Manufacturing method of floating foundation

Abstract

To provide a manufacturing method of a floating foundation which can realize efficient manufacturing of a concrete floating foundation in a dock.SOLUTION: A manufacturing method of a semi-submersible foundation 70 (a floating foundation) includes: a step in which a center column foundation 71, side column foundations 73, and pontoons 70C are manufactured; a step in which the center column foundation 71 and the pontoons 70C are transported to a connection yard 20 and one end of each pontoon 70C is connected to the center column foundation 71; a step in which each side column foundation 73 is transported to the connection yard 20 and the other end of the pontoon 70C is connected to the side column foundation 73; a step in which a center tower 72 is connected to the center column foundation 71; and a step in which a side tower 74 is connected to each side column foundation 73.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for fabricating a floating foundation. [Background technology]

[0002] Demand for renewable energy sources is increasing with the aim of reducing greenhouse gas emissions. Renewable energy sources include solar power, wind power, hydroelectric power, geothermal power, and biomass. Wind power generation facilities are often installed in mountainous areas away from residential areas, as the noise and vibrations from the wind turbines can have an impact on living environments and the impact on living spaces must be fully considered. However, it is difficult to secure land in mountainous areas for installing large wind turbines, and it is also difficult to secure transportation routes to wind power generation facilities and install transmission lines, etc., so technological development is underway to install offshore wind turbines that make up wind power generation facilities on the sea (including on water or lakes). When constructing offshore wind turbines on the sea, floating foundations are sometimes used as the foundations. Floating foundations include semi-submersible, spar, purge, and TLP (Tension Leg Platform) types. Among these, semi-submersible foundations (semi-submersible floating foundations) have a center column that supports the wind turbine tower (support), multiple (3 or 4) side columns spaced around the center column, and pontoons that connect the center column and side columns.They have a relatively proven track record as they provide excellent stability against waves and sea breezes.

[0003] Conventional floating foundations are generally made of steel, which has led to rising manufacturing costs, and this problem becomes even more pronounced as the size of the floating foundations increases. Therefore, while it is possible to reduce production costs by fabricating a concrete floating foundation in a dock and towing it out to sea for installation, there is currently no established efficient method for fabricating a concrete floating foundation in a dock, and therefore a method for fabricating a floating foundation that allows for efficient fabrication is desired.

[0004] Patent Document 1 proposes a tower assembly method in which the tower of an offshore wind turbine is divided vertically into multiple tower components, which are then assembled on a jack-equipped platform constructed on a base that is installed on the ground. Patent Document 2 proposes an installation method for offshore wind turbines in which the tower of the offshore wind turbine is divided vertically into multiple tower components that are assembled and installed offshore.This installation method includes a caisson installation process in which a caisson, which forms the base of the offshore wind turbine, is installed at the installation location of the offshore wind turbine, an assembly process in which multiple tower components are assembled in the caisson, and a blade installation process in which blades are attached to a nacelle attached to the topmost tower component in the caisson. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-80852 [Patent Document 2] Patent Publication No. 2021-76043 Summary of the Invention [Problem to be solved by the invention]

[0006] Although the above-mentioned Patent Documents 1 and 2 describe an efficient tower assembly method, they do not describe a technique for efficiently fabricating a floating foundation made of concrete in a dock.

[0007] An object of the present invention is to provide a method for manufacturing a floating foundation that can realize efficient manufacturing of a concrete floating foundation in a dock. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a method for manufacturing a floating foundation that supports the tower of an offshore wind turbine, the floating foundation being a semi-submersible foundation comprising a concrete center column, a plurality of concrete side columns that are arranged at intervals in three or four directions around the center column, and a plurality of concrete pontoons that connect the center column to each of the side columns, the center column comprising a center column foundation and a center tower that rises from the center column foundation, and the side columns comprising side column foundations and side towers that rise from the side column foundations. and a connecting yard for connecting the center column foundation, the side column foundation, and the pontoon to the center column foundation. The connecting yard includes a fabrication process for fabricating the center column foundation, the side column foundation, and the pontoon in their respective fabrication yards; a first transporting and connecting process for transporting the center column foundation and the pontoon to a connecting yard and connecting one end of the pontoon to the center column foundation; a second transporting and connecting process for transporting the side column foundation to the connecting yard and connecting the other end of the pontoon to the side column foundation; a center tower connecting process for connecting the center tower to the center column foundation; and a side tower connecting process for connecting the side tower to the side column foundation.

[0009] In the present invention, after the center column, side columns, and pontoons that make up the semi-submersible foundation are fabricated, one end of the pontoon is connected to the center column foundation and the other end of the pontoon is connected to the side column foundation, thereby improving connection efficiency and enabling efficient fabrication of floating foundations in a dock. Furthermore, after the center column foundation and side column foundation have been manufactured, a connection method can be used to connect the center tower and side tower to the center column foundation and side column foundation, respectively, which allows the upper structure, such as the center tower and side tower, to be connected to a stable lower structure, thereby improving safety during connection in addition to smoother connections.

[0010] In the present invention, "made of concrete" refers to a center column, side columns, and pontoons made of reinforced concrete (RC), and more specifically, refers to the components of the center column, the components of the side columns, and the components of the pontoons. In addition, in this specification, "concrete" also includes SRC (Steel Reinforced Concrete) structures, which are primarily made of reinforced concrete and contain steel (S: Steel).

[0011] In another embodiment, the manufacturing process may include at least one of the center tower connecting process and the side tower connecting process. That is, the manufacturing process may be configured to include manufacturing a center column (divided body) consisting of a center column foundation and a center tower, and manufacturing a connecting body (divided body) comprising the center column foundation and at least a portion of the center tower. Also, the manufacturing process may be configured to include manufacturing side columns (divided bodies) consisting of a side column foundation and a side tower, and manufacturing a connecting body (divided body) comprising the side column foundation and at least a portion of the side tower.

[0012] In the above-mentioned floating foundation fabrication method, the center tower is made up of one or more center tower elements, the side tower is made up of one or more side tower elements, and the pontoon is made up of one or more pontoon elements. This configuration allows for the fabrication of a variety of segments and the connection of the segments.

[0013] In the method for manufacturing a floating foundation described above, the center column may be manufactured by tensioning the center column foundation and the center tower with a first tendon. In the method for manufacturing a floating foundation described above, the side columns may be manufactured by tensioning the side column foundation and the side tower with a second tendon. In the method for manufacturing a floating foundation described above, the pontoon may be made up of a plurality of pontoon elements, and the pontoon may be manufactured by tensioning each of the pontoon elements with a third tendon. In the method for manufacturing a floating foundation described above, the pontoons may be connected to the center column and the side columns under tension by fourth tendons.

[0014] In this way, by connecting each component under tension using tendons, it is possible to produce a floating foundation with high connection strength and excellent watertightness. It is preferable to use wet joints between each segment that makes up the center tower and side towers, and at the connections between the center column, pontoons, and side columns, and then tension them with tendons.

