Scouring protection device for delivery submarine cable of offshore wind turbine

Abstract

The invention relates to the technical field of offshore wind power equipment, in particular to a scouring protection device for an offshore wind turbine delivery submarine cable, which comprises a submarine cable protection stone bag group, and the submarine cable protection stone bag group comprises a supporting stone bag group, a limiting stone bag group and a fixed stone bag group which are formed by arranging a plurality of stone bags. The supporting stone bag group is arranged in a suspended area of the submarine cable and located below the submarine cable to support the submarine cable, the limiting stone bag groups are located in the suspended area and located on the two sides of the submarine cable to clamp the submarine cable, the fixed stone bag group comprises a suspended covering stone bag group and a ground contact reinforcing stone bag group, and the suspended covering stone bag group is located in the suspended area and located above the submarine cable to press the submarine cable. The ground contact reinforcing stone bag group is located in a ground contact area of the submarine cable and comprises a T-shaped end stone bag group, the T-shaped end stone bag group comprises a circumferentially-arranged stone bag group and a pressing stone bag group which are arranged in a T shape, the circumferentially-arranged stone bag group extends in the circumferential direction of the concentric circle of the pile foundation, and the pressing stone bag group is arranged above the submarine cable in the extending direction of the submarine cable. And the circumferentially arranged stone bag groups are farther from the pile foundation than the compressed stone bag groups.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore wind power equipment, and in particular to a scour protection device for an offshore wind turbine transmission submarine cable. Background Art

[0002] With the continuous development of offshore wind power generation technology, the installed capacity of offshore wind turbines has increased year by year. The natural environment in which offshore wind turbines are located is relatively harsh. The area around the installation foundation of the underwater pile foundation has been eroded by water for a long time, and the loss of sand and soil has formed pits, resulting in a reduction in the burial depth of the installation foundation of the underwater pile foundation. The submarine cables laid under the seabed are exposed or even partially suspended, which is detrimental to the structural safety of the wind turbines and the operation and maintenance of the wind farm. In order to avoid the harm caused by local scouring of the underwater pile foundation, the existing treatment method is mainly to arrange riprap, sandbags, etc. to suppress the development of local pits. However, the existing technology has the following shortcomings: the stability of protective measures such as riprap and sandbags is poor, and they will move under the action of water, causing secondary scouring and increasing the risk of large-scale exposure of submarine cables. Summary of the invention

[0003] The object of the present invention is to provide a scour protection device for an offshore wind turbine transmission submarine cable, which can improve stability, help suppress secondary scours, and protect the submarine cable.

[0004] To achieve this object, the present invention adopts the following technical solutions:

[0005] Provided is a scour protection device for an offshore wind turbine transmission cable, comprising:

[0006] A group of stone bags for protecting submarine cables comprises a supporting stone bag group, a limiting stone bag group and a fixed stone bag group formed by a plurality of stone bags arranged in an arrangement. The supporting stone bag group is arranged in a suspended area of ​​the submarine cable, the supporting stone bag group is located below the submarine cable to support the submarine cable, the limiting stone bag group is located in the suspended area, the stone bags of the limiting stone bag group are located on both sides of the submarine cable to clamp the submarine cable, the fixed stone bag group comprises a suspended covering stone bag group and a ground-contacting reinforcement stone bag group, the suspended covering stone bag group is located in the suspended area and above the submarine cable to compact the submarine cable, The ground-contacting reinforcement stone bag group is located in the ground-contacting area of ​​the submarine cable, and the ground-contacting reinforcement stone bag group includes a T-shaped end stone bag group, and the T-shaped end stone bag group includes a circumferentially arranged stone bag group and a compacted stone bag group. The circumferentially arranged stone bag group extends circumferentially along the concentric circles of the pile foundation, and the compacted stone bag group is arranged above the submarine cable along the extension direction of the submarine cable. The compacted stone bag group is vertically connected to the midpoint of the circumferentially arranged stone bag group, so that the circumferentially arranged stone bag group and the compacted stone bag group are arranged in a T-shape, and the circumferentially arranged stone bag group is farther away from the pile foundation than the compacted stone bag group.

[0007] Optionally, the center of the stone bag of the fixed stone bag group is located vertically above the submarine cable.

[0008] Optionally, it also includes a pile-surrounding spoiler stone bag group formed by arranging multiple stone bags, the pile-surrounding spoiler stone bag group includes a first stone bag group arranged along the outer wall curved surface of the pile foundation, and also includes a second stone bag group arranged circumferentially along the concentric circles of the pile foundation, the second stone bag group is close to the first stone bag group.

[0009] Optionally, the area where the spoiler stone bag group around the pile is located includes a horseshoe vortex generating area in front of the pile foundation;

[0010] And / or, the area where the spoiler stone bag group around the pile is located includes the lateral streamline contraction area of ​​the pile foundation;

[0011] And / or, the area where the spoiler stone bag group around the pile is located includes the rear vortex shedding area of ​​the pile foundation;

[0012] And / or, the vertical projection of the spoiler stone bag group around the pile covers part of the vertical projection of the area where the submarine cable is located.

[0013] Optionally, it also includes a backfill pit stone bag group formed by arranging a plurality of the stone bags, and the backfill pit stone bag group is used to fill the pit so that the depth of the filled pit is less than a maximum preset scouring depth.

