Mine pressure behavior in shallow coal seam mining under room-and-pillar goaf in gully terrain

DENG Yupei; HU Baiyu; CUI Bo; JIANG Dapeng; ZHANG Kunming; PAN Weidong

doi:10.11799/ce202601012

Abstract：In the Shenfu Mining Area,the surface is crisscrossed by gullies with large elevation differences.Under the combined action of mining disturbance and surface topography,the laws of mine pressure behavior are complex when the working face advances beneath gully areas.Additionally,the upper coal seam was mined using the room-and-pillar method,and the remnant coal pillars affect the roof stability during the lower seam extraction.To address this issue,taking the 51208 working face of Guojiawan Coal Mine as the engineering background,theoretical analysis,numerical simulation,and field monitoring was combined to investigate the mine pressure behavior laws when mining under room-and-pillar goaf in gully terrain.The results show that:The stress of room-and-pillar coal pillars in gully areas increases toward the extension segment of the slope crest,with the maximum influence position shifting to the middle of the slope,exhibiting the characteristics of"increasing on the slope,decreasing at the slope bottom,stepped distribution,and centripetal offset".Gully terrain dominates the mine pressure behavior of the lower working face,with the difference in roof stress between the working face mined under room-and-pillar goaf being only 1%.The patterns observed in the on-site monitoring of mine pressure are similar to the simulated stress characteristics.The periodic weighting interval in the bottom of the slope area is approximately 7.45 m,while the periodic weighting interval in the uphill section is 9.54～11.74 m.The average periodic weighting interval at the top of the slope and in the stable mining section is 10.0 m.Overall,the mine pressure shows zonal characteristics of"short and small at the slope bottom,chaotic and large in the middle slope,stable and widespread at the slope crest"and a behavior law of"unilateral concentration in the early stage,asynchronous fluctuation in the middle stage,and global stability in the later stage".