Manufacturing method of floating structures

Abstract

To provide a manufacturing method of a floating structure capable of accurately positioning multiple blocks on a floating dock.SOLUTION: The manufacturing method of a floating structure comprises an anchoring step to anchor a first block 21 to a floating dock 61 with multiple mooring lines 41 each of which extends toward an upper surface 621 of a bottom part 62 of the floating dock 61 from the first block 21, and a step of bringing the floating dock 61 to the surface and of attaching the first block 21 to the bottom part 62 of the floating dock 61 by adjusting each length of the multiple mooring lines 41 while adjusting the relative position with respect to the floating dock 61 of the first block 21. This allows accurate positioning of the multiple blocks on the floating dock 61.SELECTED DRAWING: Figure 9

Description

TECHNICAL FIELD

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

BACKGROUND ART

[0002] In recent years, floating offshore wind power generation facilities have been put into practical use, and an increase in power generation capacity is demanded. For example, in an offshore wind power generation facility having a power generation capacity of 10 MW or more, a floating structure on which a wind turbine is mounted becomes extremely large. For this reason, the floating structure cannot enter or exit a normal marine dry dock, even a dock for constructing cargo ships such as ultra-large crude oil carriers (ULCC) and ultra-large container ships, and must be constructed in a large dock for offshore structure construction.

[0003] For example, Patent Document 1 proposes a method for manufacturing a large floating structure by transporting a plurality of blocks manufactured in a small dock to a large dock and assembling the plurality of blocks in the large dock. According to this manufacturing method, the construction period in the large dock can be shortened. However, since the number of such large docks for offshore structure construction is small, mass production of the large floating structures as described above has a limit. In addition, constructing a new large dock requires a vast site and enormous costs.

[0004] On the other hand, Patent Document 2 discloses a technique of manufacturing a caisson on a floating dock floating on the sea, and then submerging the floating dock to launch the caisson.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0005]

PATENT DOCUMENT 1

PATENT DOCUMENT 2

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] Incidentally, when manufacturing large floating structures like the one described above on a floating dock, one possible method is to manufacture multiple blocks of the floating structure in a relatively small dry dock, and then assemble these multiple blocks on the floating dock. In this manufacturing method, the multiple blocks manufactured in the dry dock are towed across the ocean to above the submerged floating dock. Then, the floating dock is raised, and each block is supported on a platform provided on the bottom of the floating dock and lifted above the sea surface. After that, the multiple blocks are joined together to form a large floating structure.

[0007] The above manufacturing method requires aligning multiple blocks above a submerged floating dock. Furthermore, the relative positions of the multiple blocks must be maintained even when the floating dock is raised. However, unlike a dry dock where the gate is closed, the multiple blocks floating above the floating dock are susceptible to displacement due to external forces such as waves and currents, which may cause misalignment of the relative positions of the multiple blocks.

[0008] This invention has been made in view of the above problems, and aims to accurately align multiple blocks on a floating dock. [Means for solving the problem]

[0009] One aspect of the present invention is a method for manufacturing a floating structure, comprising the steps of: a) floating a floating dock having a bottom and a pair of side walls on the water surface with the upper surface of the bottom submerged in water, and b) After step a) above, The first block, which is part of the floating structure, is transported by water. The aforementioned first block, The steps of positioning the floating dock vertically above the bottom while it is floating on the water surface, and c) After step a) above, Multiple mooring lines extending from the first block toward the upper surface of the bottom of the floating dock, Floating on the water surface The steps of anchoring the first block to the floating dock and d) After step b) and step c), By adjusting the lengths of each of the aforementioned mooring lines, Floating on the water surface e) The steps of adjusting the relative position of the first block with respect to the floating dock, raising the floating dock to allow the first block to settle on the bottom of the floating dock, and After step d) above, The method includes the step of further raising the floating dock to support the first block above the water surface, in a state where it is aligned with the second block, which is another part of the floating structure, on the bottom of the floating dock.

[0010] Aspect 2 of the present invention is a method for manufacturing a floating structure according to aspect 1, wherein the number of the plurality of mooring lines is four or more.

[0011] A third aspect of the present invention is a method for manufacturing a floating structure according to aspect 1 (or aspect 1 or 2), wherein a plurality of fixing members are provided on the upper surface of the bottom of the floating dock, to which the ends of the plurality of mooring lines are each fixed.

[0012] Aspect 4 of the present invention is a method for manufacturing a floating structure according to aspect 1 (which may be any one of aspects 1 to 3), wherein the length adjustment of each of the plurality of mooring lines in step d) is performed using a line length adjustment mechanism located on the first block.

[0013] Aspect 5 of the present invention is a method for manufacturing a floating structure according to aspect 1 (or aspect 1 or 2), wherein each of the plurality of mooring lines extends from the first block, through the upper surface of the bottom of the floating dock, toward one of the pair of side walls of the floating dock. The lines are connected to one of a plurality of line length adjustment mechanisms provided on the pair of side walls. The length adjustment of the plurality of mooring lines in step d) is performed using the plurality of line length adjustment mechanisms.

[0014] Aspect 6 of the present invention is a method for manufacturing a floating structure according to aspect 5, wherein a position measuring unit for measuring the relative position of the first block with respect to the floating dock is provided on the floating dock or the first block. In step d), the plurality of line length adjustment mechanisms are automatically controlled based on the output from the position measuring unit.

[0015] Aspect 7 of the present invention is a method for manufacturing a floating structure according to any one of aspects 1 to 6, wherein between step a) and step d), the second block is transported by water and positioned vertically above the bottom of the floating dock while floating on the water surface, and the second block is anchored to the floating dock by a plurality of mooring lines extending from the second block toward the upper surface of the bottom of the floating dock. In step d), the second block is brought to the bottom of the floating dock while adjusting the relative position of the second block with respect to the floating dock by adjusting the lengths of the plurality of mooring lines extending from the second block.

