EP3207186B1 - Off shore foundation - Google Patents

Description

The present invention relates to a foundation system for the foundation of an offshore structure. The invention also relates to a method for the foundation of an offshore structure and an offshore structure with a corresponding foundation system.

Offshore structures in the context of the present invention are, for example, substations, wind turbines or drilling or production platforms.

For certain types of foundations for offshore structures, especially for offshore wind turbines, a pile foundation in the sea bed is required. Common foundation types are, for example, so-called monopiles, jackets, tripods or tripiles. For example, jackets are triangular or square half-timbered structures made of steel tubes, the upper end of which protrudes from the sea after installation. For example, a conventional wind turbine, a transformer platform or a drilling platform can be built on a jacket.

In the case of a jacket foundation, when the piles are set, they must be positioned at a specified distance on the sea bed during the so-called "prepiling", which is ensured using appropriate templates. This presupposes that the subsoil quality is such that all piles to be set can be driven up to a given load-bearing horizon of the sea bed. There are no possibilities of variation with regard to the distance or the location for setting the piles.

In the case of a jacket foundation, a steel lattice structure / steel tube structure is then placed on the steel piles, which receives a so-called "transition piece" above sea level. The transition piece then takes up the actual structure, for example in the form of a substation.

In this respect, monopiles are preferably used when founding wind turbines in water depths of up to 35 m, since this type of foundation is less expensive. Usually at least one substation is assigned to the wind power plant and positioned in the immediate vicinity of the wind power plant. In the substation, the voltage generated by the wind turbine can be transformed from, for example, 33kV to 155kV and rectified in order to be able to transmit it over long distances with low loss by means of high-voltage direct current (HVDC) transmissions.

It is also desirable to use monopiles for the foundation of substations, since their installation, as already described above, is much easier than, for example, the installation of a jacket. Due to the large extent and above all due to the large mass of a substation of up to more than 1000 tons, this represents a large oscillating mass when it is founded on a monopile. Due to the impact of wind on the transformer station and due to the impact of wind and waves on the monopile, the entire Structure stimulated to vibrations, which on the one hand have a negative impact on the structural integrity of the monopile and the substation and can also cause nausea in the personnel on the substation.

The EP 2 742 170 A1 describes a platform structure with a platform and a floating structure or buoyancy structure. The platform is connected to the seabed by means of tension cables.

The DE 20 2007 009 474 U1 describes an offshore platform with several foundation piles, a transition piece and a building connection structure formed on the transition piece.

The KR 101 046 648 B describes a monopile structure equipped with a wind power generator and a maintenance platform. Guy lines are attached directly to the monopile to secure the structure.

The present invention is therefore based on the object of providing a foundation system for offshore structures, by means of which offshore structures can be founded cheaply and quickly, and which also have a high degree of stability, so that the offshore structures established by means of the foundation system according to the invention have smaller oscillation amplitudes. Furthermore, the present invention is based on the objects of providing a cost-effective, quick-to-erect and stable offshore structure and a method for erecting such an offshore structure.

According to the invention, these objects are achieved by a foundation system with the features of claim 1, by an offshore structure with the features of claim 9 and by a method for the foundation of an offshore structure with the features of claim 10.

More precisely, the foundation system according to the invention for the foundation of an offshore structure comprises a monopile with an anchoring section which can be anchored in the seabed and a connecting section arranged at the opposite end. The foundation system further comprises a platform structure that can be directly connected to the connecting section of the monopile or indirectly connected via a transition piece and arranged above the water surface. The foundation system according to the invention is characterized in that the stabilization devices can each be connected directly to the platform structure or indirectly via the transition piece with the platform structure and can be brought into contact with the seabed, so that tensile and / or compressive forces between the seabed and the platform structure by means of the stabilization devices are transferable. In this case, fastening points of the stabilization devices on the platform structure or on the transition piece together with the connecting section of the monopile in the assembled state of the foundation system span a plane with a horizontal extension component and the stabilization devices run perpendicularly from the platform structure and / or the transition piece towards the seabed.

The stabilization devices can be arranged symmetrically to the monopile or asymmetrically to the monopile. Furthermore, the monopile can be arranged centrically or eccentrically with respect to the stabilizing devices.

