EP2674532B1 - Method and system for providing a foundation for an offshore structure - Google Patents

Description

The invention relates to a method and a system for the foundation of an offshore structure to be erected with a building section at a predetermined installation height above the water surface or the prevailing sea level there. The foundation system according to the invention can be in particular a gravity-foundation system.

For the purposes of this invention, offshore structures are to be understood as meaning all buildings which are erected or erected in the sea and there in a zone with permanently present seawater. In that regard, the term "offshore" chosen here is not to be construed in accordance with the strict sovereign interpretation with reference only to those areas which are outside the coastal waters area belonging to the riparian state. Rather, offshore structures according to this invention explicitly include such structures that are within the territorial waters of the coastal state belonging to the riparian state.

Typical such offshore structures, which have been known for a long time and are being built both inside and outside the sovereign coastal waters of the riparian states, are drilling and working platforms of the oil and gas industry. Recently, plants for the generation, processing and distribution of wind energy, which are built at sea, are gaining significantly Importance. In large wind farms erected at sea, such as the alpha ventus park built in the North Sea, this is not just a matter of wind turbines. Rather, other interconnected with the individual wind turbines components are housed in offshore structures, eg converter systems in corresponding converter platforms. Also, there are pure residential and recreational platforms built at sea, which for example serve to accommodate service and maintenance technicians in the immediate vicinity of maritime facilities, such as wind turbines, during the work process.

All these applications and offshore structures have in common that they must be connected via a so-called foundation to the seabed and fixed there must be immovable or anchored. This definition is done, as already mentioned, via a so-called foundation. Such a foundation can basically be done in two different ways. So there are foundations, in which elements, such as piles driven into the seabed, so as to create a firm and static connection to the seabed, giving the building a founding foundation.

Alternatively foundations are known that work with the mere weight of a heavy foundation element, so-called gravity foundations, without in this case an additional connection to the seabed by driving in foundation constituents (for example, piles) consult.

The offshore structures to be built at sea often have to be erected with certain building sections above a minimum height at a predetermined building height. This applies, for example, to areas with residential containers set up therein (residential platforms), areas with sensitive technology (in particular electronics and electrics) and the like. The distance to the water surface is determined in particular by fluctuations in the sea level due to Tiedebewegungen and expected maximum wave heights, as they in strong winds or storms or because of other natural events are to be expected. In the case of such a high swell technically sensitive equipment and thus a supporting this building section or should Residential container with possibly still accommodated persons or work platforms are not to be washed over.

Naturally, building at sea is much more complicated than building a structure on land. Already the transfer of the corresponding building materials to the construction site is usually more complex and also more expensive than on land. In addition, a construction in situ, ie at the construction site, only conditionally, unlike on land, where buildings are to be built directly on site and place from there assembled building material. Thus, for example, it is very expensive to cast concrete parts from not yet hardened concrete on the high seas or to build them in any other way, especially if these parts are to be installed below the water surface. With appropriate effort, it is therefore connected to establish the connection of the building to the seabed, the founding.

Another considerable expense arises when building sections are to be connected to the foundation and mounted at a predetermined height. If, for example, a converter platform for a wind farm is erected, a connection to the seabed via the so-called foundation must first be made, then supports or stilts or columns are to be provided up to a height corresponding to the height of erection of the converter platform and the converter platform is at the ends provided for this purpose put on the supports or pillars.

Also, the inverter platform itself is typically not created in the harsh environment at sea. Rather, it is completed on land and shipped as a finished component or as a finished structure section to the site. This is typically done by ship freight with so-called transport barges. If such a converter platform is then applied to already projecting in height, ending in the construction height columns or columns, so either a correspondingly high transport barge must be provided with the problem of a high center of gravity and a risk of tipping and the problem of costly construction of a corresponding barge , or but it must be provided at sea, a corresponding crane that can lift the tons of heavy load of such a building section and spend in the relatively large building height. Although such cranes exist as ship cranes, but are available only in extremely small numbers and therefore expensive in use and associated with the use of very long waiting times, resulting in further costs in the overall project of construction of an offshore construction by appropriate delay.

Examples of how the prior art foundations for offshore structures are to be installed are with respect to offshore wind turbines in the DE 20 2010 010 094 U1 as well as in the DE 10 2007 002 314 A1 disclosed. The already very old proposals on platforms for the oil and gas industry according to the DE 24 42 186 such as DE 27 22 747 indicate founding possibilities in which the platforms can be raised up to the height of erection after appropriate foundations or supports.

While this has not yet been discussed in the old systems from the last two mentioned German pamphlets, recent maritime regulations and environmental requirements call for the possibility of a complete dismantling of an offshore structure, including the founding and "restoration" of the seabed, and even after that many decades of the existence of the offshore construction.

Against the background of these boundary conditions described above, the inventors have set itself the task of specifying a method and a system for the establishment of an offshore structure, which is to be erected with a building section at a predetermined installation height above the water surface, and the process and the system be designed such that in particular a Spend of the building height to be built in the building height up to the installation height with relatively simple and inexpensive means is possible without requiring special cranes or special transport barges are required with high structures, and the Connection of the building height to be arranged in the building section to the foundation can be done with relatively simple means.

In other aspects, the method and the foundation system should be advantageously designed so that a complete dismantling of the foundation is possible and this even after a very long use of the offshore construction site.

This object is achieved according to the invention and with regard to the method by such a method with the features of claim 1. Advantageous developments of such a method are specified in the dependent claims 2 to 8. An inventive foundation system, which solves the above-described object, is one having the features of claim 9. Advantageous developments of this foundation system are referred to in the dependent claims 10 to 18.

• Absenken eines Sockelelementes, welches mindestens ein fest mit letzterem verbundenes Vertikalrohr aufweist, wobei dieses Vertikalrohr in seinem Inneren ein relativ zu diesem in seiner Längsrichtung verlagerbares Säulenelement aufweist. Dieses Absenken erfolgt im Seewasser bis auf den Meeresgrund und zwar so, dass ein oberes, offenes Ende des Vertikalrohres oberhalb der Wasseroberfläche, jedoch unterhalb der Errichtungshöhe liegt.
• Absetzen des in der vorbestimmten Errichtungshöhe zu errichtenden Bauwerkabschnittes auf dem oberen Ende des wenigstens einen Vertikalrohrs.
• Anheben des Säulenelementes und Verlagern desselben relativ zu dem Vertikalrohr, wobei der in einer vorbestimmten Errichtungshöhe zu errichtende Bauwerkabschnitt auf einem oberen Ende des Säulenelementes ruht. Dieses Anheben geschieht solange, bis der Bauwerkabschnitt, der also mit angehoben wird, die vorbestimmte Errichtungshöhe erreicht hat.
• Festlegen des Säulenelementes an dem Vertikalrohr, um ein Absinken des erstgenannten zu verhindern, also die Konstruktion mit dem in der Errichtungshöhe angeordneten Bauwerkabschnitt gleichermaßen zu verriegeln.

