JP2024175430A - Manufacturing method of floating structure - Google Patents

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

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

In recent years, floating offshore wind power generation facilities have been put to practical use, and there is a demand for increased power generation capacity. For example, in an offshore wind power generation facility with a power generation capacity of 10 MW or more, the floating structure on which the wind turbines are mounted becomes very large. For this reason, such floating structures cannot be docked in and out of ordinary marine dry docks, even docks for building cargo ships such as ultra-large crude oil carriers (ULCCs) and ultra-large container ships, and must be built in large docks for building marine structures.

For example, Patent Document 1 proposes a method for manufacturing a large floating structure by transporting multiple blocks manufactured in a small dock to a large dock and assembling the multiple blocks in the large dock. This manufacturing method makes it possible to shorten the construction period at the large dock. However, since there are only a few large docks for building such marine structures, there are limitations to mass-producing the above-mentioned large floating structures. Furthermore, building a new large dock requires a vast site and a huge amount of money.

On the other hand, Patent Document 2 discloses a technology in which a caisson is manufactured on a floating dock that floats on the sea, and then the floating dock is lowered to launch the caisson.

JP 2022-74879 A Japanese Unexamined Patent Publication No. 7-149286

When manufacturing a large floating structure such as the above on a floating dock, one possible method is to manufacture the floating structure into multiple blocks in a relatively small dry dock and then assemble the multiple blocks on the floating dock. In this manufacturing method, the multiple blocks manufactured in the dry dock are towed on the ocean to above the floating dock, which is in a submerged state. The floating dock is then raised, and each block is supported by a platform installed on the bottom of the floating dock and lifted above the sea level. The multiple blocks are then joined together to form the large floating structure.

In the above manufacturing method, it is necessary to align the multiple blocks above the floating dock while it is submerged. In addition, the relative positions of the multiple blocks must be maintained when the floating dock is raised. However, unlike inside a dry dock where the gates are closed, the multiple blocks floating above the floating dock are prone to displacement due to external forces such as waves and currents, so there is a risk that the relative positions of the multiple blocks may become misaligned.

The present invention has been developed in consideration of the above-mentioned problems, and aims to precisely align multiple blocks on a floating dock.

Aspect 1 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 with the upper surface of the bottom submerged in water; b) transporting a first block, which is a part of the floating structure, on the water and positioning it vertically above the bottom of the floating dock while floating on the water surface; and c) anchoring the first block to the floating dock by a plurality of mooring lines each extending from the first block to the upper surface of the bottom of the floating dock. d) adjusting the length of each of the mooring lines to adjust the relative position of the first block to the floating dock, while floating the floating dock and causing the first block to land on the bottom of the floating dock; and e) supporting the first block above the water surface by further floating the floating dock, in a state where the first block is aligned with a second block, which is another part of the floating structure, on the bottom of the floating dock.

Aspect 2 of the present invention is a method for manufacturing a floating structure according to aspect 1, in which the number of the multiple mooring lines is four or more.

Aspect 3 of the present invention is a method for manufacturing a floating structure according to aspect 1 (or aspect 1 or 2), in which a plurality of fixing members to which the ends of the plurality of mooring lines are respectively fixed are provided on the upper surface of the bottom of the floating dock.

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), in which the length adjustment of each of the multiple mooring lines in step d) is performed using a line length adjustment mechanism arranged on the first block.

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

Aspect 6 of the present invention is a method for manufacturing a floating structure according to aspect 5, in which 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 multiple line length adjustment mechanisms are automatically controlled based on the output from the position measuring unit.

Aspect 7 of the present invention is a method for manufacturing a floating structure according to any one of aspects 1 to 6, in which, between steps a) and d), the second block is transported over 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 each extending from the second block toward the upper surface of the bottom of the floating dock. In step d), the second block is landed on the bottom of the floating dock while adjusting the relative position of the second block to the floating dock by adjusting the lengths of the plurality of mooring lines each extending from the second block.

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

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), in which the floating structure is a float supporting a power-generating wind turbine in a floating offshore wind power generation system.

