Method and system for predicting stress of submarine cables under high-pressure water gun impact

Abstract

The invention discloses a method and system for predicting the stress of a submarine cable under the impact of a high-pressure water gun, and relates to the field of submarine cable operation and maintenance. Currently, the impact stress of the cable during high-pressure water gun construction cannot be quantitatively evaluated. The invention comprises the following steps: using finite element simulation software to establish a three-dimensional fluid-solid coupling finite element model of the submarine cable under the impact of different high-pressure water gun flow rates, and using the model to solve and extract stress data of the submarine cable; using a nonlinear fitting method to process the simulation results, and establishing a one-variable nonlinear fitting formula for the impact of different high-pressure water gun flow rates and the stress of the submarine cable; obtaining a submarine cable stress prediction result based on the fitting formula and the current high-pressure water gun flow rate; the technical solution can quickly predict the impact of the high-pressure water gun on the submarine cable, so as to guide the safe flow rate control during construction and prevent cable damage.

Description

Technical Field

[0001] The present invention relates to the field of submarine cable operation and maintenance, and in particular to a method and system for predicting submarine cable stress under the impact of a high-pressure water gun. Background Art

[0002] With the deepening advancement of my country's marine economic strategy and the large-scale development of offshore clean energy, submarine cables have become core infrastructure for cross-sea power transmission and communications, carrying out energy and information transmission between islands and the mainland, and between offshore platforms and onshore power grids. Failure of submarine cables due to external forces is not only costly to repair, but also leads to significant socioeconomic losses, such as regional power outages and communication disruptions.

[0003] Buried pipelines, such as submarine natural gas pipelines, are often exposed or suspended due to ocean currents and geological activity, requiring regular trenching and reburial maintenance. To reduce construction risks, the industry generally uses non-contact trenching machines, which use high-pressure water jets to erode the seabed and form trenches.

[0004] There is spatial overlap between the high-pressure water gun operation area and the submarine cable laying area. The high-speed water flow produces dynamic fluid impact loads on the adjacent cable body, which may cause structural damage such as cable insulation rupture, armor deformation, and even conductor breakage.

[0005] Since there is no mature method to establish a quantitative relationship between the flow rate of a high-pressure water gun and cable stress, operation and maintenance personnel are unable to predict the cable's stress safety threshold at a specific flow rate. In addition, the seabed environment is complex, in-situ testing is extremely costly and difficult to extract accurate stress data.

[0006] Therefore, there is an urgent need to develop a high-precision, low-cost submarine cable stress-velocity relationship modeling method to provide a theoretical basis for setting the safe distance and flow rate control during high-pressure water gun construction, and to prevent cable impact damage accidents. Summary of the Invention

[0007] The technical problem to be solved and the technical task to be addressed by this invention are to improve and enhance existing technical solutions by providing a method and system for predicting submarine cable stress under high-pressure water jet impact. This method aims to accurately and cost-effectively analyze the stress changes in submarine cables under high-pressure water jet impact. To this end, this invention adopts the following technical solutions.

[0008] The stress prediction method of submarine cables under high-pressure water gun impact based on the fluid-structure coupling model includes the following steps:

[0009] 1) Establish a three-dimensional fluid-structure interaction finite element model of the submarine cable under different high-pressure water gun flow rates, including:

[0010] 1.1) Based on the layered structure of the submarine cable and the diameter d of the high-pressure water gun nozzle, a cable geometric model is constructed, where the cable length is not less than 3d, and the material parameters of each structural layer are set;

[0011] 1.2) Establish an external flow basin model that is consistent with the length of the cable and set a high-pressure water gun impact outlet directly above it;

[0012] 1.3) Using a non-uniform meshing method, the outer basin is meshed with a hexahedron, with the mesh density gradually increasing from the outer basin edge to the cable area. The cable layers are meshed using a sweeping mode.

[0013] 1.4) Apply fully constrained boundary conditions to both ends of the cable and set the structural layers to be in bonded contact;

[0014] 1.5) Set the high-pressure water gun flow rate range from 0 to the maximum flow rate N, take samples at intervals, and control the flow rate change using a step function;

[0015] 1.6) Calculate the stress distribution of the cable under different flow rates and extract the maximum stress data samples of each layer;

[0016] 2) Establish the fitting formula of stress and flow rate through nonlinear fitting method, including:

[0017] 2.1) Using velocity as the independent variable and stress as the dependent variable, a polynomial, exponential, or power function model is used to perform a univariate nonlinear fit on the sample data.

