MONOPILE FOUNDATION, ASSEMBLY OF A MONOPILE FOUNDATION AND METHOD OF ERECTING A MONOPILE FOUNDATION
The invention relates to a monopile foundation for an offshore structure, in particular for a wind turbine, with a foundation pile for supporting the structure and a foundation reinforcement adjoining the foundation pile on the outside, wherein the foundation reinforcement has a sleeve, a collar and at least one support, wherein the sleeve is associated with the foundation pile and the collar is held at a distance outwards from the sleeve by the at least one support, wherein the foundation pile has a foundation portion for introduction into the seabed and a reinforcement portion for connecting the foundation pile to the sleeve above the seabed, and wherein the collar is designed for at least partial introduction into the seabed.
Furthermore, the invention relates to a monopile foundation installation for an offshore structure, in particular for a wind turbine, with such a monopile foundation anchored in a seabed.
Furthermore, the invention relates to a method for erecting a monopile foundation installation with such a monopile foundation.
Different variants are known for the foundation structure of offshore structures, such as wind turbines in particular.
For water depths between 4 m and 50 m, so-called monopiles in particular, i.e., individual foundation piles, have proven to be an economical solution.
This type of foundation is usually a foundation pile in the form of a steel tube with a diameter of a plurality of metres, which is rammed with its open end into the seabed or inserted into the seabed using a vibration method.
In order to ensure sufficient stability of the foundation pile that supports the structure, in particular the wind turbine, the foundation pile is usually driven into the seabed over at least approximately half its length, for instance by 15 m —50 m.
However, this is only possible with reasonable effort in sandy or cohesive soils.
For the construction of offshore structures in places where it is to be expected that the foundation pile will hit rock when it is introduced into the seabed, additional measures have been taken to reduce the embedment length or depth of penetration of the foundation piles into the seabed without significantly impairing the rigidity of the monopile foundation.
For this purpose, a foundation reinforcement has been proposed in WO 2016/198272 A1 or also in the publication US 2005/0083783 A1, which has a sleeve lying on the outside of the foundation pile and a collar partially embedded in the seabed.
The collar and the sleeve are held at a predetermined distance from one another by means of supports.
The foundation reinforcement thus forms a kind of base for the foundation pile accommodated in the sleeve, which increases the rigidity of the foundation and supports the foundation pile against swaying movements on the seabed.
Therefore, the embedment length of the foundation pile in the seabed can be decreased.
The corresponding monopile foundation is erected by first driving the foundation reinforcement with the collar into the seabed.
The foundation pile is then passed through the sleeve of the foundation reinforcement, which protrudes upwards from the seabed and opposite the collar, and is driven into the seabed.
This can be done by vibration or by ramming.
After the foundation pile has been driven into the seabed, the gap between the foundation pile and the sleeve is filled in.
However, even monopile foundations that can be driven deep enough into sandy seabeds and therefore do not require foundation reinforcement can loosen over time.
A foundation pile can loosen, for example, as a result of rhythmically occurring loads that can be caused by wind and/or waves.
Alternatively or additionally, the sea current can be accelerated in the vicinity of the foundation piles, such that the seabed is eroded and depressions in the seabed, for example “scours”, are formed.
Measures must then be taken to ensure the stability of the offshore structure.
In addition, it is difficult to determine whether the foundation pile can be driven into the seabed to the desired length during founding.
Even if the seabed is in itself sandy and well suited for founding monopile foundations, it can happen that the foundation pile hits rock, for example in the form of erratics.
It is also conceivable for soils to be denser and more rigid than expected and therefore the selected installation device is not powerful enough for the installation.
This can prevent the desired embedment depth of the foundation pile in the seabed from not being reached.
Monopiles therefore cannot yet in every case be satisfactorily founded.
The present invention is therefore based on the object of designing and developing the monopile foundation, the monopile foundation installation and the method of the type mentioned at the beginning and previously explained in more detail in such a way that a satisfactory foundation can be achieved for those foundation piles whose original installation turned out to be inadequate because the desired embedment depth is reduced due to unknown rock or because the monopile foundation loosens over time.
