A design method for secondary stabilization intervention of submarine cable by using a briquette structure

Abstract

This invention belongs to the field of submarine cable engineering technology and discloses a design method for secondary stability intervention of submarine cables using a block-type structure. The steps are as follows: 1) Based on the water flow velocity, wave height, and tidal cycle data of the target sea area, calculate the characteristic velocity of seabed flow under extreme conditions using empirical formulas; 2) Combine the cable diameter, self-weight, and flow parameters to calculate the hydrodynamic characteristics and in-situ stability of the cable and determine the required additional lateral resistance; 3) Analyze the hydrodynamic coefficient and inherent stability of the block-type structure through numerical simulation or physical experiments to quantify the lateral resistance that the block can provide to the cable; 4) Design the distribution spacing and total number of block distributions according to the cable stability requirements to form a preliminary layout scheme; 5) Improve the anti-slip performance by optimizing the size and shape of the block structure, and iteratively optimize the layout scheme based on the construction volume assessment to reduce engineering costs.

Description

Technical Field

[0001] This invention belongs to the field of submarine cable engineering technology, and relates to a design method for secondary stabilization intervention of submarine cables using a block-type structure, which aims to improve the stability and safety of submarine cables in complex marine environments. Background Technology

[0002] Submarine cables, as a crucial infrastructure for marine energy transmission, communication, and data transmission, are widely used in offshore wind power, transoceanic communication, and marine observation. However, submarine cables face complex marine environmental challenges during operation, including currents, waves, tides, and changes in seabed topography. These factors can lead to cable displacement, wear, fatigue, and even breakage, severely impacting their safety and service life.

[0003] Traditional methods for stabilizing submarine cables primarily rely on the cable's own weight and burial depth. For example, burying the cable at a certain depth below the seabed utilizes the soil's covering effect to reduce the direct impact of water currents and waves. However, this method has several limitations in practical applications: Limited burial depth: In some sea areas, complex seabed geological conditions (such as rock layers or hard soil) make deep burial difficult. Poor environmental adaptability: Under extreme environmental conditions (such as storms, typhoons, and strong currents), buried cables may still be subject to significant hydrodynamic loads, leading to displacement or damage. High construction difficulty: Deep burial of cables requires complex construction equipment and technology, resulting in high costs and long construction periods. Difficult maintenance: Once a cable fails, repair and maintenance of deeply buried cables are more difficult, potentially leading to prolonged service interruptions.

[0004] To overcome the shortcomings of traditional methods, several secondary stabilization intervention technologies have emerged in recent years, such as the use of counterweights, anchoring devices, or flexible protective structures. However, these technologies still face the following problems in practical applications: Lack of systematic design: Existing technologies are often designed only for single environmental conditions, lacking comprehensive consideration of complex marine environments. Insufficient stability: Some secondary stabilization structures struggle to provide sufficient anti-slip and anti-overturning capabilities under extreme environmental conditions. Poor economic efficiency: Some technologies require large amounts of materials and costly construction, making large-scale application difficult. Environmental impact: Some stabilization structures may adversely affect the marine ecosystem, such as damaging seabed habitats or hindering marine life activities.

[0005] Therefore, there is an urgent need for a systematic, cost-effective, and environmentally friendly method for secondary stabilization intervention of submarine cables to address the challenges of complex marine environments and ensure the long-term stability and safety of submarine cables. This invention addresses the above problems by proposing a design method for secondary stabilization intervention of submarine cables using a block-like structure. Through scientific calculation of the forces acting on the submarine cable and the block structure, and optimized design of the block structure's form and layout, the method significantly improves the submarine cable's resistance to environmental interference while reducing construction costs and environmental impact. Summary of the Invention

[0006] The purpose of this invention is to provide a design method for secondary stability intervention of submarine cables using a briquette structure. By scientifically calculating the stress and instability modes of the submarine cable and the submarine briquette structure, and optimizing the parameters and layout of the briquette structure, the long-term stability of the submarine cable in complex marine environments can be ensured.

[0007] The technical solution of the present invention:

[0008] A design method for secondary stabilization intervention of submarine cables using a block-type structure includes the following steps:

[0009] (1) Calculation of seabed flow conditions

[0010] Collect marine environmental data for the target sea area, including current velocity, wave height, and tidal cycle; use numerical simulation tools or empirical formulas to calculate seabed flow conditions, specifically including unidirectional flow velocity and wave-water particle velocity.

