Construction method for spar-type offshore wind power generation facility

Abstract

To be capable of stably constructing a spar-type offshore wind power generation facility.SOLUTION: A construction method for constructing a spar-type offshore wind power generation facility includes: first and second steps for installing a crane facility for construction 40 composed of a jacket foundation 30, a tower crane 35, and a floating body gripper mechanism 36 offshore; a third step for floating on the sea a concrete ring unit 11 assembled from a plurality of tiers of concrete rings 15 from a bottom most tier side and retaining by the gripper mechanism 36; a fourth step for completing a concrete floating body unit 4A by a procedure of stacking up the concrete rings 15 in order on top side of the concrete ring unit 11 as well as obtaining integration by binding with PC steel 19; a fifth step for completing the a floating body 4 by coupling a steel floating unit 4B to top unit side of the concrete floating body unit 4A; and a sixth step for loading a tower 6 on a top unit of the floating body 4, and furthermore carrying out attachment of a nacelle 8 and a blade 9 and completing the spar type offshore wind power generation facility 1.SELECTED DRAWING: Figure 15

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 a barge type float, which floats on the water surface, a semi-submersible type, in which the lower part of the float is submerged below the water surface to float in a semi-submerged state, and a spar type, which 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 in a bay with calm waves; however, the draft (part below the water surface) of the spar-type float is deep, at approximately 70 m or more, while the water in a bay is generally shallower than this, making construction in the bay difficult. As such, the installation of the wind turbine equipment has traditionally been carried out outside the bay where the water is deep, using a large crane ship 70, as shown in Figure 28 (see Patent Document 4).

[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 on the ocean outside a bay, 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, Once the jacket foundation is transported to the construction site of the spar-type offshore wind power generation facility, the first step is to erect the jacket foundation using a crane ship and secure the jacket foundation to the seabed by driving pin piles; A second step of mounting a tower crane on the top of the jacket foundation using a crane ship and providing one or more float gripper mechanisms for holding the spar-type float under construction on the top of the jacket foundation, thereby completing the construction crane equipment for the spar-type offshore wind power generation facility offshore; A third 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 fourth 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 fifth 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 sixth 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, the jacket foundation is transported or towed to the construction site of the spar-type offshore wind power generation facility, the jacket foundation is erected using a crane ship, and the jacket foundation is fixed to the seabed by driving pin piles. Next, a tower crane is mounted on the top of the jacket foundation using a crane ship, and one or more floater gripper mechanisms for holding the spar-type float under construction are installed on the top of the jacket foundation, completing the construction crane equipment for the spar-type offshore wind power generation facility offshore (first and second steps).

[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 (third 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 (fourth 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 (step 5). 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 (sixth step).

[0020] The crane used in the present invention is a construction crane equipment mounted on the top of the jacket foundation, and is highly stable, making it easy to align with the installation target during erection. In addition, the stability of the float being held by the float gripper mechanism during construction is increased, making it possible to safely and stably construct a spar-type offshore wind power generation facility 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: Once the jacket foundation is transported to the construction site of the spar-type offshore wind power generation facility, the first step is to erect the jacket foundation using a crane ship and secure the jacket foundation to the seabed by driving pin piles; A second step of mounting a tower crane on the top of the jacket foundation using a crane ship and providing one or more float gripper mechanisms for holding the spar-type float under construction on the top of the jacket foundation, thereby completing the construction crane equipment for the spar-type offshore wind power generation facility offshore; A third step of assembling the entire float on the wharf, transporting the completed float to the 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 after the float is floated off the ocean; There is provided a method for constructing a spar-type offshore wind power generation facility, characterized by comprising a fourth 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 (third 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 (fourth 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: Once the jacket foundation is transported to the construction site of the spar-type offshore wind power generation facility, the first step is to erect the jacket foundation using a crane ship and secure the jacket foundation to the seabed by driving pin piles; A second step of mounting a tower crane on the top of the jacket foundation using a crane ship and providing one or more float gripper mechanisms for holding the spar-type float under construction on the top of the jacket foundation, thereby completing the construction crane equipment for the spar-type offshore wind power generation facility offshore; A third 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 fourth 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; 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 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 method of construction for a concrete float in which the entire float is made of concrete. Basically, after completing the float in the procedure from step 1 to step 4 of the invention described in claim 1, the tower, nacelle, and blades are attached in step 5 to complete the offshore wind power generation facility. As with the invention described in claim 1 above, the float is assembled while floating on the sea, so 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, since the float is floating vertically when all the floating body components have been assembled, there is no need to perform a process of erecting the float, which makes it possible to improve the efficiency of the assembly work.

