A post-installation reinforcement device and installation method for offshore single pile foundation

Abstract

The invention discloses a post-installation reinforcement device for an offshore single pile foundation and an installation method. The device comprises an oblique brace, an upper sleeve ring, a lower sleeve ring and a lower ring plate; the lower sleeve ring and the lower ring plate are connected by a transverse brace, the upper sleeve ring and the lower ring plate are connected by an oblique brace, the diameter of the lower ring plate is larger than the diameters of the upper sleeve ring and the lower sleeve ring, the upper sleeve ring, the lower sleeve ring and the lower ring plate are split along the circumferential direction, an inserted pile and an anchor foundation are arranged below the lower ring plate, and the inserted pile is inserted into the anchor foundation; the device of the invention does not bear the vertical and lateral loads of the upper wind turbine, mainly provides additional pile-soil action, reinforces the foundation of the overall supporting structure, and improves the frequency; the upper sleeve ring, the lower sleeve ring and the lower ring plate adopt a split design scheme, which is convenient for later installation; each component is light in weight, does not require a special transportation and installation ship, reduces transportation and construction costs, and is more economical compared with commonly used anti-scouring schemes.

Description

Technical Field

[0001] The invention belongs to the field of wind turbine generator set monopile foundations, and in particular relates to an offshore monopile foundation post-installation reinforcement device and an installation method. Background Art

[0002] Offshore wind energy is abundant, and it is adjacent to the economically developed load centers in the east and south. The wind turbine foundation type is one of the biggest differences between offshore wind power generation and onshore wind power generation. Offshore wind turbine foundations include single piles, high pile caps, jackets, suction cylinders, gravity foundations, etc. Among them, single pile foundations are the most widely used foundation types.

[0003] The soil conditions of offshore wind farms are relatively weak, and most of the topsoil is clay, which is deep and thick. When constructing wind turbine foundations in shallow seas and intertidal zones with a water depth of no more than 20m, the soil around the wind turbine foundation will be washed away by tides and ocean currents, taking away the mud and sand around the piles and foundations, resulting in reduced bearing capacity of the piles, tilted foundations, and decreased frequency of the overall supporting structure. Since the frequency of a single pile foundation is sensitive to the elevation and stiffness of the mud surface, once the frequency drops, the acceleration of the head increases, resulting in shutdown, which greatly increases the owner's losses.

[0004] Commonly used reinforcement methods to improve the scouring of wind turbine foundations include sand blankets, riprap, and solidified soil. However, when the scouring range and depth are large, the cost of these commonly used methods is very huge. The landfill management cost for a single machine site exceeds 10 million yuan. In addition, since there are inevitably gaps between sand, stones, and solidified soil, the seawater carries away the sand and the stones sink. After a period of time, the stones will sink below the mud surface, and the mud surface elevation needs to be continuously maintained.

[0005] Based on the above reasons, it is necessary to find a low-cost and easy-to-maintain anti-scour treatment method for the monopile foundation of offshore wind turbines. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides an offshore monopile foundation post-installation reinforcement device and installation method, which can improve the rigidity of the monopile structure so that the wind turbine frequency meets the normal operating requirements; a detachable two-piece solution is adopted to facilitate later installation; no special transportation and installation ship is required, reducing transportation and construction costs.

[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a post-installation reinforcement device for an offshore single pile foundation, comprising a diagonal brace, an upper sleeve ring, a lower sleeve ring and a lower ring plate; the lower sleeve ring and the lower ring plate are connected by a transverse brace, the upper sleeve ring and the lower ring plate are connected by a diagonal brace, the diameter of the lower ring plate is larger than the diameter of the upper sleeve ring and the lower sleeve ring, the upper sleeve ring, the lower sleeve ring and the lower ring plate are split along the circumferential direction, an inserted pile and an anchor foundation are arranged below the lower ring plate, and the inserted pile is inserted into the anchor foundation.

[0008] It also includes a convex ring, a plurality of which are arranged on the outer side of the single pile, an upper sleeve ring and a lower sleeve ring are sleeved on the outer side of the convex ring, and a rubber pad is arranged on the inner side of the upper sleeve ring and the lower sleeve ring.

[0009] The surfaces of the convex ring, the diagonal brace, the upper sleeve ring, the lower sleeve ring, the lower ring plate and the inserted pile are all provided with an anti-corrosion layer.

[0010] The anchor foundation is a driven pile foundation or a suction tube pile foundation.

[0011] The upper sleeve ring, the lower sleeve ring and the lower ring plate are all divided into two half rings along the circumferential direction. The upper sleeve ring and the lower ring plate are connected to the diagonal brace by welding, the lower sleeve ring and the lower ring plate are connected by welding, and the bottom inserted pile is connected to the lower ring plate by welding.

[0012] The number and positions of the bottom inserted piles are arranged in one-to-one correspondence with the diagonal braces.

[0013] The upper sleeve ring, the lower sleeve ring and the outer side of the single pile are provided with a locking mechanism.

[0014] The lower collar and the lower ring plate are connected by hinges or rivets.