Furthermore, it is also possible that the foundation system comprises at least three stabilization devices which can each be connected directly to the platform structure or indirectly via the transition piece to the platform structure and can be brought into contact with the seabed. The fastening points of the stabilization devices on the platform structure or on the transition piece then span a plane in the assembled state of the foundation system which has a horizontal extension component.

Since the fastening points span a horizontal plane or the plane spanned by the fastening points has a horizontal extension component, horizontal swaying movements of the platform structure, which are caused by horizontal forces (wind and waves), can be counteracted and reduced in size by means of the stabilization devices. Furthermore, by providing the stabilization devices, the natural angular frequency of the offshore structure established by means of the foundation system according to the invention is increased in a range that lies outside the usual wave frequency spectrum, so that a resonant rocking of the offshore structure due to wind and / or waves is avoided. Furthermore, by providing the stabilization devices, it is achieved that even larger offshore structures can be founded on monopiles without having to accept a lower stability of the offshore structure. It can therefore be avoided that a jacket has to be used for the foundation of the offshore structure in order to achieve the desired stability. The foundation of an offshore structure with the aid of a monopile is significantly easier, less time-consuming and more cost-effective than the foundation of an offshore structure with a jacket.

Since the fastening points of the stabilization devices on the platform structure or on the transition piece span a plane with a horizontal extension component, this spanned plane has a normal component which runs parallel to the monopile.

Furthermore, the mutual spacing of the fastening points from one another is preferably greater than the cross-sectional extent of the monopile. As a result, increased stabilizing forces can be transmitted to the platform structure by the stabilizing devices. The same applies to an indirect connection between the stabilization devices and the platform structure. The stabilization devices can be connected indirectly to the platform structure via a transition piece, that is to say via a coupling device.

If the foundation system comprises three stabilization devices, then the stabilization devices, and more precisely the attachment points of the stabilization devices on the platform structure and / or on the transition piece, are arranged at three corner points of a triangle in a plan view of the foundation system. With four stabilization devices, the contact points of the stabilization devices can be seen in a plan view of the foundation system the platform structure and / or be arranged on the transition piece at corner points of a rectangle or a square or generally a square polygon.

Only through the feature that the contact points of the stabilization devices with the platform structure and / or with the transition piece span a plane with a horizontal extension component can any oriented horizontal forces be absorbed by means of the stabilization devices, so that excessive movement of the offshore structure is prevented by means of the stabilization devices becomes.

The stabilization devices run perpendicularly from the platform structure and / or from the transition piece in the direction of the sea floor. Due to the vertical extension of the stabilization devices, forces exerted on the offshore structure by means of wind and / or waves can be absorbed particularly effectively by the stabilization devices.

The stabilizing devices are preferably each designed as stabilizing supports which are slidably connected to the platform structure and / or to the transition piece and can be lowered from the platform structure and / or the transition piece onto the seabed. The stabilizing supports can be locked to the platform structure and / or to the transition piece, so that axially extending compressive forces and transverse forces can be transmitted to the seabed via the respective stabilizing supports.

A corresponding design of the foundation system offers the advantage that no anchoring of the stabilization devices in the seabed or in the seabed is absolutely necessary in order to counteract fluctuations in the offshore structure. The assembly of the offshore structure is very simple, because the offshore structure only has to be placed on the monopile or on a platform held by the monopile and connected to it, whereupon the stabilizing supports stored in guide sleeves, for example, are placed on the seabed be lowered in order to be locked after contact with the seabed with the platform structure and / or with the transition piece.

Preferably, the stabilization devices can each be connected to the seabed, so that tensile forces and compressive forces can be transmitted between the seabed and the platform structure via the respective stabilization devices.

The respective connections can be implemented using anchors, for example. A corresponding design of the foundation system increases the stability of the offshore structure again, since a swaying movement can be compensated for by a stabilization device loaded with pressure and a stabilization device arranged opposite it and loaded with tension.

The stabilization devices are preferably each designed as flexible tension elements that can each be connected to the seabed.

A tension element can be an anchor hawser, an anchor chain or an anchor cable or a very generally flexible tension element. A design of the stabilization devices as tension elements offers the advantage that the platform structure and / or the coupling piece carrying it can be designed in a structurally simple manner, since no stabilizing supports have to be connected to the platform structure and / or to the transition piece in a displaceable manner.

