Method for removing assembly jig, and assembly jig

Abstract

To provide a method for removing an assembly jig that enables removal of the assembly jig without removing legs and braces from a jacket structure for an offshore wind turbine without interfering the legs and braces, and an assembly jig.SOLUTION: There is provided a method for removing an assembly jig 1, which comprises: a support tower 10 erected in the center of an assembly area BA of a jacket structure J for an offshore wind turbine; support arms 20 extending radially from the top of the support tower 10; and leg supports 30 provided at each end of the support arms 20 and supporting a leg J1 erected in the assembly area BA. The method includes a passing step in which the assembly jig 1 passes through a top end area A1 which is provided along the horizontal direction and surrounded by the top end of each of the legs J1, or a side area A2, which is surrounded by the legs J1 and the bottom surface of the brace J2 and the ground.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a method for removing an assembly jig and an assembly jig.

Background Art

[0002] Conventionally, a jacket structure J for an offshore wind turbine has been built in a yard. Patent Document 1 discloses that at least a part of an assembly jig used for assembling a jacket structure J for an offshore wind turbine is removed by an operator using a crane or the like. Patent Document 1 also discloses releasing the connection between the upper tower part and the middle tower part of the assembly jig, and at this time, releasing the connection between the upper tower part and the support arm and removing the support arm and the upper tower part.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, a jacket structure J for an offshore wind turbine usually has at least three legs and braces that connect adjacent legs among these legs. When removing at least a part of the assembly jig during the construction of the jacket structure J for an offshore wind turbine, interference between these legs and braces becomes a problem. And there is room for improvement in the solution to such a problem in Patent Document 1.

[0005] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a method for removing an assembly jig and an assembly jig that can remove the assembly jig without removing the legs and braces from the jacket structure J for an offshore wind turbine and without interfering with these legs and braces.

Means for Solving the Problems

[0006] <1>The method for removing an assembly jig according to Embodiment 1 of the present disclosure is a method for removing an assembly jig of a jacket structure J for an offshore wind turbine, which has at least three legs and a brace that connects adjacent legs among the at least three legs, and includes a support tower erected at the center of an assembly area of the jacket structure J for an offshore wind turbine, at least three support arms radially extending from the upper part of the support tower, and at least three leg support parts respectively provided at the tips of the at least three support arms and respectively supporting the at least three legs standing in the assembly area. The method is characterized by including a passing step in which the assembly jig passes through an upper end region along the horizontal direction and surrounded by the upper ends of the at least three legs, or a side surface region surrounded by the legs, the lower surface of the brace, and the ground.

Advantages of the Invention

[0007] According to the present disclosure, it is possible to provide a method for removing an assembly jig and an assembly jig that can remove the assembly jig without removing the legs and the brace from the jacket structure J for an offshore wind turbine and without interfering with these legs and the brace.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0009] Hereinafter, with reference to the drawings, an assembly jig according to an embodiment of the present disclosure and a method for removing the assembly jig will be described. The assembly jig according to the present embodiment is used when building a jacket structure for an offshore wind turbine. First, the jacket structure for an offshore wind turbine according to the present embodiment will be described.

[0010] (Regarding the configuration of the jacket structure for an offshore wind turbine) FIG. 1 is a perspective view of a jacket structure J for an offshore wind turbine according to an embodiment. FIG. 2 is a front view showing the state of the jacket structure J for an offshore wind turbine during assembly. FIG. 3 is a first example of a plan view showing the state of the jacket structure J for an offshore wind turbine during assembly. FIG. 4 is a second example of a plan view showing the state of the jacket structure J for an offshore wind turbine during assembly. As shown in FIG. 1, the jacket structure J for an offshore wind turbine includes legs J1, braces J2, and a transition piece J3.

[0011] The leg J1 extends in the vertical direction. The leg J1 may extend parallel to the vertical direction, for example, or may be inclined with respect to the vertical direction. For the leg J1, a steel pipe is used, for example. Also, the leg J1 may have a changing inclination angle during its extension in the vertical direction. The lower end of the leg J1 is connected to a pile (not shown) driven into the seabed ground. The upper end of the leg J1 is connected to the transition piece J3. By this, the leg J1 supports the transition piece J3 on the sea. In the jacket structure J for an offshore windmill, at least three legs J1 are provided. By this, the transition piece J3 is supported by at least three legs J1. Thereby, the leg J1 enables stable support of the transition piece J3. In the present embodiment, four legs J1 are provided as shown in FIG. 1. Note that the present invention is not limited to this, and five or more legs J1 may be provided.

