A method for parametric evaluation of the blast resistance of a submarine pipeline

Abstract

The application relates to the field of petroleum engineering and discloses a seabed pipeline anti-blast performance parameterization evaluation method, which comprises the following steps: a parameterized finite element simulation model of seabed pipeline blast response is established; key parameters such as explosive equivalent, pipeline outer diameter, pipeline wall thickness and soil covering depth are set as variables to generate multiple groups of parameter combinations; numerical simulation calculation of each parameter combination is carried out based on the parameterized finite element simulation model, the final damage state is extracted when the structural response tends to be stable, and damage grade division is carried out according to steel pipe rupture, transportation medium leakage and recess depth; and a database or a damage limit capability quick reference table is constructed based on the parameter combination and the damage grade. The application realizes unified modeling and analysis of seabed pipeline anti-blast response under different conditions by establishing a parameterized finite element simulation model containing multiple pipeline types and working conditions and uniformly integrating explosive equivalent, structural parameters and environmental parameters into a parameter variable system.

Description

Technical Field

[0001] This invention relates to the field of petroleum engineering, and in particular to a parameterized evaluation method for the explosion-proof performance of subsea pipelines. Background Technology

[0002] Submarine pipelines are a crucial infrastructure for marine oil and gas transportation, widely used in marine oil and gas development and energy transmission. In complex marine environments, submarine pipelines may be subjected to explosive loads, such as underwater explosions or near-shore explosions.

[0003] In existing technologies, the analysis of the explosion resistance of subsea pipelines typically employs numerical simulation or empirical formula-based methods. Numerical simulation methods generally establish finite element models for a single pipeline structure or specific operating conditions, performing calculations and analyses by changing individual parameters. Empirical formula methods, on the other hand, are mostly based on existing experimental or historical data, estimating the response under specific conditions. In practice, numerical simulation models are often established separately for different pipeline types, employing different modeling methods for suspended and buried conditions, and independently setting parameters such as explosive equivalent, pipeline dimensions, burial depth, and water depth. These methods usually require repeated modeling for different operating conditions and conducting calculations and analyses under different parameter combinations.

[0004] However, in the process of realizing the technical solution of this application, the inventors of this application discovered that the above-mentioned prior art has at least the following technical problems: the existing methods lack the technical means to uniformly incorporate pipeline type, structural parameters, environmental parameters and explosion parameters into the same parameter system and perform correlation modeling, which results in the analysis models of different structural forms and different working conditions not having a unified expression method, and thus it is difficult to systematically analyze the explosion-resistant response of submarine pipelines under multi-parameter combination conditions. Summary of the Invention

[0005] To overcome the above shortcomings, this invention provides a parameterized evaluation method for the explosion-proof performance of subsea pipelines, aiming to improve the problem that existing technologies are unable to systematically analyze the explosion-proof response of subsea pipelines under multiple parameter combinations.

[0006] This invention provides the following technical solution: a parameterized evaluation method for the explosion resistance performance of subsea pipelines, comprising the following steps: S1. Establish a parameterized finite element simulation model for the explosion response of a subsea pipeline. The parameterized finite element simulation model is established by classifying the subsea pipeline into single-layer pipe, single-layer counterweight pipe, double-layer pipe and double-layer counterweight pipe according to the pipeline type, and into suspended pipeline and buried pipeline according to the working conditions. At the same time, the pipeline geometric model, material constitutive model, fluid-structure interaction boundary conditions and explosion load model are constructed in the model. S2. Set key parameters as variables, and generate multiple sets of parameter combinations based on the key parameters. The key parameters include explosive equivalent, pipe type, pipe outer diameter, pipe wall thickness, concrete counterweight layer thickness, cross-sectional void ratio, pipe pressure, transport medium type, soil cover depth and ambient water depth. S3. Based on the parametric finite element simulation model and the combination of multiple parameters, perform multi-condition numerical simulation calculations to obtain the dynamic response data of the subsea pipeline during the entire process of explosive load. S4. Based on the dynamic response data, when the response of the subsea pipeline structure tends to stabilize and the damage no longer develops, the final assessment time is determined, and the structural state corresponding to the final assessment time is taken as the final damage state; whether the steel pipe is ruptured or whether the transport medium is leaked is taken as the priority judgment basis, and when rupture or leakage occurs, it is judged as severe damage; when no rupture or leakage occurs, the depth of the indentation is taken as the damage judgment basis to classify the damage level of the subsea pipeline. S5. Based on the relationship between the multiple sets of parameter combinations obtained in steps S2 to S4 and the corresponding damage levels, construct a database or a quick reference table of damage limit capabilities that associates key parameters with damage levels.

[0007] Preferably, in step S1, the step of establishing a parameterized finite element simulation model of the subsea pipeline explosion response includes: Submarine pipelines are classified according to their type into single-layer pipes, single-layer counterweight pipes, double-layer pipes, and double-layer counterweight pipes. Submarine pipelines are classified according to their operating conditions into suspended pipelines and buried pipelines. Furthermore, corresponding parametric finite element simulation models were established for different pipeline types and operating conditions to form a unified model system covering multiple structural forms and multiple explosion conditions.

[0008] Preferably, in step S1, the step of establishing a parameterized finite element simulation model of the subsea pipeline explosion response further includes: Discrete modeling is performed on the steel pipe, concrete counterweight layer, reinforcing bars and filling material of the submarine pipeline. Among them, the steel pipe is simulated using shell elements, the concrete counterweight layer is simulated using solid elements, the reinforcing bars are simulated using beam elements, and the filling material is simulated using a foamed material model. Furthermore, the concrete counterweight layer is divided into multiple solid units along the thickness direction to improve the discrete resolution of thickness-direction stress and damage evolution under explosion.

