WO2023001879A1

WO2023001879A1 - Assembly for installing an above-surface structure in water-covered ground, in particular for the monopile-installation of an offshore wind turbine, and method for mounting same

Info

Publication number: WO2023001879A1
Application number: PCT/EP2022/070329
Authority: WO
Inventors: Andreas Denker; Nico GENGE; Ralf Hojda; Claas Bruns
Original assignee: Vallourec Deutschland Gmbh
Priority date: 2021-07-23
Filing date: 2022-07-20
Publication date: 2023-01-26
Also published as: DE102021119100A1

Abstract

The invention relates to an assembly (1) for installing an above-surface structure (8) in water-covered ground, in particular for the monopile-installation of an offshore wind turbine, having at least one coupling structure (3) resting on a ground (4) which can be anchored to the ground (4) via at least one foundation element (5) and to which a supporting structure (2) can be secured for supporting the above-surface structure (8). In order to achieve a high level of environmental compatibility for the foundation structure (1) during installation as well as to achieve simple and cost-effective installation, it is proposed that the at least one coupling structure (3) is arranged within the supporting structure (2), within a lower end (2a) of the supporting structure (2). The invention also relates to alternative methods for mounting this installing assembly (1) on ground (4).

Description

Assembly for installing an above-surface structure in water-covered ground, in particular for the monopile-installation of an offshore wind turbine, and method for mounting same

The invention relates to an assembly for installing an above-surface structure in water- covered ground, in particular for the monopile-installation of an offshore wind turbine, having at least one coupling structure which can be anchored to the ground via at least one foundation element and to which a supporting structure can be secured for supporting the above-surface structure.

The invention also relates to two alternative methods for mounting a corresponding assembly for installation purposes.

In conjunction with the present invention, above-surface structures are understood essentially as offshore plants, including offshore platforms and offshore wind turbines (OWTs). Offshore platforms also include so-called drilling rigs. Corresponding installations take place not only in the open sea near to a coast, but are also feasible in large lakes or inland sees. These usage locations are defined as water-covered ground in conjunction with the present invention.

Offshore plants, in particular OWTs, are typically anchored to the seabed at their intended location via so-called foundation structures. Corresponding, generally known foundation structures can essentially be divided into two structural areas. The first structural area is a highly fatigue-loaded supporting structure which begins on the seabed and ends at a connection to the tower of an OWT. The supporting structure thereby supports the tower and a turbine of the OWT and transfers the thereby produced loads and impacts. The second structural area includes at least one foundation element which absorbs the loads produced by the supporting structure, the tower and the turbine, dissipates said loads into the seabed and is predominantly located in the seabed beneath the supporting structure. The entire OWT thus consists of the foundation structure having the foundation element and the supporting structure as well as the tower and the turbine.

For installing an OWT in the seabed, it is known from German utility model specification DE 202010010094 U1 to use tubular driven piles as the foundation elements, which piles are driven into the seabed. Depending upon the design, the driven piles have a diameter of about 1.5 m to over 5 m. The number of driven piles used depends on the respective supporting structure. Different steel structures are used as a supporting structure for receiving the tower, in particular so-called tripile, tripod, jacketed and monopile supporting structures. In this case, the tripile, tripod and jacketed supporting structures formed with multiple legs are anchored in the seabed with each leg via a driven pile. In contrast, in the case of a monopile supporting structure formed with one leg, merely one steel tube is driven with its lower end into the seabed and so the steel tube of the supporting structure is simultaneously used as its driven pile.

Depending upon the structure and properties of the seabed, the driven piles are driven into the seabed to a depth of up to 65 metres. They reach a weight of about 220 to 700 tonnes, depending upon the properties of the seabed and choice of the supporting structure. The heavy pile hammers used for the driving process cause considerable noise and vibration emissions. These emissions are released into the air and also into the water and represent considerable pollution for nature and the environment.

International patent application WO 2013/113873 A2 discloses foundation structures having the aforementioned supporting structures, the anchoring of which no longer requires the driving of conventional driven piles into the seabed. Instead, drilled hole anchors or injection piles are drilled or vibrated into the seabed as foundation elements. The foundation elements thus introduced and anchored into the seabed without being driven manner are used to secure coupling structures, placed on the seabed, wherein each coupling structure is anchored in the seabed via a plurality of foundation elements. The respective supporting structures are secured to the seabed with their legs exclusively via one or more coupling structures. For this purpose, the coupling structures have a design composed of steel tubes in the form of a latticework, having a polyhedral, e.g. truncated pyramid, shape. In the case of tripile, jacketed and monopile supporting structures, each leg is placed centrally into a coupling structure and is enclosed and held in a frame-like manner by the coupling structure arranged around the leg on the outside. In this manner, the coupling structures form a type of adapter for connecting the legs of the corresponding supporting structure to the foundation elements.

