| Project/Area Number |
18K04332
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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 | Kanto Gakuin University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
梶田 幸秀 九州大学, 工学研究院, 准教授 (10403940)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2020: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2019: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2018: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
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| Keywords | 複数回連続強震 / 載荷パターン / 入力強度 / 入力順序 / 耐力低下 / 橋台アプローチ部 / 液状化 / 沈下 / 橋台背面アプローチ / 過剰間隙水圧 / 鋼製橋脚 / 地震時耐荷性状 / 段差量（沈下量） / 耐力劣化 / 段差量 / 使用性リスク / 車両通行性 / 橋台アプローチ / 進行性破壊 |
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| Outline of Final Research Achievements |
We investigated the progress of subsidence due to liquefaction of the abutment approach and the repeated decrease in the bearing capacity of steel piers. As a result of the examination, the amount of subsidence of the abutment approach and the response displacement of the pile increase due to multiple strong earthquakes with the same input strength. However, if the input after the mainshock had a measured seismic intensity of about 3, it was found that the drainage compacted the ground after the mainshock, and the amount of subsidence of the abutment rear approach part was almost unchanged. It was also confirmed that the maximum yield strength of steel piers decreases as local buckling progresses due to multiple strong earthquakes.
It was clarified that the damage would be expanded by multiple strong earthquakes of the same scale as the mainshock, and that the damage, in that case, would be smaller than the simple sum of damage prediction by the ground motion alone.
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| Academic Significance and Societal Importance of the Research Achievements |
2016年熊本地震では設計地震動（レベル2）相当と考えられる震度6弱以上がKiK-net益城観測点で約28時間内に5回も観測された。通常の設計では，原則として強震動にさらされるのは1回としている。この事象に対し，設計上どのように考慮すべきかに関して知見を得ることは重要な課題である。この課題に対して，橋台アプローチ部の液状化による沈下量の進展や鋼製橋脚の繰り返しによる最大耐力の低下の影響を把握したことは今後の耐震設計法を整備するうえで学術的にも意義ある成果である。
また，複数回連続強震による橋台アプローチ部の沈下量を適切に評価することは地震後の早期復旧に資すると考えられ社会的意義も大きい。
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