Foundation for a wind turbine

Abstract

An openwork load-bearing structure for a wind turbine, in particular a lattice-tower structure for a wind turbine, in particular a foundation structure for a wind turbine, in particular for anchoring an offshore wind turbine in the ground via driven foundation piles, wherein the openwork load-bearing structure has primary structures, via which loads which occur in the load-bearing structure as a result of the wind turbine are dissipated, and secondary structures, which perform functional, rather than load-dissipating, tasks, wherein the secondary structures are arranged on the primary structures and are connected integrally thereto, and wherein the integral connection between the primary and the secondary structures is in the form of a connecting layer arranged therebetween. Also, a method for producing a lattice-tower structure for a wind turbine, in particular a foundation structure for a wind turbine, in particular for anchoring an offshore wind turbine in the ground via foundation piles.

Claims

1. An openwork load-bearing structure for a wind turbine, wherein the openwork load-bearing structure comprises: primary structures via which loads which occur in the load-bearing structure as a result of the wind turbine are dissipated; and secondary structures, which only perform functional tasks and do not dissipate loads which occur in the load-bearing structure as a result of the wind turbine; wherein the secondary structures are arranged on the primary structures and are connected integrally thereto, wherein the integral connection between the primary structures and the secondary structures is in the form of a connecting layer arranged therebetween, and wherein said openwork load-bearing structure is a foundation structure, wherein one or more of the primary structures is a corner post or a leg, and wherein one or more of the secondary structures is a pile stopper for depth-limiting the corner post or leg when the corner post or leg is inserted into a driven foundation pile.

2. The openwork load-bearing structure according to claim 1, wherein the connecting layer is in the form of an adhesive layer.

3. The openwork load-bearing structure according to claim 1, wherein each of the secondary structures is secured to a sleeve, which positively fits one of the primary structures, and wherein the connecting layer is formed between the sleeve and the primary structure.

4. The openwork load-bearing structure according to claim 3, wherein the sleeve is of multipart design.

5. The openwork load-bearing structure according to claim 3, wherein the primary structure is tubular, and wherein the sleeve is formed as a part-shell.

6. The openwork load-bearing structure according to claim 5, wherein the sleeve together with other sleeves or together with one or more auxiliary shells forms a complete ring.

7. The openwork load-bearing structure according to claim 1, wherein the pile stopper completely encloses the corner post or the leg forming an annular gap, and wherein the connecting layer is arranged in the annular gap.

8. The openwork load-bearing structure according to claim 7, wherein the pile stopper is constructed of several part-annular segments.

9. The openwork load-bearing structure according to claim 1, wherein the pile stopper is constructed of a bottom pile stopper ring plate with a central through hole for the corner post or the leg, a cylindrical extension surrounding the through hole and arranged on the inside of the ring of the pile stopper ring plate, and several reinforcing fins, which are arranged extending radially outwardly between pile stopper ring plate and extension along a perimeter of the extension which is arranged substantially perpendicular on the pile stopper ring plate, and wherein the pile stopper ring plate is sized radially surmounting the foundation pile at the corner post or leg inserted in the foundation pile.

10. The openwork load-bearing structure according to claim 7, wherein spacers are arranged on the annular gap side cylindrical surface of the pile stopper, via which the corner post or the leg are kept at a distance from the pile stopper.

11. The openwork load-bearing structure according to claim 1, the further comprising one or more additional secondary structures selected from the group consisting of J tubes, platforms and docks for landing of boats, and work platforms.

12. A method for producing an openwork load-bearing structure for a wind turbine, wherein the load-bearing structure includes primary structures via which loads which occur in the load-bearing structure as a result of the wind turbine are dissipated, and secondary structures, which only perform functional tasks and do not dissipate loads which occur in the load-bearing structure as a result of the wind turbine, the method comprising integrally connecting at least one primary structure to a secondary structure by arranging a setting connecting layer between the at least one primary structure and the secondary structure, wherein the secondary structure is a pile stopper, and the primary structure is a corner post or leg.

13. The method according to claim 12, wherein the connecting layer is in the form of an adhesive layer.

14. The method according to claim 12, wherein the secondary structure is secured to a sleeve, which positively fits the primary structure, and wherein the connecting layer is formed between sleeve and primary structure.

15. The method according to claim 14, wherein the secondary structure is secured to the sleeve prior to connecting the sleeve to the primary structure.