German patent application DE 102007020483 A1 discloses an OWT, the foundation structure of which comprises a supporting structure formed as a monopile, wherein the monopile is simultaneously used as a driven pile. A tower of the OWT is slid with its lower end onto an upper end of the monopile or driven pile. In an overlapping region produced thereby, the lower end of the tower has a larger diameter than the driven pile. The overlapping region is defined by a tapering diameter of the tower. In the overlapping region, a concrete-like material is introduced between the tower and the driven pile, from which a so- called grout connection is produced between the tower and the driven pile or the monopile supporting structure.

European patent application EP 1 988219 A1 likewise discloses an OWT having a supporting structure which is formed as a monopile and is simultaneously used as a driven pile. In order to strengthen the anchoring of the monopile, a ring designated as a resistance plate is placed over the monopile. The ring surrounding the monopile lies underwater on the seabed and penetrates the seabed with circumferential edges at its inner and outer rims. Gravel is introduced between the inner rim and the driven pile.

German patent application DE 10349109 A1 discloses an OWT, the foundation structure of which comprises a supporting structure designated as a quadropod having four legs inclined outwards. Each leg of the supporting structure is connected to a driven pile which can be received or guided in the interior thereof and is guided out of the corresponding leg and driven into the seabed in a telescopic manner for anchoring in the seabed. The foundation structure also comprises a wheel-shaped connecting piece which lies on the upper end of the four legs for uniform load distribution and connects same to a tower of the OWT.

International patent application WO 2019/074363 A1 discloses an OWT having a foundation structure with at least three suction buckets which are anchored in a seabed. The buckets are connected via a star-like connection piece to a single upright tube. Moreover, sections of the tube are connected to each other by mechanical clamping.

Japanese patent application JP 2013-053425 A discloses an OWT with a tubular support structure divided into sections. For a connection of the sections adjacent ends of the sections having different diameters are inserted to each other and grout is filled into the gap between the ends.

German patent application DE 102013007237 A1 discloses an OWT comprising a monopile structure fixed in the seabed and additionally braced via bracing elements connected to additional foundation elements anchored in the seabed.

The object of the invention is to provide an improved assembly for installing an above surface structure in water-covered ground, in particular for the monopile-installation of an offshore wind turbine, and two alternative methods for mounting same, which can be achieved in a simple and cost-effective manner.

This object is achieved by an assembly for installing having the features of claim 1 and two alternative methods for mounting same having the features of claims 12 and 16. Dependent claims 2 to 11, 13 to 15, 17 and 18 describe advantageous embodiments of the invention.

An assembly for installing an above-surface structure in water-covered ground, in particular for the monopile-installation of an offshore wind turbine, having at least one coupling structure resting on a ground which can be anchored to the ground via at least one foundation element and to which a supporting structure can be secured for supporting the above-surface structure can be constructed in a particularly environmentally friendly and simple manner by virtue of the fact that the at least one coupling structure is arranged within the supporting structure, in particular within a lower end of the supporting structure. In particular, it is hereby possible to achieve a greater water depth for a foundation of monopiles. Currently, the maximum water depth for monopile foundations is about 45 m, but the monopile has a total length of about 80 m to 120 m because depending upon the seabed conditions, more than about 40 m thereof is driven into the ground. Using the assembly, in accordance with the invention, for installing an above-surface structure, the full length of the supporting structure can be utilised for installing purposes by way of securing the supporting structure via the coupling element to the ground.

The invention covers exclusively foundation structures according to one of the following types: monopile, tripod, quadropod, tripile or jacketed. Preferably, the foundation structure in accordance with the invention is used for supporting structures formed as monopiles. In particular, solid surface foundations and floating foundations designated as gravity-based foundations are, in contrast, not intended to be covered thereby.

In order to achieve a particularly stable and at the same time material-saving foundation structure, provision is made that the coupling structure is formed as a grid structure, in particular with a Vierendeel, framework or latticework design.

The supporting structure can be secured to the coupling structure in a particularly stable manner by virtue of the fact that the coupling structure has, starting from the ground, an upwardly tapering or widening extent or a barrel shape.

Securing the coupling structure to the ground is particularly facilitated by virtue of the fact that the coupling structure for the at least one foundation element forms a guide in which the at least one foundation element can be received prior to anchoring to the ground.

In a particularly low-noise and low-vibration manner, provision is made that the at least one foundation element can be anchored to the ground by means of drilling or vibrating.

By using a coupling structure anchored by means of drilled or vibrated foundation elements, it is possible to advantageously avoid the direct driving of driven piles for the supporting structure, in particular a supporting structure formed as a monopile at depths of up to 70 m. This also results in the fact that monopiles or, in the case of supporting structures formed with multiple legs, the legs thereof can be designed to be shorter or are suitable for greater water depths. The shorter supporting structures can then have correspondingly smaller wall thicknesses or can be intrinsically narrower. A lighter design for the supporting structure can also be achieved because the supporting structure or the monopile is provided with internal reinforcement owing to the arrangement of the coupling structure within the supporting structure.

