Geomechanical substantiation of the parameters for coal auger mining in the protecting pillars of mine workings during thin seams development

The paper focuses on mining hard-to-reach coal reserves, concentrated in the protecting pillars of main mine workings using auger technology. One of the Western Donbass coal enterprises - Pavlohradska Mine of PJSC DTEK Pavlohradvuhillia - is selected for the research, where in the conditions of С4 seam the use of the Auger machine BShK-2DM is considered for coal extraction from protecting pillars of one of the main mine workings. The initial data have been substantiated and a geomechanical model has been constructed for numerical modelling the pillars stress state of the system “rock mass - drilled well”, with the varied width of the interwell pillar. It has been determined that the horizontal rock pressure component, which forms destructive tension stresses, is of predominant importance to substantiate the dimensions of interwell pillars. The pillar optimal width of the С4 seam eastern section behind the Pivdenno-Ternivskyш fault at a depth of 120 m may be a value not less than 0.25 m. The accepted interwell pillar width is 0.3 m. The level of coal losses during its extraction from protecting pillars of one of the main mine workings has been determined, which is in the range of 20-30%.