| Project/Area Number |
07455405
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | HOKKAIDO UNIVERSITY |
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Principal Investigator |
ISHIJIMA Yoji Hokkaido Univ., Grad.School of Eng.Prof., 大学院・工学研究科, 教授 (10011115)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Akira Hokkaido Univ., Grad.School of Eng.Res.Assoc., 大学院・工学研究科, 助手 (60125333)
FUJII Yoshiaki Hokkaido Univ., Grad.School of Eng.Assoc.Prof., 大学院・工学研究科, 助教授 (70192309)
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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 |
¥7,900,000 (Direct Cost: ¥7,900,000)
Fiscal Year 1997: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1996: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1995: ¥6,800,000 (Direct Cost: ¥6,800,000)
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| Keywords | Rock / Crack / Circumferential Strain / P-wave velocity / Replica / き裂 / 同ひずみ / 異方性 / 砂岩の微視的構造 / 花崗岩の微視的構造 / 開口き裂の配向性 / 三軸圧縮試験 / レプリカフィルム |
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| Research Abstract |
Uniaxial compression tests and triaxial compression tests under confining pressure of 5 MPa were carried out on cylindrical specimens of lnada granite, whose axis coincided with rift or grain plane. Load was removed when circumferential strain reached certain values. P-wave velocity of loaded specimens in axial and radial directions was measured. Replicas of sections, whose normal coincided with loading axis, were observed undera microscope.
P-wave velocity in the axial direction for specimens were larger than that for unloaded specimens in uniaxial case. On the other hand, that decresed slightly with triaxial loading. P-wave velocity in the radial directions decreased in the both uniaxial and triaxial cases. That in R-and G-direction was small than that in H-direction. P-wave velocity in the uniaxial case was smaller than that in the triaxial case with reference to circumferential strain value at unloading. They showed similar behaviors with reference to permanent circumferential strain value.
The thin section method with a blue resin and the replica method were used in order to observe cracks. Determination of mineral type with the replica method was difficult. However, preparation of replica is easy and the method enables observation of cracks in opaque minerals.
Crack density was evaluated with the scan-line method. The crack density increased with circumferential strain magnitude at unloading. That in triaxial casa was smaller than that in uniaxial case with reference to circumferential strain value at unloading. On the other hand, they showed similar behaviors with reference to permanent circumferential strain. In the uniaxial case, cracks that oriented to rift or grain plane dominated. Crack directivity was not observed in the triaxial case. P-wave velocity decreased with crack density. Rate of the decrease in the triaxial case was larger than that in the uniaxial case. Effects of measuring direction (wave path and scan line) was not observed.
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