[0015] In the above-described floating foundation manufacturing method, when the four pontoons are arranged at 90-degree intervals around the center column and the side columns are connected to each pontoon, in the first transport and connection step, the two pontoons facing each other around the center column foundation are tensioned together with the center column foundation by the common third tendon.

[0016] In this configuration, when four pontoons are arranged at 90-degree intervals around the center column and the side columns are connected, the third and fourth tendons are the same tendon, and the two pontoons facing each other around the center column foundation are tensioned together with the center column foundation by the common third tendon, thereby achieving a more efficient connection in the connection yard. [Effects of the Invention]

[0017] According to the method for manufacturing a floating foundation of the present invention, it is possible to efficiently manufacture a floating foundation made of concrete in a dock. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is an overall perspective view showing an example of a floating foundation manufacturing system according to an embodiment. FIG. [Figure 2] 1 is a perspective view showing an example of a floating foundation manufactured by a floating foundation manufacturing method according to an embodiment. FIG. [Figure 3] 1 is a perspective view showing an example of an offshore wind turbine manufactured by a method for manufacturing an offshore wind turbine according to an embodiment. FIG. [Figure 4A] FIG. 2 is a process diagram showing an example of a manufacturing method for the floating foundation according to the first embodiment. [Figure 4B] 4B is a process chart showing an example of a method for manufacturing a floating foundation according to the first embodiment, following FIG. 4A. [Figure 5] 10A to 10C are diagrams showing an example of a method for manufacturing a floating foundation according to the second embodiment and an example of a method for manufacturing a floating foundation according to the third embodiment. [Figure 6] FIG. 1 is a perspective view showing an example of a multi-axle truck. [Figure 7A] 1A and 1B are diagrams showing the arrangement of multi-axle carriages during the first transportation method for floating foundations, where (a) is a plan view showing multiple multi-axle carriages transporting side columns, (b) is a plan view showing multiple multi-axle carriages transporting pontoons, and (c) is a plan view showing multiple multi-axle carriages transporting center columns. [Figure 7B] FIG. 10 is a diagram illustrating an example of a first transportation method in which a floating foundation is transported together with a frame by a plurality of multi-axle carriages. [Figure 8A] Figures showing the arrangement of multi-axle carriages during the second transportation method for floating foundations, where (a), (b), and (c) are plan views of multiple multi-axle carriages transporting side columns, (d), (e), and (f) are plan views of multiple multi-axle carriages transporting pontoons, and (g) is a plan view of multiple multi-axle carriages transporting a center column. [Figure 8B] FIG. 10 is a diagram illustrating an example of a second transportation method in which a floating foundation is transported together with a frame by a plurality of multi-axle carriages. [Figure 9] FIG. 1 is a process diagram showing an example of a launching method for a floating foundation according to an embodiment. [Figure 10] 9, this is a process diagram showing an example of a launching method for a floating foundation according to an embodiment. [Figure 11] 10 , is a process diagram showing an example of a launching method for a floating foundation according to an embodiment. [Figure 12] 11 , this is a process diagram showing an example of the launching method for the floating foundation according to the embodiment. [Figure 13] Following Figure 12, this is a process diagram showing an example of a method for launching a floating foundation according to an embodiment, and also a process diagram showing an example of a method for recovering a platform on which a floating foundation according to an embodiment is mounted. [Figure 14] 13, this is a process diagram showing an example of a method for recovering a platform on which a floating foundation according to an embodiment is mounted. [Figure 15] 14A to 14C are process diagrams showing an example of a method for recovering a platform on which a floating foundation according to an embodiment is mounted. [Figure 16] 15, this is a process diagram showing an example of a method for recovering a platform on which a floating foundation according to an embodiment is mounted. [Figure 17] 16, this is a process diagram showing an example of a method for recovering a platform on which a floating foundation according to an embodiment is mounted. [Figure 18] FIG. 1 is a diagram illustrating a method for manufacturing and towing an offshore wind turbine according to an embodiment. [Figure 19] FIG. 10 is a perspective view showing an example of a floating foundation manufactured by a method for manufacturing a floating foundation according to a fourth embodiment. [Figure 20] FIG. 10 is a diagram showing an example of a method for manufacturing a floating foundation according to the fifth embodiment. [Figure 21] FIG. 10 is a process diagram showing an example of a manufacturing method for a floating foundation according to the sixth embodiment. [Figure 22]21, this is a process diagram showing an example of a method for manufacturing a floating foundation according to another embodiment. [Figure 23] FIG. 10 is a diagram showing another embodiment of the conveying means, which has a traveling body. [Figure 24] FIG. 10 is a diagram showing an example of another embodiment of the conveying means, which is an air caster. DETAILED DESCRIPTION OF THE INVENTION

[0019] Below, we will explain the floating foundation manufacturing method and floating foundation manufacturing system, the offshore wind turbine manufacturing method, the floating foundation launching method, the mounting frame recovery method on which the floating foundation is mounted, and the offshore wind turbine manufacturing and towing method according to the embodiments, with reference to the attached drawings. In this specification and drawings, substantially the same components may be denoted by the same reference numerals to avoid redundant explanation.

[0020] [Manufacturing system and method for a floating foundation, and a manufacturing method for an offshore wind turbine according to an embodiment] First, an example of a floating foundation manufacturing method and a floating foundation manufacturing system, and an offshore wind turbine manufacturing method according to an embodiment will be described with reference to FIGS. 1 to 8. FIG. 1 is an overall perspective view showing an example of a floating foundation manufacturing system according to an embodiment. FIG. 2 is a perspective view showing an example of a floating foundation manufactured by a floating foundation manufacturing method according to an embodiment. FIG. 3 is a perspective view showing an example of an offshore wind turbine manufactured by a method for manufacturing an offshore wind turbine according to an embodiment. Furthermore, FIGS. 4A and 4B are process diagrams showing an example of a floating foundation manufacturing method according to a first embodiment. Furthermore, FIG. 5 is a diagram showing an example of a floating foundation manufacturing method according to a second embodiment and an example of a floating foundation manufacturing method according to a third embodiment.

[0021] In addition, in each figure, the illustration of the steel bars that form each of the concrete (reinforced concrete) components that make up the floating foundation, and the tension members that form each component (connect multiple elements together) and connect each component together are omitted.

[0022] The manufacturing system 60 shown in FIG. 1 is a system for manufacturing a floating foundation, and is installed in a dock D. The floating foundation to be fabricated in the illustrated example is a semi-submersible foundation 70, but the floating foundation fabricated by the fabrication system 60 may also be other floating foundations such as spar type, purge type, TLP type, etc.

[0023] The production system 60 has a plurality of production yards 10 for producing the various types of divided bodies that make up the semi-submersible foundation 70, transport paths 50 provided between each production yard 10, a multi-axle cart 30 that transports the divided bodies produced in each production yard 10 via the transport paths 50, and a connection yard 20 that connects the divided bodies transported by the multi-axle cart 30 to produce the semi-submersible foundation 70.