This object is achieved with a monopile foundation according to the preamble of claim 1 in that each reinforcement element has a sleeve element of the sleeve, a collar element of the collar and at least one support element of the support.
The stated object is also achieved according to claim 9 by a monopile foundation installation for an offshore structure, in particular for a wind turbine, with a monopile foundation anchored in a seabed according to any one of claims 1 to 8, wherein the foundation pile is introduced into the seabed with its foundation portion, wherein the collar is at least partially, in particular completely, introduced into the seabed, wherein the foundation reinforcement has a plurality of, in particular two, three or four, reinforcement elements arranged next to one another in the circumferential direction of the foundation pile and wherein the sides of the reinforcement elements that are adjacent to one another in the circumferential direction are connected to one another in a positive-locking, articulated and/or force-fitting manner.
Furthermore, the aforementioned object is achieved according to claim 13 by a method for erecting a monopile foundation installation according to one of claims 9 to 12 with a monopile foundation according to one of claims 1 to 8,
- in which the foundation pile with the foundation portion is driven into the seabed, preferably by vibration and/or pulse ramming,
- in which, in the circumferential direction of the foundation pile, the collars of a plurality of, in particular two, three or four, reinforcement elements are at least partially introduced into the seabed, preferably by vibration,
- in which the reinforcement elements are then positioned next to one another by at least partial introduction into the seabed, in particular successively, or before at least partial introduction into the seabed,
- in which the mutually adjacent sides of the adjoining reinforcement elements are connected to one another, preferably by at least partial introduction into the seabed or before at least partial introduction into the seabed, in a positive-locking, articulated and/or force-fitting manner, and
- in which the reinforcement portion of the foundation pile above the seabed is connected to the sleeve of the foundation reinforcement.
The multi-part design of the foundation reinforcement enables a monopile foundation to be retrofitted with a foundation reinforcement whenever this is indicated for the respective reasons in the individual case.
Retrofitting with a one-piece foundation reinforcement would be unthinkable, since a one-piece foundation reinforcement could no longer be pulled over the foundation pile after installing the offshore structure, for example because attachments such as boat mooring fenders and ladders would be in the way.
Thanks to the multi-part design of the foundation reinforcement, it is, however, possible to subsequently introduce the individual reinforcement elements from the outside and then nevertheless connect the individual reinforcement elements to form a common foundation reinforcement.
However, this can be done in different ways in each case in a positive- locking, articulated and/or force-fitting manner.
The individual reinforcement elements are distributed in the circumferential direction around the foundation pile and are thus connected to one another in a direction perpendicular or transverse to the longitudinal axis of the foundation pile. The connection is preferably provided in such a way that the adjacent reinforcement elements are fixed or locked to one another both in the circumferential direction and in the radial direction, starting from the longitudinal axis of the foundation pile. In order to keep installation effort low, it is particularly preferred in this connection if only two, three or four reinforcement elements are provided and joined together to form a foundation reinforcement. With regard to the monopile foundation installation for offshore structures, in particular for a wind turbine, this means that on the one hand the foundation pile is introduced with its foundation portion into the seabed and on the other hand the collar is at least partially placed in the seabed in order to support the foundation reinforcement in the seabed. The foundation reinforcement is made up of reinforcement elements which are distributed around the foundation pile in the circumferential direction and are adjacent to one another in the circumferential direction. For the reasons mentioned, it is preferred if no more than two, three or four reinforcement elements form the foundation reinforcement. The reinforcement elements are connected to one another in a positive-locking, articulated and/or force-fitting manner on sides of the respective adjacent reinforcement elements that are adjacent to one another in the circumferential direction. Due to the multi-part design of the foundation reinforcement, the advantages of the monopile foundation and the monopile foundation installation are utilised to a particular extent when the foundation pile is inserted into the seabed with the foundation portion and only then are the collars of a plurality of, in particular two, three or four, reinforcement elements successively or jointly and at least partially introduced into the seabed in the circumferential direction of the foundation pile. In this case, the foundation pile and/or the reinforcement elements can preferably be embedded using the vibration method or by pulse ramming. Alternatively, the foundation pile and/or the reinforcement elements can also be driven by water-jetting into the seabed or embedded in the seabed in some other way. Installation effort can be further reduced if the reinforcement elements are successively positioned next to one another by at least partial introduction into the seabed and the adjacent sides of the adjacent reinforcement elements are connected to one another in a positive-locking and/or force-fitting manner. In this case, it is particularly simple and expedient if the mutually adjacent reinforcement elements are connected to one another by at least partial introduction into the seabed. However, installation effort can also be further reduced if the reinforcement elements are already positioned relative to one another, in particular connected to one another, before they are introduced into the seabed. If necessary, the mutually adjacent sides of the adjoining reinforcement elements can be connected to one another in a positive and/or force-fitting manner.
