A method for judging the stability of submarine pipelines based on the analysis of submarine scouring mechanism

Abstract

The present invention discloses a method for judging the stability of submarine pipelines based on the analysis of submarine scouring mechanisms, which relates to the technical field of submarine facility protection. Basic data of the target sea area are obtained, including geological information of the area where the submarine pipeline is located, hydrological information of the sea area near the pipeline, and pipeline information. Feature analysis is carried out on the basic data of the target sea area, and feature data related to water flow scouring, wave scouring, and soil particle movement are extracted. Through the analysis of submarine scouring mechanisms, the present invention accurately identifies the risk areas around the pipeline that are vulnerable to scouring effects, and then focuses on monitoring and warning these risk areas, thereby strengthening protection measures in a targeted manner. Moreover, through continuous monitoring and analysis, the impact of scouring on the pipeline stability is dynamically evaluated, problems such as pipeline deformation and stress concentration caused by scouring can be detected in a timely manner, and the maintenance strategy can be adjusted accordingly. This not only improves the pertinence of safety protection, but also effectively saves resources and reduces maintenance costs.

Description

Technical Field

[0001] The present invention relates to the technical field of submarine facility protection, and particularly relates to a method for judging the stability of submarine pipelines based on the analysis of submarine scouring mechanisms. Background Art

[0002] Submarine scouring refers to the phenomenon that sediments are transported under the impact of waves and ocean currents at the contact between marine engineering structures and the seabed. The marine environment is complex and changeable, and submarine pipelines will be affected by various factors during the laying and operation processes, including waves, ocean currents, sediment conditions, etc. The scouring phenomenon may cause the loss of sediments around the submarine pipeline, making the pipeline lose support, and then leading to safety risks such as pipeline displacement, deformation, and even fracture. Therefore, accurately evaluating the impact of submarine scouring on pipeline stability is of great significance for ensuring the safe operation of pipelines.

[0003] The submarine scouring mechanism involves various interferences such as ocean currents, waves, and sediment particle movement. The interaction between these movements makes the scouring mechanism more complex. And a single evaluation of the impact of scouring movement on the stability of submarine pipelines will lead to a reduction in overall accuracy and even cause misguidance. Therefore, how to comprehensively consider the interferences of various movements of the submarine scouring mechanism to accurately judge the stability of submarine pipelines is the problem we need to solve. For this purpose, a method for judging the stability of submarine pipelines based on the analysis of submarine scouring mechanisms is proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for judging the stability of submarine pipelines based on the analysis of submarine scouring mechanisms to solve the problems raised in the above background art.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for judging the stability of submarine pipelines based on the analysis of submarine scouring mechanisms includes the following steps:

[0007] Step 1, obtaining the basic data of the target sea area, including the geological information of the area where the submarine pipeline is located, the hydrological information of the sea area near the pipeline, and the pipeline information;

[0008] Step 2, conducting a feature analysis on the basic data of the target sea area, extracting the feature data related to ocean current scouring, wave scouring, and sediment particle movement, and analyzing the migration and deposition trends of sediment particles under submarine scouring conditions;

[0009] Step 3, comprehensively considering the analysis results of ocean current scouring, wave scouring, and sediment particle movement to determine the scouring depth of the sediments around the submarine pipeline in the target sea area;

[0010] Step 4: Based on the pipeline information, obtain the stress threshold and deformation threshold of the subsea pipeline, and combine the analysis results of the scour depth to evaluate the abnormal state of the subsea pipeline under the action of scour, so as to judge the stability of the subsea pipeline.

[0011] Step 5: According to the evaluation results of the subsea pipeline stability, issue risk warning information and formulate targeted protection measures.

[0012] A further improvement of the technical solution of the present invention lies in that: in the said Step 1, the process of obtaining the basic data of the target sea area is as follows:

[0013] According to the specific position and orientation of the subsea pipeline, delimit the sea area range where data needs to be collected, and identify the key nodes such as pipeline turning points, intersection points, and deep-water areas, as well as potential risk areas in geological disaster-prone areas and waterway intersection areas, as the key positions for data collection.

[0014] Use geological exploration technology (gravity exploration) to obtain geological information such as seabed topography, stratigraphic structure, and bottom sediment type, consult historical geological data to obtain geological changes, seismic activities, and fault distribution information of the target sea area, and use the data of existing ocean observation stations to obtain hydrological information such as tides, ocean currents, waves, temperature, and salinity in the sea area near the pipeline.

[0015] Obtain the design drawings, construction records, and operation logs of the pipeline from the pipeline construction unit and operation unit, extract the basic information of the pipeline (material, diameter, wall thickness, burial depth, anti-corrosion measures, etc.), and use a subsea pipeline detection device based on the CT principle to conduct non-destructive detection on the pipeline to obtain the operation status information such as pipeline wall thickness, defect distribution, and corrosion degree.

[0016] Integrate the collected geological information, hydrological information, and pipeline information to form a basic data sequence list of the sea area. Among them, the basic data sequence list of the sea area includes the name, source, time, location, and numerical information of the data, and verify the integrated data to ensure the accuracy, integrity, and consistency of the data. Store the relevant data of the basic data sequence list of the sea area in the database.

