Research on reasonable width of section coal pillar in extra-thick coal seam and optimization of roadway support

The reasonable width is the key to the safe and efficient mining of coal pillar in extra thick coal seam.The reasonable reserve width of the section coal pillar is studied with the top-coal caving face of the extra-thick coal seam of the Hanjiawa coal mine as the object, in order to improve the resource recovery rate.Through field observation and investigation, the deformation characteristics and mechanism of the tunnel under the original support solution are revealed.The reasonable width of the section coal pillar is calculated using the stable central zone theory and the limit equilibrium theory.Three section coal pillar width solutions are designed using the FLAC^3D software.Comprehensive comparison analysis of the numerical simulation from the perspective of stress evolution and plastic zone expansion, and the optimized reasonable size of the section coal pillar is therefore determined to be 12 m.Considering the geological and production condition of the 22401 working face, through the engineering analogy method, the joint support technology of asymmetrical “anchor rod+steel belt+steel bar belt+anchor cable” is adopted to meet the primary economic requirement of improving the coal resource recovery rate, realize the engineering connotation of controlling surrounding rock deformation, displacement and crack development and reach the main technological target of proactively maintain the integrity of the surrounding rock.The study results can provide reference for section coal pillar settings of similar coal mines.