| 摘要 |
PROBLEM TO BE SOLVED: To provide a structure which can elevate a water-impervious wall according to the elevation of the water level, in the case of the elevation of the water level. SOLUTION: This structure comprises a water bath portion 1 having an introducing means which is capable of externally introducing water and having its upper surface opened, and a water-impervious wall 10 formed of a material which is lighter in gravity than water. When water is introduced from the introducing means into the water bath 1, the impervious wall 10 functions as a dike, a wall, or the like which can prevent water from entering from the outside by elevating the impervious wall 10 by the buoyancy.
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