1992 Fiscal Year Final Research Report Summary
Rock Stress Measurement by Means of Conical-ended Borehole
| Project/Area Number |
03555136
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
資源開発工学
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| Research Institution | Kumamoto University |
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Principal Investigator |
SUGAWARA Katsuhiko Kumamoto University, FAculty of Engineering, Professor., 工学部, 教授 (60109668)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAYAMA Tomoharu Kumamoto University, Faculty of Engineering, Research Associate., 工学部, 助手 (70207950)
OBARA Yuzo Kumamoto University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (50135315)
KANEKO Katsuhiko Kumamoto University, Faculty of Engineering, Associate Professor., 工学部, 助教授 (20128268)
OMI Michito Kumamoto University, Faculty of Engineering, Professor, 工学部, 教授 (30040405)
OKAMURA Hiroshi Kumamoto University, Faculty of Engineering, Professor., 工学部, 教授 (40040373)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Rock Stress Measurement / Stress Relief Method / Conical-ended borehole Technique / Accuracy of Rock Stress Determination |
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| Research Abstract |
Rock stress is of fundamental importance for the construction of rock structures, such as underground openings, since the mechanical behavior of surrounding rock masses is mainly dominated by rock stress. Therefore, the rock stress measurement is considered to be an important field measurement in rock engineering. Particularly, recent developments in relation to the prediction of structural stability of underground openings have indicated th e need for systematic stress measurement, e.g. the systematic initial stress measurement.
In order to determine the complete state of stress at a certain point within a rock mass, the conical-ended borehole technique is proposed to measure the three dimensional state of stress in a rock mass with a high accuracy and low costs by the stress relief method, and the optimum shape of the bottom surface is discussed as well as the gauge arrangement. It is shown how the stress tensor can be determined from the strains on the conical bottom surface of a single borehole, and how the error of stress determined can be evaluated theoretically. The sensitivity and the practicality of the present method are discussed, comparing the conventional methods of in situ stress measurement. Subsequently, by examining the stress distribution obtained by the multiple times stress measurement in a single borehole, it is discussed that the uniformity and the continuity of the field stress are frequently injured by the presence of the geological discontinuities like faults.
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