[0014] Optionally, the backfill pit stone bag group covers the edge area of ​​the protective sea cable stone bag group.

[0015] Optionally, the top elevation of the backfill scouring pit stone bag group is at most flush with the surrounding seabed;

[0016] And / or, the top elevation of the backfill pit stone bag group is at most flush with the top elevation of the protective submarine cable stone bag group.

[0017] Optionally, the elevations of the stone bags adjacent to each other in the protective cable stone bag group, the pile surrounding spoiler stone bag group and the backfill pit stone bag group are smoothly transitioned;

[0018] And / or, the stone bags at the edge of the protection area where the protective sea cable stone bag group, the pile spoiler stone bag group and the backfill pit stone bag group are located as a whole are one layer, and the stone bags inside the protection area are more than one layer.

[0019] Optionally, the vertical projection of the protection area where the protective sea cable stone bag group, the pile peri-spoiler stone bag group and the backfill pit stone bag group are located as a whole is fan-shaped.

[0020] Optionally, the stone bags at the bottom layer of the protective cable stone bag group, the pile surrounding spoiler stone bag group and the backfill pit stone bag group are closely arranged;

[0021] And / or, all the stone bags of the backfill pit stone bag group are tightly arranged;

[0022] And / or, all the stone bags of the spoiler stone bag group around the pile are tightly arranged.

[0023] Beneficial effects of the present invention:

[0024] The present invention provides a scour protection device for an offshore wind turbine transmission submarine cable, comprising a group of stone bags for protecting the submarine cable, wherein the group of stone bags for protecting the submarine cable comprises a supporting stone bag group, a limiting stone bag group and a fixed stone bag group formed by a plurality of stone bags arranged. The supporting stone bag group is arranged in a suspended area of ​​the submarine cable, and the supporting stone bag group is located below the submarine cable to support the submarine cable. The limiting stone bag group is located in the suspended area, and the stone bags of the limiting stone bag group are located on both sides of the submarine cable to clamp the submarine cable to prevent the submarine cable from moving laterally. The fixed stone bag group comprises a suspended covering stone bag group and a ground-touching reinforcement stone bag group, and the suspended covering stone bag group is located in the suspended area and above the submarine cable to compress the submarine cable, reduce the hydrodynamic amplitude of the submarine cable, and increase the stability of the stone bag below. The ground-contact reinforcement stone bag group is located in the ground-contact area of ​​the submarine cable. The ground-contact reinforcement stone bag group includes a T-shaped end stone bag group. The T-shaped end stone bag group includes a circumferentially arranged stone bag group and a compacted stone bag group. The circumferentially arranged stone bag group extends along the circumference of the concentric circles of the pile foundation. The compacted stone bag group is arranged above the submarine cable along the extension direction of the cable. The compacted stone bag group is vertically connected to the midpoint of the circumferentially arranged stone bag group, so that the circumferentially arranged stone bag group and the compacted stone bag group are arranged in a T-shape, and the circumferentially arranged stone bag group is farther away from the pile foundation than the compacted stone bag group. The T-shaped end stone bag group can avoid end scouring and sinking instability. First of all, compared with sandbags and riprap, stone bags have better stability, and through the reasonable planning and design of the above-mentioned stone bag group, secondary scouring can be suppressed to the greatest extent, preventing large-scale exposure of the submarine cable and protecting the submarine cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of a layer of stone bag groups for flow disturbance around piles provided by an embodiment of the present invention;

[0026] Figure 2 It is a schematic diagram of the structure of a two-layer stone bag group for flow disturbance around piles provided by an embodiment of the present invention;

[0027] Figure 3 It is a schematic diagram of the structure of a layer of stone bag group for protecting a No. 1 submarine cable and a layer of stone bag group for protecting a No. 2 submarine cable provided in an embodiment of the present invention;

[0028] Figure 4 It is a schematic diagram of the structure of a second-layer stone bag group for protecting a No. 1 submarine cable and a second-layer stone bag group for protecting a No. 2 submarine cable provided by an embodiment of the present invention;

[0029] Figure 5It is a schematic diagram of the structure of a three-layer stone bag group for protecting a No. 1 submarine cable and a four-layer stone bag group for protecting a No. 1 submarine cable provided in an embodiment of the present invention;

[0030] Figure 6 It is a structural schematic diagram of a layer of stone bag groups for backfilling a scouring pit provided by an embodiment of the present invention;

[0031] Figure 7 is a schematic diagram of an experimental water tank provided in an embodiment of the present invention;

[0032] Figure 8 is a topographic map scanned at the beginning of an experiment provided by an embodiment of the present invention;

[0033] Fig. 9 It is a topographic map scanned after 2 hours of experiment provided by an embodiment of the present invention;

[0034] Fig.10 This is a topographic map scanned after 8 hours of experiment provided by an embodiment of the present invention.

