中文摘要：

针对下行钻孔在瓦斯抽采过程中积水排出难和排水效率低的问题，提出了一种多孔并联式压风排水技术。根据两相流理论得出压风排水适用的条件及排水管在钻孔内的最大允许长度，设计了基于“压风排水”的下行钻孔封孔工艺和多孔并联式的排水系统。在余吾煤业公司S2107高抽巷的应用表明：试验钻孔瓦斯抽采浓度最高可达71％，单孔平均瓦斯抽采纯量为0．078m＾3／min，单孔平均瓦斯抽采纯量与普通抽采孔相比提高了3．39倍。该技术不仅解决了下行钻孔内积水难以排出的问题，还实现了封孔、排水和瓦斯抽采的一体化，提高了瓦斯抽采效果。

英文摘要：

To counter to the problem of difficult water removing and low water removing efficiency in gas drainage process by downward boreholes, a parallel multi-hole technology for water removing by compressed air was proposed. Based on the theory of the two-phase flow, the applicable conditions for water removing by compressed air and the maximum permissible length of water removing pipe in the borehole were obtained, the hole-sealing technology for downward boreholes based on ＂water removing by compressed air＇and the parallel muhi-hole water removing system were designed. The application of this technology in S2107 high-level gas drainage roadway in Yuwu Coal Company showed that the gas drainage concentration by the test borehole was up to 71%, and the average amount of pure gas drainage by a single hole was 0. 078 m^3/min, increased by 3.39 times as compared with that by a normal drainage hole. This technology not only solved the problem of difficult water removing in the downward boreholes, but also achieved the integration of the borehole sealing, water removing and gas drainage, and improved the effect of gas drainage.