[0012] The brace J2 connects adjacent legs J1 to each other in the circumferential direction with the vertical direction as the axis in the jacket structure J for an offshore windmill. By this, the brace J2 reinforces the jacket structure J for an offshore windmill. For the brace J2, a steel pipe is used, for example. The brace J2 and the leg J1 are joined by welding, for example. The brace J2 is arranged in an X shape, for example, between the legs J1 as shown in FIG. 1. The X shape may be provided in two stages in the vertical direction, for example. The transition piece J3 is connected to the upper parts of a plurality of legs J1 provided in the jacket structure J for an offshore windmill. The lower part of the tower of the offshore windmill WM is connected to the transition piece J3. By this, the transition piece J3 supports the offshore windmill WM. With the above-described respective configurations, the jacket structure J for an offshore windmill is configured.

[0013] (Regarding the upper end region and the side surface region) The jacket structure J for an offshore windmill according to the present embodiment has an upper end region A1 and a side surface region A2 during construction. As shown in FIGS. 2 and 3, the upper end region A1 is a region surrounded by the upper ends of a plurality of legs J1 provided in the jacket structure J for an offshore windmill. The upper end region A1 extends along the horizontal direction. The upper end region A1 is closed by joining a transition piece J3 to the upper ends of the legs J1. As shown in FIG. 2, the side region A2 is a region formed after the connection between the legs J1 by the braces J2 is completed. That is, the side region A2 is a region surrounded by the legs J1, the lower surface of the braces J2, and the ground in the jacket structure J for an offshore windmill under construction arranged in the assembly area BA. The assembly jig 1 according to the present embodiment is removed from the jacket structure J for an offshore windmill by passing through the upper end region A1 or the side region A2 (details will be described later).

[0014] (Configuration of the assembly jig) Next, the configuration of the assembly jig 1 according to the present embodiment will be described. FIG. 5 is a perspective view of the assembly jig 1 according to the embodiment. FIG. 6 is a front view of the assembly jig 1 according to the embodiment. As shown in FIGS. 2, 3, and 4, the assembly jig 1 is used when constructing the jacket structure J for an offshore windmill. The jacket structure J for an offshore windmill is constructed, for example, in the assembly area BA shown in FIG. 2. The assembly area BA is provided, for example, in a yard. In the assembly area BA, for example, a plurality of legs J1 are set upright on the ground by the assembly jig 1. In this state, the braces J2 connecting the legs J1 to each other are joined by welding or the like. As shown in FIG. 5, the assembly jig 1 includes a support tower 10, a support arm 20, and a leg support portion 30.

[0015] The support tower 10 is erected at the center of the assembly area BA. The support tower 10 includes a leg portion 11 and a shaft portion 12. The leg portion 11 is the part of the support tower 10 that contacts the ground in the assembly area BA. The leg portion 11 is formed in a cross shape, for example, as shown in FIG. 5. The leg portion 11 is provided to stably erect the shaft portion 12 in the assembly area BA. In the present embodiment, for example, filled concrete may be filled inside the leg portion 11 formed in a cross shape. By increasing the weight of the leg portion 11 in this way, the shaft portion 12 may be stably erected. The shaft portion 12 extends in the vertical direction. The leg portion 11 is connected to the lower part of the shaft portion 12. The support arm 20 described below is connected to the upper part of the shaft portion 12.

[0016] During the construction of the jacket structure J for an offshore wind turbine, the support arm 20 supports a plurality of legs J1. The work of connecting the legs J1 to each other by braces J2 is performed in a state where the legs J1 are supported by the support arm 20, as shown in FIGS. 2 and 3. The support arm 20 is a rod-shaped member whose one end is connected to the upper part of the shaft portion 12. More specifically, one end of the support arm 20 is connected to a base portion 12a1 provided at the upper part of the shaft portion 12. The support arm 20 extends along the horizontal direction, for example, during the construction of the jacket structure J for an offshore wind turbine, as shown in FIG. 6. One support arm 20 is provided for each of the legs J1 provided in the jacket structure J for an offshore wind turbine. That is, during the construction of the jacket structure J for an offshore wind turbine, the support arm 20 extends radially from the upper part of the support tower 10 in accordance with the number and position of the legs J1.

[0017] As described above, in the jacket structure J for an offshore wind turbine, at least three legs J1 are provided. Therefore, in the assembly jig 1, at least three support arms 20 are provided. In the present embodiment, the assembly jig 1 includes four support arms 20, as shown in FIG. 5. Note that the present invention is not limited to this, and five or more support arms 20 may be provided in accordance with the number of legs J1 of the jacket structure J for an offshore wind turbine.

