Seabed sand wave and pipeline interaction numerical simulation method and system and readable medium

Abstract

The invention relates to a seabed sand wave and pipeline interaction numerical simulation method and system and a readable medium. The method comprises the following steps: selecting a sub-model under an environment dynamic simulation model according to environment data; selecting a sub-model under the sediment transportation simulation model according to the seabed sediment data; whether a fatigue stability simulation model needs to be carried out is selected according to the pipeline type, if the pipeline is a rigid pipeline, the fatigue stability simulation model is not started, and otherwise, the fatigue stability simulation model is started; starting a sub-model of the protection and treatment simulation model; determining a computational domain of a numerical simulation model, adjusting grid boundary conditions through an environment dynamic simulation model, and combining all selected models to form a final numerical simulation model; and inputting to-be-tested material parameters and environmental parameters into the final numerical simulation model to obtain a seabed sand wave and pipeline interaction numerical simulation result. According to the method, a numerical simulation result which better conforms to the dynamic change process of the sand waves in a real environment can be obtained, and the dynamic change of the seabed sand waves can be better understood and predicted.

Description

Technical Field

[0001] The present invention relates to a numerical simulation method, system and readable medium for the interaction between submarine sand waves and pipelines, belonging to the technical field of submarine pipeline engineering. Background Technique

[0002] With the rapid development of economy and society, the shortage of energy and resources has become the main reason restricting its sustainable growth. The ocean is undoubtedly a treasure trove with huge potential, so countries have increased their efforts in developing ocean resources. As an important part of the offshore oil and gas field transportation system and an important form of submarine cable laying, submarine pipelines have many advantages such as large transportation volume, high efficiency, low loss, and all-weather operation, and thus are widely used in various projects.

[0003] Submarine sand waves are a terrain widely distributed globally, especially common on the seabed where nearshore hydrodynamic effects are obvious. Limited by resource distribution characteristics, topography and construction needs, many engineering structures have to cross or be built in areas with extensive sand waves. In recent years, on-site submarine observations have found that there are varying degrees of sand wave and sand ridge phenomena in multiple offshore oil and gas field areas, with wavelengths reaching hundreds of meters and wave heights reaching ten meters. Under the combined action of complex hydrodynamic forces such as waves, tides, internal waves, and even strong submarine currents caused by typhoons, these geological and geomorphic forms often exhibit significant activity, further leading to phenomena such as burial and suspension of submarine pipelines laid on sand wave ridges. The complex hydrodynamic conditions of the sand wave seabed may also change the development pattern of pipeline scour. Under the combined action of large-scale sand wave ridge migration and local scour below, the suspended section develops faster and the pattern is difficult to predict, ultimately possibly leading to flow-induced vibration, fatigue failure, and failure fracture of the pipeline, thus causing economic and environmental losses.

[0004] Existing research mainly focuses on the migration mechanism of sand wave ridges, but the research on the interaction mechanism between them and submarine pipelines is insufficient, resulting in the inability of traditional submarine pipeline design methods to handle special situations brought about by sand wave ridges. The standard submarine pipeline stability design is based on the assumption of a flat seabed and does not consider the impact of the suspension span caused by sand wave ridges on pipeline stability; while the conventional suspension span analysis method assumes that the suspension span position remains unchanged, so it is too conservative in predicting the fatigue life of the pipeline, significantly increasing the processing workload and cost. Summary of the Invention

[0005] Aiming at the above problems, the purpose of the present invention is to provide a numerical simulation method, system and readable medium for the interaction between submarine sand waves and pipelines, which can obtain numerical simulation results that are more in line with the dynamic change process of sand waves in the real environment, can better understand and predict the dynamic changes of submarine sand waves, and thus provide a more reliable basis for the design and implementation of ocean engineering.

[0006] To achieve the above object, the present invention proposes the following technical solutions: A numerical simulation method for the interaction between submarine sand waves and pipelines, comprising the following steps: input all environmental dynamic simulation models, sediment transport simulation models, fatigue stability simulation models, and protection and treatment simulation models; select a sub-model under the environmental dynamic simulation model according to environmental data; select a sub-model under the sediment transport simulation model according to submarine sediment data; select whether to perform a fatigue stability simulation model according to the pipeline type. If the pipeline is a rigid pipeline, the fatigue stability simulation model is not started, otherwise the fatigue stability simulation model is started; start a sub-model of the protection and treatment simulation model according to the results of the fatigue stability simulation model; determine the computational domain of the numerical simulation model, adjust the grid boundary conditions through the environmental dynamic simulation model, and combine all selected models to form the final numerical simulation model; input the material parameters and environmental parameters to be measured into the final numerical simulation model to obtain the numerical simulation results of the interaction between submarine sand waves and pipelines.