[0018] 2.2) Pass The best fitting method was selected for the coefficient of determination, and the accuracy of the fitting formula was verified using an independent data set;

[0019] 3) Based on the verified fitting formula and the current high-pressure water gun flow rate, the submarine cable stress prediction results are obtained.

[0020] This technical solution uses a three-dimensional fluid-structure interaction finite element model to simulate the dynamic interaction between high-pressure water flow and the cable's multilayer structure, overcoming the drawback of traditional static models that ignore the dynamic loads of fluid impact. Material parameters are set based on the cable's actual layered structure to ensure realistic mechanical responses. Cable ends are fully constrained to simulate actual installation conditions; interlayer bonded contact prevents unphysical relative sliding. A step function controls flow velocity for efficient simulation of impact transients. A hexahedral mesh with local refinement is used in the outer flow domain to balance computational accuracy and speed; a swept mesh is used within the cable's layered structure to improve efficiency in meshing complex geometries. Simultaneous trials of polynomial, exponential, and power function models address the limitations of a single model. Validation with independent datasets prevents overfitting and enhances engineering generalization. Sample generation based on fluid-structure interaction simulation data preserves physical laws while extracting a concise quantitative stress-velocity equation through fitting, facilitating rapid on-site table lookup and prediction. This technical solution can replace costly and risky in-situ subsea testing, requiring only flow velocity input to generate stress values. Flexible parameter adjustments (e.g., changing cable material or water nozzle diameter) allow for adaptability to diverse engineering scenarios. The prediction results can quantitatively assess the safe flow rate threshold for high-pressure water gun operation, preventing cable damage (such as insulation cracking and armor deformation). This also provides a theoretical basis for trenching route planning, reducing operational risks. Through high-fidelity simulation, intelligent sampling strategies, and rigorous mathematical verification, this technical solution addresses the three major pain points in submarine cable stress prediction: insufficient accuracy, experimental difficulties, and a lack of quantitative tools. This approach combines academic innovation with practical engineering value, providing key technical support for the safe operation and maintenance of submarine energy infrastructure.

[0021] As a preferred technical means: in step 1.1), the layered structure of the submarine cable includes a conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer, an armor layer and an outer sheath. When constructing the cable geometric model, the conductor is simplified into a cylinder, the conductor shielding layer, the insulating layer and the insulating shielding layer are combined into one layer, and the armor layer is simplified into a torus. The density, elastic modulus and Poisson's ratio of each layer are consistent with the actual parameters.

[0022] Merging the conductor shield, insulation layer, and insulation shield into a single layer reduces mesh size and shortens simulation time. The conductor → cylinder and armor → torus model preserves core mechanical features, avoids mesh distortion caused by unnecessary details (such as the helical structure of the conductor strands and gaps between armor wires), improves swept meshing speed, and enhances convergence stability. Density, elastic modulus, and Poisson's ratio match measured values, maintaining material parameter fidelity and reducing stress prediction errors. Layered mechanical responses are independent, preserving the constitutive differences between the conductor (metal), merged layer (polymer), and armor (composite) to accurately capture interlayer stress transfer paths. This provides a cost-effective input foundation for fluid-structure interaction simulations.

[0023] As a preferred technical approach: in step 1.2), the outer flow domain is surrounded by an open surface.

[0024] The open surface of the outer flow basin conforms to the law of free fluid diffusion and can accurately simulate the fluid dynamics behavior in a real marine environment, resolving key shortcomings of traditional closed flow basin models. These models suffer from problems such as false pressure accumulation caused by pressure wave reflection at the boundary, the need to manually set the outlet pressure, which subjectively interferes with the flow field, and the neglect of the dissipation of fluid kinetic energy to the far field. This technical solution, however, utilizes an open surface model with the following advantages: pressure waves can escape freely, conforming to the characteristics of infinite water, which helps reduce the error in the peak impact pressure; it automatically satisfies the law of mass conservation to achieve dynamic equilibrium inlet / outlet flow, and the velocity distribution is more consistent with the actual jet diffusion law; it simulates the energy decay process after water impact, thereby accurately capturing the time decay characteristics of the cable force. It also improves computational efficiency. The open boundary allows fluid to flow freely in and out, avoiding the iterative solution of the Poisson equation for pressure, which helps reduce the number of computational iterations; it eliminates numerical oscillations caused by pressure reflection in closed models, which helps increase the time step, thereby shortening the total computation time; it uses the simplest boundary conditions to solve common problems in complex fluid impact simulations, setting a new benchmark for fluid-structure interaction accuracy.

