Tsunami countermeasure work and tsunami countermeasure construction method

摘要

PROBLEM TO BE SOLVED: To provide a tsunami countermeasure for alleviating tsunami damage at a lower cost than a tsunami floodgate without requiring operation such as floodgate closing work when hit by the tsunami.SOLUTION: A tsunami countermeasure 10 comprises an impermeable wall 18 to reflect a high tidal wave TU fixed on a bottom of water 22 with piles 20. Being constructed in a marine area 16 facing a river mouth section 14, the impermeable wall 18 can be fixed with the piles 20 having large section areas without being subject to a limitation (no more than 4% of a section area of a river) applied when constructed in the river 12. A section deeper than a lower section of the impermeable wall 18 allows a wave or a water flow to pass through between the piles 20 which support the impermeable wall 18. Because the impermeable wall 18 can be constructed with a height of the lower section thereof higher than a predetermined tide level, the impermeable wall 18 can reflect the high tidal wave TU and prevent the same from attacking the river 12.