A structurally particularly advantageous embodiment makes provision that the supporting structure can be secured to the coupling structure via a curing material, in particular a concrete mixture, which is introduced into the supporting structure. Advantageously, this renders superfluous the use of a transition piece, via which the otherwise unavoidable inclinations of driven-in driven piles, in particular of monopiles, have to be compensated for. The orientation of the entire foundation structure effected via a grout connection thus no longer has to be preformed via a transition piece between the support structure and tower, but rather can be effected in accordance with the present embodiment in a particularly advantageous manner between the coupling structure and the supporting structure, in particular the lower end thereof. Since the supporting structure is also no longer driven in and thus damage to the open end thereof is avoided, the tower of the OWT can also be received by the supporting structure via a flange connection and secured thereto. Instead of a curing material, a mechanical clamp e.g. via wedge, bayonet or bolt connections can also be provided.

In a structurally simple manner, provision is made that regions of the supporting structure or of the coupling structure contacted by the curing material have a compound-reinforcing, preferably fluted, surface structure. The steel-concrete-steel compound of the grout connection between the supporting structure, the curing material, provided e.g. in the form of a concrete mixture, and the coupling structure is hereby reinforced.

In an advantageous manner, the amount of curing material required for producing the grout connection can be reduced by virtue of the fact that a sheet metal covering is arranged on or within the coupling structure, wherein a filling region for the curing material which encloses the coupling structure is formed between the sheet metal covering and an inner wall of the supporting structure.

The stability of the grout connection is increased in a structurally simple manner by virtue of the fact that the filling region is annular and widens or tapers upwards, starting from the ground.

In an advantageous manner, the stability of the foundation structure or the supporting structure is increased by virtue of the fact that the supporting structure is braced via at least one outer additional anchoring, each having a bracing element.

Simple production of the foundation structure, in particular an advantageous reduction in the number of different parts, is achieved by virtue of the fact that the at least one additional anchoring is formed in the form of a coupling structure and can be anchored to the ground via foundation elements.

In a structurally simple manner, provision is made that the supporting structure is formed as a monopile.

A method for mounting an assembly, in accordance with the invention, for installing an above-surface structure in water-covered ground, in particular for monopile-installation of an offshore wind turbine can be performed in a particularly environmentally friendly and simple manner by virtue of the fact that in a first mounting step a coupling structure is arranged and secured within a supporting structure above water, in a second mounting step at least one foundation element is arranged in the coupling structure for anchoring the coupling structure to the ground, in a third mounting step the supporting structure is lowered with the coupling structure to the ground and the coupling structure is anchored to the ground via the at least one foundation element, in a fourth mounting step the supporting structure is oriented, and in a fifth mounting step the supporting structure is secured to the coupling structure.

Provision is advantageously made that in the first mounting step the coupling structure is releasably secured within a supporting structure, in the fourth mounting step the coupling structure is released from the supporting structure and the supporting structure is oriented with respect to the coupling structure.

Alternatively, provision is made that in the fourth mounting step the coupling structure is released from the supporting structure and the supporting structure is oriented with the coupling structure by securing the foundation elements to the coupling element.

The method is further improved by virtue of the fact that the second mounting step occurs whilst still above water or only after the lowering and subsequent dry-pumping of the coupling structure on the ground. Therefore, mounting work can also still be performed after the lowering of the coupling structure or the supporting structure to the ground. This may be necessary e.g. if - for coupling structures to be anchored particularly deeply in the ground - the foundation elements required for this cannot already be completely pre-mounted in the coupling structure and have to be further pushed on during anchoring, i.e. during drilling or vibrating.

An alternative method for mounting an assembly, in accordance with the invention, for installing on water-covered ground can be performed in a particularly environmentally friendly and simple manner by virtue of the fact that in a first mounting step at least one foundation element is arranged in the coupling structure for anchoring the coupling structure to the ground, in a second mounting step the coupling structure lowered to the ground is anchored to the ground via the at least one foundation element, in a third mounting step, the supporting structure is lowered to the ground and a lower end is placed over the coupling structure, whereby the coupling structure is arranged within the supporting structure, in a fourth mounting step the supporting structure is oriented with respect to the coupling structure and in a fifth mounting step the supporting structure is secured to the coupling structure. This method allows the coupling structure to be anchored to the ground virtually irrespective of the weather and, with sufficiently good weather conditions, allows the supporting structure to be placed on the coupling structure, used as a guiding spike, in a particularly simple manner.

The alternative mounting method can likewise be further improved by virtue of the fact that the first mounting step occurs whilst still above water or only after the lowering and subsequent dry-pumping of the coupling structure on the seabed.

It is particularly advantageous that the supporting structure is secured to the coupling structure by filling the supporting structure with a curing material or by mechanical clamping.

In addition, both mounting methods permit virtually complete pre-mounting of the individual components on land, and so smaller transport ships can advantageously be used owing to the smaller individual components.

An exemplified embodiment of the invention will be explained in greater detail with reference to the following description. In the drawing:

Figure 1 shows a schematic overall view of an OWT with a monopile supporting structure, Figure 2 shows a schematic detailed view of a foundation of the OWT according to figure 1 , Figure 3 shows a plan view of figure 2,

Figure 4 shows a schematic detailed view of a first alternative foundation of the OWT according to figure 1 with additional lateral bracing means,

Figure 5 shows a plan view of figure 4,

Figure 6 shows a schematic detailed view of a second alternative foundation of the OWT according to figure 1 with additional lateral bracing means,

Figure 7 shows a plan view of figure 6.

