FR2472631A2 - Oscillatable permanent marine installation - has steel lattice shaft connected to base by spherical pivot joint - Google Patents

Abstract

An oscillatable marine installation comprises a concrete and steel lattice shaft supported by a demountable pivot joint on a base fixed to the sea-bed and including an anti-torque device. The pivot joint is made up of three parts a casing fixed to the shaft, a part-spherical housing fixed to the base, and a pivot member. The pivot member has an upper part cooperating with the casing, a flange which can be fixed to the casing, and a lower part-spherical part which supports a resilient assembly and a bush. The bush is fixed on the housing. The anti-torque device comprises a universal joint, concentric with the pivot joint. Two opposite pivots of the cross-piece of the universal joint are supported by the lower part of the shaft and the other two pivots by the base. At least two opposite pivots have damping devices. The pivots supported by the base are mounted on supports of adjustable.

Description

 This certificate of addition concerns, like the main patent, an oscillating structure and, more particularly, a platform to be installed in a fixed site, at sea or in a body of water and which can be used for different uses, such as storage of materials, drilling work, etc ...

 This work comprises a barrel resting on a base fixed on the bottom, which supports, at its upper part, the platform proper or bridge, the barrel having a sufficient height so that the bridge is always above the water level .

The barrel is connected to the base by a spherical articulation allowing it to oscillate in all directions under the action of the swell, and is ballasted near its base so that the weight of the whole ballast, of the barrel, of the bridge and of the masses which it carries is greater than the maximum ascending force due to the buoyancy of Archimedes and to the action of the elements, and that thus the spherical joint is always in compression.

In the main patent, as well as in the additions, a barrel consisting of a sealed hollow column capable of receiving a ballast at its lower part was considered, while the upper part constitutes a float. Such an embodiment is well suited to a relatively low structure. But the higher the height, the more the bole tends to resonate with the swell. To avoid this drawback, elements of different stiffness are inserted.

The float portion of the cylindrical drum structure is particularly vulnerable near the surface where it risks being damaged by ships coming to moor. Despite the division of the volume into compartments, any waterway in a compartment produces a relatively large deposit of the structure and in any case inadmissible for the drilling tubes.

The movements of the platform subject the drilling tubes, generally arranged at the periphery of the barrel, to increasing bending stresses with its distance from the axis of the column, the greater the distance between the base of the barrel and the base is weak.

 United States Patent No. 3,670,515 has provided a solution to this problem. It describes an oscillating platform for drilling made up of a barrel formed of a lattice structure having at its upper part a float. The end of the barrel is connected to the base, held by piles in the underwater soil, via a joint. The drill pipes descend along the barrel and outside where they are guided by supports. In order to avoid excessive bending of the tubes in line with the articulation, the latter carries in the plane of the articulation a support device connected to the barrel and to the base by articulated bars allowing the tubes to slide freely. Such a device requires sufficient free lengths of tube, so that the stresses can be distributed and avoid exceeding the elastic limit of the metal.

The articulation, subject of the main patent, is of a different type from that described above, and the invention relates to new means capable of limiting the heel of the platform in the event of a waterway in the float, Decrease the bending angle of the drilling tubes while protecting them against shocks and currents and keep the tubes under constant tension whatever the movements of the cut.

 In order to allow the installation of the structure whatever the cohesion of the underwater soil, new means are used to make and maintain the base.

 The realization of a joint comprising an elastic lining could only be envisaged as a whole and required construction on site. In addition, the articulation had to be fixed to the barrel and the base before the installation of the structure on the site. Maintenance was then very difficult and the change of lining hardly possible. The invention proposes to provide a lining joint which can be put in place and changed without difficulty, even after installation of the structure on site.

 The explanations and figures given below by way of example will make it possible to understand how the invention can be implemented.

Figure 1 is a partial sectional view of a work according to the invention.

 FIG. 2 is a section on II II of FIG. 1.

Figure 3 is a section on III III of Figure 1.

 Figure 4 is a section on IV IV of Figure 1.

FIG. 5 is a section along V V of FIG. 1.

 Figure 6 is a section along VI VI of Figure 1.

 Figure 7 is a view of the tube holding means.

Figure 8 is a sectional view of an embodiment of a removable joint.

FIG. 9 is an exploded view in section of the joint of FIG. 8.

Figure 10 is a sectional view of another embodiment of a removable joint.

FIG. 11 is a view of a lining along XI XI of FIG. 8.

