EP3597829B1 - Foundation reinforcement for offshore construction - Google Patents

Description

area

The invention relates to a foundation reinforcement for an offshore structure.

background

Foundations or foundation structures for offshore structures or offshore structures, especially for offshore wind turbines or topsides (e.g. built-on dwellings for electrical systems, substations, platforms, to name just a few examples) sometimes require increasing load requirements during operation which must then be borne by the corresponding foundation.

For example, it can happen that an oil drilling platform as an offshore structure should produce more oil during operation, or should offer increased security against weather conditions or the like. Furthermore, for example, in wind turbines as an offshore structure, the load requirement can increase during operation, if z. B. a larger turbine, or larger rotor blades should be included in the wind turbine. Then it is necessary that the existing foundation of the offshore structure can also bear these increased load requirements.

It is often disadvantageous that the existing and used foundations are not designed for these higher loads. For example, structures have e.g. B. Lattice elements of jacket foundations themselves have in some cases already experienced a considerable proportion of planned fatigue loads. Furthermore, retrofitting additional lattice structures of a (jacket) foundation is sometimes costly, since the new lattice structures result in an increased modal mass that reduces the natural frequency of the Offshore structure and thus the fatigue loads of the existing foundation are usually increased. This is mainly due to the fact that the natural frequency of the offshore structure moves closer to the excitation frequency of the wave spectrum of the sea.

From the WO 2014/115435 A1 a foundation for an offshore platform is known, with support elements forming part of the foundation. The support elements are firmly connected on the underside with barrel-like elements and on the upper side with a plane. The support elements are also connected by means of connecting elements to an inner ring, which is also formed from barrel-shaped components.

From the US 2017/0233971 A1 a foundation system for the foundation of an offshore structure, comprising a monopile with an anchoring section which can be anchored in the seabed and a connecting section arranged at the opposite end is known. A platform structure can be connected directly or indirectly via a transition piece to the connecting section of the monopile. The foundation system also has stabilizing devices in the form of support feet, which are connected to the platform structure and to the seabed.

the GB 2481906 A deals with the task of simplifying the installation of foundations in the seabed. For this purpose, a temporary scaffolding for installing supports or pillars underwater is disclosed. The frame has a plurality of support legs, the support legs comprising vertically adjustable foot parts. Struts can be placed between the support legs to reinforce them. The support legs can be used as a template to drill holes for pillars, for example a jacket foundation.

From the NL 1026005 C1 a foundation for an offshore platform is known that can be assembled entirely locally from modular parts. The modular foundation has a foundation device, a platform, anchoring arms and pre-tensioned cables. The anchoring arms are connected by means of diagonal struts to a centrally arranged, vertical support pillar. The anchoring arms are also connected to a tensioning device arranged below the platform by means of the pre-tensioned cables.

the US 2011/0135400 A1 discloses a foundation for an offshore platform in which additional support of a vertical main pillar is achieved via struts. For this purpose, the struts are arranged between the main pillar and supporting pillars. The foundation is also known as a jacket foundation.

General description of some exemplary embodiments

It would be desirable, in particular, to be able to adapt existing foundations to the load requirements of an offshore structure which increase during operation.

Against the background of the state of the art presented, the objective task is to at least partially reduce or avoid the problems described, i.e. in particular to provide a cost-effective way of adapting an existing foundation of an offshore structure to increasing load requirements during operation to be able to.

• zumindest ein im Wesentlichen vertikal verlaufendes Stützelement mit einem oberen Ende und einem unteren Ende, wobei das untere Ende fixiert ist;
• zumindest ein Kragelement, das von dem oberen Ende des Stützelementes zu einem von einem ersten Verankerungsabschnitt einer bestehenden Gründung gehaltenen Element des Offshore-Bauwerks zumindest teilweise horizontal hinauskragt;
• wobei das Stützelement und das Kragelement derart an der bestehenden Gründung anordenbar sind, dass eine auf das Element wirkende Kraft zumindest teilweise über das Kragelement auf das Stützelement und/oder (z. B. direkt) auf das Stützelement übertragbar ist, so dass eine Entlastung der bestehenden Gründung erzielbar ist,
• wobei die die bestehende Gründung eine Jacket-Gründung ist;
• wobei zumindest zwei Stützelemente und zumindest zwei Kragelemente an der bestehenden Gründung anordenbar sind; und
• wobei die jeweiligen oberen Enden der zumindest zwei Stützelemente mittels zumindest eines Tragelementes miteinander verbindbar sind.

