| 摘要 |
PURPOSE:To quickly form a pile pit in the boulder basalt rock layer by a method in which an auger is provided in an inner tube of a high-pressure water tube, a high-pressure water jet nozzle is provided in the lower end between both the inner and outer tubes, and the auger is turned in the opposite direction to the turning direction of both the inner and outer tubes. CONSTITUTION:Drivers 10 and 16 are lowered along a guide 17 by wire ropes 18 and 19, and inner and outer tubes 1 and 2 are turned to form a pile pit 25 by the cutting blade 11 of an auger 12. When the tumbling stone 26 of basalt rock is touched by the blade 11, high-pressure water is jetted from a nozzle 6 through a high-pressure water tube 5 while turning the auger 12 and the inner and outer tubes 1 and 2 mutually in the opposite direction to excavate the tumbling stone 26. The excavation is further made by the blade 11. Even when the inner and outer tubes 1 and 2 come into contact with the boulder stone 26 and the turning direction is varied, the variation of the turning directions is offset because the auger 12 is turned in the opposite direction, and vertical pile pit can thus be formed. |
