2013 Fiscal Year Final Research Report
Effects of drought preceding rainfall on slaking-induced slope instability
| Project/Area Number |
24656282
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Single-year Grants |
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| Research Field |
Geotechnical engineering
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| Research Institution | The University of Tokyo |
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Principal Investigator |
KIYOTA Takashi 東京大学, 生産技術研究所, 准教授 (70431814)
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| Co-Investigator(Renkei-kenkyūsha) |
KONAGAI Kazuo 横浜国立大学大学院, 都市イノベーション学府, 教授 (50126471)
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| Project Period (FY) |
2012-04-01 – 2014-03-31
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| Keywords | スレーキング / 斜面崩壊 / 一面せん断試験 / 地盤災害 / 泥岩 / 室内土質試験 / 干ばつ / 豪雨 |
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| Research Abstract |
This study investigates the effects of wetting and drying on the strength and deformation characteristics of mudstone, known as slaking. When rainfall-induced landslides occur, the intensity-duration of precipitation is often examined, but the drought conditions preceding the landslide-inducing rainfalls are not usually considered. The author proposed a hypothesis that such drought and rainfall cycles would accelerate slaking on the geo-materials. First, we undertook to collect landslide data from various sources in order to identify slaking-induced landslides. Second, a series of direct shear tests was conducted by simulating cyclic drying and wetting (D/W) under different stress condition. Considerable creep deformations on crushed mudstones were found during both D/W phase, and a gradual decrease of friction angle was observed with the increasing number of D/W. Higher slaking index, lower water content before wetting and lower initial density accelerate the slaking of geo-materials.
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