CA1203989A - System of subacqueous foundation module to be installed at great depths, for offshore selflifting platforms - Google Patents
System of subacqueous foundation module to be installed at great depths, for offshore selflifting platformsInfo
- Publication number
- CA1203989A CA1203989A CA000408885A CA408885A CA1203989A CA 1203989 A CA1203989 A CA 1203989A CA 000408885 A CA000408885 A CA 000408885A CA 408885 A CA408885 A CA 408885A CA 1203989 A CA1203989 A CA 1203989A
- Authority
- CA
- Canada
- Prior art keywords
- main
- base frame
- beams
- main support
- ballast
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
- E02B17/02—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor placed by lowering the supporting construction to the bottom, e.g. with subsequent fixing thereto
- E02B17/027—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor placed by lowering the supporting construction to the bottom, e.g. with subsequent fixing thereto steel structures
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
- E02B17/02—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor placed by lowering the supporting construction to the bottom, e.g. with subsequent fixing thereto
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
- E02B2017/0039—Methods for placing the offshore structure
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
- E02B2017/0039—Methods for placing the offshore structure
- E02B2017/0043—Placing the offshore structure on a pre-installed foundation structure
Abstract
ABSTRACT OF THE DISCLOSURE
A submarine foundation structure consists of three or more supporting struts which are completely submerged. The struts, in the form of a truss, are each supported by a base frame piled into the seabed. All the struts are connected together near their upper ends by means of connecting beams through double hinges. Each of the struts is ballasted at its lower end and is made buoyant at its upper end, so that due to the rigidity of the struts, the foundation structure is stable and in equilibrium on the base frames.
A submarine foundation structure consists of three or more supporting struts which are completely submerged. The struts, in the form of a truss, are each supported by a base frame piled into the seabed. All the struts are connected together near their upper ends by means of connecting beams through double hinges. Each of the struts is ballasted at its lower end and is made buoyant at its upper end, so that due to the rigidity of the struts, the foundation structure is stable and in equilibrium on the base frames.
Description
~3~
This invention relates to a submarine foundation structure for of.~shore platforms which allows construction at great depths, and offers the good stability and resistance to horizontal and vertical stresses under the most heavy con-ditions, sucn as occur in the North Sea.
According to the presentinvention there is provided a submarine foundation structure for installation at great depths for offshore platforms, comprising a plurality of main supporting struts, a corresponding number of base frames adapt-ed to be fixed on piles driven into the seabed, means for con-necting the lower ends of said main struts to their respective base frames, and connecting beams for interconnecting the upper ends of said main struts together.
The invention will now be described in more detail, by way of example only, with reference to the accompanying draw-ings, in which:-Fig. 1 is a lateral view of a complete foundation structure consisting of base frames, struts, an intermediate optional module, and a self-lifting platform;
Fig. 2 is a lateral view of the same system seen at 90 with respect to Fig. l;
Fig. 3 is a top view of the foundation structure according to the invention;
Figs. 4 to 14 illustrate various steps of installa-tions of said foundationstructure, which are self-explana-tory;
Fig. 15 shows a modified form of connection between the lower ends of the struts and the respective base frames;
and Figs. 16 and 17 show an embodiment having two super-imposed foundation structures.
The complete svstem shown in Figs. 1 and 2 comprises a self-lifting platform 11, the legs 10 of which are supported by and connected to the legs 9 ox an optional intermedia-te supporting module. This is mounted on a raft 8 connected to the upper ends of the main struts 2 of the foundation structure.
The lower ends of the foundation structure are hinged, by means of a universal joint 13, to respective base frames 1. These are fixed in the sea floor by means of piles 4. In the example shown in Fig. 1, the floor is at a depth of 650 m below sea level, and the platform is at 39 m above tne sea level. The foundation structure is completely below the wave action, as shown at the left of Fig. 1. At the right of Fig. 1 a section-al view of a strut 2 is shown, which is adapted to contain tanks or containers or may be assembled to form tanks.
The main struts 2 are ballasted at their lower ends, as indicated at 14 and contain buoyant material at their upper ends as indicated at 15. The main beams are connected together near their upper ends by means of connecting struts2 through double hinges 6,7.
In the embodiment shown in Figures 1 and 2, at the upper ends of the main struts 2, a raft 8 is connected thereto through double hinges 5. The raft supports an intermediate supporting system with legs 9, which in turn are connected to the legs 10 of the self-lifting platform 11.
