Construction method for floating offshore wind power generation facility

Abstract

An on-water structure 10 is temporarily installed in a sea area having a water depth of 8 m or more and 20 m or less, a plurality of work areas A are provided in a sea area adjacent to the on-water structure 10, and a plurality of sets of assembly components of a wind power generation device 3 are temporarily placed on the on-water structure 10. A self-elevating barge 30B anchored in an arbitrary work area A is used to perform assembly work in which an assembly body 9 is assembled by installing a set of assembly components onto a floating body 2 fixed to a water bottom SB of the work area A. The self-elevating barge 30B is moved from the work area A, in which the assembly work is finished, to another work area A, performs the assembly work with respect to the floating body 2 fixed to the water bottom SB of the work area A, and, in parallel with the assembly work, performs additional work with respect to the assembly body 9 for which the assembly work was finished earlier. As a result, it is possible to efficiently construct a floating offshore wind power generation facility in which the draft of the floating body moored in the installation-target sea area is 20 m or less, without the need to install a mounting base for the floating offshore wind power generation facility on a quay.

Description

Construction method for floating offshore wind power generation facilities

[0001] The present invention relates to a construction method for a floating offshore wind power facility, and more specifically to a construction method for a floating offshore wind power facility that can efficiently construct a floating offshore wind power facility with a floater draft of 20 m or less when moored in the target sea area, without the need to prepare an installation base (base port) for the floating offshore wind power facility on a quay.

[0002] Floating offshore wind power generation facilities, which have a structure in which a wind power generation device is erected on a float moored in the sea area, are classified according to the structure of the float into spar-type, semi-submersible, TLP (tension leg platform)-type, and barge (concrete)-type. For example, as described in Japanese Patent Application Laid-Open No. 2012-202250 (hereinafter referred to as Patent Document 1), a spar-type floating offshore wind power generation facility has a column-shaped spar-type float approximately 50 m to 100 m in height, most of which is submerged, and a wind power generation device is erected on this single huge spar-type float. When moored in the target sea area, the draft of the spar-type float is approximately 50 m to 100 m. On the other hand, in floating offshore wind power generation facilities other than the spar type, such as semi-submersible, TLP, and barge types, the float is semi-submerged and floats on the sea, and the draft of the semi-submersible, TLP, and barge floats when moored in the target sea area for installation is 20 m or less. Specifically, for example, in a semi-submersible floating offshore wind power generation facility, a semi-submersible float having multiple columns with a height of about 20 m to 40 m and connectors (so-called footing members, etc.) that connect the columns is semi-submerged and floats on the sea, and a wind power generation device is erected on one of the columns of the float.

[0003] In a typical construction method for a spar-type floating offshore wind turbine, the spar-type float and the tower that constitute the wind turbine are connected in a tilted state on land such as a quay, and the combined spar-type float and tower are loaded onto a semi-submersible barge in this tilted state and transported to a sea area with a water depth of 100 meters or more. The combined spar-type float and tower is then launched in the sea area with a water depth of 100 meters or more, and the ballast water of the spar-type float is adjusted to raise the combined unit from its tilted state to an upright position. The upright combined unit is then towed to the target sea area for installation and moored in the target sea area with a water depth of 100 meters or more. Next, a fixed crane vessel is used to install a nacelle hub on top of the tower, and blades are installed on the nacelle hub, thereby completing the erection of the spar-type floating offshore wind turbine.

[0004] The invention described in Patent Document 1 differs from general construction methods in that a bent section is provided midway through the tower and the wind turbine (nacelle hub and blades) is installed on the tower on land, but even in the invention described in Patent Document 1, the spar-type floating body (foundation) and the wind turbine tower are assembled as a single unit on land.

[0005] The float and the wind turbine that constitute a floating offshore wind power generation facility are very large and heavy. Therefore, it is difficult to transport the float and the tower as a single unit over long distances on land. Therefore, when assembling the float and the tower assembly (unit) on land, as in the general construction method or the invention described in Patent Document 1, it is necessary to secure space on land, such as a quay, for loading the float and the wind turbine assembly components, and to secure space for assembling the assembly and launch the assembly directly into the sea. However, in many cases, the ground at a typical quay does not have the strength to withstand the load of the assembly. Therefore, establishing an installation base for a floating offshore wind power generation facility on a quay requires large-scale construction work, such as ground improvement work to improve the bearing capacity of the quay or apron, which requires relatively high costs, labor, and time. In particular, when assembling multiple assemblies on land, it may be difficult to secure a large space on a quay as an installation base for a floating offshore wind power generation facility.

[0006] Furthermore, in a typical construction method for a spar-type floating offshore wind power generation facility, work is required to erect the spar-type float and tower unit that has been laid on its side in waters with a depth of 100 meters or more. The construction method described in Patent Document 1 also requires the hinge opening / closing means to change the rear part of the tower hinge and the spar-type float (foundation) from their laid-down state to an upright state. Therefore, the construction methods proposed so far have the problem of requiring sophisticated and complicated work at sea. As such, the construction methods proposed so far have various problems and there is room for improvement.

[0007] Japanese Patent Application Publication No. 2012-202250

[0008] An object of the present invention is to provide a construction method for a floating offshore wind power generation facility that can efficiently construct a floating offshore wind power generation facility with a float draft of 20 m or less when moored in the target sea area, without the need to prepare an installation base for the floating offshore wind power generation facility on a quay.

[0009] In order to achieve the above object, the construction method of the present invention for floating offshore wind power generation facilities comprises a float moored in a target sea area for installation and a wind power generation device erected on the float, and the float has a draft of 20 m or less from the water surface to the bottom end of the float while being moored in the target sea area for installation. The construction method comprises constructing a temporary floating structure in a sea area with a water depth of 8 m to 20 m, setting up multiple work areas in the sea area adjacent to the floating structure, temporarily placing multiple sets of assembly parts of a nacelle hub, blades and tower that constitute the wind power generation device on the floating structure, and lifting a self-elevating barge having lifting legs, a barge body that can be lifted and lowered on the lifting legs, and a crane mounted on the barge body, and lifting the self-elevating barge to the bottom ground of any of the work areas. The self-elevating barge is stopped in a jacked-up state with its lifting legs touching the bottom, and a crane on the self-elevating barge is used to install a set of assembly parts that are temporarily placed on the water structure onto the floating body that has been touched down on the bottom of the work area, and assembly work is performed to assemble an assembly on the floating body on which the wind power generation device is constructed, and the self-elevating barge is moved sequentially from the work area where the assembly work has been completed to another work area, and the assembly work is performed on the floating body that has been touched down on the bottom of the water in that work area, and in parallel with this, additional work including adjustment work is performed on the assemblies that have already completed the assembly work, and the assemblies that have completed the additional work are sequentially transported by sea to the installation target sea area and moored in the installation target sea area.

[0010] The present invention is a method for constructing multiple floating offshore wind turbines in parallel, each with a floater draft of 20 m or less while moored in the target sea area. It can be used for constructing floating offshore wind turbines of other types (semisubmersible, TLP, and barge types) except for spar types. In this method, temporary floating structures are constructed in a relatively shallow sea area with a water depth of 8 m to 20 m, so the cost, labor, and time required for constructing the floating structures are relatively low. Since the assembly components of the wind turbine generator are temporarily placed on the floating structure, there is no need to prepare a floating offshore wind turbine installation base where assembly components are temporarily stored together on a quay. By constructing the floating structures in a sea area with a water depth of 8 m to 20 m, a self-elevating barge can be jacked up and moored near the floating structure, and the floating structure can be easily landed on the water bottom near the floating structure. By using a crane on a self-elevating barge that is not affected by waves and by having the float rest on the water bottom, the assembly work of installing a set of assembly parts on the float and assembling the assembly with the wind turbine power generation system on the float can be carried out in a very stable and efficient manner. Furthermore, multiple work areas are set up in the sea area adjacent to the floating structure, and the self-elevating barge that has completed assembly work in a given work area is moved sequentially from the completed work area to another work area, where the assembly work is carried out in that work area, while additional work, including adjustment work, is carried out on the assembly that has been completed earlier. This allows the assembly work and additional work to be carried out in parallel in separate locations, allowing the self-elevating barge to be used efficiently. The assembly that has completed the additional work is then transported by sea to the target sea area, where the construction of the floating offshore wind power generation facility is completed simply by mooring the assembly. Therefore, with the present invention, multiple floating offshore wind power generation facilities (other types of floating offshore wind power generation facilities excluding spar types) with a float draft of 20 m or less when moored in the target sea area can be efficiently constructed in parallel without the need to prepare an installation base for the floating offshore wind power generation facilities on a quay.

[0011] FIG. 1 is an explanatory diagram illustrating a front view of a semi-submersible floating offshore wind power generation facility constructed according to the present invention. FIG. 2 is an explanatory diagram illustrating a plan view of a pier constructed as a temporary floating structure in a sea area, with multiple work areas established in the sea area adjacent to the floating structure. FIG. 3 is an explanatory diagram illustrating a plan view of the sea area where the floating structure of FIG. 2 is being constructed. FIG. 4 is an explanatory diagram illustrating an enlarged side view of a portion of the floating structure of FIG. 2. FIG. 5 is an explanatory diagram illustrating an enlarged side view of a portion of the floating structure of FIG. 2. FIG. 6 is an explanatory diagram illustrating a plan view of a concrete pouring guide jig used in the construction work of the floating structure. FIG. 7 is an explanatory diagram illustrating a side view of the concrete pouring guide jig of FIG. 6. FIG. 8 is an explanatory diagram illustrating a side view of a superstructure panel unit constituting the floating structure of FIG. 2. Figure 9 is an explanatory diagram illustrating, in a plan view, the state in which the integrated girder and support girder constituting the superstructure panel unit of Figure 8 is separated from the deck slab constituting the superstructure panel unit. Figure 10 is an explanatory diagram illustrating, in a plan view, a self-elevating barge having a crane and a concrete driving auxiliary device mounted on the barge body, and having a driving guide jig, support piles, superstructure panel units, a top plate, support members, and a pile driving device loaded on the barge body. Figure 11 is an explanatory diagram illustrating, in a cross-sectional view, the state in which the pile guide unit of the concrete driving auxiliary device of Figure 10 is arranged on the barge body. Figure 12 is an explanatory diagram illustrating, in a plan view, the state in which the pile guide unit of the concrete driving auxiliary device has been moved outside the barge body from the state in Figure 11 and the opening / closing unit of the pile guide unit has been opened. Figure 13 is an explanatory diagram illustrating, in a plan view, the state in which the pile guide unit of the concrete driving auxiliary device has been moved further outside the barge body from the state in Figure 12, and a support pile has been inserted through the pile guide unit and the opening / closing unit has been closed. 14 is an explanatory diagram illustrating a cross-sectional view of the driving assist device and support piles in the state of FIG. 13. FIG. 15 is an explanatory diagram illustrating a plan view of the driving assist device of FIG. 10 and a pile driving device suspended by a crane on a self-lifting barge, in which a first support pile serving as a reference for positioning is being driven. FIG. 16 is an explanatory diagram illustrating a cross-sectional view of the state of FIG. 15. FIG. 17 is an explanatory diagram illustrating a plan view of the driving assist device and a pile driving device suspended by a crane, in which a second support pile serving as a reference for positioning is being driven from the state of FIGS. 15 and 16.18 is an explanatory diagram illustrating, in a plan view, the state in which, after driving the third support pile serving as a positioning reference from the state of FIG. 17 , a crane is used to lower the driving guide jig from above the three support piles serving as a positioning reference, and the support piles are inserted into each of the three pile insertion portions of the driving guide jig. FIG. 19 is an explanatory diagram illustrating, in a cross-sectional view, the state of FIG. 18 . FIG. 20 is an explanatory diagram illustrating, in a cross-sectional view, the state in which, from the states of FIGS. 18 and 19 , the driving guide jig is placed on the bottom ground, and the fourth support pile is driven using the pile insertion portion into which no support pile has been inserted as a guide. FIG. 21 is an explanatory diagram illustrating, in a plan view, the state of FIG. 20 . FIG. 22 is an explanatory diagram illustrating, in a plan view, the state in which, after driving the fourth to sixth support piles from the states of FIGS. 20 and 21 , the driving guide jig is moved and the seventh support pile is driven. Figure 23 is an explanatory diagram illustrating, in plan view, the state in which the eighth and ninth support piles have been driven from the state of Figure 22, the driving guide jigs have been removed, and the piles have been loaded onto a self-elevating barge, and top plates have been installed on the upper ends of each support pile driven into the waterbed. Figure 24 is an explanatory diagram illustrating, in cross section, the state of Figure 23. Figure 25 is an explanatory diagram illustrating, in plan view, the state in which a crane is used to install a first set of superstructure panel units on top of multiple support piles after top plates have been installed on each support pile driven into the waterbed from the states of Figures 23 and 24. Figure 26 is an explanatory diagram illustrating, in cross section, the state of Figure 25. 27 is an explanatory diagram illustrating, in a plan view, the state in which, after completing the installation of the first set of superstructure panel units from the state of FIGS. 25 and 26 and completing the driving of support piles that serve as a reference for positioning the second and third sets of superstructure panel units, the driving guide jig is placed on the bottom ground with the support piles inserted into each of the two pile insertion portions of the driving guide jig, and the support piles are driven using the pile insertion portions into which the support piles are not inserted as guides. Figure 28 is an explanatory diagram illustrating, in a plan view, the state in which, after completing the driving of support piles that serve as a reference for positioning the second and third sets of superstructure panel units from the state of FIG. 27 and completing the installation of the second and third sets of superstructure panel units on top of multiple support piles, the third load of components is loaded onto a self-elevating barge, the self-elevating barge is moved, stopped, and the support piles that serve as a reference for positioning the fourth to sixth sets of superstructure panel units are driven.Figure 29 is an explanatory diagram illustrating, in a plan view, the state in which the support piles serving as positioning references from the state of Figure 28 have been driven, and the support piles serving as positioning references have been inserted into the three pile insertion sections of the driving guide jig, and the driving guide jig is placed on the waterbed. Figure 30 is an explanatory diagram illustrating, in a plan view, the state in which all support piles for the fourth to sixth sets of superstructure panel units have been driven and the top plates have been installed, and the fourth set of superstructure panel unit has been installed on top of the multiple support piles, and then the fifth set of superstructure panel unit has been installed on top of the multiple support piles. Figure 31 is an explanatory diagram illustrating, in a plan view, the state in which multiple sets of wind turbine generator assembly components have been temporarily placed on the floating structure of Figure 2. Figure 32 is an explanatory diagram illustrating, in a plan view, the state in which a float has been landed on the waterbed in the first work area of ​​the floating structure of Figure 31, and a self-elevating barge has been moored in the first work area. FIG. 33 is an explanatory diagram illustrating the floating structure and the self-elevating barge of FIG. 32 in a side view. FIG. 34 is an explanatory diagram illustrating a state before the tower segments are erected using the crane of the self-elevating barge in a side view. FIG. 35 is an explanatory diagram illustrating a state after the tower segments have been erected using the crane of the self-elevating barge from the state of FIG. 34 in a side view. FIG. 36 is an explanatory diagram illustrating a state after the tower segments and the nacelle hub, which were temporarily placed on the floating structure, have been installed on the floating body using the crane of the self-elevating barge in a side view. FIG. 37 is an explanatory diagram illustrating a state after the blades have been attached to the nacelle hub in a plan view from the state of FIG. 36. FIG. 38 is an explanatory diagram illustrating a state after the self-elevating barge has been moved to the second work area from the state of FIG. 37 in a plan view. Figure 39 is an explanatory diagram illustrating, in plan view, the state in which the tower segments, the nacelle hub, and the blades that were temporarily placed on the floating structure have been installed on the floating body that has been landed on the water bottom of the second work area from the state in Figure 38. Figure 40 is an explanatory diagram illustrating, in plan view, the state in which the self-elevating barge has been moved to the third work area from the state in Figure 39.Figure 41 is an explanatory diagram illustrating, in a plan view, the state in which the tower segments, nacelle hub, and blades that were temporarily placed on the floating structure have been installed on the floating body that has been landed on the bottom of the water in the third work area, and the self-elevating barge has been moved to the first work area where a new floating body has been landed on the bottom of the water. Figure 42 is an explanatory diagram illustrating, in a plan view, the state in which the tower segments, nacelle hub, and blades that were temporarily placed on the floating structure have been installed on the floating body that has been landed on the bottom of the water in the first work area, and the self-elevating barge has been moved to the fourth work area. Figure 43 is an explanatory diagram illustrating, in a front view, another embodiment of a pier that is a floating structure. Figure 44 is an explanatory diagram illustrating, in a plan view, the state in which assembly components of a wind turbine generator are temporarily placed on a floating structure that constitutes a floating structure.

