Study on the mechanism of abnormal roof weighting and zoning control under multi-seam remnant coal pillars in underground working faces

GUO Qingrui; YU Bo; ZHANG Zhiqiang; CUI Hailong; LU Xiong; ZHANG Xiaochun; WU Zhidong

doi:10.11799/ce202512010

Abstract：To reveal the coupled disaster-causing mechanism of overlying goaf and remnant coal pillars on abnormal roof weighting in underlying working faces and to ensure roof stability along with safe and efficient mining,we systematically investigated the mechanism of abnormal roof weighting under multi-seam remnant coal pillars at the 32302 working face of Chahasu Coal Mine.A comprehensive methodology integrating theoretical analysis,numerical simulation,and field monitoring was employed.A floor stress zoning model under the influence of remnant coal pillars was established,clarifying the characteristics of the shallow compression-shear composite stress concentration zone in the floor and the abnormal stress distribution patterns within a 50 m range ahead of and behind the coal pillars.Based on elastic thin-plate theory,a mechanical model of periodic roof weighting in the main roof was developed,revealing the mechanical evolution of roof instability:initial destabilization occurs when the face advances to 11.4 m,with significant instability characteristics observed at 15 m of advance.Combining with three-dimensional numerical simulation and field monitoring data of hydraulic support resistance,the stress superposition features and dynamic propagation paths induced by overlying goaf edges and remnant coal pillars were identified.Results show that the maximum increase in advance stress peak reaches 34.08％,and the concentrated stress beneath remnant coal pillars reaches 24.23 MPa.Based on these findings,a three-level zoning control criterion was proposed based on face advance position,dividing the area into:a 50 m warning zone ahead of the setup entry,a 20 m high-risk zone around the setup entry,and a 20 m pressure-relief zone behind the setup entry.The findings provide a reliable theoretical basis and technical guidance for roof disaster identification and regional control in working faces under multi-seam remnant coal pillars.