[0017] A further improvement of the technical solution of the present invention lies in that: in the said Step 2, the analysis process of sediment particle migration and deposition trend is as follows:

[0018] Extract the basic data sequence list of the sea area from the database, and conduct feature analysis on the basic data of the target sea area in the basic data sequence list of the sea area, and respectively extract the features related to ocean current scour, wave scour, and sediment particle movement.

[0019] Based on the hydrological information data in the sea area basic data sequence table, determine the parameters of sea current velocity, direction, wave height, period, and direction to analyze the characteristics of sea current scouring and wave scouring. And based on the geological information data, determine the parameters of sediment particle size distribution, density, and permeability to analyze the characteristics of sediment particle movement;

[0020] Extract the parameters of sea current velocity and direction, determine the characteristic values of sea current scouring force and sea current power. Extract the parameters of wave height, period, and direction from the wave data, determine the characteristic values of wave dynamic pressure and shear force. Based on the determined parameters of sediment particle size distribution, density, and permeability, determine the characteristic values of sediment erosion rate and deposition rate;

[0021] Based on the characteristic values of sea current scouring force and sea current power, combined with the sediment characteristics, calculate the sea current scouring tendency index, analyze the scouring trend of the sea current on sediment particles, and clarify the migration direction and intensity of sediment particles under the action of sea current scouring;

[0022] Based on the characteristic values of wave dynamic pressure and shear force, combined with the sediment characteristics, calculate the wave scouring tendency index, analyze the scouring trend of waves on seabed sediments, and clarify the migration direction and intensity of sediment particles under the action of wave scouring;

[0023] Perform superposition analysis on the sea current scouring tendency index and the wave scouring tendency index, comprehensively consider the interaction between the sea current and the wave, calculate the sediment particle movement tendency index, and comprehensively analyze the migration and deposition trends of sediment particles under the combined action of the sea current and the wave.

[0024] A further improvement of the technical solution of the present invention is that the expression of the sea current scouring tendency index is:

[0025] ;

[0026] Wherein, is the sea current scouring tendency index, The value range of is between 0 and 1, is the actual sea current scouring force, calculated based on the sea current velocity, direction, and sediment characteristics, is the reference sea current scouring force, which is a preset reference value used to standardize the sea current scouring force, V is the actual sea current velocity, is the reference sea current velocity, corresponding to , is the median particle size of the sediment, is the reference sediment particle size, which is a preset reference value used to standardize the particle size, is the sediment particle density, is the water density. When is close to 1, it indicates that the sea current scouring force is strong and the sediment particles are easily scoured. When When it is close to 0, it indicates that the seabed current scouring force is weak and sediment particles are not easily scoured.

[0027] The expression of the wave scouring tendency index is as follows:

[0028] ;

[0029] Wherein, is the wave scouring tendency index, The value range of is between 0 and 1. is the actual wave dynamic pressure, which is calculated based on wave height, period and direction. is the reference wave dynamic pressure, which is a preset reference value used to standardize the wave dynamic pressure. is the actual wave shear force, which is calculated based on wave characteristics and sediment characteristics. is the reference wave shear force, which is a preset reference value used to standardize the shear force. When is close to 1, it indicates that the wave scouring force is strong and sediment particles are easily scoured. When is close to 0, it indicates that the wave scouring force is weak and sediment particles are not easily scoured.

[0030] The expression of the sediment particle movement tendency index is as follows:

[0031] ;

[0032] Wherein, is the sediment particle movement tendency index, The value range of is between 0 and 1. When is close to 1, it indicates that under the combined action of seabed current and waves, sediment particles are easily scoured, and the migration and deposition trends are obvious. When is close to 0, it indicates that under the combined action of seabed current and waves, sediment particles are not easily scoured, and the migration and deposition trends are weak.

[0033] A further improvement of the technical solution of the present invention lies in: in step 3, the calculation process of the scouring depth of the sediment around the submarine pipeline in the target sea area is as follows:

[0034] Traverse the hydrological, geological and sediment particle data of the target sea area in the sea area basic data sequence table. According to the seabed current velocity, wave height, sediment particle size distribution and sediment characteristics, combined with the interaction between the seabed current and waves, as well as the starting and transportation processes of sediment particles, analyze the sediment erosion rate around the submarine pipeline. Combine the seabed current velocity, wave characteristics, sediment particle characteristics and seabed topography factors, and analyze the sediment settlement process and deposition conditions to determine the sediment deposition rate around the submarine pipeline.

[0035] According to the flow direction and velocity of ocean currents and waves, as well as the starting and transportation characteristics of sediment particles, analyze the migration direction of sediment particles, and based on the sedimentation process and deposition conditions of sediment particles, analyze the deposition location of sediment particles;

[0036] Select a numerical simulation method that combines the computational fluid dynamics (CFD) method and the discrete element method (DEM). According to the characteristics of the target sea area and calculation requirements, determine the parameters and boundary conditions of the numerical simulation method, and combine the combined effects of ocean current scour, wave scour, and sediment particle movement, as well as the influence of seabed topography and sediment characteristics, to construct a scour depth estimation model based on the sediment erosion rate and deposition rate;

[0037] According to the model requirements, input the corresponding parameters, including ocean current velocity, wave height, sediment particle size distribution, sediment characteristics, and seabed topography, and use the numerical simulation method to calculate the actual scour depth of the sediment around the submarine pipeline in the target sea area, and verify and check the calculation results to ensure the accuracy and reliability of the results.