[0015] The installation method of the post-installation reinforcement device of the offshore monopile foundation of the present invention comprises the following steps:

[0016] Prefabricate the reinforcement tooling in the factory, and manufacture and connect the diagonal brace, upper collar, lower collar, lower ring plate, and inserted pile as a whole;

[0017] Driving the anchor foundation, inserting the insert pile into the anchor foundation;

[0018] The split parts of the upper collar are connected to each other, the split parts of the lower collar are connected to each other, and the split parts of the lower ring plate are connected to each other.

[0019] According to the design, multiple convex rings are welded on the surface of the single pile.

[0020] During prefabrication, hinges are installed in advance at the split ends of the lower sleeve ring and the lower ring plate, and the hinges are locked after being connected at the installation position.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects: the device described in the present invention does not bear the vertical and lateral loads of the upper fan, and mainly provides additional pile-soil function to reinforce the foundation of the overall supporting structure and increase the frequency. The present invention can increase the rigidity of the single pile structure so that the fan frequency meets the normal operating requirements; the upper collar, lower collar and lower ring plate adopt a split design scheme, which is convenient for later installation; each component is light in weight and does not require a special transportation and installation ship, reducing transportation and construction costs, which is more economical than the commonly used anti-scour solutions.

[0022] Furthermore, multiple convex rings are arranged on the outside of the single pile, and the upper ring and the lower ring are sleeved on the outside of the convex ring, which can be installed at different heights according to actual needs. Rubber pads are arranged on the inside of the upper ring and the lower ring to improve the integrity of the upper ring and the lower ring with the single pile.

[0023] Furthermore, the connection between the lower collar and the lower ring plate by hinges or rivets is more rapid and easy to implement on site.

[0024] The installation method of the offshore single pile foundation post-installation reinforcement device of the present invention is more economical than the commonly used anti-scour solution of riprap, and the expected effect of implementation is more accurate. The components of the device are all prefabricated in the factory, which greatly reduces the amount of offshore on-site operations, shortens the implementation period, and greatly saves costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of an implementable offshore single pile foundation reinforcement tooling of the present invention.

[0026] Figure 2 It is a schematic diagram of the structure of a reinforcement tooling that can be implemented in the present invention.

[0027] Figure 3 It is a schematic diagram of an implementable single pile foundation and convex ring structure of the present invention.

[0028] 1-tower, 2-single pile, 3-reinforcement tooling, 4-convex ring, 31-diagonal brace, 33-lower sleeve ring, 34-lower ring plate, 35-hinge, 4-convex ring DETAILED DESCRIPTION

[0029] The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments of the present invention in conjunction with the accompanying drawings.

[0030] Example

[0031] refer to Figure 1 and Figure 2 The tower 1 is arranged on the top of the single pile 2, and the reinforcement tooling 3 is installed above the mud surface of the single pile 2. The reinforcement tooling 3 includes a diagonal brace 31, an upper ring 32, a lower ring 33 and a lower ring plate 34. The bottom inserted pile 36 is connected to the anchor foundation 37 by grouting. It adopts a detachable two-piece split type. The upper ring 32 and the lower ring 33 are connected into a whole by a hinge 35. The hinge 35 and one end of the upper ring 32 and the lower ring 33 are pre-installed during manufacturing, which is convenient for later installation. The weight of each component is small, and no special transportation and installation ship is required, which reduces transportation and construction costs.

[0032] The upper and lower collars 32 and 33 are provided with locking mechanisms on the outer sides of the single pile 2. Specifically, a plurality of threaded holes can be provided on the upper and lower collars 32 and 33 along the circumferential direction, and reinforcement design is performed at the threaded holes. Locking bolts are installed to lock the collars 32 and the lower collars 33 with the single pile 2 respectively.

[0033] As an optional embodiment, according to the actual geological conditions of the project, the anchor foundation 37 can be a driven pile foundation or a suction tube pile foundation.

[0034] In the operation of an actual offshore wind farm, when the scouring exceeds the design value and causes the frequency to drop, resulting in the unit acceleration exceeding the limit value and shutting down, the reinforcement tooling of the present invention can be used. In addition, the tooling scheme proposed by the present invention is more economical than the commonly used anti-scouring scheme such as riprap.

[0035] refer to Figure 1 and Figure 3 In the early stage of manufacturing the single pile, multiple convex rings 4 need to be set, the convex rings are welded on the main structure of the single pile, and the upper ring 32 and the lower ring 33 are sleeved on the outside of the convex ring 4. In the later stage, the reinforcement tooling can be installed according to different scouring depths, and the height is adjusted and fixed through the convex ring 4 of the single pile foundation.

[0036] Rubber pads are provided inside the upper collar 32 and the lower collar 33 for tight connection with the main body of the single pile foundation.

[0037] Based on the solution of the present invention, it is implemented in a certain offshore wind turbine, and the height, diameter, diagonal brace and other component dimensions of the reinforcement tooling 3 can be optimized according to the actual project. Specifically, in this embodiment:

[0038] The outer diameter of the single pile 2 is D1 = 7m, the raised ring 4 on the single pile is welded with steel bars with a diameter of 15mm, and the raised ring spacing h1 = 2.8m.

