Substructure for floating offshore wind power generation, and construction method for the substructure for floating offshore wind power generation
The floating offshore wind power generation substructure addresses the challenges of increased moments and horizontal forces by using prestressed concrete cylindrical structures with reinforced joints and central reinforcement, enhancing structural integrity and manufacturing efficiency.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- KAJIMA CORP
- Filing Date
- 2022-10-12
- Publication Date
- 2026-06-15
Smart Images
Figure 0007874025000001 
Figure 0007874025000002 
Figure 0007874025000003
Abstract
Description
【Technical Field】 【0001】 The present invention relates to a floating-type offshore wind power generation substructure that supports an offshore wind power generation device, etc. 【Background Art】 【0002】 As an offshore structure such as an offshore wind power generation windmill, a method of supporting a tower, etc. in a floating type has been proposed. Generally, such a floating type substructure is applied at a water depth of, for example, 50 m or more in consideration of costs, etc., as compared with a fixed-type substructure. Further, as the floating type substructure, so-called barge type, semi-sub type, spar type, etc. have been proposed according to the water depth, etc. 【0003】 Here, in the case of a so-called semi-sub type floating body where the overall width is wider than the overall height, a plurality of circular or polygonal cylindrical floating bodies are used, and a cylindrical body (hereinafter simply referred to as "tower, etc.") directly joined below or directly under the tower for wind power generation is generally structured to be connected to other cylindrical floating bodies by connecting members such as horizontal beams in the downward or vertical and horizontal directions (for example, Patent Documents 1 to 3). 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Unexamined Patent Application Publication No. 2018 - 53899 【Patent Document 2】 Japanese Translation of PCT International Publication No. 2017 - 506184 【Patent Document 3】 Japanese Translation of PCT International Publication No. 2018 - 513808 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 In recent years, there has been consideration of increasing the size of wind turbines to achieve cost advantages in terms of wind-receiving efficiency, power generation efficiency, and maintenance efficiency. This means that taller towers are used in conjunction with longer wind-receiving blades. Consequently, the floating substructure itself also needs to be enlarged. 【0006】 As mentioned above, in a typical semi-submersible floating substructure, the tower is connected to other surrounding cylindrical floating bodies by a beam structure. In this case, due to the strength of the wind force on the wings and the oscillation of the floating bodies caused by waves, the tower sways, and so on, the joint with the beam (a connecting member perpendicular to the tower) is subjected to a moment and horizontal force (shear force) associated with the tower's tipping behavior. 【0007】 In a floating substructure with beams only at the lower end, the moment from the tower increases as the distance from the top of the tower to the bottom of the structure increases. Therefore, as the scale of the wind turbine increases, a larger moment is applied to the beam structure at the lower end. For this reason, measures to reduce the moment are required. Furthermore, even if a floating substructure has beams at the top as well to compensate for the lower end, although this increases costs due to the complex shape, since moments and horizontal forces act in all directions depending on the wind direction and wave direction, robust beams are required at both the top and bottom ends. In addition, there is the issue of stress concentration at the beam connection points. 【0008】 On the other hand, conventional floating substructures generally use cylindrical steel floats and beams. However, there are challenges in processing thick steel plates as floating substructures become larger. This is because, compared to Europe, which has been manufacturing thick, large-diameter piles for large wind turbines, Japanese factories lack the processing equipment and manufacturing management know-how to handle the bending of thick steel plates. 【0009】 In response to this, a method using a floating substructure made of concrete has also been proposed. However, even with a concrete substructure, countermeasures are necessary against the moments and horizontal forces that occur at the lower end of towers and the like, as mentioned above. 【0010】 This invention has been made in view of the aforementioned problems, and aims to provide a substructure for floating offshore wind power generation that can be applied to larger scales and can reduce the moment and horizontal force generated at the lower end of the tower, etc. [Means for solving the problem] 【0011】 To achieve the aforementioned objective, the first invention provides a floating offshore wind power generation substructure having a width greater than its height, comprising: an upper deck to which a tower for a wind power generation device is attached; a plurality of hollow cylindrical structures joined to the lower part of the upper deck; and a lower deck joined to the lower ends of the plurality of cylindrical structures. Furthermore, in a plan view, the lower floor slab extends outward beyond the outermost periphery of the cylindrical structure, and the protruding portion is larger than the portion of the upper floor slab that extends outward beyond the outermost periphery of the cylindrical structure. This is a floating offshore wind turbine substructure characterized by the following: The cylindrical structure is preferably circular in shape, which is advantageous for water pressure, and this leads to a reduction in the wall thickness of the cylindrical structure and a corresponding reduction in weight. 【0012】 The second invention is a floating offshore wind power generation substructure having a width greater than its height, comprising: an upper deck to which a tower for a wind power generation device is attached; a plurality of hollow cylindrical structures joined to the lower part of the upper deck; and a lower deck joined to the lower ends of the plurality of cylindrical structures, wherein the cylindrical structures are made of prestressed concrete, and a thickened portion is provided at the joint between the cylindrical structures and the upper deck or the lower deck, the thickened portion is thicker in that its inner diameter is approximately the same as the other parts but its outer diameter is larger, and tensioning members are arranged in the thickened portion, spanning the thickened portion and the upper deck or the lower deck. 【0013】 The third invention is a floating offshore wind power generation substructure having a width greater than its height, comprising: an upper deck to which a tower for a wind power generation device is attached; a plurality of hollow cylindrical structures joined to the lower part of the upper deck; and a lower deck joined to the lower ends of the plurality of cylindrical structures, wherein the cylindrical structures are made of prestressed concrete, and a thickened portion is provided at the joint between the cylindrical structures and the upper deck or the lower deck, the thickened portion is thicker than the other parts by having an outer diameter approximately equal to the outer diameter and a smaller inner diameter, and tensioning members are arranged in the thickened portion, spanning the thickened portion and the upper deck or the lower deck. 