With regard to a method for the establishment of an offshore structure to be erected with a building section at a predetermined erection height above the water surface, there is proposed one comprising the following steps:

• Lowering a base element, which has at least one fixedly connected to the latter vertical tube, said vertical tube has in its interior a relative to this displaceable in its longitudinal direction column element. This lowering takes place in the seawater down to the seabed in such a way that an upper, open end of the vertical tube is above the water surface, but below the construction height.
• Settling of the building section to be erected at the predetermined installation height on the upper end of the at least one vertical pipe.
• Lifting the pillar member and displacing it relative to the vertical pipe, wherein the building portion to be erected at a predetermined erection height rests on an upper end of the pillar member. This Lifting takes place until the building section, which is thus raised, has reached the predetermined installation height.
• Fixing the pillar element to the vertical tube to prevent a sinking of the former, so to lock the construction with the arranged in the building height section equally.

This method according to the invention has the particular advantage that the building section, which is to be spent up to the installation height, e.g. an onshore prefabricated inverter platform for the conversion of electrical AC voltage generated with wind turbines, can be spent without the use of a ship's crane and without the use of special high-built transport barges up to the installation height and connected there with the foundation. Because the supernatant of the open end of the vertical tube of the lowered base element above the water surface must be sufficient only so far that caused by during the construction phase by swell or ship movements waves do not reach the top of this open end and water enters the interior of the tube. However, for this purpose (depending on the peace of the lake) a height of the order of a few tens of meters (typically one to seven meters, for example five meters) is sufficient. At this height, a corresponding platform or other structure section can be conveniently spent with a common transport barge without high bodies and driven over the vertical tube. Then, such a platform can then be drained, for example, by flooding of ballast spaces in the transport barge and lowering the same and placed on the upper end of the vertical tube.

In this case, the building section on the upper end of the vertical tube itself, in particular on a there formed by the vertical tube circumferential, flared widened ring edge can be discontinued. Equally - and this falls within the meaning of the invention under a "settling of the building section on the upper edge of the vertical tube" - the building section can also on a projecting beyond the level of the uppermost edge of the vertical tube End of the column element are discontinued. If the settling done, it can be done by lifting the column member and displacing the same relative to the vertical tube lifting the building section up to the construction height. Finally, in order to fix the structure section at the erection level, the column element is fixed to the vertical tube. The construction of vertical tube and pillar element thus forms a total support for lying in the building height building section and at the same time the connection to the actual foundation, which is due to the base element. The base element itself can get the foundation alone because of its mass (for example, a weight of several tens of thousands of tons). Alternatively or additionally, the base element can also be anchored with appropriate connections in the seabed, for example by einzurammende anchoring elements. However, preference is given to a pure gravity foundation, since this is easier to remove again in the case of dismantling.

Before lowering the base element may - and will usually - a step of the preparation of the seabed at the site of the base element lie. For this purpose, the seabed is typically first dredged to an excavation and preparatory plan worked. Subsequently, a corresponding receiving bed, for example, a gravel bed, then introduced, leveled and deposited thereon, the base element. To prevent Unterspülens of the base element due to the water movements is typically arranged around the lowered and stepped base element so-called Kolkschutz. This can be done immediately after the lowering of the base element or else at any later time up to a time after completion of the further construction steps.

The base element itself is typically completed on land and must then be transported by sea to the sinking point of the foundation. In order to make this transport as simple as possible, it is proposed in an advantageous development of the invention that the base element is designed as a buoyant pontoon and that this thus initially floating is brought to the point at which it is to be lowered, wherein the lowering is done by flooding of ballast spaces in the pontoon. Thus, the pontoon-like base element can be spent, for example, by means of conventional tugboats (tractor) to the site of the offshore construction and then lowered there controlled by flooding the Ballasträume. Typically, the base element with upwardly projecting or upwardly projecting vertical tube (s), ie in an orientation, as it consists after lowering the base element, are brought to the installation site. This is to be preferred since the base element does not have to be rotated about a horizontal axis after it has been moved to the location where it is to be lowered, which typically, if at all, will only be possible with considerable effort.

In particular, when the building section is placed directly on the upper end of the vertical tube, that is not on a free end of the column member, it is advantageous if provided as in a further development of the invention, to this upper end of the vertical tube, for example, a circumferential ring edge, previously buffer or damper elements are placed. The building section, for example a converter platform or a living platform, can then be set down on these buffer or damper elements without damaging the substructure onto which it is set down. After lifting the column element, when the buffer or damper elements are exposed, they can be removed again and recycled at another site.

Also on the upper end side of the column member a buffer or damper element is advantageously placed, for example, an elastomer buffer. This typically remains permanently in the connection between the upper end of the column member and an underside of the building section supported thereon.

The lifting of the column element can in principle be undertaken by various possible means and by various suitable methods. For example, the use of spindle or hydraulic lifts for this purpose conceivable. It is also fundamentally possible to realize a lifting over at least part of the stroke by means of hydraulic pressure of seawater let into corresponding flutrms. In particular, however, lifting according to a particular embodiment of the invention advantageously takes place by means of at least one strand lifter, in particular by means of a plurality of strand lifters distributed along the circumference of the vertical tube. Strand jacks are particularly suitable for lifting heavy loads as they allow them to lift reliably. In an arrangement of a plurality of strand jacks, as not least due to the total weight to be lifted and also due to the need to avoid tilting during the lifting operation, is preferably provided, a controller will be provided which coordinates the lifting movements of the individual strand jacks with each other, to achieve a uniform and vertical lifting of the column member relative to the vertical tube. The strand jacks can be placed in particular in an externally accessible upper portion of the vertical tube, for example, on appropriate brackets and - including the Hublitzen - removed after successful setting of the column member on the vertical tube and used for a further use.

