Removable heavy-duty support element for monopiles and ship hulls

Abstract

Reconstructible heavy-duty support element (10) for monopiles (2) and ship hulls, at least comprising: - a geotextile container with a cover (11), - a filling of a compacted, fine-grained bulk material placed into the interior enclosed by the shell (11); - several horizontally installed, grid-shaped reinforcement elements (13, 13.1, ...,13.6) which are placed in the installed filling in several spaced-apart intermediate layers (14.1,...14.6) and which cover at least 90% of the cross-section enclosed by the shell.

Description

[0001] The invention relates to a reversible heavy-duty support element for monopiles and ship hulls.

[0002] Offshore wind turbines utilize so-called monopiles, tower structures made of steel tubes weighing up to 1,500 tons. These monopiles must be temporarily stored until further processing or transport by ship. Currently, they are placed on steel supports and secured against rolling with wedges. Depending on the weight and length of the steel tubes, two to eight supports are required. These steel elements are very expensive to manufacture and monitor. The minimum support height for the supports is approximately 1.5 meters to ensure safe passage for a low-loader vehicle. With conically shaped tubes, storage in the conical area is severely limited using existing methods.

[0003] In shipbuilding, ships and hulls are supported in docks or on land. For this purpose, they are placed with their keel line onto a series of so-called keel blocks. On either side, the hull is supported by another row of so-called bilge blocks. Blocks also represent heavy-duty support elements, which in large shipbuilding projects are often formed from a series of concrete blocks that are either fixed in place and cannot be moved at all, or which can only be moved with correspondingly powerful lifting equipment.

[0004] In both described applications, one of the requirements for the heavy-duty support elements is high compressive strength. Furthermore, in both cases, spherically curved bodies must be supported. However, flat surfaces of concrete blocks or edges of steel frames lead to unfavorable line or even point loading of the applied loads; a surface distribution of the weight forces is not possible.

[0005] US Patent 4,501,401 A describes a camera support cushion. Even with appropriate scaling, the cushion cannot support heavy loads. To position a camera, it is only necessary to manually deform the cushion to create a stable support that holds the camera during the photograph. The vertical chamber walls serve to prevent or at least significantly reduce the displacement of the filling material between the chambers within the container. However, they are not designed to withstand high compressive stresses acting on the outer surface. The vertical partitions also cannot withstand the compressive stresses that arise in a highly compressed filling. If such a support cushion were subjected to a heavy load, it would inevitably burst open around the outer circumference, either at the seam or within the fabric itself.The camera support cushion is also unsuitable for outdoor use. The object of the present invention is therefore the development of a reusable, heavy-duty support element with high load-bearing capacity, which is cost-effective to manufacture and also dismantle, and which, in addition to high compressive strength, allows adaptation to the contour of the applied load.

[0006] This problem is solved by a reversible heavy-duty support element for monopiles and ship hulls with the features of claim 1.

[0007] The container of the heavy-duty support element, preferably made of geotextiles, is very lightweight and requires virtually no storage space. It is highly load-bearing and can be filled with locally available bulk material. Once manufactured, a heavy-duty support element can be moved, at least within its storage area.

[0008] When it is no longer needed, dismantling is remarkably simple: The textile outer shell is cut open so that the filling can trickle out or be washed out with water. In the context of the present invention, "removable" therefore means that the heavy-duty support element can be removed with simple tools, if not manually, without forming massive structures that can only be removed by heavy jackhammers or explosives.

[0009] The casing can also be made of materials other than geotextiles, which are easy to handle and transport and are capable of absorbing the tensile stresses that occur during the installation of the infill within the casing. For example, a plastic pipe can also be used because, in the finished heavy-duty support element, very few forces resulting from the applied load are transferred into the casing.

[0010] However, geotextiles are preferred as containers, as they offer the advantage, in addition to the properties already mentioned above, of allowing for various diameters and shapes to be achieved by sewing a strip to the desired circumference or by sewing several pieces together, including polygonal cross-sections. Furthermore, good moisture regulation is possible through the fabric. A base section of the container directly connected to the outer shell is advantageous in terms of handling, transport, and drainage.

[0011] Depending on the number of layers with appropriate intermediate layers installed, the height can be adjusted to local requirements, allowing even conical monopile shapes to be supported. For ship hulls, simple adaptation to the keel line is possible.

[0012] The bulk material must be such in terms of grain size and shape that a dense solid packing is achieved during installation and, if necessary, during subsequent compaction after the load is applied, thus preventing flow under load. Therefore, a lightweight, shear-resistant aggregate with sufficient grain stability is required.

[0013] For the purposes of the present invention, fine-grained materials are already bulk materials such as sand with a grain size of 1 to 2 mm.

