A platform based on several individual ground piles connected together

Abstract

The invention relates to a platform founded on several interconnected individual base piles (2), with a connecting sleeve (4) for connection to a respective individual base pile (2) and with an operating structure which has several projections on its underside for fixing in a recess on a support element (3). The support element (3) has several hollow body-shaped base elements which form a ring-shaped, closed, polygonal structure with a central recess. As a result of the weight of the operating structure (5) and external load effects, a force flow occurs from the operating structure (5) into the support element (3) and from there into the individual base piles (2), which, depending on the type of connection, can have a reinforcing effect on the connection between the support element (3) and the individual base piles (2) connected to it.

Description

[0001] The invention relates to a platform founded on several interconnected individual base piles, also referred to as monopiles, in particular designed as an offshore transformer or converter platform, in which the individual base piles are driven into the seabed and are connected by means of a connecting sleeve system, comprising at least one connecting sleeve and one supporting element, to accommodate the functional operating structure, also referred to as topside.

[0002] The operational structure foundations, founded on a single single base pile, consist of a central single base pile driven into the seabed and a connecting sleeve placed on top. The connecting sleeve also serves to compensate for misalignments that may occur during the driving of the single base pile. The gap of approximately 50 mm to 150 mm between the connecting sleeve and the single base pile is filled with high-strength concrete, thereby creating a pipe-in-pipe connection, also known as a grouted connection. Such foundations offer the advantage of being relatively quick to install and requiring little preparatory work on the seabed. Alternatively, the connection can be created using a ring flange connection or a steel slip joint. Another advantage is the low maintenance requirements after installation.

[0003] The expansion of offshore wind energy requires substation platforms or converter platforms. On these substation platforms, the electricity generated by individual wind turbines is transformed and transmitted to land via a submarine cable.

[0004] Most offshore platforms currently consist of an operating structure, a supporting structure comprising a truss (jacket), and a ground pile foundation. However, the jacket's deadweight has increased to such an extent that it is very difficult to handle during transport and installation. Furthermore, such foundation structures have large attack surfaces for wave systems and therefore generate high loads due to their design.

[0005] During assembly, the foundation piles of the offshore platform are first driven into the seabed, and then the platform upper section is placed on the foundation piles, which are circular in cross-section and have an upper edge. It is also already known to provide a damping device with a so-called Leg Mating Unit (LMU) at the upper edge.

[0006] A substation platform according to EP 3 530 814 B1 uses a piling rig supported on the seabed by extendable support legs. The foundation piles are each guided through a dedicated piling template on the substation platform, so that the supports on the underside of the platform's upper section rest precisely on the ends of the foundation piles, and the platform's upper section forms the only structural connection between the foundation piles.

[0007] EP 3 670 752 A1 relates to an offshore platform having at least one base pile with a support arranged on the inner wall, which is shaped as a circumferential, annular flange such that a damping device rests on the flange. The upper part of the platform has a support leg stump for each base pile and each damping device, which rests in the receptacle so that the support leg stumps support the entire weight directly on the base pile. First, several base piles are driven and their horizontal positions, in particular their relative positions to one another, are determined. Then, the respective damping device is placed with its pipe section on the flange and the pipe sections are shortened longitudinally such that the receptacles of the damping devices of the various support legs, facing away from the seabed, are at the same distance above the sea surface.

[0008] Furthermore, DE 10 2018 104 328 A1 describes the foundation of a transfer platform in which several base piles are driven into the seabed and a sleeve is placed over each of the base piles. Adjacent sleeves are connected to each other by a fixed rod system. A platform upper section is moved over the upper offshore ends of the base piles above the support pieces of the associated sleeves and then rests on the base piles.

[0009] The invention is based on the object of creating a simple way to improve the load-bearing capacity, in particular the rigidity of the platform. At the same time, the assembly of the platform should be improved.

[0010] This object is achieved according to the invention with a platform according to the features of claim 1. The further embodiment of the invention can be found in the subclaims.