[0018] The assembly jig 1 according to this embodiment is used for the construction of a plurality of different types of offshore windmill jacket structures J, such as the length of the leg J1, the diameter of the leg J1, the distance between the legs J1, and the relative angle of the legs J1 with respect to the vertical direction. Therefore, the support arm 20 can be extended or contracted in length according to the size or shape of the offshore windmill jacket structure J to be constructed.

[0019] FIG. 7 is an example of the support arm viewed from above. The support arm 20 may have, for example, a length adjustment portion 21 for making the length of the support arm 20 adjustable as shown in FIG. 7. In this case, the support arm 20 has a first arm 20a, a second arm 20b, and a length adjustment portion 21. The first arm 20a is fixed to the upper end portion of the support tower 10. The second arm 20b is connected to the first arm 20a via the length adjustment portion 21, and one end thereof is fixed to the leg support portion 30.

[0020] The length adjustment portion 21 is a member that makes the length of the support arm 20 adjustable. The length adjustment portion 21 includes, for example, an arm intermediate portion 21a, a first connecting portion 21b, and a second connecting portion 21c. The arm intermediate portion 21a is interposed between the first arm 20a and the second arm 20b. The first connecting portion 21b detachably connects between the first arm 20a and the arm intermediate portion 21a. The second connecting portion 21c detachably connects between the arm intermediate portion 21a and the second arm 20b. Since the first connecting portion 21b and the second connecting portion 21c are detachable, by preparing in advance two or more types of arm intermediate portions 21a having different lengths, the arm intermediate portion 21a can be replaced. Thereby, the length of the support arm 20 is adjusted. Note that the length adjustment portion 21 may include an arm intermediate portion 21a whose length is extendable and contractible, and the length of the support arm 20 may be adjusted by the extension and contraction of the arm intermediate portion 21a itself.

[0021] As shown in FIGS. 3 and 5, the leg support part 30 is provided at the tip of each of a plurality of support arms 20 provided in the assembly jig 1. The leg support part 30 is provided at the opposite end of the other end of the support arm 20, that is, the end attached to the base part 12a1 of the shaft part 12 of the support tower 10. The leg support part 30 supports each of a plurality of legs J1 in a state where they are set up in the assembly area BA. The leg support part 30 includes, for example, an opening 31 for facilitating the support of the leg J1. When the leg J1 is supported by the leg support part 30, the leg J1 is disposed in this opening 31. In order to form the opening 31, the leg support part 30 is preferably formed in a U shape or a V shape, for example. Alternatively, the leg support part 30 may have any other shape as long as it is a shape that facilitates the support of the leg J1. With the above-described respective configurations, the assembly jig 1 is configured.

[0022] (Regarding the deformation of the assembly jig) In the present embodiment, the assembly jig 1 is deformable. Here, the assembly jig 1 that supports the leg J1 during the construction of the jacket structure J for an offshore wind turbine is removed from the jacket structure J for an offshore wind turbine after the construction of the jacket structure J for an offshore wind turbine is completed. At this time, if the assembly jig 1 remains in the shape when it supported the leg J1, when removing the assembly jig 1, it interferes with the leg J1 or the brace J2 of the jacket structure J for an offshore wind turbine. Therefore, by making the assembly jig 1 deformable, it is possible to prevent interference with the leg J1 or the brace J2 when removing the assembly jig 1 from the jacket structure J for an offshore wind turbine.

[0023] In the present embodiment, after being deformed, the assembly jig 1 is removed from the jacket structure J for an offshore wind turbine so as to pass through the upper end region A1 or the side surface region A2 in the jacket structure J for an offshore wind turbine under construction. That is, in the present embodiment, the assembly jig 1 is deformable to a size that can pass through the upper end region A1 or the side surface region A2 formed in the jacket structure J for an offshore wind turbine under construction. Note that, as described above, the upper end region A1 is closed by joining the transition piece J3 to the upper end of the leg J1. Therefore, it is preferable that the assembly jig 1 is removed, for example, after the joining of the leg J1 and the brace J2 is completed and before joining the transition piece J3 to at least the upper end of the leg J1.

[0024] Hereinafter, four examples of the deformation of the assembly jig 1 will be described. FIG. 8 is a front view showing a state in the middle of bending the support arm 20 of the assembly jig 1. FIG. 9 is a front view showing a state where the support arm 20 of the assembly jig 1 is bent. FIG. 10 is a front view showing a state where the assembly jig 1 is divided vertically. FIG. 11 is a front view showing the lifting step S4. FIG. 12 is a front view showing the moving step S5.