[0014] The use of hard coal boiler ash (HBA) is advantageous, as it is available at low cost as an industrial by-product and meets the following requirements: - low weight when installed, - high shear strength - and sufficient grain stability.

[0015] Typical characteristics of this filler are: Grain size distribution GU according to DIN 18196 100% Proctor density 1,20...1,30 Mg / m 3 Optimal water content 25...30 % Friction angle φ 39° Cohesion c / c u 0 / 0 kN / m 2 Stiffness modulus E s 100 MN / m 2

[0016] The geotextile shell possesses high tensile strength, enabling it to reliably absorb radial forces resulting from the earth pressure exerted on the load-bearing infill. However, since the loads are primarily transferred by the reinforced infill within the heavy-duty support element according to the invention, the shell essentially serves an additional securing and supporting function. Furthermore, it prevents the infill material from leaking out, thus ensuring the transportability of the entire element.

[0017] If, according to a preferred embodiment of the invention, coal boiler ash is used as bulk material, the geosynthetics used in contact with the ash must be resistant to alkaline conditions, since the ash has pH values ​​> 10. The casing of the heavy-duty support element therefore preferably consists of a coated, alkali-resistant PVA fabric. The casing is delivered to the construction site fully sewn. The coating ensures sufficient UV resistance for a service life of at least 10 years and also guarantees the necessary robustness of the element.

[0018] A key feature of the heavy-duty support element according to the invention is the horizontal reinforcement layers integrated into the infill. These create an intensive frictional bond between the reinforcement and the unbound material, preferably by using geogrid sections as intermediate layers, which offer open, friction-enhancing structures. However, the use of steel mesh mats is also possible.

[0019] The advantages of the invention are already achieved by means of reinforcement layers loosely inserted into the cross-section of the shell. However, it is also possible to establish a connection between the reinforcement layers and the shell. This has the particular advantage that the heights for the reinforcement layers can be predetermined directly on the wall of the shell and no longer need to be measured during installation.

[0020] Preferably, reinforcement is applied in layers with the horizontal reinforcement elements at a vertical distance of approximately 30 cm.

[0021] Preferably, a biaxial geogrid made of PVA is used. It is cut to a specific diameter adapted to the diameter of the shell and installed without a tensile bond to the shell.

[0022] The empty shell is preferably provided on a transport platform so that the finished heavy-duty support element is easier to transport and does not have to be disassembled by removing the bulk material each time it is moved. A steel plate with welded-on U-profiles can be used as the transport platform, providing a forklift loading point. Pressure-resistant insulating panels can be added to compensate for height differences between the profiles.

[0023] Another solution to the problem according to the invention is provided by a method for manufacturing a recyclable heavy-duty support element with the features of claim 12. Example of Procedure A

[0024] The method for manufacturing a heavy-duty support element according to the invention preferably involves the steps described below: - An empty container, consisting of a base and outer shell, is delivered fully sewn. The required number of geogrid discs and any necessary cover layer made of non-woven fabric are also included. - The empty shell is placed in a frame, possibly on a transport plate, and secured against being pulled down during filling. Filling can be carried out hydraulically or mechanically. In the case of mechanical filling, the fill material must be moistened and the moisture content adjusted to approximately 90% of the optimal moisture content. In the case of hydraulic filling, a drainage mat must be installed inside and beneath the shell and also secured during the filling process. Alternatively, a different type of drainage system can be used. - Filling always begins with the insertion of an initial layer at least 15 cm thick and its compaction. When using SKA as bulk material, this layer and all subsequent layers are compacted to at least 95% of Proctor density. The geogrids are then laid smoothly and without creases, starting with the bottom layer on the first SKA layer, at a distance of ≤ 30 cm from each other. The subsequent fill layer should be installed from the center outwards. - The upper layer consists of another layer of loose material with at least half the height of the aforementioned distance of the intermediate layer, for example a layer of at least 15 cm at the top, on which a thick nonwoven fabric can be placed.

[0025] The described preferred measures according to the invention, in particular with regard to the selection and installation of the filling, result in the loads being predominantly carried away via the fill and the reinforcement installed therein, and the earth pressure that still acts on the shell at the edge is reduced to such an extent that even under very high loads the tensile forces in the shell remain below the tensile strength of the fabric.

[0026] The heavy-duty support element according to the invention has a compact shape, meaning it is much wider than it is tall. The ratio of diameter to height is, in particular, significantly less than 0.5, so that there is no risk of buckling.

[0027] When calculating the required number of layers, the compaction and settlement behavior of the fill must be taken into account, which can reduce the installation height of the fill by up to 10%.

[0028] To enable the heavy-duty support element to be moved within the storage area, it is preferably mounted on a transport pallet so that it can be lifted and moved with a forklift. The transport pallet should be made of a load-bearing, rigid material such as steel or fiberglass and should have integrated hollow profiles to allow for handling by forklift or similar equipment.

