Method for constructing a floating foundation

Abstract

To provide a floating type foundation fabrication method capable of stably and smoothly transferring a heavy semi-submersible type concrete foundation to a trestle.SOLUTION: A fabrication method for a floating type foundation which is a semi-submersible type foundation 70 supporting a tower of an offshore windmill comprises at least: a segment body fabrication process to fabricate a center column foundation 71, a side column foundation 73 and a pontoon 70C as segment bodies on trestles 40 in respective fabrication yards; a segment body transfer process to transfer the trestles 40 with respective segment bodies mounted thereon to a connection yard using multi-axis trolleys; and a connecting process to fabricate the floating type foundation 70 by connecting segment bodies to each other. Each multi-axis trolley is arranged with an axis direction thereof parallel to or normal to at least one of three or four pontoon axial directions. All wheels on one trolley are controlled to be steered in an identical or almost identical direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a floating foundation.

Background Art

[0002] For the purpose of reducing greenhouse gas emissions, the demand for renewable energy is increasing. Renewable energy includes, for example, solar power generation, wind power generation, hydroelectric power generation, geothermal power generation, biomass, etc. Wind power generation facilities may have an impact on the living environment due to noise and vibration from wind turbines, and it is necessary to fully consider the impact on living spaces, etc., so they are often installed in mountainous areas away from residential areas. However, it is difficult to secure land for installing large wind turbines in mountainous areas, and it is also difficult to secure transportation routes to wind power generation facilities and install transmission lines, etc. Therefore, technological development for installing offshore wind turbines, which are components of wind power generation facilities, on the sea (including water and lakes) is underway. When constructing an offshore wind turbine on the sea, a floating foundation may be adopted as its foundation. There are semi-submersible types, spar types, barge types, TLP (Tension Leg Platform) types, etc. among these floating foundations. Among these, a semi-submersible type foundation (semi-submersible floating foundation) has a center column that supports the tower (pillar) of the wind turbine, a plurality (3 or 4) of side columns arranged at intervals around the center column, and pontoons that connect the center column and the side columns. Since it can exhibit excellent stability against waves and sea winds, it is a foundation with relatively many achievements.

[0003] Since the conventional floating foundation is generally made of steel, the soaring manufacturing cost is one of the problems, and this problem becomes more prominent as the scale of the floating foundation increases. Therefore, while it is possible to reduce manufacturing costs by fabricating a semi-submersible concrete foundation in a dock and towing it out to sea for installation, currently, an efficient method for fabricating a semi-submersible concrete foundation in a dock has not been established. Thus, a method for fabricating a floating foundation that can achieve efficient fabrication is desired. Furthermore, there is a need for technology to stably and smoothly transport heavy concrete semi-submersible foundations, manufactured in a dock, during loadout, for example, to a barge moored at a quay.

[0004] Here, Patent Document 1 proposes a tower assembly method in which multiple tower members, formed by dividing the tower of an offshore wind turbine in the height direction, are assembled on a jack-equipped frame constructed on a base installed on the ground. On the other hand, Patent Document 2 proposes an offshore wind turbine installation method in which the tower of the offshore wind turbine is divided in the height direction and multiple tower members are assembled and installed offshore. This installation method includes a caisson installation step of installing a caisson, which will serve as the foundation of the offshore wind turbine, at the installation location of the offshore wind turbine; an assembly step of assembling multiple tower members using the caisson; and a blade installation step of attaching blades to the nacelle attached to the uppermost tower member using the caisson. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2021-80852 [Patent Document 2] Japanese Patent Publication No. 2021-76043 [Overview of the project] [Problems that the invention aims to solve]

[0006] Although Patent Documents 1 and 2 describe efficient methods for assembling towers, as mentioned above, they do not describe techniques for efficiently manufacturing semi-submersible floating foundations made of concrete in a dock, nor do they describe techniques for stably and smoothly transporting heavy semi-submersible concrete foundations to barges during loadout.

[0007] The present invention aims to provide a method for manufacturing floating foundations that enables the efficient production of semi-submersible concrete foundations in docks and allows for the stable and smooth transport of heavy semi-submersible concrete foundations to barges. [Means for solving the problem]

[0008] To achieve the above objective, one aspect of the method for manufacturing a floating foundation according to the present invention is: A method for manufacturing a floating foundation that supports the tower of an offshore wind turbine, comprising a concrete center column, a plurality of concrete side columns arranged at intervals in three or four directions around the center column, and a plurality of concrete pontoons connecting the center column and each side column, wherein the center column comprises a center column foundation and a center tower rising from the center column foundation, and the side columns comprise side column foundations and side towers rising from the side column foundations, and is a semi-submersible type foundation for supporting the tower of an offshore wind turbine. At a minimum, the process includes manufacturing the center column foundation, the side column foundation, and the pontoon as separate parts, and manufacturing each part on a stand in its respective manufacturing yard. A multi-axle trolley, unique to each of the aforementioned divided bodies, is placed beneath each of the aforementioned frames on which each divided body is mounted. The loading platform of the multi-axle trolley is raised to lift the frame off the ground, and the divided body is transported to the connecting yard by the multi-axle trolley, in a divided body transport process. The connection yard comprises a connection process in which each of the divided sections is mounted on the frame and connected to each other to manufacture the floating foundation, The aforementioned multi-axle bogie has multiple pairs of wheels mounted in the axial direction of the body on a long body, all of which are rotatably mounted on the body, and the loading platform on top of the body is mounted to be able to be raised and lowered by a lifting mechanism. The connection step is characterized by arranging each multi-axle bogie so that the body axis direction of each multi-axle bogie is parallel to or perpendicular to at least one of the three or four pontoon axis directions, and controlling all the wheels of all the multi-axle bogies in the same direction or substantially the same direction.

[0009] According to this embodiment, after manufacturing multiple concrete segments that form a floating foundation on frames located in their respective manufacturing yards, a multi-axle trolley is placed (inserted) under each frame on which the segments are mounted, the platform of the multi-axle trolley is raised to lift the frames off the ground, the segments are transported together with the frames by the multi-axle trolley to the connecting yard, and the segments are connected on multiple frames in the connecting yard to manufacture the floating foundation, thereby enabling the efficient manufacture of concrete floating foundations in a dock. Furthermore, when connecting the divided sections in the connecting yard, by arranging each multi-axle bogie so that its body axis direction is parallel to or perpendicular to at least one of the three or four pontoon axis directions, and then controlling all the wheels of all the multi-axle bogies to move in the same direction or substantially the same direction, it is possible to move each multi-axle bogie smoothly in the desired loadout direction without restricting its body axis direction to a certain direction, and the floating foundation including the frame can be transported and loaded onto the barge stably and smoothly.

