突出煤层密集钻孔瓦斯预抽的数值试验

Numerical Test of Gas Pre-drainage with Dense Boreholes in Outburst Coal Seam

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。

The dense borehole pre - drainage technology is a preventive measure for coal and gas outburst. In order to enhance the pre - drainage efficiency and rationally arrange borehole, the solid - gas coupled RFPA2D - GAS numerical test system is applied to study the variation regularity in gas pressure and drainage radius under different factors. These factors include coal seam permeability coeffi- cient, space between boreholes, borehole diameter, gas content coefficient and pre -drainage time. It can be concluded that if large permeability coefficient and large borehole diameter are used with small space between boreholes and small content coefficient in the coal seam, then the lowered range in gas pressure and drainage radius will be large. It is required the shortest pre - drainage time to a- void the outburst danger of coal seam. If the pre - drainage time prolongs, the lowered range in gas pressure and drainage radius in- crease. An engineering practical experiment is found to approve to this numerical test.