| Project/Area Number |
16404011
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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 | 海外学術 |
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| Research Field |
Geotechnical engineering
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
JIRO Takemura Tokyo Institute of Technology, Faculty of Eng, Acco. Prof (40179669)
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| Co-Investigator(Kenkyū-buntansha) |
OHTA Heideki Tokyo Inst. of Tech., Faculty of Eng, Professor (80026187)
KUSAKABE Osamu Tokyo Inst. of Tech., Faculty of Eng, Professor (40092548)
IZAWA Jun Tokyo Inst. of Tech., Faculty of Eng, Research Associate (70345388)
WATABE Yoichi Port and Airport Research Institute, Soil Mechanics Lab, Head (00371758)
TANAKA Masanori Port and Airport Research Institute, Soil Mechanics Lab, Chief Researcher (20371768)
桑野 二郎 東京工業大学, 大学院・理工学研究科, 助教授 (30178149)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥13,400,000 (Direct Cost: ¥13,400,000)
Fiscal Year 2006: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 2005: ¥5,000,000 (Direct Cost: ¥5,000,000)
Fiscal Year 2004: ¥6,300,000 (Direct Cost: ¥6,300,000)
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| Keywords | Delta / Alluvial deposit / Sampling / Disturbance / Field tests / Laboratory tests / Compressibility / Strength / 軟弱地盤 / 粘土 |
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| Research Abstract |
In this study collaboration researches about the soil characterization on the alluvial deposits at the Tan An and Can Tho sites in Mekong River Delta, South Vietnam. The following conclusions were drawn from the study.
(1) The Tan An clay, which has been deposited at the riverside of meandering Bam Co Tay River, is highly plastic and very soft with relatively uniform physical properties to a depth of about 8m.
(2) The Can Tho soft clay has been deposited at the flooding area beside the levee of Hau River, one of the major streams of Mekong River. It has significant heterogeneity in the depositional direction, having relatively low plasticity with thin sand seams, which might be created due to large floods.
(3) Depositional speed of the Can To clay is much faster than that of the Tan An clay. C14 dating of the Tan An clay at depth of 6.5m and the Can Tho clay at depth of 19.5m are almost the same, 6,300BP.
(4) Although mechanical and physical properties of the two clays are quite different,
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both clays have developed high degree of microstructures, which has been confirmed from CRS tests. The ratios of maximum compression index just after the consolidation yield stress to that at the very large consolidation pressure are more than 6 for both clays if excellent quality of sample can be retrieved.
(5) For the non uniform and very thick soft deposit like the Can Tho clay, continuous soil sounding using piezocone is essential for characterizing the site.
(6) Sampling method has significant effect on the sample quality especially for low plastic clay, like Can Tho. JFP is much more superior to Shelby. However, for high plastic clay, the sample collected by Shelby tube sampler might give similar quality to those collected by FFP.
(7) Beside the above mentioned sampling method, there are some problems in the process of soil investigation in Vietnam, such as poor handling of the samples from the site to laboratory and specimen preparation in the laboratory.
(8) Wide varieties of soft soils with different physical and chemical properties prevail in the huge area of Mekong River Delta. Continuous soil investigation studies and practices with good quality sampling, such as thin-walled tube sampler with fixed piston, and laboratory testing as well as appropriate field testing are highly recommended, which can greatly contribute to the proper development in Mekong River Delta. Less
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