[0024] Within dock D, to the side of the quay P of the connecting yard 20, there is deployed the offshore S where the manufactured semi-submersible foundation 70 is towed and installed. A barge 90 is moored at the quay P to carry the manufactured semi-submersible foundation 70 and tow it to the predetermined installation position for installation.

[0025] As shown in Figure 2, the semi-submersible foundation 70 has a concrete center column 70A, three concrete side columns 70B arranged at 120-degree intervals in a plan view in three directions around the center column 70A, and three concrete pontoons 70C connecting the central center column 70A to each side column 70B. The three directions at 120 degree intervals are the longitudinal directions of the pontoon 70C, and are therefore defined as the pontoon axial directions.

[0026] The center column 70A includes a center column base 71 and a center tower 72 that stands up from the center column base 71. The side column 70B includes a side column base 73 and a side tower 74 rising from the side column base 73.

[0027] The center tower 72 is a stack of multiple center tower elements 72a, the side tower 74 is a stack of multiple side tower elements 74a, and the pontoon 70C is a connection of multiple pontoon elements 75a.

[0028] These are fabricated as separate bodies in various ways at a specific fabrication yard 10, and the separate bodies are transported to a connection yard 20 and connected to fabricate a semi-submersible foundation 70. In the embodiment, the semi-submersible foundation 70 to be manufactured is provided with three side columns 70B, but it may also be provided with four pontoons 70C arranged at 90-degree intervals in a plan view around a center column 70A (not shown), with a side column 70B connected to each pontoon 70C.

[0029] As shown in Fig. 2, each divided body is placed on its own platform 40. Each platform 40 has a mounting plate 41, a plurality of legs 42 protruding below the mounting plate 41, and an access space 43 below the mounting plate 41 into which the multi-axle carriage 30 enters.

[0030] "A stand specific to each divided body" means that the number of stands 40 corresponds to each divided body at a 1:1 ratio. In addition, if the number of stands 40 is small compared to the number of divided bodies and each divided body is manufactured with a time lag, one stand 40 will be diverted from manufacturing multiple divided bodies to transporting them.

[0031] The center column 70A, the side column 70B, and the pontoon 70C are mounted on respective mounts 40A, 40B, and 40D.

[0032] Returning to FIG. 1, each production yard 10 is provided inside a specific building 18. In the production yard 10, a gantry crane 15 for producing the sections is installed so as to be movable in the X1 direction along a plurality of rails 13.

[0033] In the fabrication yard 10, a frame 40 is installed, and the divided bodies are fabricated on the frame 40.

[0034] There are various types of segments. Referring to Figure 2, the segment includes the center column foundation 71 and the side column foundation 73. The entire center tower 72 may be included in the segment, or each center tower element 72a may be included in the segment, or a portion (in an unfinished state) of the center tower 72 may be included in the segment. This also applies to the side tower 74.

[0035] As for the Pontoon 70C, the entire unit may be included in the division, or a part of it (in an unfinished state) may be included. Here, the pontoon 70C in the illustrated example is a connected body of a plurality of pontoon elements 75a, but the pontoon may also be formed by a single pontoon element.

[0036] The divided bodies produced in the production yard 10 are produced on the platform 40, and then transported together with the platform 40 on a multi-axle trolley 30 to the connection yard 20, where they are connected to other divided bodies on the platform 40.Therefore, the divided bodies can take on a variety of shapes depending on the extent to which they are produced on the platform 40 in the production yard 10.

[0037] For example, when the entire center column 70A is a divided body, the entire center column 70A is manufactured as a divided body on the frame 40 in the manufacturing yard 10. On the other hand, when the center column foundation 71 and the center tower 72 are fabricated on the frame 40 in the fabrication yard 10, the center column foundation 71 and the center tower 72 are fabricated as separate bodies. In addition, each center tower element 72a that makes up the center tower 72 may be manufactured individually, for example, inside the building 18, rather than on the frame 40, and then multiple center tower elements 72a may be placed on the frame 40 and tensioned with multiple tension members to manufacture the center tower 72. Even with this manufacturing method, the center tower 72 is a divided body.

[0038] In any case, the object mounted on the platform 40 and transported together with the platform 40 to the connection yard 20 on the multi-axle trolley 30 is referred to in this specification as a "divided body." In addition to objects that are 100% manufactured on the platform 40 (manufactured from start to finish), "divided bodies" also include objects that are manufactured in a location other than the platform and then connected together on the platform 40.

[0039] In each production yard 10, concrete segments are produced as PCa bodies, and in the connection yard 20, each PCa body segment is tensioned with tendons to produce a PCaPC floating foundation.

[0040] Returning to FIG. 1, in the illustrated example, the center column foundation 71, the side column foundation 73, and the pontoon 70C are fabricated on specific frames 40A, 40B, and 40D in specific fabrication yards 10A, 10B, and 10D, respectively. With regard to the pontoon 70C, multiple pontoon elements 75a are manufactured in a location other than the frame 40D in the production yard 10D, and then the multiple pontoon elements 75a are tensioned with multiple tendons on top of the frame 40D, thereby producing the pontoon 70C.

[0041] The center tower element 72a and the side tower elements 74a are fabricated in a common fabrication yard 10C. The fabricated center tower elements 72a are connected to each other via tendons on a common frame 40, and similarly, the side tower elements 74a are also connected to each other via tendons on the common frame 40 and transported together with the frame 40 to the connection yard 20. As already described, the center tower 72 and the side towers 74 may be manufactured as separate bodies in an unfinished state on the frame 40, transported to the connection yard 20, and then stacked sequentially on the center column foundation 71 and the side column foundation 73.

[0042] Figure 1 also shows a state in which the side column foundation 73 placed on the platform 40B is being transported in the X2 direction via the conveying path 50 to the connecting yard 20 by the multi-axle trolley 30, and a state in which the pontoon 70C placed on the platform 40D is being transported in the X2 direction via the conveying path 50 to the connecting yard 20.

[0043] In the connection yard 20, heavy machinery 55 and the like are used as appropriate to connect the individual sections to each other via tendons on multiple frames 40, thereby producing a semi-submersible foundation 70. Then, as shown in FIG. 3, a tower 82 equipped with a wind turbine 84 is connected to the center column 70A constituting the semi-submersible foundation 70, thereby fabricating an offshore wind turbine 80. In the illustrated example, the tower 82 is connected to the center column 70A, but a single wind turbine tower may be connected to the side column 70B.

[0044] As a method for connecting the tower 82 to the semi-submersible foundation 70, there is a method in which the tower 82 is connected while being lifted by heavy machinery 55 in the connection yard 20, as shown in Figure 1, and there is also a method in which the tower 82 is connected to the semi-submersible foundation 70 installed on the sea (offshore) using a barge equipped with a lifting machine at sea. Another method is to transport the semi-submersible foundation 70 to a barge 90 moored to a quay P, load it on it, and then connect the tower 82 from the quay P using heavy machinery. Furthermore, as will be explained with reference to Figure 18, there is also a method in which, without using a barge, the semi-submersible foundation 70 is floated on the water beside the quay P, and the tower 82 is connected to the quay P using heavy machinery.