In order to prevent in particular a lateral tilting of the column member relative to the vertical tube or tilting of these two elements during lifting of the column member, during this lifting step, an active circumferential guidance can take place, in particular by means of radially to the column member Andrückbarer sliding and guide elements. By means of appropriate actuators, a specifiable force can be exerted on the sliding and guiding elements in order to keep the column element aligned with its longitudinal axis in the vertical direction and to ensure a jam-free lifting without tilting. In particular, corresponding slide and guide elements can be arranged in at least two sections arranged vertically one above the other, so as to ensure an even better alignment of the longitudinal axis of the column element during the lifting process.

In order to completely dismantle the building with the foundations after completion of use as completely as possible again, the setting of the column member is relative to the vertical tube releasably, in particular by means of screw. Such screw can on the one hand safely absorb the weight in the vertical direction of the column element itself and resting on the building section, they can on the other hand (assuming appropriate maintenance and sealing against corrosive influences) even after decades solve again for a simple dismantling. If the above-mentioned circumferential guides are provided, these can also be fixed to the column element at the end of lifting with a defined pressing force, in order to relieve corresponding actuators that have been used during lifting in order to apply the adjustable pressing force. Preferably, this fixation is releasably, whereby also screw can be selected here. Alternatively, but also welds are possible, which - with appropriate design - are also solvable by later with appropriate tools (for example, cutting discs or cutting torches) are released again. Also used to operate the sliding and guide elements or to move the same used in the radial direction of the column member actuators can be removed and removed at the end of the erection process to reuse them on other sites and thus to save costs.

Advantageously, after fixing the column element to the vertical tube, so after completion of all necessary work in the region of the upper end of the vertical tube, an annular gap between the vertical tube and the upper end of this emerging column member waterproof sealed. This prevents ingress of seawater into the vertical tube, even if the sea is rougher and higher waves occur, which wash over the upper end of the vertical tube. By preventing the entry of seawater into the interior of the vertical tube, it is particularly avoided that existing connections (for example those for fixing the column element to the vertical tube in the raised position) corrode and no longer - at least not simply - released at the time of a later dismantling can be. Also, the structures required, for example, for attaching the strand jacks or other lifting mechanisms, which are required in case of dismantling for lowering the column member as well as in the case of the structure for lifting.

The method according to the invention is in particular not limited to the fact that only a vertical tube with a column element arranged therein is arranged on the base element. Rather, two or more of such vertical tubes may be provided, each with a column member disposed therein, wherein the building section to be arranged in the installation height is then deposited on all upper ends of the vertical tubes (this in turn also includes settling on possibly protruding from these upper ends free ends of the column elements ) and is transported by lifting all column elements relative to the vertical tubes in the installation height. In this case, corresponding lifting mechanisms for all column elements are coupled to each other via a controller such that a uniform and in alignment, in particular a horizontal orientation, the building section constant lifting is guaranteed and it does not come in particular to a tilting due to an inclination of the building section. Corresponding controls are known in the art and already implemented, so need not be explained in detail here.

In particular, when the building section has a plane and flat surface, with which it is connected to the upper ends of the column elements, the upper ends of the vertical tubes or protruding from the upper ends of the column elements should span a substantially horizontal plane. In the case of heels or other offset in the course of the connection surface of the building section, the upper ends of the vertical tubes and the positions of the upper end faces of the column elements should naturally emulate the corresponding profile when receiving the building section.

• ein auf den Meeresgrund absenkbares Sockelelement mit wenigstens einem mit dem Sockelelement fest verbundenen Vertikalrohr, welches bei auf dem Meeresgrund abgesenktem Sockelelement mit einem oberen Ende oberhalb der Wasseroberfläche, jedoch unterhalb der Errichtungshöhe liegt;
• ein in dem Vertikalrohr angeordnetes, relativ zu diesem in dessen Längsrichtung verlagerbares Säulenelement; und
• Mittel zum Heben des Säulenelementes mit darauf auflastendem Bauwerkabschnitt bis zu der Errichtungshöhe.

An inventive foundation system, which may be advantageous and in particular a gravity-foundation system, for a in The offshore structure having a construction section to be erected above a predetermined surface area above the water surface has the following features:

• a lowerable to the seabed base element with at least one fixed to the base element vertical tube, which is located in lowered on the seabed base element with an upper end above the water surface, but below the installation height;
• an arranged in the vertical tube, relative to this displaceable in the longitudinal direction column member; and
• Means for lifting the column element with aufauflastendem building section up to the installation height.

With such a foundation system, the advantages already outlined above, in particular those of a simple introduction of the construction section to its construction height, can be achieved without the use of a crane or special transport barges having high structures.

Part of the foundation system are advantageously stranded jacks, which can be temporarily arranged and fixed there with Litzenantrieben on in the upper region of the vertical tube on the inside and on the wall mounting brackets and the Hublitzen, which with a free end at at a lower portion of the column member arranged stop devices can be struck. Such a configuration of the means for lifting the column member has the advantages already described above, bring the strand jacks with it. In addition, the strand jacks are temporarily usable and removable after lifting and in other ways carried out by the strand jacks setting the pillar element relative to the vertical tube, but can be arranged again, for example, to lower the pillar element again lowered into the vertical tube for retrieving the building section from the construction height.

The foundation system may further comprise buffer and damper elements, which can be temporarily applied to an upper edge of the vertical tube and removed again after the building section has been moved to the installation height. Further, at least one buffer element is advantageously arranged on the upper end face of the column element, on which rests the building section, even after completion of the assembly work, when the building section is in the building height and resting on the upper end of the column member. With this upper end face of the building section may also be connected with other suitable means, for example screwed or welded.

The foundation system also advantageously has connection structures for releasably connecting the column element to the vertical tube and fixing the former in its raised state. With regard to a fixation in the vertical direction, this can be, for example, by corresponding aligned holes on corresponding elements of the vertical tube and the column member guided threaded rods and fittings. For a fixation in the horizontal direction corresponding jaws can be brought to the periphery of the column member and fixed there with a certain contact pressure, for example, screwed and welded or otherwise, with a solvability should be respected here for a simple dismantling.

In particular, distributed over the circumference of the column member guide and sliding elements may be provided which are adjustable in particular by means of actuators in their directed to the column member pressure force. Such guide and sliding elements may in particular also be present in two levels arranged horizontally one above the other. About this can be applied by means of the actuators during lifting an adjustable and predetermined guide force, which also provides the correct orientation of the column member with its longitudinal axis to the vertical, on the column member. Incidentally, these guiding and sliding elements can at the same time obtain a lock in the horizontal direction even after complete lifting of the column element by be clamped with a predetermined pressure against the exterior of the column member and fixed there (see above description of the releasable fixation).