[0025] A first example of the deformation of the assembly jig 1 will be described. That is, the assembly jig 1 can be deformed to a size that allows it to pass through the upper end region A1 or the side surface region A2, for example, by bending the support arm 20 as shown in FIGS. 6, 8, and 9. In order to enable the bending of the support arm 20, in the present embodiment, the support arm 20 is, for example, pin-joined to the base portion 12a1 of the shaft portion 12 of the support tower 10 as shown in FIG. 6. Thus, the support arm 20 can rotate about the pin P at the connection portion with the shaft portion 12 as shown in FIGS. 6, 8, and 9. Thereby, the support arm 20 connected to the shaft portion 12 of the support tower 10 can be bent at the connection portion between the support arm 20 and the shaft portion 12 as shown in FIG. 10 from the state of extending in the horizontal direction as shown in FIG. 6.

[0026] In this embodiment, the support arm 20 is fixed by the attachment plate SP so as to maintain a horizontally extended state. That is, one end of the support arm 20 and the base portion 12a1 of the shaft portion 12 are connected by the attachment plate SP as shown in FIG. 6. The attachment plate SP is a plate-shaped member having bolt holes. The attachment plate SP is fixed to one end of the support arm 20 and the base portion 12a1 of the shaft portion 12 by bolts (not shown), respectively. This keeps the support arm 20 horizontal.

[0027] When bending the support arm 20, remove the attachment plate SP. By doing this, the other end of the support arm 20 moves downward, and the bending of the support arm 20 is completed. When bending the support arm 20, in order to suppress the sudden drop of the other end of the support arm 20, as shown in FIG. 8, while supporting the other end of the support arm 20 by a hoisting cable R by a crane (not shown), it is preferable to move the other end of the support arm 20 downward.

[0028] In order to stabilize the position of the support arm 20 after being bent, it is preferable that contact portions 12a2 are formed in the vicinity of the connection portion between the base portion 12a1 of the shaft portion 12 and the support arm 20, as shown in FIG. 6, for example. The contact portions 12a2 provided on the base portion 12a1 of the shaft portion 12 and the support arm 20 respectively contact each other after the support arm 20 is bent, as shown in FIG. 9. By this, it is possible to suppress the unintentional swinging of the support arm 20 after being bent and stabilize the support arm 20. After the support arm 20 is bent, the contact portions 12a2 provided on the base portion 12a1 of the shaft portion 12 and the support arm 20 respectively may be fixed to each other by, for example, bolt fastening.

[0029] By bending the support arm 20 in this way, among the assembly jigs 1, the upper shaft portion 12a, which will be described later, deforms to a size such that it is included in the upper end region A1 when viewed along the vertical direction as shown in FIG. 4. That is, the upper shaft portion 12a deforms to a size that can pass through the upper end region A1 as shown in FIG. 11 by being lifted by a crane or the like (not shown).

[0030] A second example of the deformation of the assembly jig 1 will be described. That is, the assembly jig 1 may be deformable to a size that can pass through the upper end region A1 or the side surface region A2, for example, by contracting the length L1 of the support arm 20 shown in FIG. 9. The contraction of the support arm 20 can utilize the above-described functions provided by the support arm 20. That is, as described above, the support arm 20 can be extended or contracted in length L1 by the length adjustment portion 21 shown in FIG. 7 according to the size or shape of the jacket structure J for an offshore windmill to be constructed. By using this function to contract the support arm 20, the upper shaft portion 12a may be deformed to a size that can pass through the upper end region A1. When deforming the upper shaft portion 12a to a size that can pass through the upper end region A1, only the support arm 20 may be bent, or both the bending of the support arm 20 and the contraction of the support arm 20 may be performed. Alternatively, if the upper shaft portion 12a can be deformed to a size that can pass through the upper end region A1 only by the contraction of the support arm 20, only the contraction of the support arm 20 may be performed.

[0031] A third example of the deformation of the assembly jig 1 will be described. That is, the assembly jig 1 may be deformable to a size that can pass through the upper end region A1 or the side surface region A2, for example, by removing a part of the tip side of the support arm 20 from the support arm 20. That is, the assembly jig 1 may be able to remove the leg support portion 30 from the support arm 20. In order to enable the removal of the leg support portion 30 from the support arm 20, for example, the leg support portion 30 and the support arm 20 are preferably joined by bolts (not shown). Thus, by removing the leg support portion 30 from the support arm 20, the upper shaft portion 12a may be deformed to a size that allows it to pass through the upper end region A1.

