Extraction of hidden and unstable landslide masses and their risk assessment

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H02744
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 海外学術
• Research Field: Geotechnical engineering
• Research Institution: International Consortium on Landslides (2018); Yokohama National University (2016-2017)
• Principal Investigator: Konagai Kazuo 特定非営利活動法人 国際斜面災害研究機構, その他部局等, 学術代表 (50126471)
• Co-Investigator(Kenkyū-buntansha): 松島 亘志 筑波大学, システム情報系, 教授 (60251625) ; 清田 隆 東京大学, 生産技術研究所, 准教授 (70431814) ; 竹内 渉 東京大学, 生産技術研究所, 教授 (50451878)
• Research Collaborator: Ikeda Takaaki ; Mohan Pokhrel Rama
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 斜面災害 / 地形変動 / 国土保全 / ネパール・ゴルカ地震

Outline of Final Research Achievements

The Gorkha Earthquake of April 25, 2015, Nepal, has caused many landslides along the Trishuli River in Himalayas where a straightforward method to analyze every detail of slope movement is difficult for seeing the whole picture of the disaster. A numerical approach has been taken to assess the remaining risk of landslides. The debris mass movements are described in simulations with only four parameters, namely, the critical angle, Gauckler-Manning roughness coefficient, angle of repose, and the rain concentration, an index to describe rain-water collectivity of gulleys. The optimum set of these parameters, obtained through a batch of numerical simulations to minimize the prediction error, was then used to identify locations of unstable colluvium deposits remaining along gullies on steep valley walls of the Trishuli River.

Free Research Field

工学

Academic Significance and Societal Importance of the Research Achievements

2015年ネパール・ゴルカ地震が襲った当該地域はヒマラヤの山中にあってアクセスも困難で、多数の崩壊の中で特定の斜面崩壊だけに特化した調査は現実的ではない。本研究は、広域の斜面災害の全体像を、数を絞った物理的パラメータで的確に迅速に把握し、地震後も変形が継続する斜面への対応検討の事例を示したものであり、ネパールに限らず、類似の被害が広域かつ多数に及び人的・物的資源も限られた状況での復旧戦略策定への貢献につながる道筋を示したところに学術的・社会的意義がある。