However, it is alternatively or additionally particularly simple and expedient for mutually adjacent reinforcement elements to be connected to one another in articulated manner on the sides facing one another.
In the case of an articulated connection, it is possible, for example, to place a reinforcement element on the foundation pile and to pivot another reinforcement element about the corresponding joint in such a way that the further reinforcement element is also placed on the foundation pile.
It is particularly useful if the articulated connection or the pivot connection defines a pivot axis which is at least predominantly or at least substantially parallel to the longitudinal axis of the foundation pile.
The reinforcement elements therefore remain, if required, at least substantially in a common plane perpendicular to the longitudinal extent of the foundation pile, even when they are pivoted relative to one another.
In this way, it is easily possible to place the reinforcement elements more than 180° around the foundation pile and to do this before the reinforcement elements are introduced into the seabed.
This can namely simplify the introduction of the reinforcement elements into the seabed.
If the reinforcement elements are already firmly connected to one another before they are introduced into the seabed, whether in a positive-locking, articulated and/or force-fitting manner, it is possible to avoid the connection of the reinforcement elements to one another being accidentally not as desired on introduction into the seabed or as a result of introduction into the seabed.
In addition, the reinforcement portion of the foundation pile above the seabed is connected to the sleeve of the foundation reinforcement.
In this case, a preferred load dissipation is achieved if the sleeve is arranged in a region above the seabed and preferably also at least partially above the collar.
For the sake of clarity and to avoid unnecessary repetition, the monopile foundation, the monopile foundation installation and the method are described together below, without always distinguishing in detail between the monopile foundation, the monopile foundation installation and the method.
For the person skilled in the art, however, it is clear from the context which features are particularly preferred in each case with respect to the monopile foundation, the monopile foundation installation and the method.
In a first particularly preferred embodiment of the monopile foundation, the sleeve and/or the collar has a circular or oval cross section.
A circular cross-section allows for a very even dissipation of forces from the foundation pile via the foundation reinforcement to the seabed.
However, in some cases there will be a dominant wave or wind direction, such that the forces introduced into the foundation pile have a preferential direction.
In this case, it may be expedient to use a sleeve and/or a collar with an oval cross-section.
This applies in particular when the greater lengthwise extent of the oval cross-section points in the preferential direction of the forces introduced into the foundation pile.
In the present case, the cross section is preferably arranged at least substantially in the horizontal.
In the at least substantially vertical direction, the sleeve and/or the collar can alternatively or additionally be of annular, cylindrical or conical design.
In this way, a very rigid foundation reinforcement will be obtained, which is also particularly suitable for dissipating the forces to the seabed.
Which shape of sleeve and/or collar is to be preferred depends on the type and direction of the forces to be dissipated, on the type of offshore structure supported by the foundation pile and, if applicable, on manufacturing and transport requirements.
In order to achieve appropriate reinforcement of the foundation pile, it is possible for the foundation reinforcement, the reinforcement elements, the sleeve and/or the collar to extend circumferentially around the foundation pile over an angular range of at least 60°, preferably at least 120°, more preferably at least 180°, in particular at least 260°. Extending around the foundation pile over a smaller angular range can be sufficient if the foundation pile only has to be supported in certain directions.
The greater the corresponding angular range, the more extensively and in all the more directions can the foundation pile be supported.
Depending on the particular seabed, a larger angular range can to a certain extent complicate or even prevent introduction into the seabed.
A very stable monopile foundation for uniformly dissipating forces can be obtained if the sleeve, the collar and/or the foundation pile are designed at least substantially concentrically with one another.