[0012] Hereinafter, a method for constructing a floating offshore wind power generation facility of the present invention will be described based on an embodiment shown in the drawings.

[0013] As illustrated in FIG. 1 , a floating offshore wind power generation facility 1 includes a float 2 moored in a target sea area for installation and a wind turbine 3 erected on the float 2. In the target sea area for installation, the float 2 is moored to the bottom (SB) of the water using mooring lines 7, anchors 8, or the like. As illustrated in FIG. 1 , the present invention is a construction method for a floating offshore wind power generation facility 1 in which the draft (DF) from the water surface to the bottom of the float 2 is 20 m or less when the float 2 is moored in the target sea area for installation. In other words, the present invention can be employed in the construction of floating offshore wind power generation facilities 1 of other types (semi-submersible, TLP, barge) other than the spar type. The present invention is particularly suitable for the construction of semi-submersible floating offshore wind power generation facilities 1. In the present invention, the integrated body of the float 2 and the wind power generation device 3 before mooring in the target sea area for installation is referred to as an assembly 9, and the assembly 9 in the moored state in the target sea area for installation is referred to as a floating offshore wind power generation facility 1.

[0014] This embodiment illustrates the construction of a semi-submersible floating offshore wind power generation facility 1. As illustrated in Fig. 1 , a semi-submersible float 2 is submerged in the sea to a predetermined draft DF and moored in a semi-submerged state. The wind turbine 3 has a nacelle hub 5 (a nacelle and hub integrated unit) installed on top of a tower 4 extending in the vertical direction, and multiple blades 6 radially arranged on the nacelle hub 5. Electrical equipment such as a generator, brakes, and gearbox are built into the nacelle hub 5, and power cables connected to the generator are arranged inside the tower 4.

[0015] This embodiment illustrates a wind turbine generator 3 having three blades 6 and a tower 4 configured with three segmented members 4a. The number of blades 6 provided in the wind turbine generator 3, the structure of the blades 6, the number of segmented members 4a configuring the tower 4, and the like are not limited to this embodiment.

[0016] The longitudinal length (height) of the tower 4 is approximately 80 m to 150 m, and the width (thickness) of the tower 4 is approximately 5 m to 15 m. The weight of the tower 4 is approximately 1000 t to 2000 t. The longitudinal length (height) of each segment 4 a is approximately 25 m to 50 m, and the weight of each segment 4 a is approximately 300 t to 700 t. The height of the nacelle hub 5 is approximately 8 m to 15 m, the longitudinal length is approximately 15 m to 25 m, and the width is approximately 7 m to 15 m. The weight of the nacelle hub 5 is approximately 600 t to 1000 t. The longitudinal length of one blade 6 is approximately 80 m to 150 m, and the weight of one blade 6 is approximately 50 t to 90 t.

[0017] The semi-submersible float 2 has a plurality of pillar-shaped columns 2a extending in the vertical direction and connectors 2b (so-called footing members) that connect the columns 2a to each other. The lower end of a tower 4 is fixed to one of the columns 2a that make up the semi-submersible float 2, so that the wind turbine generator 3 is erected on one column 2a. The upper end of the column 2a and the lower end of the tower 4 are joined by, for example, bolting or welding.

[0018] The float 2 is structured so that ballast water can be stored (filled) inside, and the draft and attitude of the float 2 can be adjusted by adjusting the amount of stored ballast water. The semi-submersible float 2 has a length and width of approximately 60 m to 100 m in plan view, and the height of the column 2a of the semi-submersible float 2 is approximately 25 m to 50 m. The structure of the float 2 is not limited to the configuration of this embodiment, and floats 2 of various other configurations can be used. When constructing a TLP-type floating offshore wind power generation facility 1, a known TLP-type float 2 is used, and when constructing a barge-type floating offshore wind power generation facility 1, a known barge-type float 2 is used.

[0019] The following describes the procedure for constructing the floating offshore wind power generation facility 1. In this construction method, temporary floating structures 10 are used to construct multiple floating offshore wind power generation facilities 1 in parallel.

[0020] As illustrated in Figures 2 to 4, this construction method involves constructing a temporary offshore structure 10 in an offshore area with a water depth D1 (depth from the water surface position WL to the water bottom SB) of 8 m to 20 m. In this embodiment, a pier 10A is constructed in the offshore area as the temporary offshore structure 10. This construction method can also be used to construct a floating structure in the offshore area as the temporary offshore structure 10. In this embodiment, an offshore structure 10 that is rectangular in plan view is illustrated. The offshore structure 10 is large enough to accommodate multiple sets of assembly parts, namely, the nacelle hub 5, blades 6, and tower 4 (divided members 4a) that make up the wind turbine generator 3, and is constructed to withstand the weight of the multiple sets of assembly parts that are temporarily placed.

[0021] In the figure, the longitudinal direction (left-right direction) of the floating structure 10 in a plan view is the X direction, the width direction (front-rear direction) of the floating structure 10 is the Y direction, and the up-down direction is the Z direction. As illustrated in Figure 2, in this embodiment, temporary mooring equipment 20 and temporary protection equipment 21 are provided near the floating structure 10 as equipment used to moor a carrier ship to the floating structure 10. Note that the mooring equipment 20 and protection equipment 21 are omitted and not shown in figures other than Figure 2. Figure 2 and Figures 31, 32, and 37 to 42, which will be described later, illustrate the floating structure 10 in a simplified form.

[0022] The offshore structure 10 is preferably constructed in a calm sea area where the influence of waves is small. As shown in Fig. 3, the offshore structure 10 is preferably constructed in a sea area inside a breakwater 80 installed in a bay or the like. The sea area inside the breakwater 80 here refers to a sea area where the influence of waves is reduced by the breakwater 80.

[0023] As shown in Figure 2, in this construction method, work areas A are provided in multiple locations in the sea area adjacent to the floating structure 10, where the assembly work of the assembly body 9 and subsequent additional work are performed. In this embodiment, six work areas A1 to A6 are provided in the sea area adjacent to the floating structure 10. The floating structure 10 in this embodiment is configured to be able to temporarily store eight sets of assembly parts for the wind turbine generator 3. The number of work areas A to be provided in the sea area adjacent to the floating structure 10 can be determined appropriately depending on the number of floating offshore wind power generation facilities 1 to be constructed.

[0024] The longitudinal length of the floating structure 10 in plan view is set to, for example, 150 m to 600 m, and the width is set to, for example, 50 m to 200 m. As shown in Fig. 4, the height H from the water surface position WL to the top surface of the floating structure 10 may be set to, for example, 1 m to 10 m. The load capacity of the floating structure 10 is, for example, 1 t / m 2 15t / m or more 2 The load capacity may be set as follows: The entire surface structure 10 may be set to the same load capacity, but different load capacities may be set for the area where the assembly parts of the wind turbine generator 3 are placed and the area where they are not. Also, different load capacities may be set for each temporary storage area for each assembly part of the wind turbine generator 3. Specifically, the load capacity of the area where the nacelle hub 5 is placed in the surface structure 10 may be set to, for example, 8 t / m 2 12t / m or more 2 Hereinafter, the load capacity of the area where the divided members 4a of the tower 4 are placed is, for example, 3 t / m 2 8t / m or more 2 Hereinafter, the load capacity of the area where the blade 6 is placed is, for example, 1 t / m 2 5t / m or more 2 It is recommended to set it as follows.

[0025] An example of a method for constructing the floating structure 10 will be described below.

[0026] As illustrated in Figures 4 and 5, in this embodiment, a pile driving operation for erecting a plurality of support piles 11 into the waterbed ground UG and a superstructure construction operation for constructing a superstructure 12 on top of the plurality of support piles 11 are performed consecutively to construct an overwater structure 10 in which the plurality of support piles 11 and the superstructure 12 are integrated. In the superstructure construction operation described above, the superstructure 12 is constructed by installing superstructure panel units 13 on top of the plurality of support piles 11 driven into the waterbed ground UG. In this embodiment, a top plate 18 is installed on the top end of each support pile 11, and the superstructure panel units 13 are installed on top of the top plate 18. The top plate 18 can be installed as desired. As illustrated in Figure 2, this embodiment illustrates the case in which the superstructure 12 is constructed using 12 sets of superstructure panel units 13.

[0027] As illustrated in Figure 4, the insertion depth D2 of the support pile 11 into the water bottom ground UG can be determined appropriately depending on the strength of the water bottom ground UG and the load-bearing capacity required of the abovewater structure 10. The insertion depth D2 of the support pile 11 is, for example, 10 m or more and 30 m or less.

