Connection device for offshore wind power foundation, offshore wind power foundation and recycling method thereof

Abstract

The application provides a connecting device of an offshore wind power foundation, the offshore wind power foundation and a recycling method thereof, and the recycling method comprises the following steps: removing the equipment on the original single-pile foundation, underwater cutting the original single-pile foundation at a depth of 1-2 meters below the mud surface, and recycling the old single-pile foundation buried in the soil; sequentially performing underwater sinking and soil sinking on a two-unit body formed by the connecting device and the stand column, inserting the top of the old single-pile foundation into the cavity of the inner cylinder, and performing grouting in the cavity after the two-unit body is sunk to the position, so that the grout fills the gap between the inner cylinder and the old single-pile foundation. The original single-pile foundation can be recycled, the removal of the foundation in the soil can be avoided, and the cost caused by the removal and replacement of the entire offshore wind power foundation can be reduced. Moreover, the original old single-pile foundation can increase the strength of the soil at the site, and is beneficial to improving the bearing capacity of the new offshore wind power foundation.

Description

Technical Field

[0001] This invention relates to the field of offshore wind power technology, and in particular to a connection device for offshore wind power foundations, an offshore wind power foundation and a method for its reuse. Background Technology

[0002] Compared to traditional fossil fuels, wind energy is cleaner, lower in cost, and boasts advantages such as wide development potential, safety, and inexhaustible energy resources. Compared to onshore wind power, offshore wind power offers advantages such as higher wind speeds, lower turbulence, and no need to occupy arable land. Currently, most offshore wind turbine foundations in my country use monopile foundations, which are simple in design and have mature installation technology. Offshore wind turbine foundations are typically made of steel, which corrodes due to years of seawater exposure. After a certain period of use, they will face gradual dismantling. Reinstalling new offshore wind turbine foundations inevitably requires significant investment, making cost reduction a pressing issue that needs to be addressed. Summary of the Invention

[0003] The present invention aims to at least partially solve one of the technical problems in the related art. To this end, the embodiments of the present invention provide a connection device for offshore wind power foundations, an offshore wind power foundation and a method for its reuse, so that the original wind power foundations can be reused and the costs caused by dismantling and replacing offshore wind power foundations can be reduced.

[0004] One embodiment of the present invention provides a connection device for an offshore wind power foundation, comprising: a top cover, an outer cylinder, and an inner cylinder. The upper end face of the top cover is adapted to be fixedly connected to a column, and the top cover has vertical grouting holes. The outer cylinder has an upper port and a lower port, and the upper port of the outer cylinder is fixedly connected to the edge of the lower end face of the top cover. The inner cylinder has an upper port and a lower port, and the upper port of the inner cylinder is fixedly connected to the center position of the lower end face of the top cover, forming a chamber for inserting an old monopile foundation. The grouting holes communicate with the chamber. Several partitions are fixedly connected between the outer side wall of the inner cylinder and the inner side wall of the outer cylinder, dividing the annular space enclosed between the outer cylinder and the inner cylinder into multiple compartments. Drainage holes are provided on the top cover at the top of each compartment.

[0005] This invention features an inner cylinder for connecting to existing wind turbine foundations, allowing for their reuse. Grouting holes connected to the inner cylinder in the top cover enable underwater grouting after connection, ensuring a stable connection between the support column and the existing foundation and increasing soil strength. An outer cylinder provides more stable support for the support column. Drainage holes in each compartment allow for "negative pressure" sinking during offshore wind turbine foundation placement and leveling operations. When further sinking becomes impossible, water is pumped from the corresponding chambers and / or compartments to adjust the pressure, achieving "negative pressure" sinking and ensuring the offshore wind turbine foundation is properly positioned.

[0006] In some embodiments, a ring beam is fixed to the bottom of the top cover. The ring beam is located within the chamber and the compartment, and its height is less than that of the outer cylinder. By installing the ring beam within the chamber, the gripping force between the top cover and the grout after grouting can be increased, improving connection stability. Similarly, by installing the ring beam within the compartment, the gripping force between the top cover and the underwater soil can be increased, improving the stability of the underwater support.

