An anchor-prevention device and method for a landing-end submarine cable

Abstract

The application provides an anchor damage prevention device and method for a submarine cable, wherein the method comprises the following steps: S1, determining the side length L of the anchor damage prevention pile according to the diameter d of the submarine cable to be protected; S2, oppositely arranging a plurality of anchor damage prevention piles on both sides of the submarine cable to be protected; S3, determining the spacing Lx between the anchor damage prevention piles in the direction perpendicular to the water flow and the spacing Ly between the anchor damage prevention piles in the direction along the water flow according to the side length L of the anchor damage prevention pile; and S4, adjusting the positions of the plurality of anchor damage prevention piles according to the spacing Lx between the anchor damage prevention piles in the direction perpendicular to the water flow and the spacing Ly between the anchor damage prevention piles in the direction along the water flow. The application can effectively avoid the damage of the submarine cable caused by the ship anchor.

Description

Technical Field

[0001] This invention relates to the field of submarine cable protection technology, and in particular to a device and method for preventing anchor damage to submarine cables at the mud-entry end. Background Technology

[0002] Due to operational needs, work or maintenance vessels are frequently moored near wind turbines, and the anchors of these vessels are highly susceptible to damaging submarine cables during movement. Currently, there are very few devices to prevent anchor damage to submarine cables at the mud-end point. In most wind farms, the submarine cables extend directly from the wind turbine and are laid on the seabed. Existing methods mainly rely on warnings, issuing an alarm when a vessel approaches the wind turbine. However, in reality, workers often ignore these warnings because the warning devices only detect proximity; they trigger an alarm regardless of whether the cable is hooked. The anchors of moored vessels may not necessarily hook the cable, leading to crew negligence.

[0003] For the protection of submarine cables in special sections or exposed sections with shallow burial depth, methods such as throwing stones, covering with sandbags, and placing concrete chain blocks are mostly used. These methods are easily affected by hydrology and have little effect on the connection and protection of ship anchors, and cannot meet the requirements of high-quality and long-term submarine cable protection.

[0004] Rockfill protection: For areas with hard seabed geology where burial protection is not feasible, the method used is to protect submarine cables by rockfill protection to prevent damage. This involves placing appropriately graded crushed stones around the cable using specific construction equipment to form a protective layer. This is currently the most widely used method. When implementing rockfill protection, several variables must be considered: variations in the thickness of the rockfill layer, characteristics of the stones, burial shape, burial range, anchor intrusion by anchors of different weights, and the initial intrusion velocity of the anchors during the anchor intrusion process. While this protection method can effectively keep the pipeline stationary, preventing scouring and suspension, and protecting the pipeline from human factors such as anchors, it is also relatively low-cost and simple to construct. However, if measures are not taken properly and the pipeline is not adequately restrained, it will rub against the surrounding stones, causing more severe damage. Furthermore, water can enter through the gaps between the stones, creating flow that continuously scours out fine sand or stones, ultimately rendering the protection ineffective. Simultaneously, scouring can occur around the edges of the rockfill layer, leading to instability and deformation.

[0005] Supported fixed protection: This type of device typically uses some kind of apparatus or structure to secure the submarine cable underwater. Generally speaking, this type of fixation is quite effective; however, if underwater drilling or piling is involved, it greatly increases costs and is difficult to use on a large scale. It is also difficult to secure the cable in the face of severe storm surges, and is rarely used in practice. The non-piling method, as shown in the image, uses silt to hold the cable in place. This method has very poor fixation effectiveness and will fail in fast-flowing water or after a short period of operation.

[0006] Utility model patent CN216056258U discloses an insertable submarine cable anti-anchoring device, comprising a U-shaped protective shell body. The lower inner side of the protective shell body has two anti-settlement resistance baffles, with a gap larger than the diameter of the submarine cable between the two baffles. The upper part of the protective shell body has drainage holes, and the lower ends of both sides of the protective shell body have insertion parts for insertion into the seabed. However, this insertable submarine cable anti-anchoring device relies on silt to hold the cable in place, and it fails when the water flow is fast or the operation time is slightly longer. Summary of the Invention

[0007] The purpose of this invention is to address the deficiencies in the prior art by providing a device and method for preventing anchor damage to submarine cables at the mud-entry end, which can effectively prevent ship anchors from damaging submarine cables.