[0028] As illustrated in Figure 5, in the pile driving work of this construction method, multiple support piles 11 are driven into the waterbed ground UG at intervals in plan view. The support piles 11 may be, for example, steel pipe piles with an outer diameter of 500 mm to 3000 mm and a thickness of 10 mm to 50 mm. Other prefabricated piles, such as concrete piles, may also be used as the support piles 11. The length (height) of the support piles 11 can be determined appropriately depending on the strength of the waterbed ground UG and the height of the abovewater structure 10 to be constructed, but may be set to, for example, 20 m to 60 m.

[0029] In this embodiment, the support piles 11 are arranged in 14 rows with a spacing L1 between them in the X direction and in 5 rows with a spacing L2 between them in the Y direction. The X-direction spacing L1 and the Y-direction spacing L2 between adjacent support piles 11 are each set to, for example, 10 m or more and 30 m or less, more preferably 13 m or more and 27 m or less, and even more preferably 15 m or more and 25 m or less. In this embodiment, the X-direction spacing L1 and the Y-direction spacing L2 between adjacent support piles 11 are set to the same distance. The number and arrangement of the support piles 11 driven into the waterbed ground UG are not particularly limited as long as the spacing (L1, L2) between adjacent support piles 11 is a predetermined constant distance, and can be determined appropriately depending on the size and shape of the floating structure 10 to be constructed. For example, the X-direction spacing L1 and the Y-direction spacing L2 between adjacent support piles 11 can be set to different spacing distances.

[0030] 6 and 7, in this construction method, a driving guide jig 40 is used in the pile driving work. The driving guide jig 40 has a plurality of pile insertion sections 41 arranged at intervals from one another in a plan view. The pile insertion sections 41 are configured as tubular bodies having through holes through which the support piles 11 can be inserted in the Z direction. The inner diameter of the through holes of the pile insertion sections 41 is set to be slightly larger (for example, approximately 5 cm to 30 cm) than the outer diameter of the support piles 11.

[0031] In this embodiment, the driving guide jig 40 has two rows of pile insertion portions 41 arranged in the front-to-back direction (Y direction) and three rows of pile insertion portions 41 arranged in the left-to-right direction (X direction) in a plan view. The pile insertion portions 41 are fixed in a predetermined arrangement by connecting portions 45. The distance L1 between adjacent pile insertion portions 41 in the X direction (the centers of the pile insertion portions 41 in a plan view) is set to the same distance as the distance L1 between adjacent support piles 11 in the X direction (the centers of the support piles 11 in a plan view) that are driven into the waterbed ground UG. The distance L2 between adjacent pile insertion portions 41 in the Y direction (the centers of the pile insertion portions 41 in a plan view) is set to the same distance as the distance L2 between adjacent support piles 11 in the Y direction (the centers of the support piles 11 in a plan view) that are driven into the waterbed ground UG.

[0032] That is, the intervals L1, L2 between adjacent pile insertion portions 41 are set to the same distance as the intervals L1, L2 between the support piles 11 to be driven into the planned bottom ground UG in advance. In this embodiment, the interval L1 between adjacent pile insertion portions 41 in the X direction and the interval L2 between adjacent pile insertion portions 41 in the Y direction are set to the same distance.

[0033] 4 and 5, in this embodiment, a cylindrical enlarged head 42 is provided on top of each pile insertion portion 41, the diameter of which increases in a tapered manner from the upper end of the pile insertion portion 41 toward the top. A cylindrical enlarged bottom portion 43 is provided below each pile insertion portion 41, the diameter of which increases in a tapered manner from the lower end of the pile insertion portion 41 toward the bottom. In this embodiment, a subsidence suppression portion 44 is further provided below the enlarged bottom portion 43 to suppress sinking of the driving guide jig 40 (pile insertion portion 41) into the water bottom ground UG.

[0034] The pouring guide jig 40 of this embodiment is provided with a lifting tool 46 used to lift the pouring guide jig 40. The pouring guide jig 40 is also provided with a receiving tool 47 on which the lifting tool 46 is placed when not connected to the wire rope 33a of the crane 33.

[0035] Considering workability, it is preferable to use a driving guide jig 40 in which the pile insertion sections 41 are arranged in two rows in the front-to-back direction and three rows in the left-to-right direction in a plan view, as in this embodiment, but the number and arrangement of the pile insertion sections 41 that make up the driving guide jig 40 are not limited to this embodiment. In the driving guide jig 40, the enlarged head section 42, enlarged base section 43, subsidence suppression section 44, lifting device 46, and receiving device 47, other than the pile insertion sections 41 and connecting section 45, are not essential components and can be provided as needed. Details of pile driving work using the driving guide jig 40 will be described later.

[0036] As illustrated in Figures 4, 5, 8, and 9, the superstructure panel unit 13 used in constructing the superstructure 12 has a floor structure 14 extending across multiple support piles 11, and multiple support girders 17 arranged at intervals from each other in a plan view below the floor structure 14. In this embodiment, the superstructure panel unit 13 extends across a total of nine support piles 11 arranged in three rows in each of the X and Y directions.

[0037] 8, in this embodiment, a plurality of support girders 17 extending in the Y direction are arranged at intervals L1 in the X direction. The interval L1 between adjacent support girders 17 (the centers of the support girders 17 in the width direction) is set to the same distance as the interval L1 between adjacent support piles 11 in the X direction (the centers of the support piles 11 in a plan view) that are driven into the waterbed ground UG.

[0038] The floor structure 14 of this embodiment is composed of multiple girder members 15 arranged on support girders 17 and a deck slab 16 (covering plates 16a) fixed onto the girder members 15. Each girder member 15 extends across multiple support girders 17. The sizes (dimensions) of the support girders 17 and the girder members 15 can be determined as appropriate, but the support girders 17 and the girder members 15 are preferably composed of I-beams with a height of 700 mm to 2000 mm and a width of 300 mm to 800 mm. The support girders 17 and the girder members 15 can also be composed of other steel materials, such as H-beams or channel steel. In this embodiment, the deck slab 16 is composed of multiple covering plates 16a, but the deck slab 16 can also be composed of, for example, metal plate-like members.

[0039] FIG. 9 shows the superstructure panel unit 13, which is composed of a single unit of girders 15 and support girders 17, separated from the deck slab 16. When the superstructure panel unit 13 is assembled, the deck slab 16 is fixed on top of the single unit of girders 15 and support girders 17. In this embodiment, multiple girders 15 extending in the X direction are arranged on top of the support girders 17 at intervals in the Y direction, forming a lattice frame. Each overlapping support girder 17 and multiple girders 15 are joined, for example, by welding or bolting. The Y-direction spacing between adjacent girders 15 (the centers of the girders 15 in the width direction) is, for example, between 1 m and 5 m, and is preferably set to match the Y-direction width of the covering plate 16a that constitutes the deck slab 16. Details of the superstructure construction work using the superstructure panel unit 13 will be described later.

[0040] As shown in Figure 10, in this embodiment, construction work (pile driving work and superstructure construction work) for the offshore structure 10 is carried out using a self-elevating barge 30. In the following description, the self-elevating barge 30 used for construction work for the offshore structure 10 will be referred to as a self-elevating barge 30A (hereinafter referred to as SEP vessel 30A). The SEP vessel 30A has lifting legs 32, a barge body 31 that can be raised and lowered relative to the lifting legs 32, and a crane 33 mounted on the barge body 31.

[0041] In this embodiment, a pile driving device 34 used in the pile driving work is loaded onto the SEP vessel 30A. The pile driving device 34 is a device that drives the support piles 11 into the waterbed ground UG by applying impact or vibration to the pile head of the support pile 11, and a known device such as a vibro hammer is used for this purpose.

[0042] 10, in this embodiment, the SEP vessel 30A is equipped with a driving assist device 50 used to drive the support piles 11 that serve as a positioning reference. The driving assist device 50 is disposed near the side of the barge main body 31 of the SEP vessel 30A.

[0043] 11 to 14, the driving auxiliary device 50 includes a pile guide unit 51 through which the support pile 11 is inserted, and a movement mechanism 52 that moves the pile guide unit 51 relative to the barge body 31 of the SEP vessel 30A. As shown in Figures 12 and 13, the pile guide unit 51 of this embodiment is provided with a pair of opening / closing units 51a at the front, and the front units (opening / closing units 51a) of the pile guide unit 51 can be opened and closed by a switching mechanism 51b.

[0044] 13 and 14 , when the opening / closing unit 51a is closed, the pile guide unit 51 is cylindrical. When the support pile 11 is inserted into the pile guide unit 51, the vertical movement of the support pile 11 relative to the pile guide unit 51 is not restricted, but the horizontal movement of the support pile 11 relative to the pile guide unit 51 is restricted. When the opening / closing unit 51a is opened by the switching mechanism 51b, the constraint of the support pile 11 by the pile guide unit 51 is released.

[0045] The moving mechanism 52 in this embodiment is composed of a first moving mechanism 53 that moves the pile guide section 51 in the width direction (Y direction) of the SEP vessel 30A, a second moving mechanism 55 that moves the pile guide section 51 in the up and down direction (Z direction), and a third moving mechanism 60 that moves the pile guide section 51 in the length direction (X direction) of the SEP vessel 30A.

[0046] The first moving mechanism 53 is composed of an actuator 54 extending in the ship's width direction. The actuator 54 is composed of, for example, a hydraulic cylinder or a pneumatic cylinder in which a rod 54b is extendable (movable forward and backward) relative to a cylinder 54a. The rear end of the pile guide part 51 is connected to the front end of the actuator 54 (rod 54b).

[0047] The second movement mechanism 55 is composed of a rotating part 56 to which the rear end of the actuator 54 is fixed, a lifting part 57 to which the rotating part 56 is rotatably connected, a support part 58 that supports the lifting part 57 so that it can move up and down in the vertical direction, and a lifting guide 59 that guides the lifting part 57's lifting and lowering movement relative to the support part 58. The third movement mechanism 60 is composed of a longitudinal movement rail 61 that extends in the longitudinal direction and is laid on the barge main body 31, and a movable base 62 that can move in the longitudinal direction on the longitudinal movement rail 61. The support part 58 is fixed on top of the movable base 62. The longitudinal movement rail 61 is laid near the side of the barge main body 31. The opening and closing operation of the opening / closing section 51a by the switching mechanism 51b and the movement of the pile guide section 51 by the first moving mechanism 53, the second moving mechanism 55 and the third moving mechanism 60 can be remotely controlled by a controller from on board the SEP vessel 30A.

[0048] Note that the pile guide unit 51 is not limited to the configuration of this embodiment and can have various other configurations as long as it is configured to restrict horizontal movement without restricting vertical movement of the support pile 11 when the support pile 11 is inserted. The opening / closing unit 51a and the switching mechanism 51b are not essential components of the pile guide unit 51 and can be provided optionally. The moving mechanism 52 is not limited to the configuration of this embodiment and can have various other configurations as long as it is configured to move the pile guide unit 51 to a desired position outside the SEP vessel 30A. The arrangement of the crane 33 and the driving auxiliary device 50 on the barge main body 31 is not particularly limited.

[0049] Next, a description will be given of specific work procedures for constructing the floating structure 10. In the following description, the area in which one set of superstructure panel units 13 is installed in plan view will be referred to as one section of the floating structure 10.

[0050] In this embodiment, the driving assist device 50 is used in the reference pile driving step of driving the support pile 11 that serves as a reference for positioning in the pile driving work, and the driving guide jig 40 is used in the post-driving step of driving the other support piles 11 that follow the reference pile driving step. The reference pile driving step can also be performed using the driving guide jig 40 without using the driving assist device 50, but this case will be described later.

[0051] In the first voyage, the SEP vessel 30A constructs one section of the floating structure 10 illustrated in Figure 2. As illustrated in Figure 10, a driving auxiliary device 50 is mounted on the barge body 31 of the SEP vessel 30A, and a pile driving device 34 and a driving guide jig 40 are loaded on the barge body 31. The barge body 31 is also loaded with support piles 11, superstructure panel units 13, top plates 18, and support members 19 used to construct one section of the floating structure 10. The superstructure panel units 13 may be fabricated in advance on land or on board the vessel before the SEP vessel 30A moves to the construction waters. The SEP vessel 30A loaded with the materials described above is moved to the construction waters where the floating structure 10 will be constructed.

[0052] 15 and 16 , in the reference pile driving step of the pile driving work, the SEP vessel 30A is stopped in a jacked-up state near the position where the support pile 11, which serves as the positioning reference, will be driven. As shown in FIG. 16 , when the SEP vessel 30A is stopped in a jacked-up state, the lifting legs 32 are moved downward relative to the barge body 31, which is floating in the water, so that the lower ends of the lifting legs 32 are seated on the bottom ground UG. From this state, the barge body 31 is moved upward relative to the lifting legs 32, so that the barge body 31 is moved to a position higher than the water surface level WL, and the barge body 31 is supported in midair by the lifting legs 32.