[0007] In some embodiments, a grouting pipe is fixedly connected to the cavity. The grouting pipe has an inlet and an outlet. The inlet of the grouting pipe is fixedly connected to and communicates with the grouting hole of the top cover. The grouting pipe is fixedly attached to the inner wall of the inner cylinder in the vertical direction. The outlet of the grouting pipe is located on the side of the grouting pipe.

[0008] In some embodiments, a reinforcing plate is fixedly connected to the grout outlet of the grouting pipe. The reinforcing plate has a transition cavity and a grout inlet and an outlet communicating with the transition cavity. The grout inlet of the reinforcing plate is connected to the grout outlet of the grouting pipe. The reinforcing plate has an inclined surface that faces the center of the cavity and slopes upwards. The grout outlet of the reinforcing plate is located on the inclined surface. By setting the reinforcing plate, on the one hand, it prevents the soil from damaging the protruding nozzle structure during subsidence, and the inclined surface of the reinforcing plate can increase the number of grout outlets. On the other hand, it can improve the gripping force between the top cover and the grout after grouting.

[0009] In some embodiments, there are multiple grouting holes, each grouting hole is connected to a grouting pipe, the multiple grouting pipes are arranged on the inner wall of the inner cylinder, and each reinforcing plate is provided with multiple grout outlets, the grout outlets of the reinforcing plate are connected to nozzles.

[0010] In some embodiments, the outer cylinder and the inner cylinder are of equal height.

[0011] Another embodiment of the present invention proposes an offshore wind power foundation, comprising: a column, an existing monopile foundation, and a connection device for the offshore wind power foundation; the lower end face of the column is fixedly connected to the center position of the upper end face of the top cover; the upper end of the existing monopile foundation is inserted into the cavity of the inner cylinder, the axis of the existing monopile foundation is collinear with the axis of the column, and the outer diameter of the existing monopile foundation is greater than or equal to the outer diameter of the column.

[0012] This invention enables the rapid replacement of offshore wind turbine foundations at their original locations by setting up a connection device for the wind turbine foundation.

[0013] In some embodiments, a plurality of diagonal braces are fixedly connected between the upper end face of the top cover and the side wall of the column. This can improve the connection strength between the column and the top cover.

[0014] In some embodiments, the diagonal bracing includes a first diagonal bracing and a second diagonal bracing, wherein the length of the first diagonal bracing is greater than the length of the second diagonal bracing, and the first and second diagonal bracings are arranged alternately around the column. The alternating arrangement of long and short diagonal bracings can further improve the connection strength between the column and the roof.

[0015] A third aspect of the present invention provides a method for reusing the above-mentioned offshore wind power foundation, comprising the following steps:

[0016] The equipment on the original monopile foundation is removed. The original monopile foundation is then cut underwater at a depth of 1-2 meters below the mud surface. The upper monopile foundation after cutting is lifted and retrieved, and the old monopile foundation buried in the soil is prepared for reuse. The two-piece structure formed by fixing the column and the connection device of the offshore wind power foundation through the hoisting device is then sequentially sunk underwater and into the soil. The top of the old monopile foundation is inserted into the cavity of the inner cylinder. When the two-piece structure cannot continue to sink during the sinking process in the soil, the drainage device above the sea surface is connected to the drainage hole and grouting hole through the pipeline. The water is drained out through the grouting hole and / or drainage hole to regulate the pressure of the cavity and each compartment. After the two-piece structure is sunk into place, the grouting device above the sea surface is connected to the grouting port through the pipeline and grout is injected into the cavity. The grout fills the gap between the inner cylinder and the old monopile foundation, fixing the old monopile foundation and the two-piece structure together to form a whole.