[0008] To achieve the above objectives, the present invention provides a device for preventing anchor damage to submarine cables at the mud entry point, comprising a plurality of anchor damage prevention piles arranged opposite each other on both sides of the submarine cable to be protected. The adjacent anchor damage prevention piles arranged perpendicular to the water flow direction are connected by a connecting rope. Each anchor damage prevention pile has a cavity for placing materials, and the side wall of each anchor damage prevention pile is provided with a plurality of resistance-increasing components.

[0009] Optionally, the anti-anchoring pile is provided with a plurality of connecting columns, and the connecting rope is connected to the anti-anchoring pile through the connecting columns.

[0010] Optionally, the anti-anchoring pile includes a pile body and a pile cap, the pile cap being connected to the pile body, and the receiving cavity being located within the pile body.

[0011] Optionally, the bottom of the pile body is provided with several drainage holes, and the pile cover is provided with several vent holes.

[0012] This invention also provides a method for preventing anchor damage to submarine cables at the mud-entry end, comprising the following steps:

[0013] S1. Determine the side length L of the anchorage protection pile based on the diameter d of the submarine cable to be protected;

[0014] S2. Install several anchorage protection piles on both sides of the submarine cable to be protected.

[0015] S3. Based on the side length L of the anchorage prevention piles, determine the spacing Lx between the anchorage prevention piles perpendicular to the water flow direction and the spacing Ly between the anchorage prevention piles along the water flow direction.

[0016] S4. Adjust the position of several anchorage prevention piles according to the spacing Lx between the anchorage prevention piles perpendicular to the water flow direction and the spacing Ly between the anchorage prevention piles along the water flow direction.

[0017] This invention utilizes the aforementioned method for preventing anchor damage to submarine cables by setting up obstacles on both sides of the submarine cable to prevent the anchor from getting close to it. This prevents the cable from being hooked. At the same time, considering the impact of the anchor damage prevention piles on the flow field, the spacing between the anchor damage prevention piles is reasonably set to minimize their adverse effects. This also effectively reduces the erosion of the submarine cable by mud and sand around it, providing long-term and effective protection against anchor damage while also taking into account cost and construction technology.

[0018] Optionally, in S1, the formula for determining the side length L of the anchorage prevention pile is:

[0019]

[0020] Optionally, in step S3, the formula for determining the spacing Lx between the anti-anchorage piles perpendicular to the water flow direction is:

[0021] Lx = 10L 。

[0022] Optionally, in S3, the formula for determining the spacing Ly between the joint prevention anchor piles is:

[0023] Ly = 15L

[0024] Optionally, before step S1, step S0 is also included: determining the reference range of the submarine cable diameter based on the resistance encountered by the anti-anchor pile when it is hooked in the mud and sand, and judging whether the diameter d of the submarine cable to be protected is within the range.

[0025] If the diameter of the submarine cable to be protected is too small, take the minimum value in the reference range of submarine cable diameter for subsequent steps; if the diameter of the submarine cable to be protected is too large, take the maximum value in the reference range of submarine cable diameter for subsequent steps.

[0026] Optionally, in step S0, the resistance to the movement of the anchor pile in the mud and sand is determined by the following formula:

[0027]

[0028] Where C refers to the resistance coefficient in the sediment, ρ is the density of the sediment, v is the velocity of movement, and s is the cross-sectional area of ​​the anchorage prevention pile.

[0029] The reference range for submarine cable diameter is obtained based on the cross-sectional area of ​​the anchorage protection piles.