The installation of the foundation structure will now be described with reference to Figures 4 to 15.
The embodiment shown has five main struts 2, which are indicated by A,B,C,D,E, in Fig. 4. First, the submarine smg used for installation measures the exact distances and de-termines the five base points. Then, with the aid of a convent tional construction ship, the piles 4 of the base frames 1 are driven into the seabed as shown in Fig. 5. The struts 2 are brought in position abcve the respective base points and, due to tlleir ballasted lower ends and buoyant upper ends, these 3~8~
struts can be brought to resi on the sea floor in a vertical position as shown in Fig. 6. The length of each main strut
This invention relates to a submarine foundation structure for of.~shore platforms which allows construction at great depths, and offers the good stability and resistance to horizontal and vertical stresses under the most heavy con-ditions, sucn as occur in the North Sea.
According to the presentinvention there is provided a submarine foundation structure for installation at great depths for offshore platforms, comprising a plurality of main supporting struts, a corresponding number of base frames adapt-ed to be fixed on piles driven into the seabed, means for con-necting the lower ends of said main struts to their respective base frames, and connecting beams for interconnecting the upper ends of said main struts together.
The invention will now be described in more detail, by way of example only, with reference to the accompanying draw-ings, in which:-Fig. 1 is a lateral view of a complete foundation structure consisting of base frames, struts, an intermediate optional module, and a self-lifting platform;
Fig. 2 is a lateral view of the same system seen at 90 with respect to Fig. l;
Fig. 3 is a top view of the foundation structure according to the invention;
Figs. 4 to 14 illustrate various steps of installa-tions of said foundationstructure, which are self-explana-tory;
Fig. 15 shows a modified form of connection between the lower ends of the struts and the respective base frames;
and Figs. 16 and 17 show an embodiment having two super-imposed foundation structures.
The complete svstem shown in Figs. 1 and 2 comprises a self-lifting platform 11, the legs 10 of which are supported by and connected to the legs 9 ox an optional intermedia-te supporting module. This is mounted on a raft 8 connected to the upper ends of the main struts 2 of the foundation structure.
The lower ends of the foundation structure are hinged, by means of a universal joint 13, to respective base frames 1. These are fixed in the sea floor by means of piles 4. In the example shown in Fig. 1, the floor is at a depth of 650 m below sea level, and the platform is at 39 m above tne sea level. The foundation structure is completely below the wave action, as shown at the left of Fig. 1. At the right of Fig. 1 a section-al view of a strut 2 is shown, which is adapted to contain tanks or containers or may be assembled to form tanks.
The main struts 2 are ballasted at their lower ends, as indicated at 14 and contain buoyant material at their upper ends as indicated at 15. The main beams are connected together near their upper ends by means of connecting struts2 through double hinges 6,7.
In the embodiment shown in Figures 1 and 2, at the upper ends of the main struts 2, a raft 8 is connected thereto through double hinges 5. The raft supports an intermediate supporting system with legs 9, which in turn are connected to the legs 10 of the self-lifting platform 11.
The installation of the foundation structure will now be described with reference to Figures 4 to 15.
The embodiment shown has five main struts 2, which are indicated by A,B,C,D,E, in Fig. 4. First, the submarine smg used for installation measures the exact distances and de-termines the five base points. Then, with the aid of a convent tional construction ship, the piles 4 of the base frames 1 are driven into the seabed as shown in Fig. 5. The struts 2 are brought in position abcve the respective base points and, due to tlleir ballasted lower ends and buoyant upper ends, these 3~8~
struts can be brought to resi on the sea floor in a vertical position as shown in Fig. 6. The length of each main strut
2 is determined according to the measured positions of the base points. Near the lower ends of the struts 2 a reel 16 is arranged carrying a steel cable 17. The submarine smg now un-winds the cable 17 from the reel 16 and connects its free end to the base frame 1. The submarine smg, through a flexible pipe 20, unloads a certain quantity of the ballast 14 contained in the lower end of the strut so that the strut will orient itself upwards in a vertical position above the base frame 1,4, as shown in Fig. 7. The submarine disconnects the flexible pipe 20 from the strut and connects the steel cables 18, un-winding them from winches 19 arranged on the hinged universal joint end 13 of the strut 2, with the base frame 1, see Figs.