[0038] A further improvement of the technical solution of the present invention is that the calculation expression of the actual scour depth is:

[0039] ;

[0040] Wherein, is the actual scour depth, is the actual ocean current velocity (m / s), representing the ocean current velocity around the submarine pipeline, is the reference ocean current velocity (m / s), which is a preset reference value used to standardize the ocean current velocity, H is the actual wave height (m), representing the wave height around the submarine pipeline, is the reference wave height (m), is the median grain size of the sediment (m), is the reference sediment grain size (m), which is a preset reference value used to standardize the sediment grain size, is the density of sediment particles (kg / m³), representing the density of sediment particles, is the density of water (kg / m³), representing the density of water, S is the seabed topography slope (°), representing the slope of the seabed topography, is the reference seabed topography slope (°), which is a preset reference value used to standardize the seabed topography slope.

[0041] A further improvement of the technical solution of the present invention is that in step 4, the evaluation process of the abnormal state of the submarine pipeline under the scour effect is:

[0042] Extract relevant data on pipeline materials, pipeline dimensions, and design parameters from the collected pipeline information, and determine the pipeline diameter and reference diameter to analyze the stress threshold and deformation threshold of the subsea pipeline;

[0043] According to the pipeline material properties and design parameters, and in combination with relevant standards (such as API, ASME, etc.), determine the stress threshold of the pipeline, and then determine the actual pipeline stress and the yield strength threshold of the pipeline;

[0044] According to the pipeline dimensions, material properties, and design parameters, and in combination with the deformation limits during normal pipeline use, determine the deformation threshold of the pipeline, and then determine the elastic modulus of the pipeline material and the reference elastic modulus. The deformation threshold is related to the displacement and strain parameters of the pipeline and is used to evaluate the deformation of the pipeline under scouring;

[0045] Combined with the scouring depth analysis results and relevant pipeline standards, determine the actual scouring depth and scouring depth threshold, and based on the pipeline stress threshold and deformation threshold, comprehensively calculate the abnormal scouring state coefficient to evaluate the abnormal state of the subsea pipeline under scouring;

[0046] According to the magnitude of the abnormal scouring state coefficient, determine whether the subsea pipeline is in an abnormal scouring state. If the abnormal scouring state coefficient is less than the preset abnormal threshold, it is considered that the pipeline is in an abnormal scouring state, and for the pipeline in an abnormal scouring state, conduct a further stability assessment.

[0047] A further improvement of the technical solution of the present invention lies in: the calculation expression of the abnormal scouring state coefficient is:

[0048] ;

[0049] Wherein, is the abnormal scouring state coefficient, The value range of is between 0 and 1, is the actual scouring depth, obtained from the scouring depth analysis results, is the scouring depth threshold, related to the stability of the pipeline, E is the elastic modulus of the pipeline material, is the reference elastic modulus, used to standardize the elastic modulus, is the actual pipeline stress, calculated according to the pipeline stress situation, is the yield strength threshold of the pipeline, R is the pipeline diameter, is the reference diameter, used to standardize the pipeline diameter.

[0050] A further improvement of the technical solution of the present invention lies in: in the step 5, the process of sending out the risk warning information is:

[0051] According to the stress threshold and deformation threshold of the subsea pipeline, as well as the analysis results of the scouring depth, analyze the pipeline material, size, and design parameters, and the stress condition of the pipeline under scouring, and comprehensively evaluate the stability of the subsea pipeline;

[0052] According to the evaluation results, determine the stable state of the subsea pipeline, including stable, relatively stable, and unstable, and identify potential unstable factors and risk points;

[0053] According to the evaluation results of the subsea pipeline stability, conduct risk early warning and issue risk early warning information to relevant personnel. The risk early warning information includes the location of the risk point, risk level, possible influence range, and recommended preventive measures;

[0054] For the risk early warning results of the subsea pipeline stability, formulate targeted protective measures. Among them, for the unstable factors of the scour pit type, adopt measures such as rock throwing, artificial seagrass, and mattress protection to increase the support and stability of the pipeline. For the potential risks of the geological disaster type, strengthen geological monitoring and early warning and take timely response measures. For the risks of the external force damage type, strengthen pipeline inspection and maintenance, and timely discover and handle potential safety hazards;

[0055] Regularly monitor the state of the subsea pipeline, collect feedback information to evaluate the effectiveness of the protective measures, adjust the protection strategy according to the needs, and record all the processes of risk assessment, risk early warning information issuance, and protective measure implementation, and then compile a stability assessment report.

[0056] Due to the adoption of the above technical solution, the technical progress achieved by the present invention compared with the prior art is:

[0057] The present invention provides a method for discriminating the stability of a subsea pipeline based on the analysis of the subsea scouring mechanism. Through the analysis of the subsea scouring mechanism, accurately identify the risk areas around the pipeline that are vulnerable to scouring effects, and then conduct key monitoring and early warning on the risk areas, so as to strengthen protective measures in a targeted manner. And through continuous monitoring and analysis, dynamically evaluate the impact of scouring on the pipeline stability, can timely discover the pipeline deformation and stress concentration problems caused by scouring, and adjust the maintenance strategy accordingly, which not only improves the pertinence of safety protection, but also effectively saves resources and reduces maintenance costs.

