| 摘要 |
PURPOSE:To lap excavated pits by a method in which vertical drive shafts are provided for a rotary driver and a strut in a vertically movable manner, a horizontal synchronous shaft is set and connected between the lower parts of the vertical drive shafts, and excavating blades are attached to the respective shafts for excavation by lowering and turning them. CONSTITUTION:A rotary driver 2 for vertical driving is actuated to turn the connecting shafts 18 and cutting and stirring shafts 5 of vertical drive shafts 3. The rotation of the shafts 18 is transmitted to a horizontal synchronous shaft 23 through bevel gears 18a and 22a to turn the shaft 23 and excavating blades 24. The drive shafts 3 are slowly lowered and soft ground is excavated to a given depth by the blades 5a and 24, thereafter, the shafts 3 are drawn out and then lowered in a repeating manner. During the period, an improving agent is jetted from the injection ports of the shafts 5 and mixed with excavated soil to form improved piles. Excavation work for soft ground to be improved can thus be smoothly performed, enhancing the efficiency of operations.
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