高位钻孔抽放最主要的影响因素是合理层位选择，其钻孔参数应根据采空区冒落带及裂隙带高度来设计。
The reasonable layer selection is the main influencing factors for gas drainage by high level borehole, the borehole parameters is based on the caving & fracture zone height of gob.
根据经验公式，计算了各部位煤洞采空区的冒落带及裂隙带高度。
According to the experiential formula, the caving-in zones and fracturing zones of the coal cave mined out area have been calculated.
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