[0030] Beneficial effects:

[0031] This invention utilizes the aforementioned method for preventing anchor damage to submarine cables by setting up obstacles on both sides of the submarine cable to prevent the anchor from getting close to it. This prevents the cable from being hooked. At the same time, considering the impact of the anchor damage prevention piles on the flow field, the spacing between the anchor damage prevention piles is reasonably set to minimize their adverse effects. This also effectively reduces the erosion of the submarine cable by mud and sand around it, providing long-term and effective protection against anchor damage while also taking into account cost and construction technology. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0033] Figure 1 This is a top view of the distribution of anchor-prevention piles in the anchor-prevention method for submarine cables at the mud-entry end disclosed in this invention.

[0034] Figure 2 This is a diagram showing the change in the scouring depth of the anchorage prevention piles installed along the water flow direction in the anchorage prevention method for submarine cables at the mud-entry end disclosed in this invention.

[0035] Figure 3 This diagram illustrates the variation in the scouring depth of the anchorage prevention piles installed perpendicular to the water flow direction in the anchorage prevention method for submarine cables at the mud-entry end disclosed in this invention.

[0036] Figure 4 This is a schematic diagram showing the scouring length and scouring width of the anchorage prevention piles installed along the water flow direction and the anchorage prevention piles installed perpendicular to the water flow direction in the anchorage prevention method for submarine cables at the mud entry end disclosed in this invention.

[0037] Figure 5 This is a diagram showing the variation of the scouring length of the anchorage prevention piles installed along the water flow direction and the scouring width of the anchorage prevention piles installed perpendicular to the water flow direction in the anchorage prevention method for submarine cables at the mud entry end disclosed in this invention.

[0038] Figure 6 This is a diagram showing the variation of the scouring width of the anchorage prevention piles installed along the water flow direction and the scouring length of the anchorage prevention piles installed perpendicular to the water flow direction in the anchorage prevention method for submarine cables at the mud entry end disclosed in this invention.

[0039] Figure 7 This is a structural diagram of the anchor-prevention pile in the anti-anchor-damage device for submarine cables at the mud-entry end disclosed in this invention, taken from a first-view perspective.

[0040] Figure 8 This is a structural diagram from a second perspective of the anti-anchoring device for submarine cables at the mud entry end disclosed in this invention.

[0041] Figure 9 This is a third-view structural diagram of the anti-anchoring device for submarine cables at the mud entry end disclosed in this invention.

[0042] Figure label:

[0043] 1. Submarine cable to be protected; 2. Anti-anchor pile; 3. Pile body; 4. Drainage hole; 5. Pile cover; 6. Vent hole; 7. Receiving cavity; 8. Connecting column; 9. Resistance increasing component; 10. Connecting rope; 11. Fan.

[0044] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0045] See Figure 1 In actual deployment, several anti-anchor piles 2 are located in two positions: along the water flow direction and perpendicular to the water flow direction.

[0046] The existing literature, "Sacrificial piles as a countermeasure against local scouraround underwater pipelines," by Forough Raeisi, Seyed Mohammad Ali Zomorodian, Masih Zolghadr, and Hazi Mohammad Azamathulla, in *Water Science and Engineering*, Volume 17, Issue 2, 2024, Pages 187-196, ISSN 1674-2370, records the following:

[0047] For anchorage prevention piles installed along the direction of water flow, see [link / reference]. Figure 2 The horseshoe vortex on the front side of the rear pile can be damaged due to insufficient space in front of the pile. Only when the gap ratio is greater than 3D (D is the diameter of the pile, which in this invention is equivalent to the side length L of the anti-anchorage pile) will the influence of the upstream wake vortex be reduced, causing a horseshoe vortex to appear in front of the downstream pile. When the gap ratio is 2D, the front pile has the largest scour depth, becoming 1.3D. After it exceeds 10D, the scour depth is the same as that of a single pile. The scour depth of the rear pile is always smaller. Before the ratio is 5D, the scour depth increases, and after 5D, the scour depth decreases. To ensure the stability of the pile, the surrounding scour depth should be as small as possible. To reduce the impact on the submarine cable, there should ideally be no scour pit between the two piles (point B).