For example, the tension elements can be wound onto a roll before being fixed in the seabed, so that after connecting the offshore structure to the monopile or the platform structure, the tension elements are unwound from the rolls until they are in contact with the seabed, whereupon the tension elements connected to the seabed in a suitable manner.

Preferably, the foundation system comprises a number of foundation piles corresponding to the number of tension elements, each with one The drop anchors connected to the tension elements and each include a potting compound column which is cast in situ within the seabed and extends over a length within the seabed.

By means of a drop anchor and at least one tension element connected to the drop anchor, an anchor point at which the tension element is attached can be set in the sea bed.

The drop anchor is dimensioned, for example, with regard to its mass and with regard to its geometry, so that it penetrates the sea bed to a predetermined depth due to its kinetic energy in free fall. This takes the anchor cable attached to it or the tension element attached to it with it. One or more casting compound lines, which are also taken along by the drop anchor, can be attached to the tension element. Through this casting compound line, a hardenable casting compound, for example a concrete hardenable under water, is then pressed into the firing channel under pressure, the tension elements at the same time serving to reinforce the casting compound column thus produced in situ.

As a drop anchor in the sense of the present invention, a so-called torpedopile is provided, for example, which has a torpedo-shaped base body with a penetrating tip and which is provided at the end with several torpedo wings for the purpose of stabilization. The torpedo body can, for example, be made hollow and comprise one or more ballast chambers that can be filled with ballast.

Appropriate design of the foundation system has the advantage that the structure to be erected can be braced on one or more tension elements, which naturally leaves a certain amount of space when placing the offshore structure, so that the foundation piles are not set using a template or the underwater structure of the building is specified.

In addition, if the foundation system is designed accordingly, there is no need to set piles using ramming devices. The process of setting the torpedo / drop anchor is unique, whereas the ramming of piles is associated with a recurring sound input into the marine environment. Several tension elements can of course also be attached to a drop anchor, although one tension element is referred to in the following.

As already mentioned above, within the meaning of the present invention, a tension element is a flexible tension element which can only transmit tensile forces, but not compressive forces.

The drop anchor is preferably designed as a stimulable drop anchor, the drop anchor in an excited state liquefying the sea floor in a vicinity of the drop anchor, so that penetration of the drop anchor into the sea floor is supported. An excited state of the drop anchor can in particular be a state in which the drop anchor vibrates so that the sea floor in the vicinity of the drop anchor is liquefied. The anchor vibrations can be generated when the anchor is dropped or when it hits the seabed by an internal, appropriately mounted unbalanced mass, which is fixed with an internal suspension within the drop anchor in such a way that the internal oscillation frequency corresponds to the excitation frequency of the bottom, typically in the range of 15-45Hz .

The foundation pile preferably comprises protective piping which extends over part of the length of the potting compound column.

Furthermore, the foundation pile preferably comprises a sheet pile wall which extends over part of the length of the potting compound column.

In an advantageous embodiment, the foundation system comprises a tensioning device, by means of which the tension elements connected to the seabed can be acted upon by force. With an appropriate design of the foundation system, an even greater stability of the offshore structure can be achieved.

The platform structure is preferably designed as a transformer station and / or the transformer station comprises the platform structure.

The object on which the invention is based is also achieved by an offshore structure comprising a foundation system as described above, the offshore structure being positioned on and connected to the monopile of the foundation system, the stabilization devices being in contact with the seabed.

All advantageous designs that are described in connection with the foundation system can of course also be advantageous designs of the offshore structure.