[0045] Next, an example of a method for manufacturing the floating foundation according to the first embodiment will be described with reference to FIGS. 4A, 4B, and 2. 4A, 4B, and 2 are process diagrams showing an example of a method for manufacturing a floating foundation according to the first embodiment.

[0046] In the illustrated manufacturing method, a center column foundation 71 and three side column foundations 73 are manufactured as separate bodies on a frame 40 in a specific manufacturing yard 10 (manufacturing process, separate body manufacturing process).

[0047] Next, each divided body is transported to the connecting yard 20 by a multi-axle cart 30 together with its own frame 40, and at the connecting yard 20, the center column foundation 71 and the three side column foundations 73 are positioned together with the frames 40 on which they are placed, and pontoon gaps G are provided between the center column foundation 71 and each side column foundation 73 so that the pontoons 70C can be inserted (transportation and positioning process). The process of transporting the divided bodies together with the frames 40 from each production yard 10 can also be called a divided body transport process.

[0048] That is, the transport and positioning step positions the center column base 71 and each side column base 73 in a posture that does not require movement when connecting other divided bodies thereafter.

[0049] The center column foundation 71, the side column foundation 73, and each pontoon 70C each have an upper deck 76, a lower deck 77, and left and right side walls 78, and are provided with a hollow 79 inside that forms a ballast chamber. A plurality of corresponding sheath pipes (not shown) are provided at corresponding positions on the upper deck 76, lower deck 77, and side walls 78 of the center column foundation 71, side column foundation 73, and each pontoon 70C, and a tensioning material (not shown) is inserted into each sheath pipe and tensioned, thereby connecting the center column foundation 71, side column foundation 73, and each pontoon 70C.

[0050] Next, as shown in FIG. 4B, the pontoons 70C, which have been transported from the production yard 10 together with the frames 40D, are inserted into the pontoon gaps G in the Y1 direction (pontoon insertion step).

[0051] Here, the width t1 of the pontoon gap G shown in Figures 4A and 4B is set to the longitudinal length t2 of the pontoon 70C plus an error length for one or both of manufacturing error and connection error. This allows the pontoon 70C to be reliably inserted into the pontoon gap G between the positioned center column foundation 71 and side column foundation 73. This eliminates the need for construction work that requires moving at least one of the positioned center column foundation 71 and side column foundation 73 because the pontoon 70C cannot be inserted.

[0052] Next, wet joints WJ filled with mortar or the like are constructed between the center column foundation 71 and the side column foundation 73 and the pontoon 70C, and these are tensioned with tensioning materials to connect the center column foundation 71, the side column foundation 73 and the pontoon 70C (pontoon connection process). From the viewpoint of waterproofing, it is desirable to construct wet joints WJ also between adjacent pontoon elements 75a, between center tower elements 72a, and between side tower elements 74a. In addition, between the pontoon elements 75a, between the center tower elements 72a, and between the side tower elements 74a, it is possible that dry joints (adhesive or thin layer mortar applied between elements, no rebar joints) will be used instead of wet joints (WJ).

[0053] Next, the center tower 72 is lifted and connected to the center column foundation 71 using heavy equipment 55 or the like shown in Figure 1 (center tower connection process), and the side towers 74 are lifted and connected to each side column foundation 73 using heavy equipment 55 or the like (side tower connection process), thereby producing the semi-submersible foundation 70 shown in Figure 2. The transport and positioning process, the pontoon insertion process, the pontoon connection process, the center tower connection process, and the side tower connection process can also be collectively referred to as the connection process.

[0054] Although illustration of each tendon is omitted, the center column 70A is fabricated by tensioning the center column base 71 and the center tower 72 with a plurality of first tendons. Furthermore, the side column foundation 73 and the side tower 74 are tensioned by a plurality of second tendons to fabricate each side column 70B. In addition, the pontoon 70C is manufactured in a specific manufacturing yard 10C by tensioning a plurality of pontoon elements 75a with a plurality of third tendons. In the pontoon connecting step, in the connecting yard 20, the pontoon 70C is connected to the center column 70A and the side column 70B under tension using a plurality of fourth tendons. The first to fourth tendons are made of PC steel rods, PC steel wires, etc.

[0055] In the manufacture of a semi-submersible foundation (not shown) in which four pontoons 70C are arranged at 90-degree intervals around a center column 70A and a side column 70B is connected to each pontoon 70C, during the pontoon connection process, it is preferable to use the same third tendon as the third tendon and the fourth tendon, and to tension the two pontoons 70C facing each other around the center column foundation 71 together with the center column foundation 71 using the same third tendon. According to this tensioning method, two pontoons 70C facing each other around the center column foundation 71 are tensioned together with the center column foundation 71 by a common third tendon, thereby achieving a more efficient connection in the connection yard 20.

[0056] According to the method for manufacturing a floating foundation of the first embodiment, the transport and positioning process makes it unnecessary to move the center column foundation 71 and each side column foundation 73 when connecting other segments thereafter, thereby enabling efficient connection between the segments.

[0057] Furthermore, as shown in Figure 4B, by first fabricating the lower structure of the semi-submersible foundation 70 and then connecting the upper structure, such as the center tower 72 and side towers 74, the upper structure can be connected to the stable lower structure efficiently and with high safety.

[0058] Next, an example of a manufacturing method for a floating foundation according to the second and third embodiments will be described with reference to Figure 5 and Figure 2. Note that in the description of the manufacturing method according to the third embodiment, Figure 4A will be referenced.

[0059] In the manufacturing method according to the second embodiment, the center column 70A is manufactured on the mounting base 40A and the side column 70B is manufactured on the mounting base 40B at a specific manufacturing yard 10, and then these divided bodies are transported together with the mounting base 40 to the connection yard 20 for positioning. Then, pontoons 70C are inserted into the respective pontoon gaps G, and the pontoons 70C are connected to the center column 70A and the side columns 70B. The location where the center column 70A (center column foundation 71 and center tower 72) and the side column 70B (side column foundation 73 and side tower 74) are fabricated is not limited to the fabrication yard 10.

[0060] According to this manufacturing method, the number of steps for connecting the segments in the connecting yard 20 is reduced as much as possible, and therefore the efficiency of connecting the segments in the connecting yard 20 is significantly increased.

[0061] In the manufacturing method according to the third embodiment, similar to the method shown in Fig. 4A, a center column foundation 71 and three side column foundations 73 are positioned in a connecting yard 20 together with the frames 40 on which they are placed. Then, as shown in Fig. 5, a center tower 72 and a side tower 74 are connected to each foundation, and the center column 70A and each side column 70B are manufactured in advance, and finally, pontoons 70C are inserted into each pontoon gap G and connected.