[0029] The reinforcement elements are preferably made from biaxial geogrid sections, which are lightweight and can be transported in a space-saving manner when rolled or folded. However, other reinforcement elements made of uniaxial or biaxial, prefabricated, dimensionally stable grids made of plastic, carbon, or steel can also be used. Example of procedure B:

[0030] On a stable foundation, two heavy-duty support elements, each 4 m in diameter and 1.60 m high, were erected according to the procedure described above. Coal boiler ash with the properties described above was used as the filler material. The filler material was hydraulically installed using a concrete pump. Additional mechanical compaction of each individual layer with a vibratory plate compactor achieved a compaction level of up to 92%.

[0031] After a one-day waiting period to allow the fill to drain, a steel pipe with a maximum outer diameter of 7 m and a weight of 1200 t was placed onto the two spaced-apart heavy-duty support elements. This resulted in a calculated load of 600 t per support point. Due to the deformability of the fill, which was further compacted by the application of the load, a large bearing surface was achieved. Unlike conventional line contact with concrete and timber elements, this full-surface support resulted in low surface pressure. Due to the corresponding settling behavior of the fill, with a bearing surface width of 1 m to 2 m and a length of approximately 4 m, a depression of 10 cm was observed below the pipe's centerline. After the load was removed, i.e., after the pipe was lifted from the heavy-duty support elements, the deformation decreased to 7 cm.

[0032] The invention is explained in more detail below with reference to the drawings. The figures show: Fig. 1 a bearing arrangement with a steel tube; Fig. 2 a heavy-duty support element in a schematic view from the front; Fig. 3 a heavy-duty support element on a transport pallet in front view and Fig. 4. A view of the transport pallet from below.

[0033] Fig. Figure 1 shows a bearing arrangement with two heavy-duty support elements 10 and a pipe 2 supported on them. The diameter of the pipe 2 is approximately equal to the diameter of the heavy-duty support elements 10. However, it can also be significantly larger. The diameter of the heavy-duty support elements 10, which are primarily round, is dimensioned such that a sufficiently wide bearing surface is formed for the curved pipe shell, reliably preventing the pipe 2 from rolling off.

[0034] In the illustrated embodiment, only two heavy-duty support elements 10 have been used to obtain defined load cases for a static verification of the heavy-duty support elements 10 according to the invention. For the permanent support of a pipe 2, a monopile, a ship's hull, or the like, a plurality of heavy-duty support elements 10 are arranged in series one behind the other to prevent deflection under the load as well as excessive individual loads on any single heavy-duty support element 10. The height of each individual heavy-duty support element 10 in the series can also be varied by using a different number of intermediate layers to adapt to the height distribution of the load.

[0035] Fig. Figure 2 shows the heavy-duty support element 10 in a schematic view, in which the filler material is not shown and an outer shell 11 is shown transparently.

[0036] The geotextile container, which forms the basis, initially comprises only the outer shell 11 and a base 12 attached to it, in particular sewn to it. The container can be easily transported by folding or rolling. At the designated storage location, it is suspended using a device (not shown) to facilitate the subsequent filling process. The base 12 of the container rests on a solid surface.

[0037] A first intermediate layer 14.1 of the fill material is then applied directly to the base 12 and continuously compacted until the desired height of the intermediate layer of 25 cm to 30 cm is reached. Subsequently, a geotextile mesh is placed on top of the previously installed intermediate layer 14.1 as a reinforcement element 13.1. The reinforcement element 13.1 absorbs the radial forces resulting from the compression of the fill material, preventing them from acting on the shell 11. The reinforcement elements 13.1 to 13.6 are loosely inserted and cover at least 90% of the base area of ​​the geotextile container. They can extend right up to the shell 11, but are not rigidly connected to it.

[0038] A further intermediate layer 14.2 is then applied and compacted again. The intermediate layer 14.2 is capped by another reinforcement element 13.2 designed as a geotextile grid.

[0039] The subsequent intermediate layers 14.3 to 14.6 and reinforcement elements 13.3 to 13.6 are installed in the same manner until the desired height of the heavy-duty support element 10, approximately 1.60 m to 1.80 m, is nearly reached. The height is chosen so that a transport vehicle for road transport can drive directly under the load, thus eliminating the need for crane repositioning.

[0040] Once the desired height is almost reached, a final top layer 15 is applied to the upper reinforcement element 13.6 formed by a geotextile grid and also compacted. A fleece layer or similar material can be laid on top for weather protection.

[0041] With the installation of the top layer 15, the heavy-duty support element 10 is completed. In the case of hydraulic installation of the fill, a settling period of at least one day is recommended. The water contained within can easily drain away due to the water permeability of the woven soil 12 and the casing 11, as well as the drainage elements preferably also provided in the base area.