[0010] Here, "concrete divisions" refers to center columns, side columns, and pontoons made of reinforced concrete (RC), and more specifically, to the components of the center columns, side columns, and pontoons. Furthermore, in this specification, SRC (Steel Reinforced Concrete) structures, which primarily use RC structures but also include steel (S), are also included under the term "concrete." By manufacturing these segmented units on their respective frames, the transportability of the manufactured segments along with the frames to the connecting yard is improved. Furthermore, at the connecting yard, the segments are connected to each other while each segment is mounted on its own frame, resulting in good connectivity within the yard. The combination of good transportability from each manufacturing yard to the connecting yard and good connectivity within the connecting yard leads to the efficient manufacturing of floating foundations.

[0011] Furthermore, "at least the center column foundation is manufactured at the manufacturing yard" includes the manufacturing of the center column foundation at the manufacturing yard, the manufacturing of the center column consisting of the center column foundation and the center tower, and the manufacturing of a part of the connecting structure between the center column foundation and the center tower. Furthermore, fabrication on the frame includes not only cases where the entire structure is fabricated on the frame, but also cases where the center column foundation and center tower, fabricated elsewhere, are mounted on the frame, and the center column is formed on the frame. In any case, when transporting to the connection yard, the center column foundation and center column to be transported will be mounted on the frame and transported together with the frame using the transport means. The above explanation regarding the center column foundation is also applicable to the requirements of "fabricating at least the side column foundations in the fabrication yard" and "fabricating at least the pontoons."

[0012] Furthermore, "parallel to or perpendicular to at least one of the three or four pontoon axis directions" means, for example, in the case of three directions, three pontoons extend from the central column at 120-degree intervals in a plan view, and the axis direction of each multi-axle bogie is oriented in one of the three directions of 0, 120, and 240 degrees, or in a direction perpendicular to these. Similarly, in the case of four directions, four pontoons extend at 90-degree intervals in a plan view, and the axis direction of each multi-axle bogie is oriented in one of the four directions of 0, 90, 180, and 270 degrees, or in a direction perpendicular to these. Furthermore, the phrase "parallel to or perpendicular to at least one of the directions" includes not only the vehicle's axis direction being strictly aligned with these directions, but also being offset by a few degrees. Furthermore, "approximately the same direction" in wheel angle control means that there is an angular error of, for example, ±10 degrees relative to the reference wheel angle along the loadout direction.

[0013] At the connecting yard, the center column foundation, pontoons, and side column foundations are tensioned with tensioning materials such as PC (Prestressed Concrete) steel bars and PC steel wires to create a floating foundation. In other words, at each fabrication yard, the concrete center column foundation and side column foundations are fabricated as PCa (Precast Concrete) bodies, and at the connecting yard, each PCa body is tensioned with tensioning materials to create a floating foundation made of PCaPC (Precast Prestressed Concrete). Furthermore, if the center column foundation and center tower are connected at the fabrication yard and the center column is fabricated on a frame, the PCaPC center column will be fabricated at the fabrication yard, and this also applies to the side columns and pontoons.

[0014] Furthermore, other embodiments of the method for manufacturing a floating foundation according to the present invention include: A method for manufacturing a floating foundation that supports the tower of an offshore wind turbine, comprising a concrete center column, a plurality of concrete side columns arranged at intervals in three or four directions around the center column, and a plurality of concrete pontoons connecting the center column and each side column, wherein the center column comprises a center column foundation and a center tower rising from the center column foundation, and the side columns comprise side column foundations and side towers rising from the side column foundations, and is a semi-submersible type foundation for supporting the tower of an offshore wind turbine. At a minimum, the process includes manufacturing the center column foundation, the side column foundation, and the pontoon as separate parts, and manufacturing each part on a stand in its respective manufacturing yard. A multi-axle trolley, unique to each of the aforementioned divided bodies, is placed beneath each of the aforementioned frames on which each divided body is mounted. The loading platform of the multi-axle trolley is raised to lift the frame off the ground, and the divided body is transported to the connecting yard by the multi-axle trolley, in a divided body transport process. The connection yard comprises a connection process in which each of the divided sections is mounted on the frame and connected to each other to manufacture the floating foundation, The aforementioned multi-axle bogie has multiple pairs of wheels mounted in the axial direction of the body on a long body, all of which are rotatably mounted on the body, and the loading platform on top of the body is mounted to be able to be raised and lowered by a lifting mechanism. The connection process is characterized by setting the vehicle axis direction of all the multi-axle bogies to the same direction or substantially the same direction.

[0015] According to this embodiment, when manufacturing a floating foundation by connecting divided sections on multiple frames in a connecting yard, or when a floating foundation has been manufactured on multiple frames (both are connection processes), by setting the axial direction of all multi-axle bogies to be the same or approximately the same direction, it becomes unnecessary to control the angle of each wheel in the same direction, etc., and by moving each multi-axle bogie straight in the loadout direction, the floating foundation including the frames can be transported stably and smoothly and loaded onto a barge. Here, the "substantially the same direction" in the vehicle body axis direction of the multi-axis carriage includes a direction that is deviated by about several degrees with respect to the load-out direction.

[0016] Also, in another aspect of the method for manufacturing a floating foundation according to the present invention, the connecting step includes a center tower connecting step of connecting the center tower to the center column foundation, and a side tower connecting step of connecting the side tower to the side column foundation, and is characterized in that.

[0017] According to this aspect, the center tower connecting step and the side tower connecting step are included in the connecting step. In other words, in the split body manufacturing step, the center column foundation, the side column foundation, and the pontoon are manufactured on the gantry of each manufacturing yard and transported to the connecting yard. Therefore, the weight during transportation from each manufacturing yard to the connecting yard is minimized, and the transportability is improved.

[0018] Also, in another aspect of the method for manufacturing a floating foundation according to the present invention, the split body manufacturing step includes a center tower connecting step of connecting the center tower to the center column foundation, and a side tower connecting step of connecting the side tower to the side column foundation, and is characterized in that.

[0019] According to this aspect, the center tower connecting step and the side tower connecting step are included in the split body manufacturing step. In other words, in the connecting step, the center column and the side column that have already been manufactured on the gantry are transported to the connecting yard and connected. Therefore, the connectivity in the connecting yard is improved.