【0014】 The fourth invention is a floating offshore wind power generation substructure having a width greater than its height, comprising: an upper deck to which a tower for a wind power generation device is attached; a plurality of hollow cylindrical structures joined to the lower part of the upper deck; and a lower deck joined to the lower ends of the plurality of cylindrical structures, wherein gaps are formed between the plurality of cylindrical structures through which waves can pass; the tower for the wind power generation device is positioned approximately in the center of the upper deck; a central reinforcing structure is provided below the tower for the wind power generation device and below the upper deck; the central reinforcing structure is a cylindrical structure positioned between the upper deck and the lower deck; and the central reinforcing structure has increased strength compared to the other cylindrical structures due to an enlarged diameter or increased thickness. 【0015】 The fifth invention is a floating offshore wind power generation substructure having a width greater than its height, comprising: an upper deck to which a tower for a wind power generation device is attached; a plurality of hollow cylindrical structures joined to the lower part of the upper deck; and a lower deck joined to the lower ends of the plurality of cylindrical structures, wherein reinforcing structures are continuously provided between the cylindrical structures, at least near the joints between the lower surface of the upper deck and the cylindrical structures, so as to connect the cylindrical structures. 【0016】 The reinforcing structure is a reinforcing wall that extends from the upper floor slab to the lower floor slab, and the space enclosed by the reinforcing wall may function as a floating structure. Alternatively, the reinforcing structure may be a reinforcing wall that extends from the upper floor slab to the lower floor slab and has a portion of it that is provided with a penetration for wave passage. 【0017】 The lower and upper floor plates have a shape that can accommodate a plurality of the cylindrical structures, and a constricted shape may be formed between the cylindrical structures with respect to a straight line connecting the outer edges near the joint with the cylindrical structures. 【0018】 The cylindrical structure may be constructed by connecting a plurality of ring members in the longitudinal direction. 【0020】 1 From the 5th invention eitherAccording to the present invention, instead of the conventional beam structure, a cylindrical structure is configured to be sandwiched between a lower floor slab and an upper floor slab, and a tower for a wind power generation device is attached to the upper floor slab, so that the moment generated by the tower can be received by the upper floor slab. Therefore, compared with the case where the moment is received at the lower part (lower floor slab), the distance from the tip of the tower can be shortened, and the moment can be reduced. In addition, the moment and the horizontal force generated by the tower can be received in all horizontal directions of the upper floor slab, rather than in a plurality of limited horizontal directions such as those of a beam. Therefore, even when compared with the case where the moment and the horizontal force are received by the beam at the upper end, the moment and the horizontal force in all directions can be efficiently supported. 【0021】 In the present invention, the tower for the wind power generation device shall include a transition piece or the like directly joined to the tower on which the wind power generation device is mounted. That is, it shall include a joining structure such as a transition piece provided between the upper floor slab and the tower. 【0022】 In addition, by forming a gap between the plurality of cylindrical structures, the wave can pass through the gap. Therefore, the influence of wave force can be suppressed. 【0023】 In addition, by providing a reinforcing structure on the upper floor slab and the lower floor slab between the cylindrical structures, the joining strength at the joint between the upper floor slab and the lower floor slab and the cylindrical structures can be increased. 【0024】 In addition, by arranging the tower for the wind power generation device substantially at the center of the upper floor slab, even if the lower structure becomes larger, it is easier to achieve balance, and it is easier to adjust the attitude, draft, etc. by ballast. At this time, by providing a central reinforcing structure below the tower and at the lower part of the upper floor slab, higher strength can be ensured against the force received from the tower. 【0025】 In this case, a cylindrical structure can be applied as the central reinforcing structure, positioned between the upper and lower floor slabs. This allows for the use of the same cylindrical structure, improving manufacturability and ensuring greater buoyancy. Even in this case, the moment received from the tower, etc., is received by the upper floor slab, thus reducing the moment and horizontal force directly applied to the lower floor slab via the central reinforcing structure. 【0026】 Furthermore, when the cylindrical structure is made of prestressed concrete, a thicker section is provided at the joint between the central reinforcing structure and the upper slab. By placing tensioning members across the thicker section and the upper slab, the joint strength between the central reinforcing structure and the upper slab can be further increased. 【0027】 Furthermore, by making the size of the lower deck larger than the size of the upper deck, and increasing the overhang of the lower deck, vertical movement (heave) of the substructure can be suppressed, and a portion of the lower deck can function as a vibration suppression mechanism. 【0028】 Furthermore, by shaping the lower and upper deck slabs so that the straight lines connecting the outer edges near the joints with multiple cylindrical structures create constricted shapes between the cylindrical structures, it is possible to reduce the weight of the floating substructure and the size of the crane used for assembling the floating structure, especially when a tower or the like is placed on the upper deck slab, and to avoid interference between the crane and the upper deck slab. 【0029】 Furthermore, since the cylindrical structure is constructed by connecting multiple ring members in the longitudinal direction, it can be constructed to the desired length simply by changing the number of connections. In particular, when using concrete, not only are the formwork pieces for each ring the same size (diameter, height, and thickness), but in some cases, the number of cylinders of the same size can be adjusted according to design conditions such as the size of the wind turbine. This results in formwork of the same dimensions, which can be reused and leads to cost reduction. 【0030】 Furthermore, when the cylindrical structure is made of prestressed concrete, a thicker section may be provided at the joint between each cylindrical structure and the upper or lower floor slab, and tensioning members may be placed across the thicker section and the upper or lower floor slab. In this case, the joint strength between the cylindrical structure and the upper or lower floor slab can be further increased. Also, if the direction of the thickening of the cylindrical structure is either outward or inward relative to the general section, the formwork for the inside or outside can be reused. 