According to an exemplary aspect of the invention, a foundation reinforcement for an offshore structure is disclosed, comprising:

• at least one substantially vertically extending support element having an upper end and a lower end, the lower end being fixed;
• at least one cantilever element which protrudes at least partially horizontally from the upper end of the support element to an element of the offshore structure held by a first anchoring section of an existing foundation;
• wherein the support element and the cantilever element can be arranged on the existing foundation in such a way that a force acting on the element is at least partially via the cantilever element on the support element and / or (z. B. directly) is transferable to the support element, so that a relief of the existing foundation can be achieved,
• where the existing foundation is a jacket foundation;
• wherein at least two support elements and at least two cantilever elements can be arranged on the existing foundation; and
• wherein the respective upper ends of the at least two support elements can be connected to one another by means of at least one support element.

Some exemplary embodiments are described in more detail below:
The term seabed in the context of the invention encompasses both a seabed of a sea (e.g. ocean) and a seabed of a lake.

The invention is based on the knowledge that bearing reserves of anchors (e.g. foundation piles) in the seabed of existing foundations can be mobilized. Furthermore, it is possible to keep the load increase in (the structure) of the existing foundation (e.g. jacket foundation) caused by the increased load requirement of the offshore structure. Furthermore, the necessary changes and adjustments to the existing foundation or its structures (structural elements) are kept low by means of the foundation reinforcement according to the invention.

According to the invention, the loads or increased loads of the offshore structure are diverted via the foundation reinforcement in question into at least one mainly vertically oriented support element, which is fixed with its lower end near the seabed or near the seabed. The lower end of the at least one support element is, for example, non-positive, e.g. B. fixed with one or more anchors (e.g. foundation piles) of the existing foundation by being connected to them (e.g. screwed and / or grouted).

The element of the offshore structure is, for example, a pile element which has at least one vertical connection to a useful structure or topside of the offshore structure. Furthermore, the element of the offshore structure is, for example, a fastening point of the offshore structure, preferably a fastening point on an underside (i.e. in particular a side facing the seabed) of the offshore structure.

An offshore structure is, for example, a wind turbine installed offshore. Furthermore, an offshore structure is, for example, a transformer station, or a drilling or production platform. An offshore structure is, for example, a structure founded in the sea floor that has or includes a topside.

For the purposes of the invention, a topside of an offshore structure in particular denotes that part of an offshore structure which is arranged above sea level and comprises functional elements of the offshore structure. In the case of a wind power installation as an offshore structure, this can be, for example, the nacelle comprising a turbine and rotor blades, the nacelle being founded, for example, via a tower by means of the existing foundation in the seabed. Topides of the offshore structure can also be, for example, dwellings for electrical systems, substations, oil and / or gas production and processing systems, measuring and radio stations, residential platforms, loading stations, flares or the like, to name just a few non-limiting examples .

The at least one support element is, for example, a pipe. The lower end of the support element is fixed so that a force can be diverted or diverted. For example, the lower end of the support element is fixed in such a way that the force is diverted or diverted into the sea floor.

The at least one cantilever element is, for example, a horizontal support. The at least one cantilever element is ideally connected to all existing elements (e.g. pile elements) that support the offshore structure.

The objective reinforcement of the foundation allows increasing loads on the offshore structure to be borne by the existing foundation during ongoing operation. According to the invention, this is made possible in particular by the fact that anchors (e.g. one or more foundation piles) of existing foundations are subject to so-called growth effects, which the present invention makes use of. This is an increase in the resistance of the anchoring (e.g. foundation pile) of the existing foundation in the seabed. B. result from rearrangements and settlement effects and the reduction of pore water pressures. These growth effects can increase the maximum load of the anchorages of the existing foundations by 20% to 60% and more. This opens up the possibility of subsequently significantly increasing the stability of offshore foundations for loads that act on these offshore foundations by means of the foundation reinforcement in question, without the existing anchoring (e.g. one or more foundation piles) having to be renewed.

In an exemplary embodiment of the object, the existing foundation engages with at least one second anchoring section of an anchorage that can be anchored in the sea floor.