[0048] For anchorage prevention piles installed perpendicular to the water flow direction, see [link / reference]. Figure 3When the spacing ratio is 0, the pile can be considered as a single unit, and the scouring depth is also greater at 1.9S. When the spacing ratio is 7, the scouring depth in front of the pile is the same as that of a single pile. Between the two piles, when the spacing ratio is 2, the scouring depth is the same as that of a single pile, and then it continuously decreases. When the ratio is 10, there is no scouring between the two piles. Scouring pits around the pile and scouring pits in the middle will affect its stability.

[0049] See Figure 4-6 The scour range varies with different spacing and pile diameter ratios. Figure 4 The left side of the image shows anti-anchoring piles installed along the direction of water flow, while the right side shows anti-anchoring piles installed perpendicular to the direction of water flow.

[0050] For anti-anchorage piles installed along the water flow direction, the scour length Lx increases with the spacing ratio, and the scour width Ly reaches its maximum at 0.5, which is 3D.

[0051] For anti-anchorage piles installed perpendicular to the water flow direction, the scour length Ly continuously increases, and the scour width Lx reaches a maximum of 6D when it is 0.5.

[0052] In summary, this invention requires the installation of anti-anchorage piles 2 around the submarine cable 1 to be protected by the wind turbine 11. It is essential to ensure that the submarine cable 1 is not subjected to excessive scouring and that the piles themselves remain stable. When the piles are installed along the direction of the water flow, the scouring between the two anti-anchorage piles 2 must be minimal. At least when the spacing ratio is greater than 10, there will be no scouring depth between the piles 2. After a spacing ratio greater than 10D, the scouring depth of both the front and rear anti-anchorage piles 2 continuously decreases, reaching its minimum at 15D. When the piles are installed perpendicular to the water flow direction in the same row, the scouring width Lx must not touch the submarine cable 1 to be protected. The maximum scouring depth is 5D at 0.5D. Considering the scouring depth, it reaches its minimum after a spacing ratio greater than 10D, and the scouring depth between the two anti-anchorage piles 2 also disappears.

[0053] Considering that when the anchor is pulled to the steel cable, the longer the steel cable, the shorter the distance the anchor-damage prevention pile 2 will travel in the silt, which is less conducive to restricting the ship's movement, the spacing between the anchor-damage prevention piles 2 along the water flow direction is preferably 15D, and the spacing between the anchor-damage prevention piles 2 perpendicular to the water flow direction is preferably 10D.

[0054] This invention mitigates scouring below the submarine cable 1 by placing anti-anchorage piles 2 upstream of the cable to be protected. The presence of the anti-anchorage piles 2 affects downstream water flow, reducing flow velocity and creating wake vortices. If the distance between the anti-anchorage piles 2 and the submarine cable 1 is properly designed, not only can the scouring below the cable 1 be reduced, but the sediment carried by the wake vortex will also fill the scouring hole, reducing the depth of the scouring hole or burying the cable 1.

[0055] By installing cylindrical or cubic anchorage protection piles 2, local scouring around the submarine cable 1 to be protected can be reduced under clear water conditions. The size of the anchorage protection piles 2, the spacing (Sp) between the anchorage protection piles 2, and the distance (Xp) between the submarine cable 1 to be protected and the anchorage protection piles 2 are effective variables for reducing scouring around the submarine cable 1 to be protected. The existing literature indicates that, with other variables being equal, the scouring reduction effect of cubic anchorage protection piles 2 is better than that of cylindrical anchorage protection piles 2. Xp = 40d is the optimal installation distance for the anchorage protection piles 2 (d is the diameter of the submarine cable 1 to be protected). This distance allows the mud and sand scourled from the anchorage protection piles 2 to cover the submarine cable 1 to be protected, filling the scour pit.

