Mechanism of debris flow investigated by a novel measurement technique of sediment concentrations

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K03759
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17030:Human geosciences-related
• Research Institution: Kyoto University
• Principal Investigator: Shusuke Miyata 京都大学, 防災研究所, 助教 (80573378)
• Co-Investigator(Kenkyū-buntansha): 長谷川 祐治 広島大学, 総合科学研究科, 准教授 (60342664) ; 中谷 加奈 京都大学, 農学研究科, 助教 (80613801)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 水路実験 / 細粒土砂 / 液相 / 間隙流体

Outline of Final Research Achievements

We developed a technique of measuring sediment concentrations in a sediment laden flow. The measurement method was improved throughout a flume experiment. The sediment concentration measurement system was installed in a creek with frequent debris flows. Direct evidence of high ratio of sediment (0.5-0.7) in the pore fluid of a debris flow was obtained by our observation.
Based on a flume experiment and simulations, we proposed a method to estimate spatiotemporal density of the pore fluid in a debris flow. Debris flow experiments with various bed conditions revealed that deposition was enhanced under conditions of unsaturated stream bed rather than saturated stream beds.

Free Research Field

砂防学

Academic Significance and Societal Importance of the Research Achievements

本研究で新たに明らかとなった土石流の流動中および堆積に関する知見は土石流シミュレーションの改良に資すると期待される。特にこれまでのシミュレーションで想定された到達範囲を超えるような土石流に対するシミュレーションが改善されると考えられ，ハザードマップの高度化を図ることができる。