| 摘要 |
PROBLEM TO BE SOLVED: To provide a structurally simple, surely operable and inexpensive overturning waterproof door requiring no large housing space and reducing maintenance. SOLUTION: A door body 4 also serving as a lid is rotatably arranged in a steel pit 2 of an upper opening arranged on a floor surface 3 of passage part 1 of a structure with the structure inside as the axis, a hollow rubber floating body 20 is fixed to the reverse side of the door body 4, and the floating body 20 and an external gas compressing cylinder 27 are connected via an operation valve 29. When the periphery of the structure becomes a flooding state by a heavy rain or the like, gas is made to flow in the floating body 20 by operating the operation valve 29 to raise the door body 4. Thus, flooding rainwater infiltrates into the steel pit 2 from clearance to put the door body 4 in a standing-up state by buoyancy and hydrostatic pressure of water. The door body 4 is supported in the whole width direction by expansive force of the floating body 20, and the passage longitudinal directional length of the door body 4 is shortened to reduce weight. Since the operation valve 29 and the gas compressing cylinder 27 are out-fitted, execution work becomes simple to reduce a cost.
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