[0025] The invention according to claim 4 is a method for constructing a spar-type offshore wind power generation facility equipped with a spar-type float made of concrete, which is formed by stacking concrete rings in a plurality of stages and fastening and integrating each concrete ring with PC steel, comprising: Once the jacket foundation is transported to the construction site of the spar-type offshore wind power generation facility, the first step is to erect the jacket foundation using a crane ship and secure the jacket foundation to the seabed by driving pin piles; A second step of mounting a tower crane on the top of the jacket foundation using a crane ship and providing one or more float gripper mechanisms for holding the spar-type float under construction on the top of the jacket foundation, thereby completing the construction crane equipment for the spar-type offshore wind power generation facility offshore; A third step of assembling the entire float on the wharf, transporting the completed float to the 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 after the float is floated off the ocean; There is provided a method for constructing a spar-type offshore wind power generation facility, characterized by comprising a fourth 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 stabilize the incomplete floating body by adjusting the draft by injecting or discharging ballast into or from the floating body at any time during each step. Effect of the Invention

[0029] 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 on the ocean outside a bay, without using a large crane ship. [Brief description of the drawings]

[0030] [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] This is a diagram of the transportation. [Figure 8] 1 shows a construction procedure (part 1) of the offshore wind power generation facility 1 according to the first embodiment. [Figure 9] 1 shows a construction procedure (part 2) of the offshore wind power generation facility 1 according to the first embodiment. [Figure 10] 13 shows a construction procedure (part 3) of the offshore wind power generation facility 1 according to the first embodiment. [Figure 11] 11 shows a construction procedure (part 4) of the offshore wind power generation facility 1 according to the first embodiment. [Figure 12] 5 is a construction procedure (part 5) of the offshore wind power generation facility 1 according to the first embodiment. [Figure 13] 6 shows a construction procedure (part 6) of the offshore wind power generation facility 1 according to the first embodiment. [Figure 14] 7 shows a construction procedure (part 7) of the offshore wind power generation facility 1 according to the first embodiment. [Figure 15] 8 shows the construction procedure (part 8) of the offshore wind power generation facility 1 according to the first embodiment. [Figure 16] 9 is a construction procedure (part 9) of the offshore wind power generation facility 1 according to the first embodiment. [Figure 17] 10 shows a construction procedure (part 10) of the offshore wind power generation facility 1 according to the first embodiment. [Figure 18] 11 is a construction procedure (part 11) of the offshore wind power generation facility 1 according to the first embodiment. [Figure 19] 12 is a construction procedure (part 12) of the offshore wind power generation facility 1 according to the first embodiment. [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. [Diagram 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). [Figure 28] FIG. 1 is a diagram showing a procedure for integrated construction using a large crane ship 70 in Patent Document 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0032] [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.

[0033] 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...

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] [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.

[0046] 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.

[0047] 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.

[0048] In the conventional method of constructing the float 4, the float is assembled in a horizontal position in a production yard on land. However, in the construction method according to the first embodiment 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.

[0049] The construction method will be described in detail below with reference to the drawings.

[0050] [First embodiment] <First step> First, as shown in Fig. 6, the jacket foundation 30 is loaded onto a loading barge 31 at a quay yard, and then, as shown in Fig. 7, it is transported to an offshore location with a certain degree of water depth by a towing ship 32. Next, as shown in Fig. 8, the jacket foundation 30 is floated on the sea by launching (a construction method in which a barge is tilted to slide down into the sea).

[0051] The floating jacket foundation 30 is towed (transported) by a towing ship 32 to the construction site of the spar-type offshore wind power generation facility, as shown in Fig. 9. A ballast tank (not shown) is attached to the jacket foundation 30, allowing for draft adjustment. If the water in the wharf yard is deep, the jacket foundation 30 may be floated on the sea directly at the wharf and towed (transported) by the towing ship 32.