Figure 1 illustrates a schematic overall view of an above-surface structure 8 in the form of an offshore wind turbine (OWT) with a monopile supporting structure. The offshore wind turbine 8 typically has a rotor 8a which is rotatably mounted on a pod 8b which is supported at the top of a vertical tower 8c. At its lower end, the tower 8c is placed and secured on an installing assembly 1 - also called foundation structure. Such foundation structures are essentially divided into two structural areas which can be designated as supporting structure 2 and foundation element 5. The tower 8c rests on the supporting structure 2 which is formed as a monopile with a vertical and conical tube which tapers upwards and protrudes out of the water 9. The monopile tube can also be cylindrical. The supporting structure 2 is placed on ground 4 which, in the present case of an offshore wind turbine, is a seabed covered with water 9, and is anchored to the ground 4 via a coupling structure 3. For this purpose, the coupling structure 3 is connected on the one hand to an inner wall of the supporting structure 2 via a curing material 6 and on the other hand to the ground 4 via the foundation elements 5. Depending upon the structural size of the OWT, the coupling structure 3 has a height in the range of 25 m to 50 m. The foundation elements 5 protrude into the ground 4 in the range of 20 m to 70 m, depending upon the properties of the ground 4. Figure 2 shows a schematic detailed view of the assembly 1 for installing the above-surface structure 8 according to figure 1. The installing assembly 1 essentially includes the supporting structure 2 formed as a monopile, the coupling structure 3 and the foundation elements 5. In this case, the monopile is formed as a cylindrical tube, compared to the illustration in figure 1. In its operating state secured to the ground 4, the supporting structure 2 covers, with its lower end 2a, the coupling structure 3 and receives this so that the coupling structure 3 resting on the ground 4 is arranged inside the supporting structure 2 at a spaced disposition from the inner wall 2b of the supporting structure 2. The coupling structure 3 is anchored in or to the ground 4 by means of a plurality of foundation elements 5. The foundation elements 5 are preferably formed as drilled hole anchors or injection piles, in particular drilled hole injection anchors. Typically, the drilled hole anchors have a circumferential helical fin in order to support the drilling process. Such foundation elements 5 are introduced into the ground 4 and anchored there without being driven. Within the scope of the present invention, introducing or anchoring the foundation elements 5 “without being driven” is understood to mean that these are introduced into the ground 4 in a low-noise and low-vibration manner by means of drilling or by means of vibrating. This drilling or vibrating can be effected using electrical, pneumatic or hydraulic energy or combinations thereof. In this context, drilling is understood to mean the combination of rotating the foundation element 5 whilst moving it forward. The forwards movement can be effected with little force or with greater force in terms of pressing. Pulsating forwards movement is also feasible. Compared with driving, the forwards movement is not effected by a falling weight in terms of impact driving. For example, the so-called revolving technology using compressed air impact wrenches is applied here. In the case of vibrating, only pulsating forwards movement at a high frequency without rotation takes place. Compared to drilling or vibrating, driving is also effected at a lower frequency and with higher forwards movement energy. The supporting structure 2 extends, starting from the ground 4, substantially vertically upwards through and out of the water 9 (see figure 1). The supporting structure 2 formed as a monopile is a steel tube which can have a diameter of up to 12 m.

The coupling structure 3 is formed as a latticework grid structure and is arranged within the lower end 2a of the supporting structure 2. The coupling structure 3 is hereby used as a type of adapter for connecting the supporting structure 2 to the foundation elements 5 introduced into the ground 4 and anchored there. The coupling structure 3 additionally has, starting from the ground 4 upwards in the direction of the tower 8c, a tapering extent within the steel tube of the supporting structure 2, whereby the coupling structure 3 assumes the function of a type of guiding spike for the steel tube of the supporting structure 2 which can be placed over the coupling structure 3 at the top. In other words, the coupling structure 3, when lowering or placing the supporting structure 2 on the ground 4, is threaded into the lower end 2a of the supporting structure 2 and is received thereby.

In order to fixedly connect the coupling structure 3 lying on the ground 4 to the lower end 2a, likewise lying on the ground 4, of the supporting structure 2 placed over the coupling structure 3, the lower end 2a of the supporting structure 2 is filled with an organic and/or inorganic material 6, in particular one which also cures in water, for example a concrete mixture, and in this manner a so-called grout connection is produced between the coupling structure 3 and the inner wall 2b of the supporting structure 2.

