Construction method of windmill foundation without transition piece

Abstract

To reduce steps required to assemble a windmill to improve construction efficiency.SOLUTION: A construction method of a windmill foundation without a transition piece includes the steps of: attaching a flange protective plate to a flat upper end joint surface 21a radially inward from an outer circumferential surface of a monopile 2; striking the flange protective plate from above with a driving part of a monopile driving machine to drive the monopile 2 into the seabed ground; removing the flange protective plate from the upper end joint surface 21a; and bringing a lower end joint surface 31a of a windmill tower 3 into liquid-tight surface contact from above with the upper end joint surface 21a, to achieve bolt connection inside the monopile 2 and the windmill tower 3.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a construction method for a wind turbine foundation without a transition piece. [Background technology]

[0002] Conventionally, a wind turbine as an offshore structure has been known that has a monopile driven into the seabed, a transition piece for adjusting the inclination of the monopile, and a wind turbine tower made of a steel pipe installed on the transition piece (see, for example, Patent Document 1).

[0003] In such conventional wind turbines, the monopile is driven into the seabed by striking its upper end with a monopile driving machine. After the monopile is driven into the seabed, the upper surface of the transition piece is adjusted so as to be horizontal, and high-strength grout is filled between the monopile and the transition piece to fix them in place. The wind turbine tower is then placed on the upper end of the transition piece and bolted to it. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-35768 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional wind turbines are structured so that a transition piece is provided between the monopile and the wind turbine tower, which reduces construction efficiency and leaves room for improvement in this regard.

[0006] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a construction method for a wind turbine foundation without a transition piece, which can reduce the number of steps required for assembling a wind turbine and improve construction efficiency. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the construction method of the present invention for a wind turbine foundation without a transition piece is a construction method for a wind turbine foundation without a transition piece that connects a monopile driven into the ground and a wind turbine tower made of a steel pipe installed on the monopile, and is characterized by comprising the steps of: attaching a joint surface protection member to the flat upper end joint surface formed at the upper end of the monopile; striking the joint surface protection member from above with a driving part of a monopile driving machine to drive the monopile into the ground; removing the joint surface protection member from the upper end joint surface; and bolting the lower end joint surface of the wind turbine tower to the upper end joint surface in liquid-tight surface contact from above.

[0008] In the construction method of a wind turbine foundation without a transition piece according to the present invention, the wind turbine tower can be directly joined to the monopile driven into the ground. When driving the monopile, the monopile is driven by the driving part of the monopile driving machine with the joint surface protection member attached to the upper joint surface of the monopile for protection. Therefore, the upper joint surface of the monopile during driving can be protected by the joint surface protection member, and the upper joint surface is not damaged by the large repeated stress due to the impact energy of the striking monopile driving machine, for example, when striking the monopile with the driving part of the monopile driving machine. As a result, when joining the wind turbine tower, the joint surface protection member can be removed from the upper joint surface, and the lower joint surface of the wind turbine tower can be brought into liquid-tight surface contact with the upper joint surface of the monopile. In this way, in the present invention, the wind turbine tower and the monopile can be directly joined with bolts, so that the transition piece that was previously used to join the monopile and the wind turbine tower can be omitted, the number of steps required for construction can be reduced, and construction efficiency can be improved.

[0009] Furthermore, in the construction method of the present invention for a wind turbine foundation without a transition piece, a first flange is provided around the entire circumference of the upper end of the monopile, protruding radially inward or outward, the upper end joint surface is the upper surface of the first flange, a second flange is provided that overlaps the upper surface of the first flange and protrudes radially inward or outward around the entire circumference of the lower end of the wind turbine tower, the lower end joint surface is the lower surface of the second flange, and the joint surface protection member is preferably a flange protection plate having a constant thickness covering the upper end joint surface.

[0010] In this case, by providing a first flange on the monopile and a second flange on the wind turbine tower, it becomes easier to ensure a flat joint surface for each flange. Also, the flange protective plate can uniformly cover the entire upper end joint surface of the first flange, which extends all around. Therefore, the striking force of the monopile driver can be applied to the monopile all around in a balanced and uniform manner, which prevents an unbalanced load from acting on the upper end joint surface of the monopile and prevents deformation or damage to the upper end joint surface of the monopile.

[0011] In addition, in the construction method for a wind turbine foundation without a transition piece according to the present invention, it is preferable that the outer periphery of the flange protective plate has an outer periphery convex portion that is convex upwards, and that the outer periphery convex portion is struck by the driving part.

