防潮堤背後の海岸林が津波越流時の洗掘現象に与える影響に関する実験  [in Japanese] EFFECTS OF COASTAL FORESTS ON SCOURING BEHIND COASTAL EMBANKMENT INDUCED BY TSUNAMI OVERFLOW  [in Japanese]

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Abstract

レベル2津波に対しては,その被害を最小限とするために防潮堤裏法尻の洗堀を抑え,防潮堤が粘り強く耐えることが求められる.本研究では海岸林の減勢効果に着目し,防潮堤と海岸林を組み合わせた多重防護を対象とした移動床下における水理模型実験を行い,防潮堤と海岸林の配置方法の違いや防潮堤の高さの違いによる防潮堤背後の流況と洗堀現象について明らかにすることを目的とした.防潮堤の下流側に海岸林を配置することにより,防潮堤背後の水深が増加し,流速が低下することで防潮堤裏法尻における洗堀を抑えることができる.特に防潮堤の高さが低い場合には,海岸林による水深増加の影響がより上流側にまで及び,越流形態が潜越流となり,流れの主流が水面付近に移ることで防潮堤背後の洗堀をより抑えることができる.

 Coastal forest in the Tohoku and Kanto districts of Japan were destroyed by the Great East Japan tsunami on 2011. However, coastal forest had some ability to reduce the damage by a tsunami even when they were broken. In this study, the effects of coastal forests on scouring behind coastal embankment induced by tsunami overflow have been investigated by the hydraulic model experiments with erodible-bed. The scouring at landward toe of embankment becomes small with arrangement of coastal forest. Moreover, considering washed-out trees is not so much influenced on scouring size.

Journal

  • Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering)

    Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) 74(2), I_343-I_348, 2018

    Japan Society of Civil Engineers

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