1998 Fiscal Year Final Research Report Summary
On Application of a Caisson with Suction to Breakwater Structure
| Project/Area Number |
09650558
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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 | Maizuru National College of Technology |
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Principal Investigator |
TAKATANI Tomiya Maizuru National College of Technology Civil Engineering Associate Professor, 建設システム工学科, 助教授 (70179448)
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| Co-Investigator(Kenkyū-buntansha) |
MAENO Yoshi-hiko Nihon University Civil Engineering and Environment Professor, 教授 (90110139)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Caisson with Suction / Breakwater / Irregular Wave / Pore Water Pressure / Wave Pressure Experiment / Pile Foundation / Dynamic Response Analysis |
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| Research Abstract |
To apply a steel caisson with skirt, which takes suction effect into the stability, to the coastal structure on soft seabed, dynamic responses of the caisson structure with suction and its soft foundation under wave attack were simulated by an advanced caisson structure-seabed interaction analysis. Also, the dynamic response of a caisson-type structure resting on pile foundation loaded by waves was numerically evaluated by FEM analysis in order to investigate the feasibility of a pile with an expanding end to support such offshore structure foundations.
The results obtained in this research is summarized as follows :
1) The displacement response at an estimating location under a caisson structure becomes small and the phase angle is large as the non-dimensional frequency wa/Vs and the depth z/a of an estimating location increases. Consequently, the displacement response of seabed under a caisson structure greatly depends on the skirt length of a caisson structure as seen in the displacement response of a caisson itself.
2) It is necessary to give careful consideration to the behavior of both the displacement and phase responses in case of installing a caisson structure with suction on the seabed, whose stiffness and shear wave velocity are small.
3) The dynamic response of pore water pressure under caisson has a maximum value in the vicinity of compartments, and also gradually decreases with the distance from the bottom of caisson increasing.
4) When a caisson is installed on a pile foundation, the displacement response in the seabed around the pile foundation, as well as that of the caisson, are almost similar regardless of the connecting condition between caisson and piles.
5) The pile foundation prevents the differential settlement in the seabed under a caisson, because the wave-induced pore water pressure beneath the caisson is distributed to the deep foundation around the expanding base.
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