Reseach on the mechanism of scour and suction due to a tsunami and waves, and development of general-purpose predicting methods

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K04667
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 25030:Disaster prevention engineering-related
• Research Institution: Tokai University
• Principal Investigator: Yamamoto Yoshimichi 東海大学, 工学部, 教授 (70366087)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 津波災害 / 高波災害 / 洗堀 / 吸出し / 底質の中央粒径 / 底質の均等係数 / 底質の乾燥密度 / 津波漂流物の衝突力

Outline of Final Research Achievements

1) We developed wide range diagrams for estimating bed load coeficients simply for a numerical model which can predict a flood and a topographical change by a tsunami, and presented a planning method of tsunami measures and application examples in the ISOPE international conference and Journal of JSCE in 2018 and 2019, and JMSE in 2020. Moreover, we presented comparison results of main formulae for estimating impact forces by tsunami driftage in JMSE in 2021.
2) We developed a numerical model which can predict sand outflow rates from any dike or any seawall, and presented the results of verification simulations using field data in the ISOPE international conference, English Journal of JSCE, and JMSE in 2019. Furthermore, since we could extend this numerical mode to 3-dimensinal model, will presenting results of simulations using field data as soon as possible.

Free Research Field

海岸防災

Academic Significance and Societal Importance of the Research Achievements

１）一般の技術者が利用できないスーパー・コンピュータでなく、通常のPCで、海岸林や堀による浸水低減効果に加えて、海岸堤防や命山周辺の洗堀も考慮できるように、平面2次元数値予測モデルを改良してきたが、さらに、経験的に決定していた漂砂量係数を底質の中央粒径、均等係数、乾燥密度をパラメータに簡単に決定できるよう工夫し、面的防護の計画・設計を低コストで合理的に実施出来るようにした。
２）極浅海域や砂浜上の高波による堤体破壊は、洗掘・吸出しが主原因である場合が多いので、これらを考慮した唯一の堤防・護岸安定性評価法を提案し、堤体からの裏込め材吸出し量算定モデルを任意形状の三面張り、三次元モデルへ拡張できた。