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1概况在我国以三峡工程和京九铁路为代表的许多电站、坝基、高层建筑和桥基础等重点建设项目施工中，大直径钻孔灌注桩经常遇到大卵砾石、坚硬石英一花岗岩块球体等难钻进地层。在这些地层中目前尚无较经济的施工方法，采用传统的滚刀钻头钻进，钻头寿命较低，极易损坏。同时，
1 Overview In China’s construction of key construction projects such as the Three Gorges Project and the Beijing-Kowloon Railway, such as power stations, dam foundations, high-rise buildings and bridge foundations, large diameter bored piles often encounter large gravel, hard quartz-granite blocks Difficult to drill into the formation. There is currently no more economical method of construction in these formations. Drilling with conventional hob bits has a lower life expectancy and can be easily damaged. Simultaneously,