1999 Fiscal Year Final Research Report Summary
Experimental study on liquefaction strength of well-graded gravelly soil
| Project/Area Number |
09450184
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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 | Chuo University |
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Principal Investigator |
KOKUSHOU Takaji Chuo University, Faculty of Science and Engineering, Professor, 理工学部, 教授 (80286955)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Gravelly soils / Liquefaction / Grain size distribution / unifomity coefficient / Triaxial test / Membrane penetration effect / Masa soil / Fines content |
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| Research Abstract |
Liquefaction in gravelly soils and their significant damages have been increasingly witnessed in recent earthquakes. In this experimental research, liquefaction strength of gravelly soils have been intensively studied in relation with grain size distribution, density, grain crushability, etc. Cyclic loading tests as well as post-liquefaction monotonic loading test in undrained condition carried out for soils with different particle distributions by means of a middle-size triaxial apparatus give following major findings;
1) Despite a large difference in absolute density, liquefaction strength can be uniquely determined by the relative density, Dr, of gravelly soils.
2) By combining previously proposed SPT N-value versus Dr relationship with the above finding, it is concluded that the liquefaction strength is smaller in gravelly soils than in sandy soils if both have the same N-value.
3) For post-liquefaction undrained shear strength for larger strain range, soils with high gravel content tends to enormously dilate and give much higher strength even for the same relative density.
4) Masa soil (Decomposed granite soil) shows weaker liquefaction strength because it contains a large amount of fines and its soil particles tend to crush easily.
5) Reconstituted Masa soil having the same particle size distribution as the gravelly soil gives smaller liquefaction strength and smaller undrained strength including flow behavior, indicating high crushability of the soil grain.
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