7 and 8. The submarine smg then activates the winches 19 to wind up the cables 18 on the winches 19, so that the strut 2 is lowered and its hinged end 13 is engaged with the base frame 1, as shown in Fig. 9. At the end of this operation, the strut 2 will be hinged with its universal joint end 13 on the base frame 1 and will be in vertical position due to the buo-yant material contained in its upper end. The connecting beam 3 is now brought into position above the struts 2. With the aid of a diving bell 23, or the submarine smg, steel cables 22 wound on reels 21 arranged on the connecting beam 3, are connected to the struts 2. After this connection has been effected, the reels 22 are activated until the hinge-parts 6,7 of the beam 3 are brought to meet the corresponding hinge-parts 6,7 of the struts 2. Thereafter pins are inserted into the hinges so that the beams 2-3 are connected together as shown in Fig. 11.
Now the self~lifting platform ]1 may be installed directly onto the upper ends of the struts 2 of the foundation
7 and 8. The submarine smg then activates the winches 19 to wind up the cables 18 on the winches 19, so that the strut 2 is lowered and its hinged end 13 is engaged with the base frame 1, as shown in Fig. 9. At the end of this operation, the strut 2 will be hinged with its universal joint end 13 on the base frame 1 and will be in vertical position due to the buo-yant material contained in its upper end. The connecting beam 3 is now brought into position above the struts 2. With the aid of a diving bell 23, or the submarine smg, steel cables 22 wound on reels 21 arranged on the connecting beam 3, are connected to the struts 2. After this connection has been effected, the reels 22 are activated until the hinge-parts 6,7 of the beam 3 are brought to meet the corresponding hinge-parts 6,7 of the struts 2. Thereafter pins are inserted into the hinges so that the beams 2-3 are connected together as shown in Fig. 11.
Now the self~lifting platform ]1 may be installed directly onto the upper ends of the struts 2 of the foundation
3~
structure, or, alternatively, as shown in Figs. 12 and 13, an intermediate supporting module 9 mounted on a raft 8, which carried reels 24 with steel cables 25, may be mounted and fixed on the upper ends of the struts 2 of the foundation structure.
The hinged parts 13 at the lower ends of the struts 2 can now be fixed by cement in the base frame 1 as shown in Fig. 14. At least the ballast 14 and the buoyant material 15 are brought to the best relation, so that the struts 2 are kept under ten-sion. The relation between the weight and -the buoyancy is such that the base frames 1,4 are never loaded in tension, and each strut 2 is balanced on its universal joint 13.
Fig. 15 shows an alternative arrangement for the con-nection of the lower ends of the struts 2 with the base frames 1. The struts 2 with a shaped part 13 on a correspondingly shaped base frame 1 instead of being hingeu thereto.
Figures 16 and 17 show an embodiment for use at still greater depths, wherein two foundation structures are arranged one above the other.
According to still another embodiment, not shown in the .Figures, connecting beams between the main s-truts may also be arranged near the lower ends of the main struts and connect-ed thereto by means of double hinges as shown for the connect-ing beams at the upper ends of the main struts.
structure, or, alternatively, as shown in Figs. 12 and 13, an intermediate supporting module 9 mounted on a raft 8, which carried reels 24 with steel cables 25, may be mounted and fixed on the upper ends of the struts 2 of the foundation structure.
The hinged parts 13 at the lower ends of the struts 2 can now be fixed by cement in the base frame 1 as shown in Fig. 14. At least the ballast 14 and the buoyant material 15 are brought to the best relation, so that the struts 2 are kept under ten-sion. The relation between the weight and -the buoyancy is such that the base frames 1,4 are never loaded in tension, and each strut 2 is balanced on its universal joint 13.
Fig. 15 shows an alternative arrangement for the con-nection of the lower ends of the struts 2 with the base frames 1. The struts 2 with a shaped part 13 on a correspondingly shaped base frame 1 instead of being hingeu thereto.
Figures 16 and 17 show an embodiment for use at still greater depths, wherein two foundation structures are arranged one above the other.
According to still another embodiment, not shown in the .Figures, connecting beams between the main s-truts may also be arranged near the lower ends of the main struts and connect-ed thereto by means of double hinges as shown for the connect-ing beams at the upper ends of the main struts.
Claims (26)
PROPERTY OR PRIVILEGE IS CLAIMED ARE ARE DEFINED AS FOLLOWS:
1. A system for forming a foundation module to be installed submerged completely at great depths for support-ing off-shore self-lifting platforms, comprising a plurality of elongated main supporting beams, each main beam comprising a hollow network structure, each main beam having an upper end and a lower end when installed, a floating material located in the upper end of each main beam and a ballast located in the lower end of each main beam, means to adjust the relative quantities of the floating material and the ballast in each main beam such that the main beam, when installed, is under tension, a base frame fixed on a pile driven into the sea floor corresponding to each main beam, means pivotally connecting each said main beam to each said corresponding base frame, and a connecting beam connecting adjacent main beams, said connecting beam being con-nected to said main beam by double hinges.