[0053] 15 and 16 , the movement mechanism 52 of the driving assist device 50 is used to position the pile guide unit 51 above the water at the planned driving position of the first support pile 11, which serves as a positioning reference. In this embodiment, as illustrated in FIGS. 13 and 14 , the actuator 54 is extended in the Y direction, and the pile guide unit 51 is operated to move the pile guide unit 51 in the Y direction, thereby moving the pile guide unit 51 above the water to the planned driving position of the first support pile 11. The position of the pile guide unit 51 in the X direction is adjusted by moving the movable base 62 in the X direction relative to the ship-lengthwise movement rail 61. The position of the pile guide unit 51 in the Z direction is adjusted by moving the lifting unit 57 in the Z direction relative to the support unit 58. The opening / closing unit 51 a of the pile guide unit 51 is kept closed.

[0054] Next, the crane 33 is used to move the first support pile 11 loaded on the SEP vessel 30A in an upright position above the pile guide unit 51. The support pile 11 is then lowered so that it is inserted into the pile guide unit 51 and the lower end of the support pile 11 is placed on the waterbed ground UG. After that, the support pile 11 is released from its suspended state by the crane 33, and the pile driving device 34 is suspended by the crane 33. The pile driving device 34 suspended by the crane 33 then applies vibration or impact to the head of the support pile 11, thereby driving the support pile 11 into the waterbed ground UG. While the support pile 11 is being driven, the pile guide unit 51 restricts horizontal movement of the support pile 11.

[0055] After completing the driving of the first support pile 11, which serves as a reference for positioning, the second moving mechanism 55 of the driving assist device 50 is used to move the pile guide unit 51 above the upper end of the support pile 11 driven into the waterbed ground UG, thereby removing the pile guide unit 51 from the support pile 11. When the pile guide unit 51 is provided with the opening / closing unit 51a and the switching mechanism 51b as in this embodiment, the opening / closing unit 51a can be opened by the switching mechanism 51b, and the pile guide unit 51 can be moved toward the SEP vessel 30A by the first moving mechanism 53 (actuator 54), thereby removing the pile guide unit 51 from the support pile 11.

[0056] Next, as shown in Figure 17, the moving mechanism 52 of the driving assist device 50 places the pile guide unit 51 on the water at the planned driving position of the second support pile 11, which will serve as the positioning reference. In this embodiment, the movable platform 62 constituting the third moving mechanism 60 shown in Figure 13 is moved in the X direction along the ship's longitudinal movement rail 61, so that the pile guide unit 51 is placed at a distance L1 in the X direction from the first support pile 11 driven into the waterbed ground UG. The opening / closing part 51a of the pile guide unit 51 is kept in a closed state.

[0057] Then, in the same manner as the driving of the first support pile 11, the second support pile 11 loaded on the SEP vessel 30A is inserted into the pile guide unit 51, and the second support pile 11 is driven into the waterbed ground UG by the pile driving device 34. After the driving of the second support pile 11 is completed, the pile guide unit 51 is removed from the support pile 11. Similarly, the movement mechanism 52 of the driving auxiliary device 50 positions the pile guide unit 51 on the water at the planned driving position of the third support pile 11, which will be used as a positioning reference. Then, the third support pile 11 is inserted into the pile guide unit 51, and the third support pile 11 is driven into the waterbed ground UG by the pile driving device 34. After the driving of the third support pile 11 is completed, the pile guide unit 51 is removed from the support pile 11, and the pile guide unit 51 is stored on the barge main body 31. The above work completes the reference pile driving process for the pile driving work on the first voyage.

[0058] 18 and 19, in the post-driving step of the pile driving work, the driving guide jig 40 loaded on the SEP vessel 30A is suspended by the crane 33. The crane 33 is then operated to move the driving guide jig 40 above the first to third support piles 11, which serve as references for positioning the piles driven into the waterbed ground UG. In this embodiment, the driving guide jig 40 is suspended with the wire rope 33a of the crane 33 connected to a hoisting tool 46 attached to the driving guide jig 40.

[0059] Next, the crane 33 lowers the casting guide jig 40, and one support pile 11, which serves as a positioning reference, is inserted into each of the three pile insertion sections 41 located on the SEP vessel 30A side. Then, as shown in Figure 20, the casting guide jig 40 is lowered into the water, and the casting guide jig 40 is placed on the waterbed ground UG. After the casting guide jig 40 has been placed on the waterbed ground UG, the connection between the wire rope 33a of the crane 33 and the hoisting tool 46 is released, and the hoisting tool 46 is placed on the receiving tool 47.

[0060] By leaving the support piles 11 inserted through the three pile insertion portions 41 of the driving guide jig 40, the remaining three pile insertion portions 41 are positioned at the planned driving positions of the fourth to sixth support piles 11 to be driven subsequently. Also, by having the support piles 11 driven into the waterbed ground UG inserted through the three pile insertion portions 41, respectively, horizontal movement of the driving guide jig 40 is restricted.

[0061] Next, as illustrated in Figures 20 and 21, the fourth support pile 11 loaded on the SEP vessel 30A is driven. Using a crane 33, the fourth support pile 11 is moved above the pile insertion portion 41 into which the first to third support piles 11 have not yet been inserted. The fourth support pile 11 is then lowered so that the support pile 11 is inserted into the pile insertion portion 41, with the lower end of the support pile 11 placed on the waterbed ground UG. The support pile 11 can be guided into the pile insertion portion 41 using an ROV (remotely operated underwater vehicle) or seabed sonar, as needed. However, because the pile insertion portion 41 is positioned at the planned driving position for the support pile 11, it is also possible to insert the support pile 11 into the expansion head portion 42 and the pile insertion portion 41 by guiding it on the water.

[0062] Next, the fourth support pile 11 is driven into the water bottom ground UG using a pile driving device 34 suspended by a crane 33. While the support pile 11 is being driven, the horizontal movement of the support pile 11 is restricted by the pile insertion portion 41. Similarly, the fifth and sixth support piles 11 are driven into the water bottom ground UG in sequence, using the remaining two pile insertion portions 41 into which no support piles 11 have been inserted.

[0063] During the subsequent driving of the seventh support pile 11, the crane 33 is used to move the driving guide jig 40 above the upper ends of the six support piles 11 driven into the waterbed ground UG, and the driving guide jig 40 is removed from the six support piles 11. Then, as illustrated in Figure 22, the driving guide jig 40 is moved in the direction away from the SEP vessel 30A (Y direction), so that the fourth to sixth support piles 11 that have already been driven are inserted into the three pile insertion sections 41 located on the SEP vessel 30A side, respectively, and the driving guide jig 40 is placed on the waterbed ground UG with the previously driven support piles 11 not being inserted into the remaining three pile insertion sections 41. The pile insertion sections 41 that have not yet had a support pile 11 inserted therein are then positioned at the planned driving positions for the seventh to ninth support piles 11 to be driven subsequently.

[0064] In the driving work of the seventh to ninth support piles 11, similar to the work of driving the fourth to sixth support piles 11, the seventh to ninth support piles 11 are driven into the waterbed ground UG with each supported by a pile insertion portion 41. Then, as shown in Figure 23, after the driving work of the seventh to ninth support piles 11 is completed, the driving guide jigs 40 are removed from the six support piles 11 using a crane 33, and the driving guide jigs 40 are placed on the barge body 31 of the SEP vessel 30A. By performing the post-driving process described above, the pile driving work for the first voyage of the SEP vessel 30A is completed, and a total of nine support piles 11 are erected in the construction waters, in three rows in each of the X and Y directions.

[0065] When pile driving work is performed without using the driving assist device 50, the planar position of the pile insertion portion 41 of the driving guide jig 40 is positioned to match the planned driving position of the support pile 11, and the driving guide jig 40 is placed on the water bottom ground UG. Then, the first support pile 11 is driven with the first support pile 11 inserted into one of the pile insertion portions 41 of the driving guide jig 40. Thereafter, the second and third support piles 11 are driven with the support piles 11 inserted into the pile insertion portions 41 that the first support pile 11 has not yet passed through. Thereafter, the fourth and subsequent support piles 11 are driven using the same work procedure as in the post-driving process described above.

[0066] As illustrated in Figures 23 and 24 , after the pile driving work is completed, pile head processing is performed to adjust the height of the top ends of each support pile 11 driven into the waterbed ground UG. In pile head processing, leveling adjustment is performed to make the top end heights of the support piles 11 the same, and then multiple support members 19 are attached to the inside of the pile head of each support pile 11 by welding or the like. Then, using a crane 33 or the like, a top plate 18 is placed on the top ends of the support piles 11 and the support members 19, and the top plate 18 is joined to the support pile 11 by welding or the like. By performing pile head processing, the heights of the top ends (top plate 18) of the support piles 11 become the same, and a level foundation is constructed on which the superstructure panel units 13 are to be installed.

[0067] 25 and 26 , in the subsequent superstructure construction work, a crane 33 is used to move the superstructure panel unit 13 loaded on the SEP vessel 30A to above the multiple support piles 11 driven into the bottom ground UG. Then, the superstructure panel unit 13 is lowered from above the support piles 11, and each of the support girders 17 constituting the superstructure panel unit 13 is placed on the multiple support piles 11. In this embodiment, the superstructure panel unit 13 extending across a total of nine support piles 11 arranged in three rows in each of the X and Y directions is placed on the nine support piles 11, and each of the three support girders 17 constituting the superstructure panel unit 13 is placed on each of the three support piles 11.

[0068] In this embodiment, the support girders 17 that constitute the superstructure panel units 13 are placed on the top plates 18 provided at the upper ends of the respective support piles 11. The load of one set of superstructure panel units 13 is then supported by nine support piles 11. Thereafter, the superstructure panel units 13 are fixed to the respective support piles 11 (top plates 18) by welding, bolting, or the like, as necessary. In this embodiment, the support girders 17 and top plates 18 that constitute the superstructure panel units 13 are joined by welding, thereby fixing the superstructure panel units 13 onto the support piles 11. With the above work, the superstructure construction work for the first voyage by the SEP vessel 30A is completed, and the construction of one section of the floating structure 10 is completed.

[0069] As illustrated in Figure 27, in the second voyage work by the SEP vessel 30A, two sections adjacent to the first section of the already constructed floating structure 10 are constructed. In the second voyage, the support piles 11, superstructure panel units 13, top plates 18, and support members 19 used to construct the two sections of the floating structure 10 are loaded onto the barge body 31 of the SEP vessel 30A. The materials to be newly loaded onto the SEP vessel 30A may be transported by temporarily moving the SEP vessel 30A from the construction waters, or the materials transported by another transport vessel may be transferred onto the SEP vessel 30A while the SEP vessel 30A is anchored in the construction waters.

[0070] Similarly, in the second voyage, in the reference pile driving process of the pile driving work, the support piles 11 serving as the positioning reference are sequentially driven using the driving auxiliary device 50 and the pile driving device 34. In the subsequent post-driving process of the pile driving work, the remaining support piles 11 are driven using a driving guide jig 40, as illustrated in FIG. 27 . A total of 12 support piles 11 are erected in the construction waters next to one section of the floating structure 10 constructed in the first voyage, in four rows in the X direction and three rows in the Y direction. Next, pile head processing is performed to adjust the top height of each support pile 11 driven into the waterbed ground UG. In the subsequent superstructure construction work, the crane 33 is used to install and secure two sets of superstructure panel units 13 loaded on the SEP vessel 30A on top of the support piles 11 driven into the waterbed ground UG. This completes the construction of the second and third sections of the floating structure 10, and the superstructure construction work for the second voyage by the SEP vessel 30A is completed.

[0071] In the third voyage, the SEP vessel 30A will construct three sections adjacent to the three sections of the already constructed floating structure 10. As illustrated in Figure 28, in the third voyage, the barge body 31 of the SEP vessel 30A will be loaded with support piles 11, superstructure panel units 13, top plates 18, and support members 19 to be used in constructing the three sections of the floating structure 10.

[0072] Similarly, in the work on the third voyage, in the reference pile driving step of the pile driving work, the support piles 11 serving as the reference for positioning are sequentially driven using the driving assist device 50 and the pile driving device 34. In the post-driving step of the subsequent pile driving work, the remaining support piles 11 are driven using the driving guide jig 40. In the construction waters, a total of 14 support piles 11 are erected in seven rows in the X direction and two rows in the Y direction, next to the three sections of the floating structure 10 constructed on the first and second voyages.