The present invention allows for precise alignment of multiple blocks on a floating dock.

FIG. FIG. 2 is a plan view of a first block, a second block, and a third block. FIG. FIG. 1 is a diagram showing the manufacturing flow of a floating structure. FIG. 2 is a plan view showing a first block, a second block, and a third block in the mini-dock. FIG. 2 is a front view of the floating dock. FIG. 2 is a plan view of the floating dock. FIG. 2 is a plan view of the floating dock, and the first block, the second block, and the third block. FIG. 2 is a front view of the floating dock, and the first block, the second block, and the third block. FIG. 2 is a front view of the floating dock, and the first block, the second block, and the third block. FIG. 2 is a front view of the floating dock, and the first block, the second block, and the third block. FIG. 2 is a front view of the floating dock and the first block.

First, a method for manufacturing a floating structure according to a first embodiment of the present invention (hereinafter, also referred to as the "first manufacturing method") will be described. The manufacturing method will be described below using a floating structure 1 shown in a perspective view in FIG. 1 as an example. The floating structure 1 is a large float that supports a power-generating wind turbine from below while floating on the water surface (i.e., the sea surface) in a floating offshore wind power generation system.

The floating structure 1 illustrated in FIG. 1 is a lower hull type semi-submersible float. The floating structure 1 includes 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 the one column 11. The three columns 11 have, for example, approximately the same shape. The central column 11 may have approximately the same shape as the three columns 11, or may have a different shape.

Each column 11 is a generally columnar member that extends upward from the lower hull 12 in a generally straight line generally parallel to the vertical direction and penetrates 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 FIG. 1, each column 11 is a generally cylindrical member. The shape of the column 11 may be modified in various ways, such as a rectangular column. The support pillar (also called a tower) of the above-mentioned power-generating wind turbine (not shown) is erected, for example, on the upper end of the central column 11.

The lower hull 12 is a member connected to the lower part of the four columns 11. Almost the entire lower hull 12 is placed underwater (i.e., under 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 protruding height of the columns 11 from the sea surface) and the attitude of the lower hull 12, etc. are adjusted.

In the example shown in FIG. 1, the lower hull 12 includes a hull center portion 122 and three hull portions 121. The three hull portions 121 extend radially and substantially horizontally from the lower end of the central column 11. The three hull portions 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") about the central axis of the central column 11. Each hull portion 121 is a substantially columnar portion that extends substantially linearly and substantially parallel to the radial direction (hereinafter also simply referred to as the "radial direction") about the central axis of the central column 11.

In the example shown in FIG. 1, each hull portion 121 is a substantially rectangular prism-shaped portion. The shape of a cross section perpendicular to the longitudinal direction (i.e., radial direction) of each hull portion 121 is substantially rectangular, and is, for example, substantially the same over the entire longitudinal length. The shape of each hull portion 121 may be modified in various ways, such as to be cylindrical. The hull central portion 122 is connected to the lower end of the central column 11, and connects the radially inner ends of the three hull portions 121. The three columns 11 other than the central column 11 are connected to the radially outer ends (i.e., the tips) of the three hull portions 121.

In the example shown in FIG. 1, the floating structure 1 has a vertical height (hereinafter simply referred to as "height") of about 30 m to 40 m. The lower hull 12 has a height of about 5 m to 10 m, and each column 11 has a height of about 25 m to 30 m. The column 11 has a diameter of about 10 m to 20 m. The power-generating wind turbine attached to the central column 11 has a power generation capacity of, for example, 15 MW. The width of the hull portion 121 of the lower hull 12 in the width direction (i.e., the direction perpendicular to the upstream direction and the longitudinal direction) is about 12 m to 20 m, and the longitudinal length (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 about 40 m to 60 m. The size and shape of the floating structure 1 may be changed in various ways.

In FIG. 1, if the longitudinal and width directions of one hull section 121 extending to the right from the central column 11 are respectively defined as the longitudinal and width directions of the floating structure 1, 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 the column 11) is approximately 100 m. The length, width and height of each part of the floating structure 1 may be changed in various ways.