2. A system according to claim 1, in which each main beam is connected to its respective base frame by means of a cardanic joint.
3. A system according to claim 1, in which said main beam contains, near its lower end, at least one reel having a steel cable having a free end, said free end being formed to be connected to the respective base frame, in order to hold the beam in vertical position above the base frame.
4. A system according to claim 2, in which the car-danic joint at the lower end of each main beam carries two winches with steel cables having free ends, each free end being formed to be connected to a respective base frame in order to bring the said cardanic joint into engagement with the base frame.
5. A system according to claim 1, in which the con-necting beam carries winches with steel cables having free ends formed to be connected to the upper ends of the main beams in order to bring hinge-parts of the connecting beam to meet the corresponding hinge-parts of the main beam to form said hinges.
6. A system according to claim 1, in which after the engagement of the cardanic joint with the base frame, the said joint is fixed by cement in the base frame.
7. A system according to claim 1, in which the engagement of the lower end of the main beam with the base frame is only a resting engagement with correspondingly shaped parts.
8. A system according to claim 1, in which two foun-dation modules with main beams are superimposed.
9. A system according to claim 1, in which the main beams are connected together by further connecting beams near their lower ends.
10. A method of forming a foundation module to be installed at great depth in the sea, the module having a plurality of elongated main support beams having a ballasted end and a floated end having floating material and a corresponding plurality of base frames, the method comprising the steps of (a) locating the base frames in spaced relationships on the floor of the sea, (b) fixing the base frames to the floor of the sea, (c) adding ballast to the ballasted end of each said main support beam to submerge the main support beam to rest vertically on the sea floor, (d) removing a portion of the ballast from each said main support beam sufficient to cause the main support beam to begin a float vertically, (e) positioning the vertically float-ing beam above an associated base frame, (f) installing the vertically floating beam on its associated base frame, (g) adjusting the relative quantities of the ballast and the float-ing material such that the main support beam is under tension and rests in equilibrium on its associated base frame, and (h) installing a connecting beam between said main support beams with the connection between said connecting beam and said main support beams being a hinged connection.
11. The method according to claim 10, in which method step (h) includes the step of installing the connecting beam such that said main support beams are inclined towards one another.
12. The method according to claim 10, in which method steps (d) through (f) are performed separately for each main sup-port beam.
13. The method according to claim 12, including the further step of installing cement in each base frame following method step (h).
14. A system for forming a foundation module to be installed submerged completely at great depths for supporting offshore self-lifting platforms, comprising: a plurality of elon-gated main supporting beams, each main beam comprising a hollow network structure, each main beam having an upper end and a lower end when installed, a floating material located in the upper end of each main beam and a ballast located in the lower end of each main beam, means to adjust the relative quantities of the float-ing material and the ballast in each main beam such that the main beam, when installed, is under tension, a base frame fixed on a pile driven into the sea floor corresponding to each main beam, means pivotally connecting said main beam to each said corres-ponding base frame, and a connecting beam connecting adjacent main beams, said connecting beam being connected to said main body by double hinges.
15. A system according to claim 14, in which each main beam is connected to its respective base frame by means of a cardanic joint.
16. A system according to claim 14, in which said main beam contains, near its lower end, at least one reel having a steel cable having a free end, said free end being formed to be connected to the respective base frame, in order to hold the beam in vertical position above the base frame.
17. A system according to claim 15, in which the car-danic joint at the lower end of each main beam carries two winches with steel cables having free ends, each free end being formed to be connected to a respective base frame in order to bring the said cardanic joint into engagement with the base frame.
18. A system according to claim 14, in which the con-necting beam carries winches with steel cables having free ends formed to be connected to the upper ends of the main beams in order to bring hinge-parts of the connecting beam to meet the corresponding hinge-parts of the main beams to form said hinges.
19. A system according to claim 14, in which after the engagement of the cardanic joint with the base frame the said joint is fixed by cement in the base frame.
20. A system according to claim 14, in which the engage-ment of the lower end of the main beam with the base frame is only a resting engagement with correspondingly shaped parts.