In addition, a stable foundation pile that is easy to set up can be obtained if the pile takes the form of a hollow profile.
For the sake of simplicity and for better force dissipation, the corresponding hollow profile can be cylindrical or conical, depending on the particular erection site and/or depending on the particular offshore structure supported by the foundation pile.
In order to simplify modular construction as well as the successive introduction of the reinforcement elements into the seabed, each of the reinforcement elements has a sleeve element of the sleeve, a collar element of the collar and at least one support element of the support.
For example, the foundation reinforcement can also be formed by identical reinforcement elements.
The use of identical parts is not only simpler, but also involves lower manufacturing costs.
In addition, installation of the foundation reinforcement can be simplified if the sides of the sleeve elements, collar elements and/or support elements that are adjacent to one another in the circumferential direction are designed for positive-locking, articulated and/or force-fitting connection to one another.
This also leads to an overall reduction in production costs for the foundation reinforcement.
A grout connection can be provided in order to achieve reliable support of the foundation pile on the foundation reinforcement, which allows the transmission of high forces.
For this purpose, a gap can be provided between the sleeve, in particular between the sleeve elements, and the outside of the reinforcement portion of the foundation pile, which gap can then be filled in with a casting compound.
What is known as a grout, which is a special concrete or cement paste or cement mortar for filling gaps, is particularly suitable for this purpose, in particular for connecting concentric steel tubes of a wind turbine that are spaced apart from one another by a gap.
Grouts with different compositions are known on the market.
Casting compounds can also be casting mortar.
A grout is, for example, a high-strength casting concrete that is known in different compositions.
Since grout connections are known in offshore wind turbines, albeit at a different location, in particular in the connection between the foundation pile and the tower of the wind turbine above water level, the present connections are also referred to as grout connections, although in principle other casting compounds can also be considered as a grout for forming the connection, for example steel fibre concrete or cement-free bentonite suspensions.
In particular, in order to obtain a radially closed gap that can be filled with a sealing compound, in particular a grout, it is advisable for at least two adjacent sleeve elements of adjacent reinforcement elements to be designed to overlap in portions in the circumferential direction.
A stable and also rigid design of the foundation reinforcement can be obtained if the at least one support, in particular the at least one support element, takes the form of a rib or strut.
In this way, forces in the radial direction can also be dissipated particularly reliably, in particular when the rib or strut extends in the radial direction.
The respectively adjoining support elements of adjacent reinforcement elements can also be designed for positive- locking, articulated and/or force-fitting engagement with one another, such that the adjacent reinforcement elements can be simply connected to one another.
The positive interlocking of the support elements is achieved particularly easily and reliably in that one support element has at least one hook portion and that the associated support element of the adjacent reinforcement element has at least one engagement portion that engages in the hook portion of the adjacent support element.
In the event that the foundation pile has a lead-through opening or a plurality of lead-
through openings, for example in order to lead a line and/or a cable through the lead- through opening into the foundation pile from the outside, it is advisable for the adjacent sleeve elements to be arranged spaced apart from each other in the foundation pile are at least in the region of at least one lead-through opening.
This prevents the at least one line and/or the at least one cable from being damaged by the foundation reinforcement.
This does not mean that the adjacent sleeve elements cannot be in contact with one another in portions, nor that the adjacent sleeve elements cannot be connected to one another.
However, this should then be the case in regions other than in the region of the at least one feedthrough opening.
Alternatively or additionally, a recess can also be provided in the collar at the points at which cables are routed to the foundation pile.
However, configurations are also conceivable in which the adjoining reinforcement elements, sleeve elements, collar elements and/or support elements are not connected to one another.
It is also possible to dispense with a grout and/or casting compound between the sleeve and the foundation pile in the corresponding regions of the lead- through.
For example, to prevent the seabed from being washed away in the region of the monopile foundation, the support can be designed as an annular disc that at least substantially closes the radial gap between the sleeve and the collar.
Entrainment of sediment from the inner region of the collar or the formation of a scour can be prevented in this way.
For a simple modular configuration of the foundation reinforcement, the support elements can be designed as annular disc elements of the annular disc.
For additional stiffening of the foundation reinforcement, the space between the collar and the foundation pile below the annular disc can also alternatively or additionally be filled at least substantially with a casting compound, in particular with grout.