The coupling structure 3 formed as a grid structure is designed in the form of a latticework. In the present exemplified embodiment, the grid structure has a truncated pyramid-shaped contour which tapers upwards starting from the ground 4, the square base surface 3a of which being able to be delimited by a ring or a plate. At its upper end of the coupling structure 3, a circular cover surface 3b is provided which likewise can be delimited by a ring or a plate and, as seen from above, is centred relative to the base surface 3a and is arranged within the circumferential region thereof (see figure 3). Tubular piles 3d are uniformly spaced apart from each other over the circumferential region of the base surface 3a, in particular in its corners 3c (see figure 3) and middle of its sides and are guided in an upwardly inclined manner to the cover surface 3b. The piles 3d are connected to the plates or rings of the base surface 3a or cover surface 3b. In addition, the piles 3d are connected together by means of circumferential horizontal struts which are spaced apart from each other over the height of the coupling structure 3, as well as via diagonal struts 3f, which struts are combined with the piles 3d to form the latticework- 1 ike design of the grid structure.

The piles 3d, the horizontal struts 3e and the diagonal struts 3f can consist of steel, concrete or composite materials and basically can have any polygonal, in particular triangular or rectangular, but also round, cross-section. It is also feasible for the piles 3d, the horizontal struts 3e and the diagonal struts 3f not to be tubular but to be formed as profiles having an open cross-section.

The coupling structure 3 is thus designed as a so-called jacketed structure and is thus arranged within the supporting structure 2 as a type of inner jacket.

Depending upon the loading, the grid structure or coupling structure 3 is formed as a three- dimensional structure having a cubic, truncated tetrahedron-shaped, conical, truncated pyramid-shaped or other type of polyhedral shape. Accordingly, the base surface 3a and also the cover surface 3b can be circular, triangular or rectangular, or another type of polygon and can be connected together via a wide variety of horizontal struts 3e and diagonal struts 3f. Instead of a latticework structure, the grid structure can also have a Vierendeel or framework structure in order to be able to dissipate the loads in an optimum manner. If the grid structure element has an angular base surface 3a, a pile 3d supported on the ground 4 is arranged at least in each corner 3c.

All of the piles 3d, in particular those arranged in the corners 3c, can be used as receiving tubes or guide tubes for the foundation elements 5 for anchoring the coupling structure 3 in the ground 4, and so separate guides or receptacles, arranged on the coupling structure 3, for the foundation elements 5 and the pre-mounting thereof on land are superfluous.

Basically, the foundation elements 5 can, however, be arranged at any location on the coupling structure 3. The connection between the foundation elements 5 and the coupling structure can be a form-fitting, force-fitting or an integrally bonded connection.

The surfaces of the coupling structure 3 enclosed by the curing material 6, in particular the piles 3d, horizontal struts 3d and diagonal struts 3f, are also provided with a surface structure, such as e.g. a fluted structure, for improved anchoring with the curing material 6 - similar to the case of reinforcing steel. The surfaces of the inner wall 2b of the monopile or of the supporting structure 2 also obtain a corresponding structure, e.g. by weld studs or a rolled fluted structure, thereby preventing sliding or displacement of the supporting structure 2 with respect to the coupling structure 3. The fluted structure produces a type of cogging with the curing material 6, whereby the steel-material-steel compound of the grout connection between the supporting structure 2, the curing material 6 and the coupling structure 3 is reinforced.

Furthermore, it is also possible to provide an inner space 3g enclosed by the coupling structure 3 and having a sheet metal covering 3h in order to reduce the amount of curing material 6 required for producing the grout connection. The sheet metal covering 3h is arranged in this case on sides of the piles 3d, horizontal struts 3e and diagonal struts 3f facing the inner space 3g. Therefore, a filling region 2c is produced between the sheet metal covering 3h and the inner wall 2b of the supporting structure 2, which filling region is wedge- shaped as seen in the sectional side view of figure 2 and widens towards the top. The filling region 2c thus includes the grid structure of the coupling structure 3 and excludes the inner space 3g, and so the grid structure can have curing material 6 flowing around it over the entire height, without the inner space 3g having to be filled with the curing material 6. Alternatively, provision can also be made to mechanically clamp the supporting structure 2 and the coupling structure 3 together.

It is also possible to provide a seal on the supporting structure 2, in particular on its lower end 2a so that at least the inner space 3g of the coupling structure 3 or even the entire supporting structure 2 can be evacuated underwater and made dry and can be entered as a water-free tunnel for mounting work. The supporting structure 2 or the coupling structure 3 or its inner space 3g can thus be water-tight. In this manner, the foundation elements 5 can also be dry-mounted only after placing the supporting structure 2 and coupling structure 3 arranged therein on the ground 4 beneath the water level W (see figure 1) and then anchoring is performed by drilling the foundation elements 5 into the ground 4.

