EP0065695A1 - Leg of an offshore platform and method of placing it - Google Patents

Leg of an offshore platform and method of placing it Download PDF

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Publication number
EP0065695A1
EP0065695A1 EP82104068A EP82104068A EP0065695A1 EP 0065695 A1 EP0065695 A1 EP 0065695A1 EP 82104068 A EP82104068 A EP 82104068A EP 82104068 A EP82104068 A EP 82104068A EP 0065695 A1 EP0065695 A1 EP 0065695A1
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EP
European Patent Office
Prior art keywords
leg
insert
platform
legs
barge
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Granted
Application number
EP82104068A
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German (de)
French (fr)
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EP0065695B1 (en
Inventor
Jean-Louis Ninet
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Alsthom Atlantique SA
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Alsthom Atlantique SA
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    • 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
    • E02B17/021—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 with relative movement between supporting construction and platform
    • E02B17/024—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 with relative movement between supporting construction and platform shock absorbing means for the supporting construction

Definitions

  • the invention applies to any platform intended to be placed at sea on a fixed structure preinstalled and which is therefore subject, at the time of its installation, to the action of the swell.
  • the platform conveyed from its place of construction on a transport barge, comprises legs which, at the end of the operation, must rest on determined locations on the structure, (generally piles which protrude from the surface of the water) and be secured to this structure, most generally by welding.
  • This operation is easily carried out in the river or in a site protected from swell by simple ballasting of the transport barge.
  • the swell is not regular, but has trains of waves interspersed with periods of relative calm, it is imperative to have a system to ensure the connection in the horizontal plane between platform and structure in a time less than the duration of the periods of calm, that is to say, in the majority of cases, less than a minute.
  • a classic solution is to suspend the platform at the end of a crane carried by a barge and drop it suddenly, at the time of the coincidence between the piles of the structure and the legs of the platform. Crane operators are skilled enough to succeed in this maneuver.
  • An object of the invention is therefore to define a device making it possible to achieve in a much more economical manner, a almost instantaneous connection between a platform equipped with legs and the heads of the piles of a fixed structure intended to receive the platform.
  • the subject of the invention is a leg of a marine platform engaging on a pile belonging to a fixed structure and the head of which has a female receiving cone, said platform having legs equal in number to the piles, each leg being intended to be fixed to a stack, said leg being hollow and enclosing an insert which can slide in the leg and intended to secure the leg and the corresponding stack by its partial introduction into the receiving cone, characterized in that the insert is associated with a means which makes it possible to secure it to the leg and to suddenly detach it, causing the insert to fall by gravity.
  • the means comprises at least one finger passing through the leg and cooperating with a bore of the insert.
  • a wedge crossing the leg is inserted into each of the legs concerned above the insert by orifices facing each other in pairs.
  • FIG. 1A schematically represents a platform 1 carried by a transport barge 2.
  • a structure intended to receive the platform On the bottom of the sea 3 is anchored a structure intended to receive the platform.
  • This structure includes piles whose heads can emerge from the water; one of these battery heads, referenced 4, is shown in the figures. It has a receiving cone 5, female.
  • Each stack 4 corresponds to a leg 6 secured to the platform 1.
  • a platform may for example include four legs which will be secured to 4 stacks.
  • At least two of the legs consist of a hollow cylinder closed at the upper end by a stop 7 generally called a lifter. It is legs of this type which are shown in the figures.
  • the transport barge is positioned using anchor lines, the platform and its legs passing freely above the pile heads.
  • the distance (or clear) between the lower end of the insert and the pile head depends on the tide, the amplitude of the barge's vertical movements and certain factors of security. This value is designated by AGo.
  • the transport barge is first ballasted until the clear AGo is reduced to a minimum value compatible with the vertical movements of the assembly and in such a way that there is no contact between pile head and leg of the platform. This is the position shown in Figure 1A.
  • inserts are released simultaneously and fall into the cones of reception of the battery heads, instantly making the horizontal connection between the platform -form and structure.
  • the number of inserts to be dropped simultaneously depends on their capacity and that of the stacks of the structure to withstand the horizontal forces generated by the wave trains. Their number is at least two to avoid any rotation of the platform which could occur after connection on a single insert and which would prevent the others from going down into the receiving cones.
  • the barge-platform assembly remains free to move vertically with the swell, along the insert.
  • the depth of the reception cone will advantageously be taken at least equal to the value of the maximum possible heave to prevent any accidental dislocation of an insert after friction connection of the insert inside the leg, at the moment of the passage of wave trains.
  • the receiving cone can advantageously be mounted on a damper 14 made of rubber, elastomer or any other suitable elastic material, to absorb the shock created by the fall of the insert and to ensure that the latter does not damage the battery head of the structure, if the centering of the platform is not perfect when the inserts are released.
  • FIG 1D shows the crash of the shock absorber at the end of ballasting.
  • the length of the insert and the location of the spreader inside the leg are studied so that the distance, at the end of the operation, between the lower end of the platform leg and the pile head of the structure is sufficient to allow two metal half-ferrules (16A and 16B) to be welded, which ultimately ensure the continuity of the structure installed between the stack and the leg of the platform.
  • the relief height D is close to 2 meters. If the initial clear is 0.6 meters and the heaving 0.9 m, the ballasting height is close to 4 meters; ballasting then requires a very large quantity of water, of the order of 13,000 tonnes.
  • a variant of the system makes it possible to reduce this ballasting height; this variant will preferably apply to very large platforms.
  • FIGS. 2A to 2E show the variant of the device of the invention using this wedge.
  • the leg is provided with orifices 20A, 20B, 21A, 21B facing two by two.
  • a shim 19 is introduced by a pair of orifices (here the orifices 21A, 21B lower), so as to serve as a stop for the insert at the end of ballasting ( Figure 2D).
  • FIG. 2E shows the final position of the various elements after welding of two half-ferrules 16A and 16B and destruction of the damper.
  • the wedge is mounted on a slide (not shown) which crosses the leg of the platform so as not to impede the sliding of the insert - passing, for example, on either side of the insert to the inside of the leg -and is extended to the outside of the leg where the wedge is in the waiting position before connection.
  • the insertion of the wedge inside the leg can be done manually or using a mechanical device such as for example a jack (not shown) whose required capacity is limited to the value of the friction due to the dead weight of the hold.
  • a mechanical device such as for example a jack (not shown) whose required capacity is limited to the value of the friction due to the dead weight of the hold.
  • An additional advantage of this variant lies in the fact that, after releasing the inserts, the resumption of the horizontal forces due to the swell induces smaller moments in the inserts, the distance between the bottom of the reception cone and the guide 9 mounted at the lower end of the leg being reduced relative to the device of FIGS. 1A to 1E, by a length equal to that of the protrusion of the insert under the leg; this length can reach 1.5 meters.

