In this study, a new horizontal pre-drainage system is suggested.
在这项研究中，一个新的横向预排水系统被建议。
2
The field test indicated that the developed drilling rig is appropriate for underground pre-drainage of coal seams.
现场试验表明，这是一种适于井下工作面钻进瓦斯预抽放短钻孔的轻便高效钻机。
3
An effective pre-drainage system in a limited area that has a high water head and huge inflow is important to prevent flooding accidents during subsea tunnelling.