2021 Fiscal Year Final Research Report

Study on developing a new method caputuring large wood with horizontal rods

Research Project

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Project/Area Number	19H02993
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Review Section	Basic Section 40010:Forest science-related
Research Institution	Mie University
Principal Investigator	Tsutsumi Daizo 三重大学, 生物資源学研究科, 教授 (40372552)
Co-Investigator(Kenkyū-buntansha)	堀口俊行防衛大学校(総合教育学群、人文社会科学群、応用科学群、電気情報学群及びシステム工学群), システム工学群, 准教授 (30795703) 内田太郎筑波大学, 生命環境系, 准教授 (60370780) 鈴木拓郎国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員等 (60535524)
Project Period (FY)	2019-04-01 – 2022-03-31
Keywords	流木 / 土砂災害 / 捕捉工 / 水平梁 / 水路実験 / 粒子法 / 透過型砂防堰堤 / 流木捕捉率
Outline of Final Research Achievements	For the development of a new type of large wood trap with horizontal rods, we conducted flume experiments, numerical simulations, and consideration of practical use. From results of the flume experiment, in which sediment and large wood were supplied at the same time, it was confirmed that the large wood was trapped on the horizontal rods, and the sediment flowed downstream, passing under the trap. It was confirmed that the large wood trap rate differs depending on the large wood supply density, the grain size of the sediment, ratio of the large wood length to the rod spacing. The results of these experiments were simulated by numerical simulation using the moving particle method, and although there were some differences, the results were similar to those of the experiments. Similar results were obtained with the result of scaling up 100 times based, indicating the possibility of practical application.
Free Research Field	砂防工学
Academic Significance and Societal Importance of the Research Achievements	豪雨によって斜面崩壊や土石流が発生する際，樹木が土砂と同時に流出し，河川を流下する。近年，この流木が橋梁などの河川狭窄箇所を閉塞し，土砂や水が越流・氾濫することで，被害が拡大する現象が多発している。最近になって，種々の流木捕捉工が提案されているが，砂防ダムや遊砂池に併せて設置されることが多く，設置場所が限られ，施設が大規模化する問題点がある。本研究で検討した水平梁構造の捕捉工は，流木と土砂を分離して流木のみを効率的に捕捉する機能を有することが水路実験と数値解析で確認された。砂防堰堤等の施設が未設置の河川に設置することで，下流への流木の流出を防止し，流木災害の軽減が期待される。