In order to achieve simple and inexpensive filling in of free spaces with grout or another casting compound, the sleeve, in particular at least one sleeve element, and/or the support, in particular a support element, can have at least one grout port for connection to a grout line and supply of grout or another casting compound.
The position of the grout port can be selected depending on which free space is to be filled with a casting compound, in particular a grout.
In order to achieve simple and cost-effective filling in of free spaces with a casting compound, in particular a grout, the foundation pile can alternatively or additionally have a grout line on the inside.
This applies in particular when the grout line is connected to the at least one grout port.
In a first particularly preferred embodiment of the monopile foundation installation, each reinforcement element comprises a sleeve element of the sleeve, a collar element of the collar and at least one column element of the column.
In this way, modular construction of the foundation reinforcement can be achieved easily and inexpensively.
If necessary, even the construction of the foundation reinforcement can be carried out using identical parts that can be manufactured inexpensively.
The sides of the sleeve elements, collar elements and/or support elements that are adjacent to one another in the circumferential direction can be connected to one another in a positive-locking, articulated and/or force- fitting manner in order to achieve simple installation of the foundation reinforcement and to provide elevated stability and rigidity of the foundation reinforcement.
Particularly extensive and reliable reinforcement of the foundation pile can be achieved if the sleeve, in particular the sleeve elements, is/are connected to the outside of the reinforcement portion of the foundation pile via a grout connection.
This avoids unwanted play and simplifies installation.
Alternatively or additionally, at least two adjacent sleeve elements of adjacent reinforcement elements can be arranged overlapping in portions in the circumferential direction.
This can serve to stiffen the foundation reinforcement, as well as for filling in the gap between the sleeve and the foundation pile with a casting compound, in particular a grout.
For filling in the gap between the sleeve and the foundation pile with a casting compound, in particular a grout, it is also in principle possible for the sleeve elements to form a sleeve that is closed in the radial direction.
It is also useful for simplified installation and stiffening of the foundation reinforcement for adjacent support elements of adjacent reinforcement elements to engage in each other in a positive-locking, articulated and/or force-fitting manner, in particular via a hook portion.
Alternatively or additionally, the space between the collar, the foundation pile and the seabed below the annular disc can be at least substantially filled with a casting compound, in particular a grout, such that the foundation reinforcement is further stiffened and/or is capable of dissipating greater forces from the foundation pile into the seabed.
In order to enable quick and easy supply and filling in with a casting compound, in particular a grout, the sleeve, in particular at least one sleeve element, and/or the support, in particular a support element, can have at least one grout port, which may be connected to a grout line which preferably runs on the inside of the foundation pile, and supplies a casting compound, in particular a grout.
A first particularly preferred embodiment of the method provides that sides of the sleeve elements, collar elements and/or support elements that are adjacent to one another in the circumferential direction are connected to one another in a positive-locking, articulated and/or form-fitting manner, preferably by at least partial introduction into the seabed or before at least partial introduction into the seabed; in this way the respective reinforcement elements can be connected particularly expediently. The at least two adjacent sleeve elements of adjacent reinforcement elements can be positioned overlapping in portions in the circumferential direction, in particular to form a closed sleeve in the radial direction. This favours connection to the foundation pile and thus support of the foundation pile. If the sleeve, in particular the sleeve elements, is/are connected to the outside of the reinforcement portion of the foundation pile, which is spaced apart by a gap, via a casting compound, in particular grout, introduced into the gap, a durable connection can be achieved and large forces can be dissipated. Alternatively or additionally, adjacent sleeve elements can be arranged at a distance from one another in the region of at least one lead-through opening in the foundation pile. This ensures that submarine cables, for example, can be fed through into or out of the foundation pile easily and without damage. Irrespective of this, adjoining support elements of adjacent reinforcement elements can each be joined in a positive-locking manner, in particular via at least one hook portion and at least one engagement portion, in order to enable simple and moreover functional joining. The space between the collar and the foundation pile below the annular disc is preferably at least substantially filled with a casting compound, in particular a grout, in order to further stiffen the foundation reinforcement and/or to enable dissipation