Migration failure characteristics and stress field evolution of overburden under strong mining in extra-thick coal seams

ZHANG Heng; ZHANG Junlin; JI Tianwu; ZHANG Hongkai

doi:10.11799/ce202512017

Abstract：To understand the overburden failure characteristics and fracture development patterns during the mining of extra-thick coal seams,and to further prevent safety incidents such as roof collapse and water inrush to guide production practices,this study focuses on a shallow-buried extra-thick working face in the 6-upper coal seam of Huangyuchuan Coal Mine.Using an integrated approach that includes theoretical analysis,numerical simulation,and field measurement,a comparative analysis was conducted on the displacement field,stress field,and fracture field of the mining-disturbed overburden.The results show that the overburden failure range of the extra-thick working face is approximately 150 m,with the initial caving span of the main roof being 44.74 m and the periodic caving span being 18.27 m.The failure profile of the overburden under strong mining conditions exhibits an"inverted funnel"shape,and fracture development displays distinct zonal expansion characteristics,which can be divided into:separation zone,fracture development zone,fracture closure zone,and stable zone.Mining-induced stress transmission in the overburden presents a saddle-shaped distribution,with stress concentration primarily occurring along the goaf boundary and in the central compaction zone.After the working face advances 180 m,the mining influence stabilizes into a periodic weighting phase,stress transmission upward attenuates,and mining-induced fractures are suppressed.The findings offer valuable insights for predicting overburden movement and failure height and for hazard prevention under strong mining conditions in shallow-buried extra-thick coal seams.