21. A system according to claim 14, in which two foundation modules with main beams are superimposed.
22. A system according to claim 14, in which the main beams are connected together by further connecting beams near their lower ends.
23. A method of forming a foundation module to be in-stalled at great depth in the sea, the module having a plurality of elongated main support beams having a ballasted end and a floated end having floating material and a corresponding plurality of base frames, the method comprising the steps of (a) locating the base frames in spaced relationships on the floor of the seal (b) fixing the base frames to the floor of the sea, (c) adding ballast to the ballasted end of each said main support beam to submerge the main support beam to rest vertically on the sea floor, (d) removing a portion of the ballast from each said main support beam sufficient to cause the main support beam to begin a float vertically, (e) positioning the vertically floating beam above an associated base frame, (f) installing the vertically floating beam on its associated base frame, (g) adjusting the relative quantities of the ballast and the floating material such that the main support beam is under tension and rests in equili-brium on its associated base frame and (h) installing a connecting beam betwen said main support beams with the connection betwen said connecting beam and said main support beams being a hinged connection.
24. The method according to claim 23, in which method step (h) includes the step of installing the connecting beam such that said main support beams are inclined toward one another.
25. The method according to claim 23, in which method steps (d) through (f) are performed separately for each main support beam.
26. The method according to claim 23 including the further step of installing cement in each base frame following method step (h).
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP19820106808 EP0099938B1 (en) | 1982-07-28 | 1982-07-28 | Under-water supporting construction and its installation in deep waters for self raising sea platforms |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1203989A true CA1203989A (en) | 1986-05-06 |
Family
ID=8189149
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000408885A Expired CA1203989A (en) | 1982-07-28 | 1982-08-06 | System of subacqueous foundation module to be installed at great depths, for offshore selflifting platforms |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0099938B1 (en) |
| AU (1) | AU555240B2 (en) |
| CA (1) | CA1203989A (en) |
| DE (1) | DE3270405D1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014089656A1 (en) * | 2012-12-11 | 2014-06-19 | Fonseca David Verly Da | Floating platform with submerged anchoring means |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NO155297C (en) * | 1984-12-04 | 1987-03-11 | Norsk Hydro As | ESTABLISHED MARINE STEEL CONSTRUCTION AND PROCEDURE AND MEANS FOR COMPOSITION OF THE CONSTRUCTION. |
| US4669918A (en) * | 1986-02-04 | 1987-06-02 | Riles William G | Offshore platform construction including preinstallation of pilings |
| GB2302119B (en) | 1994-05-02 | 1998-02-18 | Shell Int Research | A method for templateless foundation installation of a tlp |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1423492A (en) * | 1973-05-04 | 1976-02-04 | Fluor Corp | Offshore platform structures and method for the construction thereof |
| FR2359248A1 (en) * | 1976-07-23 | 1978-02-17 | Doris Dev Richesse Sous Marine | Submersible columns for supporting platforms above water level - which rest on ball connectors to allow racking but maintain vertical alignment |
| DE2736937C3 (en) * | 1977-08-16 | 1981-04-16 | Howaldtswerke-Deutsche Werft Ag Hamburg Und Kiel, 2300 Kiel | Procedure for the construction of an offshore structure |
| GB2054710A (en) * | 1979-05-25 | 1981-02-18 | Cjb Bearl & Wright Ltd | Levelling seabed templates |
| DE2938181A1 (en) * | 1979-09-21 | 1981-04-09 | M.A.N. Maschinenfabrik Augsburg-Nürnberg AG, 8500 Nürnberg | Offshore oil drilling platform - having automatically controlled water pumps in feed to extend legs to provide stable footing on uneven sea bed |
-
1982
- 1982-07-28 EP EP19820106808 patent/EP0099938B1/en not_active Expired
- 1982-07-28 DE DE8282106808T patent/DE3270405D1/en not_active Expired
- 1982-08-05 AU AU86792/82A patent/AU555240B2/en not_active Ceased
- 1982-08-06 CA CA000408885A patent/CA1203989A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014089656A1 (en) * | 2012-12-11 | 2014-06-19 | Fonseca David Verly Da | Floating platform with submerged anchoring means |
Also Published As
| Publication number | Publication date |
|---|---|
| AU555240B2 (en) | 1986-09-18 |
| AU8679282A (en) | 1984-02-09 |
| DE3270405D1 (en) | 1986-05-15 |
| EP0099938B1 (en) | 1986-04-09 |
| EP0099938A1 (en) | 1984-02-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |