| 摘要 |
PURPOSE:To reduce the cost of a structure for icy sea by a method in which a superstructure for working is supported on the upper end of a columnar leg erected on a sub-surface structure to be landed on the seabed, and an intermediate float with a ballast tank and a water supply and discharge device is set on the columnar leg in a vertically movable manner. CONSTITUTION:A superstructure 4 with an excavator for the seabed is supported on the upper end projected from the sea surface of a columnar leg 3 erected on a sub-surface structure 1 with a ballast tank 2. An intermediate float 5 with a ballast tank 6 and a water supply and discharge device is provided to the leg 3 in a vertically movable manner to make up a structure for icy sea. The structure is towed to a construction site, and water is supplied into the ballast tank 2 of the structure 1 to cause the structure 1 alone to settle under the condition that the float 5 is floated on the water surface. After the structure 1 is landed on the seabed 8, water is supplied into the tank 6, and the float 5 is sunk and set on the structure 1.
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