[0007] Further, the environmental dynamic simulation model includes a surface wave sub-model, a tidal current sub-model, an internal wave bottom current sub-model, and a typhoon field sub-model; the sediment transport simulation model includes a suspended load proton sub-model, a bed load proton sub-model, a gravel sub-model, and a clay sub-model; the fatigue stability simulation model includes a subsidence deformation sub-model, a flow-induced vibration sub-model, a critical suspension span sub-model, and a fatigue life sub-model; the protection and treatment simulation model includes a bionic grass sub-model, a pile support sub-model, a trenching and backfilling sub-model, and a covering layer sub-model.

[0008] Further, the method for selecting a sub-model under the sediment transport simulation model according to submarine sediment data is as follows: judge whether the submarine sediment is non-cohesive. If it is cohesive, start the clay sub-model. If it is non-cohesive, judge whether the size of the sediment particles is greater than a threshold value. If it is greater than the threshold value, start the gravel sub-model; if the size of the sediment particles is less than or equal to the threshold value, start the suspended load proton sub-model and the bed load proton sub-model.

[0009] Further, the surface wave sub-model is used to simulate the generation of surface waves, simulate micro-amplitude waves, Stokes waves of the fifth order and below, cnoidal waves, and solitary waves, or generate irregular waves according to measured wave spectrum data or random methods; the tidal current sub-model is used to simulate the generation of currents, simulate unidirectional currents and reciprocating currents, or import the velocity information at each moment within the simulation time period according to measured data to generate a velocity change curve for simulating the residual current and tidal current in special waters; the internal wave bottom current sub-model is used to simulate the generation of internal wave bottom currents, obtain periodic impact instantaneous velocities according to measured or non-hydrostatic ocean models, and import them into the internal wave bottom current sub-model to generate an internal wave bottom current change curve for simulating the internal wave bottom current field in specific waters; the typhoon field sub-model generates wind field data according to the approximate trajectory of the typhoon and its wind speed and air pressure at each moment point, corrects the outflow and wave data, and is used to simulate the typhoon wind field and the influence of water level rise and fall in the storm surge over-layer.

[0010] Furthermore, the suspended sediment model calculates the bed shear stress and particle settling velocity of sediment, and combines the convection-diffusion equation of particle concentration to calculate the suspension and settling fluxes of suspended sediment; in the bed load model, by calculating the balance of the drag force and lift force of sediment particles, its movement pattern is judged, the state migration between bed material load, bed load and saltation load is analyzed, and the bed load transport coefficient per unit width is calculated by the Meyer-Peter formula. Combining the suspended sediment model and the mass conservation equation of topographic evolution to simulate the sand wave migration and pipeline scouring process of non-cohesive sediment; in the gravel model, the Lagrangian particle characteristics of both smooth particle flow and discrete element are adopted, and based on the calculation method of boundary force at the fluid-solid interface, the bed load transport rate is calculated. Due to the large scale of gravel particles and the non-smooth seabed interface, smooth reconstruction is required after each time step; in the clay model, it is applicable to the soil characteristics with extremely fine particles and there is molecular viscous force between particles. Once the molecular force disappears, it is difficult to regenerate in a short time. Therefore, once such soil is suspended, it is difficult to deposit again. Therefore, a one-way bed erosion model is adopted to predict the development of the bed surface:

[0011]

[0012] where E is the erosion rate, τ cr is the critical shear stress, τ b is the actual shear stress of the bed surface, and a1, a2, a3 and M are empirical coefficients. When the calculated bed shear stress exceeds the sediment condition threshold, it is separately activated to calculate the local scour under clay conditions.

[0013] Furthermore, in the subsidence deformation sub-model, the pipeline scour simulation and the pipeline deformation simulation are decoupled, and the pipeline deformation of complex supports and structures is simulated; the flow-induced vibration sub-model is coupled by a flow field-vortex-induced vibration-scour model. The model adopts the virtual spring method, and the pipeline vibration is simulated by adding elastic supports to constrain the pipeline. At the same time, the forced vibration of the pipeline in both horizontal and vertical directions is simulated; in the critical free span sub-model, the Morison formula is used to calculate the wave force acting on the submarine pipeline. By comprehensively analyzing the self-weight, buoyancy and wave force of the pipeline, the stress distribution of the pipeline under different conditions is determined. At the same time, the critical free span of the pipeline is calculated in combination with the allowable stress of the pipeline; in the fatigue life sub-model, each section of the pipeline is screened by the in-line and cross-flow fatigue formulas of the free span, and the fatigue analysis is carried out on the pipe sections that do not meet the standards, and the fatigue life of the pipeline is calculated.

