Construction method for spar-type offshore wind power generation facility

Abstract

To safely and stably construct a spar-type offshore wind power generation facility.SOLUTION: A construction method for a spar-type offshore wind power generation facility includes: a first step of installing a crane facility for construction 30 provided with a tower crane 32 and a floating body gripper mechanism 34 on the ocean; a second step of floating a concrete ring unit 11 with a plurality of tiers of concrete rings 15 assembled from a bottom most tier side and retaining the concrete ring unit 11 by a floating body gripper mechanism 34; a third step of completing a concrete floating body unit 4A by a procedure for integration by stacking up the concrete rings 15 on top of the concrete ring unit 11 in order by using the tower crane 32 as well as integrating by binding with PC steel 19; a fourth step of completing the floating body 4 by coupling a steel floating unit 4B to topside of the concrete floating unit 4A; and a fifth step of loading a tower 6 on top of the floating body 4 and furthermore completing a spar type offshore wind power generation facility 1 by further attaching a nacelle 8 and a blade 9.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a method for constructing a spar-type offshore wind power generation facility equipped with a spar-type float consisting of a concrete floating body section formed by stacking concrete rings in a plurality of tiers and fastening each concrete ring to an integrated body with prestressing steel members, and a steel floating body section connected to the upper side of the concrete floating body section; or a spar-type float consisting of a concrete float formed by stacking concrete rings in a plurality of tiers and fastening each concrete ring to an integrated body with prestressing steel members. [Background technology]

[0002] Traditionally, hydroelectric, thermal and nuclear power generation have been the main power generation methods used, but in recent years, wind power generation, which uses natural wind to generate electricity, has been attracting attention from the perspective of the environment and the effective use of natural energy. Wind power generation facilities can be installed on land or on water (mainly offshore), but in Japan, which has mountainous terrain behind its coasts, there are few plains in coastal areas where stable winds can be expected. On the other hand, Japan is surrounded by sea on all sides, and has the advantage that winds suitable for generating electricity can be easily obtained on the sea and there are fewer restrictions on installation. For this reason, many different types of offshore wind power generation facilities and floating structures have been proposed in recent years.

[0003] The floating structure can be broadly classified into purge type floats, which float on the water surface, semi-submersible floats, which have the lower part of the float submerged below the water surface, and spar type floats in an upright position like a fishing float.

[0004] With regard to the spar-type float, the applicant has proposed in Patent Document 1 listed below an offshore wind power generation facility consisting of a float, mooring lines, a tower, and a nacelle and multiple wind turbine blades installed at the top of the tower, wherein the float is an offshore wind power generation facility with a spar-type floating structure consisting of a lower concrete floating structure part (hereinafter referred to as the concrete floating structure part) in which concrete precast cylindrical bodies are stacked vertically in multiple tiers and each precast cylindrical body is fastened and integrated with PC steel members, and an upper steel floating structure part (hereinafter referred to as the steel floating structure part) connected to the upper side of this lower concrete floating structure part (hereinafter referred to as the steel floating structure part).

[0005] Then, in 2016, they began commercializing a hybrid spar-type floating offshore wind power generation facility off the coast of Sakiyama, Goto City, Nagasaki Prefecture. The facility is 172 meters long, weighs 3,400 tons, and has a generating capacity of 2 megawatts.

[0006] As shown in Fig. 26, the method of constructing the float of the spar-type offshore wind power generation facility is as follows: in a shipyard, the steel floating part is divided into steel rings of a predetermined weight, and then these steel rings are connected by welding to complete the steel floating part. Then, the steel floating part is loaded onto a barge and transported to a local fabrication yard, where it is unloaded (landed) at a quay using a large crane ship of 1300t class. Meanwhile, the concrete floating part is manufactured in a concrete manufacturer's factory in a state where each ring is divided into several parts in the circumferential direction for the convenience of truck transportation, and these divided rings are transported by truck to the local fabrication yard, where they are connected in the circumferential direction, and then each ring is connected in the longitudinal direction using PC steel to complete the concrete floating part. Finally, the steel floating part and the concrete floating part are connected using a large crane ship of 1300t class to complete the float. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 5274329 [Patent Document 2] Patent No. 6108445 [Patent Document 3] JP 2022-33554 A [Patent Document 4] JP 2012-201219 A [Patent Document 5] JP 2022-55468 A Summary of the Invention [Problem to be solved by the invention]

[0008] In the case of the above-mentioned method for constructing a spar-type float, the float is constructed by connecting the concrete rings in order with the concrete floating body part laid horizontally, but there is a problem that the concrete rings are easily cracked due to the weight of the concrete, and that the concrete rings may be cracked due to an excessive load acting on them during assembly work, transportation work, and erection of the float. In order to deal with such problems, the applicant proposed in the above-mentioned Patent Document 2 that the concrete rings are reinforced by winding an outer cable with tension introduced therein in the circumferential direction around the outer circumferential surface of each precast cylindrical body (concrete ring), and further proposed in the above-mentioned Patent Document 3 that the reinforcement is performed by stretching tension cables 61, 61 ... along the inscribed regular polygon line inside the cylindrical precast concrete member 60 (concrete ring) as shown in Fig. 27.