of greater forces from the foundation pile into the seabed. Alternatively or additionally, a casting compound, in particular a grout, can be supplied via a grout port in the sleeve, in particular in at least one sleeve element, and/or in the support, in particular in at least one support element. In this way, the corresponding free space can be filled in very easily, reliably and quickly. This is the case in particular when the casting compound, in particular the grout, is fed in via a grout line. The latter can run outside the foundation pile. However, it may be preferred for the grout line to run inside the foundation pile. This simplifies connecting the grout line and protects it from external damage. The invention is explained in more detail below on the basis of drawings depicting merely exemplary embodiments. In the drawing:
Fig. 1 shows an offshore wind turbine with a first monopile foundation according to the invention and a first monopile foundation installation according to the invention in schematic side view,
Fig. 2 shows a detail of the offshore wind power plant in the region of the monopile foundation installation in perspective view,
Fig. 3 shows a schematic representation of the method for producing the monopile foundation and the monopile foundation installation from Fig.1 in a schematic representation,
Fig. 4 shows a detail of the monopile foundation installation in plan view,
Fig. 5 shows the detail of the offshore wind power plant from Fig. 1 in horizontal sectional view, Figs. 6A-B show a detail of a second monopile foundation according to the invention and a second monopile foundation installation according to the invention in an assembled position and in a position during production, each in perspective view,
Fig. 7 shows a detail of a third monopile foundation according to the invention and a third monopile foundation installation according to the invention in perspective view,
Fig. 8 shows a detail of a fourth monopile foundation according to the invention and a fourth monopile foundation installation according to the invention in perspective view and
Fig. 9 shows a detail of a fifth monopile foundation according to the invention and a fifth monopile foundation installation according to the invention in a perspective view.
Fig. 1 shows an offshore wind power plant W that includes a monopile foundation installation 1 with a monopile foundation 2. The monopile foundation installation 1 comprises a foundation pile 3 and a foundation reinforcement 4. Both the foundation pile 3 and the foundation reinforcement 4 are partially embedded in the seabed M. The foundation pile 3 is formed by a steel tube which is open at the bottom and which extends upwards above sea level S. The illustrated and in this respect preferred foundation pile 3 comprises a foundation portion GA for introduction into the seabed and a reinforcement portion VA for reinforcing the foundation pile 3 with the foundation reinforcement 4. The tower structure T of the wind turbine W, which carries the nacelle G and the rotor R, is placed on the upper end of the foundation pile 3. The monopile foundation installation 1 is shown in detail in Fig. 2. The foundation reinforcement 4 is provided on the outside adjacent to the foundation pile 3 and circumferentially around the foundation pile 3. The foundation pile 3 is surrounded by a sleeve 5 of the foundation reinforcement, wherein, in the illustrated and in this respect preferred monopile foundation installation 1, the annular gap 6 between the sleeve 5 and the foundation pile 3 is filled with a casting compound 7, in particular in the form of a grout or special concrete, to ensure a flush and firm connection of the foundation reinforcement 4 to the foundation pile 3. The sleeve 5 is connected to the collar 9 of the foundation reinforcement 4 via a support 8. The support 8 is here formed by a row of support elements 10 emerging from the sleeve 5 and pointing radially outwards in a star shape, which engage with the collar 9 with their outer ends. In the case of the monopile foundation installation 1 shown and in this respect preferred, the collar 9 is designed as an at least substantially cylindrical steel casing, which has been driven into the seabed M with its lower end. For greater clarity, the seabed M has been omitted from Fig. 2. However, the collar 9 can be embedded into the seabed M at least substantially up to its upper edge. If necessary, the collar 9 can also protrude above the sea floor M with an upper portion. Forces that act laterally on the wind turbine W are partially dissipated directly via the foundation pile 3 into the seabed M and partially transmitted via the casting compound 7 or grout connection GV to the sleeve 5, from where the forces are then conducted radially outwards via the support elements 10 and dissipated into the surrounding collar 9. The collar 9 is supported on the seabed M and thus supports the entire wind turbine W, even if the foundation pile 3 cannot be driven that far into the seabed M. In such cases, or in cases where the foundation pile 3 loosens over time, the foundation reinforcement 4 is preferably used. The foundation reinforcement 4 is in fact constructed in two parts, such that the foundation reinforcement 4 can be subsequently installed on the foundation pile
