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为了研究本煤层瓦斯抽采钻孔周围有效半径的分布规律,运用钻孔周围煤层瓦斯流动的连续性方程、理想气体状态方程、气体运动方程和瓦斯含量方程,建立本煤层顺层钻孔周围瓦斯压力分布规律数学模型。在煤层施工瓦斯抽采钻孔,现场测定不同钻孔深度的抽采负压,分析孔深和抽采负压的数学关系。最后建立钻孔周围瓦斯压力沿孔深的变化关系式,研究瓦斯抽采钻孔周围有效抽采半径的分布规律。发现抽采负压随着孔深的增加呈线性递减,钻孔有效抽采半径随着孔深的增加也呈现出递减的趋势。
In order to study the distribution rule of the effective radius around the gas drainage borehole in this coal seam, the continuity equation of gas flow around coal seam, ideal gas state equation, gas equation of motion and gas content equation are established to establish the gas Pressure distribution law mathematical model In coal seam gas drainage drilling, on-site determination of different drilling depth extraction negative pressure, analysis of deep hole and extraction negative pressure mathematical relationship. Finally, the relationship between the gas pressure around the borehole and the depth of the hole is established to study the distribution of the effective drainage radius around the gas drainage borehole. It is found that the suction pressure decreases linearly with the increase of hole depth, and the effective drilling radius decreases with the increase of hole depth.