Synergistic analysis of the mine pressure behavior and surface subsidence law of the 8 meter ultra-high working face in shallow coal seam

REN Jianxi; SUN Chengwei; ZHANG Jingui; HU Jian

doi:10.11799/ce202507018

Abstract：In order to study the mine pressure behavior and surface subsidence law induced by 8 meter super-high working face mining,the stress monitoring system was arranged in the No.2203 working face of Zhangjiamao Coal Mine and GNSS automatic observatory was deployed in the surface to collaboratively analyze the mine pressure behavior law and surface subsidence characteristics during the working face mining.The mine pressure behavior showed distinct regional weighting,with a pattern of"higher in the middle and lower at both ends"in the working resistance of the supports.Compared to ordinary mining heights,the large mining space and the increased load from the roof in super-high working faces result in greater pressure on the support,leading to more severe mine pressure.The periodic weighting cycles in super-high working faces are generally longer,with high weighting intensity,following a pattern of alternating large and small cycles.During weighting in the super-high working face,the support resistance increases sharply,with a significant amplitude of resistance growth.The No.2203 working face has a shorter active period of surface subsidence,and the sinking speed is bigger during the period,and the surface subsidence is violent,but the recession period is longer;The influence range of the mining-induced surface subsidence is large,but the area of significant subsidence is smaller,and the basin formed by the subsidence is in the shape of an"inverted straw hat";The surface cracks are obviously developed,with large widths,mainly above the middle of the working face goaf,distributed in a non-closed ring,and the surface of the whole working face is seriously damaged,forming obvious step-like cracks;The amount and scope of mining-induced surface subsidence above super-high working face are larger,and the subsidence is faster and lasts longer than that of the ordinary working face.The weighting in No.2203 working face happens 1-5 days before the subsidence,which is a warning of surface subsidence,and then as the periodic weighting continues to occur,the surface subsidence goes through the slow stage,rapid and stabilization stages.In the rapid subsidence stage,the working face weighting is more frequent and violent,which has more weighting number,smaller interval,and longer duration;And the faster the working face advances,the faster the surface subsides.