[0025] As a preferred technical measure: in step 1.5), the interval between adjacent sample points shall not exceed 0.2N.

[0026] Avoid losing key data in nonlinear areas.

[0027] As a preferred technical means: the number M of samples of the high-pressure water gun flow rate is an integer not less than 5, and the flow rate range is divided into a low-pressure area and a high-pressure area, wherein the interval between sample points in the high-pressure area is smaller than that in the low-pressure area.

[0028] Cable stress changes are usually more dramatic in the high-pressure area (close to the maximum flow velocity N). Reducing the sample point interval (for example, 0.2N interval in the low-pressure area and 0.1N interval in the high-pressure area) can increase the data density in the high-flow velocity section and more accurately capture nonlinear characteristics, meeting the engineering optimization requirements of fluid-structure interaction simulation.

[0029] As a preferred technical means: In step 2.2), calculate the Coefficient of determination and mean square error, select The model with a mean square error greater than 0.9 and the smallest mean square error is taken as the optimal fitting formula; the sample data is equally divided into a training set and a validation set, and the validation set is used to test the error of the fitting formula. If the error is within the allowable range, the fitting formula is used for subsequent submarine cable stress prediction; otherwise, the optimal fitting formula is re-screened.

[0030] Another technical solution of the present invention is a submarine cable stress prediction system, which includes:

[0031] 1. 3D fluid-solid coupling finite element modeling module, used to establish a simulation model of submarine cables under different high-pressure water gun flow rates; the 3D fluid-solid coupling finite element modeling module includes:

[0032] The geometric modeling unit is used to build a cable geometric model based on the layered structure of the submarine cable and the diameter d of the high-pressure water gun nozzle. The cable length is not less than 3d, and the material parameters of each structural layer are set;

[0033] The outer flow basin modeling unit establishes an outer flow basin model that is consistent with the length of the cable, and sets a high-pressure water gun impact outlet directly above it;

[0034] The meshing unit adopts the non-uniform meshing method, performs hexahedral meshing on the outer basin, gradually densifies from the edge of the outer basin to the cable, and performs sweep mode meshing on each layer of the cable;

[0035] The boundary condition setting unit applies fully constrained boundary conditions to both ends of the cable, and sets the bonded contact between each structural layer;

[0036] A flow rate control unit sets the flow rate of the high-pressure water gun to a range from 0 to a maximum flow rate N, samples at intervals not exceeding 0.2N, and controls the flow rate change through a step function;

[0037] The solution and data extraction unit solves the stress distribution of the cable under different flow rates and extracts the maximum stress data samples of each layer;

[0038] 2. Nonlinear fitting modeling module, used to establish the quantitative relationship formula between stress and flow velocity, specifically including:

[0039] The fitting model unit uses velocity as the independent variable and stress as the dependent variable to fit the sample data with polynomial, exponential and power function models;

[0040] Model screening unit, through The best fitting method was selected for the coefficient of determination, and the accuracy of the fitting formula was verified using an independent data set;

[0041] 3. Stress prediction module, which is used to output the corresponding submarine cable stress prediction results based on the verified fitting formula and the input high-pressure water gun flow rate value.

[0042] This technical solution ensures prediction errors through material fidelity, dynamic verification, and anti-interference algorithms. It transforms the complex fluid-structure coupling theory into a "flow velocity input → stress output" system, providing efficient and reliable tool support for submarine cable operation and maintenance.