[0009] Preferably, in step S1, the step of establishing a parameterized finite element simulation model of the subsea pipeline explosion response further includes: Establish fluid and solid domains, and establish fluid-structure interaction between the fluid and solid domains; Establish a contact relationship between the seabed soil and the subsea pipeline and set friction parameters; Symmetric boundary conditions are set on the symmetry plane of the fluid domain, non-reflective boundaries are set on the outer boundary of the fluid domain, and fixed constraints are set at the ends of the subsea pipeline. An explosion load model was established by filling the pipe with the initial volume fraction of explosives and gas. The positions of the explosives were set according to the suspended pipe and the buried pipe respectively, so as to form contact explosion and non-contact explosion loading modes.

[0010] Preferably, in step S2, the step of setting the key parameter as a variable includes: Explosive equivalent, pipe type, pipe outer diameter, pipe wall thickness, concrete counterweight layer thickness, cross-sectional void ratio, internal pressure, transport medium type, soil cover depth and ambient water depth are selected as a unified set of parameter variables. The parameter variables are then associated with the geometric model, material constitutive model, and boundary conditions in the parameterized finite element simulation model to achieve parameterized expression of the model.

[0011] Preferably, in step S2, the step of setting the key parameters as variables further includes: Multiple value ranges can be set for each parameter variable; Generate multiple sets of parameter combinations based on the combination relationships between different parameter variables; Each set of parameters is mapped to an independent calculation condition; For buried pipelines, an assessment parameter is constructed by combining the soil cover depth and explosive equivalent to characterize the explosive effect, and then used for damage assessment of buried pipelines.

[0012] Preferably, in step S3, the step of performing multi-condition numerical simulation calculations includes: Generate corresponding finite element input models for each combination of parameters; The explicit dynamic analysis solver is invoked to perform calculations on the finite element input model; The calculation process outputs the displacement response, stress response, strain response, and damage evolution of the subsea pipeline. The entire process of the explosion was tracked to obtain complete dynamic response data.

[0013] Preferably, in step S4, the step of classifying the damage level of the subsea pipeline includes: The dynamic response data is analyzed; Determine the assessment point at which the subsea pipeline structure's response tends to stabilize and damage no longer progresses; The structural state corresponding to the assessment time is taken as the final damage state.

[0014] Preferably, in step S4, the step of classifying the damage level of the subsea pipeline further includes: When a steel pipe ruptures or the transported medium leaks, the submarine pipeline is classified as severely damaged. When the steel pipe does not rupture and the transport medium does not leak, the minimum cross-sectional distance change at the location of the explosion on the submarine pipeline is taken as the indentation depth. The subsea pipeline is classified as slightly damaged or moderately damaged based on the depth of the indentation.

[0015] Preferably, in step S5, the step of constructing a database or a quick reference table for the correlation between key parameters and damage levels includes: Summarize the key parameters, dynamic response data, and damage levels corresponding to each calculation condition; Establish a mapping relationship between key parameters and damage levels; Store the mapping relationship in a database; A damage limit capability quick reference table is generated based on the database. The damage limit capability quick reference table is presented in the form of a parameter matrix and different damage levels are distinguished by different identifiers.

[0016] The present invention has the following beneficial effects: 1. This invention establishes a parameterized finite element simulation model that includes various pipeline types and operating conditions, and incorporates explosive equivalent, structural parameters and environmental parameters into a unified parameter variable system, thereby achieving unified modeling and analysis of the explosion-proof response of subsea pipelines under different conditions.

[0017] 2. Based on the dynamic response data of the entire explosion process, this invention extracts the final state after the structural response stabilizes, and combines the steel pipe rupture, medium leakage and dent depth to determine the damage, thus realizing a unified quantitative assessment of the damage results.

[0018] 3. This invention establishes a mapping relationship between parameter combinations and damage levels, and expresses it in the form of a database or quick reference table, so that the corresponding damage level result can be obtained directly after inputting key parameters. Attached Figure Description

[0019] Figure 1 This is a flowchart of a parameterized evaluation method for the explosion-proof performance of subsea pipelines proposed in this invention; Figure 2 This is a model diagram of a subsea pipeline for a parameterized evaluation method of the explosion-proof performance of subsea pipelines proposed in this invention. Figure 3 This is a model diagram of a subsea suspended pipeline for a parameterized evaluation method of the explosion-resistant performance of subsea pipelines proposed in this invention. Figure 4This is a model diagram of a subsea buried pipeline for a parameterized evaluation method of the explosion-proof performance of subsea pipelines proposed in this invention. Figure 5 This is a model boundary condition diagram for a parameterized evaluation method for the explosion-resistant performance of subsea pipelines proposed in this invention. Figure 6 This is a modeling diagram of explosives and natural gas for a parameterized evaluation method of the explosion-resistant performance of subsea pipelines proposed in this invention. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Reference Figures 1-6 This invention provides a parameterized evaluation method for the explosion resistance performance of subsea pipelines, comprising the following steps: S1. Establish a parametric finite element simulation model for the explosion response of subsea pipelines. The parametric finite element simulation model is established by classifying subsea pipelines into single-layer pipes, single-layer counterweight pipes, double-layer pipes and double-layer counterweight pipes according to pipe type, and into suspended pipes and buried pipes according to working conditions. At the same time, the pipeline geometric model, material constitutive model, fluid-structure interaction boundary conditions and explosion load model are constructed in the model. Preferably, in step S1, the steps for establishing a parameterized finite element simulation model of the subsea pipeline explosion response include: Submarine pipelines are classified according to their type into single-layer pipes, single-layer counterweight pipes, double-layer pipes, and double-layer counterweight pipes. Submarine pipelines are classified according to their operating conditions into suspended pipelines and buried pipelines. Furthermore, corresponding parametric finite element simulation models were established for different pipeline types and operating conditions to form a unified model system covering multiple structural forms and multiple explosion conditions.

[0022] Preferably, in step S1, the step of establishing a parameterized finite element simulation model of the subsea pipeline explosion response further includes: Discrete modeling is performed on the steel pipe, concrete counterweight layer, reinforcing bars and filling material of the submarine pipeline. Among them, the steel pipe is simulated using shell elements, the concrete counterweight layer is simulated using solid elements, the reinforcing bars are simulated using beam elements, and the filling material is simulated using a foamed material model. Furthermore, the concrete counterweight layer is divided into multiple solid units along the thickness direction to improve the discrete resolution of thickness-direction stress and damage evolution under explosion.

