Improvement of mixed sediment model considering clay loss and extension to sand-gravel mixture

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K14837
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 22040:Hydroengineering-related
• Research Institution: Nagoya University
• Principal Investigator: Cho Yonghwan 名古屋大学, 工学研究科, 特任講師 (00761082)
• Project Period (FY): 2020-04-01 – 2022-03-31
• Keywords: 粘土流失 / 乾燥かさ密度 / 幾何学的構造 / 混合土砂モデル / 干潟 / 斜面崩壊 / 含有率 / 流失活性層

Outline of Final Research Achievements

This research presents the improvement of the mixed soil model focusing on the dry bulk density of mixed soil and the investigation of the effect of mud fraction on the movement of mixed soil consisting of sand and clay. The research is composed of hydraulic experiments and numerical simulations. The hydraulic experiment obtained the relationship between mud fraction and the dry bulk density of the mixed soil, which was used for sediment transport calculations of the mixed soil model. The mixed soil model was improved based on the geometric structure with the dry bulk density of the mixed soil. Using the improved mixed soil model, the characteristics of clay loss, the effect of mud fraction on topographic changes, and the numerical stability of mixed soil slide calculations considering the bed-load of mixed soil were investigated.

Free Research Field

海岸工学

Academic Significance and Societal Importance of the Research Achievements

改良した混合土砂モデルは，河川分野で提案された混合土砂の理論を海岸分野まで拡張し，粘土と砂の移動特性を考慮することで，混合土砂の侵食・堆積だけではなく，粘土の時間的・空間的な移動傾向および分布，粘土の流失機構等，混合土砂の移動傾向を明らかにすることができた．また，構築したモデルを人工干潟における粘土の動的管理に活用することで，地球温暖化防止のための注目されているブルーカーボン生態系の造成に一助できることが期待される．また，混合土砂の掃流移動計算の可能性が確認され，混合土砂モデルの適用範囲を砂と礫からなる混合土砂の漂砂計算まで拡張する基礎を設けたと考えられる．