【0031】 The 6 The invention is It comprises an upper deck slab that is wider than its overall height and to which a tower for a wind turbine is attached, a plurality of hollow cylindrical structures joined to the lower part of the upper deck slab, and a lower deck slab joined to the lower ends of the plurality of cylindrical structures. A method for constructing a substructure for a floating offshore wind power generation system, comprising: step a of constructing the lower deck on top of a movable mechanism near a quay; step b of installing the cylindrical structure on the lower deck; step c of installing the upper deck on the cylindrical structure; and step d of applying prestress to the cylindrical structure between the lower deck and the upper deck, wherein the movable mechanism is moved during at least a portion of the above steps to carry out multiple steps in parallel. 【0032】 In step c, the upper floor plate on the platform may be moved horizontally above the cylindrical structure by another moving mechanism. 【0033】 In step c, the embedded formwork for the upper slab may be moved and positioned above the cylindrical structure by another moving mechanism, and the upper slab may be constructed by pouring concrete into the embedded formwork. 【0034】 The 6 According to this invention, by assembling and moving individual parts of the floating structure near the quay where it will be launched from the shore, the process of transporting the large floating structure can be reduced. Furthermore, by performing each step while moving the structure, multiple steps can be carried out simultaneously. 【0035】 For example, after constructing a cylindrical structure on a lower deck, the upper deck, which was constructed on an adjacent platform or similar structure, can be moved horizontally to efficiently position the large upper deck above the cylindrical structure. 【0036】 Furthermore, by constructing the cylindrical structure on the lower deck slab, then placing the embedded formwork for the upper deck slab above the cylindrical structure, and pouring concrete into the embedded formwork to construct the upper deck slab, a large upper deck slab can be constructed efficiently. [Effects of the Invention] 【0037】 According to the present invention, it is possible to provide a substructure for floating offshore wind power generation that can be applied to larger structures and can reduce the moment and horizontal force generated at the lower end of the tower, etc. [Brief explanation of the drawing] 【0038】 [Figure 1] A diagram showing the usage status of the substructure 1 for a floating offshore wind power generation system. [Figure 2] (a) is a front view showing the substructure 1 for a floating offshore wind power generation system, and (b) is a cross-sectional view of (a) along line AA. [Figure 3] (a) is a front view showing another floating offshore wind turbine substructure 1, and (b) is a cross-sectional view of (a) along line BB. [Figure 4] (a) is a front view showing another floating offshore wind turbine substructure 1, and (b) is a cross-sectional view of (a) along line CC. [Figure 5] (a) to (c) are front views showing other floating offshore wind turbine substructures 1. [Figure 6] (a) is a front view showing another floating offshore wind turbine substructure 1, and (b) is a cross-sectional view of (a) along line DD. [Figure 7] (a) is a front view showing another floating offshore wind turbine substructure 1, and (b) is a cross-sectional view of (a) along line EE. [Figure 8] (a) is a front view showing another floating offshore wind turbine substructure 1, (b) is a line II cross-sectional view of (a), and (c) is a diagram showing another embodiment of (b). [Figure 9] (a) and (b) are diagrams showing other forms of the lower floor slab 9. [Figure 10] A diagram showing the construction process for the substructure 1 of a floating offshore wind power generation system. [Figure 11] (a) to (c) are diagrams showing the construction process of the lower deck slab 9. [Figure 12] (a) and (b) are diagrams showing the construction process of the cylindrical structure 7. [Figure 13] (a) to (c) are diagrams showing section G in Figure 12(b), illustrating the structure of the joint between the cylindrical structure 7 and the lower floor slab 9. [Figure 14] (a) and (b) are diagrams showing the structure of other joints between the cylindrical structure 7 and the lower floor slab 9. [Figure 15] (a) and (b) are diagrams showing the construction process of the upper floor slab 5. [Figure 16] (a) and (b) are diagrams showing other construction processes for the upper deck 5. [Figure 17] (a) and (b) are diagrams showing the connection structure between the transition piece 13 and the central reinforcing structure 19a. [Figure 18] (a) and (b) are diagrams showing other connection structures between the transition piece 13 and the central reinforcing structure 19a. [Figure 19] (a) and (b) are diagrams showing other connection structures between the transition piece 13 and the central reinforcing structure 19a. [Figure 20] (a) is a diagram showing another connection structure between the transition piece 13 and the central reinforcing structure 19a, and (b) is a diagram showing the circumferential tensioning member 35c. [Modes for carrying out the invention] 【0039】 The embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 shows the floating offshore wind power generation substructure 1 in use. The floating offshore wind power generation substructure 1 is a semi-submersible floating structure for supporting the wind power generation device 3 while floating on the sea. The floating offshore wind power generation substructure 1 has a width greater than its height. With the floating offshore wind power generation substructure 1 floating on the sea, the tower of the wind power generation device 3 is attached above the upper deck 5 of the floating offshore wind power generation substructure 1. 【0040】 In this embodiment, as described above, the tower of the wind turbine 3, including the transition piece 13, is mounted above the upper deck 5 of the floating offshore wind power generation substructure 1. In this case, it is desirable for stability that the tower (transition piece 13) of the wind turbine 3 be positioned approximately in the center of the upper deck 5, but eccentric positioning to the side can be adjusted with ballast or the like. The upper deck 5 is exposed above sea level, for example, and mooring ropes 11 are connected to it. That is, the floating offshore wind power generation substructure 1 is moored to the seabed by mooring ropes 11. 【0041】 Figure 2(a) is a front view showing the substructure 1 for floating offshore wind power generation, and Figure 2(b) is a cross-sectional view taken along line AA of Figure 2(a). The substructure 1 for floating offshore wind power generation is mainly composed of cylindrical structures 7, an upper deck 5, a lower deck 9, etc. The lower deck 9 is joined to the lower ends of multiple hollow cylindrical structures 7, and the upper deck 5 is joined to the upper part. That is, the multiple cylindrical structures 7 are fixed by the upper deck 5 and the lower deck 9, and a sealed space is formed inside the cylindrical structures 7. As mentioned above, the tower of the wind power generation device 3 is attached to the upper deck 5. 