The multi-scale dynamics in granular flow considering stick-slip phenomena

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K18901
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Research Field: Civil engineering and related fields
• Research Institution: Nagoya Institute of Technology
• Principal Investigator: MAEDA Kenichi 名古屋工業大学, 工学(系)研究科(研究院), 教授 (50271648)
• Research Collaborator: Muir Wood David ; Take Andy
• Project Period (FY): 2017-06-30 – 2019-03-31
• Keywords: 土石流 / スティック・スリップ / マイクロメカニクス / マルチスケール / 粒状体 / フルード数 / 限界状態 / 配位数

Outline of Final Research Achievements

The mechanism of dry granular flow was examined in micro and macro views. First, flow behaviors of dry granular materials on a slope were examined using PIV image analysis and a DEM in two dimensions. The simu-lation results replicated the tendencies shown in the test model results. Relationships exist between macro and micro behaviors during phenomena such as velocity distributions in depth stratification and uplifts of large particles that change flow grades. Similarly, stress chains are transmission paths of contact forces, this study's discussion focus. The distribution of the averaged coordination number was found to correspond to the distribution of velocity, indicating three layers of structure. This stratification could be explained by the state parameter, a relative variable dependent on void ratio, mean normal stress, and critical state. Moreover, the stress chains formed from the riverbed concentrated the larger particles and pushed them upwards to-wards the flow surface.

Free Research Field

地盤工学

Academic Significance and Societal Importance of the Research Achievements

本研究が，理学，工学などの幅広い分野で着目される粒状体流れの力学的体系や方向を大きく変革，転換するブレイクスルーの切欠になると考えられる。流れの代表的特徴をスティック・スリップとして捉え，その単純明快な物理モデルと粒子性と波動性の二重性で捉える視点によって粒状体力学の画期的な進展が図られたり，流れの合理的な特徴の表現や分類を可能にすることで，粒状体流れの様々な現象の統一的理解が促進される．
流れ中に巨石が表面に浮き上がる現象や分級のメカニズムに新たな統一的解釈を与えることで，さらに粒状体流れを捉える新しい原理や土砂災害軽減のための提案が期待される．