[0023] Preferably, in step S1, the step of establishing a parameterized finite element simulation model of the subsea pipeline explosion response further includes: Establish fluid and solid domains, and establish fluid-structure interaction between the fluid and solid domains; Establish a contact relationship between the seabed soil and the subsea pipeline and set friction parameters; Symmetric boundary conditions are set on the symmetry plane of the fluid domain, non-reflective boundaries are set on the outer boundary of the fluid domain, and fixed constraints are set at the ends of the subsea pipeline. An explosion load model was established by filling the pipe with the initial volume fraction of explosives and gas. The positions of the explosives were set according to the suspended pipe and the buried pipe respectively, so as to form contact explosion and non-contact explosion loading modes.

[0024] Specifically, the first step is to establish pipe type classification rules. A single-layer pipe is a single-layer steel pipe bearing structure; a single-layer counterweight pipe is a single-layer steel pipe with a concrete counterweight layer around its perimeter; a double-layer pipe is a double-layer load-bearing structure consisting of an inner and outer steel pipe; and a double-layer counterweight pipe is a double-layer steel pipe with a further concrete counterweight layer around its perimeter. For double-layer and double-layer counterweight pipes, if infill material is used in the interlayer, the corresponding infill area is simultaneously created in the model. Using this classification method, during geometric modeling, the corresponding component combinations can be automatically called based on the pipe type: a single-layer pipe includes steel pipe components; a single-layer counterweight pipe includes steel pipe components and a concrete counterweight layer component; a double-layer pipe includes an inner steel pipe component, an outer steel pipe component, and optional infill components; and a double-layer counterweight pipe includes an inner steel pipe component, an outer steel pipe component, a concrete counterweight layer component, reinforcing steel components, and optional infill components. This allows different structural forms to obtain corresponding geometric topologies within the same modeling process.

[0025] In step S1, a classification rule for the working conditions is also established. The suspended pipeline model characterizes the response of the suspended section of a subsea pipeline to a contact explosion, while the buried pipeline model characterizes the response of the buried subsea pipeline to an explosion on the soil surface. In the suspended pipeline model, the explosive is placed on the pipeline surface, and the explosive load is directly input into the structure through the pipe wall. In the buried pipeline model, the explosive is placed above the free boundary surface of the soil, and the explosive load is propagated through seawater to the soil surface and then through the soil to the pipeline. The differences between the two working conditions are not only reflected in the location of the explosive, but also in the fluid domain coverage method, the soil participation method, and the boundary treatment method. Therefore, separate rules are established in the parametric finite element simulation model.

[0026] During the geometric modeling phase, steel pipe components are modeled according to the pipe's outer diameter, wall thickness, and segment length. For single-layer pipes and single-layer counterweight pipes, only one layer of steel pipe is established; for double-layer pipes and double-layer counterweight pipes, both the inner and outer layers are established. To ensure consistency in subsequent parameter representation, the pressure-bearing steel pipes in single-layer and single-layer counterweight pipes, as well as the inner layer steel pipes in double-layer and double-layer counterweight pipes, are all considered for subsequent damage assessment. The concrete counterweight layer is constructed around the outer perimeter of the steel pipe, with its inner diameter determined by the outer surface of the outer steel pipe and its outer diameter determined by the thickness of the concrete counterweight layer. Reinforcing steel components are established according to the spatial distribution of longitudinal reinforcement and stirrups, preferably arranged along the pipe's axial and circumferential directions within the concrete counterweight layer. The filling material is located within the interlayer space formed by the double-layer structure, and its geometric boundary is jointly defined by the outer surface of the inner steel pipe and the inner surface of the outer steel pipe.

[0027] In a double-layer structure, the cross-sectional void ratio can be used as a geometric control parameter to characterize the spatial relationship between the inner and outer steel pipes. The cross-sectional void ratio is defined as the ratio of the outer diameter of the inner pipe to the inner diameter of the outer pipe, i.e.: ; in, The cross-sectional void ratio, The outer diameter of the inner tube. This refers to the inner diameter of the outer tube. By changing... The value of can be adjusted simultaneously to change the size of the double-layer pipe sandwich space, the volume of the filling material, and the overall cross-sectional characteristics of the double-layer structure.

[0028] In the discretization modeling stage, the steel pipe is simulated using shell elements. Shell elements are chosen because the wall thickness of the steel pipe is typically much smaller than its diameter, allowing shell elements to directly express the geometric and thickness properties of the pipe wall's mid-surface and to calculate membrane forces, bending moments, plastic strain, and local buckling deformation under explosive loading. The concrete counterweight layer is simulated using solid elements. Solid elements are used because the counterweight layer thickness is greater than the steel pipe wall thickness, and under explosive loading, the counterweight layer experiences thickness-direction stress wave propagation, local cracking, and crushing damage. The reinforcing steel is simulated using beam elements. Beam elements characterize the axial tensile, compressive, and bending responses of the reinforcing steel and can interact with the concrete counterweight layer through node coupling, embedded relationships, or shared constraints. The filling material is simulated using a foamed material model and discretized using solid elements to reflect its compressive deformation characteristics under explosive loading. These discretization methods correspond to the geometric and stress characteristics of different components.

[0029] The concrete counterweight layer is divided into multiple layers of solid elements along its thickness. Preferably, the thickness direction is divided into at least three layers of solid elements. The reason for using this discretization method is that when an explosive impact acts on the outer surface of the counterweight layer, the stress wave propagates along the thickness direction, and the stress state, plastic development, and damage evolution of the outer and inner layers are not the same. If only a single layer of solid elements is used in the thickness direction, it is difficult to distinguish the differences between crushing on the outside, internal transmission, and internal constraint of the counterweight layer; if multiple layers of solid elements are used, the response gradient in the thickness direction can be separated at the mesh scale, thereby providing basic data for subsequent damage evolution analysis.