[0062] Another method, not shown in the figures, is to first connect the side column foundation 73 or side column 70B to the pontoon 70C in the connection yard 20, and then move the three connecting bodies to connect them to the center column foundation 71 or center column 70A. Furthermore, if the center column foundation 71 and part of the center tower 72 are manufactured as separate bodies, and similarly the side column foundation 73 and part of the side tower 74 are manufactured as separate bodies and transported to the connection yard 20, the pontoon 70C will be connected to these, and the remaining center tower element 72a of the center tower 72 and the remaining side tower element 74a of the side tower 74 will also be connected.

[0063] The method for manufacturing an offshore wind turbine according to the embodiment is a method for connecting a tower 82 to a semi-submersible foundation 70 manufactured by the floating foundation manufacturing method according to the first to third embodiments or the floating foundation manufacturing method according to the other embodiments described above, while lifting the tower 82 using heavy machinery 55 in the connection yard 20, as already explained. Alternatively, the semi-submersible foundation 70 may be towed out to sea (offshore) and installed there, and then the tower 82 may be connected to it using a barge equipped with a lifting machine at sea. Furthermore, there is a method in which the semi-submersible foundation 70 is loaded onto a barge 90 moored to the quay P, and then the tower 82 is connected from the quay P using heavy machinery. Alternatively, as will be explained with reference to Figure 18, there is a method in which, without using a barge, a semi-submersible foundation 70 is floated on the water beside the quay P, and the tower 82 is connected to the quay P using heavy machinery.

[0064] Next, an example of a transport means and an example of a method for transporting a manufactured floating foundation in the connection step of the manufacturing method of a floating foundation according to the embodiment will be described with reference to FIGS. 6 to 8. Fig. 6 is a perspective view showing an example of a multi-axle bogie. Fig. 7A is a diagram showing the arrangement of multi-axle bogies during a first transportation method for a floating foundation, where (a) is a plan view of multiple multi-axle bogies transporting side columns, (b) is a plan view of multiple multi-axle bogies transporting pontoons, and (c) is a plan view of multiple multi-axle bogies transporting a center column. Fig. 8A is a diagram showing the arrangement of multi-axle bogies during a second transportation method for a floating foundation, where (a), (b), and (c) are plan views of multiple multi-axle bogies transporting side columns, (d), (e), and (f) are plan views of multiple multi-axle bogies transporting pontoons, and (g) is a plan view of multiple multi-axle bogies transporting a center column. Figs. 7B and 8B are diagrams illustrating an example of a first transportation method and a second transportation method, respectively, for transporting a floating foundation together with a platform using multiple multi-axle bogies.

[0065] The transport means shown in the figure is a multi-axle vehicle 30, which is an example of a self-propelled vehicle equipped with a lifting mechanism that lifts the platform 40 and lifts it off the ground. The multi-axle bogie 30 has a plurality of axles 33 attached to a long car body 31 in the axial direction (L direction), and each axle 33 is provided with a plurality of pairs of left and right wheels 35 spaced apart in the axial direction of the car body. All of the wheels 35 are attached to the corresponding axles 33 so as to be rotatable in the Y3 direction, and a loading platform 32 on the car body 31 is attached so as to be able to be raised and lowered by a lifting mechanism (not shown).

[0066] The multi-axle trolley 30 enters the entry space 43 of each platform 40 shown in Figure 2, etc., with the platform 32 lowered as in the illustrated example, and when transporting the platform 40 together with the divided body, the platform 32 can be raised by the lifting mechanism to allow the platform 40 to be lifted off the ground.

[0067] Although not shown in the drawings, the transport means may be such that the platform 40 is provided with wheels driven by an actuator, and these driven wheels may serve as the transport means. Alternatively, the platform 40 may be equipped with wheels, and the transport means may be a towable cart or a pushable cart. Furthermore, the transport means may be a mobile lifting machine such as a crane.

[0068] The first transportation method for the semi-submersible foundation 70 shown in Figure 7 is to arrange each multi-axle bogie 30 so that the body axis direction (L direction) of each multi-axle bogie 30 is parallel to or perpendicular to at least one of the three pontoon axis directions during the connection process in the connection yard 20, and to connect each divided body to produce the semi-submersible foundation 70. The axial direction of the car body of each multi-axle bogie 30 may not be strictly in these directions, but may be in a direction that is shifted by a few degrees.

[0069] Next, the semi-submersible foundation 70 is loaded out along with the multiple mounting platforms 40 onto the multiple multi-axle trolleys 30 and transported to the barge 90 moored at the quay P. By controlling all of the wheels 35 of all of the multi-axle trolleys 30 to move in the same direction or approximately the same direction, all of the multi-axle trolleys 30 can be moved in the Y5 direction, which is the transport direction toward the barge 90. Note that controlling the wheels 35 in approximately the same direction means that there is an angle error of, for example, about ±10 degrees with respect to a reference wheel angle along the Y5 direction, which is the load-out direction.

[0070] According to this transportation method, when the semi-submersible foundation 70 is manufactured by connecting the divided bodies on multiple mounting frames 40 in the connecting yard 20, or when the semi-submersible foundation 70 has been manufactured on multiple mounting frames 40 (both connection processes), by controlling all of the wheels 35 of all of the multi-axle bogies 30 to move in the same direction or approximately the same direction, the body axial direction (L direction) of each multi-axle bogie 30 can be moved smoothly in the desired load-out direction without having to be fixed, and the semi-submersible foundation 70 including the mounting frames 40 can be transported stably and smoothly and loaded onto the barge 90. Furthermore, there is no need to change the planar shape of the loading platform 32 of the multi-axle trolley 30 depending on the placement location; in other words, a multi-axle trolley 30 equipped with a loading platform 32 of the same planar shape can be used without being restricted by the placement location.

[0071] On the other hand, in the second transportation method for the semi-submersible foundation 70 shown in Figure 8, during the connection process in the connection yard 20, each multi-axle bogie 30 is positioned with the body axis direction (L direction) of each multi-axle bogie 30 facing in the Y5 direction, which is the transportation direction toward the barge 90, and each divided body is connected to produce the semi-submersible foundation 70.

[0072] Next, when the semi-submersible foundation 70 is loaded out together with the multiple mounting platforms 40 on the multiple multi-axle trolleys 30 and transported to the barge 90 moored at the quay P, each multi-axle trolley 30 can be moved in a straight line to move all of the multi-axle trolleys 30 in the Y5 direction, which is the transport direction toward the barge 90.

[0073] According to this transportation method, when the semi-submersible foundation 70 is produced by connecting the divided bodies on multiple mounting frames 40 in the connection yard 20, or when the semi-submersible foundation 70 has been produced on multiple mounting frames 40 (both are connection processes), the wheels 35 can be moved smoothly in the desired load-out direction by moving them in a straight line without controlling the angle of each wheel 35 to be in the same direction, etc., and the semi-submersible foundation 70 including the mounting frames 40 can be transported stably and smoothly and loaded onto the barge 90. In addition, since the axial direction of the body of all multi-axle trolleys 30 is the transport direction toward the barge 90, as shown in the figure, each multi-axle trolley 30 may be required to have a loading platform 32 with a variety of planar shapes depending on its placement position.