In order to be able to wait and inspect the structures of the foundation, in particular even after the building has been erected, it is advantageous if the column element is likewise tubular and there are inspection accesses to the interior of the vertical tube and also of the column tube. Corresponding access audits can also be performed to the extent that they allow an exit at the top of the pillar element, so that this access can allow for access to the remote at the upper end of the pillar element structure section itself, for example, after landing on the building of See here. Accordingly, such access may be made, for example, by a peripheral edge at the top of the vertical tube, here e.g. may have a secured by appropriate security grid or railing or the like to the sea.

The foundation system of the invention may, in particular in horizontally-projecting building sections to be installed at the erection level, not only one, but may comprise two or more and preferably more than two vertical tubes fixedly connected to the base element and in which in each case a height-displaceable with respect to the vertical tube column member is arranged with a corresponding connection for lifting means for lifting each of the column elements.

For reasons already described in more detail above, it is advantageous to design the base element together with the one or more vertical tube (s) arranged thereon as buoyant, in particular pontoon-like, element with ballast spaces, this element being filled by the ballast spaces with a ballast medium, in particular Seawater, which can be lowered to the seabed. So the base element can thus spent swimming to the place of use and lowered there by flooding the ballast chambers to the seabed, where it then forms the actual foundation. In this case, the base element a secure foundation already due to its high weight (for example, 40,000 tons) condition. But it can also be anchored for a secure foundation in addition to other anchoring elements in the seabed, eg with piles or the like. Preferably, however, is a simple gravity foundation. Because this allows the base element in a required deconstruction then, if all other elements have already been removed and the column elements lowered into the vertical tubes to lift from the seabed, in a buoyant base element in particular to empty the ballast rooms and in turn catch up and spend on land , There it can then be scrapped or restored for another use.

With particular advantage, the base element and the vertical tubes formed thereon are integrally formed of concrete, in particular steel-reinforced concrete and is the column member or the column elements are formed with an outer metal, in particular steel wall. The column elements can be designed in particular as steel tubes. The construction of the base element with the vertical tube formed thereon, including the column element inserted therein, advantageously takes place on land, e.g. in a dry dock. For the further construction, in particular the shipment to the place of use, it is then spent floating there, after the dry dock has been flooded and the column element has been discharged.

According to a further advantageous development of the foundation system, this sealing means for sealing the annular gap between the inner wall of at least one vertical tube and the outer wall of the column member disposed therein at the upper end of the vertical tube and in the raised position of the column member. Corresponding sealing means can, provided there is access to an interior to be sealed, also be provided for the sealing of the transition between the upper end face of the column member and the construction section placed thereon. This seal, which are applied in particular after the erection of the offshore structure, prevents ingress of water into these spaces and thus corrosion on these sections. In this way - assuming appropriate maintenance and care of the elements - it can be ensured that even after years of use of the structure, a controlled dismantling by "backward unwinding" of the steps taken during the construction is possible.

Fig. 1

eine schematische Ansicht eines Offshorebauwerkes mit einer erfindungsgemäß ausgebildeten Gründung in fertigem Zustand bei vollständig errichtetem Bauwerk;

Fig. 2

eine schematische Seitenansicht eines Sockelelementes eines erfindungsgemäßen Gründungssystems mit durch gestrichelte Linien kenntlich gemachten, im Inneren liegenden Strukturen;

Fig. 3

eine Aufsicht auf das Sockelelement gemäß Fig. 2 erneut mit durch gestrichelte Linien kenntlich gemachten, im Inneren des Sockelelementes liegenden Strukturen;

Fig. 4

in drei verschiedenen Ansichten a bis c eine Querschnittsdarstellung eines Ausschnittes einer Gründung mit einem Sockelelement wie in Figuren 2 und 3 dargestellt sowie mit einem in ein Vertikalrohr des Sockelelementes eingesetzten Säulenelement in drei verschiedenen Stellungen während des Aufbaus bzw. der Errichtung des Offshorebauwerkes;

Fig. 5

in vergrößerter Darstellung einen Ausschnitt aus Fig. 4a, nämlich den dortigen oberen Abschnitt des Vertikalrohrs mit daran angebrachten weiteren Elementen;

Fig. 6

in vergrößerter Darstellung einen Ausschnitt aus Fig. 4b, nämlich einen Ausschnitt, darstellend den oberen Abschnitt des Vertikalrohres mit einem unteren Abschnitt des darin angehobenen Säulenelementes;

Fig. 7

einen vergrößerten Ausschnitt aus Fig. 4c, nämlich einen oberen Abschnitt des Säulenelementes mit dem Anschluss an einen auf deren oberer Stirnfläche aufgesetzten Bauwerkabschnitt;

Fig. 8

einen weiteren vergrößerten Ausschnitt der Darstellung aus Fig. 4c, nämlich in vergrößerter Darstellung einen mittleren Abschnitt des Vertikalrohres mit dem unteren Abschnitt des Säulenelementes und der Verbindung zwischen Vertikalrohr und Säulenelement nach erfolgtem Errichten des Bauwerkes;

Fig. 9

eine Aufsicht auf das obere Ende des Vertikalrohres gemäß der in Fig. 5 eingezeichneten Blicklinie A;

Fig. 10

eine Schnittdarstellung gemäß der in Fig. 4a bezeichneten Schnittlinie B;

Fig. 11

eine Schnittdarstellung gemäß der in Fig. 6 bezeichneten Schnittlinie C;

Fig. 12

eine Schnittdarstellung gemäß der in Fig. 8 dargestellten Schnittlinie C;

Fig. 13

eine schematische Darstellung des Ablaufes für den Bau und die Aufstellung der erfindungsgemäßen Gründung sowie die Errichtung des Offshorebauwerkes auf der Gründung;

Fig. 14

in schematischer Darstellung eine Anordnung einer Gruppe von gleichartigen Bauwerken in nebeneinander angeordneter Aufstellung und gegründet auf dem Meeresgrund mit dem erfindungsgemäßen Prinzip;

Fig. 15

in schematischer Darstellung mit drei verschiedenen Ansichten a, b und c eine weitere und andere konstruktive Ausgestaltung einer erfindungsgemäßen Gründung für ein Offshorebauwerk.