When the floating structure 1 is manufactured, roughly speaking, multiple blocks that will become part of the floating structure 1 are manufactured in a small dry dock, and the multiple blocks are transported on water (i.e., transported by sea) and brought into one floating dock. Then, in the floating dock, the multiple blocks are joined (i.e., assembled) to manufacture the floating structure 1. This allows the floating structure 1 to be manufactured efficiently, without the need to prepare an extra-large dry dock or a vast onshore yard.

In a specific example of the manufacturing method described below, as shown in FIG. 2 (plan view), the floating structure 1 is manufactured in a divided state into three blocks 21-23. Then, as shown in FIG. 3 (plan view), the three blocks 21-23 are joined together to form the floating structure 1. Block 21 comprises a hull center portion 122, one hull portion 121, and two columns 11 connected to the radial outer ends of the hull center portion 122 and the hull portion 121, respectively. Each of blocks 22 and 23 comprises one hull portion 121 and one column 11 connected to the radial outer end of the hull portion 121. In the following description, for convenience, blocks 21-23 will be referred to as the "first block 21," the "second block 22," and the "third block 23," respectively.

The division mode of the floating structure 1 is not limited to the example shown in FIG. 2 and may be modified in various ways. For example, the joint between the first block 21 and the second block 22 does not need to be provided at the boundary between the hull center portion 122 and the hull portion 121, but may be provided at the center of the hull portion 121 in the longitudinal direction, etc. The same applies to the joint between the first block 21 and the third block 23. The hull center portion 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, but may be two or four or more.

The small dock described above is a dry dock for building cargo ships such as crude oil tankers and container ships, and is, for example, a normal marine dock with a width (i.e., gate width) of 75 m or less. The small dock is, for example, a dry dock or a slipway. The floating dock has a width larger than the floating structure 1 (for example, more than 75 m). As described above, the width of the floating structure 1 illustrated in FIG. 1 is about 100 m, so the floating structure 1 cannot be docked in or out of the small dock. In addition, since the length of the floating structure 1 is also about 100 m, the floating structure 1 cannot be docked in or out of the small dock even if the orientation of the floating structure 1 is changed.

Next, the flow of the manufacturing method of the floating structure 1 will be specifically described with reference to FIG. 4 and the like. When the floating structure 1 is manufactured, first, as shown in FIG. 5 (plan view), the first block 21, the second block 22, and the third block 23, each of which is a part of the floating structure 1, are manufactured in the small dock 71 with the gate 711 closed and drained (i.e., dry) (step S11). In FIG. 5, to facilitate understanding of the figure, the water (i.e., seawater) present outside the gate 711 of the small dock 71 is shaded. As described above, the small dock 71 has a width less than the width at which the floating structure 1 can be docked (hereinafter also referred to as the "buildable width"). The width of the small dock 71 is, for example, 75 m or less. In the example shown in FIG. 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.

When the manufacture of the first block 21, the second block 22, and the third block 23 is completed, water is poured into the small dock 71, and the first block 21, the second block 22, and the third block 23 float up. The first block 21, the second block 22, and the third block 23 are sequentially docked from the small dock 71 through the opened gate 711 using a tugboat or the like. A floating dock is positioned on the sea in advance (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 sea surface.

The marine transportation of the first block 21, the second block 22, and the third block 23 is not limited to towing while floating on the sea surface, but may be performed by various other methods. For example, the first block 21 may be loaded onto a self-propelled barge and transported at sea, or loaded onto a non-self-propelled barge and towed by a tugboat. The same applies to the second block 22 and the third block 23.

