1996 Fiscal Year Final Research Report Summary
A study of long-term strength of rock by using DT-method
| Project/Area Number |
07651147
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
資源開発工学
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| Research Institution | Yamaguchi University |
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Principal Investigator |
SANO Osamu Yamaguchi University, Dept. Civil Engineering, Professor, 工学部, 教授 (20127765)
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| Co-Investigator(Kenkyū-buntansha) |
MIZUTA Yoshiaki Yamaguchi University, Dept. Civil Engineering, Professor, 工学部, 教授 (20107733)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Double Torsion / Stress Corrosion / Long-term strength / Rock |
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| Research Abstract |
This study focussed on a region of very slow rate of the subcritical crack growth which may play an important role in time-dependent fracture around underground openings. The very slow rate can be important when we consider very long term stability and effective shielding of radio active species. The crack growth was measured for almost two years with relaxation method of the double-torsion technique. In such a method, the loading point must be fixed. However, preliminary experiments showed that a hysteresis in a loading/unloading cycle associated with very small temperature variation could be cumulative increase in deflection of the specimen. In this study, the temperature of the loading system and the specimen was kept constant within 0.1 K,by using double chambers system. The subcritical crack is still growing now. The growth rate in March 1996 corresponds to the rate, 1mm/year. When the crack is in a uniform tensile stress filed, the growth rates should accelerate with increasing crack length. In such a condition, the experimental result obtained in this study will be an important measure for discussing long term stability and the effective shield of the underground openings.
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