Research on the Extraction Technology of Gas-Integrated Working-Face in Close Coal Seam Mining in Permafrost Area

Abstract

In order to understand the mechanical deformation characteristics of the permafrost layer and the stress-fracture-gas seepage law of the superimposed mining of the proximity coal seam group, a coupled gas-solid model of the proximity coal seam in the permafrost area was constructed based on the theoretical model of small deflection of thin plate and the deformation control equation, gas transport equation, porosity evolution equation and permeability evolution equation of the coal rock body, and the analysis of the dependent project. The analysis was carried out at the NMT coal mine. The results show that the multiyear permafrost seam in the NMT coal mine has a tendency to move to the left and will produce extensive pull damage near the right end. The initial and periodic collapse steps are 192.87 m and 43.24 m, respectively; the pore and fissure structural characteristics of the NMT coal seam are not conducive to gas transport, and the stress and fissure fields have a nonlinear increasing effect. The study also proposed the “protected seam mining and bottom extraction lane directional drilling group comining technology” to increase the daily production of working face by 25.8%. The results of the study can be used as a reference for similar projects.