| Project/Area Number |
15310127
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Natural disaster science
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| Research Institution | Kyoto University (2004-2005)
Kanazawa University (2003) |
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Principal Investigator |
WANG Fawu Kyoto University, Disaster Prevention Research Institute, Assistant Professor, 防災研究所, 助手 (10324097)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUMOTO Tatsunori Graduate School of Kanazawa University, Professor, 大学院・自然科学研究科, 教授 (10143877)
MIYAJIMA Masakatsu Graduate School of Kanazawa University, Professor, 大学院・自然科学研究科, 教授 (70143881)
MASUYA Horishi Graduate School of Kanazawa University, Professor, 大学院・自然科学研究科, 教授 (20157217)
WANG Gonghui Kyoto University, Disaster Prevention Research Institute, Assistant Professor, 防災研究所, 助手 (50372553)
SASSA Kyoji Kyoto University, Disaster Prevention Research Institute, Professor, 防災研究所, 教授 (30086061)
蔡 飛 群馬大学, 工学部, 助手 (20312902)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥12,400,000 (Direct Cost: ¥12,400,000)
Fiscal Year 2005: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 2004: ¥4,100,000 (Direct Cost: ¥4,100,000)
Fiscal Year 2003: ¥5,900,000 (Direct Cost: ¥5,900,000)
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| Keywords | landslide / debris flow / groundwater / initiation mechanism / motion mechanism / field investigation / ring shear tests / grain crushing / 地下水浸透 / 運動シミュレーション / 変形解析 / 地質構造 / 安定評価 / 風化作用 / 砂岩・泥岩互層 / 運動予測 / ハザード・マップ |
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| Research Abstract |
The Jinnosuke-dani landslide is a giant landslide 2,000 m long and 500 m wide in the Haku-san Mountain area, Japan. It was also the first landslide to be designated as a "Landslide Prevention Area" according to the "Japan Landslide Prevention Law". This landslide consists of alternating layers of sandstone and shale in the Tedori Formation, which was deposited from the Jurassic period to the Early Cretaceous. Based on deformation monitoring results for more than 7 years, the landslide is divided into upper and lower blocks. The upper block has moved at a speed of 80 to 170 mm/year, while the lower block has moved more slowly (3 to 15 mm/year). Monitoring data show that the variation of the groundwater level has a great influence on the landslide movement. The deteriorating effect of the weathering of the alternating layers of sandstone and shale on the landslide deformation has been confirmed by borehole exploration and monitoring.
Concerning the landslide motion prediction when a giant
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potential landslide occurs, a prediction program for landslide motion was developed and improved. Through a back-analysis on the Bettou Failure occurred in 1934, the parameter of landslide during motion was obtained, and then used in the motion prediction on the Jinnosuke-dani landslide. The result shows that it is with high risk for the sliding mass rushes into the Tedori-gawa dam reservoir, and shows the high necessity of early -warning.
In May 2004, a landslide occurred at the right flank of the Jinnosuke-dani landslide ; this slide was transformed into a debris flow after fluidization. By analysis of the monitored video images of the debris flow, field investigation of the source area of the landslide, and a series of simulation tests with a ring-shear apparatus on the initiation of the rainfall-induced landslide and its traveling process, the initiation and traveling mechanisms of the debris flow traveling in the valley were investigated. It is shown that concentrated groundwater flow was the main reason for the landslide initiation, and a rapid decrease of the mobilized shear resistance even under naturally drained condition caused the rapid landslide motion. During the debris motion in the valley, high potential for grain-crushing of deposits in upstream and lower potential for the downstream deposits controlled the traveling and stopping process. Different grain-crushing potential of the valley deposit played an important role in the debris flow traveling and stopping processes. Less
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