[0058] The present invention provides a method for discriminating the stability of a subsea pipeline based on the analysis of the subsea scouring mechanism. Through the analysis of the subsea scouring mechanism, accurately evaluate the stability of the subsea pipeline under the influence of multiple factors such as geology, hydrology, and the pipeline itself, be able to clarify the loss situation of sediments around the pipeline, timely identify the risks that may affect the pipeline stability, and thus take corresponding protective measures to improve the safety and reliability of the pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other accompanying drawings can also be obtained based on these drawings.

[0060] Figure 1 It is the method flowchart of the present invention;

[0061] Figure 2 It is the analysis flowchart of the migration and deposition trend of sediment particles of the present invention;

[0062] Figure 3 It is the calculation flowchart of the scouring depth of the sediment around the submarine pipeline in the target sea area of the present invention;

[0063] Figure 4 It is the evaluation flowchart of the abnormal state of the submarine pipeline under scouring action of the present invention. Specific Embodiments

[0064] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0065] Embodiment 1, as Figures 1 to 3 shown, the present invention provides a method for discriminating the stability of a submarine pipeline based on the analysis of the submarine scouring mechanism, including the following steps:

[0066] Step 1: Obtain the basic data of the target sea area, including the geological information of the area where the submarine pipeline is located, the hydrological information of the sea area near the pipeline, and the pipeline information. According to the specific location and orientation of the submarine pipeline, delimit the sea area range where data needs to be collected, and identify the key nodes such as pipeline turning points, intersection points, and deep-water areas, as well as the potential risk areas in geological disaster-prone areas and waterway intersection areas, which are used as the key positions for data collection. Use geological exploration technology (gravity exploration) to obtain the geological information of the seabed topography, stratigraphic structure, and sediment type, and consult historical geological data to obtain the geological changes, seismic activities, and fault distribution information of the target sea area. Use the data of existing ocean observation stations to obtain the hydrological information of tides, ocean currents, waves, temperature, and salinity in the sea area near the pipeline. Add hydrological monitoring stations at key positions for real-time monitoring to ensure the timeliness and accuracy of the data. Obtain the design drawings, construction records, and operation logs of the pipeline from the pipeline construction unit and operation unit, and extract the basic information of the pipeline (material, diameter, wall thickness, burial depth, anti-corrosion measures, etc.). Use a submarine pipeline detection device based on the CT principle to conduct non-destructive detection on the pipeline to obtain the operation status information of the pipeline wall thickness, defect distribution, and corrosion degree. Integrate the collected geological information, hydrological information, and pipeline information to form a sea area basic data sequence table. The sea area basic data sequence table includes the name, source, time, location, and numerical information of the data, and verify the integrated data to ensure the accuracy, integrity, and consistency of the data. Store the relevant data of the sea area basic data sequence table in the database;

[0067] Step 2: Conduct feature analysis on the basic data of the target sea area, extract the characteristic data related to sea current scouring, wave scouring, and sediment particle movement, analyze the migration and deposition trends of sediment particles under the condition of seabed scouring, extract the basic data sequence list of the sea area from the database, and conduct feature analysis on the basic data of the target sea area in the basic data sequence list of the sea area. Respectively extract the characteristics related to sea current scouring, wave scouring, and sediment particle movement. Based on the hydrological information data in the basic data sequence list of the sea area, determine the parameters of sea current velocity, direction, wave height, period, and direction to analyze the sea current scouring characteristics and wave scouring characteristics. And according to the geological information data, determine the parameters of sediment particle size distribution, density, and permeability to analyze the sediment particle movement characteristics. Extract the parameters of sea current velocity and direction, determine the characteristic values of sea current scouring force and sea current power. Extract the parameters of wave height, period, and direction from the wave data, determine the characteristic values of wave dynamic pressure and shear force. According to the determined parameters of sediment particle size distribution, density, and permeability, determine the characteristic values of sediment erosion rate and deposition rate. Based on the characteristic values of sea current scouring force and sea current power, combined with the sediment characteristics, calculate the sea current scouring tendency index, analyze the scouring trend of the sea current on sediment particles, clarify the migration direction and intensity of sediment particles under the action of sea current scouring. Based on the characteristic values of wave dynamic pressure and shear force, combined with the sediment characteristics, calculate the wave scouring tendency index, analyze the scouring trend of waves on seabed sediments, clarify the migration direction and intensity of sediment particles under the action of wave scouring. Superimpose and analyze the sea current scouring tendency index and the wave scouring tendency index, comprehensively consider the interaction between sea current and waves, calculate the sediment particle movement tendency index, and comprehensively analyze the migration and deposition trends of sediment particles under the combined action of sea current and waves;

[0068] Further, the expression of the sea current scouring tendency index is:

[0069] ;

[0070] Wherein, is the sea current scouring tendency index, The value range of is between 0 and 1, is the actual sea current scouring force, calculated based on the sea current velocity, direction, and sediment characteristics, is the reference sea current scouring force, which is a preset reference value used to standardize the sea current scouring force. V is the actual sea current velocity, is the reference sea current velocity, corresponding to , is the median grain size of the sediment, is the reference sediment grain size, which is a preset reference value used to standardize the grain size, is the sediment particle density, is the water density. When When it is close to 1, it indicates that the seabed current scouring force is strong, and sediment particles are easily scoured. When it is close to 0, it indicates that the seabed current scouring force is weak, and sediment particles are not easily scoured. By combining the seabed current scouring force with sediment characteristics, the logarithmic function and radical are used to describe the influence of seabed current velocity and sediment particle size on the scouring trend, comprehensively evaluate the scouring trend of the seabed current on sediment particles, and by comparing the actual value with the reference value, quantify the direction and intensity of sediment particle migration under the action of seabed current scouring to evaluate the influence of seabed current scouring on the stability of submarine pipelines in a specific sea area;

