Offshore wind power foundation

Abstract

To provide an offshore wind power foundation whose design is easy.SOLUTION: An offshore wind power foundation which supports an offshore wind turbine includes: a cylindrical first steel pipe P1; and a cylindrical second steel pipe P2 connected to the first steel pipe P1 via a contact member C. The central axis of the first steel pipe P1 and the central axis of the second steel pipe P2 substantially coincide when viewed along the longer directions of the first steel pipe P1 and the second steel pipe P2, respectively. The contact member C is sandwiched between an end part of the first steel pipe P1 and an end part of the second steel pipe P2, and a welding seam S of the first steel pipe P1 and a welding seam S of the second steel pipe P2 are not deviated by a predetermined distance or more, in the circumferential direction of the first steel pipe P1 or the second steel pipe P2.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an offshore wind turbine foundation. [Background technology]

[0002] An offshore wind foundation is a structure for installing offshore wind turbines on the sea. For example, Patent Document 1 discloses an offshore structure in which prefabricated steel pipes or processed steel pipes made by bending steel plates into a tubular shape and welding the joints are used for steel pipe piles to be driven into the seabed and for steel pipe columns to be attached to the steel pipe piles. Patent Document 2 discloses an offshore wind power tower in which steel pipes formed by joining curved semi-cylindrical steel members are used as monopiles to be driven into the seabed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-77533 A [Patent Document 2] JP 2011-115829 A Summary of the Invention [Problem to be solved by the invention]

[0004] When multiple steel pipes having welded seams are connected in the axial direction, if a crack occurs in the welded seam of one of the multiple steel pipes, the crack may propagate to the welded seam of the connected steel pipe. In this specification, the welded seam is either a straight seam or a spiral seam. To prevent this, a method is used in which the weld seams of connected steel pipes are shifted in the circumferential direction of the steel pipes. However, when designing offshore wind turbine foundations, there is a problem that the design burden increases when considering the positions of the weld seams.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide an offshore wind turbine foundation that is easy to design. [Means for solving the problem]

[0006] <1> The offshore wind foundation according to aspect 1 of the present invention is an offshore wind foundation that supports an offshore wind turbine, comprising a cylindrical first steel pipe and a cylindrical second steel pipe connected to the first steel pipe via a contact member, the central axis of the first steel pipe and the central axis of the second steel pipe approximately coincide when viewed along the longitudinal direction of each of the first steel pipe and the second steel pipe, the contact member is sandwiched between an end of the first steel pipe and an end of the second steel pipe, and a welded seam, which is either a straight seam or a spiral seam, of the end of the first steel pipe that contacts the contact member and the welded seam of the end of the second steel pipe that contacts the contact member are not shifted by more than a predetermined distance in the circumferential direction of the first steel pipe or the second steel pipe.

[0007] According to the first aspect, the abutment member is sandwiched between the end of the first steel pipe and the end of the second steel pipe. This makes it possible to prevent a crack from propagating to the welded seam of the second steel pipe or the first steel pipe even if a crack occurs in a welded seam, which is either a straight seam or a spiral seam, of the first or second steel pipe. Therefore, in an offshore wind foundation, the positional relationship between the welded seam of the first steel pipe and the welded seam of the second steel pipe can be determined without considering the propagation of a crack in the welded seam. Furthermore, the welded seam of the welded seam of the end of the first steel pipe that contacts the abutment member and the welded seam of the end of the second steel pipe that contacts the abutment member are not shifted by a predetermined distance or more in the circumferential direction of the first or second steel pipe. Therefore, it is possible to prevent an increase in the burden of designing an offshore wind foundation by considering the arrangement of the welded seams. In other words, it is possible to facilitate the design of an offshore wind foundation.

[0008] <2> The offshore wind foundation of aspect 2 of the present invention is the offshore wind foundation of aspect 1, further comprising a cylindrical third steel pipe and a cylindrical fourth steel pipe connected to the third steel pipe, wherein the central axis of the third steel pipe and the central axis of the fourth steel pipe are approximately coincident when viewed along the longitudinal direction of the third steel pipe and the fourth steel pipe, the end of the third steel pipe and the end of the fourth steel pipe are connected without an intervening member, and the weld seam of the third steel pipe and the weld seam of the fourth steel pipe are shifted by a predetermined distance or more in the circumferential direction of the third steel pipe or the fourth steel pipe.

[0009] According to the second aspect, the end of the third steel pipe and the end of the fourth steel pipe are connected without using any member. For this reason, if the weld seam of the third steel pipe and the weld seam of the fourth steel pipe are located at a position (for example, the same position) that is less than a predetermined distance away in the circumferential direction of the third or fourth steel pipe, when a crack occurs in the weld seam of the third or fourth steel pipe, the crack may propagate to the weld seam of the fourth or third steel pipe. Therefore, the weld seam of the third steel pipe and the weld seam of the fourth steel pipe are shifted by a predetermined distance or more in the circumferential direction of the third or fourth steel pipe. As a result, even if the end of the third steel pipe and the end of the fourth steel pipe are connected without using any member, it is possible to prevent a crack that occurs in the weld seam of the third or fourth steel pipe from propagating to the weld seam of the fourth or third steel pipe.

[0010] <3> An offshore wind foundation according to a third aspect of the present invention is the offshore wind foundation according to the first or second aspect, characterized in that the abutment member is a transition piece.