【0042】 The cylindrical structure 7 may be constructed using a single method involving reinforcing bars, formwork, and on-site concrete casting, but it is preferable that it be constructed by connecting multiple segments or ring members in the longitudinal direction, which allows for faster construction. The manufacturing method of the cylindrical structure 7 will be described in detail later. In the illustrated example, three cylindrical structures 7 are shown side by side, but this is not the only option. For example, there may be four or more cylindrical structures 7. 【0043】 Furthermore, it is desirable that the lower deck slab 9 extends outward beyond the outermost periphery of the cylindrical structure 7. In this way, by allowing at least a portion of the lower deck slab 9 to extend outward beyond the cylindrical structure 7 in a plan view, this protruding portion acts as resistance to oscillation when the floating offshore wind power generation substructure 1 is floating on the sea, thereby suppressing oscillation. For this reason, for example, the size of the lower deck slab 9 may be larger than the size of the upper deck slab 5. 【0044】 Here, as shown in Figure 2(b), it is desirable that the multiple cylindrical structures 7 be arranged with gaps between them. By creating gaps between the multiple cylindrical structures 7 in this way, waves can pass through the gaps, and the wave force acting from the side can be suppressed. 【0045】 Alternatively, the cylindrical structures 7 may be connected by walls. Figure 3(a) is a front view showing another floating offshore wind power generation substructure 1, and Figure 3(b) is a cross-sectional view of Figure 3(a) along line BB. In the example shown in Figure 3, multiple cylindrical structures 7 are connected by reinforcing walls 15. That is, no gaps are formed between the multiple cylindrical structures 7 that allow waves to pass through. In this case, the space enclosed by the reinforcing walls 15 also functions as a floating structure, and the reinforcing walls 15 function as a reinforcing structure for the upper deck 5 and lower deck 9. In particular, the joints between the upper deck 5 and lower deck 9 and the cylindrical structures 7 can be reinforced by the reinforcing walls 15. Thus, gaps do not necessarily need to be formed between the cylindrical structures 7. Also, some penetrations may be provided to allow waves to pass through. 【0046】 Furthermore, other reinforcing structures may be provided between the cylindrical structures 7. Figure 4(a) is a front view showing another floating offshore wind power generation substructure 1, and Figure 4(b) is a cross-sectional view along line CC of Figure 4(a). In the example shown in Figure 4, reinforcing structures 17 are provided between the cylindrical structures 7, on the upper deck 5 and the lower deck 9. Since the reinforcing structures 17 are formed only on the upper and lower parts of the cylindrical structures 7, gaps can be formed between multiple cylindrical structures 7, allowing waves to pass through the gaps. In this way, by forming the reinforcing structures 17 near the joints between the upper deck 5 and the lower deck 9 and the cylindrical structures 7, it is possible to improve the strength of the joints between the upper deck 5 and the lower deck 9 and the cylindrical structures 7, while simultaneously suppressing the effects of waves. The reinforcing structures 17 may be formed integrally with the upper deck 5 and the lower deck 9, or they may be formed as separate members and joined to the upper deck 5 and the lower deck 9. Furthermore, by joining the reinforcing structure 17 to the cylindrical structure 7, even greater strength can be achieved. 【0047】 Furthermore, other reinforcing structures may be provided between the cylindrical structures 7. In the examples shown in Figures 5(a) and 5(b), reinforcing structures 17a, which are diagonal braces, are placed between the cylindrical structures 7. More specifically, in Figure 5(a), the reinforcing structures 17a are placed diagonally across the space between the cylindrical structures 7, and in Figure 5(b), the reinforcing structures 17a are placed in an inverted V-shape (or V-shape). In the examples shown in Figures 5(a) and 5(b), the reinforcing structures 17a are fixed to the upper floor slab 5 or the lower floor slab 9, but as shown in Figure 5(c), the reinforcing structures 17a may be fixed to the cylindrical structures 7, or to both. Also, the reinforcing structures 17a do not have to be in the form shown, but in any form, a gap can be formed between the multiple cylindrical structures 7, so that waves can pass through the gap. 【0048】 Furthermore, a reinforcing structure may be provided below the approximate center of the upper deck 5. Figure 6(a) is a front view showing another floating offshore wind power generation substructure 1, and Figure 6(b) is a cross-sectional view taken along the DD line of Figure 6(a). In the example shown in Figure 6, a central reinforcing structure 19 is positioned below the approximate center of the upper deck 5. The central reinforcing structure 19 is a wall-like portion formed from each cylindrical structure 7 toward the center. As mentioned above, it is desirable that the lower part of the tower (not shown) of the wind power generation device 3 be positioned approximately in the center of the upper deck 5. In this case, a large moment and horizontal force are applied to the joint between the tower of the wind power generation device 3 and the upper deck 5. In contrast, by providing a central reinforcing structure 19 below the tower of the wind power generation device 3 and below the upper deck 5, the approximate center of the upper deck 5 can be reinforced. 【0049】 Furthermore, the central reinforcing structure provided below the approximate center of the upper deck 5 is not limited to the form shown in Figure 6. Figure 7(a) is a front view showing another floating offshore wind power generation substructure 1, and Figure 7(b) is a cross-sectional view along line EE of Figure 7(a). In the example shown in Figure 7, the central reinforcing structure 19a is provided below the tower of the wind power generation device 3 and below the upper deck 5. The central reinforcing structure 19a has a similar structure to the cylindrical structure 7 positioned between the upper deck 5 and the lower deck 9. That is, one more cylindrical structure 7 is installed approximately in the center of the three cylindrical structures 7. In this case, the tower of the wind power generation device 3 and the central reinforcing structure 19a are continuous via the upper deck 5, but the force received from the tower of the wind power generation device 3 is first received by the upper deck 5, and a portion of the force received by the upper deck 5 is further transmitted to the lower deck 9 by the central reinforcing structure 19a. In this way, the upper slab 5 and the lower slab 9 are connected by the central reinforcing structure 19a, so that both the upper slab 5 and the lower slab 9 can withstand loads from above. Furthermore, a gap can be formed between the cylindrical structure 7 and the central reinforcing structure 19a (the central cylindrical structure 7), allowing waves to pass through the gap. Reinforcing structures as shown in Figures 3 to 6 may also be provided between the cylindrical structure 7 and the central reinforcing structure 19a (the central cylindrical structure 7). 