[0030] In establishing the fluid and solid domains, the fluid domain includes at least the seawater region, the explosive region, and the gas region inside the pipe, while the solid domain includes at least the subsea pipeline and the seabed soil. The fluid domain is preferably established using ALE solid elements. With ALE, material flow and mesh movement within the elements can be handled independently, making it suitable for processes such as detonation product expansion, seawater shock wave propagation, and gas pressure within the pipe. In the solid domain, the seabed soil is preferably established using Lagrange solid elements, the steel pipe using Lagrange shell elements, and the concrete counterweight layer and filling material using Lagrange solid elements. By placing the fluid and solid domains in the same solution model, the load transfer process from the explosive to the seawater, from the seawater to the soil, and then from the soil to the pipeline, or directly from the explosive to the pipeline, can be calculated in subsequent solution stages. During the fluid-structure interaction (FSI) establishment phase, FSI conditions are set at the interface between the fluid and solid domains, allowing fluid pressure to be transferred to the solid surface, while the movement of the solid boundary can be fed back to adjacent fluid elements. This coupling relationship is used to describe the interaction between the blast shock wave and the pipeline and seabed soil. For the interaction between the seabed soil and the subsea pipeline, a contact relationship and friction parameters are also established. The contact relationship limits the mutual penetration between the soil and the pipeline; the friction parameters characterize the tangential resistance of the soil and pipeline surfaces. When the pipeline experiences local displacement, rebound, or indentation under the impact of an explosion, contact and friction jointly affect the force transmission between the pipeline and the surrounding soil.

[0031] During the boundary condition setting phase, symmetric boundary conditions are set on the symmetry plane. Symmetric boundary conditions are used in conjunction with the half-model to reduce the overall number of elements. The general form of the symmetric boundary condition is: ; in, Let the boundary node displacement vector be... The normal vector of the plane of symmetry. This condition indicates that the displacement of the boundary node in the normal direction is zero, thus satisfying the requirements of geometric and force mirror symmetry. A non-reflective boundary is set at the outer boundary of the fluid domain to reduce the influence of boundary reflected waves on the local analysis region. Fixed constraints are set at the ends of the subsea pipeline to limit the boundary support conditions of the local analysis model. For the suspended pipeline model, it is preferable to fix one end of the pipeline and set symmetric constraints on the plane of symmetry to form a local analysis configuration of cantilever explosion; for the buried pipeline model, it is preferable to apply boundary conditions matching the propagation direction only at the boundary of the intercepted region, so that the stress waves inside the soil can propagate within a limited area without producing significant unrealistic reflections.

[0032] In the explosion load modeling phase, the explosive and the gas inside the pipe are modeled using an initial volume fraction filling method. This modeling method involves pre-defining the explosive region and the gas region inside the pipe within the fluid domain, and specifying their initial volume fraction, density, internal energy, and state equation parameters. At the start of the solution process, the solver establishes the spatial distribution relationship between the explosive, seawater, and gas based on the initial volume fraction information. For suspended pipes, the explosive region is positioned in contact with the pipe surface to form a contact explosion condition; for buried pipes, the explosive region is located above the free boundary surface of the soil to form a non-contact explosion condition. By setting the explosive positions separately, two different load input methods can be covered within the same modeling framework.

[0033] TNT is preferred as the explosive, and the JWL equation of state is used to characterize the detonation product pressures. Its expression is: ; in, For the pressure of detonation products, Relative volume The internal energy per unit initial volume, , , , and These are the parameters for the explosive's equation of state. This equation of state describes the pressure decay and volume expansion of the detonation products after the explosive detonates, and serves as the load source for subsequent shock wave propagation calculations. For gases inside the pipe, an adiabatic gas model can be used. For seawater and oil media, an equation of state model can be used for characterization. The assignment of material model parameters is part of the material constitutive model establishment in step S1, and its function is to provide constitutive relations for each medium region for subsequent solver calculations.

[0034] In the specific establishment of the suspended pipeline model, a half-symmetric model is preferred. The distances from the pipeline center to the upper, lower, left, and right boundaries of the fluid domain are set according to the explosion influence range, ensuring that the propagation process of the shock wave near the pipeline is completely contained within the fluid domain. The soil region can cover only the area near the support of the suspended section and a local seabed area, without needing to extend further away from the explosion effect location, thus keeping the computational scale of the model controllable. In the specific establishment of the buried pipeline model, a local soil section is preferably selected based on the explosion influence range, and the fluid domain completely covers the selected soil section and extends it a predetermined distance above the free surface of the soil. This is used to represent the process of the underwater explosion wave propagating through seawater before acting on the soil surface. The burial depth is determined by the vertical distance from the pipeline axis to the free surface of the soil. This distance is used in step S1 for geometric position establishment and in step S2 as a parameterized variable in multi-condition combination.

[0035] The parametric finite element simulation model established through step S1 above allows different pipeline structures and different explosion conditions to be expressed under unified modeling rules. It also enables the geometric model, material constitutive model, fluid-structure interaction boundary conditions, and explosion load model to be updated synchronously with parameter changes, thus providing a unified model basis for subsequent parametric calculations.

[0036] S2. Set key parameters as variables and generate multiple sets of parameter combinations based on the key parameters. Key parameters include explosive equivalent, pipe type, pipe outer diameter, pipe wall thickness, concrete counterweight layer thickness, cross-sectional void ratio, pipe pressure, transport medium type, soil cover depth and ambient water depth. Preferably, in step S2, the step of setting the key parameters as variables includes: Explosive equivalent, pipe type, pipe outer diameter, pipe wall thickness, concrete counterweight layer thickness, cross-sectional void ratio, internal pressure, transport medium type, soil cover depth and ambient water depth are selected as a unified set of parameter variables. The parameter variables are then associated with the geometric model, material constitutive model, and boundary conditions in the parametric finite element simulation model to achieve a parametric representation of the model.