[0011] According to the third aspect, the abutment member is a transition piece. In other words, the transition piece is disposed between the first steel pipe and the second steel pipe. Therefore, even if a crack occurs in the weld seam of the first steel pipe or the second steel pipe, the transition piece can prevent the crack from propagating to the weld seam of the second steel pipe or the first steel pipe.

[0012] <4> An offshore wind foundation according to a fourth aspect of the present invention is the offshore wind foundation according to the third aspect, characterized in that the offshore wind foundation is a jacket structure, the offshore wind foundation further comprises a first leg, the first steel pipe and the second steel pipe are at least a part of the first leg, and the abutment member is a flange of the transition piece.

[0013] According to the fourth aspect, the first steel pipe and the second steel pipe are at least a part of the first leg. The abutting member is a flange of the transition piece. In other words, the first leg is divided into the first steel pipe and the second steel pipe by the flange of the transition piece. This makes it possible to prevent a crack generated in the weld seam of the first steel pipe or the second steel pipe from propagating to the weld seam of the second steel pipe or the first steel pipe, even if the positions of the weld seams of the first steel pipe and the second steel pipe in the first leg are not shifted by a predetermined distance or more. Therefore, in the first leg, the positional relationship between the weld seam of the first steel pipe and the weld seam of the second steel pipe can be determined without considering the propagation of a crack in the weld seam. This makes it possible to easily design the first leg in the vicinity of the flange of the transition piece.

[0014] <5> An offshore wind foundation according to aspect 5 of the present invention is an offshore wind foundation according to any one of aspects 1 to 4, characterized in that the offshore wind foundation is a monopile foundation, the first steel pipe is a tower of the offshore wind turbine, and the second steel pipe is a steel pipe pile of the monopile foundation.

[0015] According to the fifth aspect, the first steel pipe is a tower of an offshore wind turbine. The second steel pipe is a steel pipe pile of a monopile foundation. In other words, the tower of the offshore wind turbine and the steel pipe pile of the monopile foundation are connected via a transition piece. Here, the steel pipe pile of the monopile foundation and the transition piece are joined by grout. Therefore, even if the positions of the weld seams of the tower of the offshore wind turbine and the steel pipe pile are not shifted by a predetermined distance or more in the monopile foundation, a crack that occurs in the weld seam of the tower of the offshore wind turbine or the steel pipe pile does not propagate to the weld seam of the steel pipe pile or the tower of the offshore wind turbine. Therefore, in the monopile foundation, the positional relationship between the weld seam of the tower of the offshore wind turbine and the weld seam of the steel pipe pile can be determined without considering the propagation of cracks in the weld seam. Therefore, the design of the monopile foundation near the transition piece can be facilitated.

[0016] <6> An offshore wind foundation according to aspect 6 of the present invention is an offshore wind foundation according to any one of aspects 2 to 5, characterized in that the offshore wind foundation is a jacket structure, the offshore wind foundation further comprises a second leg or a first brace, and the third steel pipe and the fourth steel pipe are at least a part of the second leg or the first brace.

[0017] According to the sixth aspect, the third steel pipe and the fourth steel pipe are at least a part of the second leg or the first brace. That is, for example, when the third steel pipe and the fourth steel pipe are a part of the second leg, the third steel pipe and the fourth steel pipe are connected in the second leg without any member. When the third steel pipe and the fourth steel pipe are a part of the first brace, the third steel pipe and the fourth steel pipe are connected in the first brace without any member. And, as described above, the weld seam of the third steel pipe and the weld seam of the fourth steel pipe are shifted by a predetermined distance or more in the circumferential direction of the third steel pipe or the fourth steel pipe. Thereby, even if the end of the third steel pipe and the end of the fourth steel pipe are connected in the second leg or the first brace without any member, it is possible to suppress the crack generated in the weld seam of the third steel pipe or the fourth steel pipe from propagating to the weld seam of the fourth steel pipe or the third steel pipe.

[0018] <7> An offshore wind foundation according to aspect 7 of the present invention is an offshore wind foundation according to any one of aspects 1 to 6, characterized in that the offshore wind foundation is a jacket structure, the offshore wind foundation further comprises a third leg and a connecting member that connects a steel pipe pile driven into the seabed to the third leg, the first steel pipe and the second steel pipe are at least a part of the third leg, and the abutment member is a flange of the connecting member.

[0019] According to the seventh aspect, the first steel pipe and the second steel pipe are at least a part of the third leg. The abutting member is a flange of the connection member. In other words, the third leg is divided into the first steel pipe and the second steel pipe by the flange of the connection member. This makes it possible to prevent a crack generated in the weld seam of the first steel pipe or the second steel pipe from propagating to the weld seam of the second steel pipe or the first steel pipe, even if the positions of the weld seams of the first steel pipe and the second steel pipe are not shifted by a predetermined distance or more in the third leg. Therefore, in the third leg, the positional relationship between the weld seam of the first steel pipe and the weld seam of the second steel pipe can be determined without considering the propagation of a crack in the weld seam. This makes it possible to easily design the third leg in the vicinity of the flange of the connection member.

[0020] <8> An offshore wind foundation according to aspect 8 of the present invention is an offshore wind foundation according to any one of aspects 1 to 7, characterized in that the offshore wind foundation is a jacket structure, the offshore wind foundation further comprises a first brace and a second brace, the first steel pipe and the second steel pipe are at least a part of the first brace, and the abutment member is the second brace.

