Field drilling analysis of multi-Index detection for coal pillar core zone width in deep holes

LI Dong; DING Wei; JI Yonghu; GENG Xuesheng; WANG Tao; WANG Yong; WANG Weibin; ZHAO Xianzhong; WANG Ning

doi:10.19956/j.cnki.ncist.2026.01.023

Abstract：Based on a case study of a coal mine in Shandong,this paper investigates the determination of the e-lastic core width in large coal pillars located in strongly bump-prone mines at depths approaching 1,000 me-ters.Through field tests,the following conclusions are drawn:(1)Using high-power auto-rod-add drilling rigs on site,the degree of stress concentration in the coal pillar area as well as the distribution of elastic zone,plastic zone,and fractured zone were determined based on macroscopic manifestations during drilling,including drilling cuttings particle size,quantity and intensity of coal bursts,and drill jamming incidents.These observa-tions provide a basis for selecting the relief depth of large-diameter boreholes.(2)An analysis of the drilling process indicates that the range of 0-15 meters from both sides of the roadway is predominantly composed of fractured and plastic zones,while a 50-meter central section of the coal pillar constitutes the elastic core zone.(3)The 0-15 meter zones on both sides of the coal pillar are characterized as low-stress areas with limited energy accumulation capacity,exhibiting fewer coal bursts of lower intensity;whereas the central 50-meter sec-tion demonstrates high stress concentration,significant energy storage potential,and frequent coal bursts of greater intensity.(4)Pressure relief boreholes must extend beyond 30 meters in depth,with particular empha-sis on implementing intensive cuttings discharge in the section exceeding 15 meters.This process actively transfers stress from the panel-side elastic core toward the goaf area,effectively mitigating rockburst risks dur-ing subsequent mining of adjacent panels.