[0071] The expression of the wave scouring tendency index is:

[0072] ;

[0073] Among them, is the wave scouring tendency index, the value range of is between 0 and 1, is the actual wave dynamic pressure, which is calculated according to the wave height, period and direction, is the reference wave dynamic pressure, which is a preset reference value used to standardize the wave dynamic pressure, is the actual wave shear force, which is calculated according to the wave characteristics and sediment characteristics, is the reference wave shear force, which is a preset reference value used to standardize the shear force. When it is close to 1, it indicates that the wave scouring force is strong, and sediment particles are easily scoured. When it is close to 0, it indicates that the wave scouring force is weak, and sediment particles are not easily scoured. By combining the wave dynamic pressure and shear force, the logarithmic function and radical are used to describe the influence of wave characteristics and sediment particle size on the scouring trend, comprehensively evaluate the scouring trend of waves on seabed sediments, and by comparing the actual value with the reference value, quantify the direction and intensity of sediment particle migration under the action of wave scouring to evaluate the influence of wave scouring on the stability of submarine pipelines in a specific sea area;

[0074] The expression of the sediment particle movement tendency index is:

[0075] ;

[0076] Among them, is the sediment particle movement tendency index, the value range of is between 0 and 1, is the seabed current scouring tendency index, which reflects the scouring trend of the seabed current on sediment particles, is the wave scouring tendency index, which reflects the scouring trend of waves on seabed sediments. When When it is close to 1, it indicates that sediment particles are easily scoured under the combined action of ocean currents and waves, and the migration and deposition trends are obvious. When When it is close to 0, it indicates that sediment particles are not easily scoured under the combined action of ocean currents and waves, and the migration and deposition trends are weak. By combining the ocean current scouring force and the wave scouring force, and using logarithmic functions and radicals to describe the influence of the characteristics of ocean currents and waves and the sediment particle size on the scouring trend, comprehensively evaluate the migration and deposition trends of sediment particles under the combined action of ocean currents and waves. Through the superposition analysis of the ocean current scouring tendency index and the wave scouring tendency index, quantify the direction and intensity of the migration of sediment particles under the combined action of ocean currents and waves, so as to evaluate the influence of ocean current and wave scouring on the stability of submarine pipelines in a specific sea area;

[0077] Step 3: Integrate the analysis results of ocean current scouring, wave scouring, and sediment particle movement to clarify the scouring depth of the sediment around the submarine pipeline in the target sea area. Traverse the hydrological, geological, and sediment particle data of the target sea area in the sea area basic data sequence table. According to the ocean current velocity, wave height, sediment particle size distribution, and sediment characteristics, combined with the interaction between ocean currents and waves, as well as the initiation and transportation processes of sediment particles, analyze the sediment erosion rate around the submarine pipeline. Combine the ocean current velocity, wave characteristics, sediment particle characteristics, and seabed topography factors, and analyze the sedimentation process and deposition conditions of sediment particles to determine the sediment deposition rate around the submarine pipeline. According to the flow direction and velocity of ocean currents and waves, as well as the initiation and transportation characteristics of sediment particles, analyze the migration direction of sediment particles, and according to the sedimentation process and deposition conditions of sediment particles, analyze the deposition position of sediment particles. Select a numerical simulation method that combines the computational fluid dynamics (CFD) method and the discrete element method (DEM). According to the characteristics of the target sea area and the calculation requirements, determine the parameters and boundary conditions of the numerical simulation method, and combine the combined action of ocean current scouring, wave scouring, and sediment particle movement, as well as the influence of seabed topography and sediment characteristics. Based on the sediment erosion rate and deposition rate, construct a scouring depth estimation model. According to the model requirements, input the corresponding parameters, including ocean current velocity, wave height, sediment particle size distribution, sediment characteristics, and seabed topography, and use the numerical simulation method for calculation to obtain the actual scouring depth of the sediment around the submarine pipeline in the target sea area. Verify and check the calculation results to ensure the accuracy and reliability of the results;

[0078] Furthermore, the calculation expression of the actual scouring depth is:

[0079] ;

[0080] Among them, is the actual scouring depth, indicating the actual scouring depth of the sediment around the submarine pipeline under specific conditions, $v$ is the actual sea current velocity (m / s), representing the sea current velocity around the submarine pipeline. $v_0$ is the reference sea current velocity (m / s), which is a preset reference value used to standardize the sea current velocity. $H$ is the actual wave height (m), representing the wave height around the submarine pipeline. $H_0$ is the reference wave height (m), which is a preset reference value used to standardize the wave height. $d_50$ is the median grain size of the sediment (m). $d_0$ is the reference sediment grain size (m), which is a preset reference value used to standardize the sediment grain size. $\rho_s$ is the sediment particle density ($kg / m^3$), representing the density of the sediment particles. $\rho$ is the water density ($kg / m^3$), representing the density of water. $S$ is the submarine terrain slope ($°$), representing the slope of the submarine terrain. $S_0$ is the reference submarine terrain slope ($°$), which is a preset reference value used to standardize the submarine terrain slope. When $v$ increases, the scour depth increases, indicating that the greater the sea current velocity, the more severe the scour. When $H$ increases, the scour depth increases, indicating that the greater the wave height, the more severe the scour. When $d_50$ increases, the scour depth decreases, indicating that the larger the sediment particles, the less likely they are to be scoured. When $S$ increases, the scour depth increases, indicating that the steeper the submarine terrain slope, the more severe the scour.

