采空区高位钻孔瓦斯抽放的数值模拟

依据Darcy定律,在Navier-Stocks方程的基础上,对祁南煤矿综采工作面采空区瓦斯抽放问题作了计算分析,并进行了CFD数值模拟.从理论上模拟采空区瓦斯聚集过程,直观展示了瓦斯抽采时采空区流态、瓦斯分布变化.把抽放钻孔布置在顶板裂隙内,结合上隅角埋管实施瓦斯抽放,该抽放瓦斯技术起到了对开采工作面上隅角瓦斯的截流作用,现场管路测量显示,可抽出高浓度瓦斯达30%～80%(体积分数),工作面回风瓦斯的体积分数基本控制在0.3%以下.

Numerical simulation of gas drainage with high position boreholes in goaf

Gas distribution and flowing in Qinan Mine were calculated and analyzed by means of the Navier-Stocks formula based on the Darcy law and then the method of CFD numerical simulation was used to visually display the result.The gas collection course in the falling porous media at the upper corner of goaf was simulated theoretically, which clearly illustrated the gas movement and flow pattern in goaf when the gas was drained.Based on the simulation result, the gas was drained through high-position boreholes placed in the fracture area in Qinan Mine, and it was proved to prevent the gas from flowing to the upper corner.As a result, piping measurements show, the gas concentration in the drainage pipeline reached to about 30% to 80% and the gas concentration of return air was lowered to as low as 0.3%.