• Bereitstellen eines Monopiles mit einem im Meeresboden verankerbaren Verankerungsabschnitt und einem am gegenüberliegenden Ende angeordneten Verbindungsabschnitt;
• Bereitstellen einer mit dem Verbindungsabschnitt des Monopiles direkt verbindbaren oder über ein Übergangsstück mittelbar verbindbaren und oberhalb der Wasseroberfläche anordenbaren Plattformstruktur;
  • Verankern eines Verankerungsabschnitts eines Monopiles im Meeresboden;
  • Anordnen und Verbinden des Offshore-Bauwerkes auf der Plattformstruktur;
• Bereitstellen von zumindest zwei Stabilisierungseinrichtungen, die jeweils direkt mit der Plattformstruktur oder mittelbar über das Übergangsstück mit der Plattformstruktur verbindbar und mit dem Meeresboden in Kontakt bringbar sind, so dass Zug und / oder Druckkräfte zwischen dem Meeresboden und der Plattformstruktur übertragbar sind, wobei Befestigungspunkte der Stabilisierungseinrichtungen an der Plattformstruktur oder an dem Übergangsstück in Richtung Meeresboden verlaufen; und in Kontakt bringen der Stabilisierungseinrichtungen mit dem Meeresboden.
  • In Kontakt bringen der Stabilisierungseinrichtungen mit dem Meeresboden. Vorteilhafterweise kann das Verfahren zur Gründung eines Offshore-Bauwerkes unter Verwendung eines Gründungssystems, das eine der Anzahl der Zugelemente entsprechende Anzahl von Gründungspfählen umfasst, die jeweils einen mit einem der Zugelemente verbundenen Fallanker und jeweils ein in situ innerhalb des Meeresbodens vergossene und sich innerhalb des Meeresbodens über eine Länge erstreckende Vergussmassesäule umfassen, folgende weitere Verfahrensschritte aufweisen:
    • Bereitstellen und Anordnen eines Fallankers in einer vorbestimmten Höhe oberhalb des Meeresbodens;
    • Befestigen eines Zugelements an dem Fallanker;
    • Befestigen einer Vergussmasseleitung an dem Zugelement;
    • Abwerfen des Fallankers, so dass dieser in den Meeresboden eindringt; und
    • Einbringen einer aushärtbaren Vergussmasse in den vom Fallanker beim Eindringen in den Meeresboden erzeugten Schusskanal.

Furthermore, the object on which the invention is based is achieved by a method for the foundation of an offshore structure, the method comprising the following method steps:

• Providing a monopile with an anchoring section which can be anchored in the seabed and a connecting section arranged at the opposite end;
• Providing a platform structure which can be directly connected to the connecting section of the monopile or can be connected indirectly via a transition piece and can be arranged above the water surface;
  • Anchoring an anchoring portion of a monopile in the sea floor;
  • Arranging and connecting the offshore structure on the platform structure;
• Provision of at least two stabilization devices, each of which can be connected directly to the platform structure or indirectly via the transition piece with the platform structure and can be brought into contact with the seabed, so that tensile and / or compressive forces can be transmitted between the seabed and the platform structure, with attachment points of the stabilization devices run on the platform structure or on the transition piece in the direction of the sea floor; and bringing the stabilizers into contact with the seabed.
  • Bring the stabilizers into contact with the seabed. Advantageously, the method for the foundation of an offshore structure using a foundation system comprising a number of foundation piles corresponding to the number of tension elements, one drop anchor connected to one of the tension elements and one cast in situ within the seabed and located within the seabed above comprise a length-extending potting compound column, have the following further method steps:
    • Providing and arranging a drop anchor at a predetermined height above the sea floor;
    • Attaching a tension member to the drop anchor;
    • Attaching a potting compound line to the tension element;
    • Dropping the drop anchor so that it penetrates the seabed; and
    • Introducing a hardenable potting compound into the firing channel created by the drop anchor when it penetrates the seabed.

The displacement channel generated by the drop anchor when it dips into the sediment of the sea bed / sea floor is referred to as a shot anchor in the sense of the present invention.

The method has the particular advantage over conventional pile foundations that the structure to be erected can be braced on one or more tension elements, which naturally leaves a certain amount of free space in the placement of the offshore structure so that the foundation piles cannot be set using a template or the underwater structure of the building is specified.

In an advantageous variant of the method according to the present invention it is provided that the potting compound is introduced into the firing channel over at least part of the length of the tension element, the tension element remaining in the hardened potting compound. The tension element serves, on the one hand, to reinforce the casting compound and, on the other hand, to brace the offshore structure to be erected. The depth to be reached by the drop anchor is reduced, since the skin friction required to brace the main structure on the tension element is reduced and is supplied by the potting compound body.