Effects of the Invention

[0020] According to the present invention's method for manufacturing a floating foundation, it is possible to efficiently manufacture a semi-submersible type floating foundation made of concrete in a dock, and to transport the heavy semi-submersible type foundation made of concrete to a barge in a stable and smooth manner. [Brief explanation of the drawing]

[0021] [Figure 1] This is an overall perspective view of an example of a floating foundation manufacturing system according to an embodiment. [Figure 2] This is a perspective view of an example of a floating foundation manufactured by the floating foundation manufacturing method according to the embodiment. [Figure 3] This is a perspective view of an example of an offshore wind turbine manufactured by the offshore wind turbine manufacturing method according to the embodiment. [Figure 4A] This is a process diagram of an example of a method for manufacturing a floating foundation according to the first embodiment. [Figure 4B] Following Figure 4A, this is a process diagram illustrating an example of a manufacturing method for a floating foundation according to the first embodiment. [Figure 5] This figure shows both 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] This is a perspective view of an example of a multi-axle bogie. [Figure 7A] This figure shows the arrangement of multi-axle trolleys in the first method of transporting a floating foundation, where (a) is a plan view of multiple multi-axle trolleys transporting side columns, (b) is a plan view of multiple multi-axle trolleys transporting pontoons, and (c) is a plan view of multiple multi-axle trolleys transporting center columns. [Figure 7B] This diagram illustrates an example of a first transport method in which a floating foundation is transported together with a support structure using multiple multi-axle trolleys. [Figure 8A] This figure shows the arrangement of multi-axle trolleys in the second method of transporting a floating foundation, where (a), (b), and (c) are plan views of multiple multi-axle trolleys transporting side columns, (d), (e), and (f) are plan views of multiple multi-axle trolleys transporting pontoons, and (g) is a plan view of multiple multi-axle trolleys transporting a center column. [Figure 8B] This diagram illustrates an example of a second transport method in which a floating foundation is transported together with a support structure using multiple multi-axle trolleys. [Figure 9] This is a process diagram illustrating an example of a method for launching a floating foundation according to an embodiment. [Figure 10] Following Figure 9 is a process diagram illustrating an example of a method for launching a floating foundation according to this embodiment. [Figure 11] Following Figure 10 is a process diagram illustrating an example of a method for launching a floating foundation according to the embodiment. [Figure 12] Following Figure 11, the next diagram shows an example of a launching method for a floating foundation according to this embodiment. [Figure 13] Following Figure 12 is a process diagram of an example of a method for launching a floating foundation according to the embodiment, and a process diagram of an example of a method for recovering a frame on which the floating foundation according to the embodiment is mounted. [Figure 14] Following Figure 13, this is a process diagram illustrating an example of a method for recovering a frame on which a floating foundation according to the embodiment is mounted. [Figure 15] Following Figure 14, this is a process diagram illustrating an example of a method for recovering a frame on which a floating foundation according to the embodiment is mounted. [Figure 16] Following Figure 15, this is a process diagram illustrating an example of a method for recovering a frame on which a floating foundation according to the embodiment is mounted. [Figure 17] Following Figure 16, this is a process diagram illustrating an example of a method for recovering a frame on which a floating foundation according to the embodiment is mounted. [Figure 18] This diagram illustrates the manufacturing and towing method of an offshore wind turbine according to an embodiment. [Modes for carrying out the invention]

[0022] The following describes, with reference to the attached drawings, the manufacturing method and system for the floating foundation according to the embodiment, the manufacturing method for the offshore wind turbine, the launching method for the floating foundation, the recovery method for the frame on which the floating foundation is mounted, and the manufacturing and towing method for the offshore wind turbine. In this specification and in the drawings, substantially identical components are denoted by the same reference numerals to avoid redundant explanations.

[0023] [Manufacturing system and method for a floating foundation according to an embodiment, and manufacturing method for an offshore wind turbine] First, with reference to Figures 1 to 8, an example of a method for manufacturing a floating foundation, a manufacturing system for a floating foundation, and a method for manufacturing an offshore wind turbine will be described. Here, Figure 1 is an overall perspective view of an example of a floating foundation manufacturing system according to the embodiment, Figure 2 is a perspective view of an example of a floating foundation manufactured by the floating foundation manufacturing method according to the embodiment, and Figure 3 is a perspective view of an example of an offshore wind turbine manufactured by the offshore wind turbine manufacturing method according to the embodiment. Furthermore, Figures 4A and 4B are process diagrams of an example of the floating foundation manufacturing method according to the first embodiment, respectively. Furthermore, Figure 5 is a diagram showing both an example of the floating foundation manufacturing method according to the second embodiment and an example of the floating foundation manufacturing method according to the third embodiment.

[0024] In addition, the diagrams omit illustrations of the reinforcing bars that form each concrete (reinforced concrete) component of the floating foundation, as well as illustrations of the tensioning members that form each component (connecting multiple elements together) or connect each component together.

[0025] The manufacturing system 60 shown in Figure 1 is installed at dock D and is a system for manufacturing floating foundations 70. The floating foundation 70 to be manufactured in the illustrated example is a semi-submersible type foundation, but the floating foundation manufactured by the manufacturing system 60 may be other types of floating foundations such as spar type, purge type, or TLP type.

[0026] The manufacturing system 60 includes multiple manufacturing yards 10 for manufacturing multiple types of divided parts that constitute a semi-submersible foundation 70, transport paths 50 provided between each manufacturing yard 10, transport means 30 for transporting the divided parts manufactured in each manufacturing yard 10 via the transport paths 50, and a connecting yard 20 for manufacturing a floating foundation 70 by connecting the divided parts that have been transported by the transport means 30.

[0027] Within Dock D, a sea platform S is deployed to the side of the quay P of connecting yard 20, where the fabricated floating foundation 70 will be towed and installed. A barge 90, loaded with the fabricated floating foundation 70, is moored at quay P for towing and installing it at the designated installation location.

[0028] As shown in Figure 2, the semi-submersible foundation 70 has a concrete center column 70A, three concrete side columns 70B arranged in three directions around the center column 70A at 120-degree intervals in a plan view, and three concrete pontoons 70C connecting the central center column 70A and each of the side columns 70B. The three directions at 120-degree intervals are the longitudinal directions of the pontoons 70C, and are therefore referred to as the pontoon axis directions.