[0021] According to the eighth aspect, the first steel pipe and the second steel pipe are at least a part of the first brace. The abutting member is the second brace. In other words, the first brace is divided into the first steel pipe and the second steel pipe at the boundary of the second brace. This makes it possible to prevent a crack occurring in the weld seam of the first steel pipe or the second steel pipe from propagating to the weld seam of the second steel pipe or the first steel pipe, even if the positions of the weld seams of the first steel pipe and the second steel pipe in the first brace are not shifted by a predetermined distance or more. Therefore, in the first brace, the positional relationship between the weld seam of the first steel pipe and the weld seam of the second steel pipe can be determined without considering the propagation of a crack in the weld seam. This makes it possible to easily design the first brace in the vicinity of the second brace. Effect of the Invention

[0022] According to the present invention, it is possible to provide an offshore wind turbine foundation that is easy to design. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a perspective view of an offshore wind power foundation according to a first embodiment. [Diagram 2] FIG. 2 is a front view of the offshore wind foundation according to the first embodiment. [Diagram 3] FIG. 2 is a schematic diagram of a connection between a first steel pipe and a second steel pipe according to the embodiment. [Figure 4] FIG. 4 is a schematic diagram of a connection between a third steel pipe and a fourth steel pipe according to the embodiment. [Diagram 5] FIG. 11 is a perspective view of an offshore wind power foundation according to a second embodiment. [Figure 6] FIG. 11 is a cross-sectional view of the front view of an offshore wind power foundation according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an offshore wind turbine foundation 100 according to one embodiment of the present invention will be described with reference to the drawings. The offshore wind turbine foundation 100 according to this embodiment is placed on the sea and supports an offshore wind turbine WM. FIG. 1 is a perspective view of an offshore wind power foundation 100 according to the first embodiment. FIG. 2 is a front view of the offshore wind power foundation 100 according to the first embodiment. The offshore wind foundation 100 shown in Figures 1 and 2 includes a transition piece 10, a first steel pipe P1, a second steel pipe P2, a third steel pipe P3, and a fourth steel pipe P4.

[0025] The transition piece 10 is connected to the offshore wind turbine WM. The offshore wind turbine WM is connected to the transition piece 10 by connecting the lower end of the tower T to a center pipe 11 included in the transition piece 10. The center pipe 11 is supported by, for example, an upper plate 12 (flange) and a lower plate 13 (flange) that are further included in the transition piece 10. In addition, the transition piece 10 may further include a reinforcing plate 14 for reinforcing the connection between the center pipe 11, the upper plate 12, and the lower plate 13.

[0026] Here, the tower T and center pipe 11 of the offshore wind turbine WM are both cylindrical members. The cylindrical shapes of the tower T and center pipe 11 of the offshore wind turbine WM are formed by welding together ends of one or more steel plates bent into an arc shape along the longitudinal direction of the cylindrical shapes. For this reason, as shown in Fig. 2, the tower T and center pipe 11 of the offshore wind turbine WM each have a weld seam S. In this embodiment, a straight seam refers to a weld seam formed in each tubular member of the offshore wind power foundation 100 along the direction of the pipe axis. In this embodiment, the spiral seam refers to a welded seam formed in each tubular member of the offshore wind power foundation 100, and formed in a spiral shape around the tube axis. For example, both of the weld seams S in two steel pipes whose ends are connected to each other may be straight seams. Alternatively, both of the weld seams S in which the ends are connected to each other may be spiral seams. Alternatively, one of the weld seams S in which the ends are connected to each other may be a straight seam and the other a spiral seam. Hereinafter, in this embodiment, the description will be given assuming that all the weld seams S are straight seams.

[0027] (Regarding the first steel pipe P1 and the second steel pipe P2) FIG. 3 is a schematic diagram of a connection portion between a first steel pipe and a second steel pipe according to the embodiment. As shown in Fig. 3, the first steel pipe P1 and the second steel pipe P2 are cylindrical steel pipes. The cylindrical shape of the first steel pipe P1 and the second steel pipe P2 is formed by welding together the ends of one or more steel plates that have been bent into an arc shape along the longitudinal direction of the cylindrical shape. Therefore, the first steel pipe P1 and the second steel pipe P2 each have a weld seam S along the longitudinal direction.

[0028] The first steel pipe P1 and the second steel pipe P2 are connected to each other. The central axis of the first steel pipe P1 and the central axis of the second steel pipe P2 are approximately aligned when viewed along the longitudinal direction of each of the first steel pipe P1 and the second steel pipe P2. Note that approximately aligned means that the shortest distance between the central axis of the first steel pipe P1 and the central axis of the second steel pipe P2 is within 10% of the outer diameter of the first steel pipe P1 or the second steel pipe P2.

[0029] Here, if a crack occurs in either the weld seam S of the first steel pipe P1 or the second steel pipe P2, the crack may propagate to the weld seam S of the second steel pipe P2 or the first steel pipe P1. In order to suppress this, for example, a measure may be taken in which the weld seam S of the first steel pipe P1 and the weld seam S of the second steel pipe P2 are positioned at positions shifted by a predetermined distance or more in the circumferential direction of the first steel pipe P1 or the second steel pipe P2. Note that the predetermined distance in the circumferential direction of the first steel pipe P1 or the second steel pipe P2 is, for example, a distance equivalent to 45° in the circumferential direction of the first steel pipe P1 or the second steel pipe P2. However, taking into consideration the arrangement of the weld seam S in the design increases the design burden of the offshore wind foundation 100. In this embodiment, the weld seams S being offset from one another means that the ends of the weld seams S are not connected in a continuous manner but are separated from each other.