[0014] Furthermore, in the bionic grass seed model, the flexible bionic grass is generalized as a porous medium to simulate the scouring process of the bed surface with a flexible submerged bionic grass bed, and the protection effects of bionic grasses with different densities are simulated by adjusting the porosity of the porous medium; in the pile support sub-model, based on the pipe-soil coupling, the support pile is transformed into a conditional constraint to establish a numerical analysis model of the free-span pipe; the protection effect of the support pile is analyzed through the pipeline sinking condition or vortex-induced vibration; different sediment conditions are set in the trenching and backfilling sub-model to simulate the backfilled sand, or the model parameters are adjusted to simulate the dumped sandbag, and the protection and treatment effect of the sandbag is analyzed through the scouring development condition of the dumped sand or the displacement of the sandbag; the covering layer sub-model provides a variety of equations for simulating different material losses. Among them, the yield function of the concrete damage model uses the Lee and Fenves modified damage model; the incompressible third-order Ogden strain energy function is used for the hard rubber material; the Johnson-Cook viscoplastic model is used for the asphalt material; the damage of the fiber-reinforced composite material is based on the Hashin theory.

[0015] Furthermore, the numerical simulation results are visually displayed by generating contour maps of hydrodynamic parameters such as flow velocity and vorticity around the pipeline, bed shear stress distribution maps, and topographic profiles in any direction.

[0016] The present invention also discloses a numerical simulation system for the interaction between submarine sand waves and pipelines, including: a model input module for inputting all environmental dynamic simulation models, sediment transport simulation models, fatigue stability simulation models, and protection and treatment simulation models; a sediment transport simulation module for selecting a sub-model under the sediment transport simulation model according to the submarine sediment data; a fatigue stability simulation module for determining whether to perform the fatigue stability simulation model according to the pipeline type. If the pipeline is a rigid pipeline, the fatigue stability simulation model is not started, otherwise the fatigue stability simulation model is started; a protection and treatment simulation module for starting a sub-model of the protection and treatment simulation model according to the results of the fatigue stability simulation model; an environmental dynamic simulation module for determining the computational domain of the numerical simulation model, adjusting the grid boundary conditions through the environmental dynamic simulation model, and combining all selected models to form the final numerical simulation model; an output module for inputting the material parameters to be measured and environmental parameters into the final numerical simulation model to obtain the numerical simulation results of the interaction between submarine sand waves and pipelines.

[0017] The present invention also discloses a computer-readable storage medium, on which a computer program is stored, and the computer program is executed by a processor to implement the numerical simulation method for the interaction between submarine sand waves and pipelines described in any one of the above.

[0018] The technical solution of the present invention has at least the following technical effects or advantages:

[0019] 1. Based on effectively simulating complex hydrodynamic conditions, the method of the present invention obtains numerical simulation results that are more in line with the dynamic change process of sand waves in the real environment, enabling a better understanding and prediction of the dynamic changes of submarine sand waves, and thus providing a more reliable basis for the design and implementation of ocean engineering.

[0020] 2. The present invention combines the two factors of sand wave migration and local scour, explores their contributions to the progress of pipeline suspension and the variation law of suspension length, provides a more comprehensive understanding for the analysis and prediction of pipeline suspension phenomena, and improves the accuracy of pipeline integrity assessment and protection strategies.

[0021] 3. By designing different sediment transport simulation modules, the present invention simulates different bed conditions, thereby being able to more accurately simulate the development process of sand wave migration and pipeline local scour, contributing to a more comprehensive understanding and prediction of the dynamic behavior of submarine sediment, and thus enhancing the safety and reliability of submarine pipeline engineering. The present invention can generate a sand wave seabed model according to measured sand wave topography or specified parameters such as sand wave asymmetry coefficient, and the relative positions of the pipeline and sand waves can also be flexibly adjusted.

[0022] 4. While ensuring the calculation accuracy, the present invention realizes the decoupled calculation of the scour model and pipeline deformation, thus effectively shortening the numerical simulation time, enabling real-time monitoring of the deformation and force change processes of any component of the pipeline at any time and position, as well as outputting the change processes of any cross-section and the whole, making it easier to be displayed and analyzed.

[0023] 5. The present invention can simultaneously enable different sub-modules to comprehensively analyze the effects of various protection and treatment measures, with a wide application range and strong flexibility. Combined with different fatigue stability simulation modules, it can intuitively display the effects of different protection and treatment measures on pipeline settlement, vortex-induced vibration, critical suspension span, and fatigue life, thereby providing more accurate pipeline integrity assessment and protection strategies. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flowchart of a numerical simulation method for the interaction between submarine sand waves and pipelines in an embodiment of the present invention;

[0025] Figure 2 is a schematic structural diagram of a calculation model included in the numerical simulation method in an embodiment of the present invention;

[0026] Figure 3 is a schematic three-dimensional model diagram of a sand wave seabed (a) and a submarine pipeline (b) in an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail through specific embodiments. However, it should be understood that the provision of specific embodiments is only for better understanding of the present invention, and they should not be construed as limitations on the present invention. In the description of the present invention, it should be understood that the terms used are only for the purpose of description and cannot be construed as indicating or implying relative importance.