Abstract

L'invention a pour objet une jambe d'une plate-forme marine s'engageant sur une pile d'une structure fixe et dont la tête présente un cône récepteur, ladite plate-forme présentant des jambes en nombre égal aux piles chaque jambe étant destinée à être fixée à une pile, ladite jambe étant creuse et enfermant un insert pouvant coulisser dans la jambe et destiné à solidariser la jambe et la pile correspondante par son introduction partielle dans le cône récepteur, caractérisé en ce que l'insert (8) est associé à un moyen (10, 11) qui permet de le solidariser à la jambe et de le désolidariser brusquement, provoquant la chute de l'insert par gravitéThe subject of the invention is a leg of a marine platform engaging on a pile of a fixed structure and the head of which has a receiving cone, said platform having legs equal in number to the piles, each leg being intended to be fixed to a stack, said leg being hollow and enclosing an insert which can slide in the leg and intended to secure the leg and the corresponding stack by its partial introduction into the receiving cone, characterized in that the insert (8) is associated with a means (10, 11) which makes it possible to secure it to the leg and to suddenly detach it, causing the insert to fall by gravity

Application à la mise en place de plate-formes marines.

Figure imgaf001
Application to the establishment of marine platforms.
Figure imgaf001

Description

L'invention s'applique à toute plate-forme destinée à être placée en mer sur une structure fixe préinstallée et qui est donc soumise, au moment de sa pose, à l'action de la houle.The invention applies to any platform intended to be placed at sea on a fixed structure preinstalled and which is therefore subject, at the time of its installation, to the action of the swell.

La plate-forme, acheminée depuis son lieu de construction sur une barge de transport, comporte des jambes qui, en fin d'opération, doivent reposer sur des emplacements déterminés de la structure, (généralement des piles qui dépassent de la surface de l'eau) et être solidarisées à cette structure, le plus généralement par soudure.The platform, conveyed from its place of construction on a transport barge, comprises legs which, at the end of the operation, must rest on determined locations on the structure, (generally piles which protrude from the surface of the water) and be secured to this structure, most generally by welding.

Cette opération se réalise facilement en rivière ou en site protégé de la houle par simple ballastage de la barge de transport.This operation is easily carried out in the river or in a site protected from swell by simple ballasting of the transport barge.

En mer, une des principales difficultés réside, au moment du contact entre la plate-forme et la sous-structure, dans le fait que, la barge de transport, et par conséquent la plate-forme qui repose sur elle, étant soumises à la houle, sont animées à un mouvement horizontal alternatif de période égale à celle de la houle.At sea, one of the main difficulties lies, at the time of contact between the platform and the substructure, in the fact that, the transport barge, and consequently the platform which rests on it, being subjected to the swell, are driven in an alternating horizontal movement of period equal to that of the swell.

Pour réaliser la connexion entre plate-forme et structure, il est nécessaire que les piles de la structure et les jambes de la plate-forme soient en coïncidence.To make the connection between platform and structure, it is necessary that the piles of the structure and the legs of the platform are in coincidence.