[0032] A fourth example of the deformation of the assembly jig 1 will be described. That is, the assembly jig 1 may be deformable to a size that allows it to pass through the upper end region A1 or the side surface region A2, for example, by being divided in the vertical direction as shown in FIG. 10. More specifically, the shaft portion 12 of the support tower 10 in the assembly jig 1 is dividable in the vertical direction. That is, the shaft portion 12 is dividable into a lower shaft portion 12b including a connection portion with the leg portion 11 and an upper shaft portion 12a including a connection portion with the support arm 20. This enables the assembly jig 1 to be dividable in the vertical direction. In the present embodiment, for example, the inside of the lower shaft portion 12b may be filled with packed concrete. By lowering the center of gravity of the shaft portion 12 in this way, the shaft portion 12 may be stably erected.

[0033] The lower shaft portion 12b and the upper shaft portion 12a are connected by the structure described below. That is, as shown in FIG. 6, a ring plate R1 and a rib plate R2 are provided at the upper end of the lower shaft portion 12b and the lower end of the upper shaft portion 12a, respectively. The lower shaft portion 12b and the upper shaft portion 12a are joined by joining the rib plates R2 provided on the lower shaft portion 12b and the upper shaft portion 12a with an attachment plate R3. The ring plate R1 is an annular member provided over the circumferential direction of the upper end of the lower shaft portion 12b and the lower end of the upper shaft portion 12a. The ring plate R1 is provided to reinforce the connection between the rib plate R2 described below and the upper end of the lower shaft portion 12b and the lower end of the upper shaft portion 12a. The rib plate R2 is a plate-like member provided along the vertical direction. A plurality of rib plates R2 are provided at intervals along the circumferential direction of the upper end of the lower shaft portion 12b and the lower end of the upper shaft portion 12a. In the present embodiment, the upper end of the lower shaft portion 12b, the lower end of the upper shaft portion 12a, the ring plate R1, and the rib plate R2 are fixed to each other by welding, for example. In the present embodiment, the lower shaft portion 12b and the upper shaft portion 12a are connected as follows. That is, first, the rib plates R2 provided at the upper end of the lower shaft portion 12b and the upper shaft portion 12a, respectively, are arranged so as to abut against each other. In that state, a pair of attaching plates R3 are arranged so as to sandwich the rib plates R2 abutting against each other. Then, the pair of attaching plates R3, the rib plate R2 of the lower shaft portion 12b, and the rib plate R2 of the upper shaft portion 12a are fixed by bolts B and nuts N. By this, the lower shaft portion 12b and the upper shaft portion 12a are connected. At this time, high-strength bolts are preferably used for the bolts B. The division of the lower shaft portion 12b and the upper shaft portion 12a is preferably performed, for example, by lifting the upper shaft portion 12a with a crane (not shown) after removing the bolts B, nuts N for fastening the rib plates R2 to each other and the attaching plates R3 as described above.

[0034] By dividing the assembling jig 1 in this way, among the assembling jig 1, the lower shaft portion 12b is deformed to such a size as to be included in the side surface region A2 when viewed along the horizontal direction as shown in FIG. 12. That is, the lower shaft portion 12b is deformed to such a size that the jacket structure J for an offshore windmill and the lower shaft portion 12b can pass through the side surface region A2 by moving relative to each other in the horizontal direction.

[0035] (Method for removing the assembling jig) Next, a method for removing the assembling jig 1 in the construction process of the jacket structure J for an offshore windmill according to the present embodiment will be described. FIG. 13 is a flow of the method for removing the assembling jig 1 according to the embodiment. The removing method according to the present embodiment includes a passing step S. In the passing step S, the assembling jig 1 deformed along the above-described form is passed through the upper end region A1 or the side surface region A2 of the jacket structure J for an offshore windmill under construction. In the present embodiment, the passing step S includes a deforming step S1, an inserting step S2, an attaching step S3, a lifting step S4, and a moving step S5.

[0036] The deformation step S1 is a step of deforming the assembly jig 1. That is, in the deformation step S1, the assembly jig 1 is deformed along the forms according to the above four examples. Thus, in the lifting step S4 or the moving step S5, the assembly jig 1 is deformed to a size that can pass through the upper end region A1 or the side surface region A2 in the jacket structure J for an offshore windmill under construction.