As can be seen in figure 2, the installing assembly 1 preferably includes one foundation element 5 arranged centrally as a middle anchor and further foundation elements 5 arranged in the circumferential region of the coupling structure 3. Preferably, the central foundation element 5 is formed as a so-called pile root drill hole anchor and the foundation elements 5 in the circumferential region are formed as so-called drill anchor tubes or drall anchor tubes. Whilst the central foundation element 5 also extends vertically after the drilling process, the flexible foundation elements 5 in the circumferential region are drilled into the ground 4 vertically and are directed outwards as in the case of the so-called shale gas drilling. The produced curvature of the drill anchor tubes advantageously increases the “root effect” and thus the foothold of the foundation elements 5. In addition, it is feasible - as in the case of fracking - to produce cracks around the foundation elements 5 and to fill these with compressed concrete laitance, whereby a type of micro-root or hair root is produced which further increases the foothold of the foundation. However, all foundation elements 5 can basically be introduced and anchored into the ground 4 or on an imaginary horizontal plane in the region of the ground 4 in a vertical or inclined orientation with respect to the ground 4.

Figure 3 shows a plan view of the installing assembly 1 according to figure 2 as a sectional view through the supporting structure 2. In particular, the figure illustrates an ideally centred arrangement of the coupling structure 3 in the supporting structure 2 and its base surface 3a and its cover surface 2b within the lower end 2a of the supporting structure 2. The latticework- 1 ike design of the coupling structure 3 can also be seen, in particular the square design of the base surface 3a and the circular design of the cover surface 3b. In addition, the arrangement of the piles 3d is schematically illustrated, which piles are guided, starting from the circumferential region of the base surface 3a, in particular also from its corners 3c, in an inclined manner upwards to the cover surface 3b and thus form an outer contour of the coupling structure 3 which tapers upwards starting from the ground 4. Furthermore, the curing material 6 filling the supporting structure 2 is shown, which material is cast into the annular filling region 2c between the inner wall 2b of the supporting structure 2 and the sheet metal covering 3h of the coupling structure 3. Accordingly, the inner space 3g of the coupling structure 3 is free of the curing material 6 and can be entered e.g. via the cover surface 3b for mounting work.

Figure 4 illustrates a schematic detailed view of a first alternative installing assembly 1 which is braced with a supporting structure 2, formed as a monopile, via additional anchorings 7, each having a bracing element 7a formed as a steel cable, steel tube or steel rod or combinations thereof, in order to be able to absorb larger transverse forces. The bracing elements 7a are tensioned in each case between the supporting structure 2 and the associated additional anchoring 7. Typical adjusting members can be used for the tensioning process.

Moreover, in this alternative embodiment the coupling structure 3 widens conically starting from the base surface 3a to the cover surface 3b. This is advantageous because the curing material 6 is predominantly under pressure and the coupling structure 3 is under tension. Alternatively, the coupling structure 3 can also be cylindrical, buoy-shaped, in the shape of a hyperboloid of revolution or in the shape of a rhombus body.

As shown in figure 5 - a plan view of the installing assembly 1 according to figure 4 as a sectional view through the supporting structure 2 - for example three additional anchorings 7 can be arranged uniformly spaced apart from each other around the installing assembly 1 , e.g. the supporting structure 2, and anchored to the ground 4. The local arrangement of the additional anchorings 7 with respect to each other and around the supporting structure 2 can hereby be effected differently depending upon the occurring load distribution and the number of anchorings can also be varied. The additional anchorings 7 are formed like the previously described coupling structures 3 and are accordingly anchored in the ground 4 via foundation elements 5.

For the purposes of vibration damping, it is also feasible to provide a bracing or traction cable within the supporting structure 2, thus in the present case within the steel tube of the monopile, in order to achieve improved vibration damping. The bracing cable is hereby tensioned within the supporting structure 2 between the lower end 2a of the supporting structure 2 and an upper end of the tower 8c or a pod 8b of the OWT arranged thereon. At the lower end 2a, the bracing cable can be secured to the coupling structure 3 or a foundation element 5 formed e.g. as a middle anchor.

Figure 6 shows a schematic detailed view of a second alternative assembly 1 for installing the OWT according to figure 1 with a releasable mechanical connection between the supporting structure 2 and the coupling structure 3 in order to be able to place the supporting structure 2 together with the coupling structure 3 on the ground 4. The releasable mechanical connection is formed as a clamping connection in the manner of a push button and for this purpose comprises on the outside, at the lower end 2a of the supporting structure 2, a circumferential ring 2d and a multiplicity, preferably four, latching elements 10 uniformly distributed over the circumference of the base surface 3a of the coupling structure 3. The latching elements 10 are typically web-like and outwardly resilient, are oriented with their longitudinal extension in the longitudinal direction of the supporting structure 2 and have an inwardly directed, double wedge-shaped protrusion 10a in order to hold the ring 2d in the latched position and correspondingly release same by the cooperation of the wedge-shaped protrusions 10a and the resilient webs 10b when bringing together and releasing the supporting structure 2 and the coupling structure 3.

Figure 7 shows a plan view of figure 6, in which the uniform distribution of the four latching elements 10 over the circumference of the base surface 3a of the coupling structure 3 can be seen. A circumferential receiving ring 11 can also be seen between the latching elements 10, which ring is arranged on the base surface 3a of the coupling structure 3 and receives the ring 2d of the supporting structure 2. The latching elements 10 extend upwards from the receiving ring 11.

The previously described installing assembly 1 can be mounted in two particularly advantageous ways.