[0035] In the figure:

[0036] 1. Pile foundation; 2. No. 1 submarine cable; 3. No. 2 submarine cable;

[0037] 4. One layer of stone bags for disturbance flow around piles; 5. Two layers of stone bags for disturbance flow around piles; 6. One layer of stone bags for protecting No. 1 submarine cable; 7. One layer of stone bags for protecting No. 2 submarine cable; 8. Two layers of stone bags for protecting No. 1 submarine cable; 9. Two layers of stone bags for protecting No. 2 submarine cable; 10. Three layers of stone bags for protecting No. 1 submarine cable; 11. Four layers of stone bags for protecting No. 1 submarine cable; 12. One layer of stone bags for backfilling the scouring pit;

[0038] 13. Sand bed; 14. Gentle slope; 15. Experimental fan foundation; 16. Flow meter; 17. Laser terrain scanner. DETAILED DESCRIPTION

[0039] Before any embodiments of the application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the above drawings.

[0040] In this application, the terms "comprises", "includes", "has" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0041] In this application, the term "and / or" is a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects before and after are in an "and / or" relationship.

[0042] In the present application, the terms "connect", "combine", "couple", and "install" may refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, direct connection refers to two parts or components being connected together without the need for an intermediate piece, and indirect connection refers to two parts or components being connected to at least one intermediate piece respectively, and the two parts or components being connected via the intermediate piece. In addition, "connect" and "couple" are not limited to physical or mechanical connections or couplings, and may include electrical connections or couplings.

[0043] In the present application, it will be understood by those of ordinary skill in the art that relative terms (e.g., "about," "approximately," "substantially," etc.) used in conjunction with quantities or conditions include the values ​​and have the meaning indicated by the context. For example, the relative terms include at least the degree of error associated with the measurement of a specific value, the tolerances caused by manufacturing, assembly, and use associated with a specific value, and the like. Such terms should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to plus or minus a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​that do not use relative terms should also be disclosed as specific values ​​with tolerances. In addition, "substantially" may refer to plus or minus a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) on the basis of the indicated angle when expressing a relative angular position relationship (e.g., substantially parallel, substantially perpendicular).

[0044] In this application, it will be understood by those skilled in the art that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0045] In the present application, the terms "upper", "lower", "left", "right", "front", "back" and other directional words are described based on the orientation and positional relationship shown in the accompanying drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element. It should also be understood that directional words such as upper side, lower side, left side, right side, front side, back side, etc. not only represent the positive orientation, but can also be understood as the lateral orientation. For example, the bottom can include directly below, lower left, lower right, lower front, and lower back, etc.

[0046] The natural environment of offshore wind turbines is relatively harsh. The area around the installation foundation of the wind turbine pile is easily eroded by water flow for a long time, and the sand in the area around the installation base of the wind turbine pile is eroded and lost, resulting in a reduction in the burial depth of the installation foundation of the wind turbine pile, the exposure of the submarine cable laid under the seabed, and the increase in the suspended span of the submarine cable, which will have an adverse impact on the structural safety of the wind turbine and the operation and maintenance of the wind farm. In order to reduce the harm of local scouring, the existing treatment method is mainly to suppress the formation of local scouring. The specific measures taken are to arrange riprap, sandbags, etc. around the pile foundation of the wind turbine to reduce the degree of erosion of water flow around the pile foundation and protect the pile foundation and submarine cable safety. However, protective measures such as riprap and sandbags cannot provide targeted protection for the submarine cable of the wind turbine, and large-scale, non-targeted excessive protection will cause a waste of engineering costs. In addition, the stability of protective measures such as riprap and sandbags is also poor. They will move under the action of hydraulics, causing secondary scouring, and cannot further reduce the risk of large-scale exposure of submarine cables.

[0047] This embodiment provides a scour protection device for an offshore wind turbine transmission cable to solve the above problem. The scour protection device for an offshore wind turbine transmission cable is mainly used for unprotected pile foundations 1 that are subject to local scours, pile foundations 1 that have been scour-protected but have failed, and the surrounding areas of the cable.

[0048] The scour protection device of the offshore wind turbine transmission submarine cable includes a group of stone bags to protect the submarine cable, and the group of stone bags to protect the submarine cable includes a supporting stone bag group, a limiting stone bag group and a fixed stone bag group formed by a plurality of stone bags. The supporting stone bag group is arranged in the suspended area of ​​the submarine cable, and the supporting stone bag group is located below the submarine cable to support the submarine cable. The limiting stone bag group is located in the suspended area, and the stone bags of the limiting stone bag group are located on both sides of the submarine cable to clamp the submarine cable. The submarine cable is located between the two stone bags. The limited space between the two stone bags can be used to limit the movement of the submarine cable to prevent the lateral movement of the submarine cable. The fixed stone bag group includes a suspended covering stone bag group and a ground-touching reinforcement stone bag group. The suspended covering stone bag group is located in the suspended area and above the submarine cable to compress the submarine cable, reduce the hydrodynamic amplitude of the submarine cable, and increase the stability of the stone bag below. The ground-contact reinforcement stone bag group is located in the ground-contact area of ​​the submarine cable. The ground-contact reinforcement stone bag group includes a T-shaped end stone bag group. The T-shaped end stone bag group includes a circumferentially arranged stone bag group and a compacted stone bag group. The circumferentially arranged stone bag group extends along the circumference of the concentric circle of the pile foundation 1. The compacted stone bag group is arranged above the submarine cable along the extension direction of the cable. The compacted stone bag group is vertically connected to the midpoint of the circumferentially arranged stone bag group, so that the circumferentially arranged stone bag group and the compacted stone bag group are arranged in a T shape, and the circumferentially arranged stone bag group is farther away from the pile foundation 1 than the compacted stone bag group. The T-shaped end stone bag group can avoid end scouring and sinking instability. First of all, compared with sandbags and riprap, stone bags have better stability, and through the reasonable planning and design of the above-mentioned stone bag group, secondary scouring can be suppressed to the greatest extent, preventing large-scale exposure of the submarine cable and protecting the submarine cable.