The existing foundation includes, for example, one or more anchors, e.g. B. Foundation piles anchored in the seabed. The one or more anchors (e.g. foundation piles) are anchored in the sea floor, for example, in such a way that the second anchoring section, which is comprised by the anchoring of the existing foundation, engages in the sea floor. This can be made possible, for example, in that the one or more anchorages are at least partially vibrated into the sea floor, so that the respective second anchoring section of the one or more anchors engages in the seabed.

The existing foundation is a jacket foundation.

Certain offshore structures, in particular wind turbines, are regularly attached to the sea floor with a jacket foundation.

Such a jacket foundation has, for example, a square base, which are connected to one another with a pyramid-shaped framework construction made of lattice structures (e.g. steel tubes), the pyramid-shaped construction extending vertically upwards. An upper end of the lattice structure is designed, for example, to receive the element (e.g. pile element) from the offshore structure. The lower end of the jacket foundation itself is anchored in the sea floor, for example by means of at least one anchorage (e.g. foundation pile).

The existing jacket foundation is anchored, for example, with a pre-pile anchoring in the sea floor, with one or more anchoring elements or anchors (e.g. pile elements) of the jacket foundation being anchored in the sea floor so that the jacket foundation can be anchored in the sea floor is. This is realized, for example, in which the lattice structure (s) of the jacket foundation, e.g. B. by means of a grouting, in which or the anchor (s) is fixed.

Alternatively, the existing jacket foundation is, for example, a post-pile anchoring, whereby with the post-pile anchoring the arrangement of the foundation reinforcement in question is sometimes easier than with a pre-pile anchoring. In the case of post-pile anchoring of a jacket foundation, the lower end of the at least one support element of the foundation reinforcement is arranged (e.g. inserted) into at least one free upper end of at least one foundation piles comprised by the respective post-pile anchors, and in particular then positively connected to the respective post-pile anchorage (e.g. fixed), e.g. B. by means of a grouting.

An increase in rigidity is made possible by enlarging the "jacket headprint" and relieving the lattice structure (s) of the existing jacket foundation.

In an exemplary embodiment of the object, the support element and the cantilever element can be connected to one another in a non-positive manner.

The upper end of the at least one support element and one end of the at least one cantilever element can, for example, be firmly connected to one another (for example screwable or weldable). A direction of longitudinal extension of the at least one support element and a direction of longitudinal extension of the at least one cantilever element have, for example, an angle of approximately 90 ° in the present case. In this way, the longitudinal direction of the at least one support element in the state reinforcing the existing foundation is essentially vertical, and the longitudinal direction of the at least one cantilever element in the state reinforcing the existing foundation is at least partially horizontal.

In an exemplary embodiment of the object, the support element can be positively connected to a foundation pile of the existing foundation.

The foundation pile is, for example, the anchorage that has the second anchorage section of the existing foundation. The existing foundation has, for example, more than one such foundation pile, e.g. B. two, three, four, or more such foundation piles. Such a foundation pile has, for example, at least one receptacle for receiving the lower end of the at least one support element. In order to fix the at least one support element in this receptacle, the lower end of the at least one support element can for example, intervene in the receptacle (z. B. be plugged in), and then be routed. The receptacle is designed accordingly, for example, as a hollow cylinder, so that the lower end of the at least one support element can engage in this hollow cylindrical receptacle.

In an exemplary embodiment of the object, the lower end of the support element engages the seabed with a force fit.

Alternatively to the fixation of the lower end of the at least one support element in a receptacle which, for. B. is provided by an anchoring (z. B. foundation pile) of the existing foundation, the lower end of the at least one support element can be fixed, for example (directly) in the seabed. A non-positive fixation in the seabed can be achieved, for example, by regrinding the lower end of the at least one support element (for example a section of the at least one support element). Furthermore, a non-positive fixation in the sea floor can be implemented, for example, by vibrating at least part of the lower end of the at least one support element into the sea floor.

The at least one support element is, for example, rotated with respect to one or more anchoring sections or anchors (e.g. one or more foundation piles) of the existing foundation, so that the lower end of the at least one support element is anchored directly in the seabed, and yet the at least one support element is essentially vertically aligned per se.

