1987 Fiscal Year Final Research Report Summary
Constitutive Equation of Sands under Cyclic Loading and its application to Seismic Response Analyses
| Project/Area Number |
60460213
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
農業土木
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| Research Institution | Meiji University |
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Principal Investigator |
TANAKA Tadatsugu Faculty of Agriculture, Meiji University, Associate Professor, 農学部, 助教授 (70167500)
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| Co-Investigator(Kenkyū-buntansha) |
SANO Fumihiko Faculty of Agriculture, Meiji University, Professor, 農学部, 教授 (20007652)
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| Project Period (FY) |
1985 – 1987
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| Keywords | Pore Pressure / Liquefaction / Finite Element Method / Elasto-plasticity / 動的応答解析 |
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| Research Abstract |
1, During an earthquake, the effective stress in water saturated soil structures often decreases. Consequently, these soils eventually liquefy due to the increase in the pore water pressure. The permanent volume contraction (densification) of soils is responsible for the increase in pore water pressure. The densification of the soils under irregular strain history is expressed by applying the endochronic formulation. In order to evaluate the validity of the analytical procedure for liquefaction, undrained cyclic triaxial tests were performed, and the results were compared with those of analyses using endochronic parameters obtained from simple shear tests. The results on pore water pressure predicted by the liquefaction analysis agreed well with those obtained from experiments. In the analyses, the calculated increment of pore water pressure was influenced by the values of the elastic modulus. 2. A numerical procedure for predicting the collapse loads of soil structures is presented using dynamic relaxation with linear isoparametric elements and the one-point integration procedure. The elasto plastic problems such as strip footings and slopes were analyzed and the collapse loads were success- fuily obtained for non-associated folw rules and soil with high friction angles. The constitutivr model employed is based on the yield criterion of Mohr-Coulomb and the plastic potential of Drucker-Prager. 3. In 198o, many small earth dams for irrigation were damaged by the Mid Japan-sea Earthquake.An earth dam destroyed due to liquefaction was investigated and analyzed. The analytical results gave a reasonable estimation for the actual liquefaction behavior of the dam.
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