[0030] In order to suppress this, in this embodiment, the second steel pipe P2 is connected to the first steel pipe P1 via the abutment member C as shown in FIG. 3. In other words, the abutment member C is arranged so as to be sandwiched between the end of the first steel pipe P1 and the end of the second steel pipe P2. The weld seam S at the end of the first steel pipe P1 that is in contact with the abutment member C and the weld seam S at the end of the second steel pipe P2 that is in contact with the abutment member C are not shifted by a predetermined distance or more in the circumferential direction of the first steel pipe P1 or the second steel pipe P2. Alternatively, the weld seams S may coincide with each other in the circumferential direction of the first steel pipe P1 or the second steel pipe P2. That is, the ends of the weld seams S may be connected in a continuous manner. This makes it easier to design the periphery of the connection between the first steel pipe P1 and the second steel pipe P2. In this embodiment, the contact member C is, for example, a transition piece 10 or the like (details will be described later).

[0031] (Regarding the 3rd Steel Pipe P3 and the 4th Steel Pipe P4) FIG. 4 is a schematic diagram of a connection portion between a third steel pipe and a fourth steel pipe according to the embodiment. As shown in Fig. 4, the third steel pipe P3 and the fourth steel pipe P4 are cylindrical steel pipes. The cylindrical shape of the third steel pipe P3 and the fourth steel pipe P4 is formed by welding together the ends of one or more steel plates that have been bent into an arc shape along the longitudinal direction of the cylindrical shape. Therefore, the third steel pipe P3 and the fourth steel pipe P4 each have a weld seam S along the longitudinal direction.

[0032] The third steel pipe P3 and the fourth steel pipe P4 are connected to each other. The central axis of the third steel pipe P3 and the central axis of the fourth steel pipe P4 are approximately aligned when viewed along the longitudinal direction of each of the third steel pipe P3 and the fourth steel pipe P4. Note that approximately aligned means that the shortest distance between the central axis of the third steel pipe P3 and the central axis of the fourth steel pipe P4 is within 10% of the outer diameter of the third steel pipe P3 or the fourth steel pipe P4.

[0033] Here, if a crack occurs in either the third steel pipe P3 or the weld seam S of the fourth steel pipe P4, the crack may propagate to the fourth steel pipe P4 or the weld seam S of the third steel pipe P3. In order to prevent this, for example, a measure of arranging an abutment member C between the third steel pipe P3 and the fourth steel pipe P4, as in the above-mentioned connection portion between the first steel pipe P1 and the second steel pipe P2, may be taken. However, for example, arranging an abutment member C for the connection portions of each of the other components in the offshore wind foundation 100 may cause a problem of increased costs.

[0034] In order to deal with such a case, the end of the third steel pipe P3 and the end of the fourth steel pipe P4 are connected without any intervening member, as shown in FIG. 4. The weld seam S of the third steel pipe P3 and the weld seam S of the fourth steel pipe P4 are shifted by a predetermined distance or more in the circumferential direction of the third steel pipe P3 or the fourth steel pipe P4. The predetermined distance in the circumferential direction of the third steel pipe P3 or the fourth steel pipe P4 is, for example, a distance equivalent to 45° in the circumferential direction of the third steel pipe P3 or the fourth steel pipe P4. This prevents a crack generated in the weld seam S of the third steel pipe P3 or the fourth steel pipe P4 from propagating to the weld seam S of the fourth steel pipe P4 or the third steel pipe P3.

[0035] (About Offshore Wind Foundation 100) Next, the offshore wind power foundation 100 according to this embodiment will be described. 1 and 2, an offshore wind foundation 100 according to this embodiment is a jacket structure. The offshore wind foundation 100, which is a jacket structure, includes a transition piece 10, a leg 20, a pile 30 (steel pipe pile), a connection member 40, and a brace 50.

[0036] A plurality of legs 20 are provided in the offshore wind foundation 100, which is a jacket structure. In the offshore wind foundation 100 according to this embodiment, four legs 20 are provided as shown in Fig. 1. Hereinafter, the plurality of legs 20 may be referred to as a first leg 21, a second leg 22, a third leg 23, and a fourth leg 24, respectively. The upper ends of the multiple legs 20 are connected to the transition piece 10. The lower ends of the legs 20 are connected to the upper ends of piles 30 driven into the seabed. In this way, the multiple legs 20 support the transition piece 10 above sea level.

[0037] For example, two piles 30 are provided for one leg 20. Therefore, eight piles 30 are provided in the offshore wind foundation 100, which is the jacket structure. The lower end of each of the multiple piles 30 provided as described above is driven into the seabed. The upper end of each of the piles 30 is connected to the leg 20. In this way, the piles 30 support the leg 20 above sea level.

[0038] The connection member 40 connects the pile 30 and the leg 20. The connection member 40 is a so-called skirt sleeve. As shown in Fig. 1, the connection member 40, which is a skirt sleeve, includes a sleeve 41, an upper flange 42 (flange), a lower flange 43 (flange), and a web 44. Note that the above configurations are examples of a skirt sleeve, and any other structure may be used as appropriate. The sleeve 41 is a cylindrical member. The upper ends of the piles 30 are inserted into the sleeve 41. As described above, two piles 30 are provided for one leg 20. Therefore, two sleeves 41 are provided for one leg 20.

