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2019 Fiscal Year Final Research Report

Study on the setting and cancellation timing of the reference rainfall for warning and evacuation after a large-scale earthquake

Research Project

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Project/Area Number 16K01325
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Research Field Natural disaster / Disaster prevention science
Research InstitutionShinshu University

Principal Investigator

HIRAMATSU Shinya  信州大学, 学術研究院農学系, 教授 (70294824)

Co-Investigator(Kenkyū-buntansha) 小野 裕  信州大学, 学術研究院農学系, 助教 (00231241)
福山 泰治郎  信州大学, 学術研究院農学系, 助教 (60462511)
Project Period (FY) 2016-04-01 – 2020-03-31
Keywords大規模地震 / 警戒避難基準雨量 / 斜面安定 / 土質強度 / 地震後の経過時間 / 加速度
Outline of Final Research Achievements

When an open crack is formed by a large-scale earthquake, the groundwater depth downstream of the open crack increases sharply, and the critical rainfall for landslides decreases by up to 18%.
It became clear that the stability of the slope declines with the increase of the acceleration acting during the earthquake, and the stability of the slope declines more than 30% when the acceleration of 2.2G acts. Furthermore, when 0.85G and 2.2G acceleration was applied to the hillside slope, no clear recovery of the safety factor was confirmed even after 1 to 3 months. On the other hand, when a 3.0 G acceleration was applied to the hillside slope, the safety factor of the slope recovered to the same level as before the earthquake, 3 months after the earthquake .

Free Research Field

砂防学

Academic Significance and Societal Importance of the Research Achievements

地震規模や地震発生後の時間経過と土質強度さらには斜面の安定性との関係を定量化しようとした点に学術的意義が認められる。
本研究により,地震の規模や地震後の時間経過に対応した斜面の安定性の変化や崩壊発生限界雨量が明らかになった。そして,本研究で得られた知見を活用する事により,土砂災害に対する警戒・避難基準雨量の引き下げ率とその解除時期が明らかになるため,大規模地震発生後の警戒・避難体制の策定に大いに貢献することになり社会的意義は大きい。さらに,本研究成果を活用し発展させていくことにより,大規模地震発生後の流域内での土砂災害危険度評価や望ましい流域管理手法の確立に大きく貢献することが確信される。

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Published: 2021-02-19  

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