Research on reasonable width of coal pillars for protecting roadways in irregular island fully-mechanized caving face

Li Ning; Bi Zhiqiang; Zhao Yanfang

doi:10.19896/j.cnki.mtkj.2025.05.011

Abstract：Based on the limit equilibrium theory,the development width of the fractured zone of the mining coal pillar in the irregular i-solated fully-mechanized caving working face of Dashuitou Coal Mine Branch was analyzed,and a FLAC3D numerical calculation model was established to explore the distribution characteristics of lateral support pressure in goaf.The influence of different protection coal pillar widths on the movement deformation and crack development characteristics of mining roadway was studied,and the deformation of roadway during the mining period of irregular isolated working face was measured.Research has shown that the width of coal pillar crushing zone in working face of Dashuitou Coal Mine Branch is 3.78 meters.The side abutment pressure of working face shows a stress-relaxed area,a stress-concentrated area,and an original rock stress zone starting from the wall.The width of stress-relaxed area is 14 meters.It is preliminarily determined that the width of coal pillar reserved in the mining roadway of working face is 3.8 to 9.0 meters.When the width of coal pillar is small,due to the influence of side abutment pressure,the cracks in the coal pillar develop and the bear-ing capacity is poor;as the width of coal pillar increases,its bearing capacity significantly improves;but when its width is 7 meters,there is a significant stress concentration area inside the coal pillar,and due to the high stress,the plastic zone inside the coal pillar is con-nected to the lateral goaf.Based on the deformation characteristics of different coal pillar widths in the goaf on both sides,the optimal width of the protective coal pillar is determined to be 6 meters.During the actual mining period of working face,the maximum movement of roof and floor of the mining roadway is 269 mm,and the movement of two sides is 270 mm.The convergence rate of the roadway is small,and the width of coal pillar is reasonable.