[0039] The upper flange 42 is a plate-shaped member that connects an upper portion of the sleeve 41 and the leg 20. The upper flange 42, the sleeve 41, and the leg 20 are connected by, for example, welding. The lower flange 43 is a plate-shaped member that connects a lower portion of the sleeve 41 and the leg 20. The lower flange 43 is connected to the sleeve 41 and the leg 20 by, for example, welding. The web 44 is a plate-like member that reinforces the connections among the leg 20, the sleeve 41, the upper flange 42, and the lower flange 43. That is, for example, the upper end of the web 44 is connected to the upper flange 42 and the lower end is connected to the lower flange 43. Both horizontal ends of the web 44 are connected to the sleeve 41 or the leg 20, respectively. The web 44 is connected to the above-mentioned members by, for example, welding.

[0040] The braces 50 connect adjacent legs 20 in the circumferential direction of the offshore wind foundation 100. The braces 50 are arranged in an X-shape, for example, as shown in Figs. 1 and 2. Hereinafter, one side of the X-shape may be referred to as a first brace 51, and the other side as a second brace 52. That is, the braces 50 include a first brace 51 and a second brace 52.

[0041] (Example of arrangement of the first steel pipe P1 and the second steel pipe P2) Next, an example of the arrangement of the first steel pipe P1 and the second steel pipe P2 in the offshore wind turbine foundation 100 will be described. The first steel pipe P1 and the second steel pipe P2 are, for example, at least a part of the first leg 21, and the abutting member C is the lower plate 13 of the transition piece 10. That is, as shown in FIG. 2, the first leg 21 is divided into the first steel pipe P1 and the second steel pipe P2 by the lower plate 13 of the transition piece 10. In other words, the lower plate 13 of the transition piece 10 is a through member. With this arrangement, a crack generated in the weld seam S of the first steel pipe P1 or the second steel pipe P2 in the portion around the lower plate 13 of the transition piece 10 in the first leg 21 is prevented from propagating to the weld seam S of the second steel pipe P2 or the first steel pipe P1. It should be noted that the same configuration may be applied not only to the first leg 21 but also to the second leg 22, the third leg 23, and the fourth leg 24.

[0042] The first steel pipe P1 and the second steel pipe P2 are, for example, at least a part of the first leg 21, and the abutting member C is the upper flange 42 of the connection member 40. That is, as shown in FIG. 2, the first leg 21 is divided into the first steel pipe P1 and the second steel pipe P2 by the upper flange 42 of the connection member 40. In other words, the upper flange 42 of the connection member 40 is a through member. With this arrangement, a crack generated in the weld seam S of the first steel pipe P1 or the second steel pipe P2 in the portion around the upper flange 42 of the connection member 40 in the first leg 21 is prevented from propagating to the weld seam S of the second steel pipe P2 or the first steel pipe P1. The above-mentioned configuration is not limited to the first leg 21, but may also be applied to the second leg 22, the third leg 23, and the fourth leg 24.

[0043] The first steel pipe P1 and the second steel pipe P2 are, for example, at least a part of the first brace 51, and the abutting member C is the second brace 52. That is, like the upper brace 50 of the braces 50 provided in two stages, one above the other, in the offshore wind foundation 100 shown in FIG. 2, the first brace 51 is divided into the first steel pipe P1 and the second steel pipe P2 at the boundary of the second brace 52. In this case, of the braces 50 forming an X-shape, the second brace 52 is a through member. By adopting such an arrangement, in the first brace 51, a crack generated in the weld seam S of the first steel pipe P1 or the second steel pipe P2 is prevented from propagating to the weld seam S of the second steel pipe P2 or the first steel pipe P1.

[0044] (Example of arrangement of the third steel pipe P3 and the fourth steel pipe P4) Next, an example of the arrangement of the third steel pipe P3 and the fourth steel pipe P4 in the offshore wind turbine foundation 100 will be described. The third steel pipe P3 and the fourth steel pipe P4 are, for example, at least a part of the first leg 21. Specifically, the connection portion between the third steel pipe P3 and the fourth steel pipe P4 is located in a portion of the first leg 21 where the abutment member C is not arranged. That is, for example, as shown in Fig. 2, the third steel pipe P3 is a portion of the first leg 21 other than the leg can, which is a portion to which the brace 50 is connected. The fourth steel pipe P4 is the leg can of the first leg 21. In other words, in the first leg 21, the weld seam S of the portion other than the leg can and the weld seam S of the leg can are shifted by a predetermined distance or more in the circumferential direction of the first leg 21. By adopting such an arrangement, even if the parts of the first leg 21 other than the leg can are connected to the leg can without any intervening member, a crack that occurs in the weld seam S of the third steel pipe P3 or the fourth steel pipe P4 is prevented from propagating to the weld seam S of the fourth steel pipe P4 or the third steel pipe P3. Here, when the length of the first leg 21 exceeds the manufacturable length of the steel pipe forming the first leg 21, a plurality of the steel pipes are joined together to form the first leg 21. The third steel pipe P3 and the fourth steel pipe P4 may each be a plurality of the steel pipes in the above cases. The above-mentioned configuration is not limited to the first leg 21, but may also be applied to the second leg 22, the third leg 23, and the fourth leg 24.