The drop anchor is expediently provided with ballast before it is dropped, the ballast mass being selected so that the drop anchor penetrates the sea bed up to a stable floor horizon.

In a particularly advantageous variant of the method, it is provided that the drop anchor is suspended from a release line and the release takes place by actuating a release mechanism on the release line. The drop anchor is in this case attached to both the discharge line and one or more pulling elements.

In the method, the drop anchor can preferably be introduced into the sea bed through a protective pipe or a sheet pile wall, the protective pipe or the sheet pile wall being set beforehand. In order to facilitate penetration of the drop anchor into the sea bed, it can be provided that the sea bed below the protective pipe or inside the sheet pile wall is fluidized by injecting compressed air or water before the drop anchor is dropped.

Alternatively, for example, when using a protective tube, it can be provided that the protective tube is pumped empty before the drop anchor is dropped so that the kinetic energy with which the drop anchor can penetrate the seabed is significantly increased.

Alternatively, the protective tube, which can extend beyond the seabed, for example, can be pumped full of liquid, so that an increased hydrostatic pressure is built up at the foot of the tube through the liquid column, which facilitates the penetration of the drop anchor into the seabed. The liquid column can be adjusted accordingly with regard to its specific weight, for example. For example, a barite solution can be used as the liquid.

Figur 1:

eine schematische Darstellung eines mittels des erfindungsgemäßen Gründungssystems gegründeten Offshore-Bauwerkes; und

Figur 2:

Ein Offshore-Bauwerk, das mittels eines Gründungssystems gemäß einer alternativen Ausführungsform der vorliegenden Erfindung begründet ist.

Further advantages, details and features of the invention emerge from the exemplary embodiments explained below. The following show in detail:

Figure 1:

a schematic representation of an offshore structure established by means of the foundation system according to the invention; and

Figure 2:

An offshore structure founded by means of a foundation system according to an alternative embodiment of the present invention.

In the description that follows, the same reference symbols denote the same components or the same features, so that a description made with reference to a figure with regard to a component also applies to the other figures, so that a repeated description is avoided.

In Figure 1 an offshore structure 1 is shown, which is founded on the sea floor U by means of a foundation system according to the invention.

Out Figure 1 it can be seen that the foundation system has a monopile 10 with an anchoring section 11 that can be anchored in the seabed U and a connecting section 12 opposite the anchoring section 11. The anchoring section 11 is set into the sea bed U, for example, by ramming or flushing. The foundation system according to the invention further comprises a platform structure 3 that can be connected to the connecting section 12 of the monopile 10. In the exemplary embodiment shown, the platform structure 3 is connected directly to the monopile 10. However, it is also possible for the platform structure 3 to be connected to a transition piece arranged between the monopile 10 and the platform structure 3. A corresponding transition piece is not shown in the figures.

Out Figure 1 it can also be seen that a connecting structure 2 in the form of a substation 2 is placed on the platform structure 3. The substation 3 comprises a large number of individual components, which can easily increase the weight of the substation to over 1000 tons.

However, the present invention is not restricted to the connection structure 2 being designed in the form of a substation 2. Thus, according to the invention, the connection structure 2 can also be designed as a wind power plant or also as a drilling or conveying platform.

The foundation system according to the invention comprises at least two stabilization devices 20. In the case of the in Figure 1 The illustrated embodiment, the stabilizing devices 20 are designed as support feet or as stabilization supports 21. The stabilizing supports 21 are each directly with the platform structure 3 connected and lowered to the sea floor U. At the in Figure 1 The installation shown, the stabilizing supports 21 are already deposited on the sea bed U. The installation can take place in such a way that the platform structure 3 is placed on the connecting section 12 of the monopile 10, in which case the stabilizing supports 21 in guide sleeves of the platform structure 3 are in an upper position so that they do not move downwards towards the seabed U protrude down. After the platform structure 3 has been connected to the monopile 10, the stabilizing supports 21 are lowered onto the sea bed U so that they are in contact with the sea bed U. The stabilizing supports 21 are then locked to the platform structure 3, so that axially extending thrust forces can be transmitted to the seabed U via the respective stabilizing supports 21.