[0012] In this case, the driving part can be brought into contact with only the outer peripheral convex part of the flange protective plate that protects the upper joint surface of the monopile, so that the effect of the impact force that the upper joint surface receives from the driving part can be reduced, and deformation or damage to the upper joint surface of the monopile can be more effectively prevented.

[0013] Furthermore, in the construction method for a wind turbine foundation without a transition piece according to the present invention, it is preferable that the flange protection plate is joined to the first flange by fixing bolts, and that the fixing bolts are fixed in a state where they do not protrude above the upper plate surface of the flange protection plate.

[0014] In this case, by fastening the flange protection plate to the first flange of the monopile with the fixing bolts, the flange protection plate can be easily attached and detached from above the first flange. In this case, the flange protection plate is securely fixed to the monopile, so that the flange protection plate can be prevented from shifting or coming off from the first flange even when the monopile is driven in by the driving section. Furthermore, because the fixing bolts do not protrude above the upper plate surface of the flange protection plate, the driving section can be prevented from interfering with the fixing bolts.

[0015] Furthermore, in the construction method for a wind turbine foundation without a transition piece according to the present invention, it is preferable that a recess is formed in the upper plate surface of the flange protective plate, and a hanging device for hanging a suspension wire is provided inside the recess in a state where it does not protrude above the upper plate surface of the flange protective plate.

[0016] In this case, the flange protection plate can be suspended by hooking a suspending wire to the suspending tool. Since the suspending tool does not protrude above the upper plate surface of the flange protection plate, the driving-in portion can be prevented from interfering with the suspending tool.

[0017] In the construction method for a wind turbine foundation without a transition piece according to the present invention, it is preferable that a suspender for hanging a suspending wire is provided on an inner circumferential surface of the flange protective plate.

[0018] In this case, the flange protection plate can be suspended by hooking a hoisting wire to the hoisting tool. Since the hoisting tool is attached laterally to the inner peripheral surface of the flange protection plate and does not protrude above the upper surface of the flange protection plate, it is possible to prevent the driving part of the monopile driving machine from interfering with the hoisting tool.

[0019] In addition, in the construction method for a wind turbine foundation without a transition piece according to the present invention, it is preferable that a work scaffold is provided around the periphery of the monopile.

[0020] With this configuration, a work scaffold is placed at the joint between the monopile and the wind turbine tower, so that the bolt connection between the monopile and the wind turbine tower can be easily performed using the work scaffold. Effect of the Invention

[0021] According to the construction method of the present invention for a wind turbine foundation without a transition piece, the number of steps required for assembling the wind turbine can be reduced, and construction efficiency can be improved. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a side view showing an overall structure of a wind turbine according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a vertical cross-sectional view showing a bolted joint between a monopile and a wind turbine tower. [Diagram 3] FIG. 13 is a side view of the external platform at the junction of the monopile and the wind turbine tower. [Figure 4] FIG. 2 is a side view showing the driving state of the monopile. [Diagram 5] A cross-sectional view showing the state in which a flange protection plate is fixed to the first flange when driving the monopile. [Figure 6] FIG. 4 is a plan view of a state in which a flange protection plate is fixed to a first flange. [Figure 7] 4 is a cross-sectional view showing the configuration of a first hanger provided on a flange protection plate. FIG. [Figure 8] 10 is a cross-sectional view showing the configuration of a second hanger provided on the flange protection plate. FIG. [Figure 9] FIG. 1 shows the construction state of a wind turbine, where (a) shows the state after the monopile has been driven into place, and (b) shows the state after the wind turbine tower has been joined to the monopile. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, a construction method for a wind turbine foundation without a transition piece according to an embodiment of the present invention will be described with reference to the drawings.

[0024] As shown in Figures 1 to 3, the construction method for wind turbine 1 of this embodiment is a construction method for joining a monopile 2 driven into seabed ground G to a wind turbine tower 3 made of a steel pipe installed on the monopile 2. Note that wind turbine 1 of this embodiment is not limited to being installed on the sea, but may be installed on a lake or on land.

[0025] Here, in the wind turbine 1, the monopile 2 and the wind turbine tower 3 are arranged coaxially, with their common central axis O facing vertically. The direction parallel to this central axis O is defined as the axial direction, the direction revolving around the central axis O is defined as the circumferential direction, and the direction perpendicular to the central axis O is defined as the radial direction. Additionally, the radial direction toward the central axis O is defined as the inward direction, and the direction away from the central axis O is defined as the outward direction.

