| Project/Area Number |
16H04402
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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 |
Structural engineering/Earthquake engineering/Maintenance management engineering
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| Research Institution | Hosei University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
子田 康弘 日本大学, 工学部, 准教授 (40328696)
仙頭 紀明 日本大学, 工学部, 准教授 (40333835)
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥18,850,000 (Direct Cost: ¥14,500,000、Indirect Cost: ¥4,350,000)
Fiscal Year 2018: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2017: ¥7,930,000 (Direct Cost: ¥6,100,000、Indirect Cost: ¥1,830,000)
Fiscal Year 2016: ¥6,890,000 (Direct Cost: ¥5,300,000、Indirect Cost: ¥1,590,000)
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| Keywords | 繰返し荷重 / 砂利化 / コンクリート / 水圧 / ひび割れ / 床版 / 粗骨材 / 砂利化指数 / 疲労 / 液状化 / せん断 / 細孔構造 |
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| Outline of Final Research Achievements |
This study aims to identify a specific degradation of concrete which has been observed on bridge decks made of reinforced concrete (RC). Compressive load and external water pressure were cyclically applied to submerged concrete cylinder specimens with different pre-loading and restraint conditions. Then, fine aggregates without cement matrix were found on inner surfaces of split specimens. These phenomena were quantitatively analysed and the analyses suggested that cyclic water pressure acted to inside of pre-cracked specimens and washed out their cement matrix to outside. Degradation of rough crack surface was also examined by cyclic shear test with/without water supply to the crack. The shear slip and the orthogonal displacement were clearly amplified with increase of the cycle when the water was supplied. The mechanical properties of cracked concrete with water in shear were discussed in accordance with that of liquefaction.
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| Academic Significance and Societal Importance of the Research Achievements |
湿潤状態で繰返し作用をうける我が国の道路橋鉄筋コンクリート床版で多くみられるコンクリートの「砂利化」と言われる現象について，その原因のひとつがコンクリート細孔中の凝縮水の水圧上昇によるコンクリート骨格の破壊であるという仮説を，実験と理論から検証した．水圧やコンクリート中の粗骨材等の条件をパラメータとした要素実験（水圧，圧縮，せん断）では，砂利化現象の初期の兆候をとらえることに成功し，これをもとに，「砂利化指数」を提案した．また，FEMにおいても，本指数は損傷を定性的に示すことを確認した．定量的な評価値に改善の余地はあるものの，簡易な指標で砂利化の度合いを評価する手法の提案は，社会的意義がある．
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