Zonal evolution characteristics of overlying strata and mining thickness effect based on integrated identification of fracture field and seepage field
KONG Xiangguo
ZHANG Hui
LI Shugang
LIN Haifei
ZHAO Pengxiang
ZHAO Hongchao
LI Ke
WANG Cuixia
ZHAO Tianshuo
JI Pengfei
HE Di
Abstract：Clarifying the flow and accumulation patterns of pressure-relief gas in goafs is essential for ensuring mine safety.In this study,based on a working face in the Binchang mining area,the in-fluence of varying mining heights on overlying strata fractures and gas migration was investigated through numerical simulations,which was verified by gas drainage data at field.The results demon-strate a positive correlation between mining height and the extent of fracture development in overly-ing strata.As mining height increased,the rotational space for overlying strata expanded,thereby promoting fracture generation,with significant increases in fracture density,separation volume,fractal dimension,and connectivity coefficient.Greater mining heights leaded to expanding of pres-sure-relief gas migration range,with a more pronounced effect on gas mobility in the middle and up-per zones.Based on the characteristics of fracture evolution and gas flow,the distribution of pres-sure-relief gas in mining-disturbed overlying strata was classified into three distinct zones:the lower diffusion zone,the middle ascending zone,and the upper advection zone.A identifying criterion-in-tegrated approach between the fracture field and seepage field was established using threshold val-ues of fracture density,separation volume,fractal dimension,connectivity coefficient,and gas en-richment rate for each zone.The result shows that as mining height increased from 5 m to 15 m,the spatial extent of gas migration zones expanded by an average of 112.6％.Among them,the promotion effect of mining height on middle ascending zone and upper advection zone is much greater than that of lower diffusion zone.The gas drainage effects of directional drilling in the test working face were good with pure gas flow rate of 0-14.43 m3/min.Drainage efficiency across zones follows the order:middle zone＞lower zone＞upper zone.And the ratio of drainage vol-ume of pressure-relief gas about this drilling site to the absolute gas emission of the working face presented stepped growth characteristic.These findings verified the feasibility of proposed zonal classification method and the rationality of borehole layout,offering theoretical support for optimiz-ing gas drainage strategies.
Keywords：overburden stratapressure-relief gasfracture fieldseepage fielddirectional bore-holesgas control
Publication Date：2026-01-30
Online Publishing Date：2026-01-28(First online date of this platform, not the publication date of the document)
Pages：16( 164-179 )