WIND TURBINE FOUNDATION STRUCTURE, AND METHOD FOR PRODUCING A WIND TURBINE FOUNDATION STRUCTURE

Abstract

A wind turbine foundation structure comprising a hollow structural member having a longitudinally extending circumferential wall, the wall being bounded at the top by a top end face and bounded at the bottom by a bottom end face, wherein the wall is formed from a mineral building material and in that a wall thickness of the wall tapers from the top end face towards the bottom end face.

Claims

1-15. (canceled)

16. A wind turbine foundation structure comprising: a hollow structural element having a longitudinally extending circumferential wall, the wall being bounded at a top by a top end face and bounded at a bottom by a bottom end face, with the wall which is formed from a mineral building material, and wherein a wall thickness of the wall tapers from the upper end face, in the installed condition, toward the lower end face, in the installed condition.

17. The wind turbine foundation structure according to claim 16, further comprising at least one of: the hollow structural element is hollow cylindrical, or the wall thickness of the wall tapers continuously along at least a part of a longitudinal extension of the hollow structural element, or the wall thickness of the wall tapers in steps along at least a part of a longitudinal extension of the hollow structural element.

18. The wind turbine foundation structure according to claim 16, further comprising at least one of: the hollow structural element has an inner diameter and the inner diameter increases due to tapering, or the hollow structural element has an outer diameter and the outer diameter decreases due to tapering.

19. The wind turbine foundation structure according to claim 16, further comprising at least one of: the building material contains cement, or the building material has a water/cement ratio of less than 0.45, or the building material has a strength class of at least C40/50 according to EN 206 and EN 1992, or the building material has a pore content of air voids of less than 5%, or the building material has a cement content of at least 350 kg/m.sup.3, or in a mercury pressure porosimetric measurement, the building material has a porosity P.sub.28d of less than 12 vol %, and P.sub.90d of less than 10 vol %.

20. The wind turbine foundation structure according to claim 16, wherein the wall is mechanically prestressed with a prestressing force of more than 5% of a compressive strength of the wall.

21. The wind turbine foundation structure according to claim 16, further comprising at least one of the following: the building material is metal-reinforced, or the building material comprises concrete reinforced with a reinforcement, and the reinforcement, at 98% of all measuring points, has not less than 26 mm concrete cover, or the building material is reinforced with ferritic stainless reinforcing steel having a chromium content which does not exceed 18 M %, and optionally contains molybdenum, or the building material is reinforced with austenitic stainless reinforcing steel which contains at least 5 M % to 14 M % nickel and 12 M % to 22 M % chromium, or the building material is reinforced with ferritic-austenitic stainless reinforcing steel which contains at least 18 M % chromium, 2 M % to 8 M % nickel, and optionally molybdenum.

22. The wind turbine foundation structure according to claim 16, wherein the top end face is metallically reinforced.

23. The wind turbine foundation structure according to claim 22, wherein a metallic reinforcement projects out of the top end face.

24. The wind turbine foundation structure according to claim 23, wherein the metallic reinforcement projects out of the top end face completely circumferentially out of the top end face.

25. The wind turbine foundation structure according to claim 16, wherein the hollow structural element is reinforced with a reinforcement, and a density of the reinforcement in an end region of the hollow structural element is greater than in a central region of the hollow structural element.

26. The wind turbine foundation structure according to claim 16, wherein an inner diameter of the wall in an end region of the hollow structural element increases towards the top end face.

27. The wind turbine foundation structure according to claim 26, wherein the inner diameter of the wall increases conically.

28. The wind turbine foundation structure according to claim 16, wherein a radially inwardly pointing stop is formed on an inner lateral surface of the wall in an end region of the hollow structural element.

29. The wind turbine foundation structure according to claim 16, wherein a radially outwardly facing collar is formed on an outer lateral surface of the wall in an end region of the hollow structural element.

30. The wind turbine foundation structure according to claim 16, wherein the building material is sealed.

31. The wind turbine foundation structure according to claim 30, wherein the building material is sealed with a sealing foil.

32. A method of manufacturing a wind turbine foundation structure, the method comprising: building up a formwork on-shore, wherein an annular gap in the formwork tapers from a first end towards a second end, pouring concrete into the annular gap in the formwork, curing the concrete such that the cured concrete forms a hollow structural element, shipping the hollow structural element to an offshore installation site, and ramming or vibrating the hollow structural element with a lower end face, as seen in an installed condition, into a seabed at the installation site.

33. The method according to claim 32, wherein the concrete is cured in an autoclave.

34. The method according to claim 32, wherein a wall of the hollow structural element is produced in a sliding formwork or in a climbing formwork.

35. The method according to claim 32, wherein: the first end of the formwork is on a bottom side and the second end of the formwork is on a top side, that the hollow structural element is rotated by 180° after curing and is then founded, and the hollow structural element is shipped to the offshore installation site in an upright position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The object is explained in more detail below with reference to a drawing showing examples of embodiments. The drawing shows:

[0056] FIG. 1 is a wind turbine with a wind turbine foundation structure;

[0057] FIG. 2 is a wind turbine foundation structure according to an embodiment example;

[0058] FIG. 3 is a longitudinal section through a wind turbine foundation structure according to an embodiment example;

[0059] FIG. 4 is a longitudinal section through a wind turbine foundation structure according to an embodiment;

[0060] FIGS. 5a-f are schematic elevated views of longitudinal sections through wind turbine foundation structures according to embodiments;

[0061] FIG. 6a, b are a detail of a stepped transition;

[0062] FIG. 7 is the erection of a wind turbine foundation structure according to an embodiment example.