[0028] In order to solve the problems existing in the prior art that the standard submarine pipeline stability design is based on the assumption of a flat seabed and does not consider the influence of the span caused by sand waves and sand ridges on the pipeline stability; while the conventional span analysis method assumes that the span position remains unchanged, so it is too conservative in predicting the fatigue life of the pipeline, significantly increasing the processing workload and cost, etc., the present invention provides a numerical simulation method, system and readable medium for the interaction between submarine sand waves and pipelines. By introducing multiple calculation models, it simulates complex hydrodynamic conditions such as internal wave bottom currents and typhoon flow fields, and simulates complex sediment conditions such as clay and gravel; thus, a reasonable simulation of the sand waves and sand ridges on the seabed that conforms to the actual site is carried out, a suitable protection and treatment method is selected according to the simulation results, and the effects of one or more selected protection and treatment methods are predicted. Combining the predictions of different sand wave terrains and pipeline laying angles, a numerical simulation result of the interaction between submarine sand waves and pipelines is generated. The present invention combines two factors of sand wave migration and local scour, explores their contributions to the progress of the pipeline suspension state and the variation law of the suspension length, provides a more comprehensive understanding for the analysis and prediction of the pipeline suspension phenomenon, and improves the accuracy of pipeline integrity assessment and protection strategies. The following elaborates on the solution of the present invention through embodiments with reference to the accompanying drawings.

[0029] Embodiment 1

[0030] This embodiment discloses a numerical simulation method for the interaction between submarine sand waves and pipelines, as Figure 1 shown, including the following steps:

[0031] S1 Input all environmental dynamic simulation models, sediment transport simulation models, fatigue stability simulation models and protection and treatment simulation models.

[0032] Use CAD software such as SolidWorks or CFD internal preprocessing software to model each component of the model, as Figure 2 shown, including environmental dynamic simulation models, sediment transport simulation models, fatigue stability simulation models and protection and treatment simulation models. Import the required models into the numerical simulation software and adjust the relative positions among the sand wave seabed, the pipeline and the required protection engineering facilities.

[0033] S2 Select a sub-model under the environmental dynamic simulation model according to the environmental data.

[0034] As Figure 2As shown, the environmental dynamic simulation model includes a surface wave sub-model, a tidal current sub-model, an internal wave bottom current sub-model, and a typhoon field sub-model.

[0035] In previous studies, the simulation of submarine sand waves mainly focused on tidal current and wave conditions. These two conditions are one of the main factors for the formation of sand waves, and the simulation methods are relatively simple. The tidal current pattern is usually approximately simulated using a sinusoidal varying flow velocity, while the wave conditions use relevant models to generate regular surface waves. However, the internal wave bottom current is different from the above situations. The internal wave bottom current not only has periodic characteristics but also has impact characteristics. Therefore, it is necessary to obtain the time history curve of the internal wave bottom current based on ocean observation data or non-hydrostatic ocean models, and call these measured data in numerical simulations to achieve complex internal wave bottom current forms. In addition, the simulation of the typhoon flow field also needs to set its change form based on relevant data. On the basis of effectively simulating these complex hydrodynamic conditions, numerical simulation data that more conforms to the dynamic change process of sand waves in the real environment can be obtained.

[0036] The surface wave sub-model is used to simulate and generate surface waves, simulate regular waves such as micro-amplitude waves, Stokes waves of the fifth order and below, cnoidal waves, and solitary waves, or generate irregular waves according to measured wave spectrum data or random methods; the tidal current sub-model is used to simulate and generate currents, simulate unidirectional currents and reciprocating currents, or import the flow velocity information at each moment within the simulation time period according to measured data to generate a flow velocity change curve, which is used to simulate the residual current and tidal current in special waters; the internal wave bottom current sub-model is used to simulate and generate internal wave bottom currents, obtain periodic impact instantaneous flow velocities according to measured or non-hydrostatic ocean models, and import them into the internal wave bottom current sub-model to generate an internal wave bottom current change curve, which is used to simulate the internal wave bottom current field in specific waters; the typhoon field sub-model generates wind field data according to the approximate trajectory of the typhoon and its wind speed and air pressure at each moment point, corrects the outflow and wave data, and is used to simulate the typhoon wind field and the impact of water level rise and fall in the storm surge over-layer.

[0037] In previous submarine sand wave experiments, it was usually assumed that the sand wave waveform was relatively regular, and the direction of its wave crest line was perpendicular to the direction of the hydrodynamic force, that is, it could be approximately simplified to a two-dimensional problem. However, actual sand waves are often scattered in distribution and have variable wave patterns, and submarine pipelines can also exist on sand waves at any angle. This embodiment can generate a sand wave seabed model according to measured sand wave topography or parameters such as specified sand wave asymmetry coefficients, and the relative positions of the pipeline and the sand wave can also be flexibly adjusted, as Figure 2 shown.

[0038] S3 Select a sub-model under the sediment transport simulation model according to the submarine sediment data.

[0039] Previous studies mainly focused on non - cohesive sediment bed conditions. By calculating the transport rates of bed - load and suspended - load sediments and combining with the sediment mass conservation equation, the changes in the bed surface were determined. However, the behavior of cohesive sediment is completely different. Research shows that during local scour of pipelines, cohesive sediment often does not exhibit both scouring and deposition simultaneously. Therefore, for the bed movement of cohesive sediment, the erosion rate is usually used to determine it. In addition, affected by the adhesion force, the applicable Shields parameter curve for cohesive sediment is also different. For large - sized sediments such as gravel, an independent bed - load sediment transport equation is also needed to determine its movement process, so a separate module is set for simulation.