[0073] After the pile driving work for the third voyage is completed, pile head processing is performed to adjust the top height of each support pile 11 driven into the waterbed ground UG. As illustrated in Figure 30, in the subsequent superstructure construction work, a crane 33 is used to install and secure each of the three sets of superstructure panel units 13 loaded on the SEP vessel 30A onto the support piles 11 driven into the waterbed ground UG. This completes the construction of the fourth to sixth sections of the floating structure 10, and the superstructure construction work for the third voyage by the SEP vessel 30A is completed. In this embodiment, the support girders 17 of the floating structure panel units 13 constituting each section are placed adjacent to the support piles 11 located at the boundaries of adjacent sections of the floating structure 10. By similarly constructing the remaining six sections of the floating structure 10, the construction work for the floating structure 10 with a total of 12 sections is completed.

[0074] Next, we will explain the assembly work and additional work of the assembly 9 that are performed after the construction of the offshore structure 10. In this embodiment, we will explain the case where the assembly work of the assembly 9 is performed using a self-elevating barge 30B (hereinafter referred to as SEP vessel 30B) that is different from the self-elevating barge 30A (SEP vessel 30A) that was used in the construction work of the offshore structure 10.

[0075] The SEP vessel 30B used in the assembly work of the assembly 9 has, like the SEP vessel 30A used in the construction work of the floating structure 10, lifting legs 32, a barge body 31 that can be raised and lowered relative to the lifting legs 32, and a crane 33 mounted on the barge body 31. The SEP vessel 30B in this embodiment is not equipped with a concrete pouring auxiliary device 50. Note that the construction work of the floating structure 10 and the assembly work of the assembly 9 can also be performed using the same SEP vessel 30. In other words, the assembly work of the assembly 9 can also be performed using an SEP vessel 30 equipped with a concrete pouring auxiliary device 50.

[0076] As illustrated in Figure 31, in this embodiment, a first work area A1, a second work area A2, and a third work area A3 are provided on one side of the width of the floating structure 10, and a fourth work area A4, a fifth work area A5, and a sixth work area A6 are provided on the other side of the width of the floating structure 10. The first work area A1 and the fourth work area A4 are provided in the center of the floating structure 10 in the longitudinal direction. In the longitudinal direction of the floating structure 10, a second work area A2 is provided on one side of the first work area A1, and a third work area A3 is provided on the other side of the first work area A1. In the longitudinal direction of the floating structure 10, a sixth work area A6 is provided on one side of the fourth work area A4, and a fifth work area A5 is provided on the other side of the fourth work area A4.

[0077] The size of each work area A is set to be large enough to accommodate the floating body 2 and the SEP vessel 30B, and each work area A is provided with a landing area BA for landing the floating body 2 on the bottom and a mooring area SA for mooring the SEP vessel 30B. In the figure, the imaginary outer frame of each work area A is shown by a dot-dash line, and the imaginary outer frames of the landing area BA and the mooring area SA are shown by dashed lines. In each work area A, it is sufficient that at least the mooring area SA is adjacent to the surface structure 10, and the landing area BA may be separated from the surface structure 10.

[0078] Preferably, buoys or the like are installed in the sea area to visualize the extent of each work area A (bottom landing area BA, mooring area SA). Note that it is sufficient that the extent and boundaries of each work area A are understood by the workers and managers involved in the construction, and it is not essential to visualize the extent of each work area A in the sea area.

[0079] In this construction method, after the floating structure 10 is constructed, a transport vessel (specifically, for example, a LOLO vessel) equipped with a crane is used to transport multiple sets of assembly parts, i.e., the nacelle hub 5, the blades 6, and the tower 4 (segment members 4a) that constitute the wind turbine generator 3, to the floating structure 10. Then, using the crane of the transport vessel, the transported sets of assembly parts are temporarily placed on the floating structure 10, as shown in Fig. 31 . It is preferable to transport the assembly parts of the wind turbine generator 3 by sea to the floating structure 10, but when the floating structure 10 is constructed in a sea area close to a quay 90, it is also possible to transport (load and unload) the assembly parts from the quay 90 to the floating structure 10, for example, using a crane 71 placed on the floating structure 10 or a crane placed on the quay 90.

[0080] As illustrated in Figure 31, in this embodiment, assembly parts for eight wind turbine generators 3, i.e., eight sets of assembly parts, are temporarily placed on the floating structure 10. Furthermore, in this embodiment, a work platform 72 (SPMT: multi-axle platform) equipped with a mobile crane 71, a tower lift hoisting device 70, and an erection device 73 is placed on the floating structure 10. The tower lift hoisting device 70 and the erection device 73 will be described in detail later. In this embodiment, a travel path RW for the crane 71 extending in the longitudinal direction of the floating structure 10 is provided in the center of the floating structure 10, and assembly parts for the wind turbine generators 3 are temporarily placed on both sides of the travel path RW. The assembly parts for the wind turbine generator 3 are temporarily placed near each of the work areas A1 to A6, with the assembly parts for one wind turbine generator 3 being collected together.

[0081] In this embodiment, a pedestal supporting the nacelle hub 5 is provided on the floating structure 10, and the nacelle hub 5 is placed on the pedestal. The floating structure 10 is also provided with pedestals supporting each of the segmented members 4a constituting the tower 4, and the segmented members 4a are placed on the pedestal in a horizontally-tilted state. In this embodiment, three segmented members 4a constituting one tower 4 are arranged side by side. Furthermore, the floating structure 10 is provided with a pedestal structure capable of mounting multiple blades 6 spaced apart from one another, and the multiple blades 6 are arranged vertically side by side. Each blade 6 is arranged side by side, and a portion of the blade 6 located at the edge of the floating structure 10 protrudes from the floating structure 10. In other words, the floating structure 10 may be large enough to allow some of the blades 6 constituting the wind turbine generator 3 to protrude.

[0082] In this embodiment, two sets of assembly parts are temporarily placed near each of the first and fourth work areas A1 and A4, and one set of assembly parts is temporarily placed near each of the second, third, fourth, and fifth work areas A2, A3, A4, and A5.

[0083] After the assembly components of the wind turbine generator 3 have been temporarily placed on the floating structure 10, the transport vessel is departed from the floating structure 10. Thereafter, as illustrated in Figure 32, the floating body 2 is transported by sea and brought into a state in which it is landed on the water bottom SB of the bottom landing area BA of each work area A (A1 to A6) in sequence. Then, the SEP vessel 30B is brought into a state in which it is moored in any of the work areas A. In this embodiment, first, the floating body 2 is brought into a state in which it is landed on the water bottom SB of the bottom landing area BA of the first work area A1, and the SEP vessel 30B is moored in the mooring area SA of the first work area A1.

[0084] During marine transportation, the float 2 is set afloat on the sea with a relatively small amount of ballast water stored therein, and is towed to the vicinity of the floating structure 10 using a tugboat or the like. After the float 2 is moved to the bottom-attaching area BA, ballast water is poured into the float 2, causing the float 2 to gradually sink until its bottom is anchored to the water bottom SB. The float 2 is preferably positioned so that the columns 2a on which the wind turbine generators 3 are erected are positioned on the floating structure 10 side and the mooring area SA side.

[0085] In this construction method, the floating structure 10 is constructed in a sea area with a water depth D1 of 8 m or more and 20 m or less, so that the semi-submersible floating body 2, the TLP floating body 2, and the barge floating body 2 can be towed to the work area A near the floating structure 10. Furthermore, because the water depth D1 is 8 m or more and 20 m or less, each type of floating body 2 can be easily landed on the water bottom SB, and assembly components of the wind turbine generator 3 can be installed on the floating body 2 when it is landed on the water bottom SB. In other words, in sea areas with a water depth D1 of less than 8 m, the water depth D1 is too shallow, making it difficult to tow the floating body 2 near the floating structure 10. In sea areas with a water depth D1 of more than 20 m, the water depth D1 is too deep, making it difficult to install assembly components of the wind turbine generator 3 on the floating body 2 when it is landed on the water bottom SB.

[0086] 32 and 33, the SEP vessel 30B may be stopped so that the bow or stern side on which the crane 33 is mounted is along the side of the floating structure 10. As shown in Fig. 33, the SEP vessel 30B is stopped in a jacked-up state, with the barge body 31 supported in midair above sea level by the lifting legs 32.

[0087] The water depth at which the SEP vessel 30B can be stopped using the lifting legs 32 is approximately 40 m or less. In this construction method, the floating structure 10 is constructed in a sea area with a water depth D1 of 8 m or more and 20 m or less, so the SEP vessel 30B can be stopped in a stable state in the work area A near the floating structure 10.

[0088] Then, using the crane 33 of the SEP vessel 30B moored in the work area A (berthing area SA), a set of assembly parts is installed on the float 2 that has been anchored to the bottom SB of the water in the work area A (bottom landing area BA), and assembly work is performed to assemble an assembly 9 on which the wind power generation device 3 is constructed on the float 2.

[0089] In this embodiment, the assembly 9 is assembled by using the crane 33 of the SEP vessel 30B, which is moored in the first work area A1, to install a set of assembly parts that have been temporarily placed near the first work area A1 on the water structure 10 onto the float 2, which has been anchored to the water bottom SB of the first work area A1.

[0090] Specifically, first, using the crane 33 of the SEP vessel 30B, work is performed to install the divided member 4a that constitutes the base part of the tower 4 that is temporarily placed on the floating structure 10 onto one column 2a of the floating body 2. As illustrated in Figures 34 and 35, the work of installing the divided member 4a uses a tower lift hoisting device 70 and an erection device 73 mounted on a work cart 72.

[0091] The tower lift hoisting device 70 is used as a hoisting device for the crane 33. The tower lift hoisting device 70 is provided with a plurality of clamping portions 70a. The upper end portions of the divided members 4a, which are temporarily placed in a laid-over state (the upper end portions of the divided members 4a when they are installed upright), are clamped by the clamping portions 70a, thereby connecting the tower lift hoisting device 70 to the upper end portions of the divided members 4a.

[0092] The erection device 73 is composed of a holding part 74, a support part 75, and a rotation mechanism 76. The support part 75 is fixed to the loading platform of the work cart 72, and the holding part 74 is supported on the upper part of the support part 75 via the rotation mechanism 76. The holding part 74 is rotatably connected to the support part 75 by the rotation mechanism 76. As illustrated in Figure 34, in the installation work of the divided member 4a, the work cart 72 on which the erection device 73 is mounted is moved near the lower end of the divided member 4a, which is temporarily placed in a laid-down state. Then, the lower part of the divided member 4a is held by the holding part 74.

[0093] Next, as shown by the arrow in Figure 34, the crane 33 lifts the upper end of the divided member 4a via the tower lift hoist 70 toward the raising device 73, and the raising device 73 serves as a guide to rotate the lower end of the divided member 4a, thereby raising the divided member 4a as shown in Figure 35. In this embodiment, while the crane 33 is moving the upper end of the divided member 4a directly above the raising device 73, the rotation of the holding part 74 by the rotation mechanism 76 changes the orientation of the holding part 74. When raising the divided member 4a, it is preferable to hold the weight of the divided member 4a in a suspended state by the crane 33. This reduces the load on the raising device 73 and the work cart 72, allowing for a simple configuration of the raising device 73.

[0094] As shown in Fig. 35, after the separate member 4a has been erected, the erected separate member 4a is hoisted by the crane 33 via the tower lift hoisting device 70 above the erection device 73. Then, as shown in Fig. 36, the crane 33 moves the separate member 4a to above one of the columns 2a of the floating body 2, places the lower end of the separate member 4a on the column 2a, and fixes the lower end of the separate member 4a to the upper end of the column 2a of the floating body 2 by bolting, welding, or the like. Thereafter, the connection of the tower lift hoisting device 70 to the upper end of the separate member 4a is released, and the tower lift hoisting device 70 is separated from the upper end of the separate member 4a.

[0095] Next, similarly, using the crane 33, the tower lift hoist 70, and the erection device 73 mounted on the work platform 72, the divided member 4a constituting the middle part of the tower 4, which is temporarily placed on the floating structure 10, is erected. Then, using the crane 33 and the tower lift hoist 70, the divided member 4a constituting the middle part of the tower 4 is connected to the divided member 4a constituting the base part of the tower 4. Thereafter, similarly, the divided member 4a constituting the upper end part of the tower 4, which is temporarily placed on the floating structure 10, is erected, and the divided member 4a constituting the upper end part of the tower 4 is connected to the divided member 4a constituting the middle part of the tower 4, thereby erecting the tower 4 on the column 2a. Next, using the crane 33, the nacelle hub 5, which is temporarily placed on the floating structure 10, is installed on the top of the tower 4. Thereafter, as illustrated in FIG. 37 , the three blades 6, which are temporarily placed on the floating structure 10, are attached to the nacelle hub 5, respectively, using the crane 33. By carrying out the above operations, the assembly work of the assembly 9 in the first work area A1 is completed.