[0081] Step 4: Based on the pipeline information, obtain the stress threshold and deformation threshold of the submarine pipeline, and combine the analysis results of the scour depth to evaluate the abnormal state of the submarine pipeline under the scour action to judge the stability of the submarine pipeline.

[0082] Step 5: According to the evaluation results of the submarine pipeline stability, issue a risk warning message and formulate targeted protection measures.

[0083] Embodiment 2: As Figure 4 shown, on the basis of Embodiment 1, the present invention provides a technical solution: Preferably, in Step 4, the evaluation process of the abnormal state of the submarine pipeline under the scour action is as follows:

[0084] Extract relevant data on pipeline materials, pipeline dimensions, and design parameters from the collected pipeline information to determine the pipeline diameter and reference diameter for analyzing the stress threshold and deformation threshold of the subsea pipeline. Among them, understand the material composition and heat treatment process of the subsea pipeline through the pipeline material. The pipeline material affects the stress threshold of the pipeline. The pipeline dimensions include the pipeline diameter, wall thickness, etc., which are used to calculate the deformation threshold of the pipeline. Obtain the design pressure and design temperature of the pipeline through the design parameters to determine the stress condition of the pipeline under normal operating conditions. According to the pipeline material characteristics and design parameters, combined with relevant standards (such as API, ASME, etc.), determine the stress threshold of the pipeline, and then determine the actual pipeline stress and the yield strength threshold of the pipeline. The stress threshold is related to the yield strength, tensile strength of the pipeline, and the sensitivity of hydrogen-induced stress cracking. The stress threshold decreases with the increase of the alloy yield strength and tensile strength, and is affected by environmental temperature, hydrogen pressure, and purity factors. According to the pipeline dimensions, material characteristics, and design parameters, combined with the deformation limit during the normal use of the pipeline, determine the deformation threshold of the pipeline, and then determine the elastic modulus of the pipeline material and the reference elastic modulus. The deformation threshold is related to the displacement and strain parameters of the pipeline, and is used to evaluate the deformation of the pipeline under scouring. Combine the analysis results of the scouring depth and the relevant standards of the pipeline to determine the actual scouring depth and the scouring depth threshold, and based on the pipeline stress threshold and deformation threshold, comprehensively calculate the abnormal scouring state coefficient to evaluate the abnormal state of the subsea pipeline under scouring. According to the magnitude of the abnormal scouring state coefficient, judge whether the subsea pipeline is in an abnormal scouring state. If the abnormal scouring state coefficient is less than the preset abnormal threshold, it is considered that the pipeline is in an abnormal scouring state, and further stability assessment is carried out on the pipeline in the abnormal scouring state;

[0085] Furthermore, the calculation expression of the abnormal scouring state coefficient is:

[0086] ;

[0087] Wherein, is the abnormal scouring state coefficient, The value range of is between 0 and 1, is the actual scouring depth, obtained according to the analysis results of the scouring depth, is the scouring depth threshold, related to the stability of the pipeline, E is the elastic modulus of the pipeline material, is the reference elastic modulus, used to standardize the elastic modulus, is the actual pipeline stress, calculated according to the stress condition of the pipeline, is the yield strength threshold of the pipeline, R is the pipeline diameter, is the reference diameter, used to standardize the pipeline diameter. When is close to 1, it indicates that the scouring depth and stress level of the pipeline are close to the threshold, and the pipeline is in a normal state. When When it is close to 0, it indicates that the scouring depth or stress level of the pipeline far exceeds the threshold value, and the pipeline is in an abnormal state, and maintenance measures need to be taken;

[0088] In step 5, the process of issuing the risk warning information is as follows:

[0089] According to the stress threshold and deformation threshold of the submarine pipeline, as well as the scouring depth analysis results, analyze the pipeline material, size and design parameters, and the stress condition of the pipeline under scouring, comprehensively evaluate the stability of the submarine pipeline, and determine the stable state of the submarine pipeline according to the evaluation results, including stable, relatively stable, and unstable, and identify potential unstable factors and risk points. According to the evaluation results of the submarine pipeline stability, conduct risk warning and issue risk warning information to relevant personnel. The risk warning information includes the location of the risk point, the risk level, the possible influence range, and the recommended preventive measures. For the risk warning results of the submarine pipeline stability, formulate targeted protection measures. Among them, for the unstable factors of the scouring pit type, take measures such as rock throwing, artificial seagrass, and mattress protection to increase the support and stability of the pipeline. For the potential risks of the geological disaster type, strengthen geological monitoring and warning and take timely response measures. For the risks of the external force damage type, strengthen pipeline inspection and maintenance, timely discover and handle potential safety hazards, regularly monitor the state of the submarine pipeline, collect feedback information to evaluate the effect of the protection measures, adjust the protection strategy according to the needs, and record all the processes of risk assessment, risk warning information issuance and protection measure implementation, and then compile a stability assessment report.