[0037] Preferably, in step S2, the step of setting the key parameters as variables further includes: Multiple value ranges can be set for each parameter variable; Generate multiple sets of parameter combinations based on the combination relationships between different parameter variables; Each set of parameters is mapped to an independent calculation condition; For buried pipelines, an assessment parameter is constructed by combining the soil cover depth and explosive equivalent to characterize the explosive effect, and then used for damage assessment of buried pipelines.

[0038] Specifically, in step S2, a unified set of parameter variables is first established. This unified set of parameter variables consists of explosive equivalent, pipe type, pipe outer diameter, pipe wall thickness, concrete counterweight layer thickness, cross-sectional void ratio, internal pipe pressure, transport medium type, overburden depth, and ambient water depth. The purpose of using a unified set of parameter variables is to ensure consistency in parameter source, parameter name, parameter meaning, and parameter application location for different operating conditions within the same batch of calculations, avoiding the use of different names or treatments for the same physical quantity in different models.

[0039] To facilitate model invocation, in this implementation, the above set of parameter variables can be written as a parameter vector: ; in, This is a vector of operating condition parameters; It is the equivalent of explosives; Pipe type; The outer diameter of the pipe; The thickness of the pipe wall; The thickness of the concrete counterweight layer; The cross-sectional void ratio; The pressure inside the pipe; The type of transport medium; This refers to the depth of soil cover. The environmental water depth is used as an example. By using parameter vector representation, each set of working conditions can be represented as a specific set of values ​​for the parameter vector, which facilitates subsequent working condition numbering, batch calling, and database aggregation.

[0040] In step S2, the parameters are functionally categorized. Explosive equivalent is a blast load parameter, used to characterize the explosion scale; pipe type is a structural topology parameter, used to determine the component combinations and model levels; pipe outer diameter, pipe wall thickness, concrete counterweight layer thickness, and cross-sectional void ratio are structural geometric parameters, used to control the geometric model dimensions; pipe pressure and transport medium type are internal operating condition parameters, used to control the state of the medium inside the pipe and the pressure state of the steel pipe; and soil cover depth and ambient water depth are external environmental parameters, used to control the pipe's burial location, sea area size, and blast wave propagation path. Through this categorization, different parameters can be applied to their respective model parts during subsequent association and assignment processes.

[0041] The parameters are associated with the geometric model, material constitutive model, and boundary conditions in the parametric finite element simulation model. Specifically, the pipe type is associated with the model topology to determine whether the model includes a concrete counterweight layer, reinforcing bars, an outer steel pipe, and filling material; the pipe outer diameter, pipe wall thickness, concrete counterweight layer thickness, and cross-sectional void ratio are associated with the geometric model to determine the steel pipe's mid-surface dimensions, solid region thickness, double-layer pipe space, and the relative positions of various components; the explosive equivalent is associated with the explosive load model to determine the explosive region's mass, initial internal energy, or equivalent input intensity; the pipe pressure and transport medium type are associated with the material constitutive model and the pipe medium model to determine the initial state of the fluid inside the pipe and the initial pressure state of the steel pipe; the soil cover depth and ambient water depth are associated with the geometric model and boundary conditions, respectively, to determine the location of the buried pipe in the soil, the location of the soil's free surface, and the height of the fluid domain. Through this association, when a parameter changes, the associated model content changes synchronously, eliminating the need to manually rebuild the entire model.

[0042] In step S2, the geometric parameters are processed using an explicit dimension mapping method. For single-layer pipes and single-layer counterweight pipes, the pipe outer diameter... With pipe wall thickness The geometric dimensions of the steel pipe and the thickness of the concrete counterweight layer are jointly determined. The location of the outer boundary of the concrete counterweight layer is determined. For double-layer pipes and double-layer counterweight pipes, in addition to the outer layer geometry, the interlayer relationship between the inner and outer steel pipes needs to be adjusted according to the cross-sectional void ratio. The cross-sectional void ratio is still defined as: ;when When the change occurs, at least one of the outer diameter of the inner steel pipe or the inner diameter of the outer steel pipe changes, thereby altering the interlayer thickness, the volume of the filling material, and the overall local stiffness characteristics of the double-layer structure. This parameter serves as both a geometric parameter and a parameter for distinguishing subsequent operating conditions in this step.

[0043] In step S2, a unified scale is used to process the explosion load parameters. The explosive equivalent is expressed as TNT equivalent, and all contact and non-contact explosion conditions use TNT equivalent as the unified input scale. By adopting a unified equivalent scale, explosion scales from different sources and in different forms can be converted to the same parameter system, facilitating horizontal comparisons of different conditions within the same database. The explosive equivalent is correlated with the explosive material model, explosive region volume, and initial volume fraction defined in step S1, allowing the same material model to correspond to different explosion input conditions under different explosive scales.

[0044] In step S2, the processing of internal operating parameters includes two parts: pipe pressure and transport medium type. Pipe pressure is input as an initial load parameter into the pressure-bearing steel pipe and the pipe medium model to characterize the subsea pipeline's operating state before an explosion. The transport medium type is used to distinguish between natural gas, oil, and other transported media. When the transport medium type changes, different state equation models, density parameters, and initial state parameters are applied to the corresponding medium region. If the transport medium is natural gas, the pipe medium is treated as an adiabatic gas; if the transport medium is oil, a liquid state equation is used. This setting allows for a unified analysis of the differences in explosion-resistant response of the same structure under different transport conditions.

[0045] In step S2, the processing of environmental parameters includes two parts: cover depth and ambient water depth. Cover depth Used to control the vertical distance from the axis of the buried pipeline to the free surface of the soil. Ambient water depth. Used to control the size of the sea area and the relative spatial position of the explosive on the seabed surface. For suspended pipelines, the overburden depth is usually not used as a primary control parameter in adjusting the structural burial position; for buried pipelines, the overburden depth directly affects the distance the blast wave travels from the soil surface to the pipeline, and therefore should be treated as an independent variable in the parameter combination. Changes in ambient water depth will alter the length of the seawater propagation segment and the position of the water body boundary, and therefore are used to adjust the fluid domain height and the outer boundary setting position in non-contact blasting conditions.