[0096] Thereafter, in this construction method, as illustrated in FIG. 38 , the SEP vessel 30B is moved sequentially from the work area A where assembly work has been completed to another work area A and stopped there. Then, as illustrated in FIG. 39 , the crane 33 of the SEP vessel 30B is used to perform similar assembly work on the floating body 2 that has been anchored on the bottom SB of that work area A. In parallel with this, additional work, including adjustment work, is performed on the assembly 9 for which assembly work has been completed in advance. The additional work is preparatory work performed on the assembly 9 before transportation to the target sea area for installation, and specifically includes pre-assembly work and pre-commissioning work. The pre-assembly work is work to set up the electrical equipment of the assembly 9. The pre-commissioning work is work to test and adjust the electrical equipment of the assembly 9. In this embodiment, the additional work is performed on the assembly 9 for which assembly work has been completed in the work area A where assembly work has been completed in advance. Additional work on the assembly 9 after the assembly work has been completed may be carried out, for example, by moving the assembly 9 outside the work area A and performing the work in a body of water outside the work area A.

[0097] In this embodiment, before the SEP vessel 30B completes assembly work in the first working area A1, the float 2 is transported by sea to the second working area A2 and the float 2 is placed in a bottom-landing area BA of the second working area A2. After completing assembly work in the first working area A1, the SEP vessel 30B is moved from the mooring area SA of the first working area A1 to the mooring area SA of the second working area A2 and moored there. Then, using the crane 33 of the SEP vessel 30B moored in the second working area A2, a set of assembly parts that have been temporarily placed near the second working area A2 on the floating structure 10 are installed on the float 2 that has been placed on the water bottom SB of the second working area A2, thereby assembling the assembly 9. In parallel with this, in the first work area A1 where assembly work has been completed in advance, pre-assembly work is carried out as additional work on the assembly body 9 for which assembly work has been completed, using a crane 71 or the like placed on the floating structure 10.

[0098] Thereafter, following the same work procedure, as shown in Figure 40, the SEP vessel 30B is moved from the work area A where assembly work has been completed to another work area A and stopped there. Then, using the crane 33 of the SEP vessel 30B, assembly work is performed on the floating body 2 that has settled on the bottom SB of that work area A. In parallel with this, in the work area A where assembly work has been completed earlier, additional work is performed on the assembly body 9 for which assembly work has been completed.

[0099] In this embodiment, before the SEP vessel 30B completes assembly work in the second working area A2, the floater 2 is transported by sea to the third working area A3 and placed in a bottom-landing area BA of the third working area A3. The SEP vessel 30B moves from the mooring area SA of the second working area A2 where assembly work has been completed to the mooring area SA of the third working area A3 and moors there. Then, using the crane 33 of the SEP vessel 30B moored in the third working area A3, a set of assembly parts that have been temporarily placed near the third working area A3 on the floating structure 10 are installed on the floater 2 that has been placed on the bottom SB of the third working area A3, thereby assembling the assembly 9. In parallel with this, in the second working area A2 where assembly work has been completed in advance, pre-assembly work is performed as additional work on the assembly 9 for which assembly work has been completed.

[0100] In the work area A after the pre-assembly work is completed, pre-commissioning work is then performed as additional work on the assembly 9. Then, after the pre-commissioning work has confirmed that there are no abnormalities in the wind turbine generator 3, the assembly 9 is gradually raised from the water bottom SB by reducing the amount of ballast water stored in the floater 2. Then, while the assembly 9 is floating on the sea, it is transported by sea to the target installation area using a tugboat or the like. In this embodiment, while the assembly work is being performed in the third work area A3, additional work (pre-commissioning work) is completed in the first work area A1, and the assembly 9 after the additional work is completed is moved out of the first work area A1 by the time the assembly work is completed in the third work area A3.

[0101] As shown in Figure 1, the assembly 9 after the additional work is completed is transported by sea to the target sea area for installation, where the assembly 9 (float 2) is moored to the seabed SB using mooring lines 7, anchors 8, etc. After that, an underwater cable is connected to the wind turbine 3, and a final operational check (so-called final commissioning) of the floating offshore wind power generation facility 1 is performed. This completes the construction of the floating offshore wind power generation facility 1.

[0102] 41 , in the work area A where the assembly 9 has been transported by sea to the target installation sea area, the newly transported float 2 is settled on the water bottom SB. In this embodiment, by the time the assembly work is completed in the third work area A3, the float 2 is transported by sea to the first work area A1 and is settled in the bottom settlement area BA of the first work area A1.

[0103] Thereafter, using the same work procedure, the SEP vessel 30B is moved from the third work area A3 where assembly work has been completed to the first work area A1 and stopped there, as shown in Figure 41. In this embodiment, the positions of the bottom landing area BA and the mooring area SA are arranged differently between the first and second work operations so that the SEP vessel 30B can be stopped in the first work area A1 at a position close to a set of assembled parts that are temporarily stored near the first work area A1.

[0104] Next, the crane 33 of the SEP vessel 30B parked in the first working area A1 is used to perform assembly work on the floater 2 that has settled on the bottom of the water SB in the first working area A1. In parallel with this, in the third working area A3, where assembly work has been completed in advance, pre-assembly work is performed on the assembled body 9 for which assembly work has been completed. In the second working area A2, where pre-assembly work has been completed, pre-commissioning work is performed, and the assembled body 9, which has been confirmed to have no abnormalities in the wind turbine generator 3, is raised from the bottom of the water SB and transported by sea to the target sea area for installation, where it is moored.

[0105] In this embodiment, before the SEP vessel 30B completes the second assembly work in the first working area A1, the floater 2 is transported by sea to the fourth working area A4 and left in a bottom-landing state in the bottom-landing area BA of the fourth working area A4. Thereafter, following the same work procedure, as illustrated in Figure 42, the SEP vessel 30B moves from the first working area A1 where assembly work has been completed to the fourth working area A4 and stops there. Then, using the crane 33 of the SEP vessel 30B stopped in the fourth working area A4, assembly work is performed on the floater 2 that has landed on the bottom SB of the fourth working area A4. Concurrently, in the first working area A1 where assembly work has been completed in advance, pre-assembly work is performed on the assembled assembly 9. After the pre-assembly work is completed, pre-commissioning work is carried out in the third work area A3, and once it has been confirmed that there are no abnormalities in the wind power generation device 3, the assembly 9 is raised from the bottom SB and transported by sea to the target installation area, where the assembly 9 is moored.

[0106] Thereafter, using the same work procedure, the SEP vessel 30B is moved sequentially from the fourth work area A4 to the fifth work area A5, from the fifth work area A5 to the sixth work area A6, and from the sixth work area A6 to the fourth work area A4, while the assembly work, the addition work, and the assembled body 9 after the addition work are completed are transported by sea to the target installation area and moored, all of which are carried out in parallel in different work areas A, thereby constructing a total of eight floating offshore wind power generation facilities 1.

[0107] When constructing eight or more floating offshore wind power facilities 1, after the assembly work, addition work, and marine transportation work of the assemblies 9 in the first to third work areas A1 to A3 are completed and the SEP vessel 30B and floaters 2 are not positioned in the first to third work areas A1 to A3, a carrier ship carrying assembled parts for the wind power generation devices 3 is stopped in the sea area on the first to third work areas A1 to A3 side of the floating structure 10, and multiple sets of newly assembled parts for the wind power generation devices 3 are temporarily stored. After that, the carrier ship is departed from the floating structure 10, and the floaters 2 are transported by sea to the bottom landing areas BA of the first to third work areas A1 to A3, and the floaters 2 are placed on the water bottom SB of the bottom landing areas BA of each work area A1 to A3.

[0108] Then, after the second assembly work in the fourth working area A4, the SEP vessel 30B is moved from the fourth working area A4 to the first working area A1 and parked there. Then, the crane 33 of the SEP vessel 30B parked in the first working area A1 is used to perform assembly work on the float 2 that has settled on the bottom SB of the first working area A1. Thereafter, the ninth and subsequent floating offshore wind power facilities 1 are constructed in the same manner as the work procedure described above.

[0109] In this way, by simultaneously carrying out the work of temporarily placing the assembly parts of the wind power generation device 3 on the floating structure 10, the assembly work, the addition work, and the work of transporting the assembly 9 after the addition work has been completed by sea to the sea area where it will be installed and mooring it, it is possible to construct a large number of floating offshore wind power generation facilities 1 in parallel.

[0110] When the use of the floating structure 10 as a manufacturing base is finished and the floating structure 10 is to be removed from the sea area, the support piles 11 (top plate 18) and the superstructure panel units 13 are disconnected, and each superstructure panel unit 13 is detached from the support piles 11 and removed using the crane 33 of the SEP vessel 30A or the like. Then, each support pile 11 is extracted from the waterbed ground UG using the crane 33 of the SEP vessel 30A or the like, and the holes in the waterbed ground UG where the support piles 11 were inserted are backfilled, restoring the waterbed ground UG to its state before the floating structure 10 was constructed. The removed support piles 11 and superstructure panel units 13 can be reused when constructing a floating structure 10 in another construction area. In other words, the floating structure 10 can be relocated and reinstalled and removed multiple times in a relatively short period of time.

[0111] As described above, this construction method for the floating offshore wind power facility 1 makes it possible to construct multiple floating offshore wind power facilities 1 in parallel, each with a float 2 having a draft of 20 m or less when moored in the target sea area, and can be adopted for constructing other types of floating offshore wind power facilities 1 except for the spar type. In this construction method, a temporary floating structure 10 is constructed in a relatively shallow sea area with a water depth D1 of 8 m to 20 m, so the cost, labor, and time required to construct the floating structure 10 are relatively low. When a pier 10A is constructed as the floating structure 10 as in this embodiment, the length of the support piles 11 driven into the water bottom SB is relatively short because the sea area is relatively shallow, and the cost, labor, and time required to construct the pier 10A are relatively low. Even when constructing a floating structure as the above-water structure 10, since the sea area is relatively shallow, the work of fixing the mooring equipment that constitutes the floating structure to the bottom SB can be carried out relatively easily, and the cost, effort, and time required to construct the floating structure are relatively low.

[0112] In this construction method, the assembly parts of the wind turbine generator 3 are transported to the floating structure 10 and temporarily stored on the floating structure 10, so there is no need to prepare an installation base for the floating offshore wind power facility 1 such as temporarily storing all the assembly parts together on a quay 90. In other words, preparing an installation base for the floating offshore wind power facility 1 on land requires large-scale construction such as ground improvement work to improve the bearing capacity of the quay 90, which requires relatively much cost, effort, and time, but this construction method does not require such large-scale construction of the quay 90, and there is also no need to secure a large space behind the quay 90. This construction method also has the advantage that it is easy to secure an installation site for the floating structure 10 within a port area because the floating structure 10 is constructed in a sea area with a relatively shallow water depth D1.

[0113] Furthermore, in this construction method, by constructing the floating structure 10 in an ocean area with a water depth D1 of 8 m or more and 20 m or less, it is possible to moor the SEP vessels 30A, 30B near the floating structure 10, and the floating body 2 can be easily landed on the water bottom SB near the floating structure 10. By using the crane 33 of the SEP vessel 30B, which is not affected by waves, and further by landing the floating body 2 on the water bottom SB, the work of assembling the assembly 9 can be carried out efficiently in a very stable state.

[0114] Furthermore, in this construction method, a plurality of work areas A are provided in the sea area adjacent to the floating structure 10, and the SEP vessel 30B that has completed assembly work in any one of the work areas A is moved from the work area A where assembly work has been completed to another work area A, and assembly work is carried out in that work area A, and in parallel with this, additional work including adjustment work is carried out on the assembly 9 for which assembly work has been completed in advance. This allows the assembly work and additional work to be carried out in parallel in separate locations, and enables efficient use of the SEP vessel 30B.

[0115] Generally, additional work takes about one month. For example, if additional work on an assembly 9 for which assembly work has been completed is to be performed in a location other than work area A, a location for the assembly 9 must be secured, and the work of floating the assembly 9 and moving it to another location also requires time and effort. In contrast, with this construction method, additional work on an assembly 9 for which assembly work has been completed can be continued in work area A near the floating structure 10, while assembly work on another assembly 9 can be carried out in parallel in another work area A.

[0116] Furthermore, in sea areas, the period when the working environment is calm and suitable for construction is limited to a certain extent, so if construction is not completed within that suitable period, construction will have to be halted until a suitable period in the following year. Even when constructing a large number of floating offshore wind power facilities 1 under such conditions where the construction period is restricted, this construction method allows for efficient construction without having to secure a space for additional work on the assembly 9 in a quay water area, etc. In other words, this construction method, which can reduce the cycle time for sequentially constructing a large number of floating offshore wind power facilities 1, is extremely advantageous for shortening the overall construction time and building a large number of floating offshore wind power facilities 1.