Du fait que la houle n'est pas régulière, mais présente des trains de vagues entrecoupés de périodes de calme relatif, il est impératif de disposer d'un système permettant d'assurer la liaison dans le plan horizontal entre plate-forme et structure dans un temps inférieur à la durée des périodes de calme, c'est-à-dire, dans la majorité des cas, inférieur à la minute.Because the swell is not regular, but has trains of waves interspersed with periods of relative calm, it is imperative to have a system to ensure the connection in the horizontal plane between platform and structure in a time less than the duration of the periods of calm, that is to say, in the majority of cases, less than a minute.

Une solution classique est de suspendre la plate-forme au bout d'une grue portée par une barge et de la laisser tomber brusquement, au moment de la coïncidence entre les piles de la structure et les jambes de la plate-forme. Les grutiers sont assez habiles pour réussir une telle manoeuvre.A classic solution is to suspend the platform at the end of a crane carried by a barge and drop it suddenly, at the time of the coincidence between the piles of the structure and the legs of the platform. Crane operators are skilled enough to succeed in this maneuver.

Ce type de solution conduit à la mise en oeuvre des moyens navals très onéreux dès que les plate-formes atteignent un poids de l'ordre du millier de tonnes.This type of solution leads to the implementation of very expensive naval means as soon as the platforms reach a weight of the order of a thousand tonnes.

Un but de l'invention est donc de définir un dispositif permettant de réalisa de manière beaucoup plus économique, une connexion quasi-instantanée entre une plate-forme équipée de jambes et les têtes des piles d'une structure fixe destinée à recevoir la plate-forme.An object of the invention is therefore to define a device making it possible to achieve in a much more economical manner, a almost instantaneous connection between a platform equipped with legs and the heads of the piles of a fixed structure intended to receive the platform.

L'invention a pour objet une jambe d'une plate-forme marine s'engageant sur une pile appartenant à une structure fixe et dont la tête présente un cône récepteur femelle, ladite plate-forme présentant des jambes en nombre égal aux piles, chaque jambe étant destinée à être fixée à une pile, ladite jambe étant creuse et enfermant un insert pouvant coulisser dans la jambe et destiné à solidariser la jambe et la pile correspondante par son introduction partielle dans le cône récepteur, caractérisé en ce que l'insert est associé à un moyen qui permet de le solidariser à la jambe et de le désolidariser brusquement, provoquant la chute de l'insert par gravité.The subject of the invention is a leg of a marine platform engaging on a pile belonging to a fixed structure and the head of which has a female receiving cone, said platform having legs equal in number to the piles, each leg being intended to be fixed to a stack, said leg being hollow and enclosing an insert which can slide in the leg and intended to secure the leg and the corresponding stack by its partial introduction into the receiving cone, characterized in that the insert is associated with a means which makes it possible to secure it to the leg and to suddenly detach it, causing the insert to fall by gravity.

Dans un mode particulier de réalisation le moyen comprend au moins un doigt traversant la jambe et coopérant avec un alésage de l'insert.In a particular embodiment the means comprises at least one finger passing through the leg and cooperating with a bore of the insert.

L'invention a également pour objet un procédé de mise en oeuvre d'un dispositif pour la mise en place d'une plate-forme sous-marine portée par une barge sur une structure fixe au moyen d'un dispositif selon la revendication 1, caractérisé en ce qu'il comprend les phases suivantes :

  • a/ on approche la barge de la structure de manière à mettre les jambes au-dessus des têtes de piles
  • b/ on désolidarise brusquement au moins deux inserts de leur jambe respective par action simultanée des moyens de solidarisation correspondants.
  • c/ on désolidarise les autres inserts éventuels
  • d/ on balaste la barge jusqu'à permettre son éloignement de la structure
  • e/ on effectue la liaison définitive entre chaque jambe et pile correspondante.
The subject of the invention is also a method of implementing a device for the establishment of an underwater platform carried by a barge on a fixed structure by means of a device according to claim 1, characterized in that it comprises the following phases:
  • a / we approach the barge of the structure so as to put the legs above the pile heads
  • b / at least two inserts are suddenly separated from their respective legs by simultaneous action of the corresponding securing means.
  • c / we separate the other possible inserts
  • d / we ballast the barge to allow it to move away from the structure
  • e / the final connection is made between each leg and corresponding pile.

Avantageusement entre les phases c/ et d/ on insère dans chacune des jambes concernées une cale traversant la jambe au-dessus de l'insert par des orifices se faisant face deux à deux.Advantageously between phases c / and d / a wedge crossing the leg is inserted into each of the legs concerned above the insert by orifices facing each other in pairs.