In a first variant, the supporting structure 2 - e.g. a monopile - with its lower end 2a and the coupling structure 3 formed as a grid structure are slid inside each other such that the coupling structure 3 with its previously described latticework design is arranged within the lower end 2a of the supporting structure 2 in the manner of a so-called inner jacket. Preferably, the supporting structure 2 is for this purpose lowered onto or over the coupling structure 3 placed on the floor. The coupling structure 3 or the piles 3d provided therefor form receptacles or guides for the foundation elements 5 and are fitted therewith prior to or after assembling the supporting structure 2. Then, a connection suitable for transporting by ship is established between the coupling structure 3 and the supporting structure 2 e.g. by means of a releasable mechanical connection such as for example via a screw connection or a wedge, clamp, bayonet or bolt connection, and the connection is brought to the intended destination. There, the supporting structure 2 with the coupling structure 3 is placed on the ground 4 and the coupling structure 3 is anchored in or to the ground 4 via the foundation elements 5.

Then, the connection between the coupling structure 3 and the supporting structure 2 is released in order to be able to orient the supporting structure 2. In a last step, by filling the inside of the supporting structure 2 with the concrete mixture 6 the coupling structure 3 is fixed with the supporting structure 2 in the desired orientation by the produced grout connection. If the coupling structure 3 is provided with a sheet metal covering 3h, the filling region 2c formed between the inner wall 2b of the supporting structure 2 and the sheet metal covering 3h is accordingly filled with the curing material 6, and so the grid structure of the coupling structure 3 located therein has curing material 6 flowing around it.

Arranging the foundation elements 5 in the coupling structure 3 or the piles 3d thereof can be effected above water on land or even on board a transport ship. However, it is also possible to seal the supporting structure 2 or at least the inner space 3g of the coupling structure 3 after it is lowered to the seabed 4 and to pump out the water located therein so that a type of water-free tunnel is formed therein. Only then is the coupling structure 3, in particular the guides or receptacles formed e.g. by the piles 3d, fitted with the foundation elements 5 on the ground 4 from the dry inner space 3g and subsequently the coupling structure 3 is anchored. The elements of a foundation element 5 formed as a drilled hole anchor or injection piles, which elements are typically modular in design and assembled during the drilling process, can be already previously welded, e.g. on board a transport ship, and brought to the coupling structure 3 at the desired length. It is likewise possible to use prefabricated drilling rods as foundation elements 5 which can be perforated in the area surrounding the drilling path for the ejection of the correspondingly used curing material 6. The use of drilled hole anchors with rolled-on worm, welding beads or corrugations is also feasible. Likewise, the aforementioned foundation elements 5 can be used in combination.

In a second variant, initially the coupling structure 3 is fitted with foundation elements 5, wherein these are arranged in particular in its piles 3d used as a receptacle or guide. Then, the coupling structure 3 is sunk to the ground 4 and there, as described above, anchored via the foundation elements 5. Of course, it is also possible to seal a coupling structure 3 provided e.g. by means of the sheet metal covering 3h, and to dry-pump it on the ground 4 in order only there to arrange the foundation elements 5 in the corresponding receptacles or guides of the coupling structure 3. Lowering and subsequent anchoring of the coupling structure 3 to the ground 4 are possible largely irrespective of the weather. When the weather conditions are sufficiently good, the supporting structure 2 can then be transported by ship and lowered. The coupling structure 3 is hereby used as a type of guiding spike and thus facilitates the sliding of the lower end 2a of the supporting structure 2 on or over the coupling structure 3. The coupling structure 3 extending from the ground 4 upwards in the direction of the water level W is thus threaded or inserted into the lower end 2a of the supporting structure 2. In a last step, the supporting structure 2 placed on the ground is oriented and the supporting structure 2 or the filling region 2c is filled with the concrete mixture 6 in order to establish the grout connection with the coupling structure 3.

After installing the installing assembly 1, in particular after establishing the grout connection between the coupling structure 3 and the supporting structure 2, the additional anchorings 7 illustrated in figures 4 and 5 and anchored to the ground 4 can be connected to the supporting structure 2 via the bracing elements 7a.

The previously described exemplified embodiment forms the supporting structure 2 preferably as a monopile. Of course, it is possible to secure other supporting structures 2 such as e.g. tripods, quadropods, tripiles or jackets, so long as these have tubular legs or supports open towards the ground 4, to the ground 4 in a corresponding manner via the coupling structure 3 in accordance with the invention. It is also possible to use corresponding installing assemblies 1 not only in the open sea near to a coast but also in large lakes or inland seas. Basically, it is also possible to drive the foundation elements 5 into the ground 4.