[0016] Aspect 8 of the present invention is a method for manufacturing a floating structure according to aspect 7, wherein the first block and the second block are each manufactured in a small dock having a width less than the buildable width, which is the width through which the floating structure can enter and exit. The width between the pair of side walls of the floating dock is greater than or equal to the buildable width.

[0017] Aspect 9 of the present invention is a method for manufacturing a floating structure according to any one of aspects 1 to 6 (or any one of aspects 1 to 8), wherein the floating structure is a floating body that supports a wind turbine for power generation in a floating offshore wind power generation system. [Effects of the Invention]

[0018] This invention enables highly accurate alignment of multiple blocks on a floating dock. [Brief explanation of the drawing]

[0019] [Figure 1] It is a perspective view of a floating structure. [Figure 2] It is a plan view of the first block, the second block, and the third block. [Figure 3] It is a plan view of a floating structure. [Figure 4] It is a diagram showing the manufacturing process of a floating structure. [Figure 5] It is a plan view showing the first block, the second block, and the third block in a small dock. [Figure 6] It is a front view of the floating dock. [Figure 7] It is a plan view of the floating dock. [Figure 8] It is a plan view of the floating dock, and the first block, the second block, and the third block. [Figure 9] It is a front view of the floating dock, and the first block, the second block, and the third block. [Figure 10] It is a front view of the floating dock, and the first block, the second block, and the third block. [Figure 11] It is a front view of the floating dock, and the first block, the second block, and the third block. [Figure 12] It is a front view of the floating dock and the first block. [Modes for Carrying Out the Invention]

[0020] First, the manufacturing method of the floating structure according to the first embodiment of the present invention (hereinafter also referred to as "the first manufacturing method") will be described. In the following, the manufacturing method will be described taking the floating structure 1 shown in a perspective view in FIG. 1 as an example. The floating structure 1 is a large floating body that supports a power generation wind turbine from below in a state of floating on the water surface (that is, the sea surface) in a floating offshore wind power generation system.

[0021] The floating structure 1 illustrated in Figure 1 is a lower-hull type semi-submersible floating structure. The floating structure 1 comprises four columns 11 and a lower hull 12. The four columns 11 are erected on the lower hull 12. One of the four columns 11 is located approximately in the center of the floating structure 1 in a plan view, and the other three columns 11 are arranged around this one column 11. These three columns 11 are, for example, approximately the same shape. The central column 11 may be approximately the same shape as the other three columns 11, or it may have a different shape.

[0022] Each column 11 is a roughly columnar member that extends roughly parallel and in a roughly straight line upward from the lower hull 12, penetrating the sea surface. In other words, the draft of the floating structure 1 is located between the upper and lower ends of each column 11. In the example shown in Figure 1, each column 11 is a roughly cylindrical member. The shape of the column 11 can be changed in various ways, such as a rectangular prism. The support column (also called a tower) of the aforementioned wind turbine for power generation (not shown) is erected, for example, at the upper end of the central column 11.

[0023] The lower hull 12 is a component connected to the lower part of the four columns 11. The lower hull 12 is almost entirely submerged in water (i.e., in the sea) and supports its own weight and the weight of the columns 11, etc., by buoyancy. A ballast tank (not shown) is provided inside the lower hull 12, and by adjusting the amount of water inside the ballast tank, the vertical position of the lower hull 12 in the sea (i.e., the height of the columns 11 protruding from the sea surface) and the attitude of the lower hull 12 are adjusted.

[0024] In the example shown in Figure 1, the lower hull 12 comprises a central hull section 122 and three hull sections 121. The three hull sections 121 extend radially in a substantially horizontal direction from the lower end of the central column 11. The three hull sections 121 are substantially the same shape and are arranged at substantially equal angular intervals in the circumferential direction (hereinafter also simply referred to as the "circumferential direction") with respect to the central axis of the central column 11. Each hull section 121 is a substantially columnar portion that extends substantially in a substantially straight line substantially parallel to the radial direction (hereinafter also simply referred to as the "radial direction") with respect to the central axis of the central column 11.

[0025] In the example shown in Figure 1, each hull section 121 is a roughly rectangular prism-shaped part. The cross-sectional shape of each hull section 121 perpendicular to the longitudinal direction (i.e., radial direction) is roughly rectangular, and for example, it is roughly the same along the approximately entire length in the longitudinal direction. The shape of each hull section 121 can be changed in various ways, such as to be cylindrical. The central hull section 122 is connected to the lower end of the central column 11 and connects the radially inner ends of the three hull sections 121. The three columns 11, excluding the central column 11, are connected to the radially outer ends (i.e., the tip) of the three hull sections 121.

[0026] In the example shown in Figure 1, the vertical height of the floating structure 1 (hereinafter also simply referred to as "height") is approximately 30m to 40m. The height of the lower hull 12 is approximately 5m to 10m, and the height of each column 11 is approximately 25m to 30m. The diameter of each column 11 is approximately 10m to 20m. The wind turbine mounted on the central column 11 is, for example, a wind turbine with a power generation capacity of 15MW. The width of the hull portion 121 of the lower hull 12 (i.e., the direction perpendicular to the upper direction and the longitudinal direction mentioned above) is approximately 12m to 20m, and the length in the longitudinal direction (i.e., the shortest radial distance from the radial outer end of the hull portion 121 to the outer surface of the central column 11) is approximately 40m to 60m. Note that the size and shape of the floating structure 1 can be varied.