 FIG. 12 is a view of another embodiment of the lining according to XII XII of FIG. 10.

Figures 13 to 18 show different stages of disassembly of a joint according to the invention.

Figures 19 to 22 show different stages of reassembly of a joint.

 FIGS. 23 to 30 show the phases of the construction and of the setting up of a structure with a removable articulation and a truss base.

 Figures 31 to 34 show the final phases of the construction and installation of a weight-based structure.

 FIG. 1 partially shows in section an oscillating structure comprising a base 1 resting on the underwater ground 2. A barrel 3 is supported on this base by a spherical articulation 4. The barrel is made up of a structure 5 of wire mesh whose lower part is designed to form a capacity 6 capable of receiving ballast, and the upper part a honeycomb structure 7 of the float. The top of the barrel supports the bridge 8 on which are fixed the operating and housing modules 9 and the drilling derrick 10. According to the embodiment shown, the barrel has a reduced diameter in its part 12, part of which is submerged to reduce the catch from surface currents. According to a characteristic of the invention, the honeycomb structure 7 is formed in its upper part 12 of volumes 13 made up of leaktight elements at least partially cylindrical (FIG. 2).

These elements 13 have one of their walls defined by the cylindrical surface 14. Inside this surface 14 are regularly distributed portions of cylindrical surface 15. These cylindrical surfaces 15 extend over the entire height of the float 7 and form below part 12 of the cylindrical volumes 16. The outer cylindrical wall. 14 rests on the cylindrical elements 16 arranged side by side along, for example, a circumference to form a closed geometric figure.

 The structure of the float is preferably made of concrete using, for example, the sliding formwork technique. The cylindrical elements 16 are held together by tangential connections 17 and are compartmentalized by watertight partitions 18 perpendicular to their axis. The rigidity of the structure is obtained by radial partitions 19 which divide the interior volume 20 in the longitudinal direction, and are based on the tangential connections 17. FIG. 3, corresponding to section III III d @ of the alveolar float structure, shows the means of connecting the pillars 21 of the wire mesh structure to the concrete float structure. Housing 22 is provided in the bottom 23 of the float to receive and hold the ends of the pillars. According to the embodiment shown, the metal trellis structure 5 consists of six pillars 21 braced to each other and diametrically (FIG. 4).

 The lower capacity 6, capable of receiving a solid or liquid ballast, consists of sections of tubes 24 placed side by side along the sides of the hexagon formed by the six pillars 21 (fig. 5). This structure is preferably metallic , but can also be made of concrete tubes. It is also a honeycomb structure that can be used as a float when the barrel is put in place (this use will be described later).

 The barrel, previously described, rests by means of an articulation 4 on a weight base, of a type similar to that described in the main patent and schematically represented in FIG. 19, comprising a partitioned volume 25 receiving the ballast and at the center of which is fixed part 26 of the joint.

Such a base is preferably reserved for an underwater soil having good cohesion and whose mud layer is sufficiently weak. When the structure is to be installed on particularly unstable soil with large mud thicknesses, a truss base is used which can be fixed in the solid basement by piles of suitable length. In the conventional technique, the base is nailed by piles in a relatively small number, owing to the limited dimensions of the base and its use on soils with a great thickness of mud is fairly uncertain. According to a characteristic of the invention, barrels 27 (fig. 6) are provided at the periphery of the base. These barrels are uniformly distributed, according to the embodiment, at the tops of the base and are made up of groups of vertical tubes 28 capable of receiving piles 29. The tubes are fixed in bores provided in two discs 30 and 31, spaced apart, welded to the lattice structure of the base (fig. let 7). According to a known method, the piles 29 are driven into the tubes 28 and their ends are joined at 32. To avoid excessive stresses on the drilling tubes, as a result of the oscillating movements of the platform, the drilling tubes are passed through the free internal volume 20 as well as through the trellis barrel and into space 20 A from the base. The tubes are close to the axis of the platform and the flexions are very reduced at the level of the Afin articulation. 1, 2, 6).

