Mechanism of crack initiation at impounding fill dams by a large earthquake

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K08012
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Rural environmental engineering/Planning
• Research Institution: National Agriculture and Food Research Organization
• Principal Investigator: TAGASHIRA Hidekazu 国立研究開発法人農業・食品産業技術総合研究機構, 農村工学研究部門, ユニット長 (40414221)
• Co-Investigator(Kenkyū-buntansha): 増川 晋 国立研究開発法人農業・食品産業技術総合研究機構, 農村工学研究部門, 研究領域長 (00414459) ; 向後 雄二 東京農工大学, (連合)農学研究科(研究院), 教授 (30414452)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: フィルダム / 地震 / 亀裂 / 貯水 / 遠心載荷振動模型実験 / 画像解析 / FEM解析

Outline of Final Research Achievements

Dynamic centrifuge model tests, image analyses and FEM analyses were carried out in order to investigate the mechanism of crack initiation at impounding fill dams by a large earthquake.
In the model tests, we found that longitudinal cracks tended to occur on the both side slopes a little bit down from the dam crest in the easy stage of crack initiation and development with and without water storage. FEM analyses showed the concentration of horizontal strain and shear strain in those areas during a shake. Image analyses indicated that the distributions of displacement and strain after an earthquake had a symmetry about upstream side and downstream one in the case of no pounding condition, while they had an asymmetry in the case of pounding one and that the water storage moved the dam body to the downstream side during a huge earthquake.

Free Research Field

ダム工学

Academic Significance and Societal Importance of the Research Achievements

本研究では、フィルダムが大地震を受けた場合に、堤頂から少し下がった斜面に早い段階の亀裂が長手方向に発生する結果を得た。斜面部は堤頂部に比べて整地状況が劣ることや亀裂の隙間が閉じ易いことから現地で目視で識別し難い場合が多いが、実際にはダメージを受けている可能性があることを示唆している。ダム堤体の安全性への影響は別途に検討する必要があるが、地震後に重点的に調査すべき箇所を提示することができた。