[0027] In Figure 1, if the longitudinal and width directions of one hull section 121 extending to the right from the central column 11 are defined as the longitudinal and width directions of the floating structure 1, respectively, then the longitudinal length of the floating structure 1 is approximately 100 m, and the width in the width direction (i.e., the shortest distance between the radial outer ends of the two hull sections 121 located to the left of column 11) is approximately 100 m. The length, width, and height of each part of the floating structure 1 can be varied.

[0028] When the floating structure 1 is manufactured, in general, several blocks that will become part of the floating structure 1 are manufactured in a small dry dock, and these blocks are transported by water (i.e., by sea) to a single floating dock. There, the multiple blocks are joined together (i.e., assembled) to manufacture the floating structure 1. This allows for the efficient manufacture of the floating structure 1 without the need to prepare an extra-large dry dock or a vast onshore yard.

[0029] In the specific example of the manufacturing method described later, as shown in Figure 2 (plan view), the floating structure 1 is manufactured in a state divided into three blocks 21 to 23. Then, as shown in Figure 3 (plan view), the three blocks 21 to 23 are joined together to form the floating structure 1. Block 21 comprises a central hull portion 122, one hull portion 121, and two columns 11 connected to the radially outer ends of the central hull portion 122 and the hull portion 121, respectively. Blocks 22 and 23 each comprise one hull portion 121 and one column 11 connected to the radially outer end of the hull portion 121. For convenience, in the following description, blocks 21 to 23 will be referred to as "first block 21," "second block 22," and "third block 23," respectively.

[0030] The division of the floating structure 1 is not limited to the example shown in Figure 2 and can be modified in various ways. For example, the joint between the first block 21 and the second block 22 does not need to be located at the boundary between the hull center 122 and the hull section 121, but may be located in the longitudinal center of the hull section 121, or the like. The same applies to the joint between the first block 21 and the third block 23. Also, the hull center 122 may be included in the second block 22 or the third block 23 instead of the first block 21. The number of blocks constituting the floating structure 1 does not need to be three; it may be two or four or more.

[0031] The small docks mentioned above are dry docks for building cargo ships such as crude oil tankers and container ships, and are, for example, ordinary marine docks with a width of 75m or less (i.e., gate width). Small docks are, for example, dry docks or slipways. Floating docks have a width greater than floating structure 1 (for example, greater than 75m). As mentioned above, the width of floating structure 1 illustrated in Figure 1 is approximately 100m, so it is impossible for floating structure 1 to enter or leave the small dock. Furthermore, since the length of floating structure 1 is also approximately 100m, even if the orientation of floating structure 1 were changed, it would still be impossible for floating structure 1 to enter or leave the small dock.

[0032] Next, the manufacturing process of the floating structure 1 will be explained in detail with reference to Figure 4, etc. When the floating structure 1 is manufactured, first, as shown in Figure 5 (plan view), the first block 21, the second block 22, and the third block 23, each being part of the floating structure 1, are manufactured in a small dock 71 with the gate 711 closed and drained (i.e., in a dry state) (step S11). In Figure 5, parallel diagonal lines are drawn to the water (i.e., seawater) outside the gate 711 of the small dock 71 to facilitate understanding of the figure. As described above, the small dock 71 has a width less than the width through which the floating structure 1 can enter and exit (hereinafter also referred to as the "construction-possible width"). The width of the small dock 71 is, for example, 75m or less. In the example shown in Figure 5, the first block 21, the second block 22, and the third block 23 are manufactured in one small dock 71, but they may be manufactured separately in multiple small docks.

[0033] Once the manufacturing of the first block 21, the second block 22, and the third block 23 is completed, water is poured into the small dock 71, causing the first block 21, the second block 22, and the third block 23 to float. The first block 21, the second block 22, and the third block 23 are then sequentially removed from the small dock 71 by passing through the open gate 711 using tugboats or the like. A floating dock is already positioned on the sea (step S12), and the first block 21, the second block 22, and the third block 23 are towed to the floating dock while floating on the surface of the sea.

[0034] Furthermore, the maritime transport of Block 1 21, Block 2 22, and Block 3 23 is not limited to towing while floating on the sea surface, but may be carried out by various other methods. For example, Block 1 21 may be transported by sea on a self-propelled barge, or it may be towed by a tugboat while loaded on a non-self-propelled barge. The same applies to Block 2 22 and Block 3 23.

[0035] Figure 6 is a front view showing the floating dock 61. Figure 7 is a top view showing the floating dock 61. The floating dock 61 comprises a bottom portion 62 and a pair of side wall portions 63. The bottom portion 62 is a roughly rectangular parallelepiped portion that extends substantially perpendicular to the vertical direction. In a plan view, the shape of the bottom portion 62 is, for example, roughly rectangular. The pair of side wall portions 63 are erected upward from the bottom portion 62 and are roughly rectangular parallelepiped portions that extend substantially perpendicular to the left-right direction in Figure 6 (hereinafter also simply referred to as the "left-right direction"). In a side view, the shape of each side wall portion 63 is, for example, roughly rectangular. The shape of the pair of side wall portions 63 is, for example, substantially the same. The pair of side wall portions 63 are provided on the bottom portion 62, along both side edges of the bottom portion 62 in the left-right direction. As shown in Figure 6, the bottom portion 62 and the pair of side wall portions 63 have a roughly rectangular shape when viewed from the front, and the bottom portion 62 and the pair of side wall portions 63 extend in a direction perpendicular to the plane of the paper in Figure 6 (hereinafter also referred to as the "front-to-back direction").

[0036] The floating dock 61 has a length of approximately 140m to 160m in the left-right direction and a length of approximately 120m to 140m in the front-rear direction. The distance between the inner surfaces of the pair of side walls 63 in the left-right direction (i.e., the width between the pair of side walls 63) is greater than or equal to the above-mentioned buildable width, for example, greater than 100m. The height of the bottom 62 in the vertical direction is approximately 3m to 6m, and the height of each side wall 63 in the vertical direction is approximately 10m to 15m.

