| Project/Area Number |
05650964
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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 | 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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| Co-Investigator(Kenkyū-buntansha) |
KUBOTA Satoshi Yatsushiro National College of Technology. Associate Professor, 助教授 (00132671)
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| Project Period (FY) |
1993 – 1994
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1994: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1993: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Stress waves / Shock waves / Blasting phenomena / Laser shadowgraphy / Controlled crack / Guide hole techniues / レーザー干渉法 / シャドウグラフ法 / き裂進展 / ガイドキ-ル / 空気中衝撃波 / 動ひずみ / ガイドホール / フォトメカニクス |
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| Research Abstract |
Dynamic fracture control in blasting is very important in underground excavation and demolition of concrete structures. It is necessary to examine the dynamic mechanism of stress waves, gases and cracks in blasting process for achieving high degree of fracture control. In this research, experimental results on visualization of stress waves in blasting by a laser-shadowgraph method are presented and a new method for fracture controlled blasting is suggested. The shadowgraph system using a Q switched ruby laser as a light source is set up. The system enables us to get a giant pulse beam at a desired time and to obtain the high spatial and time resolved instantaneous visualization photographs.
Experiments are made on stress waves interacting with a circular hole, a circular arc-shaped free surface and a free surface with 90ﾟ corner. Model experiments are casrried out with the PMMA plate of 20 mm in thickness as a transparent material. From these experiments, the following results are obtained. The shadowgraphs show the behavior of reflected waves, deformations of the circular hole and the generation of converging shock waves in the hole by interaction of incident waves with the hole. In the case of the hole with two notches along the prpagation direction of the incident waves, it can be seen that the well-known shadow spots are produced in the vicinity of the notches. From the fact, it might be expected that utilization of the circular hole with notches is effective as the guide hole technique for achieving fracture control.
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