Since the guide sleeves on the platform structure 3 are spaced apart from one another in such a way that they span a plane with a horizontal extension component, in the present example a horizontal plane, and the stabilizing supports 21 are arranged at the four corner points of the platform structure 3, horizontal forces that act on act on the monopile 10 or on the substation 2, are absorbed by the stabilizing supports 21. This horizontal force action can be caused, for example, by wind which acts on the monopile 10 and on the substation 2. Furthermore, horizontal forces are transmitted to the monopile 10 by waves or the impact of a ship.

Swinging movements of the offshore structure 1 thus established is consequently reliably counteracted by the stabilizing supports 21. The stabilizing supports 21 also have the effect that the oscillation frequency of the offshore structure changes in such a way that it lies outside the usual wave frequency spectrum. The resonance frequency of the offshore structure 1 established by means of the foundation system according to the invention is above 0.25 Hz and usually also above 0.3 Hz.

In the exemplary embodiment shown, the stabilizing supports 21 are not connected to the sea floor U or are not anchored in it.

However, it is also possible that the stabilization supports 21 are connected to the seabed U, in particular anchored, so that not only compressive forces but also tensile forces can be transmitted between the seabed U and the platform structure 3 via the stabilization supports 21. A corresponding design of the foundation system increases the stability again, since when a force is applied, one stabilizing support 21 can absorb compressive forces and another stabilizing support 21 opposite this stabilizing support 21 can absorb tensile forces.

In Figure 2 an offshore structure 1 is shown that is founded on the sea bed U by means of a foundation system according to a further embodiment of the present invention. The stabilization devices 20 are designed as flexible tension elements 22 which can be connected to the seabed U. Tension elements 22 within the meaning of the present invention are anchor cables 22, anchor cables 22, anchor chains 22 or, in general, flexible tension elements 22. Flexible tension elements 22 within the meaning of the present invention are tension elements via which tensile forces, but not shear forces, can be transmitted.

The in Figure 2 The illustrated embodiment, four tension elements 22 are provided at four corners of the platform structure 3, which are each connected to the sea floor U.

In the exemplary embodiment shown, the foundation system also comprises four drop anchors 31 in the form of four torpedopiles 31, which are each connected to a tension element 22. The drop anchors 31 are part of foundation piles 30 which, in addition to the drop anchors 31, comprise casting compound columns 32.

The installation of the foundation system is such that after connecting the platform structure 3 to the connecting section 12 of the monopile 10, the respective drop anchors 31 with tension elements 22 connected to them are dropped from a predetermined height into the seabed U, so that the drop anchors 31 form a firing channel. A hardenable potting compound is then introduced into this firing channel, which encapsulates the in Figure 2 Form potting compound columns 32 shown.

Consequently, only tensile forces can be transmitted via the tension elements 22, with horizontal forces from any direction being able to be compensated due to the arrangement of the attachment points of the tension elements 22 on the platform structure 3, since the attachment points of the tension elements 22 on the platform structure 3 span a plane with a horizontal extension component.

Preferably, the foundation system further comprises an in Figure 2 Tensioning device, not shown, by means of which the tension elements 22 can be tensioned, as a result of which the stability of the offshore structure 1 established by means of the foundation system is increased again.

List of reference symbols:

1

Offshore structure

2

topside / connection structure / substation

3

Platform structure / platform

10

Monopile

11

Anchoring section (of the monopile)

12th

Connecting section (of the monopile)

20th

Stabilizing device

21

Stabilizing support / stabilizing device

22nd

Tension element / anchor rope / anchor chain / anchor cable / stabilization device

30th

Foundation pile

31

Drop anchor / torpedopile

32

Potting compound column

M.

Sea level / sea surface

U

Sea floor / subsoil

Claims (11)

1. Foundation system for the foundation of an offshore construction (1), comprising:

   - a monopile (10) having an anchoring portion (11) which can be anchored in the seabed (M) and comprising a connecting portion (12) arranged at the opposite end;

   - a platform structure (3) which can be connected to the connecting portion (12) of the monopile (10) directly or indirectly via a transition piece and can be arranged above the water surface; and