[0026] The monopile 2 has a circular cross section with, for example, an outer diameter of 5500 mm, a plate thickness of 46 to 85 mm, and a length of 51600 mm. The monopile 2 is driven into the seabed G by striking, pressing, rotary pressing, vibration, or the like. In this embodiment, the monopile is driven into the seabed G by striking using a monopile driving machine 62 (see FIG. 4).

[0027] As shown in Fig. 2, the monopile 2 is provided with a first flange 21 that protrudes radially inward around the entire circumference of its upper end. The upper surface of the first flange 21 has a flat upper end joint surface 21a. The upper end joint surface 21a coincides with the upper end 2a of the monopile 2. The first flange 21 is formed with a plurality of first bolt holes 21b that penetrate in the thickness direction, are arranged at predetermined intervals in the circumferential direction, and through which bolts 32 are inserted. A lower end joint surface 31a of a second flange 31 of the wind turbine tower 3 (described later) abuts against the upper end joint surface 21a from above in liquid-tight surface contact.

[0028] The wind turbine tower 3 has a circular cross section, but may have other cross-sectional shapes, for example a polygonal cross section. The wind turbine tower 3 is coaxial with the monopile 2 and is directly connected to the upper end 2a of the monopile 2 by means of a bolted connection using bolts 32.

[0029] The wind turbine tower 3 is provided with a second flange 31 that protrudes radially inward over the entire circumference of its lower end. The lower surface of the second flange 31 has a flat lower end joint surface 31a. The lower end joint surface 31a coincides with the lower end 3a of the wind turbine tower 3. The second flange 31 is formed with a plurality of second bolt holes 31b that penetrate in the thickness direction, are arranged at predetermined intervals in the circumferential direction, and through which bolts 32 are inserted. The lower end joint surface 31a abuts against the upper end joint surface 21a of the first flange 21 of the monopile 2 from above in liquid-tight surface contact. In other words, the upper end joint surface 21a of the monopile 2 and the lower end joint surface 31a of the wind turbine tower 3 are joined by bolting in liquid-tight surface contact.

[0030] An opening and closing gate (not shown) is provided on the lower side of the wind turbine tower 3. The opening and closing gate allows workers and luggage to enter the inside of the wind turbine tower 3. The joint between the monopile 2 and the wind turbine tower 3 is located inside the wind turbine tower 3, and is joined with bolts inside the tower.

[0031] As shown in Figure 3, an external platform 4 (work scaffolding) is provided on the upper outer periphery of the monopile 2, for example, to provide access to the inside of the wind turbine tower 3 and the monopile 2 and to perform tasks such as wind turbine operation and maintenance, and an internal platform (work scaffolding) (not shown) for performing bolt joining work. The external platform 4 is, for example, a metal frame member, which is attached to the monopile 2 and is fixed to surround the upper part of the monopile 2 from the outside. The external platform 4 is suitable for docking a ship to move workers and goods between the wind turbine 1, and is provided to allow workers to move safely around the monopile 2 and the wind turbine tower 3. The external platform 4 is attached before the wind turbine tower 3 is fixed to the monopile 2. When joining the wind turbine tower 3 to the monopile 2, workers can enter the external platform 4 and the internal platform and efficiently perform positioning and fixing work.

[0032] The external platform 4 includes an intermediate platform 41, an elevator 42, an auxiliary equipment gauge 43, etc. The external platform 4 has a ring-shaped walking section equipped with handrails 44.

[0033] Next, a method for constructing the wind turbine 1 described above will be specifically described with reference to the drawings. First, as shown in Fig. 4, the monopile 2 is driven into the seabed G. At this time, as shown in Figs. 5 and 6, a flange protection plate 5 (joint surface protection member) is attached to the flat upper end joint surface 21a of the first flange 21 of the monopile 2. Then, the monopile 2 is supported on a pile guiding frame 61 provided on a self-elevating work platform 6 shown in Fig. 4. The driving position of the monopile 2 is determined by appropriately moving the pile guiding frame 61. The flange protection plate 5 is usually installed on land, and installation offshore is not necessary.