[0074] Next, an example of a method for launching a floating foundation according to an embodiment and an example of a method for recovering a platform on which the floating foundation is mounted will be described with reference to FIGS. Figures 9 to 13 are process diagrams showing an example of a method for launching a floating foundation according to an embodiment, and Figures 13 to 17 are process diagrams showing an example of a method for recovering a platform on which a floating foundation according to an embodiment is mounted.

[0075] As shown in Figure 9, the method for launching the floating foundation according to the embodiment involves mooring a barge 90 in the sea S to the side of the quay P of the connecting yard 20 of the dock D, and then, as already explained, fabricating multiple concrete segments, each on its own platform 40, and connecting the multiple segments on the platforms 40 to fabricate the semi-submersible foundation 70.

[0076] Next, as shown in Fig. 10, the semi-submersible foundation 70 together with the multiple mounting frames 40 are transported in the Y7 direction by multiple multi-axle carts 30 and loaded onto a barge 90. When each mounting frame 40 has been transported onto the deck of the barge 90, each mounting frame 40 is fixed to the deck (this completes the transport process).

[0077] Following the transportation process, the tower 82 may be connected to the semi-submersible foundation 70 from the quay P using heavy machinery to manufacture the offshore wind turbine 80, but here the following description will assume that the installation of the tower 82 is performed offshore.

[0078] After each mounting frame 40 is fixed to the barge 90, all of the multi-axle carriages 30 are moved (evacuated) in the Y8 direction to the connecting yard 20 as shown in Figure 11, and then, as shown in Figure 12, the barge 90 loaded with the semi-submersible foundations 70 together with multiple mounting frames 40 is moved (towed) in the Y9 direction toward the offshore offshore wind turbine installation position.

[0079] Next, as shown in FIG. 13, the barge 90 is submerged in the direction Y10, and the semi-submersible foundation 70 is launched into the water. The barge 90 is submerged by injecting water into a ballast room (not shown) of the barge 90. Alternatively, if the barge 90 has support legs equipped with a lifting mechanism (not shown), the barge 90 can be submerged by lowering the support legs (this is the launching process).

[0080] According to the method for launching a floating foundation shown in the figures, the semi-submersible foundation 70 can be efficiently transported to the barge 90, and after being transported to the barge 90, the semi-submersible foundation 70 can be towed to a predetermined position offshore and launched into the water, thereby achieving stable and smooth launching of the semi-submersible foundation 70.

[0081] On the other hand, the method for recovering the platform on which the floating foundation of the embodiment is mounted is to submerge a barge 90 carrying multiple platforms 40 and semi-submersible foundations 70 in the Y10 direction at the installation position of the semi-submersible foundations 70, as shown in Figure 13. Then, after the semi-submersible foundation 70 is floated (raised) on the water surface, the barge 90 is moved in the Y11 direction to a position away from the semi-submersible foundation 70 as shown in FIG.

[0082] If the barge 90 is equipped with a ballast room not shown, the barge 90 can be submerged by injecting water into the ballast room, and the barge 90 can be surfaced by discharging ballast water from the ballast room. Furthermore, if the barge 90 has support legs equipped with a lifting mechanism not shown, the barge 90 can be submerged by lowering the lifting mechanism, and the barge 90 can be surfaced by raising the lifting mechanism.

[0083] Next, as shown in Figure 15, (part of) the barge 90 is raised onto the water in the direction Y12, and as shown in Figure 16, the barge 90 carrying multiple platforms 40 is pulled back to the quay P in the direction Y13 (pulling back process).

[0084] After the pulled-back barge 90 is moored to the quay P, the multiple multi-axle carriages 30 waiting in the connecting yard 20 are moved from the quay P to the barge 90 in the Y14 direction.

[0085] The multiple mounting platforms 40 fixed to the deck of the barge 90 are released, the multiple multi-axle trolleys 30 are allowed to enter the entry spaces 43 of the corresponding mounting platforms 40, the loading platform 32 is raised to lift the mounting platforms 40 and remove them from the ground, and then, as shown in Figure 17, each multi-axle trolley 30 is moved in the direction Y15 from the barge 90 to the quay P, thereby recovering the multiple mounting platforms 40 from the barge 90 to the quay P (this is the recovery process).

[0086] According to the illustrated example of the method for recovering a platform on which a floating foundation is mounted, when recovering multiple platforms 40, the barge 90 that has raised the semi-submersible foundation 70 to the water is towed back to the quay P, and then multiple multi-axle trolleys 30 are moved from the quay P to the barge 90, and the multiple platforms 40 are recovered from the barge 90 to the quay P using the multiple multi-axle trolleys 30, thereby allowing the platforms 40 to be recovered efficiently and reliably.

[0087] Next, an example of a method for manufacturing and towing an offshore wind turbine according to an embodiment will be described with reference to Fig. 18. Fig. 18 is a diagram for explaining a method for manufacturing an offshore wind turbine, among the methods for manufacturing and towing an offshore wind turbine.

[0088] As already explained, the offshore wind turbine manufacturing method shown in the figure differs from the method of connecting the tower 82 (see Figure 3) to the semi-submersible foundation 70 at the connection yard 20, or the method of connecting the tower 82 from the quay P to the semi-submersible foundation 70 mounted on a barge 90 on the water, in that the semi-submersible foundation 70 is floated above the water next to the quay P and the tower 82 is connected to the quay P.

[0089] In Figure 18, the dashed dotted lines indicate the seabed B and the quay wall P, as well as the water depth t5 and draft t6 of the semi-submersible foundation 70 before water is poured into the ballast room 79A equipped in the semi-submersible foundation 70. In contrast, the solid lines indicate the seabed B and the quay wall P, as well as the water depth t7 and draft t8 of the semi-submersible foundation 70 after water has been poured into the ballast room 79A, and the water depths t5 and t7 before and after water pouring are substantially unchanged.

[0090] The semi-submersible foundation 70 is lowered onto the water from the quay P by heavy equipment 56, which is a mobile lifting machine such as a crane, and water is poured into the ballast chamber 79A of the semi-submersible foundation 70 moored to the quay P, thereby adjusting the draft t8 of the semi-submersible foundation 70 to be smaller than the water depth t7 of the quay P, and lowering the level of the semi-submersible foundation 70 below the level before the water was poured in. This level adjustment makes it possible to lower the lifting height of the tower 82 by the heavy equipment 56 as low as possible, thereby improving the connectivity of the tower to the floating foundation (preparation process).

[0091] Next, the tower 82 is lifted and connected to the semi-submersible foundation 70, which has been raised above the water, using heavy machinery 56, thereby completing the offshore wind turbine 80 (see FIG. 3).

[0092] In addition, by adjusting the level of the semi-submersible foundation 70 to lower it, the semi-submersible foundation 70 can also be placed on the seabed B beside the quay P.