Further advantages and features of the invention will become apparent from the following description of an embodiment with reference to the accompanying figures. Showing:

Fig. 1

a schematic view of an offshore structure with an inventively designed foundation in the finished state with completely built structure;

Fig. 2

a schematic side view of a base element of a foundation system according to the invention with indicated by dashed lines, located in the interior structures;

Fig. 3

a plan view of the base element according to Fig. 2 again with indicated by dashed lines, lying in the interior of the base element structures;

Fig. 4

in three different views a to c is a cross-sectional view of a section of a foundation with a base member as shown in Figures 2 and 3 and with a column used in a vertical tube of the base element column element in three different positions during the construction or the establishment of Offshorebauwerkes;

Fig. 5

in an enlarged view a section of Fig. 4a namely, the upper portion of the vertical tube with additional elements attached thereto;

Fig. 6

in an enlarged view a section of Fig. 4b namely a cutout representing the upper portion of the vertical tube with a lower portion of the pillar member raised therein;

Fig. 7

an enlarged section Fig. 4c namely, an upper portion of the column member with the connection to a mounted on the upper end face structure section;

Fig. 8

another enlarged section of the presentation Fig. 4c namely, an enlarged view of a central portion of the vertical tube with the lower portion of the column member and the connection between the vertical tube and column member after the construction of the structure;

Fig. 9

a plan view of the upper end of the vertical tube according to the in Fig. 5 drawn line of sight A;

Fig. 10

a sectional view according to the in Fig. 4a designated section line B;

Fig. 11

a sectional view according to the in Fig. 6 designated section line C;

Fig. 12

a sectional view according to the in Fig. 8 illustrated section line C;

Fig. 13

a schematic representation of the process for the construction and installation of the foundation according to the invention and the construction of the offshore structure on the foundation;

Fig. 14

a schematic representation of an arrangement of a group of similar structures in juxtaposed formation and founded on the seabed with the principle of the invention;

Fig. 15

in a schematic representation with three different views a, b and c another and other structural design of a foundation according to the invention for an offshore structure.

In the figures, possible embodiments of a erfindunsgsgemäßes method or an inventive foundation system are shown schematically and are explained below. The drawings represent no claim to detailed completeness and / or scale justice. Rather, they are to be understood as sketches which, where essential inventive details are described, represent these in great detail, but are simplified in other respects from a possible fully comprehensive construction illustration.

In Fig. 1 First, an example of a fully built offshore structure 1 is shown, which has a foundation system according to the invention for connection to the subsurface at sea and has been constructed with a method according to the invention for forming such a foundation with respect to the foundation. The offshore structure 1 contains a building section 2, which is set up and erected at a construction height h _E above the waterline W. This building section 2 may in particular be a converter platform for converting electrical energy generated by offshore wind turbines, but it may also include a different structure and function, for example a residential platform for accommodating marine and maintenance personnel, a work platform or the like.

The building section 2 rests on a foundation structure 3, which contains a pedestal element 4 set down on the seabed M. The base element 4 comprises a base 5 which is plate-shaped in this exemplary embodiment, but which can in principle also accommodate other shapes, but which always serves to support it on the seabed M or on a substructure previously attached there. Arranged on the base 5 and in particular integrally connected thereto are vertical tubes 6, which run substantially vertically and are located above the waterline W with their upper, open ends 7. The base element 4 is placed with its base 5 on a gravel bed 8, which has been set up in a previously excavated on the seabed M pit and worked plan. At its side regions, the base element 4 is surrounded by a scour protection 9.

From the upper ends 7 of the vertical tubes 6 protrude out of support columns 10, which are defined with lower portions in the vertical tubes 7 in a manner to be described later. Resting on the upper end surfaces of these support columns 10 the structure section 2. Its weight is vertically discharged via the support columns 10, the vertical tubes 6 and the base member 4 on the seabed M and so carried.

In Fig. 1 Finally, the trajectory of a design wave, which is used in the design of the erection height h _E , is entered with B. This design wave indicates a maximum wave height to be expected according to predetermined probability criteria for which the offshore structure 1 is designed and in which, in particular, the construction section 2 still has to protrude safely out of the turbulent sea, ie the water and without flooding. This design wave B thus has an immediate influence on the determination of the installation height h _E.

By the reference numeral 11, a dip pipe is indicated, which is lowered from the building section 2 in the seawater and is used for the suction of seawater for the purpose of cooling of arranged in the building section 2 to be cooled components. Furthermore, 12 indicates a cable guide, which enters laterally into the base 5 of the base element 4, extends through the interior of a vertical tube 6 and the support column 10 arranged therein up to the building section 2. Along this cable guide 12, for example, an incoming power cable can be guided, which feeds electrical energy generated by a wind turbine connected to a converter platform as a building section 2 to the inverter platform.

In FIGS. 2 and 3 is in two different views, one side view ( Fig. 2 ) and a plan view ( Fig. 3 ), the base element 4 shown again. Shown here are hidden inside structures, which are indicated here by dashed lines.

In the areas in which not the vertical tubes 6, of which the base element 4 has a total of four, which are arranged at the corners of a rectangle, partition walls 13 are provided, between which ballast rooms 14 are located.

The base element 4 is formed in this embodiment of steel-reinforced concrete, the concrete in its properties, in particular with regard to its density and porosity, is selected and designed so that it over a many years and decades of continuous use and a corresponding installation in seawater, in particular with the upper ends of the vertical tubes 6, which are formed as well as the base equally made of this concrete, in the region of the transition zone between seawater and surrounding air can withstand.

The base element 4 is formed integrally with its components base 5 and vertical tubes 6 in particular. The arranged inside the base 5 partitions 13, which leave between 14 Ballasträume, are also made of concrete in this embodiment, although they may consist of other material in the same manner. In this case, the base element is designed such that it is buoyant in empty (ie air-filled) Ballasträumen 14, achieved by flooding the Ballasträume 14 a higher density and thus can be lowered to the seabed. Depending on the weight of the offshore structure to be accommodated with the foundation and the expected forces in the horizontal direction due to wind load and loads due to the water movement, the mass of the base element 4 is designed. It is typically several tens of thousands of tons, especially if, as in Fig. 1 represented and preferably the foundation is designed as a pure gravity foundation, so should be done without further anchorages in the seabed alone by the patch in the prepared bed on the seabed base element.

