2019 Fiscal Year Final Research Report
Development of the prevention technology of the permeable deterioration in frozen ground, non-frozen ground border of the frozen ground method water shielding wall
| Project/Area Number |
17H03307
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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 |
Geotechnical engineering
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| Research Institution | Setsunan University |
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Principal Investigator |
Ito Yuzuru 摂南大学, 理工学部, 教授 (30281752)
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| Co-Investigator(Kenkyū-buntansha) |
所 哲也 北海学園大学, 工学部, 准教授 (40610457)
石川 達也 北海道大学, 公共政策学連携研究部, 教授 (60359479)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Keywords | 凍土 / 未凍土 / 遮水 / 透水係数 / 凍結融解土 / モデル実験 |
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| Outline of Final Research Achievements |
The frozen earth wall of the Fukushima Nuclear Power Plant prevents an inflow of the groundwater to the nuclear reactor building and prevents increase of the contaminated water.It is assumed that the earth wall is maintained for a long term. Then a horizontal shrinkage crack by de-hydration due to frost heave occurs in front of the ice lens, and it was assumed that the extremely great increase in hydraulic conductivity might generate in front of the frozen earth wall.
To confirm this hypothesis and to propose the preventive measure to this phenomenon, we developed the experimental device which could freeze-thaw the specimen horizontally and conduct permeability test vertically. The test result shows that even if a frost front remained at the constant position, a change of the void structure continued with time regardless of the frost-susceptibility of the fine-grained soil, and it was considered that the possibility that water shield of the earth wall was spoiled may be increasing.
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| Free Research Field |
地盤工学
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| Academic Significance and Societal Importance of the Research Achievements |
福島原発の凍土遮水壁は現在安定しているので、事業者は凍土壁が所定の規模に成長した後は問題がないものと信じているようである。しかし、常温の地盤に構築されて長期間維持される人工凍土の研究事例は極めて少なく、ましてや隣接する未凍土に及ぼす影響が明らかになっているとは言えない。
本研究では、凍土の前面で脱水作用を受け続ける未凍土における脱水による構造変化とそれに伴う遮水性の喪失現象を解明するものであり、その成果は凍土遮水壁の安全性に関わり社会的な意義は大きい。
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