[0009] Furthermore, when constructing at sea, it is desirable to install wind turbine equipment such as the tower, nacelle, and blades while the spar-type float is floating on the sea, and this should be done in a bay with calm waves. However, while the draft (part below the water surface) of the spar-type float is deep, at approximately 70 m or more, the water depth in a bay is generally shallower than this, making construction in the bay difficult. As such, when installing the wind turbine equipment, as shown in Patent Document 4 above, it has been customary to use a large crane ship outside the bay where the water is deep.

[0010] However, at present, there are only a few large crane ships in Japan that are capable of constructing offshore wind power generation facilities, and the daily usage fee (charter fee) is more than 10 million yen, which poses the problem of huge charter costs.Therefore, in the above-mentioned Patent Document 5, the applicant proposed a wind turbine mounting method in which a tower is attached to a float that is the same as the float of the offshore wind power generation facility to be installed on the sea, and a crane-mounted float with crane equipment on top of the tower is used to mount a wind turbine on the tower of the offshore wind power generation facility to be installed on the sea.

[0011] This method makes it possible to install wind turbine equipment such as nacelles without chartering a large crane ship, but there are problems with this type of crane-mounted floater, as it is prone to rocking on the ocean and has low stability, and a high degree of precision is required to align it with the object to be installed when erecting it.In addition, as offshore wind power generation facilities continue to grow in size, there is a strong demand for a method that allows for the safe and stable construction of spar-type offshore wind power generation facilities in open ocean areas that are subject to the effects of waves outside the bay.

[0012] Therefore, the main object of the present invention is to provide a method for constructing a spar-type offshore wind power generation facility that enables the construction of a float without reinforcing the concrete ring float, and enables the construction of a spar-type offshore wind power generation facility to be carried out safely and stably even at sea without using a large crane ship. [Means for solving the problem]

[0013] In order to solve the above problems, the present invention according to claim 1 provides a method for constructing a spar-type offshore wind power generation facility, which includes a spar-type floater including a concrete floating body section in which concrete rings are stacked in a plurality of stages and each concrete ring is fastened and integrated with a PC steel member, and a steel floating body section connected to the upper side of the concrete floating body section, A first step of mounting a tower crane on a base float and installing a construction crane facility on the sea, the construction crane facility having a plurality of float gripper mechanisms for holding the spar-type float under construction on the side of the base float; A second step of floating a concrete ring unit formed by assembling multiple concrete rings from the bottom side on the sea and holding the concrete ring unit by the floating gripper mechanism; a third step of stacking concrete rings in sequence on the upper side of the concrete ring unit using the tower crane and fastening them with prestressing steel members to complete a concrete floating body; a fourth step of connecting the steel floating body section to the upper side of the concrete floating body section using the tower crane to complete the floating body; There is provided a method for constructing a spar-type offshore wind power generation facility, characterized by comprising a fifth step of using the tower crane to mount a tower on top of the float, and then attaching a nacelle and blades to complete the spar-type offshore wind power generation facility.

[0014] In the invention described in claim 1 above, while conventionally the float assembly work was carried out in a horizontal position on land, this invention changes the idea and assembles the float while it is floating on the sea. As a result, since the assembly is carried out while it is floating on the sea, there is no need to reinforce the concrete rings, and since no extra load is applied to the concrete rings, it is possible to prevent cracks and damage. In addition, since the float is floating vertically when all the float components have been assembled, there is no need to erect the float, which makes it possible to improve the efficiency of the assembly work.

[0015] The specific construction method is as follows: first, a tower crane is mounted on a base float, and a construction crane facility having a plurality of float gripper mechanisms for holding the spar-type float under construction on the side of the base float is installed on the sea (first step). A purged or semi-submersible float is usually used as the base float, and serves as a buoyant structure supporting the tower crane on the sea.

[0016] Next, a concrete ring unit assembled from multiple tiers of concrete rings starting from the bottom tier is floated on the sea and held by the floating gripper mechanism (second step). The concrete ring unit is a concrete ring portion assembled in multiple tiers to be floated on the sea, and once it is initially floated on the sea, it is held by the floating gripper mechanism of the construction crane equipment to prevent it from moving. The number of tiers of the concrete ring unit is the number required to float on the sea by buoyancy.

[0017] Next, the concrete rings are stacked in order on top of the concrete ring unit using the tower crane, and the concrete rings are fastened together with prestressing steel bars to complete the concrete floating section (third step). In other words, while the concrete ring unit is left floating on the sea, the remaining concrete is assembled to complete the concrete floating section.

[0018] In the next step, the tower crane is used to connect the steel floating section to the upper side of the concrete floating section to complete the float (fourth step). The steel floating section is fabricated on land in advance, transported to the construction site by a transport barge, and constructed all at once using the tower crane.

[0019] Finally, the tower crane is used to mount a tower on top of the float, and then the nacelle and blades are attached to complete the spar-type offshore wind power generation facility (fifth step).

[0020] The crane used in the present invention is a construction crane facility with a tower crane mounted on a base float, so it is less prone to shaking and more stable offshore than the spar type, making it easier to align with the installation target during erection. In addition, the stability is increased by the float being held by the float gripper mechanism, so that a spar type offshore wind power generation facility can be stably constructed even offshore.