[0049] Optionally, the coverage of the ground contact area where the ground contact reinforcement stone bag group is located is a coverage area appropriately extended by 2-3 times the diameter of the stone bag along the buried section of the submarine cable.

[0050] Optionally, the center of the stone bag of the fixed stone bag group is located vertically above the submarine cable, that is, the center of the stone bag covers the submarine cable, which can ensure that the coverage area of ​​a single stone bag is maximized and prevent the submarine cable from jumping out of the stone bags on both sides of the limiting stone bag group.

[0051] Optionally, the scour protection device of the offshore wind turbine transmission cable also includes a pile-surrounding spoiler stone bag group formed by a plurality of stone bags, the pile-surrounding spoiler stone bag group includes a first stone bag group arranged along the outer wall curved surface of the pile foundation 1, and also includes a second stone bag group arranged circumferentially along the concentric circles of the pile foundation 1, and the second stone bag group is close to the first stone bag group.

[0052] Optionally, the distance from the edge of the spoiler bag group around the pile to the center of the pile foundation 1 is within the range of 2D-3D, and D is the diameter of the pile foundation 1. The arrangement can be the above-mentioned annular arrangement, and the annular shape does not need to be closed, and the surrounding coverage angle can be determined according to the degree of scouring on site.

[0053] Optionally, the design of the spoiler stone bag group around the pile can be arranged along the cable. If the direction along the cable is not along the direction of the rising and falling tides of the main tide, the stone bags can be arranged in the direction of the rising and falling tides of the main tide to completely cover the surrounding area of ​​the pile foundation 1.

[0054] Optionally, the area where the spoiler stone bag group around the pile is located includes the horseshoe vortex generation area in front of the pile foundation 1, disrupting the strong flow field structure around the cylinder, so that the horseshoe vortex in front of the pile cannot be fully developed. Optionally, the area where the spoiler stone bag group around the pile is located includes the lateral streamline contraction area of ​​the pile foundation 1, so that the lateral streamline contraction is blocked. Optionally, the area where the spoiler stone bag group around the pile is located includes the rear vortex shedding area of ​​the pile foundation 1, so that the rear tail vortex shedding is weakened, reducing the shear stress amplification effect of the bottom bed around the pile foundation 1, and then playing a role in inhibiting the development of local scour.

[0055] Optionally, the scour protection device for the offshore wind turbine transmission submarine cable also includes a backfill scour pit stone bag group formed by arranging multiple stone bags, and the backfill scour pit stone bag group is used to fill the scour pit so that the depth of the filled scour pit is less than the maximum preset scour depth. The backfill scour pit stone bag group can prevent the scour pit from continuously expanding and exposing the submarine cable, reduce the depth of the scour pit, promote siltation and sand fixation, and reduce the scour impact area.

[0056] Optionally, the backfilling stone bag group covers the edge area of ​​the protecting cable stone bag group. The protecting cable stone bag group is located along the cable, and the backfilling stone bag group is located on both sides of the cable, so that the backfilling stone bag group can play the role of fastening the protecting cable stone bag group from both sides.

[0057] Optionally, the top elevation of the backfill scouring pit stone bag group cannot be too high, and the highest elevation is flush with the surrounding seabed. Optionally, the top elevation of the backfill scouring pit stone bag group is flush with the top elevation of the protective submarine cable stone bag group.

[0058] Optionally, among the groups of stone bags for protecting submarine cables, the groups of stone bags for spoiling flow around piles and the groups of stone bags for backfilling pits, the elevations of the stone bags adjacent to each other are smoothly transitioned to prevent the stone bags from sliding away from the designed positions and thus rendering their protective functions ineffective.

[0059] Optionally, there is one layer of stone bags at the edge of the protection area where the submarine cable stone bag group, the pile spoiler stone bag group and the backfill pit stone bag group are located as a whole, and there is more than one layer of stone bags inside the protection area, that is, the number of layers of stone bags at the edge of the protection area is less than the number of layers of stone bags inside the protection area.

[0060] Optionally, the vertical projection of the protection area where the submarine cable stone bag group, the pile spoiler stone bag group and the backfill pit stone bag group are located as a whole is fan-shaped, ensuring the maximum coverage of the area along the submarine cable.

[0061] Optionally, the bottom layer of stone bags protecting the submarine cable stone bag group, the spoiler stone bag group around the pile and the backfill pit stone bag group are arranged closely to ensure that the bottom foundation will not loosen, which is conducive to fixing the position of the upper stone bags.

[0062] Optionally, all the stone bags of the backfill pit stone bag group are closely arranged so that adjacent stone bags can provide lateral resistance support to each other to prevent the slope from sliding.

[0063] Optionally, all the stone bags of the spoiler stone bag group around the pile are arranged closely to prevent the slope from sliding.