This described twisting of the at least one support element is particularly preferred with an existing jacket foundation that is designed as a pre-pile anchorage, as this enables easier assembly of the foundation reinforcement in question even with such a pre-pile anchorage of the existing foundation.

The lower end of the at least one support element is arranged, for example in the state reinforcing the existing foundation, essentially centrally between two anchors (e.g. foundation piles) of the existing jacket foundation (e.g. pre-pile anchors).

In an exemplary embodiment of the object, the support element is connected to a buoyancy body in a non-positive manner.

Such a buoyancy body in the sense of the present subject-matter has the effect that, with the foundation in question, extreme misalignments can be avoided or compensated for in the short and long term by causing a restoring force that counteracts the misalignment.

In particular, such a buoyancy body can have an essentially conical or curved geometry.

Such a buoyancy body can, for example, be used in addition to a foundation and support the holding of the offshore structure founded with the foundation.

The buoyancy caused by the (for example at least one) buoyancy body can result in a lower natural frequency of the offshore structure, as a result of which the natural frequency can be limited. This is due in particular to a semi-floating foundation of the offshore structure, which includes at least one buoyancy body.

In a further embodiment according to all aspects, the at least one buoyancy body is arranged below the surface of the water and / or at least encircles the element of the offshore structure in a horizontal plane.

Alternatively, in the upright state of the element of the offshore structure, the at least one buoyancy body can be arranged resting on the waterline. Furthermore, the at least one buoyancy body can be arranged, for example, on at least one arm extending from the outer wall of the element of the offshore structure.

In an exemplary embodiment of the object, the support element and the cantilever element together form an outrigger construction, which is arranged on the outside of the existing foundation in the state that reinforces the existing foundation, so that the existing foundation is stiffened at least one connection, preferably two connections, e.g. B. is formed rigidly between the vertically extending and the horizontally extending element and the existing structure and horizontal element.

A reinforcement, for example, of the elements (e.g. pyramid-shaped lattice structures) of the jacket foundation is made possible by this outrigger construction. The phrase "in the state reinforcing the existing foundation" in the sense of the present invention represents in particular that state in which the foundation reinforcement according to the invention is completely mounted on the existing foundation, i.e. the at least one cantilever element with at least one (supporting) element of the offshore Connected structure and the lower end of the at least one support element is fixed.

This also allows a cost-effective retrofitting of the foundation reinforcement in question on an existing foundation, since the work required for installation is minimal due to the simple external arrangement.

At least two support elements and at least two cantilever elements can be arranged on the existing foundation.

In the state reinforcing the existing foundation, at least two, preferably three, four or five support elements can consequently be arranged on the outside of the existing foundation. Correspondingly, for example, in the state that reinforces the existing foundation, at least two, in particular three, four or five cantilever elements are each connected to the element of the offshore structure and the respective support element. All support elements and cantilever elements then reinforce this existing foundation in the state that reinforces the existing foundation.

Furthermore, the at least two support elements and the at least two cantilever elements can be arranged, for example, in a modular manner on the existing jacket foundation, so that the existing foundation can be successively expanded by one or more additional support elements and cantilever elements according to the invention, so that the existing foundation can be reinforced step by step. Furthermore, in the event that at least two support elements and at least two cantilever elements are arranged on the existing foundation, these are arranged, for example, evenly distributed on the outside of the existing foundation.

In an exemplary embodiment of the object, the at least one support element can be filled with a filling material to increase its own weight.

To accommodate the filling material, the at least one support element is, for example, at least partially hollow or hollow-cylindrical. For example, the at least one support element is a (hollow) tube.

The filling material is, for example, a cement suspension. The filling material is pressed or cast into the at least one support element, for example

In an exemplary embodiment of the object, the element of the offshore structure comprises a flange connection, wherein the cantilever element can be connected to the flange connection in a force-locking manner.

The at least one cantilever element can be arranged (for example screwed) on the flange connection, for example.

In the event that the element of the offshore structure is a pile element, this is arranged, for example, on the flange connection. In this way, the cantilever element can, for example, also be arranged on the flange connection (for example screwed on). Furthermore, the cantilever element of the foundation reinforcement in the sense of the present subject matter is also, for example, positively connected to the element of the offshore structure held by the first anchoring section of the existing foundation. Alternatively, the objective reinforcement of the foundation includes other configurations of the connections which, for. B. but not exclusively made by welding, screwing, gluing, riveting, jamming (also referred to as swaging), and / or are made by friction connections.