In the FIGS. 4a to c in each case a section of the foundation structure 3 according to the invention in different temporal situations during the construction of the offshore structure 1, in particular the attachment and erection of the building section 2 is shown in a longitudinal section. Enlarged clipping representations are too Fig. 4a in Fig. 5 , too Fig. 4b in Fig. 6 and to Fig. 4c in the FIGS. 7 and 8th shown. In the following explanation of the representation of FIG. 4 in the individual representations a to c is accordingly and with regard to special structures on the associated, above characters 5 to 8 Reference is made, in which individual details are presented in improved visibility and partially only provided there with reference numerals.

In Fig. 4a First, the state is shown in which the foundation structure 3 is already lowered to the seabed. However, the support columns 10 are not yet in the Fig. 1 shown position in which the building section 2 rests on the upper front ends in the building height h _e . Rather, a situation is shown here in which the support columns 10 are arranged in their entirety in the interior of the vertical tubes 6, are lowered or retracted therein. Here it can be seen that the vertical tubes 6 have a sufficiently large inner diameter in order to accommodate the support columns 10 in itself. In the embodiment shown here, the support columns 10 disappear altogether in the vertical tube, so that in this state, the support columns 10 with their upper front ends do not protrude beyond the upper end 7 of the respective vertical tube 6. The support columns 10 are steel wall pipes in this embodiment. You are in the Fig. 4a shown lowered output and arranged relative to the vertical tube 6 in the longitudinal direction of said elements slidably inside in each vertical column 6. In this state, in each case a lifting drive and a bundle of guided through this and connected to it in operative connection Stroke 16 comprehensive strand jacks 17 for lifting the support columns 10 are provided. The lifting lugs 16 extend vertically to a lower end of the respective support column 10 and are there struck stop devices 18. In each vertical column 6 while strand lifter are arranged in a greater number along the circumference, wherein the lifting actuators 15 are arranged on formed on the inner wall of the vertical tubes 6 mounting brackets 19 and fixed there.

Furthermore, it can be seen on a widened, at the upper end 7 to the vertical tube 6 encircling annular pad 20 patch damper elements 21, which may be, for example, formed with spring packs spring damper. Furthermore, 23 further damper elements 24 are arranged at the upper end 22 of the support columns 10 each on a widened circumferential annular connection surface, which may be, for example, elastomer damper. In the Fig. 4a and in enlarged detail in FIG Fig. 5 is now shown a situation in which the building section 2, of which only a portion of its bottom is shown, is placed on the upper ends 7 of the vertical tubes 6, wherein a parking is here on the damper elements 21. With a protuberance 25, which corresponds in diameter substantially to the inner diameter of the support column 10 and is formed with downwardly tapered walls, the bottom of the building section 2 is deposited so that this protuberance 5 protrudes into the interior of the support column 10. The damper elements 21 serve on the one hand to buffer a settling of the building section 2 on the upper ends 7 of the vertical tubes 6 otherwise to be feared shock, on the other hand, they get a certain balance of horizontal if necessary given unevenness, so if individual of the vertical tubes not exactly complete their upper ends on a vertical support plane.

If the building section 2 then deposited in the manner described above on the upper ends 7 of the vertical tubes 6, this process can be described in more detail below, it is by lifting, ie relative displacement in the vertical upward direction, the support columns 10 relative to the vertical tubes 6 and out of these from the upper ends 7 out in the direction of the building height h _e spent. This is done until the in Fig. 4b shown final state is achieved with the help of the strand jacks 17, which are controlled for a uniform lifting for each vertical tube 6 with each other and with respect to the respective vertical tubes with each other are in coordination to get an exact carried out with a constant horizontal alignment of the building section 2 lifting. The final state then reached is in Fig. 4b shown with an enlarged sectional view of the upper portion of a vertical tube 6 in Fig. 6 ,

In this lifting provide Leit- and sliding elements 26 which are distributed in two arrangement levels segmentally horizontally around the circumference of the support column 10, with corresponding cylindrical section formed guide surfaces, especially those made of plastic, for an exact vertical guidance of Support column 10. In order to exercise this guidance and to make an alignment of the support column 10 with its longitudinal axis in the vertical direction, actuators 27 are arranged between the inner wall of the vertical tube 6 and a guide surface, which may be, for example, hydraulic cylinder. These can be controlled individually in their pressure force so that alignment and sufficient guidance of the support column 10 is made possible during the lifting process.

When lifting the support column 10 first reaches the upper end 22 with the damper elements 24 with a bottom of a bottom wall of the building section 2 into engagement, and it is so attached to the upper ends 23 of the support columns 10 building section 2 together with the support columns 10 is lifted. Accordingly, the strand jacks 17 are selected dimensioned and dimensioned in number so that they not only the weight of the support columns 10, but also the load of the building section 2 can raise.

If the in Fig. 4b shown state is reached, the already shown in this illustration no longer placed on the pad 20 damper elements 21 can be removed.

In the Fig. 6 Moreover, it can still be seen that at the lower end of the support column 10, a towing platform 28 is arranged, which is provided for necessary during a lifting operation, if necessary, or also for subsequent maintenance and service work and is accessible. It can - even after the finished erection of the offshore structure - the interior of the support columns 10 and thus the vertical tubes 6 are achieved by a closed with a corresponding door or a bulkhead access opening 29 in the lateral surface of the support column 10 in the fully raised state the support column 10 is ideally located at the height of the upper end 7 of the vertical column 6, so that this upper end 7 can be used with its connection surface 10 as circulation and access. For a vertical movement in the Inside the support column 10 corresponding ladders or similar ascending and descending means are provided.

In the further course of the construction work, after completion of the lifting process, the in Fig. 4c shown and in excerpts according to FIGS. 7 and 8th illustrated situation created. For this purpose, the support column 10 is fixed in the vertical column 6 in the raised state. With still mounted Litzenhebern 17 and jammed by the lifting drives Hublitzen screw connections between the vertical tube 6 and the support column 10 are created. For this purpose, threaded rods 30 are guided by vertical openings in retaining brackets 31 on the inner wall of the vertical tube 6 and by further aligned with these openings openings in a arranged at the lower end of the support column 10 rotating extension section 32. The threaded rods are then screwed, in particular with screw on a on the Holding bracket 31 upwardly projecting portion and below the delivery section 32 downwardly projecting portion. These threaded rods 30 carry or transmit the vertical loads. Horizontal loads are removed from the support column 10 on the vertical tube 6 via the guide and sliding elements 26, which are pressed for this purpose with a predetermined pressure against the outer wall of the support column 10 and locked there in a suitable manner, for example by screwing or attaching a welded joint between previously movable against each other and movable by means of the actuators 27 elements. The actuators 27 are removed in this state, since they are no longer needed for the pure load transfer and "lock".

