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密集钻孔预抽瓦斯技术是一种防止煤与瓦斯突出的措施,为了提高预抽效率和合理布置钻孔,应用固气耦合RFPA2D-GAS数值试验系统,研究在不同煤层透气系数、钻孔间距、钻孔直径、煤层瓦斯含量系数和预抽时间等因素条件下,煤层瓦斯压力和抽采半径的变化规律。得出透气系数、钻孔直径越大,钻孔间距和瓦斯含量系数越小,煤层瓦斯压力下降幅度越大,抽采半径越大,达到消除煤层突出危险的瓦斯压力值所需的预抽时间越短;随着钻孔预抽时间的延长,瓦斯压力下降范围将扩大,抽采半径增加。并用工程实例进行了验证。
In order to improve the pre-pumping efficiency and to arrange the borehole reasonably, the solid-gas coupling RFPA2D-GAS numerical test system was applied to study the gas permeability coefficient, the hole spacing , Borehole diameter, coal seam gas content coefficient and pre-pumping time and other factors, coal seam gas pressure and pumping radius changes. The ventilation coefficient is obtained. The larger the diameter of the borehole is, the smaller the spacing of the borehole and the coefficient of gas content are. The larger the pressure drop of the coal seam is, the larger the radius of gas drainage is and the pre-pumping time required to eliminate the outburst dangerous gas pressure of the coal seam The shorter the borehole pre-pumping time, the lower the pressure range of gas will be, and the radius of pumping will increase. And verified with the engineering example.