2023 Fiscal Year Final Research Report
Pull-out tests of piles leading to the development and verification of tsunami-resistant reinforcement methods for coastal mid-rise buildings by ground improvement
| Project/Area Number |
21K04245
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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 22020:Structure engineering and earthquake engineering-related
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| Research Institution | National Research Institute for Earth Science and Disaster Prevention |
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Principal Investigator |
Kawamata Yohsuke 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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| Co-Investigator(Kenkyū-buntansha) |
中澤 博志 静岡理工科大学, 理工学部, 教授 (20328561)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | 杭の引抜き抵抗 / 液状化 / 津波耐力 |
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| Outline of Final Research Achievements |
In the 2011 off the Pacific coast of Tohoku Earthquake, it was reported that some buildings were overturned due to pile pull-out by the tsunami. Therefore, it is important to evaluate the pile pull-out resistance during tsunami attack and to reinforce the piles as necessary.
In this study, small model experiments were conducted to evaluate the pile pullout resistance during the pore water pressure buildup, full liquefaction, and after the pore water pressure dissipation.
Based on the experimental results, it was clarified that the pile pullout resistance does not decrease until the pore water pressure increases to some extent, that the pile pullout resistance decreases only to about half of the pre-earthquake level even under full liquefaction, and that the pile pullout resistance does not return to the pre-earthquake level even if the pore water pressure completely dissipates. These results are different from the conventional view and suggest the need for further research.
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| Free Research Field |
地盤工学
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| Academic Significance and Societal Importance of the Research Achievements |
沿岸部の津波避難ビルが，地震により液状化する恐れのある地域に立地していることは珍しくない。地震発生後，数分から数十分以内に津波が襲来するため，地盤中の間隙水圧が残留している状態もしくは消散して間もない状態である可能性が高い。また，余震の影響で，津波襲来時に完全液状化状態にあることも考えられる。そのため，間隙水圧の上昇過程～完全液状化～間隙水圧消散後の各段階における，杭の引抜き抵抗を評価することにより，実際に津波が襲来したタイミングでの建物の津波耐力を推定することが不可欠となる。このような研究はこれまでにないものであり，本研究はその第一歩となりうるものである。
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