尾巷超大直径管路横接采空区密闭抽采技术

针对高瓦斯低透近距离煤层群开采条件下“U+L”型通风系统上隅角和尾巷瓦斯浓度严重超限的治理难题，基于试验区综采工作面瓦斯涌出特征和“U+L”型通风系统瓦斯尾巷的优点及其局限性，提出尾巷超大直径管路(1 200 mm)横接采空区密闭抽采技术，并阐述了其控制采空区瓦斯渗流场的抽采原理。依据采空区瓦斯大气混合气体渗流的控制方程，建立了采空区三维渗流的CFD模型，分析得出上隅角瓦斯浓度、采空区渗流场与抽采位置距工作面距离的关系，确定了密闭抽采技术的关键参数。现场实践表明，尾巷超大直径管路横接采空区密闭抽采技术治理瓦斯效果显著，上隅角瓦斯浓度稳定在0.9%以下，尾巷瓦斯浓度从6.0%降低到1.7%以下，实现了复杂瓦斯地质条件下的安全高效开采。

Closed gas drainage technique by extra large diameter pipeline connected with goaf transversely in tailing roadway

The problem of gas concentration often seriously beyond the allowed level in upper corner of coal face and tail roadway existed when mining the soft coal seams with highly gas content and low permeability.Based on gas emission characters of fully mechanized coal face in test area and both advantages and limitations of gas tail roadway in “U+L” type ventilation system，closed gas drainage technique by extra large diameter pipeline connected with goaf transversely in tailing road way was put forward，besides，the gas drainage principle of controlling seepage field of gas in goaf was described.CFD model of three dimensional seepage in gob was established according to the governing equation of gas mixture in goaf，and through studying the CFD model， obtained the relation between gas concentration in upper corner，seepage field in goaf and the distance from coal face to gas drainage location，then the key parameters of gas drainage technique were determined.The experimental results show that this technique is very effective to control coal gas and not only keeping gas concentration less than 0.9% in upper corner，but also decreasing gas concentration from 6.0% to less than 1.7% in tailing roadway，thereby the safe and high efficient exploitation of coal is achieved under complex gas geological conditions.