[0037] In the state shown in Figure 6, the floating dock 61 floats on the sea without touching the seabed (i.e., the bottom), with the upper surface 621 of its bottom 62 submerged in the sea (i.e., located below the sea surface 91). This state is achieved by filling a ballast tank (not shown) located inside the floating dock 61 with water. The pair of side walls 63 penetrate the sea surface 91. In other words, the upper parts of the pair of side walls 63 are located above the sea surface 91. The floating dock 61 may also be in contact with the seabed.

[0038] Multiple support frames (also called wooden blocks) 64 are fixed in predetermined positions on the upper surface 621 of the bottom 62 of the floating dock 61. Each of the multiple support frames 64 is a block support part that contacts and supports the first block 21, the second block 22, or the third block 23 from below, as will be described later. The arrangement of the multiple support frames 64 may be changed as appropriate.

[0039] Furthermore, multiple fixing members 65 are provided on the upper surface 621 of the bottom 62 of the floating dock 61, to which the ends of multiple mooring lines 41 are each fixed. Note that the mooring lines 41 are not shown in Figure 7. The fixing members 65 and the mooring lines 41 are components for connecting (i.e., anchoring) the first block 21, the second block 22, and the third block 23 to the bottom 62 of the floating dock 61 in a state where their movement is restricted. The fixing members 65 are, for example, approximately semicircular, retractable fittings provided on the upper surface 621 of the bottom 62 of the floating dock 61. One or more ends of mooring lines 41 (hereinafter also referred to as "lower ends") are connected to each fixing member 65.

[0040] The mooring line 41 is a substantially linear member that connects each of the first block 21, the second block 22, and the third block 23 to the bottom 62 of the floating dock 61. The mooring line 41 is, for example, a mooring rope, a mooring chain, or a mooring chain and a mooring rope connected together. The mooring rope is, for example, a rope made of synthetic fiber or a metal rope containing wire. In the following description, the mooring line 41 will be described as a metal rope.

[0041] A small buoy 42 is connected to the other end of each mooring line (i.e., the end opposite to the side connected to the fixing member 65, hereinafter also referred to as the "upper end") via a messenger rope or the like, and the small buoy 42 floats on the sea surface 91. Each mooring line 41 extends upward from the upper surface 621 of the bottom 62 of the floating dock 61 toward the sea surface 91.

[0042] The first block 21, the second block 22, and the third block 23, which have been towed to the floating dock 61, are positioned between a pair of side walls 63 using a tugboat or the like. The first block 21, the second block 22, and the third block 23 are positioned vertically above the bottom 62 of the floating dock 61, floating on the sea surface 91, near their predetermined positions in a plan view (step S13).

[0043] Next, as shown in Figure 8 (plan view) and Figure 9 (front view), workers (not shown) positioned on the first block 21, the second block 22, and the third block 23 respectively connect the upper ends of the multiple mooring lines 41 to the multiple line length adjustment mechanisms 24 that are pre-installed on the first block 21, the second block 22, and the third block 23. Specifically, the workers use a hand hook or the like to pull in a small buoy 42 (see Figure 6) to retrieve the upper end of the mooring line 41 and connect the upper end to the line length adjustment mechanism 24.

[0044] The line length adjustment mechanism 24 is, for example, a load tensioner such as a chain hoist. The line length adjustment mechanism 24 is temporarily installed on the upper surface of the hull portion 121 of the first block 21, the second block 22, and the third block 23 in a removable manner. Note that a mechanism other than a load tensioner may be used as the line length adjustment mechanism 24. Furthermore, the line length adjustment mechanism 24 may remain on the first block 21, the second block 22, and the third block 23 even after the manufacturing of the floating structure 1 is completed.

[0045] The first block 21 is anchored (i.e., moored) to the bottom 62 of the floating dock 61 by a plurality of mooring lines 41 extending in different directions from the first block 21 toward the upper surface 621 of the bottom 62 of the floating dock 61. The second block 22 is also anchored to the bottom 62 of the floating dock 61 by a plurality of mooring lines 41 extending in different directions from the second block 22 toward the upper surface 621 of the bottom 62 of the floating dock 61. The third block 23 is also anchored to the bottom 62 of the floating dock 61 by a plurality of mooring lines 41 extending in different directions from the third block 23 toward the upper surface 621 of the bottom 62 of the floating dock 61 (step S14).

[0046] In the example shown in Figure 8, the first block 21, the second block 22, and the third block 23 are each anchored to the floating dock 61 by four mooring lines 41. The mooring line 41 extending from the upper right end of the first block 21 in Figure 8 is connected to the same fixing member 65 as the mooring line 41 extending from the second block 22. Similarly, the mooring line 41 extending from the upper left end of the first block 21 in Figure 8 is connected to the same fixing member 65 as the mooring line 41 extending from the third block 23.

[0047] In addition, the number of mooring lines 41 used for anchoring may be the same or different in the first block 21, the second block 22, and the third block 23. The number of mooring lines 41 used for anchoring in the first block 21 may be two, but preferably three or more, and more preferably four or more. The same applies to the second block 22 and the third block 23. In the state shown in Figures 8 and 9, the first block 21, the second block 22, and the third block 23 are not in direct contact with the bottom 62 of the floating dock 61 (specifically, the multiple support structures 64 provided on the upper surface 621 of the bottom 62).