[0093] According to this method, the semi-submersible foundation 70 can be stabilized in an immovable position when connecting the tower 82, thereby improving the yield when connecting the tower 82 to the semi-submersible foundation 70.

[0094] In addition, the method of connecting the tower 82 to the semi-submersible foundation 70 may be, in addition to using heavy machinery 56, a method in which the tower 82 is erected using an erection device (not shown) located on the quay P and connected to the semi-submersible foundation 70. Alternatively, a method may be used in which tower 82 is connected to semi-submersible foundation 70 using a self-elevating platform (SEP) on the water (the above is the offshore wind turbine manufacturing process).

[0095] Next, after the offshore wind turbine 80 is fabricated beside the quay P, ballast water is drained from the ballast chamber 79A of the semi-submersible foundation 70 and the draft is returned to the draft for towing. After that, the offshore wind turbine is towed to a predetermined position offshore (towing process).

[0096] During the towing process, ballast water is injected into the ballast chamber 79A as necessary to increase the draft, thereby enabling the semi-submersible foundation 70 to be towed in a stable position.

[0097] According to the method for constructing and towing an offshore wind turbine shown in the figure, water is poured into the ballast chamber 79A of the semi-submersible foundation 70 to make the draft of the semi-submersible foundation 70 smaller than the water depth of the quay P, and adjustments are made to lower the level of the semi-submersible foundation 70, and then the tower 82 is connected to the semi-submersible foundation 70 in a state where it is floating above the water to construct the offshore wind turbine 80, thereby ensuring good connectivity of the tower 82 to the semi-submersible foundation 70. Then, after discharging ballast water from the ballast room 79A and returning the draft to the draft for towing, the offshore wind turbine 80 can be towed safely to the designated position offshore.

[0098] It should be noted that the present invention is not limited to the configurations shown here, and other embodiments may be possible in which other components are combined with the configurations described in the above embodiments. In this regard, the present invention can be modified within the scope of the present invention, and can be appropriately determined depending on the application form.

[0099] FIG. 19 is a perspective view showing an example of a floating foundation manufactured by the method for manufacturing a floating foundation according to the fourth embodiment. In the fourth embodiment of the present invention, as shown in FIG. 19, concrete pouring portions 72b, 74b, and 75b are provided on a center column 70A, a side column 70B, and a pontoon 70C. In the embodiment shown in FIG. 19, the entire center tower 72, the entire side tower 74, and the entire pontoon 70C are formed by concrete pouring sections 72b, 74b, and 75b, respectively.

[0100] In this configuration, concrete is poured in the production yard to form the center column foundation 71 and the side column foundation 73, which form part of the concrete pouring sections 72b, 74b, and the pontoon 70C, which consists of the concrete pouring section 75b, and then the center column foundation 71, the side column foundation 73, and the pontoon 70C are transported to the connecting yard 20. Thereafter, in the connection yard 20, the center tower 72, which constitutes the remaining part of the concrete pouring section 72b, is connected to the center column foundation 71, and the side tower 74, which constitutes the remaining part of the concrete pouring section 74b, is connected to the side column foundation 73. In addition, the pontoon 70C, which consists of the concrete pouring section 75b, is connected to the center column foundation 71 and the side column foundation 73.

[0101] In the fourth embodiment described above, the foundation has concrete pouring sections 72b, 74b, 75b formed by pouring concrete in the production yard and the connection yard 20. This makes it possible to reduce the need for lifting equipment such as cranes compared to when the entire division body or the elements that make up the division body are transported from outside the production yard or the connection yard, thereby reducing the manufacturing cost of the semi-submersible foundation 70.

[0102] The center tower 72 consisting of the concrete pouring section 72b may be formed by pouring concrete on the platform 40 of the work yard or on the platform 40 of the connection yard 20. In addition, the side tower 74 consisting of the concrete pouring section 74b may be formed by pouring concrete on the platform 40 of the work yard or on the platform 40 of the connection yard 20. In addition, the pontoon 70C consisting of the concrete pouring portion 75b may be formed by pouring concrete on the platform 40 of the work yard or on the platform 40 of the connection yard 20. In this way, even if the site area of ​​the work yard or connection yard 20 is small, the concrete semi-submersible foundation 70 can be manufactured more efficiently.

[0103] Although the method for forming the concrete pouring sections is not limited, if the concrete pouring sections 72b, 74b, 75b, such as the center tower 72, side tower 74, and pontoon 70C, have uniform cross sections or irregular cross sections, and are formed using the slip form method in the production yard or on the platform 40, the concrete pouring sections 72b, 74b, 75b can be produced accurately in a short period of time. The formwork for the slip form method may be installed on the fabrication yard, or may be installed on the pedestal 40 (or the center column foundation 71, side column foundations 73). In other words, after constructing the entire center tower 72 (i.e., a single center tower element) using the formwork for the slip form method installed on the fabrication yard, the center tower 72 may be installed on the center column foundation 71 mounted on the pedestal 40, or the formwork for the slip form method may be installed on the center column foundation 71 mounted on the pedestal 40, and the center tower 72 may be constructed directly on the center column foundation 71. Similarly, the entire side tower 74 (i.e., a single side tower element) may be constructed using a slipform formwork set up in a production yard, and then the side tower 74 may be installed on the side column foundation 73 mounted on the frame 40, or a slipform formwork may be set up on the side column foundation 73 mounted on the frame 40, and the side tower 74 may be constructed directly on the side column foundation 73.

[0104] In the above-described configuration, a concrete pouring portion 75b may be provided in a portion of the pontoon 70C. In this configuration, the pontoon 70C is manufactured by placing the pontoon element 75a in the connection yard 20 and then pouring concrete to form the concrete pouring portion 75b.

[0105] FIG. 20 is a diagram showing an example of a method for manufacturing a floating foundation according to the fifth embodiment. In the fifth embodiment of the present invention, as shown in FIG. 20 , in the fabrication process, a segment including a center column foundation 71 and at least a portion (lower portion) of a center tower 72 is fabricated, and a segment including a side column foundation 73 and at least a portion (lower portion) of a side tower 74 is fabricated, and then these segments are transported to the connecting yard 20. These segments constitute concrete pouring sections and are formed by pouring concrete in the fabrication yard. In the configuration of FIG. 20 , the remaining portions of the center tower 72 and the side towers 74 are fabricated in the connecting yard 20, for example, by pouring concrete. Note that, after installing a slip-form formwork for constructing the center tower 72 on the center column foundation 71 in the fabrication yard and starting concrete pouring in the portion that will become the lower portion of the center tower 72, the segment may be transported to the connecting yard 20 without removing the formwork (i.e., while the concrete is curing), and construction of the remaining portion of the center tower 72 may continue in the connecting yard 20. The same applies to the side tower 74.

