1998 Fiscal Year Final Research Report Summary
Development of Stress Measurement Method for Rock Mass under Severe Condition
| Project/Area Number |
08555252
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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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 | HOKKAIDO UNIVERSITY |
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Principal Investigator |
ISHIJIMA Yoji Graduate School of Engineering, Hokkaido University, Prof., 大学院・工学研究科, 教授 (10011115)
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| Co-Investigator(Kenkyū-buntansha) |
KIKUCHI Shinji JDC Section Chief, 課長
NAKAMURA Akira Graduate School of Engineering, Hokkaido University, Res.Assoc., 大学院・工学研究科, 助手 (60125333)
FUJII Yoshiaki Graduate School of Engineering, Hokkaido University, Assoc.Prof., 大学院・工学研究科, 助教授 (70192309)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Borehole Wall Deformation / Change in Borehole Diameter / Axial Strain / Shear Displacement / Coefficient of Sensitivity / Built-in Data Logger / Soft Rock / High Stress Zone |
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| Research Abstract |
In-situ stress measurement is usually cost and time-consuming and can be carried out for rock mass under limited good conditions. The chief investigator developed the theory of the borehole wall deformation method 25 years ago in order to make the measurement simple and to extend the applicable fields. The technology innovation in the measurement field enabled us to develop the stress probes for the borehole deformation method. The main results of the investigation are as follows :
(1) The theory was re-examined and it was recognized that the calculation errors can be easily estimated and the probe can be used for rock mass that shows creep behavior since the observation equations are very simple ;
(2) Two types of probe were developed. One measures the change in borehole diameter in three directions and the axial strain. Another measures the shear deformation in the two planes which are parallel to the axial direction. The three dimensional stress state can be determined by using these two probes in one borehole ;
(3) The probes are mechanically tough and waterproof so that they are easily set at desired depth in a borehole even if is filled by water. The measurement can be carried out as soon as the probe is set with no waiting ;
(4) A small built-in data logger was developed. It enabled us to eliminate the cable between the probe and the measurement system out the borehole. This made the possibility of troubles such as cable jamming etc. much less and deeper measurements enable ; and,
(5) Stresses at a down hole in soft rock mass, uniaxial compressive strength of rock specimens is between 0.02 and 0.08 MPa, and at a high stress zone, where disking was observed, were successfully measured. This implies that the developed measurement method is suitable for the severe conditions.
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Research Products
(2 results)
