Development of a Practical Numerical Analysis Method for Designing a Retention Facility of Woody Debris

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K04375
• 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: Anan National College of Technology
• Principal Investigator: Osada Kengo 阿南工業高等専門学校, 創造技術工学科, 准教授 (30439559)
• Co-Investigator(Kenkyū-buntansha): 清水 義彦 群馬大学, 大学院理工学府, 教授 (70178995)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: 水工水理学 / 流木災害 / 洪水 / 防災減災

Outline of Final Research Achievements

This study presents a new 3-D numerical model to explain the woody debris conveyance and accumulation processes in rivers with piers or a debris retention facility. This model combines a 3-D flood flow model and a 3-D distinct element method (DEM) for simulating woody debris behavior. The most characteristic of this model is that the 2-D and 3-D hybrid flow model is adopted for the flood flow analysis. This hybrid approach led the method to run much faster than did a full 3-D flow simulation, and the method effectively obtains information regarding 3-D flow velocity. The method was calibrated and validated using flume data on woody debris conveyance and accumulation. Comparison of the method’s predictions and the flume results showed that the proposed method is capable of accurately simulating woody debris conveyance and accumulation in rivers with bridge piers or a debris retention facility.

Free Research Field

水工水理学

Academic Significance and Societal Importance of the Research Achievements

流木による災害を軽減するために，流木補足工や貯木池などの対策施設が計画・設計される．このような対策施設の立案は，現状では主として模型実験により施設設計が行われているが，検討段階で数値解析を活用できれば，検討の幅が広がり，より有効な施設設計が実施できる．本研究で構築した3次元流木解析モデルは，流木の流下過程，堆積形状，堆積割合，堆積による水位上昇といった流木対策施設を設計する上で基本的に知りたい情報を得ることが可能で，施設設計の高度化・効率化に向けて有用なツールになり得ると考えられる．