Are these described and in Fig. 8 made closer connections between support column 10 and vertical tube 6, the stranded jacks 17 are removed, for which purpose first the lifting lugs 16 are released from their attachment points and subsequently solved the lifting actuators 17 of the mounting brackets 19 and removed.

Subsequently, an annular space seal 33 is placed on the vertical tubes 6 at the upper end 7 and brought up to the outer wall of the support columns 10, to seal the gap between the inner wall of the vertical tube 6 and the outer wall of the support column 10 against a possible ingress of seawater. This annular space seal 33 can be created, for example, by applying steel plates with corresponding seals in the region of the support on the upper end 7 of the vertical tube 6 and in the region of the connection to the outer wall of the support column 10. The annular seal 33 can at the same time one of maintenance personnel or the like. Walk Represent bottom of a circulation, from which the access opening 29 can be reached.

At the upper end of the support column 10, a seal in the form of a sealing hood 34 is also provided after removal of the Hublitzen 16. This is at points where previously the Hublitzen were attached to the upper end of the support column 10, screwed with threaded bolts 35. In the connection areas in which the sealing hood 34 rests against the surface of the support column 10 or the underside of the building section 2, sealing structures 36 (in FIG Fig. 7 further illustrated in an enlargement) is provided, which also provides mutually, for example, due to different thermal expansion against each other working elements continue to provide a sufficient seal against water ingress or other fernzuhaltende from this area substances.

In the FIGS. 9 to 12 are taken along in the illustrations according to Fig. 4 to Fig. 8 shown lines top views or sections shown to further illustrate the structure and its arrangements. In Fig. 9 can be particularly well the uniform along the circumference on the pad 20 at the upper end 7 of the vertical tube made arrangement of damper elements 21 recognize how it is initially provided. It can also be clearly seen here that a multiplicity of damping elements 24 are arranged in a uniform distribution over the circumference on the annular connection surface 23 at the upper end 22 of the support column 10. Finally, the uniformly distributed over the circumference arrangement of strand jacks 17, in the embodiment shown, these are twelve pieces, the number is by no means limited to this is, rather, according to respective circumstances can be selected to recognize.

The sectional view in Fig. 10 shows particularly well the delivery section 32 in the lower end of the support column 10 within the vertical tube 6 arranged therein, the stop structures 18 forming openings for connecting the Hublitzen the strand lifters and through holes 37, through which the threaded rods 30 for connecting the support column 10 with the vertical tube 6 in raised state and then screwed.

The in Fig. 11 shown section along the line C in Fig. 6 allows the retaining bracket 31 to recognize the inner wall of the vertical tube 6 and the arrangement of it attached in this plane, circumferentially surrounding the support column 10 guiding and sliding elements 26, with their cylinder section curved, resting on the outside of the support column 10 contact surfaces and in this illustration arranged actuators 27 for adjusting and adjusting the guide and sliding elements 26th

In the sectional view to Fig. 12 can be seen in the same sectional plane that there the guide and sliding elements 26 are no longer connected to the actuators 27, they are removed. Rather, the guide and sliding elements 26 are now fixed, for example, welded or screwed to press with a predetermined pressing force on the outer periphery of the support column 10 and to absorb corresponding horizontal forces. Also to be seen here are the upper, screwed ends of the threaded rods 30, the upward from in the retaining bracket 31 introduced through openings 38 (see. Fig. 11 ) protrude.

In Fig. 13 is - divided into twelve phases - the basic procedure when erecting the provided with the invention foundation offshore construction shown schematically. In this case, the base 5 of a base element is produced in a dry dock D in a first phase. When this base 5 is completed, the dry dock D is flooded and the base is discharged in phase 2. Due to the arranged in the base 5 Ballasträume 14, in this Phase are without ballast filling, the base 5 is buoyant. In phase 3, the base element 4 is completed by construction of the vertical tubes 6 at fixed to a quay wall or the like. Base 5, and there are the support columns 10 and the other internals used for the lifting mechanism. The foundation structure 3 prepared in this way is then brought to the construction site by sea with a tugboat S (or several such tugboats). In this case, the design of the ballast spaces compared to the total mass of the foundation structure 3 and the volume is such that the foundation structure 3 is floatable, so how a floating pontoon can be spent to the construction site. At the construction site, as described schematically in phase 7, the foundation structure 3 is lowered by controlled flooding of the ballast spaces on a set-up ground, which had been previously prepared by digging a pit G and introducing the gravel bed 8. With the upper ends 7 protrude the vertical tubes 6 from the water and lie with these areas above the waterline W. in phase 8 of the scourer 9 is attached. In phase 9 of the building section 2, for example, a completely finished inverter platform for an offshore wind farm, for example by means of a transport barge positioned relative to the upper ends of the vertical tubes 6 so that it can be placed in the desired position on it. Subsequently, the building section 2 is lowered, for example by flooding of ballast rooms in the Transportbarge T and lowering their draft. Thus, the position shown in phase 10 is reached, in which the transport barge is pulled off and the building section 2 rests securely on the upper ends of the vertical tubes 6. Subsequently, the lifting is carried out as described above and fixing the support columns 10 relative to the vertical tubes 6, so that the building section 2 then rests in the predetermined installation height above the water surface W and the offshore structure 1 is completed in total.

In Fig. 14 schematically shows that with the foundation according to the invention also a plurality of Offshorebauwerken 1 can be arranged side by side in the composite, each of the Offshorebauwerke 1 has its own foundation structure 3 between the bases 5 of the respective foundation structures 3 only sufficient Kolkschutz 9 is provided.

In Fig. 15 Finally, in two representations a and b schematically outlines an alternative embodiment of a foundation according to the invention or a foundation system. The essential difference here is that a base element 40 is provided, which has a circular contact surface and only a vertical tube 6, in which the support column 10 in the manner described above relative to the support tube 6 is displaceable and arranged after this fixable. Also on such a foundation system, a building section 2 can be arranged at a construction height h _E above a water surface W. Again, it's like Fig. 15a results, the base element 40 dimensioned such that in the lowered state, the upper end 7 of the vertical tube 6 above the water surface W, however, below the erection height h _e .

The procedure for erecting a building on such a foundation or for attaching the foundation is analogous to that described above, so that reference may be made to the above statements.

As can be seen in particular from the embodiment illustrated last, the specific configuration with respect to the geometry and shape of the foundation may be different, will be selected depending on the particular application.