[0021] The present invention according to claim 2 provides a method for constructing a spar-type offshore wind power generation facility having a spar-type floater including a concrete floating body section formed by stacking concrete rings in a plurality of stages and fastening each concrete ring to an integrated body with prestressing steel members, and a steel floating body section connected to the upper side of the concrete floating body section, comprising: A first step of mounting a tower crane on a base float and installing a construction crane facility on the sea, the construction crane facility having a plurality of float gripper mechanisms for holding the spar-type float under construction on the side of the base float; A second step of assembling the entire float on the wharf, transporting the completed float to a construction site of the spar-type offshore wind power generation facility by a semi-submersible spud barge, and holding the float by the float gripper mechanism once the float has been floated offshore; There is provided a method for constructing a spar-type offshore wind power generation facility, characterized by comprising a third step of using the tower crane to mount a tower on top of the float, and then attaching a nacelle and blades to complete the spar-type offshore wind power generation facility.

[0022] The invention described in claim 2 above shows a construction method in which the float is constructed all at once. Specifically, after the float is completed on the quay and transported to the construction site by a semi-submersible spud barge, the float is floated off into the ocean and held by the float gripper mechanism (second step). Next, a tower is mounted on the top of the float using the tower crane, and a nacelle and blades are attached to complete the spar-type offshore wind power generation facility (third step). In the case of the present invention, the use of a semi-submersible spud barge is assumed, but there is no need to reinforce the concrete ring, and since no extra load is applied to the concrete ring, it is possible to prevent cracks and damage. In addition, by floating off the semi-submersible spud barge and injecting ballast water, the float can be floated on the ocean in an erected state, which makes it possible to improve the efficiency of the assembly work.

[0023] The present invention according to claim 3 provides a method for constructing a spar-type offshore wind power generation facility having a spar-type float made of concrete, the spar-type float being made of concrete floats stacked in a plurality of tiers and each concrete ring being fastened and integrated with a PC steel member, comprising: A first step of mounting a tower crane on a base float and installing a construction crane facility on the sea, the construction crane facility having a plurality of float gripper mechanisms for holding the spar-type float under construction on the side of the base float; A second step of floating a concrete ring unit formed by assembling multiple concrete rings from the bottom side on the sea and holding the concrete ring unit by the floating gripper mechanism; a third step of stacking concrete rings in sequence on the upper side of the concrete ring unit using the tower crane and fastening them with PC steel members to complete a concrete floating body; The present invention provides a method for constructing a spar-type offshore wind power generation facility, comprising a fourth step of using the tower crane to mount a tower on top of the concrete float, and then attaching a nacelle and blades to complete the spar-type offshore wind power generation facility.

[0024] The invention described in claim 3 above shows a construction method for a concrete float in which the entire float is made of concrete. Basically, after completing the float in steps 1 to 3 of the invention described in claim 1, the offshore wind power generation facility can be completed by attaching the tower, nacelle, and blades in step 4.

[0025] The present invention according to claim 4 provides a method for constructing a spar-type offshore wind power generation facility having a spar-type float made of concrete, the spar-type float being made of concrete floats stacked in a plurality of tiers and each concrete ring being fastened and integrated with prestressing steel members, comprising: A first step of mounting a tower crane on a base float and installing a construction crane facility on the sea, the construction crane facility having a plurality of float gripper mechanisms for holding the spar-type float under construction on the side of the base float; A second step of assembling the entire float on the wharf, transporting the completed float to a construction site of the spar-type offshore wind power generation facility by a semi-submersible spud barge, and holding the float by the float gripper mechanism once the float has been floated offshore; There is provided a method for constructing a spar-type offshore wind power generation facility, characterized by comprising a third step of using the tower crane to mount a tower on top of the float, and then attaching a nacelle and blades to complete the spar-type offshore wind power generation facility.

[0026] The invention described in claim 4 above shows a method for constructing a concrete floating body that is entirely made of concrete. The specific construction procedure is exactly the same as the invention described in claim 2 above.

[0027] The present invention according to claim 5 provides a method for constructing a spar-type offshore wind power generation facility according to any one of claims 1 to 4, in which ballast is injected into or discharged from the float at any time during each step to adjust the draft.

[0028] The invention described in claim 5 above is adapted to constantly stabilize the incomplete floating body by injecting or discharging ballast into or from the floating body at any time during each step.

[0029] The present invention according to claim 6 provides a method for constructing a spar-type offshore wind power generation facility according to any one of claims 1 to 4, in which stability is improved by interconnecting the floats during their construction or after their completion.

[0030] In the invention described in claim 6 above, the stability of the construction crane equipment can be improved by connecting the floats held by the float gripper mechanism to each other during construction of the floats or after completion of the floats.

[0031] The present invention as claimed in claim 7 provides a method for constructing a spar-type offshore wind power generation facility as described in any one of claims 1 to 4, in which mooring ropes are installed on each float during construction of the float or after completion of the float to improve stability.

[0032] In the invention described in claim 7 above, the stability of the construction crane equipment can be improved by providing mooring lines to each float held by the float gripper mechanism during construction of the float or after completion of the float.

[0033] The present invention according to claim 8 provides a method for constructing a spar-type offshore wind power generation facility as described in any one of claims 1 to 4, in which an auxiliary construction crane facility having a tower crane installed on the upper surface of the base floating body is installed adjacent to the construction crane facility separately from the construction crane facility.

