日本煤矿瓦斯抽放始于1934年,至今已有46年历史,目前年抽放量为4亿米~3左右。日本主要是以未开采煤层瓦斯抽放(本煤层瓦斯抽放)和邻近层瓦斯抽放为主。现将主要抽放瓦斯方法分述如下:一、未开采煤层瓦斯抽放未采煤层(本煤层)抽放瓦斯方法主要有:①由底板或顶板巷道打穿层钻孔抽放; Japan’s coal mine gas drainage began in 1934, has been 46 years of history, the current drainage volume of 400 million meters to 3 or so. Japan is mainly dominated by gas drainage from unleached coal seams (gas drainage from the coal seam) and gas drainage from nearby layers. Now the main method of gas drainage are as follows: First, unburdened coal seam gas drainage Unseamed (the coal seam) gas drainage methods are: â ’¢ drilling or drainage through the floor or roof tunnel;