| Project/Area Number |
21K04264
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 22030:Geotechnical engineering-related
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| Research Institution | Shizuoka Institute of Science and Technology |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
河又 洋介 国立研究開発法人防災科学技術研究所, 地震減災実験研究部門, 主任研究員 (90740994)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Project Status |
Completed (Fiscal Year 2023)
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| Budget Amount *help |
¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2023: ¥390,000 (Direct Cost: ¥300,000、Indirect Cost: ¥90,000)
Fiscal Year 2022: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2021: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
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| Keywords | 液状化 / 過剰間隙水圧 / せん断剛性 / S波速度 / 体積ひずみ / 現地調査 / せん断波速度 / 沈下 |
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| Outline of Research at the Start |
一般に，液状化が発生すると過剰間隙水圧発生により地盤の強度や剛性が消失し，その後，過剰間隙水圧消散とともに地盤性状は回復すると考えられる．しかし，実際には，過剰間隙水圧の消散をは同期せずに，液状化後における地盤性状の回復遅れが幾つか報告されている．
そこで本研究では，室内レベルで非破壊試験および小型のサウンディングによる微視的な構造変化メカニズムを把握し，また，熊本地震時の液状化被害サイトの調査を行い，室内試験結果から，現場における長期的な地盤性状回復過程の説明を試みる．
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| Outline of Final Research Achievements |
It has been reported that the recovery of soil properties after liquefaction is not always synchronized with the dissipation of excess pore water pressure. The purpose of this study is to clarify the microscopic mechanism of delayed recovery of soil properties after liquefaction based on field investigations. The results obtained from the geotechnical investigations indicate that the recovery of soil properties is not synchronized even during the dissipation process of excess pore water pressure during liquefaction, and that the possibility of liquefaction gradually decreases after the earthquake compared to the pre-liquefaction condition. On the other hand, in the laboratory experiments, the shear elastic wave velocity and shear stiffness recovery after the dissipation of excess pore water pressure were confirmed, although the data varied widely, and the results obtained from the laboratory experiments were found to explain the field investigation results.
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| Academic Significance and Societal Importance of the Research Achievements |
一般には，地震時に地盤の液状化が発生すると，過剰間隙水圧の発生により地盤の強度や剛性が消失し，その後，排水に伴う過剰間隙水圧の消散とともに地盤性状は回復する，所謂，圧密理論に準じた挙動と考えられることが多い．しかし，本研究成果では，液状化後，しばらくたってから地盤性状が回復してくることを，現地調査結果と非破壊試験として模型地盤におけるせん断波速度の時系列の変化で示すことが出来た．地震後の避難ルートや，復旧計画などに地震後のタイミング次第では，大きく影響する可能性があり得ることが本研究の学術的・社会的意義が大きい部分と考える．
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