篇篇学之5：Hydraulic tunnels

战火财神

In the above articls,we have described the types of dams.Here we will discribe the tunnels.
A tunnel is an underground passage usually made without removing the overlying rock or soil.Although the tunnels are approximately horizontal.they must be built with sufficient gradient for proper drainage.tunnels may be ventilated by shafts leading to the surface or by exhaust fans at the ends.
Tunnels are dug in various types of materials,from soft clay to hard rocks.Depending on the types of soil,a method of excavation is chosen.When digging soft clays,the New Austrian Tunnelling method or NATM is used.When digging in weak rocks a tunnel boring machine or TBM is used.In hard rocks blasting is usually the fastest method,as in the Norwegian tunnelling method.
WORDS:
hydraulic tunnel    水工隧洞      approximately    近似地     sufficient     足够的      gradient   梯度
drainage   排水       ventilated      通风的      shaft       柱状（通气孔）       exhaust   抽风机
excavation   挖掘    NATM（NEW AUSTRIAL TUNNEL METHOD)新奥法    TBM(TUNNEL BORING MACHINE)隧道钻机
boring machine   钻机      blast     爆破        Norwegian    挪威的                                               

zhoudazhong9810

等了几天了，终于看见了第五篇。支持scuyangjing版主。
                 

苦作舟

前几天休假，没时间上网，进度推迟了些！
望关心专业外语的同志见谅！                 

kxwsb

不错  比较专业啊  多谢楼主分享  希望能够不断坚持下去                  

不再回头

又来学英语了，水工隧道 ^_^                 

niuniu938167

学习方式很好，希望楼主坚持下来，我会一直支持你的