L'invention sera bien comprise par la description donnée ci-après de deux modes préférés de réalisation de l'invention, en référence au dessin annexé dans lequel :

  • -les figures 1A et 1E représentent schématiquement le dispositif de l'invention et illustrent un procédé pour sa mise en oeuvre.
  • - les figures 2A à 2E illustrent une variante du dispositif du procédé pour sa mise en oeuvre.
The invention will be better understood from the description given below of two preferred embodiments of the invention, in reference to the attached drawing in which:
  • FIGS. 1A and 1E schematically represent the device of the invention and illustrate a method for its implementation.
  • - Figures 2A to 2E illustrate a variant of the device of the method for its implementation.

La figure 1A représente schématiquement une plate-forme 1 portée par une barge de transport 2. Sur le fond de la mer 3 est ancrée une structure destinée à recevoir la plate-forme. Cette structure comporte des piles dont les têtes peuvent émerger de l'eau ; l'une de ces têtes de pile, référencée 4, est représentée dans les figures. Elle possède un cône de réception 5, femelle.FIG. 1A schematically represents a platform 1 carried by a transport barge 2. On the bottom of the sea 3 is anchored a structure intended to receive the platform. This structure includes piles whose heads can emerge from the water; one of these battery heads, referenced 4, is shown in the figures. It has a receiving cone 5, female.

A chaque pile 4 correspond une jambe 6 solidaire de la plate-forme 1. Une plate-forme pourra comprendre par exemple quatre jambes qui seront solidarisées à 4 piles.Each stack 4 corresponds to a leg 6 secured to the platform 1. A platform may for example include four legs which will be secured to 4 stacks.

Au moins deux des jambes sont constituées d'un cylindre creux fermé à l'extrémité supérieure par une butée 7 appelée généralement palonnier. Ce sont des jambes de ce type qui sont représentées dans les figures.At least two of the legs consist of a hollow cylinder closed at the upper end by a stop 7 generally called a lifter. It is legs of this type which are shown in the figures.

A l'intérieur du tube est disposé un insert 8 dont les caractéristiques sont les suivantes :

  • - il peut coulisser dans la jambe dans laquelle il est guidé par des moyens 9 tels que des bossages, (et/ou des plaques telle que 9A).
  • - il est maintenu à l'intérieur de la jambe, en butée contre le palonnier, au moyen d'un dispositif mécanique, qui peut par exemple être un doigt 10, traversant la jambe par un orifice approprié, et s'engageant dans un alésage correspondant de l'insert. Le doigt est escamotable au moyen d'un vérin 11. En variante, il peut y avoir plusieurs doigts déplaçables simultanément.
  • - il est terminé par un cône 12 destiné à faciliter son centrage dans le cône récepteur 5 de la tête de pile 4.
  • - il dépasse de la jambe à son extrémité inférieure.
  • - il est constitué de deux tubes 8A et 8B coaxiaux, fixés chacun par l'une de leur extrémité à un dispositif amortisseur 14, de préférence constitué d'un bloc en matériau élastomère.
Inside the tube is an insert 8, the characteristics of which are as follows:
  • - It can slide in the leg in which it is guided by means 9 such as bosses, (and / or plates such as 9A).
  • - It is held inside the leg, in abutment against the lifter, by means of a mechanical device, which can for example be a finger 10, passing through the leg through an appropriate orifice, and engaging in a bore correspondent of the insert. The finger is retractable by means of a jack 11. As a variant, there can be several fingers that can be moved simultaneously.
  • - it is terminated by a cone 12 intended to facilitate its centering in the receiving cone 5 of the battery head 4.
  • - it protrudes from the leg at its lower end.
  • - It consists of two coaxial tubes 8A and 8B, each fixed by one of their ends to a damping device 14, preferably consisting of a block of elastomeric material.

Le fonctionnement du dispositif est le suivant :

  • Durant le transport, l'insert 8 est rentré à l'intérieur de la jambe et est maintenu en butée contre le palonnier 7.
The operation of the device is as follows:
  • During transport, the insert 8 is inserted inside the leg and is held in abutment against the lifter 7.

La barge de transport est positionnée à l'aide de lignes d'ancrage, la plate-forme et ses jambes passant librement au-dessus des têtes de piles.The transport barge is positioned using anchor lines, the platform and its legs passing freely above the pile heads.

Au moment de l'introduction de la barge, la distance (ou clair) entre l'extrémité inférieure de l'insert et la tête de pile est fonction de la marée, de l'amplitude des mouvements verticaux de la barge et de certains facteurs de sécurité. Cette valeur est désignée par AGo.When the barge is introduced, the distance (or clear) between the lower end of the insert and the pile head depends on the tide, the amplitude of the barge's vertical movements and certain factors of security. This value is designated by AGo.

L'ensemble barge de. transport/plate-forme étant positionné à l'aide des lignes d'ancrage, oscille, du fait de la houle, autour d'une position moyenne de coincidence parfaite entre piles et jambes.The whole barge of. transport / platform being positioned using the anchor lines, oscillates, due to the swell, around an average position of perfect coincidence between stacks and legs.