In order to be tolerant of strong deflections and also to be able to withstand extreme loads due to a high degree of deformability, the foundation reinforcement can, for example, allow the offshore structure to move widely. Correspondingly, the at least one cantilever element can for example be connected to the element of the offshore structure in such a way that it extends in a substantially vertical direction along the element (e.g. a pile element (e.g. tower in the case of an offshore wind turbine)) of the offshore structure can slide in the longitudinal direction of the element from the offshore structure. This makes it possible, for example, that inclining and / or rolling movements of the offshore structure (e.g. inclining and / or rolling movements of the tower of an offshore wind turbine) do not have such strong tensions in the at least one cantilever element and / or the at least trigger a support element of the foundation reinforcement that this can lead to material failure.

In an exemplary embodiment of the object, the at least one support element is designed telescopically so that its length can be changed and it is under tension in a state that reinforces the existing foundation.

This allows, for example, a simplified assembly of the at least one support element by, for. B. is initially shortened with its lower end fixable, and is then extended in length by means of the telescopic design, so that the upper end, which, for example, with the at least one cantilever element z. B. is connected, can be brought to the intended position. Then, for example, the free end of the at least one cantilever element can be fixed or non-positively connected to the element of the offshore structure.

The respective upper ends of the at least two support elements are connected to one another by means of at least one support element.

This further increases the reinforcement that can be achieved by the objective reinforcement of the foundation, since the force to be diverted or diverted can furthermore be at least partially transmitted between the at least two support elements or cantilever elements.

In an exemplary embodiment of the object, the foundation reinforcement causes an increase in the natural frequency of the offshore structure in a state that reinforces the existing foundation, so that a reduction in the natural frequency of the offshore structure caused by additional loads can be compensated for.

An increase in the (structural) natural frequency, i.e. the natural frequency of the offshore structure, compared to the natural frequency of the natural frequency of the structure changed by additional loads, is made possible back to the original frequency, with this "new" natural frequency of the structure ideally no more than 0.2 Hz below the original natural frequency.

In an exemplary embodiment according to all aspects, the offshore structure is a wind power plant that includes a power generation plant, e.g. B. comprises a turbine and a rotating component (z. B. rotor blade).

The objective object is also achieved by a foundation, including an objective reinforcement of the foundation.

The object of the invention is also achieved by an offshore structure, comprising a concrete foundation reinforcement.

The exemplary embodiments of the present invention described above in this description should also be understood to be disclosed in all combinations with one another. In particular, exemplary configurations should be understood in relation to the different aspects disclosed.

In particular, the previous or following description of method steps in accordance with preferred embodiments of a method should also disclose corresponding means for carrying out the method steps by preferred embodiments of a device. Likewise, the disclosure of means of a device for performing a method step is also intended to reveal the corresponding method step.

Further advantageous exemplary embodiments of the invention can be found in the following detailed description of some exemplary embodiments of the present invention, in particular in connection with the figures. However, the figures are intended only for the purpose of clarification, but not for determining the scope of protection of the invention. The figures are not true to scale and are only intended to reflect the general concept of the present invention by way of example. In particular, features contained in the figures should by no means be regarded as a necessary part of the present invention.

Brief description of the figures

Fig. 1

eine schematische Darstellung einer Jacket-Gründung für ein Offshore-Bauwerk umfassend eine gegenständliche Gründungsverstärkung;

Fig. 2

die schematische Jacket-Gründung für ein Offshore-Bauwerk nach Fig. 1 dargestellt im vollständig die Jacket-Gründung verstärkenden Zustand;

Fig. 3

eine schematische Darstellung eines Offshore-Bauwerks umfassend eine zweite und eine dritte Variante einer gegenständlichen Gründungsverstärkung; und

Fig. 4

eine schematische Darstellung eines Offshore-Bauwerks umfassend eine vierte Variante einer gegenständlichen Gründungsverstärkung.

