| Project/Area Number |
19K15102
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 22040:Hydroengineering-related
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| Research Institution | Chuo University |
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Principal Investigator |
Gotoh Takahisa 中央大学, 研究開発機構, 機構准教授 (70634682)
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| Project Period (FY) |
2019-04-01 – 2023-03-31
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| Project Status |
Completed (Fiscal Year 2022)
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| Budget Amount *help |
¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
Fiscal Year 2021: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2020: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2019: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Keywords | 掃流砂 / 浮遊砂 / 河床変動解析 / 準三次元解析 / 非平衡流砂モデル / 洪水流・河床変動解析 / 非平衡流砂運動 / 準三次元解析法 / 洪水流・河床変動解析法 / 二相流的解析 |
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| Outline of Research at the Start |
本研究では，掃流砂層内の流れと流砂運動，乱れの変化を二相流的に扱うことで流れと掃流砂の非平衡運動を考慮し，掃流層内から非平衡的に巻き上げられる浮遊砂を定量的に評価する水深積分型の洪水流河床変動解析法の開発する．そして，開発した解析法を土砂移動量が大きく河床波の発達が発達した既往の移動床実験や，洪水時の土砂移動の激しい砂河川（斐伊川等）に適用し，本解析法の妥当性と有効性を確認する．
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| Outline of Final Research Achievements |
In this study, we developed a new riverbed deformation analysis method that considers the non-equilibrium motion of bed load and suspended sediment by treating flow and sediment movement as a two-phase flow. It was applied to the movable bed experiment with the bridge pier, and the scouring in front of and around the pier and the sedimentation behind the pier were explained.
However, since actual rivers have mixed grain sizes, it is difficult to calculate the sediment motion equation for each grain size in consideration of the interaction with the flow.
Therefore, the developed calculation model was simplified and applied to the August 1981 flood at the mouth of the Ishikari River, where suspended sediments were predominant. As a result, it was able to explain the three-dimensional flows, suspended sediment movements and bed variations due to compound meandering channel flows.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究では，従来は掃流砂と浮遊砂を別個に評価していた河床変動解析法に対して，乱流場を考慮した粒子の運動方程式を解析することにより，乱れの作用により掃流砂から浮遊砂へ遷移する過程を評価し，掃流砂と浮遊砂の運動を一体的に扱う新しい河床変動解析法を開発している．
これにより，細粒土砂の多い河川で克つ土砂移動の非平衡性の強い河口付近の河床変動や河床波の発達・変形，構造物周辺の河床変動等を，より力学的に忠実に流れと土砂移動現象を理解することが出来，今後の対策の検討にも応用できる．
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