6.Research on optimal width of section coal pillars under hard roof conditions

Abstract:

In response to the insufficient research on optimizing the width of coal pillars in the hard roof of the Wuhua No.1 Mine, numerical simulation was employed to optimize the coal pillar width parameters. This method provides 20% higher accuracy and greater convenience compared to the traditional limit equilibrium method. By analyzing the failure pattern of surrounding rock for coal pillars with widths ranging from 6 to 11 meters, it was found that when the coal pillar width exceeds 10 meters, 13% localized elastic zone forms at the top, creating an effective bearing structure that inhibits plastic diffusion. The vertical stress concentration coefficient stabilizes at 4.5, and the peak stress migrates to deeper layers, indicating the formation of an effective self-stabilizing mechanism for the coal pillar. The deformation of the surrounding rock is asymmetrically distributed, with the roof showing more deformation than the floor, and the coal rib experiencing more deformation than the coal body. In the 16201 working face of the Wuhua No.1 Mine, when the coal pillar width is 10 meters, the maximum roof subsidence is 0.12 meters, which is 29.4% reduction compared to the maximum roof subsidence of 0.17 meters for an 8-meter coal pillar in the hard roof condition at the Shenan'ao coal mine.

Keywords: hard roof;sectional coal pillar;surrounding rock deformation;numerical simulation