[0090] As mentioned above, it is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claimed rights.

Claims

1. A method for determining the stability of a submarine pipeline based on the analysis of the submarine scour mechanism, characterized in that: The following steps are involved: Step 1, obtain the basic data of the target sea area, including the geological information of the area where the submarine pipeline is located, the hydrological information of the sea area near the pipeline, and the pipeline information, integrate the collected geological information, hydrological information and pipeline information to form a sea area basic data sequence table, where the sea area basic data sequence table contains the name, source, time, location, and numerical information of the data, and verify the integrated data, and store the relevant data of the sea area basic data sequence table in the database; Step 2: Perform feature analysis on the basic data of the target sea area, extract feature data related to current scouring, wave scouring and sediment particle movement, and analyze the migration and deposition trends of sediment particles under seabed scouring conditions. The analysis process of sediment particle migration and deposition trends is as follows: Extract the sea area basic data sequence table from the database, and perform feature analysis on the target sea area basic data in the sea area basic data sequence table, and extract the features related to current scouring, wave scouring and sediment particle movement respectively; Based on the hydrological information data in the sea area basic data sequence table, determine the parameters of ocean current speed, direction, wave height, period, and direction to analyze the ocean current scouring characteristics and wave scouring characteristics, and based on the geological information data, determine the parameters of sediment particle size distribution, density, and permeability to analyze the movement characteristics of sediment particles; Extract the parameters of ocean current speed and direction, determine the characteristic values ​​of ocean current scouring force and ocean current power, extract the wave height, period, and direction parameters from the wave data, determine the characteristic values ​​of wave dynamic pressure and shear force, and determine the characteristic values ​​of sediment erosion rate and deposition rate based on the determined sediment particle size distribution, density, and permeability parameters; Based on the characteristic values ​​of ocean current scouring force and ocean current power, combined with sediment characteristics, the ocean current scouring trend index is calculated to analyze the scouring trend of ocean current on sediment particles, and to clarify the migration direction and intensity of sediment particles under the action of ocean current scouring; Based on the characteristic values ​​of wave dynamic pressure and shear force, combined with sediment characteristics, the wave scouring trend index is calculated to analyze the scouring trend of waves on seabed sediments and clarify the migration direction and intensity of sediment particles under wave scouring. The current scouring trend index and the wave scouring trend index are superimposed and analyzed, the interaction between current and wave is integrated, the sediment particle movement trend index is calculated, and the migration and deposition trend of sediment particles under the combined action of current and wave are comprehensively analyzed; Step 3: Based on the analysis results of current scouring, wave scouring and sediment particle movement, the scouring depth of sediments around the submarine pipeline in the target sea area is determined; Step 4: Obtain the stress threshold and deformation threshold of the submarine pipeline based on the pipeline information, and evaluate the abnormal state of the submarine pipeline under the scouring action in combination with the analysis result of the scouring depth, so as to determine the stability of the submarine pipeline; Step 5: Based on the assessment results of submarine pipeline stability, issue risk warning information and formulate targeted protective measures.

2. A method for determining the stability of a submarine pipeline based on the analysis of the submarine scour mechanism according to claim 1, characterized in that: In step 1, the process of acquiring the basic data of the target sea area is as follows: According to the specific location and direction of the submarine pipeline, the sea area where data needs to be collected is delineated, and the turning points, intersections, key nodes in deep water areas, as well as potential risk areas in areas prone to geological disasters and channel intersections are identified as key locations for data collection; Use geological exploration technology to obtain geological information on seabed topography, stratigraphic structure, and bottom type, and consult historical geological data to obtain information on geological changes, seismic activity, and fault distribution in the target sea area. Use data from existing ocean observation stations to obtain hydrological information on tides, currents, waves, temperature, and salinity in the sea area near the pipeline; Obtain the pipeline design drawings, construction records, and operation logs from the pipeline construction unit and operation unit, extract the basic information of the pipeline, and use the submarine pipeline inspection device based on the CT principle to perform non-destructive inspection on the pipeline to obtain the operating status information of the pipeline wall thickness, defect distribution, and corrosion degree.

3. A method for determining the stability of a submarine pipeline based on the analysis of the submarine scour mechanism according to claim 2, characterized in that: The expression of the ocean current scouring tendency index is: Among them, I sc is the ocean current scouring trend index, F sc is the actual ocean current scouring force, F ref is the reference current scouring force, V is the actual current velocity, V ref is the reference current speed, and F ref Correspondingly, D 50 is the median particle size of the sediment, D ref is the reference sediment particle size, ρ s is the density of sediment particles, ρ is the water density, when I sc When it is close to 1, it means that the ocean current is strong and the sediment particles are easily washed away. sc When it is close to 0, it means that the scouring force of the ocean current is weak and the sediment particles are not easily scoured; The expression of the wave scour tendency index is: Among them, I wv is the wave scouring tendency index, P dp is the actual wave dynamic pressure, P ref is the reference wave dynamic pressure, τ sh is the actual wave shear force, τ ref is the reference wave shear force, when I wv When it is close to 1, it means that the wave scouring force is strong and the sediment particles are easily washed away. wv When it is close to 0, it means that the wave scouring force is weak and the sediment particles are not easily scoured; The expression of the sediment particle movement trend index is: Among them, I s is the sediment particle movement trend index, when I s When it is close to 1, it means that the sediment particles are easily washed away by the combined action of currents and waves, and the migration and deposition trends are obvious. s When it is close to 0, it means that the sediment particles are not easily washed away by the combined action of currents and waves, and the migration and deposition trends are weak.