[0017] This invention allows for the reuse of existing monopile foundations, avoiding the demolition of in-soil foundations and reducing the costs associated with dismantling and replacing all offshore wind turbine foundations. Furthermore, the existing monopile foundations can increase the soil strength at the turbine location, which is beneficial for improving the bearing capacity of the new offshore wind turbine foundation. Attached Figure Description

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings.

[0019] in:

[0020] Figure 1 This is a schematic diagram of the connection device of the offshore wind power foundation in an embodiment of the present invention;

[0021] Figure 2 yes Figure 1 An enlarged schematic diagram of part A in the middle;

[0022] Figure 3 yes Figure 1 A bottom view of the top cover (the chamber is cylindrical);

[0023] Figure 4 yes Figure 1 A bottom view of the top cover (the chamber is hexagonal columnar);

[0024] Figure 5 This is a schematic diagram of the structure of an offshore wind power foundation in an embodiment of the present invention;

[0025] Figure 6 yes Figure 5 A top view (the chamber is cylindrical);

[0026] Figure 7 yes Figure 5 A top view (the chamber is hexagonal columnar);

[0027] Figure 8 This is a flowchart of the method for reusing offshore wind power foundations in an embodiment of the present invention;

[0028] Figure label:

[0029] 1-Column; 2-First diagonal brace; 3-Second diagonal brace; 4-Top cover; 5-Ring beam; 6-Outer cylinder; 7-Inner cylinder; 8-Old single pile foundation; 9-Grouting pipe; 10-Reinforcing plate; 11-Sprayer head; 12-Cavity; 13-Section chamber. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0031] The following description, with reference to the accompanying drawings, describes the connection device for offshore wind power foundations, the offshore wind power foundations themselves, and the method for their reuse, according to embodiments of the present invention.

[0032] like Figure 1-4 As shown, one embodiment of the present invention proposes a connection device for an offshore wind power foundation, comprising: a top cover 4, an outer cylinder 6, and an inner cylinder 7. The upper end face of the top cover 4 is adapted to be fixedly connected to a column 1, and the top cover 4 has a vertical grouting hole. The outer cylinder 6 has an upper port and a lower port, and the upper port of the outer cylinder 6 is fixedly connected to the edge of the lower end face of the top cover 4. The inner cylinder 7 has an upper port and a lower port, and the upper port of the inner cylinder 7 is fixedly connected to the center position of the lower end face of the top cover 4, forming a chamber 12 for inserting an old monopile foundation 8. The grouting hole communicates with the chamber 12. Several partitions are fixedly connected between the outer side wall of the inner cylinder 7 and the inner side wall of the outer cylinder 6, dividing the annular space between the outer cylinder 6 and the inner cylinder 7 into multiple compartments 13. A drainage hole is provided on the top cover 4 at the top of each compartment 13.

[0033] This invention features an inner cylinder 7 for connecting to existing wind turbine foundations, allowing for their reuse. A grouting hole connected to the inner cylinder 7 is provided in the top cover 4, enabling underwater grouting after connection to the existing foundation. This ensures a stable connection between the column 1 and the original foundation and increases soil strength. An outer cylinder 6 provides more stable support for the column 1. Drainage holes in each compartment 13 allow for "negative pressure" sinking during the offshore wind turbine foundation's leveling and lowering process. If further sinking is impossible, water can be pumped from the corresponding chamber 12 and / or compartment 13 to adjust the pressure within each compartment, achieving "negative pressure" sinking and ensuring the offshore wind turbine foundation is properly positioned.

[0034] Furthermore, the top cover 4 is disc-shaped, the outer cylinder 6 is fixedly connected to the lower edge of the top cover 4, and the center line of the inner cylinder 7 coincides with the center line of the outer cylinder 6.

[0035] Furthermore, the chamber 12 of the inner cylinder 7 can be cylindrical or a regular polygon, such as a regular hexagon. The distance between the inner wall of the inner cylinder 7 and the outer wall of the original wind power foundation is 0.5 to 1-2 meters.