[0034] In the invention described in claim 8 above, in addition to the construction crane equipment, an auxiliary construction crane equipment consisting of a tower crane installed on the top surface of the base float is installed in an adjacent position, so that the float, tower, nacelle and blades can be assembled by using the two tower cranes in cooperation (co-hoisting work). Effect of the Invention

[0035] As explained above in detail, according to the present invention, it becomes possible to construct a float without reinforcing the concrete ring float, and it becomes possible to construct a spar-type offshore wind power generation facility safely and stably even at sea without using a large crane ship. [Brief description of the drawings]

[0036] [Figure 1] FIG. 1 is an overall view of a spar-type floating offshore wind power generation facility 1. [Diagram 2] FIG. [Diagram 3] 1 shows a precast cylindrical body 15, in which (A) is a longitudinal cross-sectional view, (B) is a plan view (viewed in the direction of the arrow BB), and (C) is a bottom view (viewed in the direction of the arrow CC). [Figure 4] 1A and 1B are diagrams showing how precast cylindrical bodies 15 are fastened together. [Diagram 5]1 is an enlarged vertical cross-sectional view showing the boundary between a concrete floating body portion 4A and a steel floating body portion 4B. [Figure 6] FIG. 2 is a side view of construction crane equipment 30. [Figure 7] FIG. [Figure 8] This is the construction procedure for offshore wind power generation facility 1 (part 1). [Figure 9] This is the construction procedure for offshore wind power generation facility 1 (part 2). [Figure 10] This is the construction procedure for offshore wind power generation facility 1 (part 3). [Figure 11] This is the construction procedure for offshore wind power generation facility 1 (part 4). [Figure 12] This is the construction procedure for offshore wind power generation facility 1 (part 5). [Figure 13] This is the construction procedure for offshore wind power generation facility 1 (part 6). [Figure 14] This is the construction procedure for offshore wind power generation facility 1 (part 7). [Figure 15] This is the construction procedure for offshore wind power generation facility 1 (part 8). [Figure 16] FIG. 4 is a plan view showing a modified example of the construction crane equipment 30. [Figure 17] FIG. 1 is an overall side view of a construction auxiliary crane facility 41 installed side by side. [Figure 18] FIG. 13 is a side view showing a case where floating bodies 4 are connected to each other during construction. [Figure 19] FIG. 11 is a plan view showing the case where mooring lines 43 are attached to each floating body 4 during construction. [Figure 20] 1 shows a construction procedure (part 1) of the offshore wind power generation facility 1 according to the second embodiment. [Figure 21] 11 shows a construction procedure (part 2) of the offshore wind power generation facility 1 according to the second embodiment. [Figure 22] 11 shows a construction procedure (part 3) of the offshore wind power generation facility 1 according to the second embodiment. [Figure 23] 13 shows a construction procedure (part 4) of the offshore wind power generation facility 1 according to the second embodiment. [Figure 24]5 shows a construction procedure (part 5) of the offshore wind power generation facility 1 according to the second embodiment. [Diagram 25] 6 shows a construction procedure (part 6) of the offshore wind power generation facility 1 according to the second embodiment. [Figure 26] FIG. 1 is a flow chart showing a conventional floating body construction method. [Figure 27] FIG. 1 is a cross-sectional view showing a method for reinforcing a concrete ring 60 (Patent Document 3). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0038] [Hybrid spar type floating offshore wind turbine 1] First, a spar-type offshore wind power generation facility 1 to which the present invention is applied will be described in detail with reference to Figs. 1 to 5.

[0039] As shown in detail in Figure 1, the spar-type offshore wind power generation facility 1 is composed of a spar-type cylindrical floating body 4, mooring lines 5, a tower 6, and a wind turbine 7 consisting of a nacelle 8 installed on the top of the tower 6 and a number of blades 9, 9...

[0040] As shown in FIG. 2, the float 4 comprises a concrete floating section 4A in which concrete precast cylindrical bodies 15, 15... are stacked vertically in multiple tiers and each precast cylindrical body 15, 15... is fastened together with PC steel members 19 to form an integrated body, and a steel floating section 4B connected to the upper side of the concrete floating section 4A.

[0041] Ballast materials such as water, gravel, fine aggregate, coarse aggregate, and metal particles can be charged or discharged into or from the hollow portion of the floating body 4, making the buoyancy (draft) adjustable. The charging / discharging of ballast materials is possible by employing the fluid transport method previously proposed by the applicant in JP 2012-201217 A.

[0042] The concrete floating section 4A is composed of concrete precast cylindrical bodies 15, 15.... As shown in Fig. 3, the precast cylindrical bodies 15 are circular cylindrical precast members having the same cross section in the axial direction, and each is manufactured using the same formwork, or a hollow precast member manufactured by centrifugal molding is used.

[0043] In addition to the reinforcing bars 20, sheaths 21, 21... for inserting the PC steel bars 19 are embedded in the wall surface at appropriate intervals in the circumferential direction. The lower ends of these sheaths 21, 21... are formed with sheath enlarged diameter sections 21a so that couplers for connecting the PC steel bars 19 can be inserted, and the upper sections are formed with box-opening sections 22 for fitting in anchor plates for fixing. In addition, a plurality of hanging fittings 23 are provided on the upper surface.