【0050】 Figure 8(a) is a front view showing another floating offshore wind turbine substructure 1, and Figure 8(b) is a cross-sectional view taken along line II of Figure 8(a). In the example shown in Figure 8, a central reinforcing structure 19a is provided below the tower of the wind turbine 3, at the bottom of the upper deck 5, and a reinforcing structure 17 is provided on the lower surface of the upper deck 5 so as to connect the central reinforcing structure 19a and the cylindrical structures 7. That is, one more cylindrical structure 7 is installed approximately in the center of the three cylindrical structures 7, and these are connected by the surrounding reinforcing structure 17. In this way, the approximately central part of the upper deck 5 and the lower deck 9 is connected by the central reinforcing structure 19a, and the upper deck 5 around it is reinforced by the reinforcing structure 17, so that a portion of the force generated by the tower's moment can be more efficiently relieved to the outer cylindrical structures 7. To ensure even higher strength, the diameter of the central reinforcing structure 19a may be made larger than that of the other cylindrical structures 7, as shown in Figure 8(c). Furthermore, the thickness of the central reinforcing structure 19a may be made thicker than that of the other cylindrical structures 7. By doing so, it becomes possible to increase the number of tension members or increase the diameter of the tension members placed in the central reinforcing structure 19a, which will be described later. In this way, depending on the magnitude of the bending moment of the tower, higher strength can be ensured by appropriately selecting or combining reinforcement with the reinforcing structure 17 to the upper floor slab 5, increasing the diameter and thickness of the central reinforcing structure 19a, changing the material, number, and diameter of the tension members, and adding beams and diagonal members as needed. 【0051】 Furthermore, the shapes of the upper slab 5 and the lower slab 9 are not limited to the embodiments described above. In the examples shown in Figures 9(a) and 9(b), a constriction 21 is formed on the outer shape of the lower slab 9 in a plan view. The upper slab 5 can also have a similar shape. That is, the lower slab 9 and the upper slab 5 have a shape that can accommodate a plurality of cylindrical structures 7, and a constriction shape is formed between the cylindrical structures 7 with respect to a straight line (F in the figure) connecting the outer edges near the joint with the cylindrical structures 7. As shown in Figure 9(a), the width of the connection between the cylindrical structure 7 and the central reinforcing structure 19a may be narrower than the outer circumference of the cylindrical structure 7, or as shown in Figure 9(b), the width of the outer circumference of the cylindrical structure 7 and the width of the connection between the cylindrical structure 7 and the central reinforcing structure 19a may be approximately equal. Furthermore, as mentioned above, when the size of the lower slab 9 is made larger than the size of the upper slab 5, the lower slab 9 and the upper slab 5 may have the same external shape but differ only in size, or the upper slab 5 may be in the form shown in Figure 9(a) and the lower slab 9 may be in the form shown in Figure 9(b). By forming the constriction 21 in this way, for example, when installing the tower of the wind turbine 3 approximately in the center of the upper slab 5, interference between the crane boom and the upper slab 5 can be suppressed. Furthermore, although not shown in the diagram, it is possible to reduce weight while ensuring the required strength by partially hollowing out the upper and lower floor slabs. To hollow out or reduce weight, a hollow space or an embedded material such as expanded polystyrene, called a void, can be installed before pouring the concrete. 【0052】 Next, the construction method for the floating offshore wind turbine substructure 1 will be described. The cylindrical structure 7, upper deck 5, and lower deck 9 may be made of concrete or steel, but in the following description, each component will be assumed to be made of prestressed concrete. Furthermore, the floating offshore wind turbine substructure 1 may take any of the forms shown in Figures 2 to 9, but the example shown in Figure 9(b) will be used for the explanation. 【0053】 Figure 10 shows the manufacturing process of the substructure 1 for floating offshore wind power generation. Note that the internal reinforcement bars and other components of each member are not shown in the following explanation. The substructure 1 for floating offshore wind power generation is manufactured at the floating structure manufacturing yard 23 near the quay 25. 【0054】 First, at the construction site of the lower deck 9 in the floating structure fabrication yard 23 near the quay 25, the lower deck 9 is constructed on top of a moving mechanism (not shown). For example, a multi-axle trolley or air casters can be used as the moving mechanism. Next, the lower deck 9 is moved to the construction site of the cylindrical structure 7, where the cylindrical structure 7 (hereinafter including the central reinforcing structure 19a, which has a similar structure to the cylindrical structure 7) is installed on top of the lower deck 9. Furthermore, the lower deck 9 is moved to the construction site of the upper deck 5, where the upper deck 5 is installed on top of the cylindrical structure 7. At this time, vertical prestress is applied to the cylindrical structure 7 between the lower deck 9 and the upper deck 5. This completes the floating offshore wind power generation substructure 1. Alternatively, a transition piece may be installed, and prestress may be applied including this (not shown). 【0055】 In this way, at the floating structure manufacturing yard 23, multiple processes can be carried out in parallel by moving the moving mechanism between at least some of the processes. The completed floating offshore wind power generation substructure 1 is moved onto the semi-submersible barge 27. After being moved onto the semi-submersible barge 27, the substructure is transferred from the moving mechanism to the mounting frame, and the moving mechanism is moved ashore. The semi-submersible barge 27 is towed to the required water depth, sunk by ballast water injection, and the floating offshore wind power generation substructure 1 is detached. The wind power generation equipment 3 and the like are then installed on the upper deck 5 on the semi-submersible barge 27. After that, the semi-submersible barge 27 is sunk at the required water depth, detaching the floating offshore wind power generation substructure 1 and the like from the semi-submersible barge 27, towing it to the installation site, and installing the wind power generation equipment 3 at the installation site. Generally, the installation location for the wind turbine 3, etc., requires a large yard and a large crane on the quay side, and is therefore separate from the floating structure manufacturing yard 23. Alternatively, the wind turbine 3, etc., may be installed after the floating offshore wind power generation substructure 1, etc., has been detached from the semi-submersible barge 27. 【0056】 Next, we will explain each process in more detail. Figure 11 shows an example of a construction method for the lower floor slab 9. As mentioned above, when the lower floor slab 9 becomes large, it becomes difficult to construct it as a single unit. For this reason, as shown in Figure 11(a), a method may be adopted in which multiple segmented floor slabs 29 are pre-constructed as precast materials and then integrated. 