[0045] The third steel pipe P3 and the fourth steel pipe P4 are, for example, at least a part of the first brace 51. Specifically, the connection portion between the third steel pipe P3 and the fourth steel pipe P4 is located in a portion of the first brace 51 where the abutment member C is not arranged. That is, for example, the third steel pipe P3 is a portion of the first brace 51 located below other than the brace can, which is the portion to which the second brace 52 is connected. The fourth steel pipe P4 is the brace can of the first brace 51 located below. In other words, in the first brace 51, the weld seam S of the portion other than the brace can and the weld seam S of the brace can are shifted by a predetermined distance or more in the circumferential direction of the first brace 51. Such an arrangement may be used, for example, in the case of the first brace 51 provided in the upper brace 50 of the offshore wind foundation 100 shown in Fig. 2, where the first brace 51 is divided into a first steel pipe P1 and a second steel pipe P2 by a second brace 52. Alternatively, such an arrangement may be used in the case of the first brace 51 provided in the lower brace 50 of the offshore wind foundation 100, where the first brace 51 is a through member and the second brace 52 is divided into the first steel pipe P1 and the second steel pipe P2 by the first brace 51.

[0046] Here, when the length of the first brace 51 exceeds the manufacturable length of the steel pipe forming the first brace 51, the first brace 51 is formed by connecting a plurality of the steel pipes. The third steel pipe P3 and the fourth steel pipe P4 may each be, for example, a plurality of steel pipes as in the above case. Such an arrangement is preferably used when the first brace 51 is a through member, such as the first brace 51 provided in the brace 50 located on the lower side of the offshore wind foundation 100.

[0047] As described above, according to the offshore wind foundation 100 of this embodiment, the contact member C is sandwiched between the end of the first steel pipe P1 and the end of the second steel pipe P2. This makes it possible to prevent a crack from propagating to the weld seam S of the second steel pipe P2 or the first steel pipe P1 even if a crack occurs in the weld seam S, which is either the weld seam or the spiral seam of the first steel pipe P1 or the second steel pipe P2. Therefore, in the offshore wind foundation 100, the positional relationship between the weld seam S of the first steel pipe P1 and the weld seam S of the second steel pipe P2 can be determined without considering the propagation of a crack in the weld seam S. And, the weld seam S of the end of the first steel pipe P1 that is in contact with the contact member C and the weld seam S of the end of the second steel pipe P2 that is in contact with the contact member C are not shifted by a predetermined distance or more in the circumferential direction of the first steel pipe P1 or the second steel pipe P2. Therefore, it is possible to suppress an increase in the burden of designing the offshore wind power foundation 100 due to consideration of the arrangement of the weld seam S. In other words, the design of the offshore wind power foundation 100 can be made easier.

[0048] Also, the end of the third steel pipe P3 and the end of the fourth steel pipe P4 are connected without any intervening member. For this reason, for example, if the weld seam S of the third steel pipe P3 and the weld seam S of the fourth steel pipe P4 are located at a position (for example, the same position) that is less than a predetermined distance in the circumferential direction of the third steel pipe P3 or the fourth steel pipe P4, when a crack occurs in the weld seam S of the third steel pipe P3 or the fourth steel pipe P4, the crack may propagate to the weld seam S of the fourth steel pipe P4 or the third steel pipe P3. Therefore, the weld seam S of the third steel pipe P3 and the weld seam S of the fourth steel pipe P4 are shifted by a predetermined distance or more in the circumferential direction of the third steel pipe P3 or the fourth steel pipe P4. As a result, even if the end of the third steel pipe P3 and the end of the fourth steel pipe P4 are connected without any intervening component, cracks that occur in the weld seam S of the third steel pipe P3 or the fourth steel pipe P4 can be prevented from propagating to the weld seam S of the fourth steel pipe P4 or the third steel pipe P3.

[0049] Moreover, the abutment member C is a transition piece 10. In other words, the transition piece 10 is disposed between the first steel pipe P1 and the second steel pipe P2. Therefore, even if a crack occurs in the weld seam S of the first steel pipe P1 or the second steel pipe P2, the transition piece 10 can prevent the crack from propagating to the weld seam S of the second steel pipe P2 or the first steel pipe P1.

[0050] Moreover, the first steel pipe P1 and the second steel pipe P2 are at least a part of the first leg 21. The abutting member C is a flange of the transition piece 10. In other words, the first leg 21 is divided into the first steel pipe P1 and the second steel pipe P2 by the flange of the transition piece 10. This makes it possible to prevent a crack generated in the weld seam S of the first steel pipe P1 or the second steel pipe P2 from propagating to the weld seam S of the second steel pipe P2 or the first steel pipe P1, even if the positions of the weld seam S of the first steel pipe P1 and the second steel pipe P2 in the first leg 21 are not shifted by a predetermined distance or more. Therefore, in the first leg 21, the positional relationship between the weld seam S of the first steel pipe P1 and the weld seam S of the second steel pipe P2 can be determined without considering the propagation of a crack in the weld seam S. This makes it possible to facilitate the design of the first leg 21 in the vicinity of the flange of the transition piece 10.

[0051] Moreover, the third steel pipe P3 and the fourth steel pipe P4 are at least a part of the second leg 22 or the first brace 51. That is, for example, when the third steel pipe P3 and the fourth steel pipe P4 are a part of the second leg 22, the third steel pipe P3 and the fourth steel pipe P4 are connected in the second leg 22 without any member. When the third steel pipe P3 and the fourth steel pipe P4 are a part of the first brace 51, the third steel pipe P3 and the fourth steel pipe P4 are connected in the first brace 51 without any member. And, as described above, the weld seam S of the third steel pipe P3 and the weld seam S of the fourth steel pipe P4 are shifted by a predetermined distance or more in the circumferential direction of the third steel pipe P3 or the fourth steel pipe P4. As a result, even if the end of the third steel pipe P3 and the end of the fourth steel pipe P4 are connected in the second leg 22 or the first brace 51 without any intervening component, a crack that occurs in the weld seam S of the third steel pipe P3 or the fourth steel pipe P4 can be prevented from propagating to the weld seam S of the fourth steel pipe P4 or the third steel pipe P3.