DETAILED DESCRIPTION

[0063] FIG. 1 shows a wind turbine 2, which is founded offshore. All statements made here apply to both offshore foundation structures and onshore foundation structures.

[0064] The wind turbine 2 is founded in a seabed 6 via a wind turbine foundation structure 4. The foundation structure 4 is founded into the seabed with an embedment length 4a. The foundation structure extends above the water surface 8 with a length 4b. The foundation structure is connected to a transition piece 10, for example via a grout connection, which is conventionally known.

[0065] A wind turbine 12 is arranged on the transition piece 10 here as an example, but a sub-station, a transformer station or the like may also be provided. For the foundation of the foundation structure 4, it is driven or vibrated into the seabed 6.

[0066] For the present purpose, it is now proposed that the foundation structure 4 is formed of a hollow structural element 14 as shown in FIG. 2. The hollow structural element 14 is cast from concrete and has an upper end face 14a and a lower end face 14b. The hollow structural element 14 is preferably hollow cylindrical. The wall thickness of the hollow structural element 14 decreases from the upper end face 14a to the lower end face 14b. This may facilitate a grounding in the seabed 6.

[0067] The two distal ends of the hollow structural element 14 are shown enlarged 1 in FIG. 3. At the upper end face 14a of the hollow structural element 14, a circumferential web 16 may protrude from the upper end face 14a. This web 16 may be used to absorb pile driving forces or vibrations from the foundation tool. The web 16 is preferably formed of steel and is considerably more ductile than the concrete of the hollow structural element 14. During pile driving or vibration, the forces are absorbed by the web 16 and uniformly transmitted into the hollow structural element 14. This prevents damage to the upper end surface 14a.

[0068] A circumferential collar (also called an apron) 18 may be provided in the region of the upper end. The circumferential collar 18 may be formed as a landing structure, web or the like. The collar 18 may be spaced in the axial direction from the upper end surface 14a.

[0069] FIG. 3 further shows that the hollow structural member 14 terminates with a lower end face 14b at the lower end. The lower end face 14b has a smaller radial extent than the upper end face 14a. This is from the taper of the hollow structural element 14 from the upper end surface 14a to the lower end surface 14b. A wedge 20 may be provided at the lower end face 14b, which may be formed of steel, for example. A ground may be simplified over this wedge. The elements 16, 18 and 20 are optional.

[0070] FIG. 4 shows the hollow structural element 14 according to FIG. 3 with its upper end, a central region and its lower end. In the longitudinal section, the reinforcements 20 are drawn. It can be seen that the density of the reinforcement 20 is higher in the upper as well as in the lower end than in a center region.

[0071] The taper from the upper end face 14a to the lower end face 14b may be different, as shown in FIGS. 5a-f. It should be noted here that the figures are shown purely schematically and are highly exaggerated to illustrate the principle of the taper. The drawings are neither to scale nor do they show the correct relation of the sizes to each other. Rather, the drawings are merely intended to illustrate the principle.

[0072] FIG. 5a shows the hollow structural element 14, in which a diameter of an inner shell surface increases steadily from the upper end surface 14a toward the lower end surface 14b. The diameter of the outer shell surface is constant.

[0073] In FIG. 5b, it is shown that an inner diameter of the inner shell surface increases stepwise from the upper end face 14a toward the lower end face 14b. The diameter of the outer shell surface is constant.

[0074] FIG. 5c shows that the diameter of the outer lateral surface decreases steadily from the upper end face 14a to the lower end face 14b. The diameter of the inner lateral surface is constant.

[0075] FIG. 5d shows how the diameter of the outer lateral surface decreases in steps from the upper end face 14a to the lower end face 14b. The diameter of the inner shell surface is constant.

[0076] FIG. 5e shows how the diameter of the inner shell surface increases steadily from the upper end face 14a toward the lower end face 14b, and the diameter of the outer shell surface decreases steadily.

[0077] FIG. 5f shows how the inner diameter increases in steps from the upper end face 14a toward the lower end face 14b, and the diameter of the outer shell surface decreases in steps.

[0078] A detail 22 of a step is shown in FIGS. 6a and b. A step according to FIG. 5b, 5d or 5f may be formed as a fillet 24a as shown in FIG. 6a. A step may be formed as a wedge-shaped 24b, as shown in FIG. 6b.

[0079] FIG. 7 shows a method of founding a hollow structural element 14 at sea. First, the hollow structural elements 14 are cast from concrete using slipform and jumpform methods and dried in an upright position. Then, the hollow structural elements 14 are rotated once by 180° and loaded onto a ship 26. 20

[0080] Standing upright on the ship 26, the hollow structural elements are shipped to an installation site where they are founded using a suitable foundation tool 28. The hollow structural elements 14 are already supported on the ship 26 in such a way that the lower end face 14b is at the bottom and the upper end face 14a is at the top, 25 so that during foundation the lower end face 14b is placed on the seabed 6 and by means of the foundation tool 28 the hollow structural element 14 is rammed into the seabed.

LIST OF REFERENCE SIGNS

[0081] 2 Wind turbine [0082] 4 foundation structure [0083] 6 seabed [0084] 8 Sea level [0085] 10 Transition piece [0086] 12 Wind turbine [0087] 14 Hollow structural element [0088] 14a upper face [0089] 14b lower face [0090] 16 web [0091] 18 collar [0092] 20 reinforcement [0093] 22 detail [0094] 24a fillet [0095] 24b Wedge [0096] 26 Vessel [0097] 28 Foundation tool