[0043] As a preferred technical means: in the geometric modeling unit, the layered structure of the submarine cable includes a conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer, an armor layer and an outer sheath. When constructing the cable geometric model, the conductor is simplified into a cylinder, the conductor shielding layer, the insulating layer and the insulating shielding layer are merged into one layer, and the armor layer is simplified into a torus. The density, elastic modulus and Poisson's ratio of each layer are consistent with the actual parameters.

[0044] As an optimal technical means: in the flow rate control unit, the number M of samples of the high-pressure water gun flow rate is an integer not less than 5, and the flow rate range is divided into a low-pressure area and a high-pressure area, wherein the sample point interval in the high-pressure area is smaller than that in the low-pressure area.

[0045] As a preferred technical means: the model screening unit calculates the Coefficient of determination and mean square error, select The model with a mean square error greater than 0.9 and the smallest mean square error is taken as the optimal fitting formula; the sample data is equally divided into a training set and a validation set, and the validation set is used to test the error of the fitting formula. If the error is within the allowable range, the fitting formula is used for subsequent submarine cable stress prediction; otherwise, the optimal fitting formula is re-screened.

[0046] Beneficial effects:

[0047] 1. The present invention makes full use of the characteristics of various simulation analysis methods and can accurately obtain the deformation of each layer of the submarine cable under different high-pressure water gun flow rates.

[0048] 2. The present invention overcomes the shortcomings of physical experiments such as difficulty, high cost, low efficiency, and difficulty in data extraction.

[0049] 3. The present invention proposes a nonlinear fitting method to obtain the relationship between the stress of the submarine cable body and the flow rate of the high-pressure water gun, which is convenient for calculation, accurate in data, and convenient for engineering practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The figure is a flow chart for establishing the relationship between the stress of the submarine cable body and the flow rate of the high-pressure water gun of the present invention.

[0051] Figure 2 The internal structure of a submarine cable.

[0052] Figure 3 for Figure 2 Magnified view of part A.

[0053] Figure 4 Schematic diagram of submarine cable structure.

[0054] Figure 5 This is the grid division effect of the watershed outside the submarine cable.

[0055] Figure 6 Meshing diagram for the submarine cable model.

[0056] Figure 7 This is the stress diagram of the submarine cable.

[0057] Figure 8 This is a fitting diagram of the relationship between submarine cable stress and high-pressure water gun flow rate. DETAILED DESCRIPTION

[0058] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings.

[0059] Example 1:

[0060] The method for predicting submarine cable stress under high-pressure water gun impact based on the fluid-structure coupling model includes establishing the relationship between the submarine cable body stress and the high-pressure water gun flow rate and predicting the submarine cable stress under high-pressure water gun impact based on the established relationship between the submarine cable body stress and the high-pressure water gun flow rate. The specific process of establishing the relationship between the submarine cable body stress and the high-pressure water gun flow rate is as follows: Figure 1 As shown, the following steps are included:

[0061] S1: Establish a three-dimensional fluid-structure interaction finite element model of the submarine cable under different high-pressure water gun flow rates, including:

[0062] S1.1: Based on the layered structure of the submarine cable and the diameter d of the high-pressure water gun nozzle, construct a cable geometric model, where the cable length is not less than 3d, and set the material parameters of each structural layer;

[0063] S1.2: Establish an external flow basin model that is consistent with the length of the cable and set a high-pressure water gun impact outlet directly above it;

[0064] S1.3: Use a non-uniform meshing method to create a hexahedral mesh for the outer basin, gradually increasing the mesh density from the outer basin edge toward the cable area; use a sweeping mode to mesh each layer of the cable.

[0065] S1.4: Apply fully constrained boundary conditions to both ends of the cable and set the structural layers to be in bonded contact;

[0066] S1.5: Set the high-pressure water gun flow rate range from 0 to the maximum flow rate N, sample at intervals, and control the flow rate change using a step function;

[0067] S1.6: Determine the stress distribution of the cable under different flow rates and extract the maximum stress data samples of each layer;

[0068] S2: Establish the fitting formula of stress and flow rate through nonlinear fitting method, including:

[0069] S2.1: Using velocity as the independent variable and stress as the dependent variable, perform a univariate nonlinear fit on the sample data using a polynomial, exponential, or power function model;

[0070] S2.2: Pass The best fitting method was selected for the coefficient of determination, and the accuracy of the fitting formula was verified using an independent data set.