In the drawing shows

Fig. 1

a schematic representation of a jacket foundation for an offshore structure comprising an objective foundation reinforcement;

Fig. 2

the schematic jacket foundation for an offshore structure Fig. 1 shown in the state fully reinforcing the jacket foundation;

Fig. 3

a schematic representation of an offshore structure comprising a second and a third variant of a concrete foundation reinforcement; and

Fig. 4

a schematic representation of an offshore structure comprising a fourth variant of a concrete foundation reinforcement.

Detailed description of some exemplary embodiments

Fig. 1 shows a schematic representation of a jacket foundation 2 for an offshore structure 3 comprising an objective foundation reinforcement 1. In FIG Fig. 1 a first variant of a concrete foundation reinforcement 1 is shown.

The offshore structure 3 is, for example, a wind turbine (in Fig. 1 not shown), the element 7 of the offshore structure 3 being, for example, the tower of the wind turbine. The offshore structure 3 is here established with a jacket foundation 2 as an existing foundation. The jacket foundation 2 has an anchoring section 6, which in the present case is a flange connection. It can be seen that the element 7 of the offshore structure 3 is held in the center of the flange connection in the present case. The element 7 of the offshore structure 3 is held, for example, in the anchoring section 6 of the existing jacket foundation 2, in which the element 7 of the offshore structure 3 is routed in the existing jacket foundation 2.

The jacket foundation 2 in the present case has four anchors 8 which are arranged at corner points of a rectangular basic shape of the jacket foundation 2. Each of these four anchorages 8 is designed as a foundation pile 8 in the present case. Each of these foundation piles 8 has at its lower end an anchoring section 8a, by means of which the respective foundation pile 8 can engage in the seabed, so that it is then anchored.

In Fig. 1 In the present case, two objective foundation reinforcements 1 are already arranged on the existing jacket foundation 2, two more objective ones However, foundation reinforcements 1 are not yet. These latter are in Fig. 1 to the left of the existing foundation 2, slightly offset upwards and shown at a distance from the existing foundation 2.

The two concrete foundation reinforcements 1, which according to Fig. 1 are not yet arranged on the existing foundation 2, in the present case comprise a support element 9 which connects the upper ends 4b of the respective support elements 4 or the respective ends of the cantilever elements 5, which are (firmly) connected to the respective upper ends 4b of the respective support elements 4 , connects with each other. Another such support element 9 is already on the upper end 4b of the support element shown on the left, which according to FIG Fig. 1 is not yet arranged on the existing jacket foundation.

Fig. 2 shows the schematic jacket foundation 2 for an offshore structure Fig. 1 when fully reinforcing the jacket foundation 2. For the sake of clarity, in Fig. 2 only one of the four represented foundation reinforcements 1 is provided with detailed reference numerals (in Fig. 2 the foundation reinforcement 1) shown on the right by the observer.

In contrast to Fig. 1 the two objective foundation reinforcements 1 are now also shown in the state reinforcing the existing jacket foundation 2.

It can be seen that the respective lower ends 4a of the support elements 4 are each fixed in one of the four receptacles 8b comprised by the foundation piles 8. For this purpose, the respective lower end 4a of the support elements 4 was inserted into the hollow-cylindrical receptacle 8b of the respective foundation pile 8, and then grounded in this.

Overall, the existing jacket foundation is 2 of the Fig. 2 reinforced with four concrete foundation reinforcements 1, with their respective cantilever elements 5 each with element 7 of an offshore structure 3 (in Fig. 2 not shown in full) are positively connected. Furthermore, the respective upper ends 4b of the support elements 4 are each connected to the upper ends 4b of their respective adjacent support elements 4 with a support element 9. An upper end 4b of a support element 4 consequently has a connection to two support elements 9.

Furthermore, in Fig. 2 the sea floor M is shown schematically, so that it is made clear that an anchoring section 8 a of a respective foundation pile 8 of the existing foundation 2 engages with this anchoring section 8 a in the sea floor M.

Fig. 3 shows a schematic representation of an offshore structure 3 comprising a second and a third variant of a concrete foundation reinforcement 1.

The offshore structure 3 in Fig. 3 is present a platform, z. B. a working platform of a conveyor system. This platform was founded with the existing foundation 2. In the present case it can be seen that the existing foundation 2 is a jacket foundation 2, the lattice structures of which extend above sea level so that the platform is not in the sea.

The second variant of a concrete foundation reinforcement 1 is in Fig. 3 shown on the left. The third variant of a concrete foundation reinforcement 1 is in Fig. 3 shown on the right.

