在报告中指出,采用高效率综合采煤机组和用后退式采煤法时,采用过去的瓦斯抽放方法和系统,已不能保证沼气浓度降规定的指标。因此,由于瓦斯抽放法与特殊的采矿工艺没有关系,所以很需要建立新的高效的抽放瓦斯方法。有效的方法之一就是从地面打一个定向垂直钻孔,并使其与邻近层及采空区中的水平钻孔相连通,抽放邻近 In the report, it is pointed out that the past gas drainage methods and systems have not been able to guarantee the required index of biogas concentration reduction when adopting the high-efficiency integrated coal-mining unit and the backward coal mining method. Therefore, it is very necessary to establish a new and efficient method of gas drainage due to the fact that the gas drainage method is not related to a special mining process. One effective method is to place a directional vertical borehole from the ground and connect it with the horizontal boreholes in the adjacent floors and the goaf, draining the adjacent