Figure 2 shows the distribution of the tubes in the cells formed by the longitudinal partitions in the volume 20. In order to avoid deformation of the tubes, they must be supported and to compensate for their weight, the current technique consists in exerting traction at their end by means of bellows devices of modifiable length, such as those described, for example, in the patent of
United States of America 3,677,016. This device requires the use of fairly complicated equipment so that the tubes located on the side where the platform slopes, do not undergo excessive compression and that those placed on the opposite side are not stretched too much. The invention proposes a new method consisting in using the Archimedes thrust to transmit the necessary traction to the tubes. According to one embodiment of the invention shown in FIGS. 1 and 7, the drilling tube 33 is fixed to the at least in its part passing through the float 7, annular floats 34. Guide means are provided so that the tube can move freely in the longitudinal direction. They consist, for example, of collars 35 integral with the thread in which the drilling tubes 33 slide and are preferably used when the interior volume 20 is in communication with the exterior. Communication is ensured, for example, by piercing the bottom of the interior volume of the honeycomb structure. The passages thus formed are large enough to allow free passage of the tube 33 and possibly of the floats 34. According to another embodiment of the guide means, they are formed by wells 36 partially occupying the free internal volume 20, provided during construction of the float 7. Only the wells are in communication with the sea and their diameter is sufficient to allow the free movement of the floats in the longitudinal direction, as shown in FIG. 70
Due to the high security of the device for tensioning the drilling tubes, the well heads 37 are placed on the deck, (free to move relative thereto), which greatly facilitates the maintenance operations of production set0
The semi-spherical joint, described in the main patent, comprises an elastic lining consisting of an alternating stack of layers of elastomer and of sheet metal interposed between two metal frames. The seal has a lifespan of 30 years, but if we wanted to extend this duration or dismantle the installation, a procedure was provided for the removal and also the replacement of said seal. According to a characteristic of the invention, the joint has been made removable. FIG. 8 shows a section of an exemplary embodiment of a removable articulation. This consists of at least three parts: a first part 38 integral with the ffit 3, consisting of a metal jacket 39 at least partially conical fixed by external ribs 40 at the base of the concrete to be made, or welded to the end of the trellis structure and carrying at its periphery a flange 41 a second part 42 consisting of a spherical cap 43 carrying at its periphery a flange 44, fixed to the base 45 of concrete or wire mesh a third part 46 forming a pivot and cooperating directly or indirectly with the first and second parts. The pivot has an upper conical portion 47 of shape approximately complementary to that of the jacket 9 in which it is housed.

The part 47 is limited by a flange 48 which is fixed on the flange 41 by bolts, In order to allow, in the case of a concrete fAt, access to the rear of the flange, a bowl 49 is provided. The lower part 50 has a cylindrical-spherical shape on which the first metal frames 51 of the elastic lining portions 52 are fixed.

The second metal frames 53 are fixed in a shell 54 with a radius less than the radius of the spherical cap 43 fixed to the base. The shell carries on its peripheral edge a flange 55 capable of being fixed by known means on the flange 44 carried by the cap 43o
According to the particular embodiment of Figures 8 and 9, the second frames 53 of the lining portions 52 are held in a cage 56. This cage is welded to the shell 54 by openings 5? The edges of the cage cannot be welded and are blocked by a ring 58 which is fixed on the flange 55 of the shell. In order to protect the joint and more particularly the linings, a flexible sealing member 59 is provided between the lower part 50 of the pivot and the ring 58. The lining portions 52 are of prismatic or cylindrical shape ending in two caps spherical, one convex and the other concave.

The spaces 60 and 61, respectively between the jacket 39 and the upper part 47 of the pivot and between the spherical cap 43 and the shell 54, receive an injection of a cement grout, which simplifies and facilitates the production of the concentric elements and the transmission of forces between the different elements. This joint can however title undone to allow the separation of the elements when desired.

Another embodiment of a removable joint is shown in Figure 10o. Elements similar to those of the previous embodiment bear the same references. Part 50A carrying the packing portions is partially spherical, the center 0 being inside the joint 0
The edge of the semi-spherical cap 43 is extended by a cylindrical portion 62 on which the flange 44 is fixed. The shell 54 follows above the center 0 the spherical curvature and leaves between it and the cylindrical extension 62 of the cap a space 65 has both a corner section. This space can partially be occupied by a ring 64 fixed to the outer edge of the shell,
In the previous examples of removable articulation, the elastic packing was in the form of packing portions. This shape has the advantage of allowing better cooling necessary when the weights supported in oscillation are significant. According to one embodiment, the deformable lining (FIG. 11) consists of lateral polyhedral spherical ribs 65, arranged between the convex surface of the pivot and the concave surface of the cap, starting from the edges and going towards the bottom and d '' a central polyhedral spherical cap 66 disposed at the bottom.