[0052] Once the construction site is reached, the jacket foundation 30 is erected and temporarily placed on the seabed using a crane barge 33, as shown in Fig. 10. The jacket foundation is sunk by injecting seawater into the ballast tanks while the top of the jacket foundation is supported by the crane barge 33.

[0053] Next, as shown in FIG. 11, pin piles 34 are driven through the legs 30a of the jacket foundation 30 using a hydraulic hammer 37 suspended by a crane ship 33, and then grout is injected to fix the jacket foundation 30 to the seabed.

[0054] <Second step> Next, as shown in Figure 12, a tower crane 35 is mounted on the top (deck) of the jacket foundation 30 using a crane ship 33, and one or more floater gripper mechanisms 36 (one in the illustrated example) for holding the spar-type float under construction are provided on the top of the jacket foundation 30, and a crane facility 40 for constructing the spar-type offshore wind power generation facility is completed offshore.

[0055] The tower crane 35 is used for assembling the concrete floating body section 4A and the steel floating body section 4B, as well as for assembling the tower 6, nacelle 8, and wind turbine 7 (blades 9, 9...), which are to be assembled subsequently. This tower crane 36 is a mast climbing type crane, in which the base of the crane does not move from the position where it was originally installed, and the mast (support) that supports the crane is added to the upper part by itself, and the crane part climbs up the extended part.

[0056] As shown in FIG. 13(B), the float gripper mechanism 36 is U-shaped in a plan view so that the float 4 can be inserted into the float gripper mechanism 36. The gripper arm portion 36a (hereinafter, the movable arm) at the opening end side can move in the opening and closing directions, and the float 4 can be held so as not to move by closing the movable arm 36a 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. Regarding the number of float gripper mechanisms 36 to be installed, one is shown in the illustrated example, but up to four can be installed, one on each side of the top (deck) of the jacket foundation 30.

[0057] <Third step> In the third 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 38 to the offshore location where the spar-type offshore wind power generation facility 1 will be constructed, and then the concrete ring unit 11 is floated on the sea and held by the floating body gripper mechanism 36.

[0058] Specifically, as shown in FIG. 14, in a wharf yard, a concrete ring unit 11 is assembled by stacking and connecting several tiers of concrete rings 15 upward from the lowest tier, and then loaded onto a transport barge 38 and transported to the offshore construction site by a towing ship 32. The number of tiers of the concrete rings 15 to be assembled 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 38. This semi-submersible spud barge 38 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.

[0059] The floated-off concrete ring unit 11 is held by a floating body gripper mechanism 36 provided on the jacket foundation 30, as shown in Fig. 15. For example, the wire connected to the concrete ring unit 11 is pulled by a winch, and the concrete ring unit 11 is guided into position by a towing vessel 32 while applying a braking force to the concrete ring unit 11, and the concrete ring unit 11 is carefully inserted into the floating body gripper mechanism 36, and then the movable arm 36a is closed to hold the concrete ring unit 11. Fig. 15 shows the state in which the concrete ring unit 11 is held by the floating body gripper mechanism 36.

[0060] <Fourth step> Next, in the fourth step, the tower crane 35 is used to stack the 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.

[0061] Specifically, as shown in Fig. 15, the remaining concrete rings 15, 15... are loaded onto a loading barge 39 and towed to the construction site. Then, as shown in Fig. 16, a tower crane 35 is used to stack the concrete rings 15, 15... on top of the concrete ring unit 11 and fasten them with PC steel 19. This procedure is repeated to complete the concrete floating section 4A.

[0062] 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.

[0063] <5th step> In the fourth step, as shown in FIG. 17, the steel floating section 4B is transported to the construction site by a loading barge 39, and then, as shown in FIG. 18, the steel floating section 4B is suspended by a tower crane 35 and connected to the upper side of the concrete floating section 4A to complete the float 4.

[0064] <Sixth step> In the sixth step, as shown in FIG. 19, the tower crane 35 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.

[0065] <Other> (1) At any time during the first to sixth steps, it is desirable to adjust the draft by adding or removing ballast to the float 4. By adjusting the draft of the float 4 in an incomplete or completed state at the appropriate time, the float 4 can be stabilized.

[0066] [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 38, 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. <First and second steps> The first step of fixing the jacket foundation 30 to the seabed and the second step of mounting the tower crane 35 on the jacket foundation 30 and providing the floating body gripper mechanism 36 are entirely the same as in the first embodiment described above.