[0037] In the deformation step S1, for example, as shown in FIG. 4, the assembly jig 1 is deformed so that, when viewed along the vertical direction, it is included in the upper end region A1. Alternatively, in the deformation step S1, as shown in FIG. 12, the assembly jig 1 is deformed so that, when viewed along the horizontal direction, it is included in the side surface region A2. The deformation step S1 includes, for example, a bending step S1A, a shrinking step S1B, a removing step S1C, and a dividing step S1D.

[0038] The bending step S1A is a step of bending the support arm 20 along the first example of the deformation of the assembly jig 1 described above. Thus, at least the upper shaft portion 12a can pass through the upper end region A1. The shrinking step S1B is a step of shrinking the support arm 20 along the second example of the deformation of the assembly jig 1 described above. Thus, the upper shaft portion 12a can more surely pass through the upper end region A1. Note that the shrinking step S1B may not be performed when the upper shaft portion 12a can surely pass through the upper end region A1. The removing step S1C is a step of removing a part on the tip side of the support arm 20 from the support arm 20 along the third example of the deformation of the assembly jig 1 described above. That is, the removing step S1C is a step of removing the leg support portion 30 from the support arm 20. Note that the removing step S1C may not be performed when the upper shaft portion 12a can surely pass through the upper end region A1. The splitting step S1D is a step of splitting the shaft portion 12 of the support tower 10 into an upper shaft portion 12a and a lower shaft portion 12b along the fourth example of the deformation of the above-described assembly jig 1. That is, in the splitting step S1D, it is a process of removing the bolts B and nuts N connecting the upper shaft portion 12a and the lower shaft portion 12b from the rib plate R2. By this, in the lifting step S4 described later, only the upper shaft portion 12a can be lifted by a crane (not shown).

[0039] The insertion step S2 is a process of inserting the lifting cable R into the upper end region A1 after the deformation step S1 and before the attachment step S3. The lifting cable R is a rope connecting a crane (not shown) and the upper shaft portion 12a. By inserting the lifting cable R into the upper end region A1 in the insertion step S2, the lifting cable R can be connected to the upper shaft portion 12a.

[0040] The attachment step S3 is a process of attaching the lifting cable R to the assembly jig 1 at least after the deformation step S1, as shown in FIG. 9. In the present embodiment, the attachment step S3 is performed after the insertion step S2. That is, the attachment step S3 is a process of connecting the lifting cable R inserted through the upper end region A1 in the insertion step S2 to the upper shaft portion 12a. By connecting the lifting cable R to the upper shaft portion 12a in the attachment step S3, as shown in FIG. 10, the upper shaft portion 12a can be lifted by a crane (not shown). As shown in FIG. 9, the lifting cable R is attached to the hanging piece HP. The hanging piece HP is formed at four locations, for example, on the upper surface of the base portion 12a1 provided at the upper end of the shaft portion 12. It is preferable to attach the lifting cable R one by one to the four formed hanging pieces HP to stabilize the posture of the upper shaft portion 12a during lifting.

[0041] The lifting step S4 is a step of lifting the upper shaft portion 12a upward as shown in FIG. 11 using a lifting cable R connected to the upper shaft portion 12a. That is, in the lifting step S4, the upper shaft portion 12a is moved upward by pulling the lifting cable R upward by a crane (not shown). By doing this, the upper shaft portion 12a is removed from the offshore windmill jacket structure J by passing through the upper end region A1.

[0042] The moving step S5 is a step of relatively moving the lower shaft portion 12b and the offshore windmill jacket structure J in the horizontal direction as shown in FIG. 12. By doing this, the lower shaft portion 12b is passed through so as to pass through the side region A2. By doing this, the lower shaft portion 12b is removed from the offshore windmill jacket structure J. In the moving step S5, for example, the offshore windmill jacket structure J may be supported by a dolly (not shown) and the offshore windmill jacket structure J may be moved by the dolly. Alternatively, in the moving step S5, the assembly jig 1 may be supported by a dolly (not shown) and the assembly jig 1 may be moved by the dolly. By the above steps, the removal of the assembly jig 1 according to the present embodiment is performed.

[0043] As described above, according to the method for removing the assembly jig 1 according to the present embodiment, a passing step S for removing the assembly jig 1 used in the assembly of the jacket structure J for an offshore wind turbine is provided. In the passing step S, the assembly jig 1 passes through an upper end region A1 surrounded by the upper ends of at least three legs J1, or a side surface region A2 surrounded by the legs J1, the lower surface of the brace J2, and the ground. That is, the assembly jig 1 is removed from the jacket structure J for an offshore wind turbine by passing the assembly jig 1 through between the legs J1 while avoiding the brace J2. Thereby, for example, when removing the assembly jig 1 from the jacket structure J for an offshore wind turbine, it is possible to suppress the interference of the assembly jig 1 with the legs J1 and the brace J2 connecting the legs J1 to each other. Therefore, when removing the assembly jig 1, it is possible to eliminate the need to remove the legs J1 and the brace J2 from the jacket structure J for an offshore wind turbine.