[0071] When it is necessary to predict the stress of the submarine cable under the impact of a high-pressure water gun, the submarine cable stress prediction result is obtained based on the verified fitting formula and the current high-pressure water gun flow rate.

[0072] The following takes the 500kV oil-filled submarine cable as the research object and explains the technical solution in detail.

[0073] 1. Take 500kV oil-filled submarine cable as the research object, its internal structure is as follows Figure 2 、 Figure 3 As shown, from inside to outside are oil channel, copper conductor, conductor shielding layer, insulation layer, insulation shielding layer, copper braided tape, lead alloy sheath, reinforcement layer, first lining layer, anti-corrosion layer, anti-termite layer, second lining layer, armor, and outer sheath.

[0074] The cable dimensions and material parameters of each layer are shown in Tables 1 and 2. The conductor shield, insulation layer, and insulation shield have similar mechanical properties, and since the conductor shield and insulation shield are very thin, the insulation layer is combined. The first copper braid, reinforcement layer, and second copper braid are very thin, so they are combined into the lead alloy sheath. The first lining, anticorrosion layer, mothproof layer, and second lining have similar material parameters, and since the first lining, mothproof layer, and second lining are very thin, the anticorrosion layer is combined.

[0075] Table 1 Cable size parameters

[0076]

[0077] Table 2 Submarine cable material parameters

[0078]

[0079] 2. Establish a three-dimensional fluid-solid coupling finite element model of the submarine cable under different high-pressure water gun flow rates, and use this model to simulate the stress distribution of the submarine cable under different high-pressure water gun flow rates.

[0080] Using finite element simulation software to establish a finite element model of a submarine cable requires the following steps: selecting units and material models, establishing a geometric model, meshing, and applying loads. The specific steps are as follows:

[0081] (1) Model setting

[0082] Finite element analysis can flexibly set the structure and material parameters of submarine cables, as well as various boundary conditions, and can fully simulate the working conditions of submarine cables. Figure 4This is a schematic diagram of the entire submarine cable and the high-pressure water gun impact. The high-pressure water gun diameter is set to 60cm, and the submarine cable model length is selected to be no less than three times the high-pressure water gun diameter. The final submarine cable length is selected to be 2.3m. Based on the current practical situation of high-pressure water gun impact on submarine cables, the high-pressure water gun impact position is selected to be located in the center of the submarine cable. Based on the actual high-pressure water gun impact flow rate, the flow rate is set to vary between 0 and 10m / s. Based on the marine environment in which the submarine cable is located, the left and right boundary distances are set to 1m.

[0083] (2) Finite element setting

[0084] The fluid module and transient structure module in the finite element simulation software are selected to analyze the stress of each layer of materials when the submarine cable is impacted by a high-pressure water gun. The fluid module is used to analyze the water flow process of the high-pressure water gun impact, and the transient structure module is used to calculate the structural changes and stress analysis of the submarine cable under impact.

[0085] After determining the unit type and material parameters, the transient finite element model of the submarine cable can be established according to the structure and geometric model size of the submarine cable for meshing. The denser the meshing, the more accurate the calculation results, but the amount of calculation will increase geometrically. Since the submarine cable body and the surrounding waters undergo drastic changes during the impact of the high-pressure water gun, the meshing of these areas is denser. The manual meshing method is used to set the mesh size to 150mm in the outer basin, and the mesh becomes gradually denser near the submarine cable. The hexahedral mesh is used, and the submarine cable model adopts the sweeping method and the surface meshing method to mesh the submarine cable, such as Figure 5 、 Figure 6 As shown in the figure, the grid has regular shape, moderate density and uniform distribution, which meets the calculation accuracy requirements.

[0086] Analysis of actual submarine cable installations reveals that cables typically range in length from several kilometers to tens of kilometers. When a section of the cable is subjected to a high-pressure water jet, the cable ends can be effectively immobilized. Applying a load to both ends of the cable acts as a fixed constraint, securing the cable.

[0087] (3) Finite element model calculation and result analysis

[0088] In order to accurately obtain the relationship between the submarine cable stress and the high-pressure water gun flow rate, sufficient data samples are required. The high-pressure water gun flow rate is set to 3m / s, 5m / s, 7m / s, 9m / s and 10m / s, the calculation time is set to 0.2s, and the time step is 0.002s. Finite element models are established and solved respectively, and finally the submarine cable stress is extracted from the results.

