Model development to evaluate huge landslide focusing on variable sediment storage in the catchment

2016 Fiscal Year Final Research Report

• Project/Area Number: 26292077
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Forest science
• Research Institution: University of Tsukuba
• Principal Investigator: HOTTA Norifumi 筑波大学, 生命環境系, 准教授 (00323478)
• Co-Investigator(Kenkyū-buntansha): 山川 陽祐 筑波大学, 生命環境系, 助教 (20611601) ; 土屋 智 静岡大学, 農学部, 教授 (60197720) ; 執印 康裕 宇都宮大学, 農学部, 教授 (60221305) ; 早川 裕弌 東京大学, 学内共同利用施設等, 准教授 (70549443) ; 今泉 文寿 静岡大学, 農学部, 准教授 (80378918)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 土石流 / 土砂流出 / 大規模崩壊地 / 土石流対策

Outline of Final Research Achievements

Detailed field measurements of debris flow in the Ohya landslide revealed two issues to be solved for model development to predict sediment dynamics after huge landslide occurrence. One is influence of particle size distribution of debris-flow material on the fluidity. The other is meandering of debris flow on a debris fan at the bottom of catchment. The influence of particle size distribution was appeared as liquefaction of fine particles. Also, some of solid particles merely contribute to static stress without any contribution to dynamic stress. The particle size affected the meandering on a debris-flow fan as well. Experiments with uniform particle size showed straight descending on a debris-flow fan, while debris flows with mixed particle size showed meandering on the fan leading asymmetrical and variable final shape. Accumulation of coarse grains at the debris-flow front induced rapid and unsaturated deposition at the fan apex and possibly caused the following meander movement.

Free Research Field

砂防工学，森林水文学