Anti-scouring structure suitable for offshore wind power foundation in operation period and construction method thereof

Abstract

The application discloses a scouring prevention structure suitable for a wind power foundation in an operation and maintenance period, which comprises a foundation protection structure, a supporting structure and a limiting structure; the foundation protection structure is backfilled in a scouring pit of the wind power foundation, the top elevation of the foundation protection structure is lower than the original mud surface of the wind power foundation by 1m or less, and the foundation protection structure is formed by filling base sand bags; the supporting structure is formed by filling middle-layer sand bags, arranged on the foundation protection structure, extended along the cable routing direction of the foundation periphery, and used for supporting the submarine cable; and the limiting structure is arranged on both sides of the submarine cable, formed by filling top-layer sand bags, and arranged on the supporting structure. The application further discloses a construction method of the scouring prevention structure. The application can effectively reduce the suspension height and length of the submarine cable, inhibit the scouring trend of the wind power foundation, is convenient to construct, can prolong the service life of the wind power foundation, and can avoid damaging the submarine cable.

Description

Technical Field

[0001] This invention relates to the field of offshore wind power engineering, and in particular to an anti-scour structure for offshore wind power foundations during the operation and maintenance period and its construction method. Background Technology

[0002] In recent years, more and more offshore wind farms have entered the operation and maintenance period, and the harsh marine environment has brought huge challenges to the safe operation and maintenance of offshore wind power.

[0003] Generally, the electricity generated by wind turbines in offshore wind farms is boosted by a 220kV offshore substation and then transmitted via a 220kV submarine cable to a landing point near the onshore control center for grid connection. Offshore substation foundations typically employ a multi-pile jacket structure, and due to the relatively small pile diameter, scour protection measures are generally not considered during the design phase. However, during the operation and maintenance of offshore wind farms, it has been found that scour can occur around the substation foundation. As the scour process progresses, the suspended height and length of the submarine cable gradually increase, leading to increased static tension on the cable. Under the long-term influence of ocean waves and currents, the cable itself is highly susceptible to failure. Cable failure and power outages undoubtedly result in substantial economic losses for offshore wind farms. To improve the service life of submarine cables, scour protection measures should be added to the foundations of offshore substations.

[0004] For offshore substations or wind turbine foundations in the operation and maintenance phase, the dense network of submarine cables presents a significant challenge to the installation of traditional protective measures. Both rock-laying and sand-laying methods involve lowering the cables from top to bottom, which carries a high risk of accidentally touching and damaging them.

[0005] Therefore, it is necessary to invent an anti-scour structure suitable for offshore wind power foundations during the operation and maintenance period. This structure needs to meet the following requirements: 1) easy to construct, 2) able to effectively reduce the suspension height and length of submarine cables, and able to suppress the scour trend around the offshore wind power foundation. Summary of the Invention

[0006] This invention provides an anti-scour structure and its construction method suitable for offshore wind power foundations during operation and maintenance, in order to solve the technical problems existing in the prior art. The structure and its construction method can effectively reduce the suspension height and length of submarine cables, suppress the scour tendency of offshore wind power foundations, and are easy to construct. It can also extend the service life of wind power foundations and avoid damage to submarine cables.

[0007] The present invention provides a technical solution to address the technical problems existing in the prior art: an anti-scour structure suitable for offshore wind power foundations during operation and maintenance, comprising a foundation protection structure, a support structure, and a limiting structure; the foundation protection structure is backfilled in the scour pit of the wind power foundation, with its top elevation within 1m below the original mud surface around the wind power foundation, and is formed by filling the base layer with sandbags; the support structure is formed by filling the middle layer with sandbags, is installed on the foundation protection structure, extends along the direction of the submarine cable route around the foundation, and supports the submarine cable; the limiting structure is installed on both sides of the submarine cable, is formed by filling the top layer with sandbags, and is installed on the support structure.

[0008] The planar dimensions of the basic protective structure, the supporting structure, and the limiting structure are arranged from largest to smallest.

[0009] The height of the base layer sandbag, the middle layer sandbag, and the top layer sandbag is 0.2m-0.6m.

[0010] The base layer sandbags, the middle layer sandbags, and the top layer sandbags all use a material with a strength of not less than 380g / m³. 2 It is made of polyester filament woven geotextile bags.