LIST OF REFERENCE NUMBERS

1

offshore construction

2

building section

3

foundation structure

4

base element

5

Base

6

vertical tube

7

top end

8th

gravel

9

Scour protection

10

support column

11

dipleg

12

cable management

13

partition wall

14

ballast room

15

Linear actuator

16

Hublitzen

17

strandjack

18

stop device

19

mounting bracket

20

terminal area

21

damper element

22

top end

23

Ring pad

24

damper element

25

protuberance

26

Guide and sliding element

27

actuator

28

drag stage

29

access opening

30

threaded rod

31

retaining bracket

32

boom section

33

Annulus seal

34

sealing cap

35

threaded bolt

36

sealing structures

37

Through opening

38

Through opening

40

base element

B

design wave

D

dry dock

G

excavation

h _E

construction height

M

seabed

S

tow boat

T

transport Barge

W

waterline

Claims (18)

1. Method for laying the foundation of an off-shore construction to be erected with an edifice section in a preset erection height above the water surface with the following steps:

   a) Lowering a base element with at least one vertical pipe fixedly connected therewith, which includes in its inside a column element movable relative thereto in its longitudinal direction, on the seabed so that an upper, open end of the vertical pipe lies above the water surface, however below the erection height,

   b) Descending the construction section to be erected in the pre-established edifice height on the upper end of said at least one vertical pipe,

   c) Raising the column element and moving the same with respect to the vertical pipe, whereas the construction section to be erected in a pre-established erection height rests on an upper end of the column element, until the construction section has reached the pre-established erection height,

   d) Fixing the column element to the vertical pipe, to prevent it from sinking.
2. A method of claim 1, characterised in that the base element is designed as a buoyant pontoon and is then floatingly brought to the position at which it must be lowered, whereas the lowering consists in flooding ballast chambers in the pontoon.
3. A method as claimed in one of the preceding claims, characterised in that first of all buffer or damping elements are placed on the upper end of the vertical pipe, on which the construction section is placed in step b) and said are preferably removed again after completed raising of the column element.
4. A method as claimed in one of the preceding claims, characterised in that the column element is raised by means of at least one lifting jack, preferably by means of several lifting jacks distributed along the periphery of the vertical pipe.
5. A method as claimed in one of the preceding claims, characterised in that during the lifting process of the column element in step c) the latter is actively guided circumferentially by means of sliding and guiding elements which can be pressed radially to the column element.
6. A method as claimed in one of the preceding claims, characterised in that the column element was fixed in a detachable way with respect to the vertical pipe, in particular by means of screw connections.
7. A method as claimed in one of the preceding claims, characterised in that after step b) an annular gap is sealed in a water-tight fashion between the vertical pipe and the column element coming out therefrom in the region of the upper end of the vertical pipe.
8. A method as claimed in one of the preceding claims, characterised in that the base element contains two or more vertical pipes fixedly connected thereto, in which respectively in the inside a column element which is movable relative to the respective vertical pipe in its longitudinal direction, whereas in step b) the construction section to be erected in the pre-established erection height is lowered on the upper ends of all vertical pipes and then in step c) all column elements are raised simultaneously and coordinated in such a way that the construction section is counterweighted in place up to the erection height.
9. A foundation system, in particular a gravity foundation system, for an offshore construction (1) containing a construction section (2) to be erected in a pre-established erection height (hE) above the sea level (M) with a base element (4) which can be lowered on the seabed (M) and at least one vertical pipe (6) fixedly connected to the base element (4), a vertical pipe which lies on a base element (4) lowered on the seabed (M), with an upper end (7) above the water surface (W), however below the erection height (hE),

   a) with a column element (10) arranged in the vertical pipe (6), which can be moved with respect to the said in its longitudinal direction and

   b) means (17) for raising the column element (10) with construction section (2) bearing thereon up to the erection height (hE).
10. The foundation system of claim 9, characterised by assembly consoles (19) arranged in the upper area of the vertical pipe (6) on the inner side on the wall thereof, through stop devices (18) arranged an a lower section of the column element (10) as well as through lifting jacks (17 with lifting strands (16) and lifting drives (15) and means for transient connection of the lifting strands (16) with the stopping devices (18) as well as means for transient fastening of the lifting drives (15) to the assembly consoles (19).
11. The foundation system according to one of the claims 9 or 10, characterised by at least one buffer element (24) arranged on the upper front side (23) of the column element (10), in particular an elastomer buffer.
12. The foundation system according to one of the claims 9 to 11, characterised by connection structures (30) for releasable connection of the column element (10) with the vertical pipe (6) and fastening the first one in its raised condition.
13. The foundation system according to any of the preceding claims, characterised in that the column element (10) is also tubular and that inspection accesses (29) are provided in the inside of the vertical pipe (6) and of the column pipe (10).
14. The foundation system according to one of the claims 9 to 13, characterised by guiding and sliding elements (26) arranged in the vertical pipe (6), oriented radially in the inside thereof and distributed over the circumference of the column element (10), whose pressing force oriented to the column element (10) can be adjusted in particular by means of actuators (27).
15. The foundation system according to one of the claims 9 to 14, characterised in that least two, preferably more than two vertical pipes (6) are arranged fixedly on the base element (4), which protrude over the water surface (W) with their open upper ends (7) when the base element (4) is lowered and placed on the seabed (M), but rest below the erection height (hE) and which span an essentially horizontal bearing plane with their upper ends (7), whereas a column element (10) is arranged in each of the vertical pipes (6), in the longitudinal direction of the respective vertical pipe (6) and mobile relatively to the latter.
16. The foundation system according to one of the claims 9 to 14, characterised in that the base element (4) including the vertical pipes (6) arranged thereon, is designed as a buoyant element, in particular in the form of a pontoon, fitted with ballast spaces (14), which element can be lowered on the seabed (M) by filling the ballast chambers (14) with a ballast medium, in particular sea water.
17. The foundation system according to one of the claims 9 to 15, characterised in that the base element (4) and the vertical pipes (6) formed thereon, are designed as single pieces of concrete, in particular steel armoured concrete, and that the column element (10) presents an external metal wall, in particular a steel wall.
18. The foundation system according to one of the claims 9 to 16, characterised by sealing means (33) for sealing the annular slit between the internal wall of said at least one vertical pipe (6) and the external wall of the column element (10) arranged therein at the upper end (7) of the vertical pipe (6) and in raised position of the column element (10).

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