3. Installation then proceeds as shown schematically in Fig. 3. For this purpose, the foundation reinforcement 4 shown and in this respect preferred is formed from two separate reinforcement elements 11, 12. A first reinforcement element 11 is first brought up to the foundation pile 3 with a sleeve element 13 and then introduced downwards into the seabed M. This is preferably done by a vibration method. If necessary, the reinforcement element 11 can be inserted so far into the seabed M that the associated collar element 14 is arranged in the seabed M at least substantially over its entire height. However, the support elements 10 are then preferably still arranged above the seabed
M. As the next step, the second reinforcement element 12 is brought up to the foundation pile 3 and then lowered. The second connecting element 12 is then driven at least substantially as far into the seabed M as the first reinforcement element 11. The lateral edges of the sleeve elements 13, 15 are designed in such a way that the edges overlap one another laterally and in this way form a circumferentially closed sleeve 5. The annular gap 6 between the sleeve 5 and the foundation pile 3 can be easily filled in with a casting compound 7. The casting compound 7 is preferably formed by a special concrete or a grout or another casting compound 7. Furthermore, the reinforcement elements 11, 12 are positively connected to one another via the support elements 10. For this purpose, in the foundation reinforcement 4 shown and in this respect preferred, of the adjacent support elements 10, one support element is in each case provided with a hook portion 16 and the other support element 10 is provided with an engagement portion 17, into which the corresponding hook portion 16 can engage in a positive-locking manner when the second element 12 is inserted into the seabed M in the correct orientation. Alternatively or additionally, the reinforcement elements could also be connected in an articulated manner via a pivot connection or a joint. This then in particular proceeds before the reinforcement elements are introduced into the seabed. In this way, a reinforcement element can first be placed laterally by the foundation pile. A further reinforcement element, which is connected in an articulated manner to the first reinforcement element, can then be pivoted about a pivot axis which extends at least substantially parallel to the longitudinal axis of the foundation pile. In this way, the foundation pile can, if necessary, be at least substantially completely circumferentially surrounded by at least two reinforcement elements. If the foundation pile is completely surrounded by at least two reinforcement elements, two reinforcement elements on adjacent sides, which are preferably not also connected by an articulated connection, can be force-fittingly and/or positively connected in order to close the foundation reinforcement all around. A connection comprising a hook element is particularly suitable as a force-fitting and/or positive-locking connection. However, this is not imperative.
Fig. 4 shows a detail of a connection region between the two reinforcement elements 11, 12 before the actual joining. The sleeve 5 of the reinforcement element 12 shown above has a lug 18 which overlaps the sleeve element 13 of the lower reinforcement element 11 on the outside. In addition, the support element 10 of the upper reinforcement element 12 has a hook portion 16, which partially extends around the support element 10 of the lower reinforcement element 11 in a positive-locking manner, specifically in the region of the engagement portion 17. The positive locking acts in the circumferential direction, in the radial direction and also downwards.
Fig. 5 shows the monopile foundation installation 1 from Fig. 1 in a horizontal sectional view from above. In the monopile foundation 2 shown and in this respect preferred, the two reinforcement elements 11, 12 of the foundation reinforcement 4 are each at least substantially semicircular and each at least substantially mirror-symmetrical. However, neither is not absolutely necessary. The two reinforcement elements 11,12 are connected to one another on the mutually adjoining sides via the positive-locking connections of the adjoining support elements 10, including the hook portions 16, which are described in detail in connection with Fig. 4. After installing the reinforcement elements 11, 12 in the seabed and after connecting the reinforcement elements 11, 12 to one another in the two connection regions, the annular gap 6 formed between the foundation pile 3 and the sleeve 5 formed from the two sleeve elements 13, 15 and the associated lugs 18 is filled in by a casting compound 7, in particular in the form of a grout, to form a grout connection GV. Figs. 6A-B show an alternative connection between two adjacent reinforcement elements 20, 21 of an alternative foundation reinforcement 22, once in the assembled state and once in the unassembled state. Here, two hook portions 24 are provided on a support element 23, each comprising a pin portion 25 pointing downwards, which engage in corresponding engagement portions 26 of the adjacent support element 27. The two hook portions 24 and the engagement portions 26 are provided at the opposite ends of the support elements 23, 27 in the radial direction. Adjacent to the inner ends of the respective support elements 23, 27 there is provided a sleeve 28 with sleeve elements 29, 30 overlapping in an edge region, wherein one sleeve element 29 is overlapped on the outside by the adjacent sleeve element 30 laterally in the circumferential direction by means of a corresponding lug 31.