[0064] Optionally, the stone bags of each stone bag group can adjust their filling amount based on actual conditions while ensuring their stability, and their filling openings can be tightened after filling for use. Optionally, the maximum mesh size of the stone bag is in the range of 5 cm to 10 cm. Optionally, each stone bag is equipped with a lifting structure for secondary installation and unloading.

[0065] like Figure 1-Figure 6 As shown, in order to illustrate how to reasonably arrange stone bags around pile foundations 1 with different scouring degrees, the No. 1 submarine cable 2 in the figure represents a submarine cable with severe scouring degree, which is specifically manifested in that the submarine cable span distance is greater than the design specification, and scouring pits are formed along the submarine cable. The No. 2 submarine cable 3 is a submarine cable with a slight scouring degree but is strongly affected by hydrodynamics. Specifically, the submarine cable span length is less than the design specification, and there is only a short span at the wind turbine submarine cable outlet. However, under the action of hydrodynamics, the movement amplitude of the submarine cable is large, and fatigue damage is prone to occur.

[0066] The scour protection device for the offshore wind turbine transmission submarine cable No. 1 submarine cable 2 includes a first-layer stone bag group 4 and a second-layer stone bag group 5 for pile disturbance arranged around the pile foundation 1, as well as a first-layer stone bag group 6 for protecting the No. 1 submarine cable, a second-layer stone bag group 8 for protecting the No. 1 submarine cable, a third-layer stone bag group 10 for protecting the No. 1 submarine cable, and a fourth-layer stone bag group 11 for protecting the No. 1 submarine cable, and also includes a first-layer stone bag group 12 for backfilling the scour pit.

[0067] Among them, the first-layer stone bag group 4 of the pile surrounding flow disturbance is arranged in a ring around the pile foundation 1, and three arc stone bag groups are arranged radially, and the coverage range is 2-2.5 times the diameter of the pile foundation 1 in the axial direction. The second-layer stone bag group 5 of the pile surrounding flow disturbance is arranged above the first-layer stone bag group 4 of the pile surrounding flow disturbance, and is arranged close to the outer wall of the pile foundation 1. The second-layer stone bag group 5 of the pile surrounding flow disturbance includes two arc stone bag groups, and the annular coverage range and radial coverage range are both smaller than the first-layer stone bag group 4 of the pile surrounding flow disturbance. The upper stone bag and the lower stone bag are stacked alternately, and the upper stone bag covers the gap of the lower stone bag. The first-layer stone bag group 4 of the pile surrounding flow disturbance and the second-layer stone bag group 5 of the pile surrounding flow disturbance are both located below the submarine cable. The stone bags of the second-layer stone bag group 5 of the pile surrounding flow disturbance corresponding to the submarine cable position can support the submarine cable from below, and the stone bags on both sides can provide lateral support to the two stone bags to prevent displacement failure.

[0068] The first-layer stone bag group 6 for protecting the No. 1 submarine cable is arranged in close contact with the first-layer stone bag group 4 for the disturbance flow around the pile. The first-layer stone bag group 6 for protecting the No. 1 submarine cable is located in the area where the submarine cable is located and on the side of the first-layer stone bag group 4 for the disturbance flow around the pile away from the pile foundation 1. The three innermost stone bags of the first-layer stone bag group 6 for protecting the No. 1 submarine cable close to the pile foundation 1 are located below the submarine cable to support the submarine cable, and belong to the supporting stone bag group. The two stone bags close to the innermost three stone bags of the first-layer stone bag group 6 for protecting the No. 1 submarine cable are located on both sides of the submarine cable to fix the submarine cable, and belong to the limiting stone bag group. The two stone bags in the middle of the two stone bags are arranged in a single row of stone bags, both located above the submarine cable, and used to compress and fix the submarine cable, and belong to the fixing stone bag group. The four stone bags farthest from the pile foundation 1 of the first-layer stone bag group 6 for protecting the No. 1 submarine cable are arranged in a "T" shape, and belong to the T-shaped end stone bag group, which is used to prevent the end from scouring, sinking and instability.

[0069] The second-layer stone bag group 8 for protecting the No. 1 submarine cable is arranged in a triangular pattern, with more stone bags on the side close to the pile foundation 1 and fewer stone bags on the side far from the pile foundation 1. The second-layer stone bag group 8 for protecting the No. 1 submarine cable is arranged close to the second-layer stone bag group 5 for spoiling flow around the pile, and the three innermost stone bags belong to the supporting stone bag group, the two middle stone bags belong to the limiting stone bag group, and the outermost stone bag belongs to the fixing stone bag group.

[0070] The three-layer stone bag group 10 for protecting the No. 1 submarine cable is arranged close to the pile foundation 1. The three rows of stone bag groups are arranged in sequence along the cable, and each row of stone bag groups includes two stone bags, which are respectively located on both sides of the submarine cable to fix the submarine cable. The above six stone bags of the three-layer stone bag group 10 for protecting the No. 1 submarine cable belong to the limiting stone bag group, and another stone bag is located on the outermost side and belongs to the fixed stone bag group.