6 is a front view showing the floating dock 61. FIG. 7 is a plan view showing the floating dock 61. The floating dock 61 includes a bottom 62 and a pair of side walls 63. The bottom 62 is a substantially rectangular parallelepiped portion extending substantially perpendicular to the up-down direction. The shape of the bottom 62 in plan view is, for example, substantially rectangular. The pair of side walls 63 are erected upward from the bottom 62 and are substantially rectangular parallelepiped portions extending substantially perpendicular to the left-right direction in FIG. 6 (hereinafter also simply referred to as the "left-right direction"). The shape of each side wall 63 in side view is, for example, substantially rectangular. The shape of the pair of side walls 63 is, for example, substantially the same. The pair of side walls 63 are provided on the bottom 62 along both side edges of the bottom 62 in the left-right direction. As shown in FIG. 6, the bottom 62 and the pair of side walls 63 have a generally rectangular shape when viewed from the front, and the bottom 62 and the pair of side walls 63 extend in a direction perpendicular to the paper surface in FIG. 6 (hereinafter also referred to as the "front-rear direction").

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

In the state shown in FIG. 6, the floating dock 61 floats on the sea surface without touching the bottom of the water (i.e., the seabed) with the upper surface 621 of the bottom 62 submerged in the sea (i.e., located below the sea surface 91). This state is achieved by pouring water into a ballast tank (not shown) provided inside the floating dock 61. The pair of side wall portions 63 penetrate the sea surface 91. In other words, the upper portions of the pair of side wall portions 63 are located above the sea surface 91. The floating dock 61 may also be grounded on the seabed.

A number of platforms (also called blocks) 64 are fixed at predetermined positions on the upper surface 621 of the bottom 62 of the floating dock 61. As described below, each of the platforms 64 is a block support that contacts and supports the first block 21, the second block 22, or the third block 23 from below. The arrangement of the platforms 64 may be changed as appropriate.

In addition, a plurality of fixing members 65 to which the ends of the plurality of mooring lines 41 are respectively fixed are provided on the upper surface 621 of the bottom 62 of the floating dock 61. Note that the mooring lines 41 are not shown in FIG. 7. The fixing members 65 and the mooring lines 41 are members 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 in which movement is restricted, as described later. The fixing members 65 are, for example, approximately semicircular, retractable metal fittings provided on the upper surface 621 of the bottom 62 of the floating dock 61. One end (hereinafter also referred to as the "lower end") of one or more mooring lines 41 is connected to each fixing member 65.

The mooring line 41 is a generally 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 synthetic fiber or metal rope containing wire. In the following description, the mooring line 41 is assumed to be a metal rope.

The other end of each mooring line (i.e., the end opposite to the end connected to the fixed member 65, hereinafter also referred to as the "upper end") is connected to a small buoy 42 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.

The first block 21, the second block 22, and the third block 23 that have been towed to the floating dock 61 are placed 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 a predetermined position in a plan view (step S13).

Next, as shown in FIG. 8 (plan view) and FIG. 9 (front view), workers (not shown) positioned on the first block 21, the second block 22, and the third block 23 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, respectively. Specifically, the workers pull in the small buoy 42 (see FIG. 6) with a hand hook or the like to retrieve the upper ends of the mooring lines 41, and connect the upper ends to the line length adjustment mechanisms 24.

The line length adjustment mechanism 24 is, for example, a tensioner such as a chain block. The line length adjustment mechanism 24 is, for example, temporarily installed on the upper surface of each of the hull portions 121 of the first block 21, the second block 22, and the third block 23 so that it can be removed. Note that a mechanism other than a tensioner may be used as the line length adjustment mechanism 24. Furthermore, the line length adjustment mechanism 24 may be left on the first block 21, the second block 22, and the third block 23 even after the manufacture of the floating structure 1 is completed.

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 that extend in different directions from the first block 21 to the upper surface 621 of the bottom 62 of the floating dock 61. The second block 22 is anchored to the bottom 62 of the floating dock 61 by a plurality of mooring lines 41 that extend in different directions from the second block 22 to 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 that extend in different directions from the third block 23 to the upper surface 621 of the bottom 62 of the floating dock 61 (step S14).

In the example shown in FIG. 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 FIG. 8 is connected to the same fixed member 65 as the single mooring line 41 extending from the second block 22. The mooring line 41 extending from the upper left end of the first block 21 in FIG. 8 is connected to the same fixed member 65 as the single mooring line 41 extending from the third block 23.