[0117] After the additional work is completed, the assembly 9 is transported by sea to the target sea area, and construction of the floating offshore wind power facility 1 is completed simply by mooring the assembly 9 in the target sea area. This construction method does not require complicated and advanced work in the target sea area. Therefore, this construction method allows efficient construction of multiple floating offshore wind power facilities 1 in parallel, with the floats 2 having a draft of 20 m or less when moored in the target sea area, without the need to prepare an installation base for the floating offshore wind power facility 1 on a quay 90.

[0118] Furthermore, in this construction method, by providing the floating structure 10 on which the assembly components of the wind turbine generator 3 are temporarily stored, the work of transporting the assembly components can be performed by a carrier vessel other than the SEP vessel 30B. Therefore, there is no need to transport the assembly components of the wind turbine generator 3 by sea using the SEP vessel 30B, and the SEP vessel 30B can be used very efficiently for the assembly work of the assembly body 9. Since the SEP vessel 30B is a specialized vessel and there are only a few of them in Japan, the efficient use of the SEP vessel 30B for the assembly work of the assembly body 9, which can efficiently construct the floating offshore wind power generation facility 1, is a great advantage for those skilled in the art. Furthermore, in this construction method, by providing the floating structure 10, the carrier vessel can quickly move on to the next transportation after temporarily storing the assembly components on the floating structure 10. Therefore, providing the floating structure 10 can also improve the availability of the carrier vessel.

[0119] As in this embodiment, when the SEP vessel 30B is assembling the floating body 2 in another work area A, if additional work on the assembly body 9 is performed in parallel in the work area A where the assembly work has been completed in advance, the additional work can be continued in the work area A where the assembly work has been completed. Also, by performing the additional work in the work area A close to the floating structure 10, the crane 71 and power supply equipment arranged on the floating structure 10 can be used. Therefore, with the above-mentioned configuration, additional work on the assembly body 9 can be performed very efficiently.

[0120] The number of work areas A to be provided for the floating structure 10 can be determined appropriately depending on the number of floating offshore wind power facilities 1 to be constructed and the construction period, but providing six or more work areas A in the sea area adjacent to the floating structure 10 is advantageous for efficiently constructing a large number of floating offshore wind power facilities 1. In particular, when one SEP vessel 30B is used for assembling the assembly 9 as in this embodiment, providing a total of six work areas A, three on each side of the floating structure 10, allows each work area A to be effectively used in parallel, and a large number of floating offshore wind power facilities 1 can be constructed smoothly and efficiently with one SEP vessel 30B.

[0121] The number of sets of assembly parts of the wind turbine power generation device 3 to be temporarily placed on the floating structure 10 can be determined appropriately depending on the number of floating offshore wind power generation facilities 1 to be constructed and the construction period, but constructing an floating structure 10 on which six or more, more preferably eight or more, sets of assembly parts can be temporarily placed is advantageous for efficiently constructing a large number of floating offshore wind power generation facilities 1. In particular, when six work areas A are provided in the sea area adjacent to the floating structure 10, as in this embodiment, constructing an floating structure 10 on which eight sets of assembly parts can be temporarily placed is advantageous for smoothly and efficiently constructing a large number of floating offshore wind power generation facilities 1.

[0122] As in this embodiment, by configuring a new float 2 to land on the bottom of the water SB of the work area A where the assembly 9 has been transported by sea to the target sea area for installation, multiple assemblies 9 can be assembled in one work area A, allowing for very efficient construction of a large number of floating offshore wind power facilities 1. In particular, as in this embodiment, by increasing the number of sets of assembly parts temporarily placed on the floating structure 10 beyond the number of work areas A provided on the floating structure 10, the assembly 9 can be assembled multiple times in one work area A, which is advantageous for efficient construction of a large number of floating offshore wind power facilities 1.

[0123] As in this embodiment, by using a work platform 72 equipped with an erection device 73, the work of erecting the divided members 4a that make up the tower 4 can be performed stably and efficiently. Furthermore, when using a work platform 72 equipped with an erection device 73, the path along which the lower end of the divided member 4a moves is kept constant by the erection device 73 when changing the orientation of the divided member 4a, stabilizing the movement and posture of the divided member 4a. Therefore, the work of erecting the divided members 4a can be performed safely in a very stable state.

[0124] In this construction method, for example, the erection device 73 may be moved by a crane 71 or the like without being mounted on the work platform 72. Furthermore, in this construction method, the erection device 73 and the tower lift hoisting tool 70 may be used as desired, and the installation work of the divided member 4a may also be performed by a different method that does not use the erection device 73 or the tower lift hoisting tool 70.

[0125] In this embodiment, the crane 33 of the SEP vessel 30B is used to directly move the assembled parts temporarily placed on the floating structure 10 to the installation position on the floating body 2, but the assembled parts of the wind turbine generator 3 are large in size and weight. Therefore, depending on the size of the crane 33 of the SEP vessel 30B, it may be difficult to directly move the assembled parts temporarily placed on the floating structure 10 to the installation position on the floating body 2. In such a case, the SEP vessel 30B is stopped so that its side is aligned with the floating structure 10, and the crane 33 of the SEP vessel 30B is used to transfer the assembled parts temporarily placed on the floating structure 10 onto the SEP vessel 30. Then, after changing the orientation of the SEP vessel 30B, the crane 33 may be used to move the assembled parts transferred onto the SEP vessel 30B to the installation position on the floating body 2.

[0126] In this embodiment, when assembling the assembly 9 in each work area A, the orientation of the wind turbine generator 3 relative to the float 2 is exemplified as being the correct orientation for mooring in the sea area where the assembly is to be installed. However, because the blades 6 of the wind turbine generator 3 are huge, if the wind turbine generator 3 is assembled in the correct orientation, the blades 6 may interfere with work in other work areas A. In such a case, it is preferable to assemble the wind turbine generator 3 in such an orientation that the orientation of the tower 4 relative to the float 2 or the orientation of the nacelle hub 5 relative to the tower 4 is shifted from the correct orientation so that the blades 6 of the wind turbine generator 3 do not interfere with work in the other work areas A. Then, after moving the assembly 9 outside the work area A or after moving the assembly 9 to the sea area where the assembly is to be installed, it is preferable to correct the orientation of the tower 4 relative to the float 2 or the orientation of the nacelle hub 5 relative to the tower 4 to the correct orientation.

[0127] While this embodiment illustrates the use of one SEP vessel 30B for the assembly work of the assembly 9, it is also possible to use two or more SEP vessels 30B to construct the floating offshore wind power facility 1. For example, when two SEP vessels 30B are used, one SEP vessel 30B is moved sequentially through work areas A (first to third work areas A1 to A3) in the sea area on one side of the floating structure 10 to perform the assembly work of the assembly 9, and the other SEP vessel 30B is moved sequentially through work areas A (fourth to sixth work areas A4 to A6) in the sea area on the other side of the floating structure 10 to perform the assembly work of the assembly 9. In this way, using two or more SEP vessels 30B is advantageous for constructing a large number of floating offshore wind power facilities 1 in a shorter construction period.

[0128] As in this embodiment, when constructing an abovewater structure 10, in the pile driving operation, a driving guide jig 40 having multiple pile insertion sections 41 arranged at intervals (L1, L2) from each other in a plan view is placed on the water bottom ground UG, and multiple support piles 11 are driven into the water bottom ground UG using the pile insertion sections 41 as guides, so that the support piles 11 can be driven while the horizontal movement of the support piles 11 is restricted by the pile insertion sections 41. Therefore, by utilizing the multiple pile insertion sections 41 of the driving guide jig 40, the multiple support piles 11 can be driven with precision in a pre-planned arrangement.

[0129] Furthermore, in the superstructure construction work, if an superstructure panel unit 13 is prepared in advance, which has a floor structure 14 extending across multiple support piles 11 and multiple support girders 17 arranged at an interval (L1) from each other in a plan view below the floor structure 14, then in the construction water area, each support girder 17 that makes up the superstructure panel unit 13 can be erected on top of multiple support piles 11, and the superstructure panel unit 13 can be fixed to the top of the multiple support piles 11 to construct a superstructure 12 extending across multiple support piles 11.

[0130] The use of the driving guide jig 40 allows multiple support piles 11 to be driven accurately in a pre-planned arrangement, preventing misalignment between the support girders 17 that make up the pre-fabricated superstructure panel units 13 and the support piles 11. This reduces the number of man-hours required to construct the floating structure 10 in the construction waters, allowing the floating structure 10 to be constructed efficiently. The construction method for the floating structure 10 of this embodiment eliminates the need for steel frame assembly work or diving work at the water's edge in the construction waters, making it possible to construct and remove the floating structure 10 in a short period of time. Furthermore, it also makes it possible to reuse (reuse) the components that make up the floating structure 10 multiple times.

[0131] Furthermore, as in this embodiment, when the support piles 11 are driven with the support piles 11 inserted through the pile insertion portions 41 of the driving guide jig 40, it is possible to prevent the support piles 11 from being driven in an inclined state or from wobbling during driving. Therefore, even when the waterbed ground UG is relatively soft, the support piles 11 can be driven with precision in the correct orientation. This is very advantageous in preventing misalignment between the support girders 17 that make up the prefabricated superstructure panel unit 13 and the heads of the support piles 11 driven into the waterbed ground UG.

[0132] As in this embodiment, in pile driving work, if the SEP vessel 30A is stopped in a jacked-up state and the support piles 11 are driven into the waterbed ground UG using a pile driving device 34 suspended by a crane 33, the pile driving work can be carried out efficiently in a stable state free from the influence of waves. Furthermore, in superstructure construction work, if the superstructure panel units 13 placed on the barge body 31 of the SEP vessel 30A are installed on top of the multiple support piles 11 using the crane 33, the superstructure construction work can be carried out efficiently in a stable state free from the influence of waves.

[0133] As in this embodiment, in the reference pile driving step in pile driving work, the SEP vessel 30A is stopped in a jacked-up state, and the pile guide section 51 of the driving auxiliary device 50 mounted on the barge body 31 of the SEP vessel 30A is positioned outside the barge body 31. Then, when the support pile 11 serving as the positioning reference is inserted into the pile guide section 51 and driven into the waterbed ground UG, the support pile 11 serving as the positioning reference can be driven efficiently and accurately to the pre-planned driving position. In the post-driving step following the reference pile driving step in pile driving work, the driving guide jig 40 is lowered from above the support pile 11 serving as the positioning reference, and the driving guide jig 40 is positioned on the waterbed ground UG with the support pile 11 serving as the positioning reference inserted into one of the pile insertion sections 41. Then, by using the other pile insertion portions 41 into which the support pile 11 serving as the positioning reference has not been inserted as guides, the support piles 11 other than the support pile 11 serving as the positioning reference are driven at intervals (L1, L2) from each other in a plan view, and the support piles 11 other than the support pile 11 serving as the positioning reference can also be driven with precision in a pre-planned arrangement.

[0134] Furthermore, as in this embodiment, in the reference pile driving step, a plurality of support piles 11 that serve as positioning references are driven using the driving auxiliary device 50. Then, in the post-driving step, if the driving guide jig 40 is placed on the water bottom ground UG with the support piles 11 that serve as positioning references inserted into two or more pile insertion portions 41, respectively, the driving guide jig 40 does not rotate horizontally during the process of placing the driving guide jig 40 on the water bottom ground UG, and the pile insertion portions 41 that do not have support piles 11 inserted therein can be easily and accurately positioned at the pre-planned driving positions of the support piles 11.

[0135] When constructing the abovewater structure 10, for example, one support pile 11 serving as a positioning reference can be driven, and the second support pile 11 can be driven with the support pile 11 serving as a positioning reference inserted into one pile insertion portion 41 constituting the driving guide jig 40. In this case, since there is a possibility that the driving guide jig 40 will rotate horizontally during the process of placing the driving guide jig 40 on the water bottom ground UG, it is preferable to configure the driving guide jig 40 to be guided by an ROV, seabed visual sonar, or the like so that the pile insertion portion 41 through which the support pile 11 is not inserted is positioned at the pre-planned driving position for the support pile 11.

[0136] When constructing the floating structure 10, for example, the support piles 11 serving as the positioning reference can be driven using the driving auxiliary device 50 and the driving guide jig 40. In this case, the driving guide jig 40 is placed on the bottom ground UG, and the support piles 11 serving as the positioning reference are driven with the pile guide portion 51 of the driving auxiliary device 50 and the pile insertion portion 41 of the driving guide jig 40. In this case, the support piles 11 serving as the positioning reference can be driven with precision at the pre-planned driving positions of the support piles 11. However, by using only either the driving auxiliary device 50 or the driving guide jig 40, the support piles 11 serving as the positioning reference can be driven with precision at the pre-planned driving positions of the support piles 11. Therefore, when using the driving auxiliary device 50 in the reference pile driving process, it is preferable to perform the reference pile driving process using only the driving auxiliary device 50, without using the driving guide jig 40, within the reach of the driving auxiliary device 50. It is then advisable to use the casting guide jig 40 in the post-casting process.