[0011] (2) Hydrodynamic and in-situ stability assessment of submarine cables

[0012] The stress on exposed submarine cables includes the horizontal hydrodynamic component F. x-c Vertical hydrodynamic component F y-c Frictional force F between the cable and the seabed f-c And the buoyancy W of the cable s-c The hydrodynamic forces acting on the submarine cable are calculated using the following formula:

[0013]

[0014] Among them, C x-c C y-c These are the horizontal and vertical hydrodynamic coefficients for the submarine cable, with values ​​referenced from DNV-RP-F109. w-c u represents the current velocity amplitude at the center elevation of the submarine cable caused by waves. c-c ρ is the current velocity at the center elevation of the submarine cable caused by unidirectional current. w The density of seawater;

[0015] The safety factor for the horizontal stability of a submarine cable is defined as:

[0016]

[0017] Where, μ c The coefficient of friction between the submarine cable and the seabed;

[0018] Assuming the minimum permissible safety factor for cable is SF. c-min Therefore, the average additional horizontal resistance required per meter to ensure the stability of the submarine cable is:

[0019] F r-c =SF c-min F x-c -μ c (W s-c -F y-c (4)

[0020] (3) Evaluation of the hydrodynamics and stability of the briquetted structure itself

[0021] Based on the shape and size of the briquette structure, its corresponding hydrodynamic coefficient is obtained through numerical simulation or physical experiment methods, and its stability and anti-slip capability under hydrodynamic action are calculated.

[0022] Under unidirectional flow, the compactor is subjected to a horizontal drag force F. d-b and vertical lift F l-b ; Cross-sectional area A of the rammed block's frontal surface c The maximum area A of the downward projection of the pressure block s Then the horizontal drag force F on the block is d-b and vertical lift F l-b for:

[0023]

[0024] Among them, u c-b C represents the flow velocity at the top of the compact. d-b and C y-b The drag force coefficient and lift coefficient of the briquette;

[0025] Under the combined action of waves and unidirectional flow, the ballast is subjected to a horizontal drag force F. d-b and inertial force F i-b Vertical lift F y-b The calculation formula is as follows:

[0026]

[0027] Among them, u w-b C represents the velocity amplitude caused by the wave at the top of the compactor. i-b V is the inertial force coefficient. r This refers to the volume of the compressed block;

[0028] The ballast maintains stability through friction between itself and the seabed; the frictional force F between the ballast and the seabed is... f-b for:

[0029] F f-b =μ b (W s-b -F l-b (10)

[0030] Where, μ b W is the coefficient of friction between the ballast and the seabed. s-b The buoyancy of the briquettes;

[0031] The safety factor SF of the briquette's own stability b Defined as:

[0032]

[0033] Assume the minimum allowable safety factor for briquettes is defined as SF. b-min Then, the additional lateral resistance provided by a single ballast block to the submarine cable is:

[0034] F r-b =μ b (W s-b -F l-b )-SF b-min (F d-b +F i-b (12)

[0035] (4) Block layout design

[0036] Based on cable length and stability requirements, determine the spacing and quantity of the clamping blocks. The layout design is shown in the attached figure. Figure 4 As shown. Assume the total length of the submarine cable is L. c Then the spacing between the pressure blocks ΔL b And the total number of blocks N b They are respectively:

[0037] ΔL b = F r-b / F r-c (13)

[0038] N b = L c / ΔL (14)

[0039] (5) Optimization of briquette structure and layout

[0040] Optimize the size and weight of the ballast blocks to reduce material costs and construction difficulty while meeting stability requirements. 1) The ballast block structures are made of concrete or composite materials, possessing good corrosion resistance and durability. 2) The shape of the ballast block structures is designed to be streamlined to reduce the impact of hydrodynamic loads on the stability of the ballast blocks themselves. 3) The spacing of the ballast block structures is dynamically adjusted according to the cable length and seabed flow conditions to ensure uniform distribution of stability.

[0041] The beneficial effects of this invention are:

[0042] 1) Through scientific calculations and optimized design, the stability of submarine cables in complex marine environments has been significantly improved.

[0043] 2) The design and layout of the briquette structure are flexible and can adapt to the environmental conditions of different sea areas.

[0044] 3) It reduces the risk of displacement, wear and breakage of submarine cables due to environmental factors, and extends the service life of the cables.

[0045] 4) It is easy to construct, has controllable costs, and has high engineering application value. Attached Figure Description

[0046] Figure 1 This is a flowchart of the design method of the present invention.

[0047] Figure 2 This is a schematic diagram of the stress on a submarine cable.

[0048] Figure 3 This is a schematic diagram of the forces acting on a block-type structure.