[0040] The sediment transport simulation model includes a suspended - load sub - model, a bed - load sub - model, a gravel sub - model, and a clay sub - model.

[0041] The method for selecting a sub - model under the sediment transport simulation model according to seabed sediment data is as follows: Judge whether the seabed sediment is non - cohesive. If it is cohesive, start the clay sub - model. If it is non - cohesive, judge whether the size of sediment particles is greater than the threshold. If it is greater than the threshold, start the gravel sub - model; if the size of sediment particles is less than or equal to the threshold, start the suspended - load sub - model and the bed - load sub - model.

[0042] In the suspended - load sub - model, by calculating the bed shear stress and particle settling velocity of sediment and combining with the convection - diffusion equation of particle concentration, the suspension and settlement fluxes of suspended sediment are calculated; in the bed - load sub - model, by calculating the balance of the drag force and lift force of sediment particles, its movement pattern is judged, the state migration between bed - material sediment, bed - load sediment, and saltating sediment is analyzed, and the bed - load sediment transport coefficient per unit width is calculated by the Meyer - Peter formula. Combining with the suspended - load sub - model and the mass conservation equation of terrain evolution, the sand wave migration and pipeline scour process of non - cohesive sediment are simulated; in the gravel sub - model, the common Lagrangian particle characteristics of smooth particle flow and discrete element bodies are adopted, and based on the calculation method of boundary force at the fluid - solid interface, the bed - load sediment transport rate is calculated. Since the gravel particle size is large and the seabed interface is not smooth, smooth reconstruction needs to be carried out after each time step; in the clay sub - model, it is applicable to the soil characteristics with extremely fine particles and there is molecular adhesive force between particles. Once the molecular force adhesion disappears, it is difficult to regenerate in a short time. Therefore, once such soil is suspended, it is very difficult to deposit again. Therefore, a one - way bed erosion model is adopted to predict the development of the bed surface morphology:

[0043]

[0044] Among them, E is the erosion rate, τ cr is the critical shear stress, τ b is the actual shear stress of the bed surface, and a1, a2, a3, and M are empirical coefficients. When the calculated bed shear stress exceeds the sediment condition threshold, it is started separately to calculate the local scour under clay conditions.

[0045] S4 selects whether to start the fatigue stability simulation model according to the pipeline type. If the pipeline is a rigid pipeline, the fatigue stability simulation model is not started; otherwise, the fatigue stability simulation model is started.

[0046] In the past, research on the stress, strain and protection of submarine pipelines was mainly carried out through physical model tests. However, it was difficult to detect the deformation and force-bearing process inside the model in physical tests, and usually only the final macroscopic deformation and depression, or the deformation and force-bearing of the local area at the sensor position could be obtained. Through the numerical model established in this embodiment, the deformation and force-bearing change process of any time, position and component can be monitored in real time, and the change process of any cross-section and the whole can be output, making it easier to be displayed and analyzed.

[0047] The fatigue stability simulation model includes a subsidence deformation sub-model, a flow-induced vibration sub-model, a critical span sub-model and a fatigue life sub-model.

[0048] In the subsidence deformation sub-model, the pipeline scour simulation and the pipeline deformation simulation are decoupled. Therefore, the deformation of pipelines with complex supports and structures can be simulated, and the development process of local scour of the pipeline can be simulated. When the span reaches a certain length, the subsidence deformation of the pipeline is calculated, and then it is re-modeled and imported into the numerical model, and the above process is repeated continuously. This method realizes the decoupled calculation of the scour model and the pipeline deformation while ensuring the calculation accuracy, thus effectively shortening the time of numerical simulation. The pipeline deformation can be calculated by using finite element software such as Abaqus for the subsidence of pipelines under complex supports and structures; the flow-induced vibration sub-model is composed of a coupling of a flow field-vortex-induced vibration-scour model. The model adopts the virtual spring method, and the vibration of the pipeline is simulated by adding elastic supports to constrain the pipeline. At the same time, the forced vibration of the pipeline in both horizontal and vertical directions is simulated; in the critical span sub-model, the Morison formula is used to calculate the wave force acting on the submarine pipeline. Through the comprehensive analysis of the self-weight, buoyancy and wave force of the pipeline, the stress distribution of the pipeline under different conditions is determined. At the same time, the critical span of the pipeline is calculated in combination with the allowable stress of the pipeline; in the fatigue life sub-model, each section of the pipeline is screened through the fatigue formulas in the along-flow direction and cross-flow direction of the span, and the fatigue analysis is carried out on the pipe sections that do not meet the standards, and the fatigue life of the pipeline is calculated.