[0011] According to the invention, a platform is provided with a support element which is particularly polygonal in its basic shape and which is equipped with at least one connecting sleeve for a respective individual base pile in several corner regions and with several receptacles which have at least one recess for each projection of the supports of the operating structure, wherein the receptacles are arranged on the support element in such a way that the force flow as a result of a load effect, in particular the weight of the operating structure and dynamic environmental influences, acts on the support element and is transferred by means of the support element to the connecting sleeve and distributed into the individual base piles.According to the invention, on the one hand, the supporting element is loaded by the weight of the operating structure and, on the other hand, the acting force is transferred through the operating structure to the various individual base piles via the respective connecting sleeve. This allows a previously unattainable rigidity and thus load-bearing capacity of the platform to be achieved. Due to the acting force, the supporting element braces the individual base piles against each other and fixes them in their respective position and orientation. At the same time, load balancing occurs with a uniform force introduction into the various individual base piles. By orienting the connecting sleeves of the individual base piles transverse to the main extension plane of the supporting element, the weight leads to an improved stiffening against acting transverse forces, which can thus be reliably absorbed by the structure.It has been shown that the unavoidable, non-parallel orientation of the individual base piles, which is unavoidable in practice, results in improved mutual support. The flexibility of the individual base piles allows for easy compensation of this unavoidable, non-parallel orientation, compared to significantly stiffer truss structures (jackets). By optimizing the load-bearing element as part of a connecting sleeve system, the installation tolerances of the individual base piles can be easily compensated within a certain range.

[0012] A particularly advantageous embodiment of the invention is also achieved in that the support element has an at least substantially flat upper support belt surface and a lower support belt surface that is substantially parallel thereto, so that the resulting multiple clamping of the connecting sleeves in the basic structure of the support element, which in this case is cuboid, for example, results in a significant improvement in the rigidity of the platform, which can be easily adapted to different conditions, in particular loads, by appropriately dimensioning the distance between the horizontal upper support belt surface and the lower support belt surface. This also makes it possible to implement a modular concept in which, for example, three or more parallel support belt surfaces can be connected to one another in order to further increase strength.Furthermore, the carrying belt surfaces can be designed to be congruent or identical, at least in their basic shape, in order to simplify the manufacturing process.

[0013] It is particularly expedient if the connecting sleeves are connected at least to the upper and lower chord surfaces, with the connecting sleeves preferably penetrating at least the lower chord surface. Of course, the connecting sleeves can also be connected to other chord surfaces that may be present. This creates additional connection points that increase the strength of the structure.

[0014] Another, equally particularly practical embodiment of the invention is also achieved by designing the support element, at least in sections, as a hollow body, thus achieving high flexural rigidity and torsional strength in its construction. Furthermore, this allows the support element to achieve sufficient buoyancy and thus floatability in a not completely flooded state, which allows for easy transport by towing. Of course, the support element can also accommodate functional elements, such as cabling, piping, air conditioning, or other connections, inside.

[0015] According to another particularly advantageous embodiment of the invention, the support element is constructed from several hollow body-shaped base elements with a polygonal cross-section arranged in a common plane, with adjacent base elements enclosing an angle between 60° and 120°. The base elements form, for example, rectangular cross-sections that can be easily adapted to different requirements, particularly by changing the cross-sectional dimensions and lengths. Furthermore, the base elements can be universally prefabricated and already equipped with the usual connecting elements, in particular cabling and fixing elements.

[0016] It has already been shown that an advantageous variant in which the support element comprises several basic elements connected in a closed ring arrangement leads to optimal results, although additional bracing, for example, diagonal bracing, is of course not excluded. The ring shape of the support element also produces good results for soil conditions where there is no lateral support in the soil layers near the seabed.

[0017] Another, equally promising embodiment of the invention is also achieved by equipping at least some of the receptacles with a pre-installed damping device, which can be implemented, for example, as part of a Leg Mating Unit (LMU). The damping device is designed to lower the operating structure onto the support element by damping loads occurring during positioning and preventing potential damage. After lowering the projection into the receptacle equipped with the damping device, a preferably pourable or flowable pressure transmission medium is discharged until direct contact is established between the projection and the cylindrical wall of the recess.

[0018] Advantageous variants of the invention can be implemented in which the number of receptacles for the projections of the operating structure and the number of individual base piles differ from one another or are arranged at a distance on the support element transversely to their respective main axes. In this case, multiple recesses can also be provided for alternative use. However, a variant of the invention is also particularly advantageous in which the recess of each receptacle is arranged at least substantially coaxially with one of the connecting sleeves, thus avoiding undesirable tilting or bending moments, particularly in the event of a one-sided load acting during assembly.

[0019] A further particularly practical development of the invention is also achieved if the support element has pre-installed connection elements, in particular connection cables, in particular within an interior space defined in the support element, in order to enable in particular a problem-free electrical installation of the preferred transformer or converter platform through the support element.

