Patent US4045968A successfully refreshed from Google Patents.
US4045968A
Expired / Lapsed
US
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Offshore platform and method for its installation
Assignee: Kajima Corp
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Filing: 1975-12-24
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Granted: 1977-09-06
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Expires: 1995-12-24
Abstract
Abstract A platform and method are suited for use in connection with offshore drilling in earthquake-vulnerable areas where the sea floor is soft. Caissons project downwardly from the base raft into the sea floor layer, thereby giving the platform a resistance to horizontal forces. The caissons are connected to the platform by energy absorbing means which yield to permit relative movement when subjected to earthquake-produced forces.
Inventors
- 👤 Benjamin C. Gerwick, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:58
CPC Classifications
E; E02; E02B; E02B17/00; E02B17/02; E02B17/025; E02B2017/0056; E02B2017/0069; E02B2017/0073; E02B2017/0086
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
113 words
A concrete platform for use in offshore drilling and the like, comprising a superstructure and a base structure, said superstructure including a deck and supporting towers, said base structure including a base raft and caissons, said caissons extending downwardly from the base raft to be embedded in the soil of the sea floor layer whereby external horizontal forces acting on the platform are opposed by soil pressure acting laterally on the sunken portions of the caissons, energy absorbing means interconnecting said caissons and said base raft, said energy absorbing means including (a) members which are relatively rigid under wave forces but which fail under strong earthquake and (b) an energy-absorbing resilient (elastic) material.
Claim 2
Dependent Claim
113 words
A concrete platform for use in offshore drilling and the like, comprising a superstructure and a base structure, said superstructure including a deck and supporting towers, said base structure including a base raft and caissons, said caissons extending downwardly from the base raft to be embedded in the soil of the sea floor layer whereby external horizontal forces acting on the platform are opposed by soil pressure acting laterally on the sunken portions of the caissons, energy absorbing means interconnecting said caissons and said base raft, said energy absorbing means including (a) members which are relatively rigid under wave forces but which fail under strong earthquake and (b) an energy-absorbing resilient (elastic) material.
Claim 3
Dependent Claim
40 words
The concrete platform of claim 1 wherein said caissons extend at least about 20 meters into the sea floor layer so as to lie below a depth at which the sea bottom layer is fluidized by liquefaction during an earthquake.
Claim 4
Dependent Claim
57 words
The concrete platform of claim 1 having wells extending therebeneath to a depth of at least 20 meters below the sea floor surface, means for pumping water from said wells to reduce the interstitial hydrostatic pressure within the sea floor layer and prevent fluidization by liquefaction of the sea floor layer in the event of an earthquake.
Claim 5
Dependent Claim
27 words
The concrete platform of claim 1 wherein said base raft has a downwardly facing surface extending laterally beyond said caissons for resting on the sea floor surface.
Claim 6
Dependent Claim
26 words
The concrete platform of claim 4 wherein the downwardly facing surface area of the base raft is greater than the downwardly facing area of the caissons.
Claim 7
Dependent Claim
16 words
The concrete platform of claim 1 having energy-absorbing means interconnecting said caissons and said base raft.
Claim 8
Dependent Claim
36 words
The concrete platform of claim 1 wherein a portion of said caisson and a portion of said base raft are interfitted in a given horizontal plane, said energy absorbing means lying in said given horizontal plane.
Claim 9
Dependent Claim
27 words
The concrete platform of claim 7 wherein said base raft has a downwardly facing surface extending laterally beyond said caissons for resting on the sea floor surface.
Claim 10
Dependent Claim
40 words
The concrete platform of claim 8 wherein said caissons extend at least about 20 meters into the sea floor layer so as to lie below a depth at which the sea bottom layer is fluidized by liquefaction during an earthquake.
Claim 11
Dependent Claim
102 words
A concrete platform for use in offshore drilling and the like, comprising a deck, supporting towers, a base raft, caissons and energy absorbing means for absorbing earthquake energy generated in the event of earthquake, said energy absorbing means holding said caissons stationary with respect to the platform until forces therebetween exceed a magnitude which occurs during an earthquake at which point the energy absorbing means allows a relative displacement between the caissons and the platform, said energy absorbing means including (a) members which are relatively rigid under wave forces but which fail under strong earthquake and (b) an energy-absorbing resilient (elastic) material.
Claim 12
Dependent Claim
102 words
A concrete platform for use in offshore drilling and the like, comprising a deck, supporting towers, a base raft, caissons and energy absorbing means for absorbing earthquake energy generated in the event of earthquake, said energy absorbing means holding said caissons stationary with respect to the platform until forces therebetween exceed a magnitude which occurs during an earthquake at which point the energy absorbing means allows a relative displacement between the caissons and the platform, said energy absorbing means including (a) members which are relatively rigid under wave forces but which fail under strong earthquake and (b) an energy-absorbing resilient (elastic) material.
Claim 13
Dependent Claim
17 words
The platform of claim 10 wherein said energy absorbing means interconnects said caissons and said base raft.
Claim 14
Dependent Claim
51 words
A concrete platform according to claim 10 wherein portions thereof include flotation chamber means for creating a permanent buoyancy to minimize the effective weight of the platform imposed on the sea bottom floor, whereby the platform is capable of being installed and erected on a soft or weak sea bottom layer.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-09-05 | 1981-03-07 | 1981-09-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-05 | 1985-03-07 | 1985-09-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-05 | 1989-03-07 | 1989-09-06 | $7700.00 | Window Closed / Lapsed |