[0042] In Fig.Figure 3 shows a heavy-duty support element 10 on a transport pallet 20. The geotextile container rests with its base 12 on a steel plate 21, beneath which, in the illustrated embodiment, two rectangular steel profiles are attached. These profiles serve as forklift pockets 22, allowing the heavy-duty support element 10, along with its contents, to be picked up and transported using a heavy-duty forklift. To reduce the deflection of the steel plate 21, suitable spacers 23 are inserted in the spaces next to the forklift pockets 22 and beneath the steel plate 21. These spacers can be pressure-resistant rigid plastic foam panels, concrete elements, or special geotextile elements.

[0043] Fig.Figure 4 shows the view of the heavy-duty support element 10 from the underside of the transport pallet. The two rectangular steel corner profiles, which form the forklift pockets 22, are held at a fixed distance from each other by crossbeams 24. The hatched areas represent the lining of the underside next to the steel profiles 23, 24, using suitable spacer elements 23. Only in the lower left area is a spacer element omitted in this illustration, so that the steel plate 21 is visible there.

[0044] With regard to the transport pallet 20, it should also be noted that the orientation of the rectangular profiles forming the forklift pockets 22 should be aligned perpendicular to the longitudinal axis of the tube 2 in order to reduce deflection under load.

Claims

[1] Reconstructible heavy-duty support element (10) for monopiles (2) and ship hulls, comprising at least: - a geotextile container with a cover (11), - a filling of a compacted, fine-grained bulk material placed into the interior enclosed by the shell (11); - several horizontally installed, grid-shaped reinforcement elements (13, 13.1, ...,13.6) which are placed in the installed filling in several spaced-apart intermediate layers (14.1,...14.6) and which cover at least 90% of the cross-section enclosed by the shell. [2] Heavy-duty support element (10) according to claim 1, characterized by , that the shell (11) is formed from at least one section of a fabric-reinforced geotextile membrane. [3] Heavy-duty support element (10) according to claim 1 or 2, characterized by , that the container has a bottom (12) which is connected to the shell (11). [4] Heavy-duty support element (10) according to one of claims 1 to 3, characterized by , that the reinforcement elements (13, 13.1, ...,13.6) are formed from biaxial geogrid sections. [5] Heavy-duty support element (10) according to any one of the preceding claims, characterized by that the filling consists of coal boiler ash. [6] Heavy-duty support element (10) according to any one of the preceding claims, characterized by that the filling is hydraulically installed and compacted. [7] Heavy-duty support element (10) according to claim 6, characterized by that the shell (11) and / or the base (12) are lined with an inner layer of a filter fleece. [8] Heavy-duty support element (10) according to at least one of claims 3 to 7, characterized by , that a drainage layer is installed at the bottom (12) of the container. [9] Heavy-duty support element (10) according to at least one of the preceding claims, characterized by, that the height of the intermediate layer (14.1) of the filling between the floor (12) and the adjacent reinforcement element (13.1) or between adjacent reinforcement elements (13.2,...,13.6) is between 15 cm and 40 cm. [10] Heavy-duty support element (10) according to any one of the preceding claims, characterized by , that the height of the filling as a top layer (15) in the uppermost layer is at least 15 cm. [11] Heavy-duty support element (10) according to any one of the preceding claims, characterized by , that the total height of the heavy-duty support element (10) is less than half the diameter of the shell (11). [12] Method for manufacturing a demountable heavy-duty support element (10) comprising at least the following steps: a) an empty container comprising at least one shell (11) with a round cross-section is placed on a base; b) the container is filled hydraulically or mechanically, the filling process beginning with the introduction of a first layer of soil at least 15 cm thick (14.1) and its compaction; c) A first grid-shaped reinforcement element (13.1) is placed on the floor layer (14.1); d) a further intermediate layer (14.2, ...,14.6) of the filling with a height of less than or equal to ≤30 cm is installed, on which a further grid-shaped reinforcement element (13.2, ...,13.6) is placed; e) Step d) is repeated until a target height is reached; f) as the top layer, a top layer (15) of the filling is installed with at least half the height of the intermediate layers (13.2, ... , 13.6). [13] Method according to claim 12, characterized by, that a geotextile container consisting of a shell (11) and an attached base (12) is used as the container, which is suspended and secured against being pulled down during filling. [14] Method according to claim 12 or 13, characterized by , that a geogrid is used as a reinforcement element (14, 14.1, ...,14.6). [15] Method according to at least one of claims 12 to 14, characterized by , that the fill layer is installed starting from the center of the floor (12) or the underlying reinforcement element (14) towards the outside. [16] Method according to any one of claims 12 to 15, characterized by that coal boiler ash is used as filling.

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