1·Under gassy coal seam condition, the full-heading development is employed. Because of the fast heading a high rate of gas emission arises.
在瓦斯含量较大的煤层采用综掘掘进巷道，由于掘进速度快，出现了瓦斯涌出量过大的现象。
2·Gas drainage in high gassy coal seam with low gas permeability is always an hard solved significant technology problem in the process of safety production.
高瓦斯低透性煤层的瓦斯抽放，一直是煤矿安全生产过程中的重大技术难题。