The number of mooring lines 41 used for anchoring may be the same or different for the first block 21, the second block 22, and the third block 23. The number of mooring lines 41 used for anchoring the first block 21 may be two, but is 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 platforms 64 provided on the upper surface 621 of the bottom 62).

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, and then the first block 21, the second block 22, and the third block 23 are anchored, but this is not limited to the above. For example, after the first block 21 is positioned above the floating dock 61 (step S13), the second block 22 may be positioned above the floating dock 61 and anchored in parallel with the anchoring of the first block 21 (step S14), or after the anchoring of the first block 21 (step S14). The same applies to the third block 23. That is, the second block 22 and the third block 23 may be positioned above the floating dock 61 and anchored between the above-mentioned step S12 and step S15 described later.

When step S14 is completed, the multiple line length adjustment mechanisms 24 on the first block 21 are each operated by an operator 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 a plan view so as to approach the fixed member 65 to which the lower end of that one mooring line 41 is connected, or rotated in a plan view so as to face the fixed member 65.

The length of each mooring line 41 is adjusted based on the position and orientation of the first block 21, for example, 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 to the floating dock 61 to a predetermined position (step S15). Note that 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.

In step S15, the line length adjustment mechanisms 24 on the second block 22 are operated by an operator to adjust the length of each of the multiple mooring lines 41 (four in the above example) connected to the second block 22. This adjusts the position of the second block 22 in a plan view, and adjusts the relative position of the second block 22 to the floating dock 61 to a predetermined position. The relative position of the second block 22 to the first block 21 is also adjusted so that they can be joined.

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

That is, 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. The relative positions of the first block 21 and the second block 22 after alignment, and the first block 21 and the third block 23 after alignment, are maintained by temporarily joining them using, for example, a construction piece or the like (not shown). Note that in Figures 8 and 9, the gaps between the first block 21 and the second block 22, and between the first block 21 and the third block 23 are depicted as being larger than they actually are (the same applies to Figures 10 and 11 described below).

Next, the ballast tank of the floating dock 61 is drained, and the floating dock 61 rises from the state shown in FIG. 9. This causes the floating dock 61 to move upward relative to the first block 21, the second block 22, and the third block 23. Then, as shown in FIG. 10 (front view), a plurality of platforms 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 plurality of platforms 64. That is, the first block 21, the second block 22, and the third block 23 land on the bottom 62 of the floating dock 61 (step S16).

In step S16, from the start of floating dock 61 rising to the bottom of first block 21, second block 22, and third block 23, the line length adjustment mechanisms 24 on first block 21, second block 22, and third block 23 are operated by an operator to adjust the length of each of the mooring lines 41 extending from first block 21, second block 22, and third block 23. Specifically, the length of each mooring line 41 is shortened as floating dock 61 rises. This suppresses or prevents slack in the mooring lines 41, and adjusts the relative positions of first block 21, second block 22, and third block 23 to floating dock 61 in a plan view, and the relative positions of first block 21, second block 22, and third block 23 to each other in a plan view, so as to be maintained in predetermined positions.

The floating dock 61 continues to float even after the first block 21, the second block 22, and the third block 23 come into contact with the multiple racks 64, and is stopped when the upper surface 621 of the bottom 62 of the floating dock 61 is positioned above the sea level 91, as shown in FIG. 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 above the upper surface 621 of the bottom 62. As a result, the top of the bottom 62 of the floating dock 61 becomes dry, and the first block 21, the second block 22, and the third block 23 are supported above the sea level 91 (step S17).

Then, the first block 21, the second block 22, and the third block 23 are disconnected from the bottom 62 of the floating dock 61 by the multiple mooring lines 41, and the multiple line length adjustment mechanisms 24 are removed from the first block 21, the second block 22, and the third block 23. After that, the first block 21, the second block 22, and the third block 23 are joined (i.e., main joining) and painted 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 performed in parallel with step S18.