【0057】 More specifically, first, the embedded bottom frame and steel side frame (or embedded side frame) are installed, and after installing the internal reinforcement (including anchoring material 31a and anchoring reinforcement 31b), concrete is poured. After the curing period, the steel side frame can be removed and each segmented floor slab 29 can be constructed. The anchoring material 31a protrudes from the upper surface of each segmented floor slab 29 and functions as an anchoring part for the tensioning material at the joint with the cylindrical structure 7, which will be described later. The anchoring reinforcement 31b protrudes in the direction of joining the segmented floor slabs 29 together and functions as a joint when joining the segmented floor slabs 29 together. Note that instead of the anchoring material 31a protruding from the upper surface of each segmented floor slab 29, a hole is made and a trapezoidal or other fitting structure is provided to facilitate positioning and assembly. 【0058】 Next, each segmented floor slab 29 is placed on the moving mechanism, and filler concrete 33 is poured between each segmented floor slab 29 to integrate the multiple segmented floor slabs 29. At this time, as shown in Figure 11(c), tensioning members 35 can be placed in the sheath pipes arranged inside and prestress can be applied by tensioning and anchoring them from, for example, three directions. Note that the segmented form of the lower floor slab 9 is not limited to the illustrated example. Also, the arrangement of the tensioning members 35 is not limited to the illustrated example. 【0059】 Figure 12(a) shows the process of constructing the cylindrical structure 7 above the obtained lower slab 9. As mentioned above, the cylindrical structure 7 is constructed by connecting a plurality of ring members 37 in the longitudinal direction (vertical direction). In this case, water-stopping members or interlocking structures to prevent shearing may be provided between the ring members 37. In addition, tensioning members may be placed in the circumferential direction in advance to apply prestress to the ring members 37. The construction of the cylindrical structure 7 is completed by connecting all the ring members 37. The ring members 37 may be made of prestressed concrete that is integrally formed into a ring shape, or they may be made into a ring shape by connecting multiple segments that are divided in the circumferential direction in the circumferential direction. 【0060】 Figure 13(a) is a cross-sectional view of section G in Figure 12(b), and is a schematic diagram showing the structure of the joint between the lower floor slab 9 and the cylindrical structure 7. As mentioned above, anchoring members 31a are embedded in the lower floor slab 9 at predetermined intervals in the circular circumferential direction. In addition, a space is formed in the lower part of the cylindrical structure 7 (the lowest ring member 37), and a coupler 41 that connects the anchoring members 31a and the tensioning members 35a is housed there. The tensioning members 35a are tensioned and anchored above the cylindrical structure 7, thereby applying prestress to the cylindrical structure 7. The coupler 41 and its space may be provided on the lower floor slab 9 side instead of the lower part of the cylindrical structure 7 (the lowest ring member 37 side), in which case the protrusion of the anchoring members 31a on the lower floor slab 9 will be eliminated when the ring member 37 is installed. 【0061】 As shown in Figure 12(b), instead of embedding the anchoring material 31a in the lower slab 9, a box-shaped opening 39 may be provided below the lower slab 9 to anchor the anchoring material 31a. With this method, by installing the anchoring material 31a from below, it is possible to eliminate the protrusion of the anchoring material 31a on the lower slab 9 when installing the ring member 37. Furthermore, to facilitate the anchoring work, the box-shaped opening 39 may be formed from the upper side of the lower slab 9, allowing the anchoring work to be performed above the lower slab 9. 【0062】 Furthermore, Figure 13(a) is a plan view of the cylindrical structure 7, and Figure 13(b) is a cross-sectional view of the HH line in Figure 13(a) (unfolded view of the cylindrical structure 7). As shown in Figure 13, instead of fixing the tensioning member 35a to the lower floor slab 9, the tensioning member 35a may be passed through the lower floor slab 9 in a roughly U-shape and both ends may be tensioned and then fixed above the cylindrical structure 7. 【0063】 Next, the upper floor slab 5 is placed above the cylindrical structure 7. Figures 15(a) and 15(b) show a method for installing the upper floor slab 5 above the cylindrical structure 7. The upper floor slab 5 is constructed on a movable mechanism 43a on an adjacent platform 49. The upper floor slab 5 may be divided into multiple parts and then integrated, for example, similar to the lower floor slab 9. Here, the platform 49 is positioned to the side of the direction of movement of the lower floor slab 9, etc. (the direction of movement of the movable mechanism 43 that moves the lower floor slab 9, etc.). That is, the movable mechanism 43a can move in a direction approximately perpendicular to the movable mechanism 43. Therefore, the movable mechanism 43a can be used to move the upper floor slab 5 on the platform 49 horizontally above the cylindrical structure 7. 【0064】 Furthermore, instead of constructing the upper slab 5 in advance and then placing it above the cylindrical structure 7, the upper slab 5 may be constructed above the cylindrical structure 7. Figures 16(a) and 16(b) show a method for constructing the upper slab 5 above the cylindrical structure 7. In this case, for example, as shown in Figure 15, the embedded formwork 45 (embedded bottom frame and embedded side frame) may be placed above the cylindrical structure 7, and the upper slab 5 may be constructed by placing reinforcing bars etc. in the embedded formwork 45 and pouring concrete. That is, the embedded formwork 45 of the upper slab 5 can be moved and placed above the cylindrical structure 7 by the moving mechanism 43a, and the upper slab 5 can be constructed by pouring concrete into the embedded formwork 45. 【0065】 As mentioned above, the lower slab 9 and the cylindrical structure 7 are prestressed by a tensioning member 35a that tensions them together in the longitudinal direction. In this case, the upper part of the tensioning member 35a may be anchored to the upper slab 5. In addition, the central cylindrical structure 7 (central reinforcing structure 19a) may also serve to fix the upper wind power generation tower (transition piece). 【0066】 Figure 17(a) is a schematic diagram showing an example of the fixing structure of the transition piece 13. In the following embodiments, examples are shown in which the tensioning member 35a is fixed to the lower floor slab 9, but the fixing method may be any of the forms shown in Figures 13(a) to 13(c), or the tensioning member 35a may be arranged as shown in Figure 14. 【0067】 In the example shown in Figure 17(a), the tensioning member 35a penetrates the upper floor slab 5 and is anchored to the transition piece 13. That is, the transition piece 13 is fixed to the upper floor slab 5 by the tensioning member 35a. This makes it easier to fix the transition piece 13. 【0068】 Furthermore, as shown in Figure 17(b), a thicker reinforced section 47 may be provided at the joint between the central reinforcing structure 19a and the upper floor slab 5. For example, as a ring member constituting the central reinforcing structure 19a, the uppermost ring member may be made thicker by increasing its outer diameter while keeping its inner diameter the same as the other ring members. In this case, a tension member 35b can be placed in the reinforced section 47, spanning both the reinforced section 47 and the upper floor slab 5. In this case, since the tension member 35b is placed outside the tension member 35a, workability is improved. 