[0036] In some embodiments, a ring beam 5 is fixed to the bottom of the top cover 4. The ring beam 5 is located within the chamber 12 and the compartment 13, and the height of the ring beam 5 is less than the height of the outer cylinder 6. By setting the ring beam 5 within the chamber 12, the gripping force between the top cover 4 and the grout after grouting can be increased, thereby improving the connection stability. By setting the ring beam 5 within the compartment 13, the gripping force between the top cover 4 and the underwater soil can be increased, thereby improving the stability of the underwater support.

[0037] Furthermore, the ring beam 5 is a steel frame arranged in a crisscross pattern.

[0038] Furthermore, the height of the ring beam 5 is 1 / 10 to 1 / 5 of the height of the outer cylinder 6. The height of the ring beam 5 should not be too high, as this will increase the resistance of the seawater to the overall device during sinking. The height of the ring beam 5 should also not be too low, as this will weaken the gripping force with the grout or soil.

[0039] In some embodiments, a grouting pipe 9 is fixedly connected inside the chamber 12. The grouting pipe 9 has a grout inlet and a grout outlet. The grout inlet of the grouting pipe 9 is fixedly connected to and communicates with the grouting hole of the top cover 4. The grouting pipe 9 is fixedly attached to the inner wall of the inner cylinder 7 in a vertical direction. The grout outlet of the grouting pipe 9 is located on the side of the grouting pipe 9.

[0040] Furthermore, the grouting pipe 9 is welded and fixed to the inner wall of the inner cylinder 7.

[0041] In some embodiments, a reinforcing plate is fixedly connected to the grout outlet of the grouting pipe 9. The reinforcing plate has a transition cavity and a grout inlet and an outlet communicating with the transition cavity. The grout inlet of the reinforcing plate is connected to the grout outlet of the grouting pipe 9. The reinforcing plate has an inclined surface that faces the center of the chamber 12 and slopes upwards. The grout outlet of the reinforcing plate is located on the inclined surface. By setting the reinforcing plate, on the one hand, it prevents the soil from damaging the structure of the protruding nozzle 11 during subsidence, and the inclined surface of the reinforcing plate can increase the number of grout outlets. On the other hand, it can improve the gripping force between the top cover 4 and the grout after grouting.

[0042] Furthermore, the longitudinal section of the reinforcing plate is a right trapezoid with its hypotenuse at the bottom. The two sides of the hypotenuse are a long side and a short side that are set vertically. The long side is fixedly connected to the side wall of the inner cylinder 7, and the top side is set horizontally.

[0043] In some embodiments, a plurality of grouting holes are provided, each grouting hole is connected to a grouting pipe 9, the plurality of grouting pipes 9 are arranged on the inner wall of the inner cylinder 7, and each reinforcing plate is provided with a plurality of grout outlets, the grout outlets of the reinforcing plate being connected to nozzles 11.

[0044] In some embodiments, the outer cylinder 6 and the inner cylinder 7 have the same height.

[0045] like Figure 5-7 As shown, another embodiment of the present invention proposes an offshore wind power foundation, including: a column 1, an old monopile foundation 8 and a connection device for the above-mentioned offshore wind power foundation; the lower end face of the column 1 is fixedly connected to the center position of the upper end face of the top cover 4; the upper end of the old monopile foundation 8 is inserted into the cavity 12 of the inner cylinder 7, the axis of the old monopile foundation 8 is collinear with the axis of the column 1, and the outer diameter of the old monopile foundation 8 is greater than or equal to the outer diameter of the column 1.

[0046] This invention enables the rapid replacement of offshore wind turbine foundations at their original locations by setting up a connection device for the wind turbine foundation.

[0047] In some embodiments, a plurality of diagonal braces are fixedly connected between the upper end face of the top cover 4 and the side wall of the column 1. This can improve the connection strength between the column 1 and the top cover 4.