4. A method for determining the stability of a submarine pipeline based on the analysis of the submarine scour mechanism according to claim 3, characterized in that: In step 3, the calculation process of the scouring depth of the sediments around the submarine pipeline in the target sea area is: Traverse the hydrological, geological and sediment particle data of the target sea area in the sea area basic data sequence table, analyze the sediment erosion rate around the submarine pipeline based on the current speed, wave height, sediment particle size distribution and sediment characteristics, combined with the interaction of current and waves, and the start-up and transportation process of sediment particles, and determine the sediment deposition rate around the submarine pipeline by combining the current speed, wave characteristics, sediment particle characteristics and seabed topography factors, and analyzing the sedimentation process and deposition conditions of sediment particles; Analyze the migration direction of sediment particles according to the direction and speed of ocean currents and waves and the starting and transport characteristics of sediment particles, and analyze the deposition location of sediment particles according to the sedimentation process and deposition conditions of sediment particles; Select a numerical simulation method that combines computational fluid dynamics and discrete element method, determine the parameters and boundary conditions of the numerical simulation method according to the characteristics of the target sea area and the calculation requirements, and build a scouring depth estimation model based on sediment erosion rate and deposition rate in combination with the combined effects of current scouring, wave scouring and sediment particle movement, as well as the influence of seabed topography and sediment characteristics; According to the model requirements, the corresponding parameters are input, including current velocity, wave height, sediment particle size distribution, sediment characteristics and seabed topography, and numerical simulation methods are used for calculation to obtain the actual scouring depth of sediments around the submarine pipeline in the target sea area.

5. A method for determining the stability of a submarine pipeline based on the analysis of the submarine scour mechanism according to claim 4, characterized in that: The calculation expression of the actual scouring depth is: Among them, h sc is the actual scouring depth, U c is the actual ocean current speed, U ref is the reference current speed, H is the actual wave height, H ref is the reference wave height, D 50 is the median particle size of the sediment, D ref is the reference sediment particle size, ρ s is the density of sediment particles, ρ is the water density, S is the seafloor topography slope, S ref is the base seafloor topography slope.

6. A method for determining the stability of a submarine pipeline based on the analysis of the submarine scour mechanism according to claim 5, characterized in that: In step 4, the evaluation process of the abnormal state of the submarine pipeline under the scouring effect is as follows: Extract relevant data on pipeline materials, pipeline dimensions and design parameters from the collected pipeline information, determine pipeline diameter and reference diameter to analyze stress threshold and deformation threshold of submarine pipeline; According to the pipeline material characteristics and design parameters, combined with relevant standards, the pipeline stress threshold is determined, and then the actual pipeline stress and pipeline yield strength threshold are determined; According to the size, material properties and design parameters of the pipeline, combined with the deformation limit of the pipeline during normal use, the deformation threshold of the pipeline is determined, and then the elastic modulus and reference elastic modulus of the pipeline material are determined; Combined with the scour depth analysis results and relevant pipeline standards, the actual scour depth and scour depth threshold are determined, and based on the pipeline stress threshold and deformation threshold, the abnormal scour state coefficient is comprehensively calculated to evaluate the abnormal state of the submarine pipeline under scour; According to the size of the abnormal scour state coefficient, it is judged whether the submarine pipeline is in an abnormal scour state. If the abnormal scour state coefficient is less than the preset abnormal threshold, it is considered that the pipeline is in an abnormal scour state, and further stability assessment is performed on the pipeline in the abnormal scour state.

7. A method for determining the stability of a submarine pipeline based on the analysis of the submarine scour mechanism according to claim 6, characterized in that: The calculation expression of the abnormal flushing state coefficient is: Among them, I abn is the abnormal scour state coefficient, I abn The value range is between 0 and 1. sc is the actual scouring depth, h st is the scour depth threshold, E is the elastic modulus of the pipeline material, and E ref is the reference elastic modulus, σ sc is the actual pipeline stress, σ yt is the yield strength threshold of the pipeline, R is the pipeline diameter, R ref is the reference diameter.

8. The method for determining the stability of a submarine pipeline based on the analysis of the submarine scour mechanism according to claim 7, characterized in that: In step 5, the process of issuing risk warning information is as follows: According to the stress threshold and deformation threshold of the submarine pipeline and the scouring depth analysis results, the pipeline material, size and design parameters as well as the stress of the pipeline under scouring are analyzed to comprehensively evaluate the stability of the submarine pipeline; Based on the assessment results, determine the stability status of the submarine pipeline, including stable, relatively stable, and unstable, and identify potential unstable factors and risk points; Based on the assessment results of submarine pipeline stability, risk warnings are issued to relevant personnel. The risk warning information includes the location of risk points, risk level, impact range, and recommended preventive measures; Formulate targeted protective measures based on the risk warning results of submarine pipeline stability; Regularly monitor the status of submarine pipelines and collect feedback information to evaluate the effectiveness of protective measures, adjust protection strategies as needed, and record all risk assessments, risk warning information issuance, and protection measures implementation processes to prepare stability assessment reports.

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