【0069】 Furthermore, a thicker reinforced section 47 may also be provided at the joint between the central reinforcing structure 19a and the lower floor slab 9. For example, as a ring member constituting the central reinforcing structure 19a, the lowest ring member may be made thicker by increasing its outer diameter while keeping its inner diameter the same as the other ring members. In this case, a tension member 35b can be placed in the thickened section 47, spanning both the thickened section 47 and the lower floor slab 9. 【0070】 In the illustrated example, a thickened section 47 is provided for the central reinforcing structure 19a, but this can also be applied to cylindrical structures 7 other than the central reinforcing structure 19a. That is, for a cylindrical structure 7 made of prestressed concrete, a thickened section 47 may be provided at the joint with the upper slab 5 or lower slab 9, and tensioning members may be placed in the thickened section 47, spanning both the thickened section 47 and the upper slab 5 or lower slab 9. 【0071】 Furthermore, the shape of the thickened portion 47 is not limited to the example shown in Figure 17(b). Figure 18(a) shows an example in which the thickened portion 47 is formed inside the central reinforcing structure 19a. The following explanation will describe an example for the central reinforcing structure 19a, but it can be similarly applied to other cylindrical structures 7. In this case, the uppermost and lowermost ring members constituting the central reinforcing structure 19a may be made thicker by reducing their inner diameter while keeping their outer diameter the same as the other ring members. By doing so, no steps are formed on the outer surface of the central reinforcing structure 19a, thus reducing the resistance to waves and other elements, and making it possible to strengthen the structure by making the length between the reinforcing parts inside the cylinder as short as possible. 【0072】 Furthermore, as shown in Figure 18(b), the thickened portion 47 may be formed on both the inside and outside of the central reinforcing structure 19a. In this case, the uppermost and lowermost ring members constituting the central reinforcing structure 19a may have a larger outer diameter and a smaller inner diameter than the other ring members, making them thicker. This further increases the strength of the central reinforcing structure 19a in the upper and lower sections. 【0073】 In the example described above, the thickened portion was formed by increasing the thickness of the ring member, but this is not the only way. For example, as shown in Figure 19(a), a ring-shaped thickened portion 47a may be formed on the lower slab 9 and the upper slab 5. In this case, the central reinforcing structure 19a is placed on the thickened portion 47a formed on the upper surface of the lower slab 9, and the thickened portion 47a is formed on the upper surface of the upper slab 5 in the area corresponding to the central reinforcing structure 19a. The transition piece 13 is placed and fixed on the thickened portion 47a of the upper slab 5. 【0074】 Alternatively, as shown in Figure 19(b), thickened sections 47 may be formed above and below the central reinforcing structure 19a, and ring-shaped thickened sections 47a may be formed on the lower floor slab 9 and the upper floor slab 5. In this case, the tensioning member 35b is positioned and fixed so as to penetrate the thickened sections 47 and 47a. 【0075】 Furthermore, as shown in Figure 20(a), circumferential tension members 35c may be placed in the thickened portion 47. In this case, as shown in Figure 20(b), the three tension members 35c may be placed with a staggered position in the circumferential direction. For example, one tension member 35c may be placed around 2 / 3 of the circumference, and the three tension members 35c may be placed with a staggered position of 1 / 3 of the circumference and then fixed in place. Note that the fixing positions of the tension members 35c are not limited to the illustrated examples, and each tension member 35c may be placed around the entire circumference. 【0076】 As described above, according to this embodiment, since the cylindrical structure 7 is composed of multiple ring members 37, even large cylindrical structures 7 can be easily constructed. Furthermore, even if the wind power generation device 3 is made larger, it can be accommodated by changing the length and number of cylindrical structures 7. 【0077】 In this configuration, instead of a conventional beam structure, a cylindrical structure 7 is sandwiched between the lower slab 9 and the upper slab 5. By attaching the tower for the wind turbine 3 (including the transition piece 13) to the upper slab 5, the moment and horizontal force from the tower can be received by the upper slab 5. Therefore, compared to the case where the moment and horizontal force are directly received by the lower slab 9, the distance from the top of the tower can be shortened, and the moment can be reduced. 【0078】 In this case, by providing reinforcing structures between the upper floor slab 5 and the lower floor slab 9 between the cylindrical structures 7, the joint strength at the connection between the upper floor slab 5 and the lower floor slab 9 and the cylindrical structures 7 can be increased. 【0079】 Furthermore, by positioning the tower for the wind turbine 3 approximately in the center of the upper deck 5, it becomes easier to maintain balance even if the substructure is enlarged, and adjustments to the attitude and draft using ballast become easier. In this case, by providing central reinforcing structures 19 and 19a below the tower and at the bottom of the upper deck 5, higher strength can be ensured against forces acting on the tower. 【0080】 Furthermore, when the cylindrical structure 7 is made of prestressed concrete, thicker sections 47, 47a are provided at the joint between the central reinforcing structure 19a and the upper or lower floor slab 5 or lower floor slab 9. By placing tensioning members 35b across the thicker sections 47, 47a and the upper or lower floor slab 5 or lower floor slab 9, the joint strength between the central reinforcing structure 19a and the upper or lower floor slab 5 or lower floor slab 9 can be further increased. 【0081】 Furthermore, by deliberately leaving gaps between the multiple cylindrical structures 7, waves can pass through the gaps between the cylindrical structures 7. This makes it possible to suppress the wave force acting on the floating offshore wind power generation substructure 1. 【0082】 Furthermore, by making the size of the lower deck 9 larger than the size of the upper deck 5, the lower deck 9 in the sea can function as a motion suppression mechanism for the floating offshore wind power generation substructure 1. 【0083】 Although embodiments of the present invention have been described above with reference to the attached drawings, the technical scope of the present invention is not limited to the embodiments described above. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these will naturally also fall within the technical scope of the present invention. 【0084】 For example, it goes without saying that the configurations in each embodiment can be combined with each other. [Explanation of symbols] 【0085】 1. Substructure for floating offshore wind power generation 3... Wind power generation equipment 5……Upper floor version 7. Cylindrical structure 9……Subfloor version 11……Mooring rope 13… Transition piece 15… Reinforced wall 17, 17a……Reinforcement structure 19, 19a... Central reinforcement structure 21... Waist 23... Floating structure manufacturing yard 25... Wharf 27……Semi-submersible barge 29……Divided floor slab 31a…Fixing agent 31b... Reinforcement bars 33... Filling concrete 35, 35a, 35b, 35c……Tension material 37... Ring component 39... Box removed 41... Coupler 43, 43a……Movement mechanism 45... Buried formwork 47, 47a……Thickened part 49... Platform