[0044] As shown in Fig. 4(A), the precast cylindrical bodies 15 are fastened together by stacking the precast cylindrical bodies 12, 12 while inserting the PC steel members 19, 19... extending upward from the lower precast cylindrical body 15 into the sheaths 21, 21..., and then fitting the anchor plate 24 into the box-out portion 22 and introducing tension into the PC steel members 19 with the nut member 25 to integrate them. Furthermore, grout material is injected into the sheath 21 from the grout injection hole 27. The hole 24a formed in the anchor plate 24 is a grout injection confirmation hole, and the filling of the grout material is completed when the grout material is discharged from the confirmation hole.

[0045] 4(B), couplers 26 are screwed onto the protruding parts of the prestressing steel 19 to connect the upper prestressing steel members 19, 19..., and then the prestressing steel members 19, 19... are stacked while being inserted into the sheaths 21, 21... of the upper precast tubular body 15, and the procedure of fixing the prestressing steel members 19 in place in the above manner is repeated in order to stack them up in the height direction. At this time, an adhesive 28 such as an epoxy resin-based adhesive or sealant is applied to the joint surfaces between the lower precast tubular body 15 and the upper precast tubular body 15 to ensure watertightness and to bond the mating surfaces.

[0046] The steel floating body section 4B is composed of a steel cylindrical body 17 located relatively on the lower side, and a steel cylindrical body 18 located relatively on the upper side. The lower part of the steel cylindrical body 17 on the lower side has the same outer diameter as the precast cylindrical body 15, and as shown in Figure 5, it is connected to the precast cylindrical body 15 by bolts or welding (bolt fastening is shown in the illustrated example). The upper part of the steel cylindrical body 17 forms a truncated cone shape with a gradually narrowing diameter.

[0047] The upper steel cylindrical body 18 is a cylindrical body with an outer diameter dimension that is continuous with the upper outer diameter of the lower steel cylindrical body 17, and is connected to the lower steel cylindrical body 17 by bolts or welding or the like (bolt fastening is shown in the illustrated example). These steel cylindrical bodies 17, 18 are composed of steel rings 10, 10... that are divided into predetermined weights, and the steel rings 10, 10... are integrated by welding them in the circumferential direction.

[0048] On the other hand, the tower 6 is made of steel, concrete or PRC (prestressed reinforced concrete), but it is preferable to use one made of steel so that the total weight is small. The outer diameter of the tower 6 and the outer diameter of the upper steel cylindrical body 18 are almost the same, and the outer shape is continuous in the vertical direction without any steps. In the illustrated example, a ladder 13 is provided on the top of the upper steel cylindrical body 18, and a walkway scaffolding 14 is provided in the circumferential direction at approximately the boundary between the tower 6 and the upper steel cylindrical body 18.

[0049] As shown in Fig. 1, the mooring point P of the mooring line 5 to the float 4 is set below the sea surface and at a position higher than the center of gravity G of the float 4. This makes it possible to prevent a ship from coming into contact with the mooring line 5. Also, since a resistance moment is generated around the center of gravity G of the float 4 at the mooring point P so as to prevent the float 4 from tipping over too much, the tilting attitude of the tower 6 can be appropriately maintained.

[0050] On the other hand, the nacelle 8 is a device equipped with a generator that converts the rotation of the wind turbine 7 into electricity, a controller that can automatically change the angle of the blades 9, and the like.

[0051] [Construction method for spar-type offshore wind power generation facility 1] Next, a method for constructing the spar-type offshore wind power generation facility 1 will be described in detail with reference to Figs.

[0052] The float 4 of the spar-type offshore wind power generation facility 1 that is the subject of the present invention is a spar-type float consisting of a concrete floating body section 4A in which concrete precast cylindrical bodies 15, 15... (hereinafter referred to as concrete rings) are stacked vertically in multiple layers and each concrete ring 15, 15... is fastened and integrated with PC steel members 19, and a steel floating body section 4B connected to the upper side of this concrete floating body section 4A.

[0053] By making the floating structure consisting of the concrete floating body 4A and the steel floating body 4B, the center of gravity can be lowered, which increases the stability of the floating body and enables the length of the floating body to be reduced. Since the part protruding above the sea is made of steel, it has an advantage against collisions with ships.

[0054] In the conventional method of constructing the float 4, the float was assembled in a horizontal position in a production yard on land. However, in the construction method of the present invention, the concrete rings 15, 15... are first assembled in the minimum number of stages required to float the float, and these are initially floated vertically on the sea. From this state, the remaining concrete rings 15, 15... are assembled in order to complete the concrete floating section 4A, and then the steel floating section 4B is connected on top of it to complete the float 4.

[0055] The construction method will be described in detail below with reference to the drawings.

[0056] <First step> 6 and 7, at an offshore site for constructing the spar-type offshore wind power generation facility 1, which has been selected on the condition that it is a calm area with a water depth sufficient to float the float 4, a construction crane facility 30 having a tower crane 32 mounted on the upper surface of a base float 31 is installed on the sea. On the side of the base float 31, multiple float gripper mechanisms 34, 34 for holding the spar-type float 4 under construction (three in the illustrated example) are provided.

[0057] The base float 31 is a float that serves as a support structure (foundation) for installing the tower crane 32 on the sea, and can be a "barge type" float with a shallow draft that floats on the water surface, or a "semi-submersible type" float with the lower part of the float submerged below the water surface, which have a proven track record as floats for offshore wind power generation facilities. In the illustrated example, a semi-submersible float is used, with three floaters 33 arranged at each corner of a triangle and connected by connecting materials or the like, and mooring ropes 35 attached to each floater 33 for stability on the sea.