[0029] Furthermore, the center column 70A comprises a center column base 71 and a center tower 72 rising from the center column base 71, while the side column 70B comprises a side column base 73 and a side tower 74 rising from the side column base 73.

[0030] 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.

[0031] These are manufactured as segments in various ways at their respective manufacturing yards 10, and each segment is transported to a connecting yard 20 and connected to create a floating foundation 70. Here, the semi-submersible foundation 70 to be manufactured has three side columns 70B, but although not shown in the illustration, it may also have a configuration in which four pontoons 70C are arranged at 90-degree intervals in a plan view around a center column 70A, and the side columns 70B are connected to each pontoon 70C.

[0032] As shown in Figure 2, each segment is placed on its own frame 40. Each frame 40 has a mounting plate 41, a plurality of legs 42 protruding from below the mounting plate 41, and an entry space 43 below the mounting plate 41 into which the transport means 30 enters.

[0033] Here, "a frame specific to each segment" means that, in addition to the number of frames 40 corresponding to each segment in a 1:1 ratio, if the number of frames 40 is small compared to the number of segments, and each segment is manufactured with a time lag between production, then one frame 40 will be repurposed for manufacturing and transporting multiple segments.

[0034] The center column 70A, side column 70B, and pontoon 70C are each mounted on their respective bases 40A, 40B, and 40D.

[0035] Returning to Figure 1, each fabrication yard 10 is located inside its own building 18. Each fabrication yard 10 is equipped with a gantry crane 15 for fabricating segmented parts, which is movable along multiple rails 13 in the X1 direction.

[0036] A frame 40 is installed in the production yard 10, and the segmented parts are manufactured on top of the frame 40.

[0037] Here, the divided structure can take various forms. Referring to Figure 2, the center column base 71 and the side column base 73 are included in the divided structure. In addition, the entire center tower 72 may be included in the divided structure, each center tower element 72a may be included, or a part of the center tower 72 (in an unfinished state) may be included. This also applies to the side towers 74.

[0038] Regarding the pontoon 70C, it may be included as a whole or as a part (in an unfinished state). Here, the pontoon 70C in the illustrated example is a connection of multiple pontoon elements 75a, but the pontoon may also be formed by individual pontoon elements.

[0039] The divided parts manufactured in the manufacturing yard 10 are manufactured on a frame 40, and then transported together with the frame 40 to the connecting yard 20 by a transport means 30. In the connecting yard 20, they are connected with other divided parts on the frame 40. Therefore, the form of the divided parts can vary depending on how far the manufacturing process is carried out on the frame 40 in the manufacturing yard 10.

[0040] For example, if the entire center column 70A is a segmented unit, the entire center column 70A is manufactured as a segmented unit on the frame 40 in the manufacturing yard 10. On the other hand, if the center column foundation 71 and the center tower 72 are manufactured on their respective frames 40 in their respective manufacturing yards 10, the center column foundation 71 and the center tower 72 are each manufactured as segmented units. Here, each center tower element 72a constituting 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 are placed on the frame 40 and tensioned by multiple tensioning members to manufacture the center tower 72. In this manufacturing method as well, the center tower 72 is a segmented unit.

[0041] In any case, in this specification, objects mounted on the frame 40 while being transported to the connecting yard 20 together with the frame 40 by the transport means 30 are referred to as "divided parts," and in addition to being 100% manufactured on the frame 40 (manufactured from start to finish), objects manufactured at locations other than the frame and then connected on the frame 40 are also included as "divided parts."

[0042] In each fabrication yard 10, concrete segments are manufactured as precast concrete (PCa) bodies, and in the connecting yard 20, each precast concrete segment is tensioned with tensioning members to create a floating foundation made of precast concrete (PCaPC).

[0043] Returning to Figure 1, in the illustrated example, the center column foundation 71, side column foundation 73, and pontoon 70C are fabricated on specific frames 40A, 40B, and 40D in their respective fabrication yards 10A, 10B, and 10D. As for the pontoon 70C, multiple pontoon elements 75a are fabricated at a location other than frame 40D in fabrication yard 10D, and then these multiple pontoon elements 75a are tensioned on frame 40D using multiple tensioning members to create the pontoon.

[0044] Furthermore, the center tower elements 72a and side tower elements 74a are manufactured in a common manufacturing yard 10C. The manufactured center tower elements 72a are connected to each other via tensioning members on a common frame 40, and similarly, the multiple side tower elements 74a are also connected to each other via tensioning members on the common frame 40 and transported together with the frame 40 to the connection yard 20. As previously mentioned, the center tower 72 and side towers 74 may be manufactured as separate parts on the frame 40 in an unfinished state, transported to the connection yard 20, and then sequentially stacked on the center column foundation 71 and side column foundation 73.

[0045] Figure 1 shows the state in which the side column foundation 73, which is placed on the frame 40B, is being transported in the X2 direction to the connecting yard 20 via the transport path 50 by the transport means 30, and also shows the state in which the pontoon 70C, which is placed on the frame 40D, is being transported in the X2 direction to the connecting yard 20 via the transport path 50.

[0046] In the connecting yard 20, a semi-submersible foundation 70 is fabricated by connecting each segment to each other via tensioning members on multiple frames 40, using heavy machinery 55 and other equipment as appropriate. Then, as shown in Figure 3, an offshore wind turbine 80 is fabricated by connecting a tower 82 equipped with a wind turbine 84 to the center column 70A that constitutes the semi-submersible foundation 70. Here, the illustrated example shows the tower 82 connected to the center column 70A, but a single tower or a wind turbine tower connected to the side column 70B may also be used.

[0047] Here, the methods for connecting the tower 82 to the semi-submersible foundation 70 include, as shown in Figure 1, connecting the tower 82 at the connection yard 20 while lifting it with heavy machinery 55; connecting the tower 82 to the semi-submersible foundation 70 installed at sea using a barge equipped with lifting machinery in the ocean; and transporting the semi-submersible foundation 70 to a barge 90 moored at the quay P, loading it, and then connecting the tower 82 from the quay P using heavy machinery. Furthermore, as will be explained below with reference to Figure 18, there is also a method of connecting the tower 82 from the quay P using heavy machinery while the semi-submersible foundation 70 is floating on the water beside the quay P, without using a barge.

[0048] Next, an example of a method for manufacturing a floating foundation according to the first embodiment will be described with reference to Figures 4A, 4B, and 2. Here, Figures 4A, 4B, and 2 are, in order, process diagrams of an example of a method for manufacturing a floating foundation according to the first embodiment.