[0048] In this embodiment, as described above, the first block 21, the second block 22, and the third block 23 are positioned vertically above the bottom 62 of the floating dock 61 before anchoring is performed, but this is not limited to this. For example, after the placement of the first block 21 above the floating dock 61 (step S13) is completed, the placement and anchoring of the second block 22 above the floating dock 61 may be performed in parallel with the anchoring of the first block 21 (step S14), or after the anchoring of the first block 21 (step S14) is completed. The same applies to the third block 23. That is, the placement and anchoring of the second block 22 and the third block 23 above the floating dock 61 may be performed between step S12 described above and step S15 described later.

[0049] When step S14 is completed, the worker operates each of the line length adjustment mechanisms 24 on the first block 21 to adjust the length of each of the multiple (four in the above example) mooring lines 41 connected to the first block 21. For example, by shortening the length of one mooring line 41, the first block 21 can be displaced in plan view so that it is closer to the fixing member 65 to which the lower end of that mooring line 41 is connected, or rotated in plan view so that it faces the fixing member 65.

[0050] The length of each mooring line 41 is adjusted, for example, based on the position and orientation of the first block 21 obtained by visual inspection by a worker or supervisor. The same applies to the position adjustment of the second block 22 and the third block 23, which will be described later. This adjusts the position of the first block 21 in a plan view, and adjusts the relative position of the first block 21 with respect to the floating dock 61 to a predetermined position (step S15). The length of the mooring line 41 refers to the length of the portion of the mooring line 41 between the line length adjustment mechanism 24 and the fixing member 65 of the floating dock 61.

[0051] In step S15, the worker operates each of the multiple line length adjustment mechanisms 24 on the second block 22 to adjust the length of each of the multiple (four in the above example) mooring lines 41 connected to the second block 22. This adjusts the position of the second block 22 in plan view, and adjusts its relative position to the floating dock 61 to a predetermined position. It also adjusts the relative position of the second block 22 to the first block 21 so that it can be joined.

[0052] In step S15, similarly for the third block 23, the multiple line length adjustment mechanisms 24 on the third block 23 are operated by the worker to adjust the length of each of the multiple (four in the above example) mooring lines 41 connected to the third block 23. This adjusts the position of the third block 23 in plan view, and adjusts the relative position of the third block 23 with respect to the floating dock 61 to a predetermined position. In addition, the relative position of the third block 23 with respect to the first block 21 is adjusted so that it can be joined.

[0053] In other words, in step S15, the lengths of the multiple mooring lines 41 are adjusted to align the first block 21, the second block 22, and the third block 23. After alignment, the first block 21 and the second block 22, and the first block 21 and the third block 23 are temporarily joined using, for example, a temporary joint (not shown) to maintain their relative positions. Note that in Figures 8 and 9, larger gaps are depicted between the first block 21 and the second block 22, and between the first block 21 and the third block 23 than are actually there (the same applies to Figures 10 and 11, which will be described later).

[0054] Next, the ballast tank of the floating dock 61 is drained, and the floating dock 61 rises from the state shown in Figure 9. As a result, the floating dock 61 moves upward relative to the first block 21, the second block 22, and the third block 23. Then, as shown in Figure 10 (front view), the multiple support structures 64 provided on the bottom 62 of the floating dock 61 come into contact with the bottom surfaces of the first block 21, the second block 22, and the third block 23, respectively, and the first block 21, the second block 22, and the third block 23 are placed on the multiple support structures 64. In other words, the first block 21, the second block 22, and the third block 23 settle on the bottom 62 of the floating dock 61 (step S16).

[0055] In step S16, from the start of the floating dock 61's ascent until the first block 21, second block 22, and third block 23 settle to the bottom, a number of line length adjustment mechanisms 24 on the first block 21, second block 22, and third block 23 are operated by a worker to adjust the length of each of the mooring lines 41 extending from the first block 21, second block 22, and third block 23. Specifically, the length of each mooring line 41 is shortened as the floating dock 61 ascends. This suppresses or prevents slack in the mooring lines 41, and adjusts the relative positions of the first block 21, second block 22, and third block 23 with respect to the floating dock 61 in a plan view, and the relative positions of the first block 21, second block 22, and third block 23 with respect to each other in a plan view, so as to maintain predetermined positions.

[0056] The floating dock 61 continues to rise even after the first block 21, second block 22, and third block 23 come into contact with the multiple support structures 64, and stops when the upper surface 621 of the bottom 62 of the floating dock 61 is above the sea surface 91, as shown in Figure 11 (front view). Seawater on the bottom 62 of the floating dock 61 flows out from the front and rear ends of the floating dock 61, and seawater is removed from the upper surface 621 of the bottom 62. As a result, the bottom 62 of the floating dock 61 becomes dry, and the first block 21, second block 22, and third block 23 are supported above the sea surface 91 (step S17).

[0057] Then, the connection between the first block 21, second block 22, and third block 23 and the bottom 62 of the floating dock 61 by multiple mooring lines 41 is released, and the multiple line length adjustment mechanisms 24 are removed from the first block 21, second block 22, and third block 23. After that, work such as joining (i.e., final joining) and painting of the first block 21, second block 22, and third block 23 is carried out on the bottom 62 of the floating dock 61, and the floating structure 1 is manufactured (step S18). Note that the removal of the multiple line length adjustment mechanisms 24 may be carried out in parallel with step S18.

[0058] As described above, the manufacturing method of the floating structure 1 includes the steps of: floating a floating dock 61 having a bottom 62 and a pair of side wall portions 63 on the water with the upper surface 621 of the bottom 62 submerged in water (step S12); transporting a first block 21, which is part of the floating structure 1, on the water and positioning it vertically above the bottom 62 of the floating dock 61 while floating on the water surface 91 (sea surface 91) (step S13); and anchoring the first block 21 to the floating dock 61 by a plurality of mooring lines 41 that extend from the first block 21 toward the upper surface 621 of the bottom 62 of the floating dock 61. The process includes: a step of setting up (step S14); a step of adjusting the relative position of the first block 21 with respect to the floating dock 61 by adjusting the lengths of the multiple mooring lines 41, while raising the floating dock 61 to allow the first block 21 to settle on the bottom 62 of the floating dock 61 (step S16); and a step of further raising the floating dock 61 to support the first block 21 above the water surface 91 while aligning it with the second block 22, which is another part of the floating structure 1, on the bottom 62 of the floating dock 61 (step S17).