[0058] The tower crane 32 is installed on the upper surface of the base float 31 as a base. This tower crane 32 is used for assembling the concrete floating body part 4A and the steel floating body part 4B, as well as for assembling the tower 6, nacelle 8, and wind turbine 7 (blades 9, 9, ...) which are assembled thereafter. Among these, the steel floating body part 4B is a fairly heavy object since it is constructed as a single unit. In addition, the tower 6 and the nacelle 8 which are connected to the upper side of the float 4 are also quite heavy objects. Therefore, as shown in FIG. 17, when the scale of the spar-type offshore wind power generation facility 1 is large, it is preferable to install an auxiliary construction crane facility 41, which has a tower crane 32 installed on the upper surface of the base float 31, in a position adjacent to the construction crane facility 30, in addition to the construction crane facility 30, and to use the two tower cranes 32, 32 cooperatively (co-hoisting work) to assemble these heavy objects.

[0059] The float gripper mechanisms 34 provided on the sides of the base float 31 are provided for each of the three floaters 33. As shown in Fig. 7, the float gripper mechanism 34 is U-shaped in a plan view so that the float 4 can be inserted into the float gripper mechanism 34. The gripper arm portion 32a (hereinafter, the movable arm) on the opening tip side is movable in the opening and closing directions, and the float 4 can be held so as not to move by closing the movable arm 34a with the float 4 inserted. The held float 4 is held so as not to move laterally, but is allowed to move up and down.

[0060] The number of the float gripper mechanisms 34 can be increased or decreased within a certain range. For example, if four float gripper mechanisms 34 are to be provided, the base float 30 is configured to have a rectangular shape in plan view, with floaters 33 arranged at each corner and connected by connecting materials or the like, and a float gripper mechanism 34 is provided at each location of each floater 33, as shown in FIG.

[0061] Since the draft of the base float 31 is shallow, the construction crane equipment 30 (including the construction auxiliary crane equipment 41) can be adapted to load the tower crane 32 onto the base float 31 while it is floating in the quay yard, and then transport it in that state to the construction site by a towing ship.

[0062] <Second step> In the second step, the concrete ring units 11, 11... assembled from multiple tiers of concrete rings 15, 15... starting from the bottom tier are transported by a transport barge 36 to the offshore location where the spar-type offshore wind power generation facility 1 will be constructed, and then this concrete ring unit 11 is floated on the sea and held by the floating body gripper mechanism 34.

[0063] Specifically, as shown in FIG. 8, in a wharf yard, a concrete ring unit 11 is assembled by stacking and connecting multiple layers from the bottom concrete ring 15 upward, and is placed on a transport barge 36 and transported to the offshore construction site by a towing ship 37. The number of assembled layers of the concrete rings 15 is determined by calculation so that the concrete rings 15 have buoyancy to float on the sea. In the illustrated example, a semi-submersible spud barge is used as the transport barge 36. This semi-submersible spud barge 36 is a barge whose draft can be adjusted to a semi-submerged state by adjusting the ballast water, and after the cargo is rolled on (loaded) onto the barge while adjusting the ballast water, the cargo can be floated off (surfaced and launched) by adjusting the ballast water offshore to a semi-submerged state. Therefore, once the concrete ring unit 11 is transported to the construction site, it becomes possible to float and launch the concrete ring unit 11 on the sea in a semi-submerged state without a crane.

[0064] The floated-off concrete ring unit 11 is held by a floating body gripper mechanism 34 provided on the base floating body 31, as shown in Fig. 9. Specifically, for example, a wire 38 connected to the concrete ring unit 11 is pulled by a winch 39, and the concrete ring unit 11 is guided to a position while applying a braking force to the concrete ring unit 11 by a towing vessel 37, and the concrete ring unit 11 is carefully inserted into the floating body gripper mechanism 34, and then the movable arm 32a is closed to hold the concrete ring unit 11. Fig. 10 shows the state in which the concrete ring unit 11 is held by the floating body gripper 32.

[0065] <Third step> Next, in the third step, the tower crane 32 is used to stack concrete rings 15, 15... in sequence on top of the concrete ring unit 11, and the procedure of fastening them with PC steel 19 to integrate them is repeated to complete the concrete floating section 4A.

[0066] Specifically, as shown in Fig. 11, the remaining concrete rings 15, 15... are loaded onto a loading barge 40 and towed to the construction site. Then, using a tower crane 32, the concrete rings 15, 15... are stacked on top of the concrete ring unit 11 and fastened with PC steel 19. This procedure is repeated to complete the concrete floating section 4A.

[0067] Regarding the assembly of the concrete rings 15, 15..., as in the illustrated example, the concrete rings 15 may be assembled one layer at a time, or multiple layers, for example two layers, may be assembled in advance, and the assembled multiple layers of concrete rings 15, 15 may then be stacked together, thereby reducing the labor required for on-site work.

[0068] <Fourth step> In the fourth step, as shown in FIG. 12, the steel floating section 4B is transported to the construction site by a transport barge 40, and then, as shown in FIGS. 13 and 14, the steel floating section 4B is suspended by a tower crane 32 and connected to the upper side of the concrete floating section 4A to complete the float 4.