[0071] One of the stone bags of the four-layer stone bag group 11 for protecting the No. 1 submarine cable is located in the gap between the three outermost stone bags of the three-layer stone bag group 10 for protecting the No. 1 submarine cable and covers the submarine cable, belonging to the suspended covering stone bag group of the fixed stone bag group.

[0072] A layer of stone bag groups 12 for backfilling the pits are arranged in the pit areas on both sides of the No. 1 submarine cable 2. The layer of stone bag groups 12 for backfilling the pits are arranged on both sides of a layer of stone bag groups 6 for protecting the No. 1 submarine cable, and the arrangement method is a horizontal and tight arrangement.

[0073] The scour protection device for the offshore wind turbine transmission submarine cable of the No. 2 submarine cable 3 includes a first-layer stone bag group 7 for protecting the No. 2 submarine cable and a second-layer stone bag group 9 for protecting the No. 2 submarine cable. The first-layer stone bag group 7 for protecting the No. 2 submarine cable is arranged close to the pile foundation 1. The three inner stone bags close to the pile foundation 1 belong to the supporting stone bag group, the three stone bags far away from the pile foundation 1 belong to the T-shaped end stone bag group of the fixed stone bag group, and the two stone bags in the middle belong to the limiting stone bag group to fix the submarine cable from both sides. The second-layer stone bag group 9 for protecting the No. 2 submarine cable is arranged close to the pile foundation 1 in a triangular arrangement. The number of stone bags on the side close to the pile foundation 1 is large, and the number of stone bags on the side far away from the pile foundation 1 is small. The inner stone bag belongs to the limiting stone bag group, and the outer stone bag belongs to the suspended covering stone bag group of the fixed stone bag group. Optionally, the number of layers and arrangement of the stone bag group for protecting the submarine cable are arranged according to the on-site status of the submarine cable. If the span is small, the end can be directly protected by a "T" shape anti-scour after being fixed at the submarine cable touchdown point.

[0074] Optionally, the number of layers and arrangement of the stone bag group for protecting the submarine cable are selected according to the on-site status of the submarine cable. If the span height of the submarine cable is small, there is no need to provide inner support for the three stone bags, but instead an arrangement of two stone bags limiting the position and one stone bag covering the cable can be directly adopted.

[0075] Optionally, if the flow field around the pile foundation 1 is not sufficient to cause scouring around the pile foundation 1 , the group of spoiler stone bags around the pile may not be arranged.

[0076] Optionally, if there is no scouring pit along the submarine cable on site or the depth of the scouring pit is relatively shallow, the stone bag group for backfilling the scouring pit may not be arranged. If the depth of the scouring pit is relatively deep, a multi-layer stone bag group for backfilling the scouring pit may be adopted, and the top elevation of the stone bag group for backfilling the scouring pit is not higher than the topmost stone bag group for protecting the submarine cable.

[0077] It is understandable that in practical applications, it is first necessary to determine the shape of the submarine cable and whether the span length exceeds the preset value. Then, a layer of stone bags for protecting the submarine cable is arranged and placed. In the case of severe scouring, a layer of stone bags for the spoiler stone bags around the pile and a layer of stone bags for backfilling the scouring pit are arranged and placed in sequence. The stone bag closest to the pile foundation 1 of the stone bag group protecting the submarine cable provides support for the submarine cable and the adjacent stone bags. The stone bag on the second inner side fixes the submarine cable and fixes the contact point of the submarine cable. The stone bags on the outer side are used to cover the submarine cable. The outermost T-shaped end stone bag group is set to provide "T"-shaped anti-scouring protection for the end.

[0078] By setting a first-layer stone bag group 4 for disturbing flow around the pile and a second-layer stone bag group 5 for disturbing flow around the pile foundation 1, the flow field around the pile foundation 1 can be disturbed, so that it can no longer cause scouring around the pile foundation 1. By setting a first-layer stone bag group 6 for protecting the No. 1 submarine cable, a second-layer stone bag group 8 for protecting the No. 1 submarine cable, a third-layer stone bag group 10 for protecting the No. 1 submarine cable, a fourth-layer stone bag group 11 for protecting the No. 1 submarine cable, a first-layer stone bag group 7 for protecting the No. 2 submarine cable, and a second-layer stone bag group 9 for protecting the No. 2 submarine cable, the submarine cable affected by scouring can be effectively protected, the movement amplitude of the submarine cable can be limited, and the risk of fatigue damage to the submarine cable can be reduced. By setting a first-layer stone bag group 12 for backfilling the scouring pit that has been formed, the terrain along the submarine cable can be made relatively flat. In addition, the stone bag group also increases the roughness of the seabed, and the gaps between the stone bags can form a porous structure, reduce the bottom flow velocity, promote sedimentation, and prevent the continuous development of scouring.