[0046] The process of setting key parameters as variables does not involve arbitrarily combining all parameters. Instead, it first defines multiple value ranges for each parameter variable, and then generates multiple parameter combinations based on the combination relationships between different parameter variables. The principles for setting the value ranges include: first, the parameter values ​​should cover the actual structural range of the subsea pipeline being analyzed; second, the parameter values ​​should match the physical boundaries of the model established in step S1; and third, the parameter values ​​should facilitate the formation of comparable operating condition sequences. In practice, a discrete set of values ​​can be defined for each parameter. For example, the explosive equivalent can be set to multiple discrete levels, the pipeline outer diameter to multiple typical specifications, the pipe wall thickness to multiple thickness levels, the overburden depth to multiple burial depth levels, and the ambient water depth to multiple water depth levels. This results not in a single numerical value, but rather a candidate set of parameters.

[0047] When generating multiple parameter combinations, any one or a combination of the following three methods can be used. The first method is the full combination method, which involves performing a Cartesian product operation on multiple candidate parameter sets to form all parameter combinations. When the number of candidate values ​​for the i-th parameter is... The total number of operating conditions can then be expressed as: ; in, This represents the total number of operating conditions. The number of parameters involved in the combination. The first method represents the number of candidate values ​​for the i-th parameter. This method is suitable for establishing a comprehensive basic database. The second method is a hierarchical combination method, which fixes some parameters and expands the remaining parameters layer by layer to analyze the variation of a single engineering object on a specific parameter axis. The third method is a constraint combination method, which deletes parameter combinations that are obviously invalid or meaningless based on engineering constraints. For example, a non-zero concrete counterweight layer thickness is not assigned to a single-layer pipe case that does not contain a concrete counterweight layer, and a cross-sectional void ratio variable is not assigned to a case that is not a double-layer structure. By adopting the above combination rules, invalid cases can be avoided from entering the calculation set.

[0048] To ensure that each parameter combination is uniquely identifiable within the computational process, in step S2, each parameter combination is mapped to an independent computational case. Each independent computational case has a case number and corresponds to a unique parameter vector, a unique model input file, and a unique result storage path. The j-th case can be represented as: ; in, Let j be the parameter vector for the j-th working condition; superscript This represents the parameter value corresponding to the j-th working condition. In this way, each model called by the solver in subsequent step S3 corresponds to a set of defined parameter vectors, thus ensuring the traceability of calculation results and parameter sources.

[0049] In step S2, parameter activation rules need to be set for different pipe types. For single-layer pipes, the effective parameters include explosive equivalent, pipe type, pipe outer diameter, pipe wall thickness, internal pressure, transport medium type, and ambient water depth. For single-layer counterweight pipes, in addition to the above parameters, the concrete counterweight layer thickness is effective. For double-layer pipes, the cross-sectional void ratio is effective and used to control the geometric relationship between the inner and outer steel pipes. For double-layer counterweight pipes, both the concrete counterweight layer thickness and the cross-sectional void ratio are effective. For inapplicable parameters, the system can set them to null, default value, or invalid flag, but they will not participate in combination and solution. After adopting these parameter activation rules, different structural types are implemented under a unified parameter framework, and there will be no assignments that are incompatible with the structure.

[0050] Buried pipelines are assessed using a combination of overburden depth and explosive equivalent as evaluation parameters. This is because, when a buried pipeline is blasted, the effects on the pipeline depend not only on the explosive charge but also on the propagation distance from the free surface of the soil to the pipeline's location. To uniformly characterize the coupled effect of these two factors, this embodiment combines overburden depth and explosive equivalent to construct an evaluation parameter characterizing the blast's effects. Preferably, the evaluation parameter is expressed in the form of a proportional blast distance, i.e.: ; Where Z represents the proportional blast distance for buried pipelines. The depth of soil cover. The explosive equivalent is used. The physical meaning of the proportional blast distance is that the cube root of the explosive equivalent represents the characteristic scale of the explosion, and then expressed as a normalized ratio of the soil cover depth to this characteristic scale. Using this parameter, burial conditions under different explosive scales and soil cover depths can be compared at the same scale. A smaller proportional blast distance indicates a shallower burial depth for the same explosive scale, or a larger explosive scale for the same burial depth; a larger proportional blast distance indicates a larger burial depth for the same explosive scale, or a smaller explosive scale for the same burial depth. This parameter is constructed in step S2 and used in subsequent steps S4 and S5 for buried pipeline damage assessment and database classification.

[0051] In the specific generation of parameters for buried pipelines, two implementation methods can be adopted. In the first implementation method, multiple explosive equivalent levels are first set, and then multiple overburden depth levels are set under each explosive equivalent level, and the proportional blast distance is calculated accordingly. In the second implementation method, multiple target proportional blast distance intervals are first set, and then the corresponding overburden depth is calculated from a given explosive equivalent, or vice versa. The former method is suitable for database construction under known actual burial depth conditions, while the latter method is suitable for parameter selection around a specific explosive action scale. Both methods are completed in step S2 and do not affect the solution interface in the subsequent step S3.

[0052] During step S2, a consistency check of the parameter combination is also required. The consistency check includes at least the following: whether the pipe type matches the effective parameters; whether the cross-sectional void ratio is only taken in a double-layer structure; whether the concrete counterweight layer thickness is only taken in the counterweight pipe; whether the soil cover depth is consistent with the working condition type; whether the ambient water depth meets the fluid domain establishment conditions; whether the explosive equivalent matches the explosive area size setting; and whether the transport medium type is consistent with the material model of the medium inside the pipe. After the check is passed, a set of working conditions that can be directly used in step S3 is obtained.

[0053] In step S2, a parameter index table can also be established. The parameter index table records the correspondence between operating condition numbers and parameter values. Each row in the parameter index table corresponds to an independent calculation operating condition, and each column corresponds to a parameter variable. Subsequently, after the calculation results are output in step S3, the dynamic response data can be merged with the parameter index table using the operating condition number, thus forming a complete parameter-response-damage data entry. This processing method facilitates database construction and the generation of a damage limit capability quick reference table in subsequent step S5.

