Study on Overall Pressure Relief Mining Without Pillar in Protective Layer Through UDEC Numerical Simulation Experiment

In view of the problem that the low permeability and high outburst coal seam group does not have the mining condition for the protection layer of conventional coal seam (coal thickness ≥0.8 m) and the ability to eliminate the blind area of pressure relief in the protected layer under the residual coal pillar, the overall pressure relief mining technology without coal pillar in the semi-coal rock protective layer of the extremely thin coal seam was proposed. Based on the geological conditions of Shaqu Coal Mine, it’s concluded by the use of UDEC numerical simulation analysis that with the increase of the width of the coal pillar of the protective layer, the width of the unloading blind zone of the protected coal seam roughly conforms to the linear growth law of the fitted linear equation y=17.09x-10.05, and the fitting degree R²=0.896 8. When there is no pillar mining, vertical stress concentration does not occur in the protected layer below the original pillar position, that is, the blind area of unloading pressure is eliminated.