Development of Downward Compact Conical-ended Borehole Overcoring Method for In-situ Stress Measurement at Great Depth.
Grant-in-Aid for Scientific Research (B).
|Research Institution||Tohoku University|
坂口 清敏 東北大, 工学(系)研究科, 助手 (50261590)
MATSUKI Koji Tohoku University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (10108475)
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)
|Project Fiscal Year
1997 – 1999
Completed(Fiscal Year 1999)
|Budget Amount *help
¥8,000,000 (Direct Cost : ¥8,000,000)
Fiscal Year 1999 : ¥1,300,000 (Direct Cost : ¥1,300,000)
Fiscal Year 1998 : ¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1997 : ¥4,400,000 (Direct Cost : ¥4,400,000)
|Keywords||Stress relief method / Compact Conical-ended Borehole Overcoring Method / Vertical borehole / Great depth / 応力解放法 / 円錐孔底ひずみ法 / 垂直ボアホール / 入深度 / 大深度 / 深部地圧測定 / 地圧測定|
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.
Research Output (9results)