[0089] The stress results of submarine cables obtained by finite element analysis are as follows: Figure 6As shown in the figure, the position where the submarine cable is impacted by the high-pressure water gun produces the largest deformation, and the deformation at other positions decreases from the inside to the outside, which is consistent with the actual situation.

[0090] The stress results of each layer of the submarine cable are extracted from the solution results of the fluid-solid coupling finite element model, and a three-dimensional stress cloud diagram is drawn, such as Figure 7 As shown in the figure, when the high-pressure water jet velocity is 5 m / s, the maximum deformation of the submarine cable is 0.524 mm. The deformation of the submarine cable increases with the increase of the high-pressure water jet velocity, and shows a nonlinear trend.

[0091] 3. Nonlinear fitting method

[0092] Through the analysis of experimental data, the above data are univariate nonlinear data, and it is necessary to build a univariate nonlinear fitting model. The following steps are taken for analysis:

[0093] The first step is to establish a one-dimensional nonlinear fitting formula for the impact velocity of the high-pressure water gun and the stress of the submarine cable. Polynomial fitting, exponential fitting and power function fitting are used to fit the data. The fitting degree of different methods is compared. Coefficient of determination, The closer to 1, the better the fitting degree. The fitting method with the highest fitting degree greater than 0.9 is used as the fitting method between the stress of the submarine cable body and the flow rate of the high-pressure water gun, and the most appropriate model parameters are selected; let the impact flow rate of the high-pressure water gun be m, and the stress on the submarine cable be n. From the analysis in Table 3, it can be seen that the equation obtained by the power series fitting method has a good relationship with m and n. The fitting coefficient is the best and the SSE is smaller. The optimal equation is shown in formula (1). Similarly, the equations of polynomial fitting and exponential fitting methods are shown in formulas (2) and (3).

[0094] (1)

[0095] (2)

[0096] (3)

[0097] Table 3 Statistical data of each model in the regression calculation process of high-pressure water gun flow rate and submarine cable stress

[0098]

[0099] Step 2: Verify and judge reliability and desirability.

[0100] Two sets of new data are used to verify the fitting characteristics and accuracy of the constructed univariate nonlinear fitting formula. Figure 8The figure shows the relationship between submarine cable stress and high-pressure water gun flow rate. Observing the graph, the proposed formula shows that the calculation error is within the allowable range, the calculation speed is fast, and it has strong engineering practical value. However, there is room for improvement in the amount of fitting data and accuracy.

[0101] Example 2:

[0102] The submarine cable stress prediction system includes:

[0103] 1. 3D fluid-solid coupling finite element modeling module, used to establish a simulation model of submarine cables under different high-pressure water gun flow rates; the 3D fluid-solid coupling finite element modeling module includes:

[0104] The geometric modeling unit is used to construct a cable geometric model based on the layered structure of the submarine cable and the diameter d of the high-pressure water gun nozzle. The cable length is not less than 3d, and the material parameters of each structural layer are set; the conductor is simplified into a cylinder, the conductor shielding layer, the insulation layer, and the insulation shielding layer are merged into one layer, and the armor layer is simplified into a torus. The density, elastic modulus, and Poisson's ratio of each layer are consistent with the actual parameters.

[0105] The outer flow basin modeling unit establishes an outer flow basin model that is consistent with the length of the cable, and sets a high-pressure water gun impact outlet directly above it.

[0106] The grid division unit adopts the non-uniform grid division method, performs hexahedral grid division on the outer basin, gradually densifies from the edge of the outer basin to the cable, and performs sweep mode grid division on each layer of the cable.

[0107] The boundary condition setting unit applies fully constrained boundary conditions to both ends of the cable, and the structural layers are set to be in bonded contact.

[0108] The flow rate control unit sets the flow rate of the high-pressure water gun to a range from 0 to the maximum flow rate N, samples at intervals not exceeding 0.2N, and controls the flow rate change through a step function; the number of samples M of the high-pressure water gun flow rate is an integer not less than 5, and the flow rate range is divided into a low-pressure area and a high-pressure area, wherein the sample point interval in the high-pressure area is smaller than that in the low-pressure area.