[0011] The seams of the base layer sandbag, the middle layer sandbag, and the top layer sandbag are sewn together using an overlock or twill stitch, with two layers of nylon thread, a stitch spacing of ≤7mm, and the strength after sewing is not less than 70% of the original fabric design strength.

[0012] The base sandbags, the middle sandbags, and the top sandbags are filled with sand having a permeability coefficient of not less than 10. - 3 Fine or medium-coarse sand with a flow rate of cm / s.

[0013] Another technical solution adopted by the present invention to solve the technical problems existing in the prior art is: a construction method for an anti-scour structure of offshore wind power foundations during the operation and maintenance period, as described above. The base sandbags, the middle sandbags, and the top sandbags are sewn on land, transported to the site by ship, and placed by divers setting towing ropes underwater and towing with winches. Sand is blown into the base sandbags, the middle sandbags, and the top sandbags by sand dredging vessels. Two sand dredging vessels are set up and respectively set on both sides of the wind power foundation to form an anchor cable tension state. The winches are set on the sand dredging vessels.

[0014] The advantages and positive effects of this invention are as follows: By arranging sandbags below and on both sides of the submarine cable and filling the sandbags with sand using an on-water dredging method, accidental contact with the submarine cable can be effectively avoided, improving operational safety. Furthermore, on-site dredging is convenient, efficient, and reduces operating costs. By setting up a basic protective structure with sandbags in the scour pit, the scour tendency of the wind turbine foundation can be effectively suppressed, protecting the surrounding soil and extending the service life of the wind turbine foundation. By setting up a submarine cable support structure with sandbags on the basic protective structure, the suspension height and length of the submarine cable can be effectively reduced. In summary, this invention can effectively reduce the suspension height and length of the submarine cable, suppress the scour tendency of offshore wind turbine foundations, and is convenient and inexpensive to construct; it can extend the service life of the wind turbine foundation and avoid damage to the submarine cable. Attached Figure Description

[0015] Figure 1 This is a side view of the present invention;

[0016] Figure 2 This is a schematic diagram of the limiting structure of the present invention.

[0017] In the diagram: 1. Submarine cable duct, 2. Submarine cable, 3. Middle layer sandbag, 4. Top layer sandbag, 5. Base layer sandbag. Detailed Implementation

[0018] To further understand the invention's content, features, and effects, the following embodiments are provided, and detailed descriptions are given below in conjunction with the accompanying drawings:

[0019] Please see Figure 1 and Figure 2 A scour protection structure suitable for offshore wind power foundations during operation and maintenance includes a foundation protection structure, a support structure, and a limiting structure.

[0020] The basic protective structure is backfilled in the scour pit of the wind power foundation, with its top elevation within 1m lower than the original mud surface around the wind power foundation. It is made of base sandbags 5.

[0021] The support structure is made of middle-layer sandbags 3, which are set on the basic protection structure and extend along the direction of the submarine cable route around the foundation to support the submarine cable 2.

[0022] The limiting structure is installed on both sides of the submarine cable 2, and is made of top-layer sandbags 4, and is installed on the supporting structure.

[0023] Submarine cable 2, emerging from cable conduit 1, is lowered along a J-shaped tube to the supporting structure. This support structure effectively reduces the cable's suspension height and length, extending its service life. A limiting structure restricts cable sway, further extending its lifespan. Backfilling the foundation protection structure within the scour pit effectively suppresses scour of the wind turbine foundation, extending its service life. Using sandbags effectively prevents accidental contact with the cable, improving operational safety.

[0024] The following improvements have also been made to this embodiment:

[0025] The basic protective structure, the supporting structure, and the limiting structure are arranged in descending order of their planar dimensions, resulting in good structural stability.

[0026] The recommended height for the base sandbag 5, the middle sandbag 3, and the top sandbag 4 is 0.2m-0.6m. In this embodiment, the length and width of the base sandbag 5 are set to 30m and 8m, respectively; the length and width of the middle sandbag 3 are set to 6m and 5m, respectively; the length and width of the top sandbag 4 are set to 4m and 2m, respectively; and the total height of all sandbags after filling is 0.5m.