[0067] <Third step> In the third step, the entire float is first assembled at the quay, and then the completed float 4 is transported by a semi-submersible spud barge 38 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 36.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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 38 at the quay and loaded onto it (rolled on).

[0072] Next, the semi-submersible spud barge 38 is towed by the towing vessel 32 and transported to the construction site of the spar-type offshore wind power generation facility (see FIG. 22), and the floating body 4 is launched and floated on the sea surface (rolled off) by putting the semi-submersible spud barge 38 into a semi-submerged state as shown in FIG. 23. Then, the floating body 4 is raised upright by injecting ballast water into it, and placed in a vertical position.

[0073] 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 jacket foundation 30, and its position is guided while applying braking force by the towing vessel 32. After that, the float 4 is carefully inserted into the float gripper mechanism 36, and the movable arm 36a is closed to hold the float 4.

[0074] <Fourth step> In the fourth step, as shown in Figure 25, the tower crane 35 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.

[0075] [Other examples] (1)) The above first and second embodiments are directed to a spar-type float in which the float 4 is composed of a concrete floating section 4A and a steel floating section 4B connected to the upper side of this concrete floating section 4A. However, it is also possible to construct a spar-type float in which the float 4 is composed only of a concrete floating section 4A in which concrete rings 15, 15... are stacked in multiple tiers and each concrete ring 15, 15... is fastened and integrated with PC steel 19, using a similar procedure.

[0076] Specifically, when assembling a concrete float 4 offshore by stacking construction as in the first embodiment, the concrete float 4 is completed following steps 1 to 4 of the spar-type float of the first embodiment described above, and then in the fifth step, the tower 6 is mounted on top of the concrete float 4B using the tower crane 35, and the nacelle 8 and blades 9, 9... are attached to complete the spar-type offshore wind power generation facility 1.

[0077] 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]

[0078] 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...Jacket foundation, 31...Loading barge, 32...Tow barge, 33...Crane barge, 34...Pin pile, 35...Hydraulic hammer, 36...Floating body gripper mechanism, 37...Hydraulic hammer, 38...Semi-submersible spud barge, 39...Loading barge, 40...Construction crane equipment

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, The first step is to transport the jacket foundation to the construction site of the spar-type offshore wind power generation facility, erect the jacket foundation using a crane ship, and fix the jacket foundation to the seabed by driving pin piles; a second step of mounting a tower crane on the top of the jacket foundation using a crane ship and providing one or more float gripper mechanisms for holding the spar-type float under construction on the top of the jacket foundation, thereby completing a crane facility for constructing the spar-type offshore wind power generation facility offshore; A third 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 fourth 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 fifth 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; and a sixth 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, The first step is to transport the jacket foundation to the construction site of the spar-type offshore wind power generation facility, erect the jacket foundation using a crane ship, and fix the jacket foundation to the seabed by driving pin piles; a second step of mounting a tower crane on the top of the jacket foundation using a crane ship and providing one or more float gripper mechanisms for holding the spar-type float under construction on the top of the jacket foundation, thereby completing a crane facility for constructing the spar-type offshore wind power generation facility offshore; a third 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 after the float is floated off into the ocean; and a fourth 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.

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: The first step is to transport the jacket foundation to the construction site of the spar-type offshore wind power generation facility, erect the jacket foundation using a crane ship, and fix the jacket foundation to the seabed by driving pin piles; a second step of mounting a tower crane on the top of the jacket foundation using a crane ship and providing one or more float gripper mechanisms for holding the spar-type float under construction on the top of the jacket foundation, thereby completing a crane facility for constructing the spar-type offshore wind power generation facility offshore; A third 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 fourth step of stacking concrete rings in order 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 fifth 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: The first step is to transport the jacket foundation to the construction site of the spar-type offshore wind power generation facility, erect the jacket foundation using a crane ship, and fix the jacket foundation to the seabed by driving pin piles; a second step of mounting a tower crane on the top of the jacket foundation using a crane ship and providing one or more float gripper mechanisms for holding the spar-type float under construction on the top of the jacket foundation, thereby completing a crane facility for constructing the spar-type offshore wind power generation facility offshore; a third 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 after the float is floated off into the ocean; and a fourth 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.

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.

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