[0049] Figure 4 This is a schematic diagram of the arrangement of a block-type structure. Detailed Implementation

[0050] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0051] 1) Submarine Flow Condition Calculation: Data on current velocity, wave height, and tidal cycle in the target sea area are collected using marine environmental monitoring equipment. Characteristic velocities under extreme environmental conditions are calculated using empirical formulas. 2) Submarine Cable Hydrodynamic and In-situ Stability Assessment: Based on cable diameter, weight, and flow parameters, the hydrodynamic and lateral resistance of the submarine cable under design conditions are calculated. In-situ stability is assessed, and the required additional lateral resistance is determined. 3) Ballast Structure Hydrodynamic and Stability Assessment: Hydrodynamic coefficients of specific ballast structures under typical flow conditions are obtained using numerical simulation or physical experiments. The stability of the ballasts themselves is assessed, and the additional lateral resistance they can provide to the submarine cable is calculated. 4) Ballast Layout Design: The spacing and total number of ballasts are calculated based on the cable's stability requirements. 5) Ballast Structure and Layout Optimization: The aforementioned ballast layout scheme is evaluated based on the construction volume. Optimization of the ballast structure and dimensions can alter its hydrodynamic characteristics, improve its lateral anti-slip performance, and allow for a redesign of the layout, thereby further reducing the workload.

Claims

1. A design method for secondary stabilization intervention of submarine cables using a block-type structure, characterized in that, Includes the following steps: (1) Calculation of seabed flow conditions Collect marine environmental data for the target sea area, including current velocity, wave height, and tidal cycle; use numerical simulation tools or empirical formulas to calculate seabed flow conditions, specifically including unidirectional flow velocity and wave-water particle velocity. (2) Hydrodynamic and in-situ stability assessment of submarine cables The stress on exposed submarine cables includes the horizontal hydrodynamic component F. x-c Vertical hydrodynamic component F y-c Frictional force F between the cable and the seabed f-c And the buoyancy W of the cable s-c The hydrodynamic forces acting on the submarine cable are calculated using the following formula: Among them, C x-c C y-c These are the horizontal and vertical hydrodynamic coefficients for the submarine cable, with values ​​referenced from DNV-RP-F109. w-c u represents the current velocity amplitude at the center elevation of the submarine cable caused by waves. c-c ρ is the current velocity at the center elevation of the submarine cable caused by unidirectional current. w The density of seawater; The safety factor for the horizontal stability of a submarine cable is defined as: Where, μ c The coefficient of friction between the submarine cable and the seabed; Assuming the minimum permissible safety factor for cable is SF. c-min Therefore, the average additional horizontal resistance required per meter to ensure the stability of the submarine cable is: F r-c =SF c-min F x-c -μ c (W s-c -F y-c )(4) (3) Evaluation of the hydrodynamics and stability of the briquetted structure itself Based on the shape and size of the briquette structure, its corresponding hydrodynamic coefficient is obtained through numerical simulation or physical experiment methods, and its stability and anti-slip capability under hydrodynamic action are calculated. Under unidirectional flow, the compactor is subjected to a horizontal drag force F. d-b and vertical lift F l-b ; Cross-sectional area A of the rammed block's frontal surface c The maximum area A of the downward projection of the pressure block s Then the horizontal drag force F on the block is d-b and vertical lift F l-b for: Among them, u c-b C represents the flow velocity at the top of the compact. d-b and C y-b The drag force coefficient and lift coefficient of the briquette; Under the combined action of waves and unidirectional flow, the ballast is subjected to a horizontal drag force F. d-b and inertial force F i-b Vertical lift F y-b The calculation formula is as follows: Among them, u w-b C represents the velocity amplitude caused by the wave at the top of the compactor. i-b V is the inertial force coefficient. r This refers to the volume of the compressed block; The ballast maintains stability through friction between itself and the seabed; the frictional force F between the ballast and the seabed is... f-b for: F f-b =μ b (W s-b -F l-b )(10) Where, μ b W is the coefficient of friction between the ballast and the seabed. s-b The buoyancy of the briquettes; The safety factor SF of the briquette's own stability b Defined as: Assume the minimum allowable safety factor for briquettes is defined as SF. b-min Then, the additional lateral resistance provided by a single ballast block to the submarine cable is: F r-b =μ b (W s-b -F l-b )-SF b-min (F d-b +F i-b )(12) (4) Block layout design Based on the cable length and stability requirements, the spacing and number of clamping blocks are determined. Assume the total length of the submarine cable is L. c Then the spacing between the pressure blocks ΔL b And the total number of blocks N b They are respectively: ΔL b =F r-b / F r-c (13) N b =L c / ΔL(14) (5) Optimization of briquette structure and layout Optimize the size and weight of the compaction blocks to reduce material costs and construction difficulty while meeting stability requirements.

2. The design method for secondary stabilization intervention of submarine cables using a block-type structure according to claim 1, characterized in that, The blocks are made of concrete or composite materials.

3. The design method for secondary stabilization intervention of submarine cables using a block-type structure according to claim 1, characterized in that, The shape of the briquette is designed to be streamlined.

4. The design method for secondary stabilization intervention of submarine cables using a block-type structure according to claim 1, characterized in that, The spacing of the pressure blocks is dynamically adjusted according to the cable length and seabed flow conditions to ensure a stable and uniform distribution.

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