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. 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, the annular gap being larger at the first end than the second end, pouring concrete into the annular gap in the formwork, wherein when the concrete is poured, the first end of the formwork is on a bottom side and the second end of the formwork is on a top side, curing the concrete such that the cured concrete forms a hollow structural element with a wall thickness having a taper resulting from the taper of the annular gap in the formwork, the hollow structural element having a first end face and a second end face, the first end face being cured adjacent to the first end of the formwork and the second end face being cured adjacent to the second end of the formwork, rotating the hollow structural element by 180 such that the second end face is on the bottom side and the first end face is on the top side, shipping the hollow structural element to an offshore installation site, and ramming or vibrating the hollow structural element with the second end face, as seen in an installed condition, into a seabed at the installation site.

2. The method according to claim 1, wherein the concrete is cured in an autoclave.

3. The method according to claim 1, wherein a wall of the hollow structural element is produced in a sliding formwork or in a climbing formwork.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The object is explained in more detail below with reference to a drawing showing examples of embodiments. The drawing shows:

(2) FIG. 1 is a wind turbine with a wind turbine foundation structure;

(3) FIG. 2 is a wind turbine foundation structure according to an embodiment example;

(4) FIG. 3 is a longitudinal section through a wind turbine foundation structure according to an embodiment example;

(5) FIG. 4 is a longitudinal section through a wind turbine foundation structure according to an embodiment;

(6) FIGS. 5a-f are schematic elevated views of longitudinal sections through wind turbine foundation structures according to embodiments;

(7) FIG. 6a, b are a detail of a stepped transition;

(8) FIG. 7 is the erection of a wind turbine foundation structure according to an embodiment example.

DETAILED DESCRIPTION

(9) 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.

(10) 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.

(11) 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.

(12) 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.

(13) 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.

(14) 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.

(15) 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.

(16) 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.

(17) 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.

(18) 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.

(19) 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.

(20) 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.

(21) 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.

(22) 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.

(23) 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.

(24) 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.

(25) 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

(26) 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

(27) 2 Wind turbine 4 foundation structure 6 seabed 8 Sea level 10 Transition piece 12 Wind turbine 14 Hollow structural element 14a upper face 14b lower face 16 web 18 collar 20 reinforcement 22 detail 24a fillet 24b Wedge 26 Vessel 28 Foundation tool