According to another embodiment shown in Figure 12, which is a view along X II of Figure 10 after removing the pivot 50Â, the lining consists of lateral portions of spherical sectors 67, 68 disposed between the convex surface of the pivot and the concave surface of the cap starting from the edges and going towards the bottom and of a central spherical cap 69 arranged at the bottom,
The joint, shown in Figure 8, is equipped with a packing of the type corresponding to that described with reference to Figure 11 which is a view along
Il of FIG. 8 (the pivot not being shown) and that of FIG. 10, of the type described with reference to FIG. 12, seen along XII XII of FIG. 10.

The method of disassembly and reassembly of a joint according to the invention is shown in Figures 13 to 18 and 19 to 22o
Prior to dismantling the joint, the oil production wells are stopped and the part of the tubes 3 "in FIG. 7 comprised between the well head 37 and the underwater ground 2 is dismantled.

Then the disassembly of the articulation is carried out according to the following operations: the connection between the upper part of the pivot 47 and the liner 39 is removed; to do this, we dismount the bolts fixing the flange 48 of the pivot to the flange 41 of the liner (Figure 13). We separate the pivot of the shirt (Figure 15) by reducing the ftt by deballasting floats 6 and 70 We completely disengage the upper part of the pivot from the shirt (Figure 16) and we move the fAto laterally We hook the pivot to means lifting and removing the connection between the flange 55 of the shell 54 and the flange 44 of the cap 43 fixed to the base (Figure 17). The pivot and its lining are hoisted. Figure 18 illustrates this last operation and shows the respective positions of the platform and the base.

The efforts to be exerted to take off the pivot of the shirt and, in particular, to overcome the friction resistance between the cement joint and the wall of the shirt covered during the assembly of a release product, would risk producing a backing. around the trim. To avoid such a drawback, there are between the flange 48 of the pivot and the flange 55 of the shell bracing means 70 (FIG. 14) which transmit the forces to the shell without risk for the lining.
The detachment of the pivot of the shirt by the sole deballasting of the barrel is a delicate operation whose control is difficult. In order to perfectly counter this operation, the process is modified as follows: pushing means 71 (FIG. 13), such as jacks, are installed between the pivot and the liner and, more particularly, between the flange 48 of the pivot and the flange 41 of the shirt. The jacks are arranged between the bracing means 70o. Suppress (FIG. 14), if this operation has already been done, the connection between the flange 48 and the flange 41o. The jacks are actuated so that the total force developed by the jacks is higher than that due to the assumed initial resistance and the fbt is lightened (FIG. 15) until the cement joint occupying the space 60 is broken. At this time, the ftt is not yet in floatation, but still rests on the joint. The rupture of the cement joint is indicated by the pressure drop in the cylinders. The rest of the operations take place in the manner previously described.

For reassembly of a new articulation, the procedure is shown schematically in Figures 19 to 22. elements similar to those previously described have the same references. The new pivot, equipped with bracing means 70, is suspended from the lifting means, lowered and positioned so that the shell 54 comes to be placed in the cap 26 fixed to the base 25 (Figure 19). The flange 55 of the shell is fixed on the flange 44 of the cap, the lifting means are removed and a cement grout is injected through injection points not shown in the space 61 between the shell and the cap (Figure 20) .On position above the pivot the fAt carrying the shirt 39 (Figure 2l) .We ballast the fbt so that the shirt comes to cover the pivot (Figure 22). The flange 48 of the pivot is fixed to the flange 41 of the liner and a cement grout is injected between the upper part of the pivot and the liner in the space 60 (Figure 22). We then dismantle the bracing means 700
The method of construction and installation of the oscillating structure, according to the invention, comprises the following operations: the base or bottom of the alveolar structure of the float, which is mounted up to, is constructed on the ground or in a floating dock at a sufficient height to ensure its buoyancy0 Simultaneously, we proceed with the construction of the wire mesh structure of the ftt and the base. We start the base 72 of the floats (Figure 23) and complete the honeycomb structure of the float 73 afloat by, for example, the sliding formwork method (Figure 24). float 73 according to the known method of ballasting the float (figure-25) 0 The cells 74 to 77 of the float are ballasted (figure 26a) so as to lay 11 float 73 and bridge 74 assembly horizontally and at the surface (figure 26b). The lattice structure 78, the end of which carries the pivot and the linings 79, is brought to a horizontal position (FIG. 27). The float 73 and the lattice structure 78 are assembled to the right of the housings. 22 (see FIG. 3) and the assembly is towed to the site (FIG. 28) Ballasting of the capacities 6 of the lower part 80 of the structure 78 is carried out to place the platform in the vertical position (FIG. 29) The platform is positioned above the base 81 previously installed, the pivot is lowered in its place, that is to say that the shell is positioned in the cap fixed to the base. We proceed to their fixing which includes the bolting of the collar of the shell on the flange of the cap and 11injection of a cement grout between them, we dismantle the bracing means, we proceed to the installation of modules 82 on the bridge (figure 30).