[0034] Here, as shown in FIG. 5 and FIG. 6, the flange protection plate 5 is a plate-shaped steel member having a certain thickness that covers the upper end joint surface 21a of the first flange 21. The flange protection plate 5 is ring-shaped in plan view. That is, the flange protection plate 5 has the same shape as the upper end joint surface 21a of the first flange 21 in plan view, and the outer diameter of the flange protection plate 5 also coincides with the upper end joint surface 21a. The outer peripheral portion 5c of the upper surface of the flange protection plate 5 has an outer peripheral convex portion 51 that is convex upward over the entire circumference. The flange protection plate 5 is detachably joined to the first flange 21 by a plurality of fixing bolts 52 arranged at intervals in the circumferential direction. A first recess 5b is formed at the tightening position of the fixing bolt 52 on the upper plate surface 5a of the flange protection plate 5 except for the area where the outer peripheral convex portion 51 is located. The head 52a of the fixing bolt 52 is housed in the first recess 5b. The fixing bolt 52 is fixed in a state where it does not protrude above the upper plate surface 5a of the flange protection plate 5.

[0035] When the monopile 2 is driven, a bottom surface 62a of a driving portion 62 of a monopile driving machine 60 abuts against the outer peripheral protrusion 51 of the flange protection plate 5 from above.

[0036] 7, a second recess 5d is formed in the upper plate surface 5a of the flange protection plate 5. A first hanger 53 for hanging the suspending wire W is provided inside the second recess 5d in a state where it does not protrude above the upper plate surface 5a of the flange protection plate 5. In addition, a second hanger 54 for hanging the suspending wire W is provided on the inner circumferential surface 5e of the flange protection plate 5. In this embodiment, the configuration includes both the first suspender 53 and the second suspender 54, but only one of them may be provided.

[0037] Next, as shown in Figures 4 and 9(a), the driving part 62 of the monopile driving machine 60 strikes the outer peripheral convex part 51 (see Figure 5) of the flange protection plate 5 from above, thereby driving the monopile 2 into the seabed G. At this time, the impact from the driving part 62 is directly received by the flange protection plate 5, so that the upper end joint surface 21a of the first flange 21 of the monopile 2 can be prevented from being damaged by the impact force of the driving part 62. After the monopile 2 has been driven to a predetermined depth, the flange protection plate 5 is removed from the upper end joint surface 21a.

[0038] 2 and 9(b), the upper end joint surface 21a of the first flange 21 of the monopile 2 is brought into liquid-tight surface contact with the lower end joint surface 31a of the second flange 31 of the wind turbine tower 3 from above, and the monopile 2 is bolted to the inside of the wind turbine tower 3. This joins the monopile 2 to the wind turbine tower 3, completing the assembly of the wind turbine 1.

[0039] Next, the operation of the above-mentioned construction method for the wind turbine 1 will be described in detail with reference to Figs. The construction method for the wind turbine 1 according to this embodiment is a method for connecting a monopile 2 driven into the seabed G to a wind turbine tower 3 made of a steel pipe installed on the monopile 2. The construction method for the wind turbine 1 includes the steps of attaching a flange protection plate 5 to a flat upper end joint surface 21a that is radially inward from the outer circumferential surface of the monopile 2, striking the flange protection plate 5 from above with a driving part 62 of a monopile driving machine 60 to drive the monopile 2 into the seabed G, removing the flange protection plate 5 from the upper end joint surface 21a, and bringing a lower end joint surface 31a of the wind turbine tower 3 into liquid-tight surface contact from above, and connecting the monopile 2 to the wind turbine tower 3 with bolts on the inside.

[0040] In this embodiment, the wind turbine tower 3 can be directly joined to the monopile 2 driven into the seabed G. When driving the monopile 2, the driving part 62 strikes the monopile 2 with the flange protective plate 5 attached to the upper end joint surface 21a of the monopile 2 for protection. Therefore, the upper end joint surface 21a of the monopile 2 can be protected by the flange protective plate 5 during driving, and the upper end joint surface 21a is not damaged by large repeated stress due to the impact energy of the driving part 62. As a result, when joining the wind turbine tower 3, the flange protective plate 5 can be removed from the upper end joint surface 21a, and then the lower end joint surface 31a of the wind turbine tower 3 can be brought into liquid-tight surface contact with the upper end joint surface 21a of the monopile 2. As described above, in this embodiment, the wind turbine tower 3 and the monopile 2 can be directly joined with the bolts 32, so that the transition piece that was conventionally used to be joined between the monopile 2 and the wind turbine tower 3 can be omitted, the number of steps required for construction can be reduced, and construction efficiency can be improved.