La barge de transport est dans un premier temps ballastée jusqu'à réduire le clair AGo à une valeur minimale compatible avec les mouvements verticaux de l'ensemble et de telle manière qu'il n'y ait pas de contact entre tête de pile et jambe de la plate-forme. C'est la position représentée dans la figure 1A.The transport barge is first ballasted until the clear AGo is reduced to a minimum value compatible with the vertical movements of the assembly and in such a way that there is no contact between pile head and leg of the platform. This is the position shown in Figure 1A.

Au cours d'une accalmie de houle, la coincidence verticale étant assurée pour un temps de l'ordre de la minute, des inserts sont largués simultanément et tombent dans les cônes de réception des têtes de piles, réalisant instantanément la connexion horizontale entre la plate-forme et la structure. On opère ce largage par manoeuvre simultanée des vérins correspondants 11. On pourra se contenter de larguer deux inserts ce qui suffit à assurer l'immobilisation horizontale de la plate-forme. Mais bien entendu on peut larguer plus de deux inserts simultanément et même la totalité d'entre eux. Le nombre d'inserts à larguer simultanément dépend de leur capacité et de celle des piles de la structure à supporter les efforts horizontaux engendrés par les trains de vagues. Leur nombre est de deux au minimum pour éviter toute rotation de la plate-forme qui pourrait se produire après connexion sur un seul insert et qui interdirait de descendre les autres dans les cônes récepteurs.During a swell lull, vertical coincidence being ensured for a time of the order of a minute, inserts are released simultaneously and fall into the cones of reception of the battery heads, instantly making the horizontal connection between the platform -form and structure. We operate this release by simultaneous operation of the corresponding cylinders 11. We can be content to drop two inserts which is sufficient to ensure the horizontal immobilization of the platform. But of course you can drop more than two inserts simultaneously and even all of them. The number of inserts to be dropped simultaneously depends on their capacity and that of the stacks of the structure to withstand the horizontal forces generated by the wave trains. Their number is at least two to avoid any rotation of the platform which could occur after connection on a single insert and which would prevent the others from going down into the receiving cones.

Une fois les inserts largués (figure 1B), l'ensemble barge- plate-forme reste libre de se mouvoir verticalement au gré de la houle, le long de l'insert. A titre de sécurité, la profondeur du cône de réception sera avantageusement prise au moins égale à la valeur du pilonnement maximal envisageable pour interdire tout déboitement accidentel d'un insert après connexion par frottement de l'insert à l'intérieur de la jambe, au moment du passage de trains de vagues.Once the inserts have been released (Figure 1B), the barge-platform assembly remains free to move vertically with the swell, along the insert. As a safety measure, the depth of the reception cone will advantageously be taken at least equal to the value of the maximum possible heave to prevent any accidental dislocation of an insert after friction connection of the insert inside the leg, at the moment of the passage of wave trains.

Le cône récepteur peut avantageusement être monté sur un amortisseur 14 en caoutchouc, élastomère ou tout autre matériau élastique approprié, pour amortir le choc créé par la chute de l'insert et assurer que celle-ci n'endommage pas la tête de pile de la structure, si le centrage de la plate-forme n'est pas parfait au moment du largage des inserts.The receiving cone can advantageously be mounted on a damper 14 made of rubber, elastomer or any other suitable elastic material, to absorb the shock created by the fall of the insert and to ensure that the latter does not damage the battery head of the structure, if the centering of the platform is not perfect when the inserts are released.

La dépose de la plate-forme sur la structure est ensuite réalisée par ballastage de la barge jusqu'à ce que le palonnier de la jambe de la plate-forme vienne en butée sur la tête de l'insert, la position relative jambe/insert étant redevenue la même qu'avant largage de l'insert (figure 1C).The removal of the platform on the structure is then carried out by ballasting the barge until the lifter of the leg of the platform comes into abutment on the head of the insert, the relative position leg / insert being again the same as before dropping the insert (Figure 1C).

Au cours de ce ballastage, les mouvements verticaux de la barge et de la plate-forme occasionnent des chocs entre le palonnier et l'insert, qui sont amortis par l'amortisseur intégré à l'insert.During this ballasting, the vertical movements of the barge and the platform cause shocks between the lifter and the insert, which are absorbed by the damper integrated into the insert.

La poursuite du ballastage de la barge permet ensuite de dégager la plate-forme de celle-ci, la plate-forme reposant en fin d'opération sur la tête de pile de la structure, par l'intermédiaire des inserts. La figure 1D montre l'écrasement de l'amortisseur en fin de ballastage.Continued ballasting of the barge then makes it possible to disengage the platform from the latter, the platform resting at the end of the operation on the pile head of the structure, by means of the inserts. Figure 1D shows the crash of the shock absorber at the end of ballasting.