[0039] The height H of the diagonal brace 31 is 10m, and the thickness is 20mm; the height h2 of the upper ring 32 is 2.8m, and the thickness is 15mm; the height h3 of the lower ring 33 is 15mm, and the thickness is 15mm; the diameter D4 of the lower ring plate 34 is 14m, and the thickness is 20mm.

[0040] The diameter D3 of the anchor foundation 37 is 2 m, and the wall thickness is 35 mm; the diameter of the bottom inserted pile 36 is 1.55 m, and it is connected to the anchor foundation 37 by grouting material.

[0041] The main structure of the monopile 2 is manufactured in the factory, and multiple convex rings 4 are welded on the surface according to design requirements.

[0042] The specific construction steps are as follows:

[0043] After the scour depth exceeded the design value and caused the wind turbine to shut down, the feasibility of using reinforcement tool 3 was evaluated

[0044] All parts of the reinforcement tooling 3 are prefabricated and connected in the factory. The diagonal brace 31, the upper collar 32, the lower collar 33, the lower ring plate 34, and the inserted pile 36 are integrally manufactured and welded. The upper collar 32, the lower collar 33, and the lower ring plate 34 are prefabricated into two pieces respectively, and hinges 35 are installed at the ends of the split parts in advance. All parts of the reinforcement tooling 3 are treated with anti-corrosion.

[0045] Drive an inserted anchor foundation 37 or install a suction tube anchor foundation near the machine site;

[0046] Transport the reinforcement tool 3 to the on-site machine location;

[0047] Install two pieces of integral reinforcement tooling and lock the hinge 35;

[0048] Complete the installation.

Claims

1. A post-installation reinforcement device for an offshore monopile foundation, characterized in that: The invention comprises an inclined brace (31), an upper sleeve ring (32), a lower sleeve ring (33) and a lower ring plate (34); the lower sleeve ring (33) and the lower ring plate (34) are connected by a transverse brace, the upper sleeve ring (32) and the lower ring plate (34) are connected by an inclined brace (31), the diameter of the lower ring plate (34) is larger than the diameters of the upper sleeve ring and the lower sleeve ring, the upper sleeve ring (32), the lower sleeve ring (33) and the lower ring plate (34) are split along the circumferential direction, an inserted pile (36) and an anchor foundation (37) are arranged below the lower ring plate (34), and the inserted pile (36) is inserted into the anchor foundation (37); and the invention also comprises a convex ring (4), a plurality of convex rings (4) are arranged on the outer side of the single pile (2), and the upper sleeve ring (32) and the lower sleeve ring (33) are arranged on the outer side of the single pile (2). The ring (32) and the lower ring (33) are sleeved on the outer side of the convex ring (4), and rubber pads are arranged on the inner sides of the upper ring (32) and the lower ring (33); the upper ring (32), the lower ring (33) and the lower ring plate (34) are divided into two half rings along the circumferential direction, the upper ring (32) and the lower ring plate (34) are welded to the diagonal support (31), the lower ring (33) and the lower ring plate (34) are welded to each other, and the bottom inserted pile (36) is welded to the lower ring plate (34); the upper ring (32) and the lower ring (33) are provided with locking mechanisms on the outer sides of the single pile (2); the split parts of the lower ring (33) and the lower ring plate (34) are connected by hinges (35) or rivets.

2. The post-installation reinforcement device for offshore monopile foundation according to claim 1, characterized in that: The surfaces of the convex ring (4), the diagonal brace (31), the upper sleeve ring (32), the lower sleeve ring (33), the lower ring plate (34) and the inserted pile (36) are all provided with an anti-corrosion layer.

3. The post-installation reinforcement device for offshore monopile foundation according to claim 1, characterized in that: The anchor foundation (37) is a driven pile foundation or a suction tube pile foundation.

4. The post-installation reinforcement device for offshore monopile foundation according to claim 1, characterized in that: The number and positions of the bottom inserted piles (36) are arranged in one-to-one correspondence with the diagonal braces (31).

5. The installation method of the offshore monopile foundation post-installation reinforcement device according to any one of claims 1 to 4, characterized in that: The following steps are involved: Prefabricate the reinforcement tooling in the factory, and manufacture and connect the diagonal brace (31), the upper collar (32), the lower collar (33), the lower ring plate (34), and the inserted pile (36) as a whole; Driving the anchor foundation (37), inserting the inserted pile (36) into the anchor foundation (37); The split parts of the upper collar (32) are connected to each other, the split parts of the lower collar (33) are connected to each other, and the split parts of the lower ring plate (34) are connected to each other.

6. The installation method according to claim 5, characterized in that: According to the design, multiple convex rings (4) are welded on the surface of the single pile (2). During prefabrication, hinges (35) are installed in advance at the split ends of the lower collar (33) and the lower ring plate (34), and the hinges (35) are locked after being connected at the installation position.

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