| Project/Area Number |
09555323
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | Yatsushiro National College of Technology |
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Principal Investigator |
NAKAMURA Yuichi Yatsushiro National College of Technology Professor, 土木建築工学科, 教授 (00112392)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥5,100,000 (Direct Cost: ¥5,100,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1998: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1997: ¥3,600,000 (Direct Cost: ¥3,600,000)
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| Keywords | High-speed loading / Rock-like materials / Loading rate / Dynamic strength / Dynamic strain / High-speed videography / Crack propagation / 高速度撮影 / 爆薬 / 岩石 / き裂 / 動的破壊実験 |
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| Research Abstract |
Strength, stiffness and brittleness of rock-like materials are affected by the rate of loading. However, there is a lack of date at high rates loading. In this research, a new high-speed loading apparatus driven by explosives was developed. An electric detonator was used as a charge and set in a charge cylinder filled with water. A loading piston of the apparatus was driven by dynamic actions of underwater shock waves and explosion gases. The dynamic fracture experiments were made for rock-lick materials in compression and/or splitting tension. The dynamic load was measured by a quartz load sensor and the dynamic strains were measured by strain gauges. The dynamic fracture processes of the specimens were observed by high-speed videography. The following results are obtained.
(1)The presented high-speed loading apparatus is reusable and applicable to dynamic fracture experiments of rock-like materials. Results show that the loading rate indicated by the loading duration to the maximum load is about 200〜220 MN/s.
(2)Increases in strength of rock-like materials are observed. The dynamic compressive strength is found to be as much as about 85 to 100% greater than the static strength.
(3)High-speed video images show fracture processes of the specimens in compression, such as crack propagation and shearing fracture produced by end boundary conditions. In splitting tension experiments, cracks are initiated near the center of the cylindrical disk specimen.
(4)Fracture propagation of rock-like materials in tension is observed by using the charge holders with two wedge-shaped air cavities. It is obtained from high-speed video images that the fracture propagating from the charge holder towards the free surface collides with the fracture from the free surface and the fracture plane is produced.
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