[0052] Moreover, the first steel pipe P1 and the second steel pipe P2 are at least a part of the third leg 23. The abutting member C is a flange of the connection member 40. In other words, the third leg 23 is divided into the first steel pipe P1 and the second steel pipe P2 by the flange of the connection member 40. This makes it possible to prevent a crack generated in the weld seam S of the first steel pipe P1 or the second steel pipe P2 from propagating to the weld seam S of the second steel pipe P2 or the first steel pipe P1, even if the positions of the weld seam S of the first steel pipe P1 and the second steel pipe P2 in the third leg 23 are not shifted by a predetermined distance or more. Therefore, in the third leg 23, the positional relationship between the weld seam S of the first steel pipe P1 and the weld seam S of the second steel pipe P2 can be determined without considering the propagation of a crack in the weld seam S. This makes it possible to easily design the third leg 23 in the vicinity of the flange of the connection member 40.

[0053] Moreover, the first steel pipe P1 and the second steel pipe P2 are at least a part of the first brace 51. The abutting member C is the second brace 52. In other words, the first brace 51 is divided into the first steel pipe P1 and the second steel pipe P2 at the boundary of the second brace 52. This makes it possible to prevent a crack occurring in the weld seam S of the first steel pipe P1 or the second steel pipe P2 from propagating to the weld seam S of the second steel pipe P2 or the first steel pipe P1, even if the positions of the weld seam S of the first steel pipe P1 and the second steel pipe P2 in the first brace 51 are not shifted by a predetermined distance or more. Therefore, in the first brace 51, the positional relationship between the weld seam S of the first steel pipe P1 and the weld seam S of the second steel pipe P2 can be determined without considering the propagation of a crack in the weld seam S. This makes it possible to easily design the first brace 51 in the vicinity of the second brace 52.

[0054] Second embodiment Next, a second offshore wind foundation 200 (offshore wind foundation) according to a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and their description will be omitted, with only the differences being described. FIG. 5 is a perspective view of an offshore wind power foundation according to the second embodiment. FIG. 6 is a cross-sectional view of the front view of the offshore wind power foundation according to the second embodiment. The second offshore wind foundation 200 is a monopile foundation, as shown in Figures 5 and 6. The second offshore wind foundation 200, which is a monopile foundation, includes a monopile 210 (steel pipe pile) and a second transition piece 220.

[0055] The lower end of the monopile 210 is driven into the seabed, and the upper end is connected to the second transition piece 220. In this way, the monopile 210 supports the second transition piece 220 on the sea. The monopile 210 is a cylindrical member with a tapered upper portion. That is, as shown in Fig. 6, the lower portion of the monopile 210 is cylindrical, and the upper portion of the monopile 210 has a diameter that decreases from an arbitrary position in the pipe axial direction toward the upper end. The monopile 210 is formed by welding together the ends of one or more steel plates that have been bent into an arc shape along the longitudinal direction of the cylindrical shape. Therefore, the monopile 210 has a weld seam S along the longitudinal direction.

[0056] Here, when the length of the monopile 210 exceeds the manufacturable length of the steel pipes forming the monopile 210, the monopile 210 is formed by joining together a plurality of the steel pipes, as shown in Fig. 6. In this case, the third steel pipe P3 and the fourth steel pipe P4 described in the first embodiment may each be a plurality of steel pipes in the above-mentioned cases. Also, in this case, the third steel pipe P3 may be shaped so that its diameter decreases from the lower end to the upper end, thereby making the upper part of the monopile 210 tapered.

[0057] The second transition piece 220 connects the monopile 210 and the tower T of the offshore wind turbine WM. The second transition piece 220 includes a main body 221 and a second upper plate 222. Main body 221 is a cylindrical member with a tapered lower portion. That is, as shown in Fig. 6, the upper portion of main body 221 is cylindrical, and the lower portion of main body 221 has a diameter that decreases from the lower end toward the top. The monopile 210 is inserted into the main body 221. This connects the second transition piece 220 and the monopile 210. The main body 221 and the monopile 210 are fixed together by grout (not shown). For this reason, it is preferable that the tapered portion of the main body 221 and the tapered portion of the monopile 210 have the same taper angle. The second upper plate 222 is provided at the upper end of the main body 221. The upper surface of the second upper plate 222 abuts against the tower T of the offshore wind turbine WM.

[0058] (Example of arrangement of the first steel pipe P1 and the second steel pipe P2) Next, an example of the arrangement of the first steel pipes P1 and the second steel pipes P2 in the second offshore wind foundation 200 will be described. As shown in FIG. 6, in the second offshore wind foundation 200, the first steel pipe P1 is the tower T of the offshore wind turbine WM, and the second steel pipe P2 is the monopile 210 of the monopile foundation. In the second offshore wind foundation 200, the abutting member C is the second upper plate 222 of the second transition piece 220. That is, the transition piece 10 is disposed between the tower T of the offshore wind turbine WM and the monopile 210. The weld seam S of the tower T of the offshore wind turbine WM and the weld seam S of the monopile 210 are not shifted by a predetermined distance or more in the circumferential direction of the tower T of the offshore wind turbine WM or the monopile 210. By disposing in this way, it is possible to prevent a crack occurring in the weld seam S of the tower T of the offshore wind turbine WM or the monopile 210 from propagating to the weld seam S of the monopile 210 or the tower T of the offshore wind turbine WM.