[0049] After the laying of submarine pipelines, the positions of the pipelines usually remain relatively fixed, while the migration of sand waves under hydrodynamic action may cause some parts of the pipelines to be buried, exposed or suspended. At the same time, when the sand wave migration and local scour act together, it is relatively complex to evaluate their respective roles and importance in the process of pipeline suspension. In this embodiment, two factors of sand wave migration and local scour are combined to explore their contributions to the progress of pipeline suspension state and the variation law of suspension length, providing a more comprehensive understanding for the analysis and prediction of pipeline suspension phenomena and improving the accuracy of pipeline integrity assessment and protection strategies.

[0050] S5 Start the sub-model of the protection and treatment simulation model according to the results of the fatigue stability simulation model.

[0051] The protection and treatment simulation module of this embodiment covers various pipeline local scour protection measures commonly seen in actual projects, including bionic grass, support piles, backfilled sand, dumped sandbags, and covering layers of various materials. In addition, different sub-modules can be enabled simultaneously in this embodiment to comprehensively analyze the effects of various protection and treatment measures, with a wide application range and strong flexibility. Combined with different fatigue stability simulation modules, this embodiment can intuitively display the effects of different protection and treatment measures on pipeline settlement, vortex-induced vibration, critical suspension span, and fatigue life, thus providing a more accurate pipeline integrity assessment and protection strategy.

[0052] The protection and treatment simulation model includes a bionic grass sub-model, a pile support sub-model, a trenching and backfilling sub-model, and a covering layer sub-model. In the bionic grass sub-model, the flexible bionic grass is generalized as a porous medium to simulate the scour process of the bed surface with flexible submerged bionic grass, considering inertial loss, assuming that the porous medium model has no influence on turbulence, and simulating the protection effects of bionic grass with different densities by adjusting the porosity of the porous medium; the pile support sub-model, based on the pipe-soil coupling analysis, converts the support pile into special condition constraints and establishes a numerical analysis model of the suspended pipeline; the protection effect of the support pile is analyzed through the pipeline settlement or vortex-induced vibration; in the trenching and backfilling sub-model, different sediment conditions are set to simulate backfilled sand, or the model parameters are adjusted to simulate dumped sandbags, and the protection and treatment effects of the sandbags are analyzed through the development of the scour of the dumped sand or the displacement of the sandbags; the covering layer sub-model provides a variety of equations for simulating the loss of different materials. Among them, the yield function of the concrete damage model uses the Lee and Fenves modified damage model; the incompressible third-order Ogden strain energy function is used for hard rubber materials; the Johnson-Cook viscoplastic model is used for asphalt materials; the damage of fiber-reinforced composite materials is based on the Hashin theory.

[0053] S6 Determine the computational domain of the numerical simulation model and adjust the grid boundary conditions through the environmental dynamic simulation model.

[0054] Construct the basic grid system of the model according to the model size, and determine the computational domain; adjust the appropriate grid size through the sensitivity analysis of relevant parameters. Enable the environmental dynamic simulation module to adjust the grid boundary conditions, and import the corrected hydrodynamic parameters generated by the wave, tidal current, internal wave bottom current, and typhoon field sub-modules. Based on the INPUT file for parameter input, input various material parameters and constitutive model parameters, including sand wave seabed, pipeline, protection and treatment components, etc. Set the environmental condition parameters, such as working water depth, initial flow velocity, etc. Run the calculation and output the information of each component in the model in the file formats of odb, dat, res, and fil. According to the different enabled modules, output the corresponding parameters, such as pipeline amplitude, stress distribution, critical suspension span, and deformation of the covering layer.

[0055] S7 Combine all the selected models to form the final numerical simulation model.

[0056] The numerical simulation results are visually displayed by generating contour maps of hydrodynamic parameters such as flow velocity and vorticity around the pipeline, distribution maps of bed shear stress, and topographic profiles in any direction.

[0057] S8 Input the material parameters and environmental parameters to be measured into the final numerical simulation model to obtain the numerical simulation results of the interaction between submarine sand waves and pipelines.

[0058] In this embodiment, the numerical simulation method is used to simulate the sinking deformation, vortex-induced vibration, critical suspension span, and fatigue life of the pipeline itself during the local scour process, solving many problems in previous studies. In addition, it also supports simulating the effects of pipeline protection and treatment measures such as bionic grass, support piles, trenching and backfilling, and covering layer. This enables it to predict the performance of the pipeline in a complex environment, helping to more deeply understand and prevent the potential risks brought by sand wave migration to submarine pipelines in engineering practice, thereby assisting in designing a safer and more stable pipeline and protection system.

[0059] Embodiment 2

[0060] Based on the same inventive concept, this embodiment discloses a numerical simulation system for the interaction between submarine sand waves and pipelines, including:

[0061] A model input module for inputting all environmental dynamic simulation models, sediment transport simulation models, fatigue stability simulation models, and protection and treatment simulation models.

[0062] A sediment transport simulation module for selecting a sub-model under the sediment transport simulation model according to the submarine sediment data.