[0049] In the illustrated example, the manufacturing method involves manufacturing the center column foundation 71 and the three side column foundations 73 as separate parts on a frame 40 in a dedicated manufacturing yard 10 (manufacturing process, separate part manufacturing process).

[0050] Next, each divided section is transported to the connecting yard 20 by a transport means 30 along with its own stand 40. In the connecting yard 20, the center column foundation 71 and the three side column foundations 73 are positioned along with the stands 40 on which they are placed, and a gap G for the pontoon 70C is provided between the center column foundation 71 and each side column foundation 73 for insertion (transport positioning process). Here, the process of transporting the divided sections together with the stands 40 from each manufacturing yard 10 can also be called the divided section transport process.

[0051] In other words, in the transport positioning process, the center column base 71 and each side column base 73 are positioned in a manner that eliminates the need for movement when connecting other divided parts thereafter.

[0052] Furthermore, the center column foundation 71, the side column foundation 73, and each pontoon 70C are all equipped with an upper deck 76, a lower deck 77, and left and right side walls 78, and have a hollow 79 inside that forms a ballast chamber. Multiple 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, the side column foundation 73, and each pontoon 70C, and tensioning members (not shown) are inserted through each sheath pipe and tensioned to connect the center column foundation 71, the side column foundation 73, and each pontoon 70C.

[0053] Next, as shown in Figure 4B, the pontoons 70C, which have been transported from the manufacturing yard 10 together with the frame 40D, are inserted in the Y1 direction into each pontoon gap G (pontoon insertion process).

[0054] Here, the width t1 of the pontoon gap G shown in Figures 4A and 4B is set to the length of the pontoon 70C plus the error length for manufacturing and / or connection errors. This makes it possible to reliably insert the pontoon 70C into the pontoon gap G between the positioned center column foundation 71 and the side column foundation 73, eliminating the need to move at least one of the positioned center column foundation 71 or side column foundation 73 if the pontoon 70C cannot be inserted.

[0055] Next, wet joints WJ, which are made by filling the gaps between the center column foundation 71 and the side column foundation 73 and the pontoon 70C with mortar or the like, are constructed, and these are then tensioned with tensioning material to connect the center column foundation 71 and the side column foundation 73 and the pontoon 70C (pontoon connection process). Here, from the viewpoint of watertightness, it is desirable to also construct wet joints WJ between mutually adjacent pontoon elements 75a, between center tower elements 72a, and between side tower elements 74a.

[0056] Next, the center tower 72 is connected to the center column foundation 71 while being lifted using heavy machinery 55, etc. (center tower connection process), and similarly, the side towers 74 are connected to each side column foundation 73 while being lifted using heavy machinery 55, etc. (side tower connection process), thereby manufacturing the semi-submersible foundation 70 shown in Figure 2. Here, the transport and positioning process, pontoon insertion process, pontoon connection process, center tower connection process, and side tower connection process can be collectively referred to as the connection process.

[0057] Although the illustration of each tensioning member is omitted here, the center column 70A is fabricated by tensioning the center column foundation 71 and center tower 72 with multiple first tensioning members, and the side column foundations 73 and side towers 74 are fabricated by tensioning each side column 70B with multiple second tensioning members. Furthermore, the pontoon 70C is fabricated in a dedicated fabrication yard 10C by tensioning multiple pontoon elements 75a with multiple third tensioning members. Then, in the pontoon connection process, the pontoon 70C is connected to the center column 70A and side columns 70B in the connection yard 20 by tensioning with multiple fourth tensioning members. Note that PC steel bars or PC steel wires are used for the first to fourth tensioning members.

[0058] Furthermore, in the fabrication of a semi-submersible foundation (not shown) in which four pontoons 70C are arranged at 90-degree intervals around a center column 70A, and side columns 70B are connected to each pontoon 70C, it is preferable that during the pontoon connection process, the third and fourth tensioning members be the same tensioning member, and that two opposing pontoons 70C are tensioned together with the center column foundation 71 using a common third tensioning member. This tensioning method allows for more efficient connections in the connection yard 20 by tensioning two opposing pontoons 70C together with the center column foundation 71 using a common third tensioning member.

[0059] According to the method for manufacturing the floating foundation according to the first embodiment shown in the figure, the transport and positioning process eliminates the need to move the center column foundation 71 and each side column foundation 73 when connecting other divided parts thereafter, thus enabling efficient connection of divided parts.

[0060] Furthermore, as shown in Figure 4B, by first manufacturing 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 construction safety.

[0061] Next, with reference to Figures 5 and 2, an example of a method for manufacturing a floating foundation according to the second and third embodiments will be described. Note that Figure 4A will be used to describe the manufacturing method according to the third embodiment.

[0062] The manufacturing method according to the second embodiment involves manufacturing the center column 70A on the frame 40A and the side columns 70B on the frame 40B at a dedicated manufacturing yard 10, then transporting these divided parts together with the frame 40 to the connection yard 20 for positioning, and inserting and connecting the pontoons 70C into each pontoon gap G.

[0063] This manufacturing method minimizes the number of connection steps required in the connection yard 20, thereby significantly improving the efficiency of connecting the divided sections in the connection yard 20.

[0064] Furthermore, the manufacturing method according to the third embodiment is similar to the method shown in Figure 4A, in which the center column foundation 71 and the three side column foundations 73 are positioned in the connecting yard 20 together with the frames 40 on which they are mounted, and then, as shown in Figure 5, the center tower 72 and the side towers 74 are connected to each foundation to manufacture the center column 70A and each side column 70B in advance, and finally, the pontoons 70C are inserted into each pontoon gap G and connected.

[0065] In addition, although not shown in the diagram, there is also a method in which the side column foundations 73 and side columns 70B are connected to the pontoon 70C in advance at the connection yard 20, and the three connecting parts are moved to connect to the center column foundation 71 and center column 70A. Furthermore, if the center column foundation 71 and part of the center tower 72 are manufactured as separate parts, and similarly the side column foundations 73 and part of the side tower 74 are manufactured as separate parts and transported to the connection yard 20, then the pontoon 70C will be connected to these, and the remaining center tower elements 72a of the center tower 72 and the remaining side tower elements 74a of the side tower 74 will be connected to them.