La longueur de l'insert et l'emplacement du palonnier à l'intérieur de la jambe sont étudiés de manière à ce que la distance, en fin d'opération, entre extrémité inférieure de la jambe de plate-forme et la tête de pile de la structure soit suffisante pour permettre de souder deux demi-viroles métalliques (16A et 16B) qui assurent en finale la continuité de la structure installée entre pile et jambe de la plate-forme.The length of the insert and the location of the spreader inside the leg are studied so that the distance, at the end of the operation, between the lower end of the platform leg and the pile head of the structure is sufficient to allow two metal half-ferrules (16A and 16B) to be welded, which ultimately ensure the continuity of the structure installed between the stack and the leg of the platform.

On peut alors détruire l'amortisseur, par exemple par action chimique (figure 1E).We can then destroy the shock absorber, for example by chemical action (Figure 1E).

La hauteur de ballastage, c'est-à-dire la hauteur dont la barge doit pouvoir s'enfoncer pour permettre l'opération ci-dessus est au moins égale à la somme de quatre termes :

  • - la hauteur D correspondant à l'allègement du poids de la plate-forme,
  • - le clair initial AGo
  • --la valeur H du demi-pilonnement
  • - la profondeur h du cône de réception (h = 2H).
The ballasting height, that is to say the height which the barge must be able to sink to allow the above operation is at least equal to the sum of four terms:
  • - the height D corresponding to the reduction in weight of the platform,
  • - the initial clear AGo
  • --the H value of the half-heave
  • - the depth h of the reception cone (h = 2H).

Pour une barge de dimension 120 m x 30 m, supportant une plate-forme de 6000 tonnes, la hauteur d'allègement D est voisine de 2 mètres. Si le clair initial est de 0,6 mètre et le pilonnement de 0,9 m, la hauteur de ballastage est voisine de 4 mètres ; le ballastage nécessite alors une quantité d'eau très importante, de l'ordre de 13 000 tonnes.For a barge with a dimension of 120 mx 30 m, supporting a platform of 6000 tonnes, the relief height D is close to 2 meters. If the initial clear is 0.6 meters and the heaving 0.9 m, the ballasting height is close to 4 meters; ballasting then requires a very large quantity of water, of the order of 13,000 tonnes.

Une variante du système permet de réduire cette hauteur de ballastage ; cette variante s'appliquera de préférence aux très grosses plate-formes.A variant of the system makes it possible to reduce this ballasting height; this variant will preferably apply to very large platforms.

La variante repose sur la considération ci-après :

  • Immédiatement après le largage de l'insert 8, la distance entre le palonnier 7 de la jambe 6 et le sommet de l'insert est devenue :
    • AGo + h : H, H étant toujours le pilonnement de la barge.
The variant is based on the following consideration:
  • Immediately after the release of the insert 8, the distance between the lifter 7 of the leg 6 and the top of the insert became:
    • AGo + h: H, H being always the heaving of the barge.

Si on interpose alors, entre le palonnier et le sommet de l'insert, une cale d'épaisseur totale : (AGo + h - H), la hauteur du ballastage est réduite d'autant.If we then interpose, between the lifter and the top of the insert, a block of total thickness: (AGo + h - H), the height of the ballasting is reduced accordingly.

Dans l'exemple numérique considéré précédemment, le gain est de :

  • (0,60 + 0,90 - 0,45) = 1,05 m, soit plus de 25% sur la hauteur de ballastage.
In the digital example considered above, the gain is:
  • (0.60 + 0.90 - 0.45) = 1.05 m, i.e. more than 25% of the ballasting height.

Les figures 2A à 2E représentent la variante du dispositif de l'invention utilisant cette cale.FIGS. 2A to 2E show the variant of the device of the invention using this wedge.

La jambe est munie d'orifices 20A, 20B, 21A, 21B se faisant face deux à deux. La paire la plus basse est située à une distance maximale du palonnier telle que la distance entre le palonnier et la partie inférieure de la cale soit égale à d'= AGo + h - H, où ces symboles ont les mêmes significations que précédemment.The leg is provided with orifices 20A, 20B, 21A, 21B facing two by two. The lowest pair is located at a maximum distance from the spreader such that the distance between the spreader and the lower part of the wedge is equal to d '= AGo + h - H, where these symbols have the same meanings as before.

Comme le montre la figure 2C qui représente le dispositif au début de l'opération de ballastage, une cale 19 est introduite par une paire d'orifices (ici les orifices 21A, 21B inférieurs), de manière à servir de butée à l'insert en fin de ballastage (figure 2D).As shown in FIG. 2C which represents the device at the start of the ballasting operation, a shim 19 is introduced by a pair of orifices (here the orifices 21A, 21B lower), so as to serve as a stop for the insert at the end of ballasting (Figure 2D).

En fonction du niveau de la marée, de l'état de la mer au moment de l'opération, en particulier de la valeur du pilonnement, on choisit la paire d'orifices qui convient le mieux.Depending on the level of the tide, the state of the sea at the time of the operation, in particular the value of the heaving, we choose the pair of orifices which is best suited.

