1992 Fiscal Year Final Research Report Summary
Experimental Studies on Enviromental Deterioration of Shale Specimen and Its Evaluation
| Project/Area Number |
03650510
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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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 | MURORAN INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
GOTO Tatsuhiko MURORAN INSTITUTE OF TECHNOLOGY FACULTY OF ENGINEERING ASSOCIATE PROFESSOR, 工学部, 助教授 (50125374)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Shale / Environmental deterioration / Crack / Creep test / Fatigue test |
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| Research Abstract |
To investigate deterioration mechanism in bad environment and mechanical behavior of shale included in the WAKANABE formation, water injection test,wetting environmental test and mechanical test were carried out and the following results were summarized.
1. This shale has a dark gray and banded structure to parallel in a direction of formation, and changes sensitivily in response to water and wetting condition.
From AE measurement, it was clarified that crack developed to parallel in a direction of formation and from monitoring strain of specimen under the wetting environment, it was obtained that these cracks were formed by tensile stress field. Cracking process under water and wetting condition, can be explained by the existance of clay mineral contained in shale specimens. This clay mineral in the WAKANABE shale is highly developed in the direction of formation.
2. Multistage triaxial test was conducted by using shale specimens cracked fully. As results, it was ciarified that these cracked specimens have anisotropic behavior for compressive strength and strength of specimen having 30ﾟ or 60ﾟ angle between the loading axis and the direction of formation were smaller than 0ﾟ or 90ﾟ angle. However, it was observed that an effect of confinning pressure resulted in increase of strength.
3. Cycle and creep tests were carried out by using air drying specimens and many similur points were recognized between deformation of fatigue process and creep behavior. Fatigue strength decreases gradually with increase of cycle numbers and fracture time of creep increases with decrease of applied stress.
4. These results will be considered to play an important role of design for rock constructions in shale formation.
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