[0048] In some embodiments, the diagonal bracing includes a first diagonal brace 2 and a second diagonal brace 3, wherein the length of the first diagonal brace 2 is greater than the length of the second diagonal brace 3, and the first diagonal brace 2 and the second diagonal brace 3 are arranged alternately around the column 1. The alternating arrangement of long and short diagonal braces can further improve the connection strength between the column 1 and the top cover 4.

[0049] Furthermore, the upper end of the first diagonal brace 2 is fixedly connected to the column 1, and the lower end of the first diagonal brace 2 is fixedly connected to the edge of the upper surface of the top cover 4. The upper end of the second diagonal brace 3 is fixedly connected to the column 1, and the lower end of the second diagonal brace 3 is fixedly connected to the upper surface of the top cover 4. The lower end of the second diagonal brace 3 is located between the lower end of the first diagonal brace 2 and the column 1, and the upper end of the second diagonal brace 3 is located between the upper end of the first diagonal brace 2 and the top cover 4.

[0050] Furthermore, the tilt angle of the first diagonal brace 2 is equal to the tilt angle of the second diagonal brace 3.

[0051] Furthermore, there are 6 first diagonal braces 2 and 6 second diagonal braces 3, and the spacing between adjacent first diagonal braces 2 and second diagonal braces 3 is equal.

[0052] The inventors discovered that the corrosion rate of monopile foundations buried in underwater soil is slower than that of monopile foundations directly in contact with seawater. This is because the currents in the seawater constantly erode the monopile foundation, and the salt in the seawater also continuously corrodes it. Since the monopile foundation is made of steel, although the corrosion rate of monopile foundations buried in soil is slow, for safety reasons, they can only be reused once at most.

[0053] like Figure 8 As shown, a third aspect of the present invention proposes a method for reusing the above-mentioned offshore wind power foundation, comprising the following steps:

[0054] S1, dismantle the blades, nacelle, tower and other equipment on the original monopile foundation, cut the original monopile foundation underwater in the horizontal direction at a depth of 1-2 meters below the mud surface, lift and retrieve the cut upper monopile foundation, and leave the old monopile foundation 8 buried in the soil in the original position for reuse.

[0055] S2, after the two-piece structure formed by the connection device of the column 1 and the offshore wind power foundation is transported to the location, it is successively sunk underwater and sunk in the soil by the hoisting device. The top of the old single pile foundation 8 is inserted into the cavity 12 of the inner cylinder 7. When the two-piece structure cannot continue to sink in the soil, the drainage device above the sea surface is connected to the drainage hole and the grouting hole through the pipeline. The drainage is discharged outward through the grouting hole and / or the drainage hole to adjust the pressure of the cavity 12 and each compartment 13.

[0056] S3. After the twin-unit structure is lowered into place, the grouting device located above the sea surface is connected to the grouting port through the pipeline and grouting is performed in the chamber 12. The grout fills the gap between the inner cylinder 7 and the old single pile foundation 8, so that the old single pile foundation 8 and the twin-unit structure are fixedly connected to form a whole.

[0057] This invention allows for the reuse of existing monopile foundations, avoiding the demolition of in-soil foundations and reducing the costs associated with dismantling and replacing all offshore wind turbine foundations, as well as the amount of steel used. Furthermore, the existing monopile foundations can increase the soil strength at the turbine location, which is beneficial for improving the bearing capacity of the new offshore wind turbine foundation.

[0058] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0059] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0060] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0061] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0062] In this invention, the term "some embodiments," etc., refers to specific features, structures, materials, or characteristics described in connection with that embodiment, which are included in at least one embodiment of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiments. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments. Moreover, those skilled in the art can combine and integrate the different embodiments described in this specification and the features of the different embodiments without contradiction.