[0044] Further, the passing step S includes a deformation step S1 of deforming the assembly jig 1. In the deformation step S1, the assembly jig 1 is deformed so as to be included in the upper end region A1 when viewed along the vertical direction, or the assembly jig 1 is deformed so as to be included in the side surface region A2 when viewed along the horizontal direction. Thereby, when removing the assembly jig 1 from the jacket structure J for an offshore wind turbine, it is possible to more reliably suppress the interference of the assembly jig 1 with the legs J1 and the brace J2 connecting the legs J1 to each other.

[0045] Further, in the deformation step S1, for example, the assembly jig 1 is deformed so that the assembly jig 1 is included in the upper end region A1 when viewed along the vertical direction. Then, the passing step S further includes an attachment step S3 of attaching a lifting cable R to the assembly jig 1 after the deformation step S1. Here, for example, if a lifting cable R for lifting the assembly jig 1 is attached before deforming the assembly jig 1, the crane for lifting the assembly jig 1 will be restricted during the deformation step S1, which is the operation of deforming the assembly jig 1. As described above, by performing the attachment step S3 after the deformation step S1, the time for restraining the crane can be shortened.

[0046] Further, the passing step S further includes an insertion step S2 of inserting the lifting cable R into the upper end region A1 after the deformation step S1 and before the attachment step S3. That is, in the insertion step S2, the lifting cable R passes from above the jacket structure J for an offshore wind turbine through the upper end region A1 surrounded by the upper ends of at least three legs J1 provided in the jacket structure J for an offshore wind turbine, and is attached to the assembly jig 1. Thus, by performing the attachment step S3 after the deformation step S1, the time for restraining the crane can be shortened, and in the insertion step S2, the deformed assembly jig 1 can be more reliably passed through the upper end region A1 by the lifting cable R passing through the upper end region A1 and being attached to the assembly jig 1.

[0047] Further, the deformation step S1 further includes, for example, a bending step S1A of bending the support arm 20. In this way, by deforming the assembly jig 1 only by bending the support arm 20, the deformation of the assembly jig 1 can be made an easy operation and the working time can be shortened. Therefore, the deformation step S1 can be performed efficiently.

[0048] Further, the deformation step S1 may further include a contraction step S1B of contracting the support arm 20. Here, the support arm 20 of the assembly jig 1 can be extended or contracted in length according to the size or shape of the jacket structure J for an offshore wind turbine to be constructed. Therefore, the contraction step S1B can be implemented by utilizing the existing function of the support arm 20. By enabling some steps of the deformation step S1 to be performed by utilizing the existing function in this way, it is possible to contribute to the efficient removal of the assembly jig 1 without adding special functions or the like to the assembly jig 1.

[0049] Further, the deformation step S1 may further include a removal step S1C of removing a part of the tip side of the support arm 20 from the support arm 20. Thereby, the size when removing the assembly jig 1 from the jacket structure J for an offshore wind turbine can be made smaller. Therefore, for example, even when the upper end region A1 or the side surface region A2 of the jacket structure J for an offshore wind turbine is small, the assembly jig 1 can be easily removed.

[0050] Moreover, according to the assembly jig 1 according to the present embodiment, it can be deformed to a size that can pass through the upper end region A1 along the horizontal direction of the jacket structure J for an offshore wind turbine, which is the upper end region A1 surrounded by the upper ends of at least three legs J1, or the side surface region A2 surrounded by between the legs J1, the lower surface of the brace J2, and the ground. Thereby, for example, when removing the assembly jig 1 from the jacket structure J for an offshore wind turbine, it is possible to suppress the assembly jig 1 from interfering with the legs J1 and the brace J2 that connects the legs J1 to each other. Therefore, when removing the assembly jig 1, it is possible to eliminate the need to remove the legs J1 and the brace J2 from the jacket structure J for an offshore wind turbine.

[0051] In addition, the assembly jig 1 can be deformed to a size that can pass through the upper end region A1 or the side surface region A2 by bending the support arm 20. In this way, by deforming the assembly jig 1 only by bending the support arm 20, the deformation of the assembly jig 1 can be made an easy operation and the working time can be shortened. Therefore, the deformation of the assembly jig 1 can be performed efficiently.