[0063] A fatigue stability simulation module for determining whether to start the fatigue stability simulation model according to the pipeline type. If the pipeline is a rigid pipeline, the fatigue stability simulation model is not started; otherwise, the fatigue stability simulation model is started.

[0064] The protection and governance simulation module is used to start the sub-model of the protection and governance simulation model according to the results of the fatigue stability simulation model.

[0065] The environmental dynamics simulation module is used to determine the computational domain of the numerical simulation model and adjust the grid boundary conditions through the environmental dynamics simulation model.

[0066] Combine all the selected models to form the final numerical simulation model; the output module is used to input the material parameters and environmental parameters to be measured into the final numerical simulation model to obtain the numerical simulation results of the interaction between submarine sand waves and pipelines.

[0067] Embodiment 3

[0068] Based on the same inventive concept, this embodiment discloses a computer-readable storage medium, on which a computer program is stored, and the computer program is executed by a processor to implement the numerical simulation method for the interaction between submarine sand waves and pipelines in any one of the above.

[0069] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0070] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of the flows and / or blocks in the flowchart and / or block diagram can also be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the specified functions in Figure 1 one or more of the processes or multiple processes and / or blocks Figure 1 one or more of the blocks or multiple blocks.

[0071] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured product including an instruction device, and the instruction device implements the specified functions in Figure 1 one or more of the processes or multiple processes and / or blocks Figure 1 one or more of the blocks or multiple blocks.

[0072] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one process or multiple processes and / or one block or multiple blocks. Figure 1 one process or multiple processes and / or blocks Figure 1 or multiple blocks.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: still can modify the specific implementation manners of the present invention or make equivalent replacements. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention. The above content is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or replacements, which should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A numerical simulation method for the interaction between seabed sand waves and pipelines, characterized in that: The following steps are involved: Input all environmental dynamic simulation models, sediment transport simulation models, fatigue stability simulation models and protection and management simulation models; Select a sub-model under the environmental dynamics simulation model according to environmental data; Select a sub-model under the sediment transport simulation model based on the seabed sediment data; Select whether to perform a fatigue stability simulation model according to the pipeline type. If the pipeline is a rigid pipeline, the fatigue stability simulation model is not started. Otherwise, the fatigue stability simulation model is started. Start the sub-model of the protection and governance simulation model according to the results of the fatigue stability simulation model; Determine the computational domain of the numerical simulation model, adjust the grid boundary conditions through the environmental dynamic simulation model, and combine all selected models to form the final numerical simulation model; The material parameters to be tested and the environmental parameters are input into the final numerical simulation model to obtain the numerical simulation results of the interaction between seabed sand waves and pipelines.

2. The method for numerical simulation of interaction between seabed sand waves and pipelines according to claim 1, characterized in that: The environmental dynamic simulation model includes a surface wave sub-model, a tidal current sub-model, an internal wave bottom flow sub-model and a typhoon field sub-model; the sediment transport simulation model includes a suspended proton model, a displacement proton model, a gravel sub-model and a clay sub-model; the fatigue stability simulation model includes a sinking deformation sub-model, a flow-induced vibration sub-model, a critical suspended span sub-model and a fatigue life sub-model; the protection and management simulation model includes a bionic grass sub-model, a pile support sub-model, a trenching and backfilling sub-model and a covering layer sub-model.

3. The method for numerical simulation of interaction between seabed sand waves and pipelines as claimed in claim 2, characterized in that: The method for selecting a sub-model under the sediment transport simulation model based on the seabed sediment data is as follows: determine whether the seabed sediment is inviscid, if it is viscous, start the clay sub-model; if it is inviscid, determine whether the size of the sediment particles is greater than a threshold, if it is greater than the threshold, start the gravel sub-model; if the size of the sediment particles is less than or equal to the threshold, start the suspended proton model and the pushed proton model.

4. The method for numerical simulation of interaction between seabed sand waves and pipelines according to claim 2, characterized in that: The surface wave sub-model is used to simulate and generate surface waves, simulate micro-amplitude waves, fifth-order and lower Stokes waves, elliptical cosine waves and solitary waves, or generate irregular waves according to measured spectral data or random methods; the tidal current sub-model is used to simulate and generate flow, simulate unidirectional flow and reciprocating flow, or import the flow velocity information at each moment in the simulation time period according to measured data to generate a flow velocity change curve to simulate the residual flow and tidal current in special waters; the internal wave bottom flow sub-model is used to simulate and generate internal wave bottom flow, obtain periodic impact instantaneous flow velocity according to measured or non-hydrostatic ocean mode, import the internal wave bottom flow sub-model to generate an internal wave bottom flow change curve to simulate the internal wave bottom flow field in specific waters; the typhoon field sub-model generates wind field data according to the general trajectory of the typhoon and the wind speed and air pressure at each time point, and corrects the outflow and wave data to simulate the influence of typhoon wind field and increase and decrease of water in the storm surge layer.