[0059] In this manufacturing method, by anchoring the first block 21 to the bottom 62 of the floating dock 61 and adjusting its position, the relative position of the first block 21 with respect to the floating dock 61 can be adjusted with high precision, even on the floating dock 61 which is affected by waves and currents. This allows for high-precision alignment of multiple blocks on the floating dock 61 (for example, alignment of the first block 21 and the second block 22). As a result, adjustment of the relative positions between the blocks after they have settled can be omitted or suppressed. Therefore, the joining of multiple blocks can be facilitated, and the manufacturing of the floating structure 1 can be simplified.

[0060] Preferably, the number of the multiple mooring lines 41 described above (i.e., multiple mooring lines 41 extending from the first block 21 toward the upper surface 621 of the bottom 62 of the floating dock 61) is four or more. This allows for easy and accurate positional adjustment of the first block 21 by adjusting the length of the mooring lines 41. The same applies to the second block 22 and the third block 23.

[0061] As described above, it is preferable that the upper surface 621 of the bottom 62 of the floating dock 61 is provided with a plurality of fixing members 65 to which the ends of the plurality of mooring lines 41 (i.e., the lower ends of the plurality of mooring lines 41 extending from the first block 21) are each fixed. This simplifies the anchoring structure of the first block 21. The same applies to the second block 22 and the third block 23.

[0062] In step S16, it is preferable to adjust the length of each of the multiple mooring lines 41 using a line length adjustment mechanism 24 located on the first block 21. This makes it easy to adjust the relative position of the first block 21 with respect to the floating dock 61. Furthermore, the line length adjustment mechanism 24 can be easily positioned in an appropriate location (for example, a position where the multiple mooring lines 41 do not intersect) in accordance with the shape of the first block 21 and the arrangement of the fixing members 65 at the bottom 62 of the floating dock 61. The same applies to the second block 22 and the third block 23.

[0063] In the above-described method for manufacturing the floating structure 1, it is preferable that between step S12 and step S15, the second block 22 is transported on the water surface 91 and positioned vertically above the bottom 62 of the floating dock 61 while floating on the water surface 91, and that the second block 22 is anchored to the floating dock 61 by a plurality of mooring lines 41 that extend from the second block 22 toward the upper surface 621 of the bottom 62 of the floating dock 61. Furthermore, in step S15, it is preferable to adjust the relative position of the second block 22 with respect to the floating dock 61 by adjusting the lengths of the plurality of mooring lines 41 extending from the second block 22, and to make the second block 22 settle on the bottom 62 of the floating dock 61.

[0064] This allows for precise adjustment of the relative position of the second block 22 with respect to the floating dock 61 and the first block 21, even on the floating dock 61 which is affected by waves and currents. As a result, the alignment of the first block 21 and the second block 22 on the floating dock 61 can be performed with even greater precision. The same applies to the third block 23.

[0065] As described above, it is preferable that the first block 21 and the second block 22 are each manufactured in a small dock 71 having a width less than the buildable width, which is the width that allows the floating structure 1 to enter and exit the dock. Furthermore, the width between the pair of side walls 63 of the floating dock 61 is greater than or equal to the buildable width. This allows for efficient manufacturing of the floating structure 1 without having to prepare an extra-large dry dock or a vast land yard, as described above. In addition, the floating structure 1 can be manufactured in a location relatively close to the water area where it will be installed. As a result, the cost and time required to transport the floating structure 1 to the water area can be reduced. It is also more preferable that the third block 23 be manufactured in the small dock 71 described above.

[0066] The floating structure 1 is preferably a floating structure that supports a wind turbine in a floating offshore wind power generation system. Since such a floating structure 1 is very large, it is generally necessary to manufacture it in a very large dry dock or a vast onshore yard. In contrast, the above-described method for manufacturing the floating structure 1 does not require a very large dry dock or a vast onshore yard, and therefore this manufacturing method is particularly suitable for manufacturing a floating structure that supports the wind turbine mentioned above.

[0067] Next, a method for manufacturing the floating structure 1 according to a second embodiment of the present invention (hereinafter also referred to as the "second manufacturing method") will be described. The second manufacturing method for the floating structure 1 is substantially the same as the first manufacturing method described above (steps S11 to S18), except that the manner of anchoring and position adjustment of the first block 21, the second block 22, and the third block 23 in steps S14 to S16 (see Figure 4) is different.

[0068] Figure 12 is a front view showing a part of the floating structure 1 under construction using the second manufacturing method. In Figure 12, the first block 21, floating on the sea surface 91 spaced upward from the bottom 62 of the floating dock 61, is anchored to the bottom 62 of the floating dock 61 in a manner different from the first manufacturing method described above (see Figure 9). Although the second block 22 and the third block 23 are not shown in Figure 12, the second block 22 and the third block 23 are also anchored to the bottom 62 of the floating dock 61 in substantially the same manner as the first block 21. Furthermore, in order to facilitate understanding of the figure, the configurations related to the anchoring and bottoming of the second block 22 and the third block 23 are also not shown in Figure 12.

[0069] In the second manufacturing method, multiple line length adjustment mechanisms 24a are provided on each side wall 63 of the floating dock 61. Figure 12 shows one line length adjustment mechanism 24a provided on each side wall 63. The line length adjustment mechanism 24a is, for example, an electric or hydraulic winch. Each line length adjustment mechanism 24a is positioned, for example, above the sea surface 91. In the example shown in Figure 12, no line length adjustment mechanisms 24 such as the above-mentioned load tensioners (see Figure 9) are provided on the first block 21, and instead, a locking part 25a such as a bollard is provided to lock the end (i.e., upper end) of the mooring line 41.