[0069] <5th step> In the fifth step, as shown in FIG. 15, the tower crane 32 is used to mount the tower 6 on top of the floating body 4, and then the nacelle 8 and blades 9, 9... (wind turbine 7) are attached to complete the spar-type offshore wind power generation facility 1.

[0070] <Other> (1) It is desirable to adjust the draft by adding or removing ballast at any time during the first to fifth steps. By adjusting the draft of the incomplete float 4 at the appropriate time, the float 4 can be stabilized.

[0071] (2) In order to improve the stability of the float 4, as shown in Figure 18, during the construction of the float 4 or after the float is completed, during the construction of the offshore wind power generation facility 1, each float 4, 4 ... may be connected to each other by connecting materials 42.

[0072] (3) In order to improve the stability of the float 4, as shown in Figure 19, during the construction of the float 4 or after the float is completed, during the construction of the offshore wind power generation facility 1, mooring lines 43, 43 may be installed on each float 4 to improve stability.

[0073] [Second embodiment example] Next, as a second embodiment, a construction method for constructing the float 4 all at once will be described. This second embodiment is premised on the use of a semi-submersible spud barge 36, but it is not necessary to reinforce the concrete rings, and since no extra load acts on the concrete rings, it is possible to prevent cracks and damage, and it is possible to float the float in an erected state on the sea by performing only the float-off operation, which makes it possible to improve the efficiency of the assembly work.

[0074] <First step> The first step of installing a construction crane facility 30 on the sea, which includes a tower crane 32 mounted on a base float 31 and a plurality of float gripper mechanisms 34 for holding the spar-type float 4 under construction on the side of the base float 31, is exactly the same as in the first embodiment described above.

[0075] <Second step> In the second step, the entire float is first assembled at the quay, and then the completed float 4 is transported by a semi-submersible spud barge 36 to the construction site of the spar-type offshore wind power generation facility, and once the float 4 is floated offshore, it is held by the float gripper mechanism 34.

[0076] More specifically, the float 4 is first completed in a wharf yard. As a method for constructing the float, the method proposed by the present applicant in JP 2018-173011 A can be suitably adopted.

[0077] The floating structure construction method is as shown in FIG. 20, in which a steel ring connection yard A, a concrete ring fabrication yard B, and a concrete ring connection yard C are defined in a wharf yard.

[0078] In the steel ring connecting yard A, a first bridge crane 50 is installed so that it can travel in a fixed direction, rotating platforms 52, 52... are installed at appropriate intervals in the direction of travel of the first bridge crane, and a mobile tent 56 is also provided that can move in the direction of travel of the first bridge crane. In the concrete ring production yard B, a mobile tent 57 is installed, and a complete set of concrete ring manufacturing equipment is also installed. In the concrete ring connecting yard C, a second bridge crane 55 is installed so that it can travel in a fixed direction, and a mobile tent 58 is also provided that can move in the direction of travel of the second bridge crane.

[0079] The method for constructing a float for a floating offshore wind power facility includes a first step of installing the steel rings 51, 51... on the rotating frames 52, 52... in order using the first bridge crane 50, and covering them with a mobile tent 56 if necessary, and connecting the steel rings 51, 51... by welding them circumferentially while rotating them about their axis, thereby completing the steel floating body section 53B; and a second step of moving the steel floating body section 53B to the concrete ring connecting yard C and installing it in a predetermined position, and then transporting the concrete rings 54 fabricated in the concrete ring fabrication yard B to the concrete ring connecting yard C in order, covering them with a mobile tent 58 if necessary, and connecting the concrete rings 54 to the steel floating body section 53B using the second bridge crane 55, and fastening them together with PC steel to complete the float 53. Once the floating body 4 has been completed in this manner, as shown in FIG. 21, it is moved sideways to a semi-submersible spud barge 36 at the quay and loaded onto it (rolled on).

[0080] Next, the semi-submersible spud barge 36 is towed by a towing vessel 37 and transported to the construction site of the spar-type offshore wind power generation facility (see FIG. 22), and the floater 4 is launched and floated on the sea (rolled off) by putting the semi-submersible spud barge 36 into a semi-submerged state as shown in FIG. 23. Then, the floater is raised upright by injecting ballast water into it, and placed in a vertical position.

[0081] As shown in Figure 24, the float 4 floating on the sea is pulled in by a wire 42 paid out from a winch 41 installed on the construction crane equipment 30, and its position is guided while applying braking force by a towing vessel 37. After that, the float 4 is carefully inserted into the float gripper mechanism 34, and the movable arm 34a is closed to hold the float 4.

[0082] <Third step> In the third step, as shown in Figure 25, the tower crane 32 is used to mount the tower 6 on top of the floating body 4, and then the nacelle 8 and blades 9, 9... (wind turbine 7) are attached to complete the spar-type offshore wind power generation facility 1.

[0083] [Other examples] (1)) The above embodiment is directed to a spar-type float in which the float 4 is made up of a concrete floating body section 4A and a steel floating body section 4B connected to the upper side of the concrete floating body section 4A, but it is also possible to construct a spar-type float in which the float 4 is made up of only the concrete floating body section 4A in which the concrete rings 15, 15... are stacked in a plurality of stages and each concrete ring 15, 15... is fastened and integrated with PC steel members 19. Specifically, the concrete float 4 is completed according to steps 1 to 3 of the spar-type float described above, and then in step 4, the tower 6 is mounted on the top of the concrete float 4B using the tower crane 32, and the nacelle 8 and the blades 9, 9... are attached to complete the spar-type offshore wind power generation facility 1.