[0054] The parameter variable system and parameter combination mechanism established in step S2 enable each parameter to act on the model geometry, material and boundary conditions, forming a parameter set corresponding to the calculation conditions. At the same time, the buried pipeline conditions are uniformly characterized by combining evaluation parameters, thus providing standardized input for subsequent multi-condition simulation calculations.

[0055] S3. Based on the parametric finite element simulation model and multiple parameter combinations, perform multi-condition numerical simulation calculations to obtain the dynamic response data of the subsea pipeline during the entire process of explosive load. Preferably, in step S3, the multi-condition numerical simulation calculation steps include: Generate corresponding finite element input models for each combination of parameters; The explicit dynamic analysis solver is invoked to perform calculations on the finite element input model; The calculation process outputs the displacement response, stress response, strain response, and damage evolution of the subsea pipeline. The entire process of the explosion was tracked to obtain complete dynamic response data.

[0056] Specifically, in the finite element input model generation stage, for each set of parameter combinations in step S2 The model is instantiated separately. This process includes the following: writing the geometric parameters from the parameter vector into the model's geometric control field to generate steel pipes, concrete counterweight layers, reinforcing bars, and infill regions of corresponding dimensions; writing the material-related parameters from the parameter vector into the material card to update the constitutive parameters of the steel pipes, concrete, soil, fluid, and gas; writing the explosive load parameters into the explosive region definition to determine the explosive region volume, initial internal energy, and state equation parameters; and writing the boundary parameters into the fluid domain height, symmetry plane position, and non-reflective boundary position. Through the above processing, the template model is converted into a finite element input model for the current parameter combination.

[0057] In the finite element input model, the governing equations are solved using an explicit dynamic scheme. The governing equations for the motion of the solid domain can be expressed as: ; in, For the quality matrix, Let K be the damping matrix and K be the stiffness matrix. Let be the nodal displacement vector. For the node velocity vector, For the nodal acceleration vector, This is the external load vector, which mainly originates from the fluid pressure and contact force generated by the explosion. This equation is used to describe the dynamic response of subsea pipelines and seabed soil under the action of an explosion.

[0058] For the fluid domain, the mass conservation equation and the momentum conservation equation are used to describe the changes in fluid state. Their basic forms are: ; ; in, For fluid density, Let P be the fluid velocity vector and P be the fluid pressure. The above equation describes the propagation process of the explosion shock wave in seawater and soil. Through fluid-structure interaction, the fluid pressure is applied to the solid surface, thereby driving the pipe and soil to respond.

[0059] During time integration, the explicit dynamics method employs a central difference scheme for discretization. Nodal accelerations can be calculated from the difference between external and internal forces at the current moment, and then nodal velocities and displacements are obtained through time integration. The time step must satisfy stability conditions and is generally determined by the minimum element size and material wave velocity. By limiting the time step, the solution process remains numerically stable throughout the entire explosion response.

[0060] During the solver execution phase, the explicit dynamic analysis solver is invoked for each finite element input model. The following calculation process is sequentially completed: initializing material states, loading initial volume fractions, triggering explosive initiation, calculating the pressure evolution of detonation products, solving for shock wave propagation in the fluid domain, calculating pressure transmission at the fluid-structure interaction interface, updating nodal displacements and stress states in the solid domain, determining contact states and updating contact forces, and updating material damage variables. This process is repeated cyclically within each time step until the set termination condition is met. During the dynamic response data recording phase, key response quantities of the subsea pipeline are output throughout the entire process. The output includes: displacement response of pipeline nodal displacements over time; stress distribution and stress response of the steel pipe and concrete counterweight layer over time; equivalent strain and plastic strain of material elements and their strain response over time; and damage evolution of material damage variables over time. This data is achieved by setting output nodes, output elements, and output time intervals in the model. The output time interval is determined based on the explosion timescale, ensuring that both the rapid initial change phase and the later stable phase of the explosion can be recorded.

[0061] During the full-process response tracking phase, the entire explosion process is continuously recorded. This process includes explosive detonation, shock wave propagation, initial structural response, local structural deformation development, overall structural vibration, and the gradual stabilization of the response. By continuously outputting key response quantities during the solution process, a complete time history from the initial state to the final stable state can be obtained. This time history is used in subsequent step S4 to determine the final assessment time and extract the final damage state. During the contact and damage evolution processing, the solver uses a contact algorithm to determine the contact state between the seabed soil and the subsea pipeline and calculates the contact force. When the pipeline experiences local indentation or rebound, the contact state changes, affecting the local stress distribution. Simultaneously, the material model updates damage variables based on stress and strain states. When the stress or strain reaches the material failure condition, the corresponding element experiences damage or failure. For steel pipes, when the equivalent plastic strain exceeds the material's allowable range, it can be considered a tendency to fracture; for concrete counterweight layers, when the damage variable reaches a critical value, it manifests as local crushing or cracking. The above damage evolution information is recorded in the output data.

[0062] In setting the termination condition, this implementation does not use a fixed time as the sole termination condition, but rather determines the calculation termination time by combining the duration of the explosion and the structural response characteristics. Preferably, the calculation ends when the explosion shock wave has completed propagation, the structural vibration amplitude has significantly decreased, and the damage variables have stabilized. To ensure the integrity of the data throughout the entire process, a time window covering the entire explosion response is typically set in the calculation, and data is continuously recorded within this time window.

[0063] In terms of multi-condition calculation organization, all calculation conditions are submitted for solution sequentially according to condition number or parameter combination order. The calculation results of each condition are stored independently and mapped to the corresponding parameter vector. For conditions that are abnormal during the calculation process, such as contact penetration, severe element distortion, or numerical divergence, the calculation can be recalculated by adjusting the mesh generation, contact parameters, or time step to ensure that all conditions obtain valid response data.

[0064] By implementing step S3, the calculation conditions corresponding to each parameter combination can obtain complete dynamic response data of the entire explosion process, and ensure the consistency of the output data of different conditions in terms of time scale and data structure, thereby providing a unified data foundation for subsequent damage assessment.