16. The method according to claim 12, wherein, prior to connecting the pile stopper to the corner post or the leg, a measurement of the pre-driven foundation piles is performed to determine an appropriate location of the pile stopper at the corner post or leg, and wherein the pile stopper is secured at the appropriate location on the corner post or leg as determined by the measurement.

17. The method according to claim 12, wherein connecting devices are arranged in an area of the connecting layer with the use of grout for improving shear stability.

18. The method according to claim 12, wherein the method further comprises integrally connecting at least one primary structure to one or more additional secondary structures by arranging a setting connecting layer between the at least one primary structure and the one or more additional secondary structures, wherein the one or more additional secondary structures are selected from the group consisting of J tubes, platforms and docks for landing of boats, and work platforms.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, the invention is explained in detail with reference to several exemplary embodiments the principles of which are shown in the figures. In the drawings:

(2) FIG. 1 shows a schematic representation of a foundation structure according to the invention,

(3) FIG. 2 shows a detailed view of the section designated with X in FIG. 1 of an exemplary embodiment of a bonded pile stopper in sectional view,

(4) FIG. 3 shows an isometric view of the pile stopper shown in FIG. 2,

(5) FIG. 4 shows a detailed view of the section designated with Y in FIG. 1 of another exemplary embodiment of a grouted pile stopper,

(6) FIG. 5 shows an isometric view of the pile stopper shown in FIG. 4, and

(7) FIG. 6 shows a detail view of the section designated with Z in FIG. 1 of an exemplary embodiment of a connection according to the invention of a secondary structure with a primary structure in sectional view.

DETAILED DESCRIPTION OF THE INVENTION

(8) FIG. 1 shows a foundation structure 1 for a tower structure 2. This foundation structure 1 is a jacket for an offshore structure such as, for example, for an offshore wind turbine, which means that the jacket is anchored to the sea floor 6, wherein the foundation structure 1 is configured and arranged that its upper part is above sea level 7.

(9) The jacket consists of corner posts 3 and struts 4 which are arranged between the corner posts 3 and secured thereto. These components are load-dissipating parts, which are referred to as primary structures. The corner posts 3 are anchored via hollow foundation piles 5 in seabed 6, wherein the insertion depth of the corner posts 3 in the foundation piles 5 is limited by pile stoppers 8, 9. As will be shown later in detail, FIG. 1 shows two different pile stoppers, namely pile stopper 8 adhesively secured at the left corner post, pile stopper 9 connected by grout at the right corner post.

(10) FIG. 2 shows the section designated with X in FIG. 1 in enlarged and sectional representation. Shown is a corner post 3 which in a foundation pile 5 that is pre-driven into the seabed is grouted by a grout connection 26 with pile 5. Shear plates 27 are provided at the corner post 3 on the outside of the section entering pile 5. Furthermore, an insertion aid 22 is formed at the lower end of the corner post 3.

(11) A pile stopper 8 is resting on top of foundation pile 5. Pile side, pile stopper 8 has a supporting surface 24a via which the pile stopper plate 24 rests on pile 5. It further has reinforcing fins 24b, 24c, which extend downwardly (24b) or upwardly (24c) from the pile stopper plate 24. The pile stopper plate 24 is connected to the corner post 3 via an adhesive connection. For the sake of greater clarity the adhesive layer 28 establishing the adhesive connection is shown only in the left part of the pile stopper plate 24.

(12) FIG. 3 shows in isometric view the detail designated X in FIG. 1 that has already been described with reference to FIG. 2. Pile stopper 8 which is secured to the corner post 3 by means of an adhesive connection consists of a circular ring plate 24 having a central through hole for corner post 3, as can be seen from FIG. 2. This through-hole is sized so that corner post 3 and pile stopper 8 form an intermediate annular gap, in which an adhesive is placed to form an adhesive layer 28. For this annular gap to be formed as uniformly as possible, there are provided spacers in the form of circumferential annular beads on the annular gap side surface of the pile stopper, i.e., on the surface facing corner post 3. After placing the adhesive composition into the annular gap and after curing or setting of the adhesive composition corner post 3 and the pile stopper are connected. Here, the adhesive may be chosen so that the connection still has a certain elasticity, so that pile stopper 8 can still move elastically to some extent in the longitudinal direction of corner post 3.

