| Project/Area Number |
17H03302
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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 | Nagaoka University of Technology |
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Principal Investigator |
Toyota Hirofumi 長岡技術科学大学, 工学研究科, 准教授 (90272864)
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| Co-Investigator(Kenkyū-buntansha) |
杉本 光隆 長岡技術科学大学, 工学研究科, 教授 (50196755)
原 忠 高知大学, 教育研究部自然科学系理工学部門, 教授 (80407874)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥16,510,000 (Direct Cost: ¥12,700,000、Indirect Cost: ¥3,810,000)
Fiscal Year 2019: ¥5,460,000 (Direct Cost: ¥4,200,000、Indirect Cost: ¥1,260,000)
Fiscal Year 2018: ¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000)
Fiscal Year 2017: ¥7,540,000 (Direct Cost: ¥5,800,000、Indirect Cost: ¥1,740,000)
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| Keywords | 液状化 / 年代効果 / せん断波速度 / 三軸試験 / 砂質土 / 原位置試験 |
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| Outline of Final Research Achievements |
It has been well known that liquefaction potential of the ground is increased with an increase of construction or sedimentation ages. However, the mechanism of this aging effect on liquefaction has not been elucidated.
To clarify the mechanism of aging effect in sand, liquefaction resistance, secant shear modulus including G0 and penetration resistance of long-term consolidated sand were respectively measured using undrained cyclic triaxial test, local small strain (LSS) test, bender element (BE) test and static penetration test. Liquefaction resistances obtained from the triaxial test and the static penetration test were respectively increased by about 15% and 7% in one year consolidated specimen. However, G0 was scarcely changed with the consolidation time. The difference is that elastic strain region, where linear elastic behavior was exhibited, tend to extend to larger strain for long-term consolidated specimen.
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| Academic Significance and Societal Importance of the Research Achievements |
液状化抵抗が圧密時間とともに増加するメカニズムについて，力学特性の変化に着目して研究を行った．その結果，初期せん断剛性率や貫入抵抗（せん断強さと関係）についての変化は小さく，主に線形弾性を示すひずみ領域が拡大することによって，液状化抵抗が増加することを明らかにした．つまり，実際の地盤の年代効果を考慮した液状化抵抗の変化を評価するためには，地盤のせん断弾性波や貫入抵抗値を測定するだけでは不十分で，弾性ひずみ領域の拡大を推定する必要がある．しかしながら，これは難しいため，初期せん断剛性率ではなく，ダイラトメータ等により，もう少しひずみの大きいところの割線せん断剛性率を測定する方法が推奨される．
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