The second variant of the foundation reinforcement comprises at least one essentially vertical support element 4 with an upper end 4b and a lower end 4a, the lower end 4a being fixed in the receptacle 8b of the foundation pile 8. Another support element of the same type is shown in Fig. 3 not to be seen for perspective reasons, since it is covered by the "front" support element. The length of the support element 4 is predefined, ie in particular it cannot be lengthened or shortened.

The support element 4 is also connected at its upper end 4b to a cantilever element 5. The upper end 4b of the support element 4 of the second variant extends to an element 7 held by the existing foundation 2, in this case the platform of the offshore structure 3 other part also extends in the vertical direction. In the sense of the present subject matter, a cantilever element 5 of the foundation reinforcement in question, which extends at least partially in the horizontal direction, can correspondingly also extend at least partially in the vertical direction. In contrast to this, the longitudinal extension direction of the support element 4 in the sense of the invention has only a slight deviation of a maximum of 10 to 15 degrees from a completely vertical axis. Other configurations include one or more inclined outrigger elements that either rise or descend from the existing structure and are connected to the element that largely leads vertically downwards. This also includes elements that are curved or that deviate from the vertical by more than 15 degrees.

In the present case, the cantilever element 5 is permanently connected to the offshore structure 3 at two anchoring sections with the element 7 (platform). The support element 4 and the cantilever element 5 are arranged on the existing foundation 2 in such a way that a force acting on the element 7 (platform of the offshore structure 3) at least partially via the cantilever element 5 on the support element 4 and / or directly on the support element is transferable, so that a relief of the existing foundation 2 by means of the foundation reinforcement 1 can be achieved.

In contrast to the support element of the second variant, the support element 4 of the third variant, shown on the right-hand side of FIG Fig. 3 , is designed telescopic, so that it can be changed in length. This particularly facilitates the assembly of the support element 4, since, for example, an erection of the support element, so that its longitudinal direction is arranged to run essentially vertically, can sometimes be difficult, since a non-telescopic support element 4 of the second variant sometimes jams between the receptacle 8b of the foundation pile 8 and the element 7 (in this case the platform) of the offshore structure 3 can be before it is arranged in the existing jacket foundation 2 reinforcing state. This is avoided by means of the telescopic support element 4. When the telescopic support element 4 of the third variant is arranged in the state reinforcing the existing jacket foundation 2, it is pretensioned in such a way that the existing foundation 2 can be relieved by means of the foundation reinforcement 1 in question.

Fig. 4 shows a schematic representation of an offshore structure 3 comprising a fourth variant of a concrete foundation reinforcement 1.

The offshore structure 3 in Fig. 4 is present a platform, z. B. a working platform of a conveyor system. This platform was founded with the existing foundation 2. In the present case it can be seen that the existing foundation 2 is a jacket foundation 2, the lattice structures of which extend above sea level so that the platform is not in the sea.

In contrast to the in Fig. 3 The second and third variant of the concrete foundation reinforcements 1 shown in FIG Fig. 4 The fourth variant shown (identical on the left and right side in Fig. 4 ) each have support elements 4, which are designed as tension elements. The respective support elements 4 are fixed with their respective upper ends 4b on the element 7, in the present case at a fastening point of the offshore structure 3 (e.g. on the underside of the offshore structure, in this case on the underside of the platform). Furthermore, the respective support elements 4 are fixed with their lower ends 4a in receptacles 8b of the foundation piles 8 of the existing foundation 2, for. B. by means of a grouting. By designing the respective support elements 4 as tension elements cause the support elements 4 so each a tensile force with the z. B. the attachment point of the offshore structure 3 and / or the receptacle 8b of the respective foundation pile 8 can be pulled.

The exemplary embodiments of the present invention described in this specification and the respective optional features and properties cited in this regard should also be understood to be disclosed in all combinations with one another. In particular, the description of a feature encompassed by an exemplary embodiment - unless explicitly stated to the contrary - should not be understood in the present case in such a way that the feature is essential or essential for the function of the exemplary embodiment. The sequence of the method steps described in this specification in the individual flowcharts is not mandatory; alternative sequences of the method steps are conceivable. The method steps can be implemented in various ways, so implementation in software (by means of program instructions), hardware or a combination of both is conceivable for implementing the method steps.