Claims
[Claim 1] A floating offshore wind turbine substructure whose overall width is greater than its overall height, The upper deck to which the tower for the wind turbine is attached, Multiple hollow cylindrical structures joined to the lower part of the upper floor slab, A lower floor plate joined to the lower end of multiple cylindrical structures, It is equipped with, The lower deck slab, in a plan view, protrudes outward from the outermost periphery of the cylindrical structure, and the protruding portion is larger than the portion of the upper deck slab that protrudes outward from the outermost periphery of the cylindrical structure, characterized in that it is a substructure for a floating offshore wind power generation system. [Claim 2] A floating offshore wind turbine substructure having a width greater than its height, The upper deck to which the tower for the wind turbine is attached, Multiple hollow cylindrical structures joined to the lower part of the upper floor slab, A lower floor plate joined to the lower end of multiple cylindrical structures, It is equipped with, The cylindrical structure is made of prestressed concrete, and at the joint between the cylindrical structure and the upper or lower floor slab, a thickened section is provided, and the thickened section has an inner diameter approximately equal to that of the other parts, but a larger outer diameter, thus making it thicker. The substructure for a floating offshore wind power generation system is characterized in that a tensioning member is arranged across the thickened portion and the upper or lower deck. [Claim 3] A floating offshore wind turbine substructure having a width greater than its height, The upper deck to which the tower for the wind turbine is attached, Multiple hollow cylindrical structures joined to the lower part of the upper floor slab, A lower floor plate joined to the lower end of multiple cylindrical structures, It is equipped with, The cylindrical structure is made of prestressed concrete, and at the joint between the cylindrical structure and the upper or lower floor slab, a thickened section is provided, and the thickened section is thicker than the other parts by having an outer diameter approximately equal to that of the other parts and an inner diameter smaller. The substructure for a floating offshore wind power generation system is characterized in that a tensioning member is arranged across the thickened portion and the upper or lower deck. [Claim 4] A floating offshore wind turbine substructure having a width greater than its height, The upper deck to which the tower for the wind turbine is attached, Multiple hollow cylindrical structures joined to the lower part of the upper floor slab, A lower floor plate joined to the lower end of multiple cylindrical structures, It is equipped with, A gap is formed between the multiple cylindrical structures through which waves can pass, The tower for the wind power generation device is positioned approximately in the center of the upper deck. Below the tower for the wind power generation device, a central reinforcing structure is provided at the lower part of the upper deck. The central reinforcing structure is a cylindrical structure positioned between the upper deck and the lower deck, and the central reinforcing structure is characterized in that its strength is increased by an enlarged diameter or increased thickness compared to the other cylindrical structures. This is a substructure for a floating offshore wind power generation system. [Claim 5] A floating offshore wind turbine substructure having a width greater than its height, The upper deck to which the tower for the wind turbine is attached, Multiple hollow cylindrical structures joined to the lower part of the upper floor slab, A lower floor plate joined to the lower end of multiple cylindrical structures, It is equipped with, A substructure for a floating offshore wind power generation system, characterized in that, between the cylindrical structures, a reinforcing structure is continuously provided so as to connect the cylindrical structures, at least near the joint between the lower surface of the upper deck and the cylindrical structure. [Claim 6] The substructure for a floating offshore wind power generation system according to claim 5, wherein the reinforcing structure is a reinforcing wall that extends from the upper deck to the lower deck, and the space enclosed by the reinforcing wall functions as a floating body. [Claim 7] The substructure for a floating offshore wind power generation system according to claim 5, characterized in that the reinforcing structure is a reinforcing wall that is continuous from the upper deck to the lower deck and has a penetration portion for wave passage in a part thereof. [Claim 8] The lower deck and the upper deck have a shape capable of encompassing a plurality of the cylindrical structures, and a constricted shape is formed between the cylindrical structures with respect to a straight line connecting the outer edges near the joints with the cylindrical structures, as described in claim 1 for the floating offshore wind power generation substructure. [Claim 9] The lower structure for a floating offshore wind power generation system according to claim 1, characterized in that the cylindrical structure is composed of a plurality of ring members connected in the longitudinal direction. [Claim 10] The overall width is greater than the overall height, The upper deck to which the tower for the wind turbine is attached, Multiple hollow cylindrical structures joined to the lower part of the upper floor slab, A lower floor plate joined to the lower end of multiple cylindrical structures, A construction method for a floating offshore wind power generation substructure comprising the following: Step a involves constructing the lower deck on the upper part of the moving mechanism near the quay, Step b includes installing the cylindrical structure on the lower floor slab, Step c of installing the upper floor slab on the cylindrical structure, Step d involves applying prestress to the cylindrical structure between the lower floor slab and the upper floor slab, It is equipped with, A method for constructing a substructure for a floating offshore wind power generation system, characterized in that the moving mechanism is moved during at least a portion of the above-mentioned steps to carry out multiple steps in parallel. [Claim 11] The method for constructing a substructure for a floating offshore wind power generation system according to claim 10, characterized in that in step c, the upper deck on the platform is moved horizontally above the cylindrical structure by another moving mechanism. [Claim 12] The method for constructing a substructure for a floating offshore wind power generation system according to claim 10, characterized in that, in step c, the embedded formwork for the upper deck is moved and positioned above the cylindrical structure by another moving mechanism, and the upper deck is constructed by pouring concrete into the embedded formwork.