Fig. 7 shows a monopile foundation installation 40 in which the foundation pile 41 has two lead-through openings 42 through which the power cable 43 enters and then exits from the foundation pile 41. To ensure that the power cable 43 is not damaged by the foundation reinforcement 44 in the region of the lead-through openings 42, the sleeve 45 is partially recessed in adjacent regions 46 in the region of the lead-through openings 42. Reinforcement elements 47, 48 here also abut in the regions of the lead-through openings
42. Above the lead-through openings 42, the adjoining sleeve elements 49, 50 overlap one another, specifically with the aid of appropriately designed lugs 51. The support elements 52, 53 in this connection region 54 are positively connected to one another via a type of bridge 55, which leaves sufficient space underneath for the power cable 43, such that the power cable 43 cannot be crushed when the foundation reinforcement 44 is installed.
Fig. 8 shows a monopile foundation installation 60 which in principle corresponds to the monopile foundation installation 2 of Fig. 2. However, in the foundation reinforcement 61 of Fig. 7, the gap 62 between the sleeve 63 and the collar 64 is at least substantially closed by an annular disc 65, which extends at least substantially radially outward, is formed in two parts from annular disc elements 65a and is provided in addition to the support elements 10. In this way, seabed cannot be washed out of the region between the foundation pile 3 and the collar 64. In addition, with the foundation reinforcement 61 shown, a line 67 for supplying casting compound 7 or grout can be connected to a port 66 on the annular disc 65. As a result, the space below the annular disc 65, between the foundation pile 3 and the collar 64 and above the seabed M can be filled with the appropriate casting compound 7, if required.
In the monopile foundation installation 70 shown in Fig. 9, two ports 71, 72 are provided in the foundation pile 74, each for a line 73 carrying a casting compound 7. One port 71 is provided at the level of the sleeve 75 and one port 72 at the level of the collar 76. The upper port 71 serves to fill in the annular gap 79 between the foundation pile 3 and the sleeve 75 with casting compound 7, while the lower port 72 serves to fill in the free space 77 below the annular disc 78 with casting compound 7. If necessary, one port 71, 72 can also be dispensed with, specifically in the event that the free space 77 and the annular gap 79 are not to be filled in, or in the event that the free space 77 and the annular gap 79 together consist of a line 73 and are to be filled in via a common port 71, 72. List of reference signs 1 Monopile foundation installation 2 Monopile foundation 3 Foundation pile 4 Foundation reinforcement Sleeve 6 Annular gap 7 Casting compound 8 Support 9 Collar Support element 11,12 Reinforcement element 13 Sleeve element 14 Collar element Sleeve element 16 Hook portion
17 Engagement portion 18 Lug 20, 21 Reinforcement element 22 Foundation reinforcement 23 Support element 24 Hook portion Pin portion 26 Engagement portion 27 Support element 29, 30 Sleeve element 31 Lug Monopile foundation installation 41 Foundation pile 42 Lead-through opening 43 Power cable 44 Foundation reinforcement Sleeve 46 Region 47, 48 Reinforcement element 49, 50 Sleeve element 51 Lug 52, 53 Support element 54 Connection region Bridge 60 Monopile foundation installation 61 Foundation reinforcement 62 Gap 63 Sleeve 64 Collar 65 Annular disc 65a Annular disc element 66 Port 67 Line 70 Monopile foundation installation 71,72 Port
73 Line 74 Foundation pile 75 Sleeve 76 Collar 77 Free space 78 Annular disc 79 Annular gap G Nacelle GA Foundation portion GV Grout connection M Seabed R Rotor S Sea level T Tower structure VA Reinforcement portion W Wind turbine