[0079] The scour protection device of the offshore wind turbine transmission cable is provided with three groups of protective stone bags, namely, a group of spoiler stone bags around the piles, a group of protective cable stone bags and a group of backfilling stone bags, so as to specifically protect the seabed erosion and cable exposure caused by scour around the pile foundation 1 of the wind turbine. Due to the wrapping effect of the net bag on the outer layer of the stone bag, the stability of the stone bag is greater than the stability of a single stone when throwing stones. The close arrangement of the stone bags on the same layer in the stone bag group can utilize the mutual support between the stone bags, thereby increasing the stability of a single stone bag. The closely arranged stone bags can also increase the roughness of the seabed, which is conducive to reducing the flow rate of the bottom water flow and playing a role in promoting siltation and sand fixation. Compared with the protection methods such as throwing stones and sandbags in the prior art, the scour protection device of the offshore wind turbine transmission cable can effectively limit the movement of the cable under the action of water, and can especially effectively prevent the cable buried under the seabed from being exposed due to scour, thereby reducing the risk of damage to the cable due to secondary exposure. In addition, the scour protection device of the offshore wind turbine transmission cable avoids the waste and redundancy of engineering costs caused by large-scale, non-targeted excessive protection such as riprap and sandbags, which can reduce costs and increase efficiency.

[0080] In order to enable those skilled in the art to better understand the technical solution of this embodiment, the following will be explained in conjunction with the experiments carried out to discuss the effectiveness of the scour protection device for the offshore wind turbine transmission cable proposed in this embodiment.

[0081] The experimental water tank is 30m long and 1.5m wide. The physical experiment section is arranged in the middle of the water tank, with a total length of 10m. The core experiment section is as follows Figure 7As shown, the experimental section sand bed 13 has a height of 0.6m and a length of 6m. The sand bed 13 is paved with washed quartz sand. In addition, silt with a height of 0.2m and a length of 2.0m is laid upstream and downstream of the core experimental section, respectively. The purpose is to ensure sufficient silt supply along the incoming flow direction when conducting physical experiments. At the same time, a 1:15 gentle slope 14 is set at both ends of the experimental section to ensure that the incoming flow can smoothly transition to the core experimental section. The experimental fan foundation 15 is made of a smooth plexiglass tube with a diameter D of 0.15m. The water depth is set to 0.9m. The experimental coordinate system defines that the flume is defined as the y-axis along the way, and the initial water flow flows from the negative direction of the y-axis to the positive direction; the water depth direction is defined as the z-axis, whose zero point is located at the initial sand bed plane position, and the direction from the bottom of the water to the water surface is the positive direction of the z-axis. During the experiment, the velocity meter 16 measures the flow velocity outside the boundary layer in real time, and the laser terrain scanner 17 measures the scour depth and scour extension range around the experimental wind turbine foundation 15 in real time.

[0082] The experiment adopted the water flow intensity similarity criterion. In order to retain the asymmetry of the scouring degree of the pile column in the upstream and downstream directions, the water flow form adopted in the experiment was unidirectional flow. According to the calculation of the on-site hydrological conditions, the average flow velocity of the laboratory section was 0.55m / s. At this flow velocity, the shear stress of the sand bed 13 in the experimental section was about 3 times the critical starting shear stress of the sediment, so the scouring type of this experiment was moving bed scouring.

[0083] The initial layout of the experimental scanned terrain is as follows Figure 8 Before the scouring experiment, the sand bed 13 was leveled and the submarine cables were buried. The No. 1 submarine cable 2 was located in the negative area of ​​the y-axis, and the No. 2 submarine cable 3 was located in the positive area of ​​the y-axis. The two submarine cables extended from the wind turbine to the bottom of the seabed. Most of the submarine cable model was buried under the seabed without large-scale exposure.

[0084] Subsequently, riprap protection was arranged according to the results of on-site terrain survey. The riprap protection at this time was a traditional riprap protection method, that is, the riprap was unevenly distributed and higher than the surrounding seabed.

[0085] The topography after 2 hours of scouring is as follows Fig. 9As shown. Under the action of unidirectional flow scouring, scouring mainly occurs in the back direction of the pile column, exposing the No. 2 submarine cable 3 to form a long-distance suspended span; the pile column is slightly scoured in the front direction of the flow, and the No. 1 submarine cable 2 is only slightly exposed, without forming a long-distance suspended span. The impact of scouring is relatively minor, but there is still a risk of continuous exposure, and scouring protection is also required to ensure its safety in place. At this time, the negative impact of the submarine cable around the scouring pile foundation cannot be ignored, and it is necessary to take appropriate scouring protection measures. From the above experimental results, it can be seen that if the traditional riprap method is used, that is, the riprap is unevenly distributed and higher than the surrounding seabed plane, severe edge scouring will occur, forming a larger scouring pit in the back direction of the pile column, thereby exposing a larger range of submarine cables, forming a long-distance suspended span, and vibrating violently under the action of water flow, increasing the risk of submarine cable damage.

[0086] At this time, the stone bags are arranged according to the arrangement method of the scouring protection device of the offshore wind turbine transmission cable described above in this embodiment, and then the scouring is continued for 6 hours. Fig.10 As shown, the scanned topographic map was obtained 8 hours after the experiment.

[0087] The experimental results show that: the No. 1 submarine cable 2, which had been slightly scoured before, was buried under the influence of the stone bag group to slow down the water flow. The in-situ state is safe. The stone bags located above the riprap pile remain stable. There is a small amount of silt accumulation between the gaps of the stone bag group. Due to the support between the stone bag groups, there is no risk of sliding of the stone bags. The No. 2 submarine cable 3 is stable in its in-situ state. Due to the support and fixation of the stone bag group, the No. 2 submarine cable 3 after treatment is no longer affected by the water flow and vibrates. The area along the submarine cable continues to accumulate silt, and some stone bags have been completely buried by silt. This state shows that the area along the submarine cable has been effectively protected, and the dangerous in-situ state has been changed to a safe in-situ state. For areas where scouring pits have been formed, the seabed elevation has rebounded due to the significant effect of the stone bag group in backfilling the scouring pit to promote siltation and fix sand, and the surrounding areas along the submarine cable have also been effectively protected.

