Proposal of a overflow river levee based on the internal erosion and surface erosion mechanism

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K04353
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22030:Geotechnical engineering-related
• Research Institution: Chubu University
• Principal Investigator: Sugii Toshio 中部大学, 工学部, 教授 (90196709)
• Co-Investigator(Kenkyū-buntansha): 余川 弘至 中部大学, 工学部, 講師 (20736087)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 堤防 / 間隙径分布 / 内部浸食 / 表面侵食 / パイピング

Outline of Final Research Achievements

So far, evaluations such as outflow and clogging of soil particles, which are conditions for internal erosion, had to be judged only by particle size and particle size distribution. In this study, we established a method to obtain the pore diameter distribution of soil from the water retention curve. In addition, the physical meaning of the pore size distribution obtained there, which was a problem, could be clarified using the idea of Kenney's granular filter. In practice, we proposed a method that can easily evaluate changes in the piping risk of embankments at the time of flooding if the shape of the embankment and the hydraulic conductivity are known even at the site. This will lead to real-time monitoring of not only flooding but also the risk of levee breakage without flooding, and is expected to serve as an index for information such as flood control measures and evacuation orders.

Free Research Field

地盤工学

Academic Significance and Societal Importance of the Research Achievements

本研究で得られた結果の大きな点は2点ある。第1点は、これまでの土中の間隙は平均的な値として取り扱ってきたが、本成果によりその大きさのバラツキを評価できる方法と物理的意味を明らかにすることができた。これにより、堤防の浸透、破壊に関する力学メカニズムの解明、精度の高い予測につながること、さらには土質力学に粒子レベルの考え方を取り入れ易くした。第2点は、越水なき破堤は、いつ破壊するかわからないのが、現場でも堤体の形状と透水係数がわかれば容易に評価することができる手法を提案できたことで、水防対策、避難指示などの情報としての利用ができ、豪雨災害に対する対応に大きく寄与するものである。