[0106] Fig. 21 is a process diagram showing an example of a method for manufacturing a floating foundation according to the sixth embodiment. Fig. 22 is a process diagram showing an example of a method for manufacturing a floating foundation according to another embodiment, following Fig. 21. In a sixth embodiment of the present invention, as shown in FIG. 21, a center column foundation 71, a side column foundation 73, and a pontoon 70C are manufactured in their respective manufacturing yards (manufacturing process), and then the center column foundation 71 and the pontoon 70C are transported to a connection yard 20, and one end of the pontoon 70C is connected to the center column foundation 71 (first transportation and connection process). Thereafter, as shown in FIG. 22, the side column foundation 73 is transported to the connection yard 20, and the other end of the pontoon 70C is connected to the side column foundation 73 (second transport and connection step). Furthermore, as shown in FIG. 2, the center tower 72 is connected to the center column foundation 71 (center tower connecting step), and the side tower 74 is connected to the side column foundation 73 (side tower connecting step). By doing so, the connection efficiency can be improved, and therefore the semi-submersible foundation 70 can be efficiently manufactured in the dock.

[0107] In the present invention, in the manufacturing process, a center column 70A consisting of a center column foundation 71 and a center tower 72 may be manufactured, and a side column 70B consisting of a side column foundation 73 and a side tower 74 may be manufactured, and then the center column 70A and the side column 70B may be transported to the connecting yard 20.

[0108] In the present invention, the manufacturing location of the center column 70A by tensioning the center column foundation 71 and center tower 72 shown in Figure 2 with a first tendon, the manufacturing of the side column 70B by tensioning the side column foundation 73 and side tower 74 with a second tendon, and the manufacturing of the pontoon 70C by tensioning each pontoon element 75a with a third tendon is not limited, and may be performed, for example, in a manufacturing yard or on the platform 40 of the connection yard 20. Furthermore, the segments may be temporarily joined together with bolts or the like before being connected by the tendons.

[0109] In the present invention, adjacent divided bodies may be connected to each other by forming a gap between them and pouring concrete into the gap or filling the gap with an adhesive.

[0110] In the above embodiment, the platform 40 is lifted and transported by the multi-axle cart 30 shown in FIG. 6, but the configuration of the transport means is not limited thereto. FIG. 23 is a diagram showing another embodiment of the conveying means, which has a traveling body. For example, as shown in Fig. 23, it is also possible to use a transport means 110 that is placed under the platform 40 and has a running body 112 that moves on rails 111 laid in the connection yard 20. The running body 112 of the transport means 110 is provided with a lifting jack 113 that is extendable and retractable in the vertical direction, and a running jack 114 connected to the rails 111.

[0111] In the transport means 110, the platform 40 is placed on the upper end of the lifting jack 113 and extended to lift the platform 40 off the ground, and the traveling jack 114 is extended and retracted to move the traveling body 112 along the rails 111. With this configuration, the divided body including the platform 40 can be transported stably.

[0112] FIG. 24 is a diagram showing an example of another embodiment of the conveying means, which is an air caster. 24, an air caster 120 can be used as the transport means, which has a plate-like member 121 placed under the stand 40 and a plurality of bags 122 placed below the plate-like member 121, and is configured to inflate the bags 122 and cause air to flow over the outer surfaces of the bags 122. The air caster 120 uses air pressure to lift the object to be transported.

[0113] In the air caster 120, with each bag body 122 in a deflated state, the plate-like member 121 is placed under the base 40, and each bag body 122 is inflated, thereby lifting the plate-like member 121 and the base 40 and lifting the base 40 off the ground. Furthermore, air is circulated over the outer surface of the inflated bag body 122, forming a thin air film between the bag body 122 and the ground, thereby reducing the friction between the bag body 122 and the ground. This allows the divided body, including the base 40, to be moved smoothly with little force. [Explanation of symbols]

[0114] 10 Fabrication Yards 10A Production Yard 10C Production Yard 10D Production Yard 13 Rail 15 Gantry crane 18 Building 20 connecting yards 30 Multi-axle trolley 31 Body 32 Cargo bed 33 axles 35 wheels 40 Mounting stand 40A stand 40B Mount 40D Mounting Stand 41 Mounting Plate 42 legs 43 Approach space 50 Conveyor path 55 Heavy Machinery 56 Heavy Machinery 60 Crafting System 70 Semi-submersible foundation 70A Center Column 70B Side Column 70C Pontoon 71 Center Column Foundation 72 Center Tower 72a Center Tower Element 73 Side column foundation 74 Side Tower 74a Side Tower Element 75a Pontoon Element 76 Upper deck version 77 Lower floor version 78 Side wall 79 Hollow 79A Ballast Room 80 Offshore Wind Turbines 82 Tower 84 Windmill 90 barges 110 Means of transport 111 Rail 112 Running body 113 Lifting Jack 114 Traveling jack 120 Air Caster 121 Plate-shaped members 122 Bag body B Undersea D Dock G. Pontoon clearance P quay S Maritime WJ Wet Joint

Claims

1. A method for fabricating a floating foundation that supports a tower of an offshore wind turbine, comprising the steps of: The floating foundation is a semi-submersible foundation, A concrete center column and a plurality of concrete side columns arranged at intervals in three or four directions around the center column; a plurality of concrete pontoons connecting the center column and each of the side columns; The center column is Center column foundation and a center tower rising from the center column foundation, The side column is Side column foundations and a side tower rising from the side column foundation, a manufacturing process of manufacturing the center column foundation, the side column foundation, and the pontoon in each manufacturing yard; a first transportation and connection step of transporting the center column foundation and the pontoon to a connection yard and connecting one end of the pontoon to the center column foundation; a second transportation and connection step of transporting the side column foundation to the connection yard and connecting the other end of the pontoon to the side column foundation; a center tower connecting step of connecting the center tower to the center column foundation; a side tower connecting step of connecting the side tower to the side column foundation.

2. 2. The method for manufacturing a floating foundation according to claim 1, wherein the manufacturing process includes at least one of the center tower connecting process and the side tower connecting process.

3. The center tower is composed of a single or multiple center tower elements, The side tower may be composed of a single or multiple side tower elements, The method for manufacturing a floating foundation according to claim 1, wherein the pontoon comprises a single or multiple pontoon elements.

4. 2. The method for manufacturing a floating foundation according to claim 1, wherein the center column is manufactured by tensioning the center column foundation and the center tower with a first tendon.

5. 2. The method for manufacturing a floating foundation according to claim 1, wherein the side column is manufactured by tensioning the side column foundation and the side tower with a second tendon.

6. The pontoon is made up of a plurality of pontoon elements, 2. The method for manufacturing a floating foundation according to claim 1, wherein the pontoons are manufactured by tensioning each of the pontoon elements with a third tendon.

7. 2. The method for manufacturing a floating foundation according to claim 1, wherein the pontoons are connected to the center column and the side columns under tension by fourth tendons.

8. In the case where four of the pontoons are arranged at 90 degree intervals around the center column and the side columns are connected to each of the pontoons, 7. The method for manufacturing a floating foundation according to claim 6, wherein in the first transporting and connecting step, the two pontoons facing each other with respect to the center column foundation are tensioned together with the center column foundation by the common third tendon.

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