通过对水平钻孔布置在煤层顶板不同高度时的抽采效果进行研究可为采空区瓦斯抽采时的水平钻孔布置高度选择提供理论依据.利用Fluent软件对钻孔与煤层不同距离时的钻孔抽采纯量与抽采混量、采空区瓦斯分布、上隅角瓦斯浓度变化进行数值模拟,并且研究了钻孔抽采纯量与抽采混量、采空区瓦斯分布、上隅角瓦斯浓度变化与钻孔布置高度的关系.研究结果表明:随着钻孔与煤层之间的距离增大,钻孔的抽采瓦斯纯量基本逐渐增加,抽采混量呈现减小趋势,抽采瓦斯浓度逐渐增大;采空区内部瓦斯浓度靠近进风巷侧和采空区深部逐渐降低,靠近回风巷侧呈现先减小再增加再减小规律,竖直方向上在顶、底板附近瓦斯浓度逐渐降低;上隅角瓦斯浓度先减小再增加再减小最后趋于平衡.
When horizontal boreholes in coal seam roof are arranged in different height,through studying their drainage effect,a theoretical basis for the selection of horizontal boreholes ' arranged height can be provided,which are used for gas drainage in goaf. Drainage scalar quantity and mixing quantity,gas distribution in goaf and gas consistency change in upper corner under the condition of different arranged distance between borehole and coal seam are numerical simulated by Fluent,and the relation between these and boreholes arranged height are studied. The research results show that with the distance between borehole and coal seam enlarges,the drainage scalar quantity basically gradually increases. Drainage mixing quantity shows a decreasing trend,and drainage gas consistency gradually increases. Close to the side of intake airway and in deep goaf,gas concentration internal goaf gradually decreases,while it is close to the side of air- return way,it shows a trend of first decreasing and then increasing and then decreasing,in vertical direction near the roof and floor,gas concentration gradually decreases. Gas concentration in upper corner first decreases,then increases and then decreases,and finally gets balanced.