[0066] The manufacturing method for the offshore wind turbine according to the embodiment involves connecting the tower 82 to the semi-submersible foundation 70, which has been manufactured using the floating foundation manufacturing method according to the first to third embodiments or the other forms of floating foundation manufacturing method described above, at the connection yard 20 while lifting it with heavy machinery 55, as already explained. Alternatively, the manufactured semi-submersible foundation 70 may be towed out to sea and installed at sea, after which the tower 82 may be connected using a barge equipped with a lifting machine in the ocean. Furthermore, the semi-submersible foundation 70 may be transported to a barge 90 moored to the quay P, loaded, and then the tower 82 may be connected from the quay P using heavy machinery. In addition, as will be explained below with reference to Figure 18, there is also a method in which the semi-submersible foundation 70 floats on the water beside the quay P, without using a barge, and the tower 82 is connected from the quay P using heavy machinery.

[0067] Next, with reference to Figures 6 to 8, an example of a transport means and an example of a method for transporting the manufactured floating foundation in the connection step of the manufacturing method of the floating foundation according to the embodiment will be described. Here, Figure 6 is a perspective view of an example of a multi-axle trolley. Figure 7A shows the arrangement of multi-axle trolleys in the first method of transporting a floating foundation, where (a) is a plan view of multiple multi-axle trolleys transporting side columns, (b) is a plan view of multiple multi-axle trolleys transporting pontoons, and (c) is a plan view of multiple multi-axle trolleys transporting a center column. Figure 8A shows the arrangement of multi-axle trolleys in the second method of transporting a floating foundation, where (a), (b), and (c) are plan views of multiple multi-axle trolleys transporting side columns, (d), (e), and (f) are plan views of multiple multi-axle trolleys transporting pontoons, and (g) is a plan view of multiple multi-axle trolleys transporting a center column. Furthermore, Figures 7B and 8B illustrate examples of the first and second transport methods, respectively, in which a floating foundation is transported together with a frame using multiple multi-axle trolleys.

[0068] The illustrated transport means 30 is a multi-axle trolley, an example of a self-propelled trolley, equipped with a lifting mechanism that lifts the frame 40 and lifts it off the ground. The multi-axle trolley 30 has multiple axles 33 attached to a long body 31 in the axial direction (L direction), and multiple pairs of left and right wheels 35 are attached to each axle 33 at intervals in the axial direction of the body, and all wheels 35 are mounted on the corresponding axle 33 so as to be rotatable in the Y3 direction, and a loading platform 32 on top of the body 31 is mounted so as to be able to be raised and lowered by a lifting mechanism (not shown), thus forming the whole structure.

[0069] The multi-axle trolley 30 enters the access space 43 of each frame 40 shown in Figure 2, etc., with its loading platform 32 lowered, as shown in the illustrated example. When transporting the frame 40 together with the divided body, the loading platform 32 is raised by the lifting mechanism, thereby lifting the frame 40 off the ground.

[0070] Although not shown in the diagram, the transport means may be a frame 40 equipped with wheels driven by actuators, where these driven wheels are the transport means. Alternatively, the frame 40 may be equipped with wheels, and the transport means may be a towed trolley or a push-out trolley. Furthermore, the transport means may be a mobile lifting machine such as a crane.

[0071] The first method of transporting the floating foundation 70 shown in Figure 7 involves arranging each multi-axle bogie 30 in the connection process at the connection yard 20 such 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, and then connecting each segment to manufacture the semi-submergible foundation 70. Here, the body axis direction of each multi-axle bogie 30 does not have to be strictly oriented in these directions, but may also be oriented in a direction shifted by a few degrees.

[0072] Next, when loading out the semi-submersible foundation 70 along with multiple frames 40 using multiple multi-axle trolleys 30 and transporting it to the barge 90 moored at the quay P, all multi-axle trolleys 30 can be moved in the Y5 direction, which is the transport direction toward the barge 90, by controlling all wheels 35 of all multi-axle trolleys in the same direction or approximately the same direction. Here, controlling the wheels 35 in approximately the same direction means that there is an angular error of, for example, ±10 degrees with respect to a reference wheel angle along the Y5 direction, which is the load-out direction.

[0073] According to this transport method, when manufacturing a semi-submersible foundation 70 by connecting divided parts on multiple frames 40 in the connecting yard 20, or when the semi-submersible foundation 70 has been manufactured on multiple frames 40 (both are connection processes), all wheels 35 of all multi-axle bogies 30 are controlled in the same direction or approximately the same direction. This allows each multi-axle bogie 30 to be moved smoothly in the desired loadout direction without having to specify a fixed direction for its axial direction (L direction), making it possible to transport the semi-submersible foundation 70, including the frames 40, stably and smoothly and load it onto the barge 90. Furthermore, there is no need to change the plan view shape of the loading platform 32 of the multi-axle bogie 30 depending on its placement position. In other words, multi-axle bogies 30 equipped with loading platforms 32 of the same plan view shape can be used without being restricted by their placement position.

[0074] On the other hand, in the second transport method for the floating foundation 70 shown in Figure 8, during the connection process at the connection yard 20, each multi-axle trolley 30 is positioned with its body axis direction (L direction) facing the Y5 direction, which is the transport direction toward the barge 90, and each segment is connected to manufacture the semi-submersible foundation 70.

[0075] Next, when loading out the semi-submersible foundation 70 along with multiple frames 40 using multiple multi-axle trolleys 30 and transporting it to the barge 90 moored at the quay P, all of the multi-axle trolleys 30 can be moved in the Y5 direction, which is the transport direction toward the barge 90, by moving each multi-axle trolley 30 in a straight line.

[0076] According to this transport method, when manufacturing a semi-submersible foundation 70 by connecting divided parts on multiple frames 40 in the connecting yard 20, or when the semi-submersible foundation 70 has been manufactured on multiple frames 40 (both are connection processes), by moving in a straight line without controlling the angle of each wheel 35 to be in the same direction, it is possible to move smoothly in the desired loadout direction, and the semi-submersible foundation 70 including the frames 40 can be transported stably and smoothly and loaded onto the barge 90. Furthermore, in order to align the axis direction of the body of all multi-axle bogies 30 with the transport direction toward the barge 90, each multi-axle bogie 30 may need to be equipped with a loading platform 32 of various planar shapes depending on its position, as shown in the figure.

[0077] Next, with reference to Figures 9 to 17, an example of a method for launching a floating foundation according to the embodiment and an example of a method for recovering the frame on which the floating foundation is mounted will be described. Here, Figures 9 to 13 are sequential process diagrams of an example of a method for launching a floating foundation according to the embodiment. Figures 13 to 17 are sequential process diagrams of an example of a method for recovering a frame on which the floating foundation according to the embodiment is mounted.