La figure 2E montre la position finale des divers éléments après soudage de deux demi-viroles 16A et 16B et destruction de l'amortisseur.FIG. 2E shows the final position of the various elements after welding of two half-ferrules 16A and 16B and destruction of the damper.

La cale est montée sur une glissière (non représentée) qui traverse la jambe de la plate-forme de manière à ne pas entraver le coulissement de l'insert - en passant, par exemple, de part et d'autre de l'insert à l'intérieur de la jambe -et est prolongée à l'extérieur de la jambe où la cale est en position d'attente avant la connexion.The wedge is mounted on a slide (not shown) which crosses the leg of the platform so as not to impede the sliding of the insert - passing, for example, on either side of the insert to the inside of the leg -and is extended to the outside of the leg where the wedge is in the waiting position before connection.

L'introduction de la cale à l'intérieur de la jambe peut s'effectuer manuellement ou à l'aide d'un dispositif mécanique comme par exemple un vérin (non représenté) dont la capacité requise se limite à la valeur du frottement dû au poids propre de la cale.The insertion of the wedge inside the leg can be done manually or using a mechanical device such as for example a jack (not shown) whose required capacity is limited to the value of the friction due to the dead weight of the hold.

Un intérêt supplémentaire de cette variante réside dans le fait que, après largage des inserts, la reprise des efforts horizontaux dûs à la houle induit des moments plus faibles dans les inserts, la distance entre le fond du cône de réception et le guidage 9 monté à l'extrémité inférieure de la jambe étant réduite par rapport au dispositif des figures 1A à 1E, d'une longueur égale à celle du dépassement de l'insert sous la jambe ; cette longueur peut attein- dre 1,5 mètres.An additional advantage of this variant lies in the fact that, after releasing the inserts, the resumption of the horizontal forces due to the swell induces smaller moments in the inserts, the distance between the bottom of the reception cone and the guide 9 mounted at the lower end of the leg being reduced relative to the device of FIGS. 1A to 1E, by a length equal to that of the protrusion of the insert under the leg; this length can reach 1.5 meters.

Claims (10)

1/ Jambe d'une plate-forme marine s'engageant sur une pile qui appartient à une structure fixe dont la tête présente un cône récepteur, ladite plate-forme présentant des jambes en nombre égal aux piles chaque jambe étant destinée à être fixée à une pile, ladite jambe étant creuse et enfermant un insert pouvant coulisser dans la jambe et destiné à solidariser la jambe et la pile correspondante par son introduction partielle dans le cône récepteur, caractérisé en ce que l'insert (8) est associé à un moyen (10, 11) qui permet de le solidariser à la jambe et de le désolidariser brusquement, provoquant la chute de l'insert par gravité.1 / Leg of a marine platform engaging on a pile which belongs to a fixed structure whose head has a receiving cone, said platform having legs equal in number to the piles each leg being intended to be fixed to a stack, said leg being hollow and enclosing an insert which can slide in the leg and intended to secure the leg and the corresponding stack by its partial introduction into the receiving cone, characterized in that the insert (8) is associated with a means (10, 11) which makes it possible to secure it to the leg and to detach it suddenly, causing the insert to fall by gravity. 2/ Jambe selon la revendication 1, caractérisé en ce que le moyen comprend au moins un doigt (10) traversant la jambe (6) et coopérant avec un alésage de l'insert.2 / leg according to claim 1, characterized in that the means comprises at least one finger (10) passing through the leg (6) and cooperating with a bore of the insert. 3/ Jambe selon la revendication 2, caractérisé en ce que le doigt (10) est associé à un vérin (11).3 / leg according to claim 2, characterized in that the finger (10) is associated with a jack (11). 4/ Jambe selon l'une des revendications 1 à 3, caractérisé en ce qu'elle comporte au moins une paire d'orifices (21A, 21B) pour l'introduction d'une cale (19) limitant la course de l'insert.4 / Leg according to one of claims 1 to 3, characterized in that it comprises at least one pair of orifices (21A, 21B) for the introduction of a shim (19) limiting the stroke of the insert . 5/ Dispositif selon l'une des revendications 1 à 4, caractérisé en ce que l'insert (8) est constitué de deux parties tubulaires coaxiales (8A, 8B) fixées chacune par une extrémité à un même bloc amortisseur (14).5 / Device according to one of claims 1 to 4, characterized in that the insert (8) consists of two coaxial tubular parts (8A, 8B) each fixed at one end to the same damping block (14). 6/ Dispositif selon la revendication 5, caractérisé par le fait que le bloc amortisseur est du type détruisible.6 / Device according to claim 5, characterized in that the damping block is of the destroyable type. 7/ Procédé de mise en place d'une plate-forme sous-marine portée par une barge et comportant au moins deux jambes selon la revendication 1, sur une structure fixe, caractérisé en ce qu'il comprend les phases suivantes : a/ on approche la barge (2) de la structure de manière à mettre les jambes (6) au-dessus des têtes de piles (4) b/ on désolidarise brusquement au moins deux inserts de leur jambe respective par action simultanée des moyens (10, 11) de solidarisation correspondants. c/ on balaste la barge (2) jusqu'à permettre son éloignement de la structure d/ on effectue la liaison définitive entre chaque jambe et la pile correspondante. 7 / A method of setting up an underwater platform carried by a barge and comprising at least two legs according to claim 1, on a fixed structure, characterized in that it comprises the following phases: a / we approach the barge (2) of the structure so as to put the legs (6) above the pile heads (4) b / at least two inserts are suddenly separated from their respective legs by simultaneous action of the means (10, 11) of corresponding securing. c / the barge (2) is ballasted until it is distant from the structure d / the final connection is made between each leg and the corresponding stack. 8/ Procédé selon la revendication 7, caractérisé en ce qu'entre les phases c/ et d/ on insère dans chacune des jambes concernées une cale (19) traversant la jambe au-dessus de l'insert par des orifices (21A, 21B) se faisant face deux à deux.8 / A method according to claim 7, characterized in that between phases c / and d / is inserted into each of the legs concerned a wedge (19) crossing the leg above the insert through holes (21A, 21B ) facing two by two. 9/ Procédé selon l'une des revendications 7 et 8, caractérisé en ce qu'après la phase e/, on détruit le bloc amortisseur.9 / A method according to one of claims 7 and 8, characterized in that after phase e /, the shock absorber block is destroyed. 10/ Procédé selon l'une des revendications 7 à 9, caractérisé en, ce que la phase e/ est une phase de soudage avec apport éventuel, pour chaque couple jambe-pile, de deux demi-viroles métalliques.10 / A method according to one of claims 7 to 9, characterized in, that the phase e / is a welding phase with possible addition, for each leg-stack pair, of two metal half-ferrules.
EP82104068A 1981-05-15 1982-05-11 Leg of an offshore platform and method of placing it Expired EP0065695B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8109708A FR2505900A1 (en) 1981-05-15 1981-05-15 DEVICE FOR PLATFORM PLACEMENT AND METHOD OF USING THE DEVICE
FR8109708 1981-05-15