   - at least two stabilization devices (20, 21, 22), characterized in that the stabilization devices can each be connected directly to the platform structure (3) or indirectly to the platform structure (3) via the transition piece and can be brought into contact with the seabed (M), so that tensile and/or compressive forces can be transmitted between the seabed (M) and the platform structure (3); wherein, in the installed state of the foundation system, fastening points of the stabilization devices (20, 21, 22) on the platform structure (3) or on the transition piece, together with the connecting portion (12) of the monopile (10), span a plane having a horizontal extension component; and the stabilization devices (20, 21, 22) extend perpendicularly from the platform structure (3) and/or from the transition piece in the direction of the seabed and are in contact with the seabed.
2. Foundation system according to claim 1, characterized by the following features:

   - the stabilization devices (20, 21, 22) are each designed as stabilization supports (21) which are movably connected to the platform structure (3) and/or to the transition piece and can be lowered from the platform structure (3) and/or the transition piece to the seabed (M); and

   - the stabilization supports (21) can be locked to the platform structure (3) and/or to the transition piece, so that axially extending compressive forces and transverse forces can be transmitted to the seabed (M) via the respective stabilization supports (21).
3. Foundation system according to either of the preceding claims, characterized in that the stabilization devices (20, 21, 22) can each be connected to the seabed (M) so that tensile forces can be transmitted via the respective stabilization devices (20, 21, 22).
4. Foundation system according to claim 1, characterized in that the stabilization devices (20, 21, 22) are each designed as a flexible tensile element (22) which can be connected to the seabed (M).
5. Foundation system according to claim 4, characterized in that the foundation system comprises a number of foundation piles (30) that corresponds to the number of tensile elements (22), which foundation piles each comprise a drop anchor (31) connected to one of the tensile elements (22) and each comprise a casting compound column (32) which is cast in situ in the seabed (M) and extends within the seabed (M) over a length.
6. Foundation system according to claim 5, characterized in that the drop anchor (31) is designed as a stimulable drop anchor (31), wherein, in a stimulated state, the drop anchor (31) liquefies the seabed (M) in a vicinity of the drop anchor (31) so that penetration of the drop anchor (31) into the seabed (M) is facilitated.
7. Foundation system according to any of claims 4 to 6, characterized in that the foundation system comprises a tensioning device by means of which the tensile elements (22) connected to the seabed (M) can be subjected to force.
8. Foundation system according to any of the preceding claims, characterized in that the platform structure (3) is designed as a transformer device (3) and/or the transformer device (2) comprises the platform structure (3).
9. Offshore construction (1), comprising a foundation system according to any of the preceding claims, characterized in that the offshore construction (1) is positioned on the monopile (10) of the foundation system and connected thereto.
10. Method for the foundation of an offshore construction (1), comprising the following method steps:

    - providing a monopile (10) having an anchoring portion (11) which can be anchored in the seabed (M) and comprising a connecting portion (12) arranged at the opposite end;

    - providing a platform structure (3) which can be connected to the connecting portion (12) of the monopile (10) directly or indirectly via a transition piece and can be arranged above the water surface;

    - anchoring an anchoring portion (11) of a monopile (10) in the seabed (M);

    - arranging the offshore construction (1) on the platform structure (3);

    - providing at least two stabilization devices (20, 21, 22) which can each be connected directly to the platform structure (3) or indirectly to the platform structure (3) via the transition piece and can be brought into contact with the seabed (M), so that tensile and/or compressive forces can be transmitted between the seabed (M) and the platform structure (3), wherein, in the installed state of the foundation system, fastening points of the stabilization devices (20, 21, 22) on the platform structure (3) or on the transition piece, together with the connecting portion (12) of the monopile (10), span a plane having a horizontal extension component, wherein the stabilization devices (20, 21, 22) extend perpendicularly from the platform structure (3) and/or from the transition piece in the direction of the seabed; and

    - bringing the stabilization devices (20, 21, 22) into contact with the seabed (M).
11. Method according to claim 10 using a foundation system having the features of claim 5, characterized by the further method steps:

    - providing and arranging a drop anchor (31) at a predetermined height above the seabed;

    - fastening a tensile element (22) to the drop anchor (31);

    - fastening a casting compound line to the tensile element (22);

    - dropping the drop anchor (31) so that it penetrates the seabed (M); and

    - introducing a curable casting compound into the injection channel created by the drop anchor (31) when penetrating the seabed (M).

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