[0088] In summary, the scour protection device for the offshore wind turbine transmission cable of this embodiment is proven to be effective and can be applied to actual engineering projects. It has important reference significance and engineering value for protecting the submarine cable under secondary scour caused by the traditional riprap method.

[0089] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. The scour protection device for the offshore wind turbine transmission cable is characterized in that: include: A group of stone bags for protecting submarine cables comprises a supporting stone bag group, a limiting stone bag group and a fixed stone bag group formed by a plurality of stone bags arranged. The supporting stone bag group is arranged in a suspended area of ​​the submarine cable, the supporting stone bag group is located below the submarine cable to support the submarine cable, the limiting stone bag group is located in the suspended area, the stone bags of the limiting stone bag group are located on both sides of the submarine cable to clamp the submarine cable, the fixed stone bag group comprises a suspended covering stone bag group and a ground-contacting reinforcement stone bag group, the suspended covering stone bag group is located in the suspended area and above the submarine cable to compress the submarine cable, the ground-contacting reinforcement stone bag group The reinforcement stone bag group is located in the ground contact area of ​​the submarine cable, the ground contact reinforcement stone bag group includes a T-shaped end stone bag group, the T-shaped end stone bag group includes a circumferentially arranged stone bag group and a compacting stone bag group, the circumferentially arranged stone bag group extends along the circumference of the concentric circles of the pile foundation (1), the compacting stone bag group is arranged above the submarine cable along the extension direction of the submarine cable, and the compacting stone bag group is vertically connected to the midpoint of the circumferentially arranged stone bag group so that the circumferentially arranged stone bag group and the compacting stone bag group are arranged in a T-shape, and the circumferentially arranged stone bag group is farther away from the pile foundation (1) than the compacting stone bag group.

2. The scour protection device for the offshore wind turbine outgoing cable according to claim 1 is characterized in that: The center of the stone bag of the fixed stone bag group is located vertically above the submarine cable.

3. The scour protection device for the offshore wind turbine outgoing cable according to claim 1 is characterized in that: It also includes a pile-surrounding spoiler stone bag group formed by arranging a plurality of the stone bags, the pile-surrounding spoiler stone bag group including a plurality of first stone bag groups arranged along the outer wall curved surface of the pile foundation (1), and a plurality of second stone bag groups arranged along the circumference of the concentric circles of the pile foundation (1), the second stone bag group being close to the first stone bag group.

4. The scour protection device for the offshore wind turbine transmission cable according to claim 3 is characterized in that: The area where the spoiler stone bag group around the pile is located includes the horseshoe vortex generation area in front of the pile foundation (1); And / or, the area where the spoiler stone bag group around the pile is located includes the lateral streamline contraction area of ​​the pile foundation (1); and / or, the area where the spoiler stone bag group around the pile is located includes the rear vortex shedding area of ​​the pile foundation (1); And / or, the vertical projection of the spoiler stone bag group around the pile covers part of the vertical projection of the area where the submarine cable is located.

5. The scour protection device for the offshore wind turbine outbound cable according to claim 3 or 4, characterized in that: It also includes a backfill pit stone bag group formed by arranging a plurality of the stone bags, and the backfill pit stone bag group is used to fill the pit so that the depth of the filled pit is less than a maximum preset scouring depth.

6. The scour protection device for the offshore wind turbine transmission cable according to claim 5 is characterized in that: The backfill pit stone bag group covers the edge area of ​​the protective sea cable stone bag group.

7. The scour protection device for the offshore wind turbine transmission cable according to claim 5 is characterized in that: The top elevation of the backfilled scouring pit stone bag group is at most flush with the surrounding seabed; And / or, the top elevation of the backfill pit stone bag group is at most flush with the top elevation of the protective submarine cable stone bag group.

8. The scour protection device for the offshore wind turbine transmission cable according to claim 5, characterized in that: The elevations of the adjacent stone bags in the cable protection stone bag group, the pile surrounding spoiler stone bag group and the backfill pit stone bag group are smoothly transitioned; And / or, the stone bags at the edge of the protection area where the protective sea cable stone bag group, the pile spoiler stone bag group and the backfill pit stone bag group are located as a whole are one layer, and the stone bags inside the protection area are more than one layer.

9. The scour protection device for the offshore wind turbine transmission cable according to claim 5, characterized in that: The vertical projection of the protection area where the protective cable stone bag group, the pile surrounding spoiler stone bag group and the backfill pit stone bag group are located as a whole is fan-shaped.

10. The scour protection device for the offshore wind turbine transmission cable according to claim 5, characterized in that: The stone bags at the bottom of the protective cable stone bag group, the pile surrounding spoiler stone bag group and the backfill pit stone bag group are closely arranged; And / or, all the stone bags of the backfill pit stone bag group are tightly arranged; And / or, all the stone bags of the spoiler stone bag group around the pile are tightly arranged.

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