1998 Fiscal Year Final Research Report Summary
Study on rolling motion mechanism of a rockfall on slope of weak ground
| Project/Area Number |
08650579
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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 |
Geotechnical engineering
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| Research Institution | Ehime University |
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Principal Investigator |
MURO Tatsuro Ehime University, Faculty of Engineeriong, Professor, 工学部, 教授 (00025967)
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| Co-Investigator(Kenkyū-buntansha) |
KAWAHARA Soichiro Ehime University, Faculty of Engineeriong, Research Assistant, 工学部, 助手 (50169752)
FUKAGAWA Ryoichi Ritsumeikan University, Faculty of Science and Engineering, Professor, 理工学部, 教授 (20127129)
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| Project Period (FY) |
1996 – 1998
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| Keywords | rockfall / line motion / model test / soil slope / slope gradient / ratio of residual velocity to free fall / slip ratio / energy consumption |
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| Research Abstract |
The objective of the present research is to investigate the line-motion constants and the energy consumption of rockfalls in consideration of the sinkage. A series of laboratory experiments was executed in the combination of rockfall masses and slope gradients on a flat homogeneous slope made of Toyoura standard sand. The apparatus consisted of three main parts : a rockfall model, a soil bin arid a crane. The rockfall models made of steel and aluminum were columns having a diameter of 7.5, 10.0 and 12.5 cm and a width of 9.0 cm. The soil bin filled with the compacted soil had an effective length of 230 cm, a width of 30 cm and an effective depth of 25 cm. The rockfall models were dropped on the soil slope of the gradients ranging from 15 through 35 degrees.
As a result, the conclusions are summarized as follows.
1) The motion of the rockfall is uniform acceleration.
2) Both the acceleration of the rockfall and the ratio of the residual velocity to free fall increase linearly with the slope gradient.
3) Both the acceleration of the rockfall and the ratio of the residual velocity to free fall decrease with the rockfall mass on the soil slope because the motion resistance increases with the sinkage.
4) Both the slip ratio in braking state and the kinetic energy ratio of the rotation to the translation decrease with thc slope gradient arid the rockfall mass.
5) The ratios of the soil compaction energy to the potential increases considerably with the rockfall mass because the ratios of the kinetic energies to the potential decrease considerably.
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