[0078] As shown in Figure 9, the launching method for the floating foundation according to this embodiment involves mooring a barge 90 on the water S next to the quay wall P of the connecting yard 20 of dock D, and then, as previously described, manufacturing multiple concrete segments on their own unique frames 40, and connecting the multiple segments on the multiple frames 40 to manufacture a semi-submersible foundation 70.

[0079] Next, as shown in Figure 10, the semi-submersible foundation 70, along with the multiple support frames 40, is transported to the barge 90 in the Y7 direction by multiple multi-axle trolleys 30 and loaded. Each support frame 40 that has been transported to, for example, the deck of the barge 90 is fixed to the deck (this completes the transport process).

[0080] Following this transport 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. However, in this explanation, the tower 82 will be installed offshore.

[0081] After fixing each mounting frame 40 to the barge 90, as shown in Figure 11, all multi-axle trolleys 30 are moved (retracted) to the connecting yard 20 in the Y8 direction. Then, as shown in Figure 12, the barge 90, loaded with the semi-submersible foundation 70 along with the multiple mounting frames 40, is moved (towed) in the Y9 direction to the offshore wind turbine installation location at sea.

[0082] Next, as shown in Figure 13, the barge 90 is submerged in the Y10 direction, and the semi-submersible foundation 70 is launched into the water. Here, the barge 90 is submerged by injecting water into a ballast chamber (not shown) provided on the barge 90. Alternatively, if the barge 90 has support legs equipped with a lifting mechanism (not shown), it can be submerged by lowering the support legs (this concludes the launching process).

[0083] According to the floating foundation launching method shown in the illustration, efficient transport of the semi-submersible foundation 70 to the barge 90 can be achieved. After transport to the barge 90, the semi-submersible foundation 70 is towed to a predetermined position on the open sea and launched into the water, thereby achieving stable and smooth launching of the semi-submersible foundation 70.

[0084] On the other hand, the method for recovering the platform on which the floating foundation according to the embodiment is as shown in Figure 13, involves submerging the barge 90 in the Y10 direction with the semi-submersible foundation 70 mounted on the barge 90 together with multiple platforms 40 at the installation location of the semi-submersible foundation 70, and then, as shown in Figure 14, moving the barge 90 in the Y11 direction to a position away from the semi-submersible foundation 70.

[0085] Here, if the barge 90 is equipped with a ballast chamber (not shown), the barge 90 can be submerged by filling the ballast chamber with water, and the barge 90 can be raised by draining the ballast water from the ballast chamber. 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 raised by raising the lifting mechanism.

[0086] Next, as shown in Figure 15, a portion of the barge 90 is floated on the water in the Y12 direction, and as shown in Figure 16, the barge 90, equipped with multiple support structures 40, is pulled back towards the quay P in the Y13 direction (pulling back process).

[0087] After the barge 90, which had been pulled back, was moored at quay P, several multi-axle trailers 30 that had been waiting at connecting yard 20 were moved from quay P to barge 90 in the Y14 direction.

[0088] The multiple support structures 40 fixed to the deck of the barge 90 are released, multiple multi-axle trolleys 30 are moved into the corresponding access spaces 43 for the support structures 40, the loading platforms 32 are raised to lift the support structures 40 and remove them from the ground, and then, as shown in Figure 17, each multi-axle trolley 30 is moved from the barge 90 to the quay P in the Y15 direction, thereby recovering the multiple support structures 40 from the barge 90 to the quay P (this concludes the recovery process).

[0089] According to the method for recovering the floating foundations of the frames shown in the illustration, when recovering multiple frames 40, which are constructed by manufacturing multiple concrete segments and connecting them to form semi-submersible foundations 70, the barge 90 that has floated the semi-submersible foundations 70 on the water is pulled back to the quay P, then multiple multi-axle trolleys 30 are moved from the quay P to the barge 90, and the multiple frames 40 are recovered from the barge 90 to the quay P using the multiple multi-axle trolleys 30, thereby enabling efficient and reliable recovery of the frames 40.

[0090] Next, with reference to Figure 18, an example of a method for manufacturing and towing an offshore wind turbine according to the embodiment will be described. Here, Figure 18 is a diagram that mainly illustrates the method for manufacturing an offshore wind turbine among the methods for manufacturing and towing an offshore wind turbine.

[0091] In the illustrated example of the offshore wind turbine manufacturing and towing method, unlike the method of connecting the tower 82 (see Figure 3) to the semi-submersible foundation 70 at the connecting 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, as previously explained, the manufacturing of the offshore wind turbine is a method in which the semi-submersible foundation 70 is floating on the water to the side of the quay P, and the tower 82 is connected from the quay P.

[0092] In Figure 18, the dashed line shows the seabed B and quay P, as well as the water depth t5 and the draft t6 of the semi-submersible foundation 70, before water is poured into the ballast chamber 79A of the semi-submersible foundation 70. In contrast, the solid line shows the seabed B and quay P, as well as the water depth t7 and the draft t8 of the semi-submersible foundation 70, after water has been poured into the ballast chamber 79A. The water depths t5 and t7 remain virtually unchanged before and after water pouring.

[0093] The semi-submersible foundation 70, which is lowered onto the water from the quay P by a mobile lifting machine 56 (heavy equipment) such as a crane and moored to the quay P, has its ballast chamber 79A filled with water. This adjusts the draft t8 of the semi-submersible foundation 70 to be less than the water depth t7 at the quay P, while also lowering the level of the semi-submersible foundation 70 from the level before filling with water. This level adjustment allows the lifting height of the tower 82 by the heavy equipment 56 to be kept as low as possible, improving the connection of the tower to the floating foundation (preparation process).

[0094] Next, the offshore wind turbine 80 (see Figure 3) is fabricated by using heavy machinery 56 to lift and connect the tower 82 to the semi-submersible foundation 70, which is floating on the water.

[0095] Here, by adjusting the level of the semi-submersible foundation 70 to be lowered, it is also possible to make the semi-submersible foundation 70 rest on the seabed B to the side of the quay P.

[0096] This method allows the semi-submersible foundation 70 to be stabilized in an immovable position when connecting the tower 82, thereby improving the work rate when connecting the tower 82 to the semi-submersible foundation 70.

