1996 Fiscal Year Final Research Report Summary
Response Characteristics of Seabed Around an Offshore Foundation Structure Subjected to Suction Force
| Project/Area Number |
07650584
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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 College of Technology Civil Engineering Associate Professor, 建設システム工学科, 助教授 (70179448)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Offshore Structure / Suction effect / Caisson Structure / Poroelastic Medium / Pore water pressure / Compartment / Wave Pressure |
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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. In this research the seabed was assumed to be a fluid-saturated poroelasic medium whose behavior is governed by Biot's theory of wave propagation. Dynamic responses of a caisson structure with suction and seabed around it were numerically evaluated for wave pressures acting on the front surface of the caisson, which were measured under the irregular wave in the experimental basin. The effects of the skirt length and suction on the dynamic response of caisson structure foundation were numerically investigated for some material properties of seabed foundation.
The results obtained in this research is summarized as follows :
1)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)The pore water pressure response in seabed foundation depends on not only the suction and frictional force acting on the skirt part of a caisson structure but also the stiffness of seabed around it.
5)The caisson with suction is effective in soft seabed and has superiority in the cases of the lower permeability of seabed, the more providing compartments.
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