[0041] Moreover, in this embodiment, a first flange 21 is provided that protrudes radially inward around the entire circumference of the upper end of the monopile 2. The upper end joint surface 21a is the upper surface of the first flange 21. A second flange 31 is provided that protrudes radially inward around the entire circumference of the lower end of the wind turbine tower 3. The lower end joint surface 31a is the lower surface of the second flange 31. The flange protective plate 5 has a constant thickness that covers the upper end joint surface 21a of the first flange 21. By providing the first flange 21 on the monopile 2 and the second flange 31 on the wind turbine tower 3 in this way, it becomes easier to ensure flat joint surfaces 21a, 31a on the respective flanges 21, 31. In addition, the flange protective plate 5 can uniformly cover the entire upper end joint surface 21a of the first flange 21, which extends all around. Therefore, the impact force of the driving part 62 can be applied to the monopile 2 all around in a balanced and uniform manner, which makes it possible to prevent an unbalanced load from acting on the upper end joint surface 21a of the monopile 2 and to prevent deformation or damage to the upper end joint surface 21a.

[0042] In this embodiment, the flange protection plate 5 has an outer peripheral protrusion 51 that is convex upward on its outer periphery. The outer peripheral protrusion 51 is struck by the driving portion 62. Therefore, the driving-in portion 62 can be brought into contact only with the outer peripheral convex portion 51 of the flange protective plate 5 that protects the upper end joint surface 21a of the monopile 2. As a result, the effect of the impact force that the upper end joint surface 21a receives from the driving-in portion 62 can be reduced, and deformation or damage to the upper end joint surface 21a of the monopile 2 can be more effectively prevented.

[0043] In this embodiment, the flange protection plate 5 is joined to the first flange 21 by a fixing bolt 52. The fixing bolt 52 is fixed in a state where it does not protrude above the upper plate surface 5a of the flange protection plate 5. Therefore, by fastening the flange protection plate 5 to the first flange 21 of the monopile 2 with the fixing bolts 52, the flange protection plate 5 can be easily attached and detached from above the first flange 21. In this case, the flange protection plate 5 is securely fixed to the monopile 2, so that even when the driving-in part 62 strikes the monopile 2, the flange protection plate 5 can be prevented from shifting or coming off from the first flange 21. Furthermore, since the fixing bolts 52 do not protrude above the upper plate surface 5a of the flange protection plate 5, the problem of the driving-in part 62 interfering with the fixing bolts 52 can be eliminated.

[0044] In this embodiment, a recess 5d is formed in the upper plate surface 5a of the flange protection plate 5. A first hanger 53 for hanging the suspending wire W is provided inside the recess 5d without protruding above the upper plate surface 5a of the flange protection plate 5. Therefore, the flange protection plate 5 can be suspended by hanging the suspending wire W on the first hanger 53. Since the first hanger 53 does not protrude above the upper plate surface 5a of the flange protection plate 5, the driving portion 62 can be prevented from interfering with the first hanger 53.

[0045] In this embodiment, a second hanger 54 for hanging the suspending wire W is provided on the inner circumferential surface 5e of the flange protection plate 5. Therefore, the flange protection plate 5 can be suspended by hanging the suspending wire W on the second hanger 54. Since the second hanger 54 is attached laterally from the inner circumferential surface 5e of the flange protection plate 5 and does not protrude above the upper plate surface 5a of the flange protection plate 5, it is possible to prevent the driving portion 62 from interfering with the second hanger 54.

[0046] In addition, in this embodiment, an internal platform (not shown) for performing bolt fastening work is provided on the peripheral portion of the monopile 2, so that this internal platform can be used to easily perform bolt fastening between the monopile 2 and the wind turbine tower 3.

[0047] As described above, in the construction method for a wind turbine foundation without a transition piece according to this embodiment, the number of steps involved in assembling the wind turbine 1 can be reduced, and construction efficiency can be improved.

[0048] An embodiment of the construction method for a wind turbine foundation without a transition piece according to the present invention has been described above. However, the present invention is not limited to the above embodiment and can be modified as appropriate without departing from the spirit of the present invention.

[0049] For example, in this embodiment, the monopile 2 is provided with the first flange 21, and the wind turbine tower 3 is provided with the second flange 31, but the present invention is not limited to this type of flange. For example, instead of flanges extending all over the structure, protruding ribs for bolt fixing provided intermittently in the circumferential direction may be provided on the monopile 2 and the wind turbine tower 3, and the upper and lower joint surfaces of the respective protruding ribs may be brought into surface contact with each other for bolt connection.