[0056] Therefore, this invention not only needs to design the installation location of the anti-anchorage pile 2, but also needs to determine the size of the anti-anchorage pile 2. The size of the anti-anchorage pile 2 determines the extent to which the ship's movement is restricted; the larger the anti-anchorage pile 2 is, the greater the force required to hook it. However, if the designed anti-anchorage pile 2 is too large, it will not only be unfavorable for placement, installation, and subsequent replacement, but it will also conflict with the previously determined spacing.

[0057] Most of the submarine cables to be protected 1 have a diameter between 30 and 40 centimeters. In order for the mud and sand washed out by the front anti-anchor piles 2 to cover the submarine cable to be protected 1, the distance between the two should be 40d. The anti-anchoring device should be installed on both sides of the submarine cable to be protected 1, that is, the spacing of the anti-anchor piles 2 along the direction of water flow is 80d, and the actual spacing is between 24 and 32 meters. At the same time, considering that the spacing between the anti-anchor piles 2 along the direction of water flow is best at 15D, most of the anti-anchor piles 2 are designed to be 2 meters long to achieve the ideal situation.

[0058] Based on the aforementioned existing literature, the design principle of this invention is as follows: the presence of the anti-anchorage pile 2 alters the original flow field state, causing changes in the flow around the submarine cable 1 to be protected and the anti-anchorage pile 2. Regarding the arrangement of the anti-anchorage pile 2, firstly, the scouring situation around the anti-anchorage pile 2 must be considered. To make the anti-anchorage pile 2 more stable, the scouring around it should be minimized. Secondly, the impact of placing the anti-anchorage pile 2 on the submarine cable 1 to be protected must be considered. The presence of the anti-anchorage pile 2 may exacerbate the scouring near the submarine cable 1 to be protected, leading to more severe damage due to the bending motion of the submarine cable 1. Considering these two points, the rational placement of the anti-anchorage pile 2 is crucial.

[0059] Layout: The spacing between the anti-anchor piles 2 along the water flow direction is 15D, and the spacing between the anti-anchor piles 2 perpendicular to the water flow direction is 10D (D is the diameter of the pile, which is equivalent to the side length L of the anti-anchor pile 2 in this invention), which is 2m here. This side length is applicable to most cases.

[0060] Example 1:

[0061] See Figure 1-6A method for preventing anchor damage to submarine cables at the mud-entry end according to an embodiment of the present invention includes the following steps:

[0062] S1. Determine the side length L of the anchorage protection pile 2 based on the diameter d of the submarine cable 1 to be protected;

[0063] S2. Install several anchorage prevention piles 2 on both sides of the submarine cable 1 to be protected;

[0064] S3. Based on the side length L of the anchorage prevention pile 2, determine the spacing Lx between the anchorage prevention piles 2 perpendicular to the water flow direction and the spacing Ly between the anchorage prevention piles 2 along the water flow direction.

[0065] S4. Adjust the position of several anti-anchor piles 2 according to the spacing Lx between the anti-anchor piles 2 perpendicular to the water flow direction and the spacing Ly between the anti-anchor piles 2 along the water flow direction.

[0066] This invention utilizes the aforementioned method for preventing anchor damage to submarine cables by setting up obstacles on both sides of the submarine cable to prevent the anchor from getting close to it. This prevents the cable from being hooked. At the same time, considering the impact of the anchor damage prevention piles on the flow field, the spacing between the anchor damage prevention piles is reasonably set to minimize their adverse effects. This also effectively reduces the erosion of the submarine cable by mud and sand around it, providing long-term and effective protection against anchor damage while also taking into account cost and construction technology.

[0067] See Figure 1-6 In some embodiments of the present invention, in step S1, the formulas for determining the side length L of the anti-anchor pile 2, the spacing Lx between the anti-anchor piles 2 perpendicular to the water flow direction, and the spacing Ly between the anti-anchor piles 2 along the water flow direction are as follows:

[0068]

[0069] Lx = 10L

[0070] Ly = 15L

[0071] See Figure 1-6 In some embodiments of the present invention, before step S1, step S0 is included: determining the reference range of the submarine cable diameter based on the resistance encountered by the anti-anchor pile 2 when it is hooked in the mud and sand, and judging whether the diameter d of the submarine cable 1 to be protected is within the range.

