1999 Fiscal Year Final Research Report Summary
Development of Downward Compact Conical-ended Borehole Overcoring Method for In-situ Stress Measurement at Great Depth.
| Project/Area Number |
09555317
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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 | 展開研究 |
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| Research Field |
資源開発工学
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| Research Institution | Tohoku University |
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Principal Investigator |
MATSUKI Koji Tohoku University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (10108475)
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| Co-Investigator(Kenkyū-buntansha) |
OKUMURA Kiyohiko Tohoku University, Graduate School of Engineering, Research Associate, 大学院・工学研究科, 助手 (40177184)
KIYOHASHI Hiroshi Tohoku University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (70005263)
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| Project Period (FY) |
1997 – 1999
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| Keywords | Stress relief method / Compact Conical-ended Borehole Overcoring Method / Vertical borehole / Great depth |
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| Research Abstract |
Knowledge of in-situ stress at great depth is of fundamental importance for geothermal energy extraction and underground disposal of nuclear waste. In order to estimate In-situ stress at great depth with a high accuracy, Downward Compact Conical-ended Borehole Overcoring Method(DCCBO), which is one of stress relief method was developed. DCCBO method is applicable to a mud water-filled vertical/sub-vertical borehole.
Main results obtained in this study are summarized as follows :
1) An adhesive which is applicable lo a water-filled vertical/sub-vertical borehole bottom was selected.
2) Diving-bell type bonding device which is applicable to a water-filled borehole at a depth of 500m was developed.
3) 16-elements conical strain cell for DCCBO which contained nitrogen gas cylinder was developed.
4) The usefulness of the developed 16-elements conical strain cell in the isotropic rock is verified by loading and unloading tests to the cubic specimen with a borehole.
5) The usefulness of the gushing system of nitrogen gas from the tip of 16-elements conical strain cell is verified by laboratory test using a borehole model made of acrylic.
6) Bonding test of 16-elements conical strain cell to a rock specimen under water-filled condition was successful.
7) Specification of a multi-channel data logger for DCCBO was proposed.
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