Strong mining pressure characteristics and stability control in large height coal face under continuous extraction: A case study

In underground coal mining, the strong dynamic pressure resulting from continuous extraction frequently leads to instability accidents. A case study was conducted at Xiaobaodang No. 1 Coal Mine to address the issues, utilizing numerical simulation, microseismic (MS) monitoring, and site observation methods. The findings indicate that significant mining pressure is observed when the damage zone above the tailgate of the current working face extends through the overlying strata of the pillar towards the neighboring gob during the second mining phase. The damage zones within the overlying rock layers of the two working faces ultimately converge, resulting in significant mining pressure at the site. The safety valve opening rate is generally above 80%, indicating significant mining pressure intensity, particularly in the tailgate. MS events and active roof movement are concentrated in the tailgate and neighboring gob during the second mining phase. The plastic zone radius at No. 112204 tailgate expands from 3 m to 7 m, with MS events primarily occurring 80 m behind to 40 m ahead of the working face, necessitating the need for reinforcement support. Following the implementation of various measures, such as coordinated support using anchors and anchor rods, continuous slotting and floor breaking, along with multi-zone grouting, the integrity of the surrounding rocks is ultimately preserved. Controlling concepts considering geological and mining factors are finally discussed and recommended. The study serves as a significant reference for the prevention and control of intense mining pressure during ongoing extraction processes.