尺寸效应影响的抽采孔周煤体分区渗透特征OA

To elucidate the influence of gas channel permeability resistance around dual-prevention boreholes in coal mines with compound disasters of coal and gas outbursts and rock bursts,triaxial permeability tests were conducted on single-graded and composite specimens with varying heights.Analyzing the relationship between permeability and specimen height,revealed the size effect of permeability.The head loss along the flow path model was introduced to characterize permeability considering the frictional head loss along the flow path(CFR).The zonal permeability characteristics within the influence area of dual-prevention boreholes were clarified.The results indicate that the primary mechanism behind the permeability size effect is the intensification of inertial effects with increasing seepage channel length.Permeability characterized by the CFR,which accounts for this inertial effect,can be used to identify dominant gas migration pathways.The study confirms that coal mass size is a key factor influencing affecting permeability capacity,providing a theoretical basis for optimizing borehole layout and enhancing gas extraction efficiency.