[0052] Note that the technical scope of the present disclosure is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present disclosure. For example, when removing the assembly jig 1, the support arm 20 may be removed from the shaft portion 12 of the support tower 10, and the support arm 20 may be individually removed by a crane. Further, the upper part 12a of the shaft may be removed by moving it horizontally using a suspension scale or the like through the gap of the X-shaped brace J2 provided, for example, in two upper and lower stages. Also, as described with reference to FIG. 8, when bending the support arm 20, it is preferable to support the support arm 20 with a crane. Alternatively, a hydraulic cylinder capable of decelerating the rotational movement of the support arm 20 may be provided.

[0053] In addition, within the scope not departing from the gist of the present disclosure, it is possible to appropriately replace the components in the above-described embodiment with well-known components, and the above-described modified examples may be appropriately combined.

Explanation of Reference Numerals

[0054] 1 Assembly jig 10 Support tower 11 Legs 12 Shaft portion 12a Upper part of the shaft 12a1 Base portion 12a2 Contact portion 12b Lower part of the shaft 20 Support arm 20a First arm 20b Second arm 21 Adjusting portion 21a Middle portion of the arm 21b First connecting portion 21c Second connecting portion 30 Leg support portion 31 Opening A1 Upper end region A2 Side region B Bolt BA Assembly area HP Suspension piece J Jacket structure for offshore wind turbine J1 Leg J2 Brace J3 Transition piece N Nut P Pin R Lifting rope R1 Ring plate R2 Rib Plate R3 Attachment Plate S Passing Step S1 Deformation Step S1A Step S1B Shrinkage Step S1C Step S1D Division Step S2 Insertion Step S3 Step S4 Step S5 Movement Step SP Attachment Plate WM Offshore Wind Turbine

Claims

1. A support tower erected at the center of an assembly area of a jacket structure for an offshore wind turbine, the jacket structure having at least three legs and braces connecting adjacent legs among the at least three legs, at least three support arms extending radially from the upper part of the support tower, and at least three leg support parts respectively provided at the tips of the at least three support arms and supporting the at least three legs in a state where they are erected in the assembly area. A method for removing an assembly jig for a jacket structure of an offshore wind turbine, comprising: a passing step in which the assembly jig passes through an upper end region along the horizontal direction and surrounded by the upper ends of the at least three legs, or a side region surrounded by the legs, the lower surface of the brace, and the ground, characterized in that it comprises the above.

2. The passing step is a deforming step of deforming the assembly jig so that the assembly jig is included in the upper end region when viewed along the vertical direction, or a deforming step of deforming the assembly jig so that the assembly jig is included in the side region when viewed along the horizontal direction, further comprising a deforming step of deforming the assembly jig, The method for removing an assembly jig according to claim 1, characterized in that it further comprises the above.

3. In the deforming step, the assembly jig is deformed so that the assembly jig is included in the upper end region when viewed along the vertical direction, The passing step is a mounting step of attaching a lifting cable to the assembly jig after the deforming step, The method for removing an assembly jig according to claim 2, characterized in that it further comprises the above.

4. The passing step is an inserting step of inserting the lifting cable into the upper end region after the deforming step and before the mounting step, The method for removing an assembly jig according to claim 3, characterized in that it further comprises the above.

5. The deforming step is a bending step of bending the support arm, The method for removing an assembly jig according to any one of claims 2 to 4, characterized in that it further comprises the above.

6. The deforming step is a contracting step of contracting the support arm, The method for removing an assembly jig according to any one of claims 2 to 4, characterized in that it further comprises the above.

7. The deforming step is a removing step of removing a part of the tip side of the support arm from the support arm, The method for removing the assembly jig according to any one of claims 2 to 4, further comprising

8. A support tower erected at the center of an assembly area of an offshore windmill jacket structure having at least three legs and braces connecting adjacent legs among the at least three legs, At least three support arms extending radially from the upper part of the support tower, An assembly jig for an offshore windmill jacket structure, comprising at least three leg support parts respectively provided at the tips of the at least three support arms and respectively supporting the at least three legs standing in the assembly area, The assembly jig is deformable to a size that can pass through an upper end region along the horizontal direction and surrounded by the upper ends of each of the at least three legs, or a side surface region surrounded by the legs, the lower surface of the brace, and the ground. An assembly jig characterized by this.

9. The assembly jig is deformable to a size that can pass through the upper end region or the side surface region by bending the support arm. The assembly jig according to claim 8, characterized by this.

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