| 摘要 |
PURPOSE:To effectively and continuously discharge excavated soil by a method in which the inside of a tube is excavated by a hammer grab until a spring- water ground layer is reached, fresh water is charged into the excavated pit and discharged with soil by an underwater pump for treating sediments, and the tubes are engrafted successively, followed by repeating the same operations. CONSTITUTION:Underwater pumps 8 and 14 are set to the first and second water tanks 7 and 13 provided on the ground's surface near a casing tube 2 in such a way as to enable water in the tank 7 to be charged through into the tube 2. The water tank 13 connected to the tank 7 through a pileline 15 is connected through a pipeline 12 to the inside of the tube 2. When a spring- water ground is reached by excavation using a hammer grab, water is charged from the tank 7 into the tube 2 in place of the grab and the water and soil are discharged by the pump 10 to the tank 13, where sediments on the bottom are treated. Supernatant water in the tank 13 is circulated to the tank 7, and the tube 2 is engrafted and pressed-in. The same operations are repeated until a predetermined excavation depth is reached.
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