[0070] In the second manufacturing method, a plurality of steering members 65a are provided on the upper surface 621 of the bottom 62 of the floating dock 61. The steering members 65a are, for example, substantially semicircular retractable metal fittings provided on the upper surface 621 of the bottom 62 of the floating dock 61, similar to the fixing member 65 (see Figure 9) described above.

[0071] The mooring line 41, which extends diagonally downward from the locking portion 25a of the first block 21 toward the bottom portion 62 of the floating dock 61, changes direction via a turning member 65a provided on the upper surface 621 of the bottom portion 62 (i.e., passing inside the turning member 65a), and extends diagonally upward toward one of the pair of side walls 63 of the floating dock 61. The end of the mooring line 41 opposite to the locking portion 25a is connected to a line length adjustment mechanism 24a provided on the one side wall 63.

[0072] Multiple locking portions 25a are provided on the first block 21, and each of the multiple mooring lines 41 extending downward from each of the multiple locking portions 25a extends upward toward one side wall portion 63 via the upper surface 621 of the bottom portion 62 of the floating dock 61 and is connected to one line length adjustment mechanism 24a, as described above. By adjusting the length of each of the multiple mooring lines 41, the relative position of the first block 21, which is anchored to the bottom portion 62 of the floating dock 61, with respect to the floating dock 61 is adjusted, in substantially the same manner as in the first manufacturing method (steps S14 to S15).

[0073] The length of each mooring line 41 is adjusted, for example, by a worker operating the line length adjustment mechanism 24a based on the position and orientation of the first block 21 obtained by visual inspection by the worker or supervisor. The same applies to the anchoring and position adjustment of the second block 22 and the third block 23 (see Figure 2). As a result, the first block 21, the second block 22, and the third block 23 are anchored to the bottom 62 of the floating dock 61 with their relative positions to each other and relative positions to the floating dock 61 adjusted with high precision. Then, the first block 21 and the second block 22, and the first block 21 and the third block 23 are temporarily joined in the same manner as described above.

[0074] In the second manufacturing method, the length of the mooring line 41 refers to the length of the portion of the mooring line 41 between the locking portion 25a and the turning member 65a of the floating dock 61. Alternatively, the length of the mooring line 41 in the second manufacturing method may refer to the length of the portion of the mooring line 41 that extends from the locking portion 25a through the turning member 65a to the line length adjustment mechanism 24a.

[0075] In the second manufacturing method, the lengths of the multiple mooring lines 41 are adjusted by the multiple line length adjustment mechanisms 24a from the start of the floating dock 61's ascent in step S16 until the first block 21, second block 22, and third block 23 settle on the bottom. This suppresses or prevents slack in the multiple mooring lines 41, and adjusts the relative positions of the first block 21, second block 22, and third block 23 with respect to the floating dock 61 in a plan view so that they are maintained at predetermined positions.

[0076] In the second manufacturing method, the adjustment of the length of the mooring line 41 by the line length adjustment mechanism 24a in steps S15 to S16 is not limited to the above example and may be performed by various other methods. For example, a position measuring unit 26a for measuring the relative position of the first block 21 with respect to the floating dock 61 (e.g., position and orientation in a plan view, vertical distance to the bottom 62, etc.) may be provided on the side wall 63 of the floating dock 61, and a plurality of line length adjustment mechanisms 24a may be automatically controlled based on the output from the position measuring unit 26a. As a result, the lengths of the plurality of mooring lines 41 connecting the plurality of line length adjustment mechanisms 24a and the first block 21 are automatically adjusted, and the relative position of the first block 21 with respect to the floating dock 61 is adjusted to a predetermined position. The same applies to the second block 22 and the third block 23.

[0077] The position measuring unit 26a includes, for example, a plurality of laser rangefinders and a computer that calculates the relative positions of the first block 21, the second block 22, and the third block 23 with respect to the floating dock 61 from the outputs of the plurality of laser rangefinders. The plurality of laser rangefinders may be provided on the floating dock 61 as described above, or on the first block 21, the second block 22, and the third block 23. In other words, the position measuring unit 26a is provided on the floating dock 61, or on the first block 21, the second block 22, and the third block 23.

[0078] As described above, in the second manufacturing method, each of the multiple mooring lines 41 extends from the first block 21, through the upper surface 621 of the bottom 62 of the floating dock 61, toward one of the pair of side walls 63 of the floating dock 61. Each of the multiple mooring lines 41 is connected to one of the multiple line length adjustment mechanisms 24a provided on the pair of side walls 63. The length adjustment of the multiple mooring lines 41 in step S15 is performed using the multiple line length adjustment mechanisms 24a.

[0079] This allows for easy position adjustment of the first block 21. Furthermore, unlike the first manufacturing method, there is no need to temporarily install and remove the line length adjustment mechanism 24a on the first block 21, thus eliminating the work required for such installation and removal. In addition, when adjusting the length of the mooring line 41, there is no need to position personnel on the first block 21 for the purpose of length adjustment, thus improving work safety. The same applies to the second block 22 and the third block 23.

[0080] As described above, in the second manufacturing method, a position measuring unit 26a for measuring the relative position of the first block 21 with respect to the floating dock 61 is provided on the floating dock 61 or the first block 21, and in step S15, it is preferable that the multiple line length adjustment mechanisms 24a are automatically controlled based on the output from the position measuring unit 26a. This allows for automatic position adjustment of the first block 21. Furthermore, the position adjustment of the first block 21 can be performed quickly and accurately. The same applies to the second block 22 and the third block 23.