As described above, the manufacturing method of the floating structure 1 includes a step of floating the floating dock 61, which has a bottom 62 and a pair of side walls 63, on the water with the upper surface 621 of the bottom 62 submerged (step S12), a step of transporting the first block 21, which is a 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 a step of anchoring the first block 21 to the floating dock 61 by a plurality of mooring lines 41 each extending from the first block 21 to the upper surface 621 of the bottom 62 of the floating dock 61. The method includes a step of adjusting the length of each of the mooring lines 41 to adjust the relative position of the first block 21 to the floating dock 61 (step S14), a step of floating the floating dock 61 to land the first block 21 on the bottom 62 of the floating dock 61 (step S16), and a step of supporting the first block 21 above the water surface 91 by further floating the floating dock 61 in a state where the first block 21 is aligned 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).

In this manufacturing method, the first block 21 is anchored to the bottom 62 of the floating dock 61 and its position is adjusted, so that 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 subject to the influence of waves, tides, etc. This allows for accurate alignment of multiple blocks on the floating dock 61 (e.g., alignment of the first block 21 and the second block 22). As a result, adjustment of the relative positions between the blocks can be omitted or suppressed after the multiple blocks have landed on the bottom. This makes it easier to join the multiple blocks, and facilitates the manufacturing of the floating structure 1.

Preferably, the number of the above-mentioned mooring lines 41 (i.e., the 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 the position of the first block 21 to be adjusted easily and accurately by adjusting the length of the mooring lines 41. The same applies to the second block 22 and the third block 23.

As described above, it is preferable that the upper surface 621 of the bottom 62 of the floating dock 61 be 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 respectively fixed. This simplifies the structure relating to the anchoring of the first block 21. The same applies to the second block 22 and the third block 23.

The length adjustment of each of the multiple mooring lines 41 in step S16 is preferably performed using a line length adjustment mechanism 24 arranged 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. In addition, the line length adjustment mechanism 24 can be easily arranged in an appropriate position (e.g., a position where the multiple mooring lines 41 do not cross each other) according to the shape of the first block 21 and the arrangement of the fixing members 65 on the bottom 62 of the floating dock 61. The same applies to the second block 22 and the third block 23.

In the above-mentioned method for manufacturing the floating structure 1, between steps S12 and S15, it is preferable that the second block 22 is transported over water 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 each extending from the second block 22 toward the upper surface 621 of the bottom 62 of the floating dock 61. In addition, in step S15, it is preferable that the second block 22 is landed on the bottom 62 of the floating dock 61 while adjusting the relative position of the second block 22 to the floating dock 61 by adjusting the lengths of the plurality of mooring lines 41 each extending from the second block 22.

This allows the relative position of the second block 22 to the floating dock 61 and the first block 21 to be adjusted with high precision even on the floating dock 61, which is subject to the influence of waves, tides, etc. 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.

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 leave the dock. In addition, the width between the pair of side walls 63 of the floating dock 61 is equal to or greater than the buildable width. This allows the floating structure 1 to be manufactured efficiently without preparing 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 installation waters of the floating structure 1. As a result, it is possible to reduce the cost and time required to transport the floating structure 1 to the installation waters. It is also preferable that the third block 23 is manufactured in the small dock 71 described above.

The floating structure 1 is preferably a float that supports a power-generating 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 an extra-large dry dock or a vast onshore yard. In contrast, according to the manufacturing method of the floating structure 1 described above, an extra-large dry dock or a vast onshore yard is not required, and therefore the manufacturing method is particularly suitable for manufacturing a float that supports the above-mentioned power-generating wind turbine.

Next, a method for manufacturing a 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 a floating structure 1 is substantially the same as the above-mentioned first manufacturing method (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 FIG. 4) is different.

Figure 12 is a front view showing a part of a floating structure 1 in the process of being manufactured by the second manufacturing method. In Figure 12, the first block 21, which is spaced above the bottom 62 of the floating dock 61 and floats on the sea surface 91, is anchored to the bottom 62 of the floating dock 61 by a method different from that of the first manufacturing method described above (see Figure 9). Note that the second block 22 and the third block 23 are not shown in Figure 12, but the second block 22 and the third block 23 are also anchored to the bottom 62 of the floating dock 61 in a manner substantially similar to that of the first block 21. Also, in Figure 12, the configuration related to the anchoring and bottoming of the second block 22 and the third block 23 is not shown in order to make the figure easier to understand.

