| 摘要 |
PROBLEM TO BE SOLVED: To provide an underwater ground improvement method having no need of disposal by improving the ground in an original position and to make it possible to reduce a construction cost as well as a disposal cost. SOLUTION: An improvement device is equipped with vertical drain members 10, an air-tight box body 12 and a water absorption device 14. The box body 12 is equipped with a main body 12a having the closed upper end and opened lower end, and the main body 12a is made to pass through the underwater ground 16 so as to surround the peripheral surfaces of the drain members 10. The water absorption device 14 is equipped with a vacuum pump 14b, and a pipe 14c linking and connecting one end thereof to a tank 14a is connected to a perforated pipe 12b provided to the inside of the box body 12. When the vacuum pump 14b is driven, the water in the main body 12a is discharged to the outside, and then, water in the underwater ground 16 collected through the drain members 10 is discharged to the outside. When the water is continuously discharged, the pressure in side the box body 12 is drecreased, and this pressure drop and the pressure difference between the hydraulic pressure applied to the box body 12 and the dead load are used to make consolidation settlement of the underwater ground 16 in an original position in part which the drain members 10 are buried.
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