When raising seawalls due to building height restrictions is difficult, as in the case of airport facilities, wave-dissipating works with a notch are used between wave-dissipating works and seawalls to increase the crown width. The notch part is important for the security activity. Even in the future, it will be widely used in the wave-dissipating block layers in offshore airports. Nevertheless, there is a limited amount of research on wave-dissipating works with a notch at the rear end of the crown that exist. The hydraulic model experiments were subsequently conducted to clarify the wave pressure characteristics of two covering forms of wave-dissipating works: the fully covered method and the two-layer method. The results of the experiments revealed that the difference in wave-dissipating work form has little effect on the wave pressure and that the wave pressure acting on upright walls in the case of the wave-dissipating work with a notch is 13% greater than that in the case without a notch in terms of the fully covered form and 9% greater than that in the case without a notch. In this way, it was indicated that notched wave-dissipating works reduce the stability and dissipating performance of the blocks compared to the normal works without notches. Therefore, caution should be exercised when using notched wave-dissipating works, and hydraulic model experiments are recommended to confirm stability and wave pressure performance.

防波扉は折りたたみ式の可動式津波低減設備で，津波発生時に自動的に起立して波の浸入を防ぐ．本研究では，防波扉の実用化に必要とされる条件を，水理模型実験と数値解析の両面から検討した．OpenFOAMを用いて数値解析モデルを構築し，津波低減効果の評価を行った．波高計測値のみで防波扉の性能を評価する手法は，堤体の正味の津波低減効果を正当に評価できておらず不適切であった．一方，通過水量データでの評価は，堤体の津波低減効果を最も適正に評価しており，防波扉の津波低減効率は7割以上を示した．防波扉の強度分析では，ヤング率が大きい木材の場合，防波扉を強度面で安全に運用できると判断した．検討結果を踏まえて，防波扉は津波対策防災設備として実用性が認められると判断し，防波扉の現場設置モデルを提案した．