英语翻译Hard-rock tunneling.Short tunnels through hard rock are

英语翻译
Hard-rock tunneling.Short tunnels through hard rock are driven only from the portals,but longer ones usually are driven also from one or more intermediate shafts.Some long tunnels have been built with the aid of a small pilot tunnel driven parallel to the main tunnel and connected with it by crosscuts at intervals.The pilot tunnel not only furnishes additional points of access but also a route for removing muck and for ventilation ducts and drainage line.
Another method is the heading-and-bench system ,formerly used on most large tunnels because it required smaller amounts of powder and permitted simultaneous drilling and mucking ( removal of excavated material).The upper portion of the tunnel is driven ahead of the lower part which is called the bench .A separate crew is thus able to muck in the lower portion of the tunnel while the upper portion is being drilled .
With improvements in tunneling methods and machinery ,the full-face method of attack ,previously used only in small tunnels ,came into common use in building large ones .This change was partly brought about by the jumbo ,a movable platform on which numerous rock drills are mounted .By this device ,a large part of the tunnel’s face can be drilled at one time .The full-face method became the commonest and fastest way to drive a tunnel.

硬岩隧道.短隧道通过硬摇滚驱动入口,但只有从长标题通常是驱动也从一个或多个中间轴心.已经建了一些长隧道与援助的一个小飞行员隧道驱动平行于主要隧道,跟它相连的crosscuts间隔的时间.飞行员不仅提供附加分隧道的访问,也是一种路线为消除粪和通风管道和排水线.
另一种方法是heading-and-bench系统,以前用于大多数的大型隧道,因为它需要允许少量的粉末及同步钻井等特点的挖出物料(去除),上部的隧道是驱动下部的前面称为a分开的机组人员在板凳上,而可以在较低的部份优胜劣汰的隧道而上部正在操练.
改进方法和机械掘进中,正面攻击的方法,以前只用于小型隧道、进常用在建造大型的部分.这变化所带来的巨无霸,一种可移动平台,众多的凿岩安装.通过这种装置,有很大一部分隧道的脸可以钻在同一时间,正面方法成为最常见、最快的方式,开一条隧道.