[0137] As in this embodiment, when a casting guide jig 40 is used in which the pile insertion portions 41 are arranged in two rows in the front-to-back direction when viewed from above and in three rows in the left-to-right direction, the size of the casting guide jig 40 does not become excessive, and it becomes easier to align each pile insertion portion 41 of the casting guide jig 40 with the support piles 11 cast into the bottom ground UG.

[0138] If an I-beam having a height of 700 mm to 2000 mm and a width of 300 mm to 800 mm is used as the support girder 17 constituting the superstructure panel unit 13, the load-bearing capacity of the support girder 17 can be made higher than when an H-beam is used as the support girder 17, and therefore the spacing (L2) between the support piles 11 on which the support girders 17 are erected can be set to a very long span of, for example, 10 m to 30 m. Therefore, using an I-beam that satisfies the above-mentioned dimensional conditions as the support girder 17 is advantageous in reducing the number of support piles 11 constituting the floating structure 10 and the number of members constituting the floating structure panel unit 13, and is advantageous in reducing the number of work steps and construction costs required to construct the floating structure 10.

[0139] As in this embodiment, it is preferable to use superstructure panel units 13 that extend across a total of nine support piles 11, three rows in each of the X and Y directions, but it is also possible to use superstructure panel units 13 that extend across four or more rows of support piles 11 in at least either the X or Y direction. It is also possible to use superstructure panel units 13 that extend across two rows of support piles 11 in at least either the X or Y direction.

[0140] When constructing the floating structure 10, the number and arrangement of the support piles 11 and superstructure panel units 13 loaded on the SEP vessel 30A are not limited to those in the above-described embodiment, and can be determined appropriately depending on the sizes of the SEP vessel 30A, the support piles 11, and the superstructure panel units 13. As in the above-described embodiment, it is preferable to use the SEP vessel 30A in the work of constructing the floating structure 10, but it is also possible to perform pile driving work and superstructure construction work using, for example, a crane vessel other than the SEP vessel 30A. Furthermore, when constructing the floating structure 10 near an existing floating structure or a quay 90, it is also possible to perform pile driving work and superstructure construction work using a crane arranged on the existing floating structure or quay 90.

[0141] In the above-described embodiment, an example is given of constructing an above-water structure 10 that is rectangular in shape when viewed from above, but it is also possible to construct an above-water structure 10 that is other planar shapes, such as an L-shape or a cross shape when viewed from above. The number and arrangement of the support piles 11 that constitute the above-water structure 10 are not limited to the above-described embodiment, and various other configurations are possible. Furthermore, the positions and number of the support piles 11 that serve as positioning references, the order in which the support piles 11 are driven, and the like are not limited to the above-described embodiment, and can be determined appropriately depending on the number and arrangement of the support piles 11 that constitute the above-water structure 10.

[0142] The floating structure 10 can also be configured as shown in Figure 43. The floating structure 10 of the embodiment shown in Figure 43 is configured so that one support girder 17 constituting the superstructure 12 is installed for each support pile 11. Specifically, when a support girder 17 is installed at the other end (e.g., right end) of one superstructure panel unit 13 (e.g., left side) installed adjacent to each other in the X direction, no support girder 17 is installed at one end (e.g., left end) of the other superstructure panel unit 13 (e.g., right side). Even with this configuration, a stable floating structure 10 can be constructed by placing the floor structure 14 (girders 15) constituting the other superstructure panel unit 13 on the support girder 17 installed at the other end of the one superstructure panel unit 13.

[0143] In the embodiment illustrated in Figure 44, the offshore structure 10 is configured as a floating structure 10B.

[0144] When the floating structure 10 is constructed as a floating structure 10B, for example, the assembly parts of the wind turbine generator 3 are placed in advance on a float that forms the top plate of the floating structure 10B, and the float with the assembly parts placed on it is towed to the construction area where the floating structure 10 is to be constructed. Then, the float with the assembly parts of the wind turbine generator 3 temporarily placed on it is fixed on mooring equipment that is fixed to the seabed SB of the construction area. This eliminates the need to transport the assembly parts of the wind turbine generator 3 by a carrier ship or the like after the floating structure 10 is constructed, allowing the floating offshore wind power facility 1 to be constructed very efficiently. Note that when the floating structure 10 is constructed as a floating structure 10B, as in the case of constructing the pier 10A, the assembly parts of the wind turbine generator 3 can be transported by a carrier ship or the like after the floating structure 10B is constructed in the sea area, and the assembly parts can be temporarily placed on the floating structure 10B.

[0145] Although the above example illustrates the construction of a semi-submersible floating offshore wind power facility 1, the same construction method and effect can be achieved when constructing a TLP type floating offshore wind power facility 1 or a barge type floating offshore wind power facility 1. The present invention can also be used when constructing multiple types of floating offshore wind power facilities 1 in parallel.

[0146] The floating structure 10 can be constructed in an ocean area with a water depth of 8 m to 20 m and can temporarily store multiple wind power generation device 3 assemblies. The shape and structure of the floating structure 10, as well as the method of constructing the floating structure 10, are not limited to the configurations exemplified in the above-mentioned embodiments, and various other configurations are possible.

[0147] REFERENCE SIGNS LIST 1 Floating offshore wind power generation facility 2 Floating body 2a Column 2b Connector 3 Wind power generation device 4 Tower 4a Divided member 5 Nacelle hub 6 Blade 7 Mooring line 8 Anchor 9 Assembly 10 Water structure 10A Pier 10B Floating structure 11 Support pile 12 Superstructure 13 Superstructure panel unit 14 Floor structure 15 Girder 16 Deck 16a Covering plate 17 Support girder 18 Top plate 19 Support member 20 Mooring equipment 21 Shock prevention equipment 30, 30A, 30B Self-elevating barge (SEP vessel) 31 Barge body 32 Lifting leg 33 (Mounted on the self-elevating barge) Crane 33a Wire rope 34 Pile driving device 40 1. Pouring guide jig 41 Pile insertion section 42 Enlarged head section 43 Enlarged bottom section 44 Subsidence suppression section 45 Connecting section 46 Lifting device 47 Receiving device 50 Pouring auxiliary device 51 Pile guide section 51a Opening / closing section 51b Switching mechanism 52 Moving mechanism 53 First moving mechanism 54 Actuator 54a Cylinder 54b Rod 55 Second moving mechanism 56 Rotating section 57 Lifting section 58 Support section 59 Lifting guide 60 Third moving mechanism 61 Rail for moving in the longitudinal direction of the ship 62 Movable platform 70 Tower lift hoisting device 70a Clamping section 71 Crane (disposed on the floating structure) 72 Work cart 73 Elevating device 74 Holding section 75 Support section 76 Rotating mechanism 80 Breakwater 90 Quay SB Bottom of the water UG Bottom ground WL Water surface position A, A1 to A6 (1st to 6th) Working area BA Bottom landing area SA Mooring area RW Traveling path

Claims

1. A construction method for constructing multiple floating offshore wind power generation facilities in parallel, each of which has a float moored in a target sea area and a wind power generation device erected on the float, with the float moored in the target sea area and the draft from the water surface to the bottom end of the float being 20m or less, comprising the steps of: constructing a temporary floating structure in a sea area with a water depth of 8m to 20m; setting up multiple work areas in the sea area adjacent to the floating structure; temporarily placing multiple sets of assembly parts for the nacelle hub, blades and tower that make up the wind power generation device on the floating structure; a self-elevating barge having lifting legs, a barge body capable of rising and lowering relative to the lifting legs, and a crane mounted on the barge body is parked in a jacked-up state with the lifting legs of the self-elevating barge anchored on the bottom of the water in any of the work areas, and an assembly work is performed by using the crane of the self-elevating barge to install a set of assembly parts temporarily placed on the water structure onto the floating body anchored on the bottom of the work area, and assembling an assembly in which the wind power generation device is constructed on the floating body; the self-elevating barge is moved sequentially from the work area where the assembly work has been completed to another work area, and the assembly work is performed on the floating body anchored on the bottom of the work area, and in parallel with this, additional work including adjustment work is performed on the assembly for which the assembly work has been completed in advance; A construction method for a floating offshore wind power facility, characterized in that the assemblies after the additional work are completed are sequentially transported by sea to the target sea area for installation, and the assemblies are moored in the target sea area for installation.

2. A construction method for a floating offshore wind power facility as described in claim 1, comprising the steps of: temporarily placing the tower partition members in a laid-sideways position on the floating structure; using the crane and a raising device arranged on the floating structure to raise the previously laid-sideways former partition members; and installing the raised partition members on the float using the crane.

3. A construction method for a floating offshore wind power facility as described in claim 1 or 2, wherein while the assembly work is being performed on the float in the other work area by the self-elevating barge, additional work is performed on the assembly in the work area where the assembly work has been previously completed in parallel.

4. A construction method for a floating offshore wind power facility as described in any one of claims 1 to 3, in which a new float is landed on the bottom of the work area after the assembly is transported by sea to the target sea area for installation.

5. A construction method for a floating offshore wind power facility as described in any one of claims 1 to 4, in which six or more work areas are provided in the sea area adjacent to the floating structure.

6. The above-water structure is constructed by integrating the multiple support piles and the superstructure by carrying out pile driving work to erect multiple support piles on the water bottom and superstructure construction work to build a superstructure on top of the multiple support piles, and in the pile driving work, a driving guide jig having multiple pile insertion portions arranged at intervals from each other in a planar view is placed on the water bottom, and the multiple support piles are driven into the water bottom at intervals from each other in a planar view using the pile insertion portions as guides, A construction method for a floating offshore wind power facility as described in any one of claims 1 to 5, in which, in the superstructure construction work, a superstructure panel unit having a floor structure extending across a plurality of the support piles and a plurality of support girders arranged at intervals from each other in a planar view at the bottom of the floor structure is prepared in advance, and each of the support girders that constitute the superstructure panel unit is erected on top of the plurality of support piles, and the superstructure is constructed by fixing the superstructure panel unit to the tops of the plurality of support piles.

7. A construction method for a floating offshore wind power facility as described in claim 6, wherein, in the pile driving work, the self-elevating barge or a self-elevating barge other than the self-elevating barge is stopped in the jacked-up state, and the support piles are driven into the waterbed using a pile driving device suspended by a crane of the self-elevating barge, and, in the superstructure construction work, the superstructure panel units placed on the barge body are installed on the tops of a plurality of the support piles using the crane of the self-elevating barge.

8. The above-water structure is constructed by integrating the above-water structure with the above-water structure by carrying out pile driving work to erect a plurality of support piles on the water bottom ground and superstructure construction work to construct a superstructure on the top of the above-mentioned plurality of support piles, and in the reference pile driving process to drive the support pile that will be used as a reference for positioning in the pile driving work, the self-elevating barge or a self-elevating barge other than the self-elevating barge is stopped in the jacked-up state, a driving auxiliary device is mounted on the barge body, the driving auxiliary device includes a pile guide section through which the support pile is inserted and a moving mechanism for moving the pile guide section relative to the barge body, the pile guide section is positioned outside the barge body by the moving mechanism, and the support pile that will be used as a reference for positioning is inserted into the pile guide section and driven into the water bottom ground, In the post-driving process of driving the other support piles subsequent to the reference pile driving process in the pile driving work, the self-elevating barge is stopped in the jacked-up state, a driving guide jig having a plurality of pile insertion portions arranged at intervals from each other in a planar view is lowered from above the support pile that is to be used as a reference for positioning, and the driving guide jig is placed on the water bottom ground with the support pile that is to be used as a reference for positioning inserted into any of the pile insertion portions, and the other pile insertion portions into which the support pile that is to be used as the reference for positioning is not inserted are used as guides to drive the support piles other than the support pile that is to be used as the reference for positioning at intervals from each other in a planar view, A construction method for a floating offshore wind power facility as described in any one of claims 1 to 5, wherein, in the superstructure construction work, a superstructure panel unit having a floor structure extending across a plurality of the support piles and a plurality of support girders arranged at intervals from each other in a planar view below the floor structure is prepared in advance and placed on the barge body of the self-elevating barge. The superstructure panel unit is then placed on the plurality of support piles that have been driven into the waterbed using a crane of the self-elevating barge, so that each of the support girders that constitute the superstructure panel unit is erected on the plurality of support piles, and the superstructure is constructed by fixing the superstructure panel unit to the tops of the plurality of support piles.

9. A construction method for a floating offshore wind power facility as described in claim 8, wherein, in the reference pile driving step, the driving auxiliary device is used to drive a plurality of support piles that serve as a reference for positioning, and, in the post-driving step, the driving guide jig is placed on the water bottom ground with the support piles that serve as a reference for positioning inserted into two or more pile insertion portions.

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