| Project/Area Number |
07309016
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
広領域
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| Research Institution | NATIONAL INSTITUTE FOR ENVIRONMENTAL SUTDIES |
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Principal Investigator |
TOHNO Ikuo National Institute for Environmental Studies, Water and Soil Environment, Geotechnical Engineering, Leader, 水土壌圏環境部, 室長 (00016479)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Masaaki Dohto University, Junior College, Civil Engineering, Associate Professor, 短期大学部, 助教授 (30226550)
YASUHARA Kasuya Ibaraki University, Engineering, Urban and Civil Engineering, Professor, 工学部, 教授 (20069826)
ENDO Kunihiko Nihon University, Humanities and Sciences, Geosystem Sciences, Professor, 文理学部, 教授 (70059781)
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| Project Period (FY) |
1995 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥7,400,000 (Direct Cost: ¥7,400,000)
Fiscal Year 1997: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1996: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1995: ¥4,700,000 (Direct Cost: ¥4,700,000)
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| Keywords | LIQUEFACTION / SAND LAYER / SEDIMENTARY STRUCTURE / MECHANICDAL PROPERTY / TOPOGRAPHICAL ANALYSIS / TEXTURE / DENSITY / TEST PIT / 粒度組成 / 土質試験 |
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| Research Abstract |
Change in sedimentary structure and/or disturbance caused by liquefaction was investigated in the test pits of liquefied sand or gravel layrs, occured during the 1993 Hokkaido-Nansei-Oki (Southwest off Hokkaido) earthquake and 1995 Hyogo-Ken-Nanbu (South Hyogo prefecture) earthquake.
(1) Liquefied sand dikes caused by Hokkaido-Nansei-Oki earthquake found in sandy silt layr of 1.5-2.0 m in thickness, were intruded from the underlying sand and gravel layr, including about 50% gravel-fraction.
Lower part of the sand dikes is composed mainly of gravel, and flat ones tend to be turned nearly vertically. In the mid part of sand dikes, the amount of gravel decreasing, and in the upper part sand-sized fraction dominated. The liquefied layr is fluvial sand and gravel in the latest Holocene.
(2) The liquefaction site distribution map was drew up after the Hyogo-Ken-Nanbu earthquake from Osaka bay area to Awaji Island and Naruto city.
In the reclaimed land, liquefied layrs are the filled materials of weathered granite soil in Kobe. Matrix part among coarse granite blocks in the liquefied layr might be liquefied during the earthquake. Grain-size of liquefied materials in the sand dikes changes from coarse-grained and not well-sorted in the lower part, and fine-grained and well-sorted in the upper.
(3) Result of cyclic triaxial compression tests, the change of strength ratio with excess pore water pressure during the cyclic loading was caused very little by the difference of initial structure of specimens taken from sand sample, but the volume change after liquefaction had influence on their specimens.
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