[0027] The base sandbags 5, the middle sandbags 3, and the top sandbags 4 should have good strength and toughness to avoid bursting failure during dredging. In this embodiment, they all use a strength of not less than 380g / m³. 2 The geotextile bags are made of woven polyester filament and sewn together. The seams of the base layer sandbags 5, the middle layer sandbags 3, and the top layer sandbags 4 are joined using either overlock or T-stitch methods, with two layers of nylon thread and a stitch spacing ≤7mm. The post-sewing strength is not less than 70% of the original fabric's design strength to ensure construction safety. The base layer sandbags 5, the middle layer sandbags 3, and the top layer sandbags 4 are filled with fine or medium-coarse sand with a permeability coefficient of not less than 10⁻³ cm / s, which is relatively dense and helps improve the stability of the structure. In this embodiment, the content of particles larger than 0.075mm in the filling sand is greater than 85%, and the content of clay particles (d < 0.005mm) is less than 3%.

[0028] Construction method of the above-mentioned erosion protection structure:

[0029] The base sandbags 5, the middle sandbags 3, and the top sandbags 4 are sewn on land and transported to the site by ship. They are then placed using a method where divers set up tow ropes underwater and tow them with winches. Sand is blown into the base sandbags 5, the middle sandbags 3, and the top sandbags 4 using two sand-blowing vessels, one on each side of the wind turbine foundation, forming an anchor cable tension state to maintain the overall stability of the sand-blowing vessels and stabilize the position of the sandbags. The winches are mounted on the sand-blowing vessels.

[0030] During construction, the work proceeds from bottom to top, employing an on-site water reclamation method. This effectively avoids accidental contact with submarine cables, improves operational safety, facilitates construction, increases efficiency, and reduces construction costs.

[0031] Although preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other modifications under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these modifications are within the scope of protection of the present invention.

Claims

1. A construction method for scour protection structures of offshore wind turbine foundations during the operation and maintenance phase, characterized in that, The erosion protection structure includes a basic protective structure, a supporting structure, and a limiting structure; The basic protective structure is backfilled in the scour pit of the wind power foundation, with its top elevation within 1m lower than the original mud surface around the wind power foundation. It is made of base sandbags. The support structure is made of a middle layer of sandbags and is set on the basic protective structure, extending along the direction of the submarine cable route around the foundation to support the submarine cable. The limiting structure is installed on both sides of the submarine cable and is made of top-layer sandbags. It is installed on the support structure to limit the swaying of the submarine cable. The height of the base layer sandbags, the middle layer sandbags, and the top layer sandbags is 0.2m. 0.6m; The length and width of the base layer sandbags are set to 30m and 8m respectively; the length and width of the middle layer sandbags are set to 6m and 5m respectively; and the length and width of the top layer sandbags are set to 4m and 2m respectively. The construction method of the erosion protection structure is as follows: The base layer sandbags, the middle layer sandbags, and the top layer sandbags are sewn on land and transported to the site by ship. They are then placed by divers setting up tow ropes underwater and using winches to tow them. Sand is blown into the base layer sandbags, the middle layer sandbags, and the top layer sandbags using two sand-blowing vessels, which are respectively set up on both sides of the wind turbine foundation to form an anchor cable tension state. The winches are set up on the sand-blowing vessels.

2. The construction method for scour protection structures of offshore wind turbine foundations during the operation and maintenance period, as described in claim 1, is characterized in that... The base layer sandbags, the middle layer sandbags, and the top layer sandbags all use a material with a strength of not less than 380g / m³. 2 It is made of polyester filament woven geotextile bags.

3. The construction method for scour protection structures of offshore wind turbine foundations during the operation and maintenance period, as described in claim 1, is characterized in that... The seams of the base layer sandbag, the middle layer sandbag, and the top layer sandbag are sewn together using an overlock or twill stitch, with two layers of nylon thread, a stitch spacing of ≤7mm, and the strength after sewing is not less than 70% of the original fabric design strength.

4. The construction method for scour protection structures of offshore wind turbine foundations during the operation and maintenance period, as described in claim 1, is characterized in that... The base sandbags, the middle sandbags, and the top sandbags are filled with sand having a permeability coefficient of not less than 10. -3 Fine or medium-coarse sand with a flow rate of cm / s.

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