In the second manufacturing method, a plurality of line length adjustment mechanisms 24a are provided on each side wall 63 of the floating dock 61. In FIG. 12, the line length adjustment mechanism 24a shown in FIG. 12 is, for example, an electric or hydraulic winch. Each line length adjustment mechanism 24a is disposed, for example, above the sea surface 91. In the example shown in FIG. 12, the line length adjustment mechanism 24 (see FIG. 9) such as the above-mentioned load tensioner is not provided on the first block 21, and a locking portion 25a such as a bollard to which the end (i.e., the upper end) of the mooring line 41 is locked is provided.

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, roughly semicircular, tiltable fittings provided on the upper surface 621 of the bottom 62 of the floating dock 61, similar to the fixing members 65 (see FIG. 9) described above.

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

A number of locking portions 25a are provided on the first block 21, and a number of mooring lines 41 extending downward from each of the plurality of locking portions 25a each extend upward toward one side wall portion 63 via the upper surface 621 of the bottom portion 62 of the floating dock 61, as described above, and are connected to one line length adjustment mechanism 24a. Then, by adjusting the length of each of the plurality of mooring lines 41, the relative position of the first block 21 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).

The length of each mooring line 41 is adjusted by, for example, 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 a 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 to the floating dock 61 precisely adjusted. 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 above.

The length of the mooring line 41 in the second manufacturing method means 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. Note that the length of the mooring line 41 in the second manufacturing method may be the length of the portion of the mooring line 41 from the locking portion 25a through the turning member 65a to the line length adjustment mechanism 24a.

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 time the floating dock 61 starts to float in step S16 until the first block 21, the second block 22, and the third block 23 hit the bottom. This suppresses or prevents slack in the multiple mooring lines 41, and adjusts the relative positions of the first block 21, the second block 22, and the third block 23 to the floating dock 61 in a plan view so that they are maintained at predetermined positions.

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 measurement unit 26a that measures the relative position of the first block 21 to the floating dock 61 (e.g., the position and orientation in a plan view, the vertical distance to the bottom 62, etc.) may be provided on the side wall 63 of the floating dock 61, and the multiple line length adjustment mechanisms 24a may be automatically controlled based on the output from the position measurement unit 26a. As a result, the lengths of the multiple mooring lines 41 connecting the multiple line length adjustment mechanisms 24a and the first block 21 are automatically adjusted, and the relative position of the first block 21 to the floating dock 61 is adjusted to a predetermined position. The same applies to the second block 22 and the third block 23.

The position measurement unit 26a includes, for example, a plurality of laser range finders 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 output of the plurality of laser range finders. As described above, the plurality of laser range finders may be provided in the floating dock 61, or may be provided in the first block 21, the second block 22, and the third block 23. That is, the position measurement unit 26a is provided in the floating dock 61, or in the first block 21, the second block 22, and the third block 23.

As described above, in the second manufacturing method, each of the multiple mooring lines 41 extends from the first block 21 via 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. Also, 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. Then, the length adjustment of the multiple mooring lines 41 in step S15 is performed using the multiple line length adjustment mechanisms 24a.

This allows the position of the first block 21 to be easily adjusted. Also, 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, so the work required for such temporary installation and removal can be omitted. Furthermore, when adjusting the length of the mooring line 41, there is no need to position personnel for the length adjustment on the first block 21, so work safety can be improved. The same applies to the second block 22 and the third block 23.

As described above, in the second manufacturing method, a position measurement unit 26a that measures the relative position of the first block 21 with respect to the floating dock 61 is provided in 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 measurement unit 26a. This allows the position adjustment of the first block 21 to be performed automatically. In addition, the position adjustment of the first block 21 can also be performed quickly and accurately. The same applies to the second block 22 and the third block 23.

The manufacturing method for the floating structure 1 described above can be modified in various ways.

The first block 21, the second block 22 and the third block 23 aligned in step S15 do not necessarily need to be temporarily joined, and may be joined after landing on the bottom 62 of the floating dock 61 in an untemporarily joined state.