[0097] Furthermore, in addition to the method using the mobile lifting machine 56, the method of connecting the tower 82 to the semi-submersible foundation 70 may also be to erect the tower 82 using an erection device (not shown) located on the quay P and connect it to the semi-submersible foundation 70. In addition, the tower 82 may be connected to the semi-submersible foundation 70 using a self-elevating work barge (SEP vessel) on the water (the above describes the offshore wind turbine manufacturing process).

[0098] Next, after the offshore wind turbine 80 is manufactured next to the quay P, the ballast water is drained from the ballast chamber 79A of the semi-submersible foundation 70 to return the draft to the draft for towing, and then the offshore wind turbine is towed to its designated position offshore (towing process).

[0099] In this towing process, the semi-submersible foundation 70 can be towed in a stable position by increasing the draft by injecting ballast water into the ballast chamber 79A as needed.

[0100] According to the illustrated example of the offshore wind turbine manufacturing and towing method, water is injected into the ballast chamber 79A of the semi-submersible foundation 70 to reduce the draft of the semi-submersible foundation 70 to less than the water depth of the quay P, and the level of the semi-submersible foundation 70 is lowered. Then, the tower 82 is connected to the semi-submersible foundation 70 while it is floating on the water to manufacture the offshore wind turbine 80, thereby ensuring good connectivity between the tower 82 and the semi-submersible foundation 70. After that, the ballast water is drained from the ballast chamber 79A to return the draft to the draft suitable for towing, and then the offshore wind turbine 80 is towed to a predetermined position offshore, making it possible to safely tow the offshore wind turbine 80 to its predetermined position offshore.

[0101] Furthermore, other embodiments may be used in which other components are combined with the configurations listed in the above embodiments, and the present invention is not limited in any way to the configurations shown herein. In this regard, modifications can be made without departing from the spirit of the present invention, and can be appropriately determined according to the application form. [Explanation of Symbols]

[0102] 10, 10A, 10B, 10C, 10D: Manufacturing Yard 13: Rail 15: Gantry crane 18: Building 20: Connection Yard 30: Transport method (multi-axle trolley) 31: Vehicle body 32: Cargo bed 33: Axle 35: Wheels 40, 40A, 40B, 40C, 40D: Mounting frame 41: Mounted version 42: Legs 43: Approach space 50: Conveyor path 55: Heavy machinery (crane) 56: Mobile lifting equipment (cranes, heavy machinery) 60: Manufacturing System (Manufacturing system for floating foundations) 70: Floating foundation (semi-submersible type foundation) 70A: Center column (split) 70B: Side column (split) 70C: Pontoon (divided) 71: Center column basics (split form) 72: Center Tower (Divided) 72a: Center tower element (divided) 73: Side column basics (divided form) 74: Side Tower (Divided) 74a: Side Tower Element (Divided) 75a: Pontoon element (divided) 76:Upper floor version 77: Lower floor version 78: Side wall 79:Hollow 79A: Ballast Room 80: Offshore wind turbines 82: Tower 84: Windmill 90: Barge D: Doc P: Wharf S: On the open sea (on the ocean, on the water) G: Gap for pontoon WJ: Wet Joint B: Undersea

Claims

1. A method for manufacturing a floating foundation that supports the tower of an offshore wind turbine, comprising a concrete center column, a plurality of concrete side columns arranged at intervals in three or four directions around the center column, and a plurality of concrete pontoons connecting the center column and each side column, wherein the center column comprises a center column foundation and a center tower rising from the center column foundation, and the side columns comprise side column foundations and side towers rising from the side column foundations, and is a semi-submersible type foundation for supporting the tower of an offshore wind turbine. At a minimum, the process includes manufacturing the center column foundation, the side column foundation, and the pontoon as separate parts, and manufacturing each part on a stand in its respective manufacturing yard. A multi-axle trolley, unique to each of the aforementioned divided bodies, is placed beneath each of the aforementioned frames on which each divided body is mounted. The loading platform of the multi-axle trolley is raised to lift the frame off the ground, and the divided body is transported to the connecting yard by the multi-axle trolley, in a divided body transport process. The connection yard comprises a connection process in which each of the divided sections is mounted on the frame and connected to each other to manufacture the floating foundation, The aforementioned multi-axle bogie has multiple pairs of wheels mounted in the axial direction of the body on a long body, all of which are rotatably mounted on the body, and the loading platform on top of the body is mounted to be able to be raised and lowered by a lifting mechanism. A method for manufacturing a floating foundation, characterized in that, in the connection step, each multi-axle bogie is arranged so that the axial direction of the body of each multi-axle bogie is parallel to or perpendicular to at least one of the three or four pontoon axial directions, and all the wheels of all the multi-axle bogies are controlled in the same direction or substantially the same direction.

2. A method for manufacturing a floating foundation that supports the tower of an offshore wind turbine, comprising a concrete center column, a plurality of concrete side columns arranged at intervals in three or four directions around the center column, and a plurality of concrete pontoons connecting the center column and each side column, wherein the center column comprises a center column foundation and a center tower rising from the center column foundation, and the side columns comprise side column foundations and side towers rising from the side column foundations, and is a semi-submersible type foundation for supporting the tower of an offshore wind turbine. At a minimum, the process includes manufacturing the center column foundation, the side column foundation, and the pontoon as separate parts, and manufacturing each part on a stand in its respective manufacturing yard. A multi-axle trolley, unique to each of the aforementioned divided bodies, is placed beneath each of the aforementioned frames on which each divided body is mounted. The loading platform of the multi-axle trolley is raised to lift the frame off the ground, and the divided body is transported to the connecting yard by the multi-axle trolley, in a divided body transport process. The connection yard comprises a connection process in which each of the divided sections is mounted on the frame and connected to each other to manufacture the floating foundation, The aforementioned multi-axle bogie has multiple pairs of wheels mounted in the axial direction of the body on a long body, all of which are rotatably mounted on the body, and the loading platform on top of the body is mounted to be able to be raised and lowered by a lifting mechanism. A method for manufacturing a floating foundation, characterized in that, in the connection step, the vehicle axis direction of all the multi-axle bogies is set to the same direction or substantially the same direction.

3. The aforementioned connection step is A center tower connection step, which involves connecting the center tower to the center column foundation, A method for manufacturing a floating foundation according to claim 1 or 2, characterized by including a side tower connection step of connecting the side tower to the side column foundation.

4. The aforementioned process for manufacturing the divided body is, A center tower connection step, which involves connecting the center tower to the center column foundation, A method for manufacturing a floating foundation according to claim 1 or 2, characterized by including a side tower connection step of connecting the side tower to the side column foundation.

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