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EP0065695A1 true EP0065695A1 (en) 1982-12-01
EP0065695B1 EP0065695B1 (en) 1985-02-06

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US (1) US4413926A (en)
EP (1) EP0065695B1 (en)
JP (1) JPS57193619A (en)
DE (1) DE3262205D1 (en)
FR (1) FR2505900A1 (en)
NO (1) NO155783C (en)

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WO1987004742A1 (en) * 1986-02-04 1987-08-13 Riles William G Offshore platform construction including preinstallation of pilings

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JPS6336462A (en) * 1986-07-31 1988-02-17 Pfu Ltd Serial data receiving circuit
US4848967A (en) * 1988-01-04 1989-07-18 Exxon Production Research Company Load-transfer system for mating an integrated deck with an offshore platform substructure
US4930938A (en) * 1989-06-02 1990-06-05 Exxon Production Research Company Offshore platform deck/jacket mating system and method
US5447391A (en) * 1993-09-30 1995-09-05 Shell Oil Company Offshore platform structure and system
US5445476A (en) * 1993-09-30 1995-08-29 Shell Oil Company Reusable offshore platform jacket
US5431512A (en) * 1993-12-28 1995-07-11 Mcdermott International, Inc. Flex tube compliant offshore structure
AU685637B2 (en) 1994-05-02 1998-01-22 Shell Internationale Research Maatschappij B.V. A method for templateless foundation installation of a TLP
US5593250A (en) * 1994-12-23 1997-01-14 Shell Offshore Inc. Hyjack platform with buoyant rig supplemental support
US5551801A (en) * 1994-12-23 1996-09-03 Shell Offshore Inc. Hyjack platform with compensated dynamic response
US5741089A (en) * 1994-12-23 1998-04-21 Shell Offshore Inc. Method for enhanced redeployability of hyjack platforms
US20100316450A1 (en) * 2007-12-21 2010-12-16 Vestas Wind Systems A/S Method for installing an offshore wind turbine and a barge system
US8926225B2 (en) * 2013-03-18 2015-01-06 J. Ray Mcdermott, S.A. Leg mating unit

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WO1987004742A1 (en) * 1986-02-04 1987-08-13 Riles William G Offshore platform construction including preinstallation of pilings

Also Published As

Publication number Publication date
DE3262205D1 (en) 1985-03-21
FR2505900B1 (en) 1984-10-26
NO155783C (en) 1987-05-27
JPS57193619A (en) 1982-11-29
JPS6130086B2 (en) 1986-07-11
EP0065695B1 (en) 1985-02-06
US4413926A (en) 1983-11-08
NO155783B (en) 1987-02-16
NO821592L (en) 1982-11-16
FR2505900A1 (en) 1982-11-19

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