[0109] The solution and data extraction unit solves the stress distribution of the cable under different flow rates and extracts the maximum stress data samples of each layer.

[0110] 2. Nonlinear fitting modeling module, used to establish the quantitative relationship formula between stress and flow velocity, specifically including:

[0111] The fitting model unit uses flow velocity as the independent variable and stress as the dependent variable to fit the sample data with polynomial, exponential and power function models.

[0112] Model screening unit, through The optimal fitting method was selected based on the determination coefficient, and the accuracy of the fitting formula was verified using an independent data set; the accuracy of each fitting model was calculated. Coefficient of determination and mean square error, select The model with a mean square error greater than 0.9 and the smallest mean square error is taken as the optimal fitting formula; the sample data is equally divided into a training set and a validation set, and the validation set is used to test the error of the fitting formula. If the error is within the allowable range, the fitting formula is used for subsequent submarine cable stress prediction; otherwise, the optimal fitting formula is re-screened.

[0113] 3. Stress prediction module, which is used to output the corresponding submarine cable stress prediction results based on the verified fitting formula and the input high-pressure water gun flow rate value.

[0114] This system, through its precise modeling, intelligent fitting, and rapid prediction capabilities, provides a complete submarine cable stress prediction solution. It transforms complex physical processes into computable digital models, combining engineering practicality with technological advancements to provide efficient and reliable tool support for submarine cable operation and maintenance.

[0115] It is understandable that the detailed functional implementation of the above modules can be found in the introduction of the aforementioned method embodiment, and no further details are given here.

[0116] The above-mentioned method and system for predicting submarine cable stress under high-pressure water gun impact are specific embodiments of the present invention, which have embodied the substantial features and progress of the present invention. Based on actual use needs and under the guidance of the present invention, equivalent modifications can be made to them, which are all within the scope of protection of this solution.

Claims

1. The stress prediction method of submarine cables under high-pressure water gun impact based on fluid-structure coupling model is characterized by The following steps are involved: 1) Establish a three-dimensional fluid-structure interaction finite element model of the submarine cable under different high-pressure water gun flow rates, including: 1.1) Based on the layered structure of the submarine cable and the diameter d of the high-pressure water gun nozzle, a cable geometric model is constructed, where the cable length is not less than 3d, and the material parameters of each structural layer are set; 1.2) Establish an external flow basin model that is consistent with the length of the cable and set a high-pressure water gun impact outlet directly above it; 1.3) Using a non-uniform meshing method, the outer basin is meshed with a hexahedron, with the mesh density gradually increasing from the outer basin edge to the cable area. The cable layers are meshed using a sweeping mode. 1.4) Apply fully constrained boundary conditions to both ends of the cable and set the structural layers to be in bonded contact; 1.5) Set the high-pressure water gun flow rate range from 0 to the maximum flow rate N, take samples at intervals, and control the flow rate change using a step function; 1.6) Calculate the stress distribution of the cable under different flow rates and extract the maximum stress data samples of each layer; 2) Establish the fitting formula of stress and flow rate through nonlinear fitting method, including: 2.1) Using velocity as the independent variable and stress as the dependent variable, a polynomial, exponential, or power function model is used to perform a univariate nonlinear fit on the sample data. 2.2) Pass The best fitting method was selected for the coefficient of determination, and the accuracy of the fitting formula was verified using an independent data set; 3) Based on the verified fitting formula and the current high-pressure water gun flow rate, the submarine cable stress prediction results are obtained.

2. The method for predicting submarine cable stress under high-pressure water gun impact based on a fluid-structure coupling model according to claim 1 is characterized in that: In step 1.1), the layered structure of the submarine cable includes a conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer, an armor layer, and an outer sheath. When constructing the cable geometric model, the conductor is simplified into a cylinder, the conductor shielding layer, the insulating layer, and the insulating shielding layer are combined into one layer, and the armor layer is simplified into a torus. The density, elastic modulus, and Poisson's ratio of each layer are consistent with actual parameters.

3. The method for predicting submarine cable stress under high-pressure water gun impact based on a fluid-structure coupling model according to claim 1 is characterized in that: In step 1.2), the outer flow domain is set as an open surface on all sides.