(13) Ring plate 24 of corner post 3 rests on its bottom 24a on foundation piles 5. On the upper side of ring plate 24 a cylindrical sleeve 29 is secured substantially perpendicular to ring plate 24 and stabilized by means of stiffening fins 24c. In the exemplary embodiment shown, pile stopper 8 is composed of four 90 ring segments 8a to 8d. These ring segments 8a to 8d are bolted together at the pairwise butting interfaces. For this purpose, holes 30 are provided for the passage of bolts in the reinforcing fins 24c resting adjacently.

(14) Four holes 31 are provided in ring plate 24 which enable the escape of sea water when filling grout 26 into foundation piles 5 and also allow observation of the pile inside, e.g., by remote-controlled cameras to monitor the gradual filling of pile 5 with grout 26. At least one electrical grounding cable 32 is provided for establishing a conductive contact between corner post 3 and pile stopper 8. Ring plate 24 resting directly on pile 5 ensures a conductive connection between these two components. In addition, however, further grounding can be made by providing an appropriate grounding cable.

(15) FIGS. 4 and 5 show an alternative design of a pile stopper 9. In the sectional view of FIG. 4 it can be seen that annular gap 33 between corner post 3 and pile stopper is significantly larger than that of the adhesive variant. This annular gap 33 is filled with a grout composition to secure pile stopper 9 to corner post 3, and after setting of grout composition 34, there is a strong connection between corner post 3 and pile stopper 9. This connection can be further improved in strength by forming shear plates 35 on the corner post side inner surface of the pile stopper 9. Corner post 3 also has functionally identical shear plates 27 on its end section on the side of the anchoring. These shear plates 35 and 27 allow for a more stable connection with both grout 34 filled into annular gap 33 and with grout 26 filled into pile 5.

(16) Moreover, pile stopper 9 which is connected by the grouting also consists of a base plate 40 and a cylinder 41 arranged perpendicular thereto, which encloses the central opening in base plate 40, and together with corner post 3 forms annular gap 33. Again, a grounding cable 32 is installed between corner post 3 and pile stopper in order to establish an electrically conductive connection. Pile stopper 9 of FIG. 5 also consists of four 90 segments 40a to 40d, which are secured by bolts to one another to form a 360 pile stopper. However, other segmentations are conceivable, e.g., a subdivision into two, three, or more than four segments. The division into segments is advantageous because it makes handling much easier.

(17) Unlike in the prior art, securing of pile stopper 8 or 9 to corner post 3, can be carried out immediately before securing the lattice tower structure 1 to foundation piles 5. The height up to which the foundation piles 5 protrude from the seabed 6, can be measured and thus the desired height position of pile stoppers 8, 9 at corner post 3 can be determined. In this desired position pile stoppers 8, 9 can be secured to corner post 3 by adhesion (8) or by grouting (9), and after setting of the connection, the lattice tower structure 1 can be lowered onto foundation piles 5, and the lower end 22 of the corner posts 3 (Groutzapfen) inserted in the foundation piles 5 until pile stoppers 8, 9 come to rest on the upper edges of foundation piles 5. In the case of welded joints known from the prior art, a direct establishment of the connection between pile stopper and corner posts at the construction of the tower is not possible, since welds are more complicated to establish. Welds must also be subjected to testing and usually must be accepted by the person issuing the certification. Since adhesive and grout connections usually do not have these disadvantages, the pile stopper can be connected directly to the corner post at the installation site or just prior to loading for shipment at sea, and thus, for example, the use of compensation plates for height adjustment is avoided.

(18) FIG. 6 shows an enlarged view of the section designated Z in FIG. 1. It shows the attachment of a J tube 10 to a corner post 3 via a sleeve 11. An annular collar 11 is placed around the tubular corner post 3, with an annular gap remaining between corner post 3 and sleeve 11 which is filled with an adhesive composition 12. After setting of this connecting layer forming adhesive composition 11 there is a fixed connection between sleeve 11 and corner post 3 which does not affect the stability of corner post 3. J tube 10 is welded to sleeve 11.

(19) Sleeve 11 can be composed of multiple subrings. Conceivable are, for example, two 180 subrings, three 120 subrings, or four 90 subrings. Combinations of different subrings are possible, too. It is also possible that sleeve 11 surrounds tubular corner post 3 only at a portion of the circumference, for example, by 90. The size of the adhesive surface must merely meet the stability requirements for securing the secondary structure. These requirements are less, for example, in case of a J tube 10 compared to a working platform. In case of high stability requirements, therefore, a sleeve 11 surrounding the corner post 3 completely is preferred.