| 摘要 |
PROBLEM TO BE SOLVED: To provide a construction method for backfilling underwater depressions and capable of reducing the spreading of turbid water and hypoxic water to peripheries as a backfilling material is thrown in an underwater depression. SOLUTION: A self-contained pollution prevention film 3 is made to surround a throw-in region A of the backfilling material 2 to the underwater depression 1, and the backfilling material 2 is thrown in the throw-in region A from an earth carrying barge 10. A workboat 11 pumps up mixed water (hypoxic turbid water) of turbid water and hypoxic water which occur at this time by a pump 12. Pumped-up hypoxic turbid water is fed to a gas-liquid mixing device 13 on the workboat 11, and air is dissolved in and mixed with this to form highly concentrated oxic water and fed to a hopper of an earth carrying barge 14 as a solid-liquid separating device. Since solid particles precipitate to make the separation between solid and liquid to progress in the hopper of the earth carrying barge 14, fresh water, a supernatant, is made to overflow from the hopper and flow back to the vicinity of a bottom via an effluent pipe 21 and agitated and mixed with a bottom-layer water in a hypoxic state. COPYRIGHT: (C)2009,JPO&INPIT
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