Study on reasonable width of coal pillar in retracement channel under goaf edge

Abstract

In order to study the reasonably reserved width of the coal pillars in the roadway for lower and middle coal seams in shallow and short distance coal seams, the research methods of theoretical analysis, similar simulation and numerical simulation were used to study the characteristics of the overburden rock structure of the coal roadways for the roadways in the lower coal seams. To determine the reasonable width of the coal pillars for the roadway under the edge of the goaf, the studies show that: after the completion of the mining seam, due to the coal pillar of the stop-mining line of the upper coal seam, the different layout positions of the retracting passage of the lower coal seam will lead to the great difference in the overburden structure of the coal pillar of the roadway, thus resulting in the different load of the coal pillar; when the width of coal pillar is set, the width of coal pillar in the goaf compaction zone should gradually decrease from the pressure relief zone to the pressure relief zone and gradually increase from the pressure relief zone to the solid coal in the upper coal seam. The width of coal pillar in the pressure relief zone should be smaller than the solid coal zone. By establishing the numerical simulation model of the retracement passage below the goaf edge under working conditions, the reasonable width of the coal pillar is determined to be 18 m.

Keywords

• close distance coal seam
• retracement channel
• protection coal pillar
• overlying rock structure
• reasonable width