DEVELOPMENT OF EVALUATION METHOD FOR LIQUEFACTION OF GROUND CONSIDERING DUCTILE NATURE

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Current prediction method of liquefaction issues the alternative conclusion of whether there is no liquefaction damage. However, according to the actual liquefaction damage such as the Great Hanshin Earthquake, it is clear that the damage level continuously changed. This is because load level of the earthquake motion as an external force and the toughness of the ground continuously change. Especially, there is no technique that quantitatively evaluates it on the toughness of the soil in present state. Therefore, we can not distinguish the fracture event between of dense sandy soil in which the rigidity recovers and of the loose sand without ductile nature. The purpose of this study is to develop the technique that can quantitatively evaluate ductile nature of the soil.New strain controlled-test method that could quantitatively evaluate ductility of the soil was proposed in the 1998 fiscal year. Based on this proposed technique, the applicability was examined for various soil composed of sand content and fine-grain fraction except for gravel. The experimental result was studied in plastic strain energy, and it showed becoming an index which shows ductility index of the soil.The evaluation technique of earthquake intensity as an external force in proportion to the strength index proposed in the 1999 fiscal year. That is to say, the prediction procedure of energy amount used for the plastication of the ground was proposed, when some earthquake motion input it.The research result was presented in the 2000 fiscal year. And the result of this study was published in academic journal and international conference of domestic and overseas. In addition, the research report was printed as a grant-in-aids for Scientific Research report, and it was distributed to the researcher of the same field.