[0050] In addition, in this embodiment, the first flange 21 is configured to protrude radially inward around the entire upper end of the monopile 2, but this is not limited to this, and the first flange may be configured to protrude radially outward around the entire upper end of the monopile 2, for example, so that the upper end of the monopile 2 is a T-shaped flange.

[0051] In addition, in this embodiment, the flange protection plate 5 is configured to have an outer peripheral convex portion 51 that convex upwards on the outer periphery, but such outer peripheral convex portion 51 can be omitted, and the driving portion 62 can be directly contacted with the upper plate surface 5a of the flange protection plate 5.

[0052] Furthermore, the joint surface protection member provided for the purpose of protecting the upper end joint surface 21a of the monopile 2 when driving the monopile 2 is not limited to being a ring plate-shaped flange protection plate 5 as in this embodiment, and other forms may be adopted.

[0053] Furthermore, in this embodiment, the flange protection plate 5 (joint surface protection member) is fixed to the first flange 21 of the monopile 2 by the fixing bolts 52, but it is also possible to adopt other fixing means, such as a pin inserted from above into a hole in the first flange 21. The point is that the joint surface protection member should be positioned relative to the first flange 21 so as not to shift in the planar direction.

[0054] Furthermore, in this embodiment, an example configuration is shown in which an external platform 4 (work scaffolding) is provided on the upper outer periphery of the monopile 2 for performing bolt fastening work, but such an external platform 4 may be omitted, or an outer periphery work scaffolding of another shape and configuration may be used.

[0055] In addition, the components in the above-described embodiments can be replaced with well-known components as appropriate without departing from the spirit of the present invention. [Explanation of symbols]

[0056] 1 windmill 2. Monopile 3. Windmill Tower 4 External platform (work platform) 5 Flange protection plate (joint surface protection material) 5a Upper plate surface 5d Second recess 5e Inner surface 21 First flange 21a Upper end joint surface 31 Second flange 31a Lower end joint surface 32 Volts 51 Outer periphery protrusion 52 Fixing bolt 53 First Lift 54 Second Lift 62 Drive-in section W Suspension wire

Claims

1. A construction method for a wind turbine foundation without a transition piece connecting a monopile driven into the ground and a wind turbine tower made of a steel pipe installed on the monopile, comprising: A step of attaching a joint surface protection member to a flat upper end joint surface formed at the upper end of the monopile; A step of striking the joint surface protection member from above with a driving unit of a monopile driving machine to drive the monopile into the ground; removing the joint surface protection member from the upper end joint surface; a step of bolting the lower end joint surface of the wind turbine tower to the upper end joint surface in liquid-tight surface contact from above; A construction method for a wind turbine foundation without a transition piece.

2. A first flange is provided around the entire upper end of the monopile, protruding radially inward or outward; the upper end joint surface is an upper surface of the first flange, A second flange is provided which overlaps the upper surface of the first flange and protrudes radially inward or outward around the entire circumference of the lower end of the wind turbine tower, the lower end joint surface is a lower surface of the second flange, 2. The construction method for a wind turbine foundation without a transition piece according to claim 1, wherein the joint surface protection member is a flange protection plate having a constant thickness that covers the upper end joint surface.

3. The flange protection plate has an outer peripheral protrusion that is upwardly protruding, The construction method for a wind turbine foundation without a transition piece according to claim 2 , wherein the outer circumferential convex portion is struck by the driving portion.

4. The flange protection plate is joined to the first flange by a fixing bolt, 4. The construction method for a wind turbine foundation without a transition piece according to claim 2 or 3, wherein the fixing bolts are fixed in a state where they do not protrude above an upper plate surface of the flange protective plate.

5. A recess is formed on the upper plate surface of the flange protection plate, 4. The construction method for a wind turbine foundation without a transition piece according to claim 2 or 3, wherein a hanging device for hanging a hanging wire is provided inside the recess in a state where it does not protrude above an upper plate surface of the flange protective plate.

6. 4. The construction method for a wind turbine foundation without a transition piece according to claim 2 or 3, wherein a suspender for hanging a suspender wire is detachably provided on an inner peripheral surface of the flange protective plate.

7. 3. The construction method for a wind turbine foundation without a transition piece according to claim 1 or 2, wherein a work scaffold is provided on a peripheral portion of the monopile.

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