Study on the destructive process of coastal structures by inundating tsunami wave force

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04278
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22040:Hydroengineering-related
• Research Institution: Kagoshima University
• Principal Investigator: Nagayama Akio 鹿児島大学, 理工学域工学系, 助教 (40621438)
• Co-Investigator(Kenkyū-buntansha): 田中 智行 広島大学, 先進理工系科学研究科(工), 准教授 (20452609) ; 柳川 竜一 香川高等専門学校, 建設環境工学科, 准教授 (70649095)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 津波波力 / 戻り流れ / ビル構造物

Outline of Final Research Achievements

The 2011 Tohoku region Pacific Ocean earthquake caused a huge Tsunami wave that broke many shore area buildings and structures. In Japan, most of the estimated formulas are based on the assumption of static water depth pressure, have adopted three times the pressure, and calculated the wave force on the building structures. However, the formula only focuses on swash waves caused by limited experimental apparatus scale, which needs to cover the return wave condition more. For these reasons, we have discussed modifying the formula at the return wave using a large water tank in the laboratory. We pointed out that 1) the tsunami force during the return wave is the same as the swash wave in the water concentration areas, 2) the modified formula may estimate the wave force that depends on the building shape, such as frontage, and 3) we modified the formula, including the drag force from side wall velocity, and discussed the wave force during the return wave.

Free Research Field

水工学

Academic Significance and Societal Importance of the Research Achievements

東北地方太平洋沖地震で発生した地震津波は東北から関東の沿岸域で遡上し、沿岸域の構造物群を破壊した。その後の被災調査では、従来の浸水深を基礎とした被災想定と現実の被災状況は大きく異なることが指摘された。以上より、本研究は従来の開口影響を考慮した陸上構造物に作用する津波持続荷重の推算式に修正項を追加し，戻り流れ時の作用波力の推算の高精度化に関して一定の成果を得た点に学術的意義がある。また本研究の成果は、巨大地震津波の遡上津波による構造物群の被災推定の高精度化に繋がり、被災後の迅速な復興活動に質する基礎的な情報を提供できる点に社会的な意義がある。