In steps S14 to S16, it is not necessary to perform anchoring and length adjustment of the mooring line 41 for each of the first block 21, the second block 22, and the third block 23. For example, anchoring and length adjustment of the mooring line 41 may be performed only for the first block 21, and not for the second block 22 and the third block 23.

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 (e.g., a large dry dock, an onshore yard, etc.).

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, and various work related to the manufacture of the floating structure 1 may be performed.

In the first manufacturing method of the floating structure 1, the position and orientation of the first block 21 in step S15 does not necessarily have to be acquired by visual inspection by a worker or a supervisor, but may be acquired, for example, by the above-mentioned position measurement unit 26a (see FIG. 12). The same applies to the second block 22 and the third block 23.

The shape and structure of the floating structure 1 are not limited to those illustrated in FIG. 1 and may be modified in various ways. For example, the column 11 may be provided only at the center of the lower hull 12. Alternatively, the column 11 may be provided only at the radially outer end of each hull portion 121. In this case, the power-generating wind turbine is erected on the upper end of one of the columns 11. The floating structure 1 may also be a semi-submersible floating structure that does not have a lower hull. The floating structure 1 may also be a floating structure of a type other than a semi-submersible type (for example, a barge type, a TLP type, a spar type, etc.).

The floating structure 1 may be used for purposes other than an offshore wind power generation system.

The configurations in the above embodiment and each modified example may be combined as appropriate as long as they are not mutually inconsistent.

Reference Signs List 1 Floating structure 21 First block 22 Second block 23 Third block 24, 24a Line length adjustment mechanism 26a Position measurement unit 41 Mooring line 61 Floating dock 62 Bottom (of floating dock) 63 Side wall 65 Fixing member 71 Small dock 91 Sea surface 621 Top surface (of bottom of floating dock) S11 to S18 Steps

Claims (9)

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 water with an upper surface of the bottom submerged in water;
b) a step of transporting a first block, which is a part of a floating structure, on water and positioning the first block vertically above the bottom of the floating dock while floating on the water surface;
c) anchoring the first block to the floating dock by a plurality of mooring lines each extending from the first block to the upper surface of the bottom of the floating dock;
d) adjusting the length of each of the mooring lines to adjust the relative position of the first block with respect to the floating dock, and floating the floating dock so that the first block is landed on the bottom of the floating dock;
e) supporting the first block above the water surface in a state where the first block is aligned with a second block, which is another part of the floating structure, on the bottom of the floating dock by further floating the floating dock;
A manufacturing method for a floating structure comprising the steps of: A method for manufacturing a floating structure according to claim 1,
A method for manufacturing a floating structure, wherein the number of the plurality of mooring lines is four or more. A method for manufacturing a floating structure according to claim 1,
A method for manufacturing a floating structure, comprising providing a plurality of fixing members to which ends of the plurality of mooring lines are respectively fixed on the upper surface of the bottom of the floating dock. 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 arranged on the first block. A method for manufacturing a floating structure according to claim 1,
Each of the 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 a plurality of 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. A method for manufacturing a floating structure according to claim 5,
a position measuring unit that measures a relative position of the first block with respect to the floating dock is provided in the floating dock or the first block;
A method for manufacturing a floating structure, wherein in the step d), the plurality of line length adjustment mechanisms are automatically controlled based on an output from the position measurement unit. A method for manufacturing a floating structure according to any one of claims 1 to 6,
Between the steps a) and d), the second block is transported on 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 each extending from the second block toward the upper surface of the bottom of the floating dock;
In step d), the second block is landed on 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 multiple mooring lines extending from the second block. 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 a buildable width that allows the floating structure to enter and leave the dock;
A method for manufacturing a floating structure, wherein the width between the pair of side wall portions of the floating dock is greater than or equal to the buildable width. A method for manufacturing a floating structure according to any one of claims 1 to 6,
The floating structure is a manufacturing method for a floating structure that is a float supporting a power-generating wind turbine in a floating offshore wind power generation system.

Images