4. The method for predicting submarine cable stress under high-pressure water gun impact based on a fluid-structure coupling model according to claim 1 is characterized in that: In step 1.5), the interval between adjacent sample points should not exceed 0.2N.

5. The method for predicting submarine cable stress under high-pressure water gun impact based on a fluid-structure coupling model according to claim 4 is characterized in that: The number M of samples of the high-pressure water gun flow rate is an integer not less than 5, and the flow rate range is divided into a low-pressure area and a high-pressure area, wherein the interval between sample points in the high-pressure area is smaller than that in the low-pressure area.

6. The method for predicting submarine cable stress under high-pressure water gun impact based on a fluid-structure coupling model according to claim 1 is characterized in that: In step 2.2), calculate the Coefficient of determination and mean square error, select The model with a mean square error greater than 0.9 and the smallest mean square error is selected as the optimal fitting formula. The sample data is divided equally into a training set and a validation set. The validation set is used to test the error of the fitting formula. If the error is within the allowable range, the fitting formula is used for subsequent submarine cable stress prediction. Otherwise, re-screen the optimal fitting formula.

7. A submarine cable stress prediction system using the method for predicting submarine cable stress under high-pressure water gun impact based on a fluid-structure coupling model according to claim 1, characterized in that include:

1. 3D fluid-structure interaction finite element modeling module, used to build simulation models of submarine cables under different high-pressure water gun flow rates; The 3D fluid-structure interaction finite element modeling module includes: The geometric modeling unit is used to build a cable geometric model based on the layered structure of the submarine cable and the diameter d of the high-pressure water gun nozzle. The cable length is not less than 3d, and the material parameters of each structural layer are set; The outer flow basin modeling unit establishes an outer flow basin model that is consistent with the length of the cable, and sets a high-pressure water gun impact outlet directly above it; The meshing unit adopts the non-uniform meshing method, performs hexahedral meshing on the outer basin, gradually densifies from the edge of the outer basin to the cable, and performs sweep mode meshing on each layer of the cable; The boundary condition setting unit applies fully constrained boundary conditions to both ends of the cable, and the structural layers are set to be in bonded contact; The flow rate control unit sets the flow rate of the high-pressure water gun to the range of 0 to the maximum flow rate N, takes samples at intervals, and controls the flow rate change through a step function; The solution and data extraction unit solves the stress distribution of the cable under different flow rates and extracts the maximum stress data samples of each layer; 2. Nonlinear fitting modeling module, used to establish the quantitative relationship formula between stress and flow velocity, specifically including: The fitting model unit uses velocity as the independent variable and stress as the dependent variable to fit the sample data with polynomial, exponential and power function models; Model screening unit, through The best fitting method was selected for the coefficient of determination, and the accuracy of the fitting formula was verified using an independent data set; 3. Stress prediction module, which is used to output the corresponding submarine cable stress prediction results based on the verified fitting formula and the input high-pressure water gun flow rate value.

8. The submarine cable stress prediction system according to claim 7, characterized in that: In the geometric modeling unit, the layered structure of the submarine cable includes a conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer, an armor layer, and an outer sheath. When constructing the cable geometric model, the conductor is simplified into a cylinder, the conductor shielding layer, the insulating layer, and the insulating shielding layer are combined into one layer, and the armor layer is simplified into a torus. The density, elastic modulus, and Poisson's ratio of each layer are consistent with the actual parameters.

9. The submarine cable stress prediction system according to claim 7, characterized in that: In the flow rate control unit, the number M of samples of the high-pressure water gun flow rate is an integer not less than 5, and the flow rate range is divided into a low-pressure area and a high-pressure area, wherein the sample point interval in the high-pressure area is smaller than that in the low-pressure area.

10. The submarine cable stress prediction system according to claim 7, characterized in that: The model screening unit calculates the Coefficient of determination and mean square error, select The model with a mean square error greater than 0.9 and the smallest mean square error is selected as the optimal fitting formula. The sample data is divided equally into a training set and a validation set. The validation set is used to test the error of the fitting formula. If the error is within the allowable range, the fitting formula is used for subsequent submarine cable stress prediction. Otherwise, re-screen the optimal fitting formula.

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