Terms used in the claims such as “comprise”, “have”, “include”, “contain” and the like do not exclude further elements or steps. The phrase “at least partially” includes both the case “partially” and the case “completely”. The phrase “and / or” should be understood to the effect that both the alternative and the combination should be disclosed, that is to say “A and / or B” means “(A) or (B) or (A and B)”. The use of the indefinite article does not exclude a plurality. A single device can perform the functions of several units or devices mentioned in the patent claims. Reference symbols given in the claims are not to be regarded as restrictions on the means and steps used.

List of reference symbols

1

Foundation reinforcement

2

existing foundation

3

Offshore structure

4th

Support element

4a

lower end of the support element

4b

upper end of the support element

5

Cantilever

6th

Anchoring section of the existing foundation (e.g. flange connection)

7th

Element of the offshore structure

8th

Anchoring / foundation pile

8a

Anchoring section of the anchorage

8b

Holder for support element

9

Support element

M.

Seabed

Claims (13)

1. Reinforcement for a foundation (1) for an offshore structure (3), comprising:

   - at least one substantially vertically extending support element (4) having an upper end (4b) and a lower end (4a), the lower end (4a) being fixed;

   - at least one cantilever element (5) which cantilevers at least partially horizontally from the upper end (4b) of the support element (4) to an element (7) of the offshore structure (3) supported by a first anchoring portion (6) of an existing foundation (2);

   - wherein the support element (4) and the cantilever element (5) are arrangable on the existing foundation (2) in such a way that a force acting on the element (7) is transmittable at least partially via the cantilever element (5) to the support element (4) and/or to the support element (4), so that a relief of the existing foundation (2) is achievable,

   - where the existing foundation (2) is a jacket foundation;

   - wherein at least two support elements (4) and at least two cantilever elements (5) are arrangable on the existing foundation (2); and

   - wherein the respective upper ends (4b) of the at least two support elements (4) are connected to each other by means of at least one carry element (9).
2. Reinforcement for a foundation (1) according to claim 1, characterized in that the existing foundation (2) engages with at least a second anchoring portion (8a) of an anchorage (8) in the sea bed (M), wherein the second anchoring portion (8a) is anchorable in the seabed (M).
3. Reinforcement for a foundation (1) according to one of the preceding claims, characterized in that the support element (4) and the cantilever element (5) are connectable to each other in a force-locking manner.
4. Reinforcement for a foundation (1) according to one of the preceding claims, characterized in that the support element (4) is connectable in a force-locking manner to a foundation pile (8) of the existing foundation (2).
5. Reinforcement for a foundation (1) according to one of claims 1 to 4, characterized in that the support element (4) engages in the seabed (M) with its the lower end (4a) in a force-locking manner.
6. Reinforcement for a foundation (1) according to one of the claims 1 to 4, characterized in that the support element (4) is connected to a buoyancy body in a force-locking manner.
7. Reinforcement for a foundation (1) according to one of the preceding claims, characterized in that the support element (4) and the cantilever element (5) together form an outrigger construction which, in the state reinforcing the existing foundation (2), is arranged externally thereto so that the existing foundation (2) is stiffened.
8. Reinforcement for a foundation (1) according to one of the preceding claims, characterized in that the at least one support element (4) is fillable with a filling material to increase its own weight.
9. Reinforcement for a foundation (1) according to one of the preceding claims, characterized in that the element (7) of the offshore structure (3) comprises a flange connection, wherein the cantilever element (5) is connectable to the flange connection in a force-locking manner.
10. Reinforcement for a foundation (1) according to one of the preceding claims, characterized in that the at least one support element (4) is of telescopic design so that its length is changeable and it is under prestress in a state reinforcing the existing foundation (2).
11. Reinforcement for a foundation (1) according to one of the preceding claims, characterized in that in a state reinforcing the existing foundation (2), the reinforcement (1) causes an increase in the natural frequency of the offshore structure (3), so that a reduction in the natural frequency of the offshore structure (3) caused by additional loads are compensable.
12. A foundation (2) comprising a reinforcement (1) according to any one of claims 1 to 11.
13. An offshore structure (3) comprising a reinforcement (1) according to any one of claims 1 to 11.

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