[0059] As described above, according to the second offshore wind foundation 200 according to the second embodiment, the first steel pipe P1 is the tower T of the offshore wind turbine WM. The second steel pipe P2 is the monopile 210 of the monopile foundation. In other words, the tower T of the offshore wind turbine WM and the monopile 210 of the monopile foundation are connected via the transition piece 10. Here, the steel pipe pile of the monopile foundation and the transition piece are joined by grout. For this reason, in the monopile foundation, even if the positions of the weld seam S of the tower T of the offshore wind turbine WM and the monopile 210 are not shifted by a predetermined distance or more, a crack generated in the tower T of the offshore wind turbine WM or the weld seam S of the monopile 210 does not propagate to the weld seam S of the monopile 210 or the tower T of the offshore wind turbine WM. Therefore, in the monopile foundation, the positional relationship between the weld seam S of the tower T of the offshore wind turbine WM and the weld seam S of the monopile 210 can be determined without considering the propagation of cracks in the weld seam S. This makes it possible to easily design the monopile foundation in the vicinity of the transition piece 10.

[0060] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, when the first steel pipe P1 or the second steel pipe P2 exceeds the manufacturable length of the steel pipe forming the first steel pipe P1 or the second steel pipe P2, the first steel pipe P1 or the second steel pipe P2 may be formed by joining a plurality of the steel pipes together. In this case, it is preferable that the weld seams S of the plurality of steel pipes are shifted by a predetermined distance or more in the circumferential direction of the plurality of steel pipes. In other words, the first steel pipe P1 or the second steel pipe P2 may include a third steel pipe P3 and a fourth steel pipe P4.

[0061] In addition, within the scope of the invention, the components in the above-described embodiments may be replaced with well-known components, and the above-described modified examples may be combined as appropriate. [Explanation of symbols]

[0062] 10 Transition Piece 11 Center pipe 12 Upper plate 13 Lower plate 14 Reinforcement plate Leg 20 21 1st Leg 22 2nd Leg 23 Third Leg 24 4th Leg 30 stakes 40 Connection member 41 Sleeve 42 Upper flange 43 Lower flange 44 Web 50 Brace 51 First Brace 52 Second Brace 100 Offshore Wind Fundamentals 200 2nd Offshore Wind Foundation 210 Monopile 220 Second Transition Piece 221 Main body 222 2nd upper plate C Contact member P1 1st steel pipe P2 2nd steel pipe P3 3rd steel pipe P4 4th steel pipe S Welded seam T Tower WM Offshore Wind Turbine

Claims

1. An offshore wind foundation supporting an offshore wind turbine, comprising: A cylindrical first steel pipe; A cylindrical second steel pipe connected to the first steel pipe via a contact member; Equipped with The central axis of the first steel pipe and the central axis of the second steel pipe are substantially aligned when viewed along the longitudinal direction of each of the first steel pipe and the second steel pipe, The abutment member is sandwiched between an end of the first steel pipe and an end of the second steel pipe, The weld seam, which is either a straight seam or a spiral seam at the end of the first steel pipe that contacts the abutting member, and the weld seam, which is either a straight seam or a spiral seam at the end of the second steel pipe that contacts the abutting member, are not shifted by a predetermined distance or more in the circumferential direction of the first steel pipe or the second steel pipe. An offshore wind power foundation characterized by:

2. A cylindrical third steel pipe; A cylindrical fourth steel pipe connected to the third steel pipe; Further comprising: The central axis of the third steel pipe and the central axis of the fourth steel pipe are substantially aligned when viewed along the longitudinal direction of the third steel pipe and the fourth steel pipe, The end of the third steel pipe and the end of the fourth steel pipe are connected without any member, The weld seam of the third steel pipe and the weld seam of the fourth steel pipe are shifted by a predetermined distance or more in the circumferential direction of the third steel pipe or the fourth steel pipe. The offshore wind foundation according to claim 1 .

3. The abutment member is a transition piece. The offshore wind power foundation according to claim 1 or 2.

4. The offshore wind foundation is a jacket structure, The offshore wind foundation further comprises a first leg, The first steel pipe and the second steel pipe are at least a part of the first leg, The abutment member is a flange of the transition piece. The offshore wind foundation according to claim 3 .

5. The offshore wind foundation is a monopile foundation, the first steel pipe is a tower of the offshore wind turbine, The second steel pipe is a steel pipe pile of the monopile foundation. The offshore wind foundation according to claim 3 .

6. The offshore wind foundation is a jacket structure, The offshore wind foundation further comprises a second leg or a first brace; The third steel pipe and the fourth steel pipe are at least a part of the second leg or the first brace. The offshore wind foundation according to claim 2 .

7. The offshore wind foundation is a jacket structure, The offshore wind foundation further includes a third leg and a connection member that connects a steel pipe pile driven into the seabed to the third leg, The first steel pipe and the second steel pipe are at least a part of the third leg, The abutment member is a flange of the connection member. The offshore wind power foundation according to claim 1 or 2.

8. The offshore wind foundation is a jacket structure, The offshore wind foundation further includes a first brace and a second brace, The first steel pipe and the second steel pipe are at least a part of the first brace, The abutment member is the second brace. The offshore wind power foundation according to claim 1 or 2.

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