1995 Fiscal Year Final Research Report Summary
Evaluation of Mechanical Characteristics during Long Period of Artificial Geo-material under Deep Underground Condition
| Project/Area Number |
06650544
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Geotechnical engineering
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| Research Institution | Yamaguchi University |
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Principal Investigator |
MURATA Hidekazu Yamaguchi University, Faculty of engineering, Professor, 工学部, 教授 (80044618)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAMOTO Tetsuro Yamaguchi University, Faculty of engineering, Associate Professor, 工学部, 助教授 (10035074)
MATSUDA Hiroshi Yamaguchi University, Faculty of engineering, Associate Professor, 工学部, 助教授 (50136131)
HYODO Masayuki Yamaguchi University, Faculty of engineering, Associate Professor, 工学部, 助教授 (40130091)
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| Project Period (FY) |
1994 – 1995
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| Keywords | artificial geo-material / unsaturated soil / stress strain behavior / triaxial compression / constitutive equations / suction |
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| Research Abstract |
In the underground disposal for relatively high radioactive wastes, bentonite and sand mixtures are expected to be used as a buffer material which acts as a low permeable layrs. Buffer layrs and walls surrounding concrete silo will be constructed by compacting bentonite and sand mixtures at the silo type repository. To assess the structural stability of repository component, it is necessary to predict the mechanical behavior of the buffer zone. However the mechanical behavior of the bentonite and sand mixtures was not apparenet at the beginning of this study. Thus studies to determine the mechanical properties of bentonite and sand mixtures were initiated to assist in developing a numerical model and in determining the experimental parameters for numerical analysis. A series of triaxial compression tests of the mixtures was performed. It was found that the mechanical properties of the bentonite and sand mixtures are strongly influenced by water and bentonite contents : shear strength in a saturated state is less than that in an optimum water content state ; shear strength decreases rapidly with increasing bentonite content. Strength properties are much dependent on the confining pressure. In addition, the suction controlled tests had been carried out to investigate the effect of suction on the mechanical behavior of bentonite-sand mixtures. The following results could be obtained : (1) The stiffness of the mixtures increases with increasing suction. (2) The volumetric strain and water drainage increase on suction loading. The reduction in suction induces a volumetric compression (collapse). (3) The shear strength of the mixtures increases with increasing suction. The failure envelopes show that the cohesion of the mixtures increases with increasing suction while maintaining a constant friction angle.
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Research Products
(2 results)