5. The method for numerical simulation of interaction between seabed sand waves and pipelines according to claim 2, characterized in that: The suspended proton model calculates the suspension and settling flux of suspended sediment by calculating the bed shear stress and particle settling velocity of sediment, and combines the convection-diffusion equation of particle concentration; the drift proton model determines the motion morphology of sediment particles by calculating the drag force and lift force of sediment particles, and analyzes the state migration between bed sand and drift sediment and saltation sediment; it calculates the drift sediment transport coefficient within unit width by the Mayer-Peter formula, and simulates the sand wave transport and pipeline scouring process of incohesive sediment by combining the suspended proton model and the mass conservation equation of terrain evolution; the gravel sub-model adopts the Lagrangian particle characteristics common to smooth particle flow and discrete unit body, calculates the drift sediment transport rate based on the boundary force at the fluid-solid interface, and smoothly reconstructs the drift sediment transport rate for each time step; the clay sub-model is suitable for soils with extremely fine particles and molecular viscosity between particles, and adopts the bed unidirectional erosion model to predict the bed morphology development, and its calculation formula is: Where E is the erosion rate, τ cr is the critical shear stress, τ b is the actual shear force on the bed surface, a1, a2, a3 and M are all empirical coefficients.

6. The method for numerical simulation of interaction between seabed sand waves and pipelines according to claim 2, characterized in that: In the sinking deformation sub-model, the pipeline scouring simulation is decoupled from the pipeline deformation simulation, and the deformation of the pipeline with complex supports and structures is simulated; the flow-induced vibration sub-model is formed by coupling the flow field-vortex-induced vibration-scouring model. The model adopts the virtual spring method to constrain the pipeline by adding elastic supports to achieve the simulation of pipeline vibration, and simulates the forced vibration of the pipeline in both horizontal and vertical directions; in the critical span sub-model, the Morison formula is used to calculate the wave force acting on the submarine pipeline, and the stress distribution of the pipeline under different conditions is determined by comprehensive analysis of the pipeline's dead weight, buoyancy and wave force, and the critical span of the pipeline is calculated in combination with the required stress of the pipeline; in the fatigue life sub-model, the pipeline sections are screened by the fatigue formulas for the span in the downstream and transverse directions, and fatigue analysis is performed on the pipe sections that do not meet the standards to calculate the pipeline fatigue life.

7. The method for numerical simulation of interaction between seabed sand waves and pipelines according to claim 2, characterized in that: In the bionic grass sub-model, the flexible bionic grass is generalized into a porous medium to simulate the scouring process of a bed containing flexible submerged bionic grass, and the protective effect of bionic grass of different densities is simulated by adjusting the porosity of the porous medium; in the pile support sub-model, the support piles are converted into conditional constraints based on pipe-soil coupling, and a numerical analysis model of the suspended span pipe is established; the protective effect of the support piles is analyzed by the pipeline sinking or vortex-induced vibration; in the trenching and backfilling sub-model, different sediment conditions are set to simulate backfill sand, or the model parameters are adjusted to simulate the dumped sandbags, and the protective management effect of the sandbags is analyzed by the development of the dumped sand scouring or the displacement of the sandbags; the cover layer sub-model provides a variety of equations for simulating the loss of different materials, among which the yield function of the concrete damage model uses the Lee and Fenves modified damage model; the hard rubber material uses the incompressible third-order Ogden strain energy function; the asphalt material uses the Johnson-Cook viscoplastic model; and the damage of fiber-reinforced composite materials is based on the Hashin theory.

8. The method for numerically simulating the interaction between seabed sand waves and pipelines according to any one of claims 1 to 7, characterized in that: The numerical simulation results are visualized by generating cloud maps of hydrodynamic parameters such as flow velocity and vorticity around the pipeline, bed shear stress distribution maps, and terrain profiles in any direction.

9. A numerical simulation system for the interaction between seabed sand waves and pipelines, characterized in that: include: Model input module, used to input all environmental dynamic simulation models, sediment transport simulation models, fatigue stability simulation models and protection and management simulation models; Sediment transport simulation module, used to select a sub-model under the sediment transport simulation model according to the seabed sediment data; A fatigue stability simulation module is used to select whether a fatigue stability simulation model is required according to the pipeline type. If the pipeline is a rigid pipeline, the fatigue stability simulation model is not started, otherwise the fatigue stability simulation model is started; The protection and governance simulation module is used to start the sub-model of the protection and governance simulation model according to the results of the fatigue stability simulation model; The environmental dynamics simulation module is used to determine the computational domain of the numerical simulation model, adjust the grid boundary conditions through the environmental dynamics simulation model, and combine all selected models to form the final numerical simulation model; The output module is used to input the material parameters and environmental parameters to be tested into the final numerical simulation model to obtain the numerical simulation results of the interaction between seabed sand waves and pipelines.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is executed by a processor to implement the numerical simulation method for interaction between seabed sand waves and pipelines according to any one of claims 1 to 8.

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