seam after being disturbed.The simulation results show that the mining of the Ⅱ₃ coal seam has no direct damage to the Ⅱ_2-2 coal seam, but the stress concentration areas generated by the coal pillars on both sides of the Ⅱ_2-1 coal seam and the Ⅱ₃ coal seam have a certain degree of influence on the safety production of the Ⅱ_2-2 coal seam.Finally, the ratio discriminant method and the three-zone discriminant method are used to judge the feasibility of ascending mining of the Ⅱ_2-2 coal seam.The results show that:after the Ⅱ₃ coal seam is mined, the interval between the Ⅱ₃ coal seam and the Ⅱ_2-2 coal seam can meet the requirements of the Ⅱ_2-2 coal seam ascending mining requirement, it is of great significance to ensure the safe and efficient mining of coal seam Ⅱ_2-2, and at the same time, it has effective guiding significance for the upward mining of the mining face in the future.