[0020] A further, equally practical modification of the present invention is also realized by equipping the connecting sleeve with a cable pull-in aid that can be used, in particular, along a guide in different positions on a cable platform. For this purpose, a cable platform known as a cable hang-off platform is arranged concentrically to the connecting sleeve in the connecting sleeve, allowing multiple submarine cables to be secured in a circular arrangement. The cable pull-in aid, designed, for example, as a cable winch, enables circumferential use via a circular guide, such as a rail guide or a suspension.

[0021] The submarine cables exit at the bottom through a respective opening in the circumferential surface of the individual ground pile. The openings are evenly distributed, particularly around the perimeter, and arranged at different heights relative to the ground to ensure sufficient spacing between the submarine cables. This ensures a helical routing of the submarine cables between the opening and the cable platform, particularly through the use of additional retaining devices.

[0022] Preferably, several supporting elements can be combined as a substructure of the operating structure in different relative positions to each other, whereby a direct connection of adjacent supporting elements is not necessary, so that the force connection can take place exclusively via the operating structure.

[0023] The invention permits various embodiments. To further clarify its basic principle, one of them is illustrated in the drawing and described below.

[0024] This shows in Fig. 1 is an exploded view of a platform according to the invention with an operating structure, supporting elements and several individual base piles; Fig. 2 is a perspective view of the Figure 1 shown platform; Fig. 3 a perspective view of the Figure 1 shown support element with connecting sleeves; Fig. 4 an enlarged perspective view of the connecting sleeve; Fig. 5 a further perspective view of the connecting sleeve; Fig. 6 a schematic diagram of the cable routing within a single base pile; Fig. 7 a plan view of a cable platform for cable routing.

[0025] A platform 1 according to the invention in an embodiment as a transformer platform with a grouted connection is described below with reference to the Figures 1 to 7 described in more detail. As particularly in the Figures 1 and 2 As can be seen, the platform 1 comprises a total of eight individual ground piles 2 driven into the ground, with four individual ground piles 2 being firmly connected by a common support element 3. For this purpose, the respective support element 3 has a corresponding number of connecting sleeves 4 for fixing the individual ground piles 2, which are also referred to as transition pieces and are designed as a pipe-in-pipe connection for fixing each individual ground pile 2.

[0026] In a conventional manner, the connecting sleeves 4 on the support element 3 also serve to correct the position. The connecting sleeve 4 has an oversize compared to the individual base pile 2 to be fixed, and the annular gap between the connecting sleeve 4 and the individual base pile 2 accommodated therein allows for limited inclination compensation, deviating from a coaxial orientation, if necessary. The set relative position is permanently fixed by a pressure-resistant filling compound.

[0027] The operating structure 5, also referred to as the topside, is mounted on the two support elements 3. For this purpose, the operating structure 5 has several supports (not shown), each with a downward-facing projection, which serves to fix the operating structure 5 to the corresponding support element 3 in a force-fitting and form-fitting manner.

[0028] The support element 3 has a polygonal basic shape and is designed, at least in sections, as a hollow body with a largely flat upper support chord surface 6 and a lower support chord surface 7 running parallel thereto, to which the connecting sleeves 4 are permanently connected. The support chord surfaces 6, 7 are formed by four cuboid base elements 8 with a rectangular cross-section arranged in a common plane and connected at a right angle. Different polygonal arrangements for a different number of individual base piles 2 can be realized as required. The base elements 8 thus form a ring-shaped, closed structure with a central opening.

[0029] As in the Figures 3 to 5As can be seen, a plurality of recesses 9 for the projections (not shown) of the operating structure 5 are arranged coaxially to the connecting sleeves 4 on the support element 3. An essential aspect of the invention is that the flow of forces resulting primarily from the weight of the operating structure 5 but also from dynamic external load effects is introduced from the operating structure 5 into the support element 3. Depending on the type of connection, this load effect can have a reinforcing effect on the connection between the support element 3 and the individual base piles 2 connected to it, in particular in the transition area of ​​the pipe-in-pipe connection of the connecting sleeves 4, and is further promoted by the respective angular compensation between the connecting sleeve 4 and the individual base pile 2.

[0030] Unlike the prior art, the axial preferential load-bearing effect of the connection and individual base piles is used to transfer the load of the operating structure, resulting in savings or increased capacity. Furthermore, changing loads, in particular load changes in the force transmitted from the operating structure 5 to the supporting element 3, do not result in a resulting, undesirable one-sided or asymmetrical force acting on the individual base piles 2, thus also precluding any change in the relative position of the individual base piles 2 during use of the platform 1, for example, due to inclination or settlement.

