2003 Fiscal Year Final Research Report Summary
Clarification of fracturing mechanism by expansive cement agent and basic examination far making an alarm unit to predict an accidental discharge using acoustic emission monitoring
| Project/Area Number |
13650986
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
資源開発工学
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| Research Institution | Yamaguchi University |
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Principal Investigator |
ISHIDA Tsuyoshi Yamaguchi University, Faculty of Engineering, Professor, 工学部, 教授 (10232307)
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| Project Period (FY) |
2001 – 2003
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| Keywords | expansive cement agent / acoustic emission / thermal stress / rock mechanics |
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| Research Abstract |
Calcium oxide (CaO)-based expansive cement, also known as "non-explosive demolition agents", has been widely used to fracture massive rocks and concrete structures. To clarify its fracture mechanism, we made an experiment to fracture a mortar specimen of 200 mm and 300 mm cubic by setting calcium oxide-based expansive cement in a 50 mm diameter hole bored in the center of the specimen. AE (acoustic emission) sources clustered in outside of the specimen rather than vicinity of the hole just before macroscopic cracks generated, suggesting that macroscopic cracks originated at the outside of the specimen and then extended inward. Although the expansive pressure causes tensile stress in tangential direction of the hole, the stress is the maximum in the hole wall and decrease in proportion to square of the distance from the hole. On the other hand, thermal stress due to heating of the hole is tensile in the outside of the specimen but it is compressive in the vicinity of the hole. Thus, it could be concluded that thermal stress has large effects in the fracture caused by calcium oxide-based expansive cement, at least, in a rock or concrete block without preexisting crack
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[Publications] Ishida, T., Taguchi, M., Suemune, K, Fukui, H., Mizuta, Y.: "Fracturing mechanism by expansive cement agent deduced from acoustic emission monitoring"Proc.of 2002 ISRM Regional Symposium (3rd Korea-Japan Joint Symposium)on Rock Engineering Problems and Approaches in Underground Construction, Seoul, Korea.. 841-846 (2002)
Description
「研究成果報告書概要(和文)」より
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[Publications] Ishida, T., Taguchi, M., Suemune, K, Fukui, H., Mizuta, Y.: "Fracturing mechanism by expansive cement agent deduced from acoustic emission monitoring"Proc.of 2002 ISRM Regional Symposium (3rd Korea-Japan Joint Symposium) on Rock Engineering Problems and Approaches in Under round Constructs on, Seoul, Korea, July 2002. (2002)
Description
「研究成果報告書概要(欧文)」より
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[Publications] Suemune, K., Ishida, T., Kinoshita, N.and Fukui, H.: "Effect of thermal stress in the fracturing of expansive cement agent in comparison with heater test of rock"Proc.of the 33rd Symposium of Rock Mechanics, Committee of Rock Mechanics, JSCE, Tokyo, January, 2004. (2004)
Description
「研究成果報告書概要(欧文)」より