[0072] If the diameter of the submarine cable 1 to be protected is too small, take the minimum value in the reference range of submarine cable diameter for subsequent steps; if the diameter of the submarine cable 1 to be protected is too large, take the maximum value in the reference range of submarine cable diameter for subsequent steps.

[0073] Referring to the figure, in some embodiments of the present invention, in step S0, the resistance to the movement of the anti-anchor pile 2 in the mud and sand is determined by the following formula:

[0074]

[0075] Where C refers to the resistance coefficient in the sediment, ρ is the density of the sediment, v is the velocity of movement, and s is the cross-sectional area of ​​the anchorage prevention pile 2.

[0076] Considering that the diameter of the submarine cable to be protected is too small or too large, resulting in the side length of the stakes being too small or the spacing being too large, an effective range must be determined.

[0077] The vessels around the wind turbine are mostly maintenance and research vessels, typically small in size, weighing between 50 and 200 tons. These vessels are mostly moving with the ocean current or moving slowly. Using the kinetic energy theorem F = ma, where m is the mass of the vessel and a is the acceleration, an approximate acceleration value can be obtained from the time t it takes for the vessel's initial velocity to become zero (a = v / t). The calculated force generated by the hooking device is between 10,000 N and 50,000 N. Based on the formula for the resistance F experienced by the device as it is hooked in the mud and sand:

[0078]

[0079] Where C refers to the resistance coefficient in the sediment, ρ is the density of the sediment, v is the velocity of movement, and s is the cross-sectional area of ​​the anchorage prevention pile 2.

[0080] Based on the cross-sectional area of ​​the anchorage protection pile 2, the side length L of the anchorage protection pile 2 is found to be in the range of 1.5m-4m, and the reference range for the diameter of the submarine cable is 0.3-0.75m. Submarine cables 1 to be protected within this range can directly use the above formula to calculate the placement parameters, and the diameter of most submarine cables 1 to be protected is also within this range. If the diameter of the submarine cable 1 to be protected is too small, the minimum value in the reference range of the diameter of the submarine cable 1 to be protected is taken for subsequent steps; if the diameter of the submarine cable 1 to be protected is too large, the maximum value in the reference range of the diameter of the submarine cable 1 to be protected is taken for subsequent steps.

[0081] Example 2:

[0082] See Figure 1 and Figure 7-9 According to another embodiment of the present invention, a device for preventing anchor damage to a submarine cable at the mud entry end includes the aforementioned anchor damage prevention pile 1. The adjacent anchor damage prevention piles 1 arranged perpendicular to the water flow direction are connected by a connecting rope 10. The anchor damage prevention pile 1 is provided with a receiving cavity 7 for placing materials. The side wall of the anchor damage prevention pile 1 is provided with a plurality of resistance increasing components 9.

[0083] See Figure 7-9 In some embodiments of the present invention, the anti-anchor pile 1 is provided with a plurality of connecting posts 8, and the connecting rope 10 is connected to the anti-anchor pile 1 through the connecting posts 8.

[0084] See Figure 7-9In some embodiments of the present invention, the anti-anchoring pile 1 includes a pile body 3 and a pile cover 5, the pile cover 5 is connected to the pile body 3, and the receiving cavity 7 is disposed inside the pile body 3.

[0085] See Figure 7-9 In some embodiments of the present invention, the bottom of the pile body 3 is provided with a plurality of drainage holes 4, and the pile cover 5 is provided with a plurality of vent holes 6.