[0081] Various modifications are possible to the manufacturing method of the floating structure 1 described above.

[0082] The first block 21, second block 22, and third block 23, which are aligned in step S15, do not necessarily need to be temporarily joined together. They may be joined together after they have settled on the bottom 62 of the floating dock 61 in an unjoined state.

[0083] In steps S14 to S16, it is not necessarily required that anchoring and mooring line length adjustment be performed for each of the first block 21, second block 22, and third block 23. For example, anchoring and mooring line length adjustment may be performed only for the first block 21, and not for the second block 22 and third block 23.

[0084] In step S11, the first block 21, the second block 22, and the third block 23 do not necessarily have to be manufactured in the small dock 71, but may be manufactured in various locations (for example, a large dry dock or a land yard).

[0085] The work performed in step S18 is not necessarily limited to joining the first block 21, the second block 22, and the third block 23, but may involve various tasks related to the manufacture of the floating structure 1.

[0086] In the first method for manufacturing the floating structure 1, the acquisition of the position and orientation of the first block 21 in step S15 does not necessarily have to be done by visual inspection by a worker or supervisor, but may be done, for example, by the position measuring unit 26a (see Figure 12) described above. The same applies to the second block 22 and the third block 23.

[0087] The shape and structure of the floating structure 1 are not limited to those illustrated in Figure 1 and may be modified in various ways. For example, the column 11 may be provided only in the center of the lower hull 12. Alternatively, the column 11 may be provided only at the radially outer ends of each hull section 121. In this case, the wind turbine for power generation is erected on the upper end of one of the columns 11. Furthermore, the floating structure 1 may be a semi-submersible floating structure without a lower hull. The floating structure 1 may also be a floating structure of a type other than semi-submersible (for example, a barge type, TLP type, spar type, etc.).

[0088] The floating structure 1 may be used for purposes other than offshore wind power generation systems.

[0089] The configurations in the above embodiments and each modified example may be combined as appropriate, as long as they do not contradict each other. [Explanation of Symbols]

[0090] 1. Floating structure 21 Block 1 22 Block 2 23 Block 3 24,24a Line length adjustment mechanism 26a Position measurement section 41 Mooring Line 61 Floating Dock 62 Bottom (of the floating dock) 63 Side wall section 65 Fixing member 71 Small Dock 91 sea level 621 Top surface (of the bottom of the floating dock) S11~S18 Step

Claims

1. A method for manufacturing a floating structure, a) A step of floating a floating dock having a bottom and a pair of side walls on the water with the upper surface of the bottom submerged in water, b) A step, performed after step a), of transporting the first block, which is part of the floating structure, by water to position the first block, floating on the water surface, vertically above the bottom of the floating dock, c) A step, performed after step a), in which the first block, while floating on the water surface, is anchored to the floating dock by a plurality of mooring lines extending from the first block toward the upper surface of the bottom of the floating dock, d) After steps b) and c), the step of adjusting the relative position of the first block with respect to the floating dock while it is floating on the water surface by adjusting the lengths of the plurality of mooring lines, thereby raising the floating dock and causing the first block to settle on the bottom of the floating dock, e) A step of supporting the first block above the water surface by further raising the floating dock after step d) so that it is aligned with the second block, which is another part of the floating structure, on the bottom of the floating dock, A method for manufacturing a floating structure equipped with [a specific feature / feature].

2. A method for manufacturing a floating structure according to claim 1, A method for manufacturing a floating structure, wherein the number of the aforementioned mooring lines is four or more.

3. A method for manufacturing a floating structure according to claim 1, A method for manufacturing a floating structure, wherein a plurality of fixing members are provided on the upper surface of the bottom of the floating dock, to which the ends of the plurality of mooring lines are each fixed.

4. A method for manufacturing a floating structure according to claim 1, A method for manufacturing a floating structure, wherein the length adjustment of each of the plurality of mooring lines in step d) is performed using a line length adjustment mechanism located on the first block.

5. A method for manufacturing a floating structure according to claim 1, Each of the aforementioned mooring lines extends from the first block, through the upper surface of the bottom of the floating dock, toward one of the pair of side walls of the floating dock, and is connected to one of the line length adjustment mechanisms provided on the pair of side walls. A method for manufacturing a floating structure, wherein the length adjustment of the plurality of mooring lines in step d) is performed using the plurality of line length adjustment mechanisms.

6. A method for manufacturing a floating structure according to claim 5, A position measuring unit for measuring the relative position of the first block with respect to the floating dock is provided on the floating dock or the first block. A method for manufacturing a floating structure, wherein in step d) above, the plurality of line length adjustment mechanisms are automatically controlled based on the output from the position measuring unit.

7. A method for manufacturing a floating structure according to any one of claims 1 to 6, Between step a) and step d), the second block is transported by water and positioned vertically above the bottom of the floating dock while floating on the water surface, and the second block is anchored to the floating dock by a plurality of mooring lines extending from the second block toward the upper surface of the bottom of the floating dock. A method for manufacturing a floating structure, wherein in step d) above, the relative position of the second block with respect to the floating dock is adjusted by adjusting the lengths of the plurality of mooring lines extending from the second block, and the second block is then set alighted on the bottom of the floating dock.

8. A method for manufacturing a floating structure according to claim 7, The first block and the second block are each manufactured in a small dock having a width less than the buildable width which is the width that allows the floating structure to enter and exit the dock. A method for manufacturing a floating structure, wherein the width between the pair of side walls of the floating dock is greater than or equal to the buildable width.

9. A method for manufacturing a floating structure according to any one of claims 1 to 6, The floating structure is a floating structure that supports a wind turbine for power generation in a floating offshore wind power generation system.

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