 This process is particularly suitable for a structure with a metal lattice base, this base requiring its prior fixing to the ground by piles.

 When using a weight base, you can do the same. It is however possible, with the dismountable joint, to use the process which will be described below and which has the advantage of not requiring the float to be laid down nor of using high capacity crane barges.

As in the previous method, the base of the honeycomb structure of the float 73 and of the base 83 and the wire mesh structure 78 are constructed simultaneously on land.

 The construction of the weight base is similar to that of the float structure. The float base and the base are launched, the completion of which is done afloat. The deck 84 comprising the modules and the derrick is placed on the float 73 and it is towed to the site (Figure 31). The wire mesh structure 78 is floated to which the base 83 is fixed by means of the articulation 85 and bracing means (not shown), it is towed to the site (FIG. 32). As the weight base includes floats, its positioning at the end of the ftt wire mesh structure can be similar to the technique used to assemble, in the previous process, the float to the structure (Figures 27 and 28 ) o The pivot, held by the bracing means, will be housed in the shirt worn by the ftt. The same operations for fixing and forming a joint by injection of cement, described in the preceding process, are carried out. The trellis structure 78 and the base 83 are ballasted to bring them to the vertical position on the site (FIG. 33 ).

Position the float 73 carrying the bridge 84 above the structure 78 and ballast it to make it rest on the pillars of the structure to which it is fixed (Figure 34) o

Claims (11)