[0063] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A connection device for an offshore wind power foundation, characterized in that, include: The top cover, the upper end face of which is adapted to be fixedly connected to the column, and the top cover is provided with a vertical grouting hole; The outer cylinder has an upper port and a lower port, and the upper port of the outer cylinder is fixedly connected to the edge of the lower end face of the top cover; The inner cylinder has an upper port and a lower port. The upper port of the inner cylinder is fixedly connected to the lower end face of the top cover near the center, forming a chamber for inserting an old monopile foundation. The grouting hole communicates with the chamber. Several partitions are fixedly connected between the outer side wall of the inner cylinder and the inner side wall of the outer cylinder, dividing the annular space between the outer cylinder and the inner cylinder into multiple compartments. A drainage hole is provided on the top cover at the top of each compartment. A grouting pipe is fixedly connected to the chamber, and the grouting pipe has a grout inlet and a grout outlet. The grout inlet of the grouting pipe is fixedly connected to and communicates with the grouting hole of the top cover. The grouting pipe is fixedly attached to the inner wall of the inner cylinder in a vertical direction. The grout outlet of the grouting pipe is arranged on the side of the grouting pipe. A reinforcing plate is fixedly connected to the grout outlet of the grouting pipe. The reinforcing plate has a transition cavity and a grout inlet and an grout outlet communicating with the transition cavity. The grout inlet of the reinforcing plate is connected to the grout outlet of the grouting pipe. The reinforcing plate has an inclined surface that faces the center of the cavity and is inclined upward. The grout outlet of the reinforcing plate is located on the inclined surface.

2. The connection device for offshore wind power foundations according to claim 1, characterized in that, A ring beam is fixed to the bottom of the top cover. The ring beam is located inside the cavity and the compartment. The height of the ring beam is less than the height of the outer cylinder.

3. The connection device for offshore wind power foundations according to claim 1, characterized in that, The grouting hole is provided in multiple ways, and each grouting hole is connected to a grouting pipe. The multiple grouting pipes are arranged on the inner wall of the inner cylinder. Each reinforcing plate is provided with multiple grout outlets, and the grout outlets of the reinforcing plate are connected to nozzles.

4. The connection device for offshore wind power foundations according to claim 1, characterized in that, The outer cylinder and the inner cylinder are of equal height.

5. An offshore wind power foundation, characterized in that, include: The connection device for offshore wind power foundations as described in any one of claims 1-4; A column, the lower end face of which is fixedly connected to the center position of the upper end face of the top cover; An old monopile foundation, the upper end of which is inserted into the cavity of the inner cylinder, the centerline of which is collinear with the centerline of the column, and the outer diameter of which is greater than or equal to the outer diameter of the column.

6. The offshore wind power foundation according to claim 5, characterized in that, Several diagonal braces are fixedly connected between the upper end face of the top cover and the side wall of the column.

7. The offshore wind power foundation according to claim 6, characterized in that, The diagonal bracing includes a first diagonal bracing and a second diagonal bracing. The length of the first diagonal bracing is greater than the length of the second diagonal bracing. The first diagonal bracing and the second diagonal bracing are arranged alternately around the column.

8. A method for reusing an offshore wind power foundation as described in any one of claims 5-7, characterized in that, Includes the following steps: The equipment on the original monopile foundation was removed, and the original monopile foundation was cut underwater in the horizontal direction at a depth of 1-2 meters below the mud surface. The upper monopile foundation after cutting was lifted and retrieved, and the old monopile foundation buried in the soil was prepared for reuse. The two-piece structure, formed by fixing the column and the connection device of the offshore wind power foundation through a hoisting device, is sequentially sunk underwater and sunk in the soil. The top of the old monopile foundation is inserted into the cavity of the inner cylinder. When the two-piece structure can no longer sink during the process of sunk in the soil, the drainage device located above the sea surface is connected to the drainage hole and the grouting hole through a pipeline. Water is drained outward through the grouting hole and / or the drainage hole to adjust the pressure of the cavity and each of the compartments. After the dual-unit structure is lowered into place, the grouting device located above the sea surface is connected to the grouting hole through a pipeline and grouts are injected into the cavity, so that the grout fills the gap between the inner cylinder and the old single pile foundation, and the old single pile foundation and the dual-unit structure are fixedly connected to form a whole.

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