[0031] According to the invention, a rigid support element 3 is achieved for the first time in combination with a tolerance-capable connection to the individual base piles 2 and the possibility of accommodating pre-installed means for tolerance compensation, for example by hydraulic rams, in which at the same time extensive pre-equipment with secondary steel (access systems, corrosion protection) and integrated cabling (pre-equipment) within the structure is achieved.

[0032] In the illustrated embodiment of the invention, the recesses 9 are additionally equipped with a damping device 10, also referred to as a leg mating unit (LMU). The damping device 10 is designed to reduce the load peaks that occur when the operating structure 5 is lowered onto the support element 3 and to prevent possible damage. For this purpose, a chamber 11 of the recess 9 contains a pourable or flowable pressure transmission medium (not shown in detail), which is slowly drained from the chamber 11 until the end position of the projections in the respective recess 9 is reached.

[0033] In addition, the damping device 10 can also be equipped with friction-reducing cushions, such as Teflon pads, for simplified installation using the conventional float-over and lifting assembly technique. Two superimposed work platforms 18 serve for cable termination.

[0034] In the Figures 6 and 7 A cable platform 12 for a plurality of submarine cables 13 is shown, which are led out through several openings 14 distributed at different heights along the circumference of the individual ground pile 2 in the area near the ground of the individual ground pile 2. For the feeding and installation of the submarine cables 13, the cable platform 12 is equipped with a cable pulling aid 15, which can be moved along a circular guide 16 designed as a rail into different positions according to the predetermined arrangement of the respective submarine cable 13. Furthermore, compensation points 17 serve to compensate for height differences during installation before grouting or concreting. LIST OF REFERENCE SYMBOLS

[0035] 1Platform 2Single base pile 3Support element 4Connecting sleeve 5Operational structure 6Supporting belt surface 7Supporting belt surface 8Base element 9Recess 10Damping device 11Chamber 12Cable platform 13Submarine cable 14Opening 15Cable retraction aid 16Guide 17Compensation point 18Working platform

Claims

1. A platform (1) connected to at least three individual base piles (2), in particular designed as a transformer or converter platform, with a plurality of connecting sleeves (4) for connecting a respective individual base pile (2) to the platform (1), an operating structure (5) and a plurality of supports, each having a projection, on the underside of the operating structure (5), characterized bya support element (3) which is particularly polygonal in its basic shape and which is equipped, in particular in corner regions, with at least one connecting sleeve (4) for a respective individual base pile (2) and with a plurality of receptacles having a recess (9) for each projection of the supports of the operating structure (5), wherein the receptacles are arranged on the support element (3) in such a way that the force flow as a result of the load effect of the operating structure (5) and / or external force effects acts on the support element (3) and is transferred by means of the support element (3) to the connecting sleeve (4) and introduced into the individual base piles (2).

2. Platform (1) according to claim 1, characterized in that the support element (3) has an at least substantially flat upper support belt surface (6) and a substantially parallel lower support belt surface (7) connected by webs.

3. Platform (1) according to claim 1 or 2, characterized in thatthe connecting sleeve (4) is connected at least to the upper carrying belt surface (6) and the lower carrying belt surface (7).

4. Platform (1) according to at least one of the preceding claims, characterized in that the support element (3) is designed at least in sections as a hollow body.

5. Platform (1) according to at least one of the preceding claims, characterized in that the support element (3) has several basic elements (8) connected in a ring-shaped closed arrangement.

6. Platform (1) according to claim 5, characterized in that several basic elements (8) are arranged in a common plane and have a polygonal cross-sectional shape.

7. Platform (1) according to at least one of the preceding claims, characterized in that the receptacles are equipped with a damping device (10).

8. Platform (1) according to at least one of the preceding claims, characterized in thatthe recesses (9) of the receptacles are arranged at least substantially coaxially to a respective connecting sleeve (4).

9. Platform (1) according to at least one of the preceding claims, characterized in that the support element (3) has pre-installed connecting elements, in particular connecting cables, in particular within an interior space defined between the outer support belt surfaces (6, 7).

10. Platform (1) according to at least one of the preceding claims, characterized in that the connecting sleeve (4) is equipped with a cable pulling aid (15) which can be used in particular along a guide (16) in different positions on a cable platform (12).

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