[0086] A large number of stones are placed inside the anchorage protection pile 2 as counterweights. These piles are then placed in the sea at predetermined locations, positioned on both sides of the submarine cable 1 to be protected. When the anchor sinks to the seabed and begins to move, it will first hook onto the connecting rope 10 upon approaching the submarine cable 1, causing the anchorage protection pile 2 to move as well. However, the immense weight of the anchorage protection pile 2 itself, along with the surrounding structure, will exert greater resistance on the seabed, preventing further movement of the anchor. This also serves as a warning to the crew that they are too close to the submarine cable and to allow for timely reaction. The connecting rope 10 is a steel cable.

[0087] The anti-anchor pile 2 is a cubic structure with several drag-increasing components 9 arranged on its four sides to increase resistance when moving through silt. The drag-increasing components 9 are similar in shape to ship anchors. The upper part is a removable pile cover 4, which has several vent holes 6. The pile cover 4 is connected to the pile body 3 by bolts. The purpose of the vent holes 6 is to facilitate the discharge of internal gas when the device is placed underwater, thereby reducing buoyancy. Several drainage holes 4 are also designed on the bottom surface of the pile body 3 to automatically drain internal water when it is pulled out of the sea for replacement of rocks or maintenance. Four connecting posts 8 are provided on each of the two opposite sides of the pile body for the connecting rope 10 to pass through.

Claims

1. A method of preventing anchor damage to a land end of a submarine cable, the method comprising: The application relates to a seabed anchor damage prevention device for a cable, which comprises a plurality of anchor damage prevention piles arranged oppositely on both sides of the cable to be protected, and connecting ropes arranged between adjacent anchor damage prevention pile devices and perpendicular to the water flow direction, wherein the anchor damage prevention piles are provided with containing cavities for placing materials, the side walls of the anchor damage prevention piles are provided with a plurality of resistance increasing members, the anchor damage prevention piles are provided with a plurality of connecting columns, the connecting ropes are connected with the anchor damage prevention piles through the connecting columns, the anchor damage prevention piles comprise pile bodies and pile covers, the pile covers are connected with the pile bodies, the containing cavities are arranged in the pile bodies, the bottom of the pile body is provided with a plurality of drainage holes, and the pile cover is provided with a plurality of exhaust holes. S1, determining the side length L of the anchor damage prevention pile according to the diameter d of the cable to be protected; S2, arranging a plurality of anchor damage prevention piles oppositely on both sides of the cable to be protected; S3, determining the interval Lx between the anchor damage prevention piles perpendicular to the water flow direction and the interval Ly between the anchor damage prevention piles along the water flow direction according to the side length L of the anchor damage prevention pile; S4, adjusting the positions of the plurality of anchor damage prevention piles according to the interval Lx between the anchor damage prevention piles perpendicular to the water flow direction and the interval Ly between the anchor damage prevention piles along the water flow direction.

2. A method of preventing anchor damage to a sea cable according to claim 1, characterised in that, In the S1, the formula for determining the side length L of the anchor damage prevention pile is: 。 3. The method of claim 1, wherein, In the S3, the formula for determining the interval Lx between the anchor damage prevention piles perpendicular to the water flow direction is: 。 4. The method of claim 1, wherein, In the S3, the formula for determining the interval Ly between the anchor damage prevention piles along the water flow direction is: 。 5. The method of claim 3, wherein, The step S1 further comprises determining the cable diameter reference range according to the resistance of the anchor damage prevention pile in the silt when being hooked and moved, and judging whether the diameter d of the cable to be protected is in the range. If the diameter of the cable to be protected is too small, the minimum value in the cable diameter reference range is taken for the subsequent steps; if the diameter of the cable to be protected is too large, the maximum value in the cable diameter reference range is taken for the subsequent steps.

6. A method of preventing anchor damage to a sea cable according to claim 5, characterised in that, The formula for determining the resistance of the anchor damage prevention pile in the silt when being hooked and moved is: ， Wherein C refers to the resistance coefficient in the silt, rho is the silt density, v is the moving speed, and s is the cross-sectional area of the anchor damage prevention pile. The cable diameter reference range is obtained according to the cross-sectional area of the anchor damage prevention pile.

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