REVEEDICAXIONS 1. Oscillating structure according to claim 1 of the main patent, characterized in that the fît consists of a wire mesh structure (5) resting by the articulation (4) on the base (1) and connected to its part greater than at least one alveolar float structure (7).  2. Oscillating structure according to claim 1, characterized in that the alveolar float structure consists of at least partially cylindrical elements (13) arranged side by side in a closed geometric figure. 3. Oscillating structure according to claim 2, characterized in that the at least partially cylindrical elements are fixed to each other by tangential connections (17) and in that the internal volume (20) defined by the at least partially cylindrical elements carries radial partitions (19) leading to tangential connections (17). 4. Oscillating structure according to claim 2 or 3, characterized in that the at least partially cylindrical elements carry watertight partitions (18) perpendicular to their axis.  5. Oscillating structure according to one of claims 2 to 4, charac terized in that the at least partially cylindrical elements (13) are sealed from one another.  6. Oscillating structure according to one of the preceding claims, characterized in that the metal trellis structure carries near its base a honeycomb float structure (6) made up of at least partially cylindrical elements capable of receiving a ballast, 7. Oscillating structure according to one of the preceding claims, characterized in that the base serving to support the structure on the seabed consists of a lattice structure and carries barrels (27) integral with it at its periphery. of the structure made up of groups of vertical tubes (28) capable of receiving piles (20) e  80 oscillating structure according to one of the preceding claims, characterized in that oil drilling (33) is provided in the free central part between the elements constituting the floats  90 oscillating structure according to claim 8, characterized in that the drilling tubes (33) carry, at least in the part situated between the floats, annular floats (34), guide means (35) holding the tubes freely between the floats. 10th oscillating structure according to claim 9, characterized in that the guide means (35) consist of wells (36) provided in the central part of the alveolar float structure.  11. Oscillating structure according to claim 9 or 10, characterized in that the well heads (37) are slidably mounted on the structure and placed in the open air. 12th oscillating work according to claim 9 of the main patent and one of the preceding claims, characterized in that the deformable lining consists of lateral polyhedral spherical caps (65) disposed between the convex surfaces of the pivot (50) and concave of the cap (42) from the edge of the surfaces going towards the bottom and a central polyhedral spherical cap (66) arranged at the bottom.  13. Oscillating structure according to claim 9 of the main patent and one of the preceding claims, characterized in that the deformable lining consists of portions of lateral spherical sectors (67,68) disposed between the convex surfaces of the pivot and concave of the cap, from the edge of the surfaces towards the bottom and a central spherical cap (69) disposed at the bottom. 14. Oscillating structure according to claim 1 of the main patent and one of the preceding claims, characterized in that the articulation is removable and consists of at least three parts, a first part integral with the barrel (38), a second part (43) integral with the base and a third part (50) comprising at least one pivot cooperating directly or indirectly with the first and last parts  15. Oscillating structure according to claim 14, characterized in that the third part carries the deformable lining (52) o 16. Oscillating structure according to claim 15, characterized in that the first part (38) consists of a jacket (39) at least partially conical; in that the second part (42) consists of a spherical cap (43) carrying at its periphery a flange (44); and in that the third part (46) forms a pivot carrying a collar (48) delimiting an upper part cooperating with the jacket and having an approximately complementary shape, and a cylindrical-spherical lower part (50) on which the first are fixed reinforcements (51) of the deformable lining portions (52), the second reinforcements (53) being fixed in a shell (57) of radius smaller than the radius of the cap (49) and carrying on its edge a flange (55), said flange being capable of being fixed on a corresponding flange (44) integral with the cap (43) fixed on the base,  17. Oscillating structure according to claim 16, characterized in that the second frames (53) of the deformable lining portions (52) are fixed in a cage (56) held at least by a ring (55) cooperating with its edge and capable of to be fixed on the flange (55) of the shell (54) o  18th Oscillating work according to claim 16 or 17, characterized in that a flexible sealing member (59) is provided between the collar of the shell and the pivot.  19. A method of dismantling a joint according to one of claims 14 to 18, mounted on an oscillating structure, characterized in that: a) the connection between the upper part of the pivot and the sleeve is removed; b) the pivot and the shell are braced and the upper pivot part of the liner is separated at least by deballasting the socket; c) the upper part of the sleeve pivot is completely released; d) the fit is moved laterally with the bridge; e) the pivot is hooked to lifting means f) the connection between the shell and the cap is removed; g) the pivot and the deformable lining are hoisted  20.Process according to claim 19 characterized in that between phases a) and b) is installed thrust means between the pivot and the jacket and bracing means between the pivot and the collar of the shell and in that during phase b), the upper part of the sleeve pivot is separated by actuation of the pushing means and lightening of the fit0  21st Method for setting up an articulation according to one of claims 14 to 18, the fit and the base respectively carrying the shirt and the cap, characterized in that a) the pivot is suspended from the means of lifting, the bracing means being arranged between the pivot and the collar of the shell; b) the pivot is lowered and the shell is placed in the cap; c) the shell flange is fixed to the flange of the cap; d) the lifting means are lifted; e) a grout is injected between the shell and the cap; f) one brings above the pivot the fit wearing the shirt; g) bal laste made it so that the shirt comes hairdresser the pivot; h) the flange of the pivot is fixed to the liner by means of the flanges; i) a grout is injected between the shirt and the upper part of the pivot; j) dismantling the bracing means0  220 A method of constructing and installing an oscillating structure according to one of the preceding claims, characterized in that the base of the alveolar float structure and the wire mesh structure are constructed simultaneously on the ground, launching of the base and completion of the float afloat, we proceed with the installation of the bridge, we ballast the alveoli of the float to layer horizontally on the surface the float and the bridge, we bring the lattice structure to the horizon position " tale, said structure being fitted with the pivot and the lining, they are connected, the assembly is towed on site, ballasted in an upright position and assembled and positioned above the em- base previously installed on the bottom, we proceed to the establishment of the pivot and, in particular, by the ballasting of the barrel, the rascal is fixed in calotl; e shell in the calottf carried by the base, we dismantle the means of bracing, we proc proceeds to the installation of the modules on the bridge.  23o A method of constructing and setting up an oscillating structure according to one of claims 1 to 6 and 8 to 21, characterized in that the base of the alveolar structure of the float and the base is simultaneously constructed and the wire mesh structure, we launch the base of the float and ltemba e and the completion of the float and the floating base, we fix on the float the bridge, the modules and the derrick, we launches the metallic lattice fit structure to which the base is fixed via the joint, it is towed to the site, the metallic lattice structure is immersed on the site, the float is positioned bearing the bridge over the metal trellis structure, we put it on the structure by ballasting, we fix the float to the trellis structure0