[0084] Furthermore, when constructing the concrete float 4 all at once as in the second embodiment, once the concrete float 4 has been completed at the quay yard, the spar-type offshore wind power generation facility 1 is completed using the same procedure as in the second embodiment described above. [Explanation of symbols]

[0085] 1...Spar-type offshore wind power generation equipment, 4...Floating body, 4A...Concrete floating body section, 4B...Steel floating body section, 5...Mooring line, 6...Tower, 7...Wind turbine, 8...Nacelle, 9...Blade, 11...Concrete ring unit, 15-16...Precast cylindrical body (concrete ring), 19...PC steel, 30...Construction crane equipment, 31...Base floating body, 32...Tower crane, 33...Floater, 34...Floating body gripper mechanism, 35-43...Mooring line, 36...Transport barge (semi-submersible spud barge), 40...Loading barge, 37...Tow boat, 41...Construction auxiliary crane equipment, 42...Connecting material

Claims

1. A method for constructing a spar-type offshore wind power generation facility includes a spar-type floater including a concrete floating body section in which concrete rings are stacked in a plurality of tiers and each concrete ring is fastened and integrated with PC steel, and a steel floating body section connected to the upper side of the concrete floating body section, A first step of mounting a tower crane on a base float and installing a construction crane facility on the sea, the construction crane facility having a plurality of float gripper mechanisms for holding a spar-type float under construction on a side of the base float; A second step of floating a concrete ring unit formed by assembling multiple concrete rings from the bottom side on the sea and holding the concrete ring unit by the floating gripper mechanism; a third step of stacking concrete rings in sequence on the upper side of the concrete ring unit using the tower crane and fastening them with PC steel members to complete a concrete floating body portion; a fourth step of connecting the steel floating body section to an upper side of the concrete floating body section using the tower crane to complete the floating body; and a fifth step of using the tower crane to mount a tower on top of the float, and further attaching a nacelle and blades to complete the spar-type offshore wind power generation facility.

2. A method for constructing a spar-type offshore wind power generation facility includes a spar-type floater including a concrete floating body section in which concrete rings are stacked in a plurality of tiers and each concrete ring is fastened and integrated with PC steel, and a steel floating body section connected to the upper side of the concrete floating body section, A first step of mounting a tower crane on a base float and installing a construction crane facility on the sea, the construction crane facility having a plurality of float gripper mechanisms for holding a spar-type float under construction on a side of the base float; a second step of assembling the entire float on the quay, transporting the completed float to a construction site of the spar-type offshore wind power generation facility by a semi-submersible spud barge, and holding the float by the float gripper mechanism once the float has been floated offshore; a third step of using the tower crane to mount a tower on top of the float, and then attaching a nacelle and blades to complete the spar-type offshore wind power generation facility.

3. A method for constructing a spar-type offshore wind power generation facility having a spar-type float made of concrete, the spar-type float being made of concrete floats stacked in a plurality of tiers and each concrete ring being fastened and integrated with PC steel members, comprising: A first step of mounting a tower crane on a base float and installing a construction crane facility on the sea, the construction crane facility having a plurality of float gripper mechanisms for holding a spar-type float under construction on a side of the base float; A second step of floating a concrete ring unit formed by assembling multiple concrete rings from the bottom side on the sea and holding the concrete ring unit by the floating gripper mechanism; a third step of stacking concrete rings in sequence on the upper side of the concrete ring unit using the tower crane and fastening them with PC steel members to complete a concrete floating body; and a fourth step of using the tower crane to mount a tower on top of the concrete float, and further attaching a nacelle and blades to complete the spar-type offshore wind power generation facility.

4. A method for constructing a spar-type offshore wind power generation facility having a spar-type float made of concrete, the spar-type float being made of concrete floats stacked in a plurality of tiers and each concrete ring being fastened and integrated with PC steel members, comprising: A first step of mounting a tower crane on a base float and installing a construction crane facility on the sea, the construction crane facility having a plurality of float gripper mechanisms for holding a spar-type float under construction on a side of the base float; a second step of assembling the entire float on the quay, transporting the completed float to a construction site of the spar-type offshore wind power generation facility by a semi-submersible spud barge, and holding the float by the float gripper mechanism once the float has been floated offshore; a third step of using the tower crane to mount a tower on top of the float, and then attaching a nacelle and blades to complete the spar-type offshore wind power generation facility.

5. A method for constructing a spar-type offshore wind power generation facility according to any one of claims 1 to 4, wherein ballast is injected into or discharged from the float at any time during each step to adjust the draft.

6. A method for constructing a spar-type offshore wind power generation facility according to any one of claims 1 to 4, wherein the floats are interconnected during construction or after completion of the floats to improve stability.

7. A method for constructing a spar-type offshore wind power generation facility according to any one of claims 1 to 4, wherein stability is improved by installing mooring ropes to each float during construction of the float or after completion of the float.

8. A construction method for a spar-type offshore wind power generating facility according to any one of claims 1 to 4, further comprising the step of: providing an auxiliary construction crane facility having a tower crane installed on the upper surface of the base floating body in an adjacent position in addition to the construction crane facility.

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