List of reference signs

1 installing assembly

2 supporting structure 2a lower end

2b inner wall 2c filling region 2d ring

3 coupling structure 3a base surface

3b cover surface 3c corner 3d pile

3e horizontal strut 3f diagonal strut 3g inner space 3h sheet metal covering

4 ground

5 foundation element 6 curing material

7 additional anchoring 7a bracing element

8 above-surface structure 8a rotor 8b pod 8c tower

9 water

10 latching elements 10a protrusion 10b web

11 receiving ring W water level

Claims

1. Assembly (1) for installing an above-surface structure (8) in water-covered ground, in particular for the monopile-installation of an offshore wind turbine, having at least one coupling structure (3) resting on a ground (4) which can be anchored to the ground (4) via at least one foundation element (5) and to which a supporting structure (2) can be secured for supporting the above-surface structure (8), characterised in that the at least one coupling structure (3) is arranged within the supporting structure (2), in particular within a lower end (2a) of the supporting structure (2).

2. Assembly (1) as claimed in claim 1, characterised in that the coupling structure (3) is formed as a grid structure, in particular with a Vierendeel, framework or latticework design.

3. Assembly (1) as claimed in claim 1 or 2, characterised in that the coupling structure (3) has, starting from the ground (4), an upwardly tapering or widening extent or a barrel shape.

4. Assembly (1) as claimed in any one of claims 1 to 3, characterised in that the coupling structure (3) for the at least one foundation element (5) forms a guide in which the at least one foundation element (5) can be received prior to anchoring to the ground (4).

5. Assembly (1) as claimed in any one of claims 1 to 4, characterised in that the at least one foundation element (5) can be anchored to the ground (4) by means of drilling or vibrating.

6. Assembly (1) as claimed in any one of claims 1 to 5, characterised in that the supporting structure (2) can be secured to the coupling structure (3) via a curing material (6), in particular a concrete mixture, which is introduced into the supporting structure (2), or a mechanical clamp.

7. Assembly (1) as claimed in claim 6, characterised in that regions of the supporting structure (2) or of the coupling structure (3) contacted by the curing material (6) have a compound-reinforcing, preferably fluted, surface structure.

8. Assembly (1) as claimed in claim 6 or 7, characterised in that a sheet metal covering (3h) is arranged on or within the coupling structure (3), wherein a filling region (2c) for the curing material (6) which encloses the coupling structure (3) is formed between the sheet metal covering (3h) and an inner wall (2b) of the supporting structure (2).

9. Assembly (1) as claimed in claim 8, characterised in that the filling region (2c) is annular and widens or tapers upwards, starting from the ground (4).

10. Assembly (1) as claimed in any one of claims 1 to 9, characterised in that the supporting structure (2) is braced via at least one outer additional anchoring (7), each having a bracing element (7a).

11. Assembly (1 ) as claimed in claim 10, characterised in that the at least one additional anchoring (7) is formed in the form of a coupling structure (3) and is anchored to the ground (4) via foundation elements (5).

12. Method for mounting an assembly (1) as claimed in any one of claims 1 to 11 on water- covered ground (4), characterised in that in a first mounting step a coupling structure (3) is arranged and secured within a supporting structure (2) above water, in a second mounting step at least one foundation element (5) is arranged in the coupling structure (3) for anchoring the coupling structure (3) to the ground

(4), in a third mounting step the supporting structure (2) is lowered with the coupling structure (3) to the ground (4) and the coupling structure (3) is anchored to the ground (4) via the at least one foundation element (5), in a fourth mounting step the supporting structure (2) is oriented, and in a fifth mounting step the supporting structure (2) is secured to the coupling structure (3).

13. Method as claimed in claim 12, characterised in that in the first mounting step the coupling structure (3) is releasably secured within a supporting structure (2), in the fourth mounting step the coupling structure (3) is released from the supporting structure (2) and the supporting structure (2) is oriented with respect to the coupling structure (3).

14. Method as claimed in claim 12, characterised in that in the fourth mounting step the coupling structure (3) is released from the supporting structure (2) and the supporting structure (2) is oriented with the coupling structure (3) by securing the foundation elements

(5) to the coupling structure (3).

15. Method as claimed in any one of claims 12 to 14, characterised in that the second mounting step occurs whilst above water or only after the lowering and subsequent dry pumping of the coupling structure (3) on the ground (4).

16. Method for mounting an assembly (1) as claimed in any one of claims 1 to 11 on water- covered ground (4), characterised in that in a first mounting step at least one foundation element (5) is arranged in the coupling structure (3) for anchoring the coupling structure (3) to the ground (4), in a second mounting step the coupling structure (3) lowered to the ground (4) is anchored to the ground (4) via the at least one foundation element (5), in a third mounting step, the supporting structure (2) is lowered to the ground (4) and a lower end (2a) is placed over the coupling structure (3), whereby the coupling structure (3) is arranged within the supporting structure (2), in a fourth mounting step the supporting structure (2) is oriented with respect to the coupling structure (3) and in a fifth mounting step the supporting structure (2) is secured to the coupling structure (3).

17. Method as claimed in claim 16, characterised in that the first mounting step occurs whilst above water or only after the lowering and subsequent dry-pumping of the coupling structure (3) on the ground (4).

18. Method as claimed in any one of claims 12 to 17, characterised in that the supporting structure (2) is secured to the coupling structure (3) by filling the supporting structure (2) with a curing material (6) or by mechanical clamping.