[0065] S4. Based on dynamic response data, the final assessment time is determined when the response of the subsea pipeline structure tends to stabilize and the damage no longer develops, and the structural state corresponding to the final assessment time is taken as the final damage state; whether the steel pipe is ruptured or whether the transport medium is leaked is taken as the priority judgment basis, and when rupture or leakage occurs, it is judged as severe damage; when no rupture or leakage occurs, the depth of the indentation is used as the damage judgment basis to classify the damage level of the subsea pipeline. Preferably, in step S4, the step of classifying the damage level of the subsea pipeline includes: Analyze the dynamic response data; Determine the assessment point at which the subsea pipeline structure's response tends to stabilize and damage no longer progresses; The structural state at the time of assessment is taken as the final damage state.

[0066] Preferably, in step S4, the step of classifying the damage level of the subsea pipeline further includes: When a steel pipe ruptures or the transported medium leaks, the submarine pipeline is classified as severely damaged. When the steel pipe does not rupture and the transport medium does not leak, the minimum cross-sectional distance change at the location of the explosion on the submarine pipeline is taken as the indentation depth. The subsea pipeline was classified as slightly or moderately damaged based on the depth of the indentation.

[0067] Specifically, in step S4, time history analysis is first performed on the dynamic response data. The dynamic response data includes curves showing the change of nodal displacement over time, curves showing the change of stress and strain of key elements over time, and curves showing the change of material damage variables over time. By analyzing these curves, the time interval between the transition of the structural response from a rapid change phase to a slow change phase is identified. Preferably, the rate of change of the displacement response curve is used as the criterion; when the displacement increment within a consecutive number of time steps satisfies: ; At that time, it is considered that the overall displacement of the structure tends to stabilize. Among them, Let be the displacement value at time t. For time step, This is the threshold for determining displacement changes. This criterion is used to exclude the intense vibration phase in the initial stage of an explosion.

[0068] Simultaneously, material damage variables are monitored. When the increment of damage variables within a consecutive number of time steps satisfies: ; At that time, it was believed that the damage would no longer progress. Among them, Let be the damage variable at time t. To avoid corrections where the denominator is zero, The threshold for judging damage changes is set. The final assessment time is determined by simultaneously satisfying both displacement stability and damage stability conditions. This assessment time serves as a unified time benchmark for subsequent damage assessments.

[0069] After determining the final assessment time, the structural state corresponding to that time is extracted from the dynamic response data. The structural state includes: the stress distribution, plastic strain distribution, damage variable distribution, cross-sectional geometry, and the state of the medium inside the pipe. This state serves as the final damage state for subsequent classification.

[0070] In the rupture and leakage assessment phase, priority is given to determining whether the steel pipe has ruptured and whether the transported medium has leaked. The determination of steel pipe rupture can be based on equivalent plastic strain or damage variables. When the equivalent plastic strain of a certain unit of the steel pipe... satisfy: When this occurs, the unit is considered to have failed. This represents the material's fracture strain. If multiple units within a continuous region fail and form a through path, the steel pipe is considered to have ruptured. Leakage of the transport medium can be determined by checking whether there is communication between the medium region inside the pipe and the external fluid region. When a gas or liquid unit inside the pipe comes into contact with or penetrates the external fluid region, it is considered a medium leak. If either of these two determinations is met, the operating condition is classified as severe damage.

[0071] When no pipe rupture is detected and no leakage of the transported medium occurs, the indentation depth calculation stage begins. First, the damaged section corresponding to the location of the explosion is determined. This section is typically the cross-section at the location of maximum deformation along the axial direction of the pipe. Then, the minimum inner diameter or minimum span after deformation is extracted from this section. The indentation depth is defined as the difference between the initial characteristic dimension of the cross-section and the characteristic dimension of the cross-section after deformation, and its expression is: ; in, The depth of the depression These are the initial cross-sectional feature dimensions. This represents the minimum distance of the deformed cross-section in the direction of the explosion. For single-layer pipes and single-layer counterweight pipes, the characteristic dimension of the cross-section corresponds to the inner diameter of the steel pipe; for double-layer pipes and double-layer counterweight pipes, the characteristic dimension of the cross-section corresponds to the inner diameter of the inner steel pipe.

[0072] In the calculation of the indentation depth, this can be achieved in the following ways: select a radial direction on the cross-section consistent with the explosion direction, and extract the minimum distance between the innermost node and the opposite node in this direction; or obtain the minimum envelope size by fitting the cross-section nodes. The calculated... This serves as the basis for subsequent damage level classification. To achieve a unified comparison between different pipe diameters, a relative indentation depth index is introduced. The relative indentation depth is defined as the ratio of the indentation depth to the initial cross-sectional characteristic dimension: ; in, This represents the relative depth of the indentation. This dimensionless parameter allows for a unified judgment standard to be applied under different pipe diameter conditions.

[0073] During the damage level classification stage, the subsea pipeline is assessed for minor or moderate damage based on the relative depth of the indentation. In practice, a preset threshold is set. ,when: When: ; it is judged as a minor injury; when: At that time, it was determined to be a moderate injury. Among them, A preset judgment threshold is set, which is determined based on structural integrity requirements. In this embodiment, A value of 0.05 is used to distinguish between local deformation and significant structural deformation.

[0074] In the multi-condition data processing, the above steps are performed independently for each condition. The final output for each condition includes: whether a steel pipe rupture occurred, whether a leakage of the transport medium occurred, the depth of the dent, the relative depth of the dent, and the final damage level. The above output results are correlated with the condition number and parameter vector, and used for data collection and database construction in the subsequent step S5.

[0075] By implementing step S4, the dynamic response process is uniformly converted into the structural state at the final assessment time, and a unique damage level result is obtained according to the rules of prioritizing rupture or leakage and determining the depth of indentation, thereby achieving a consistent damage assessment method across different working conditions.

[0076] S5. Based on the relationship between the multiple sets of parameter combinations obtained in steps S2 to S4 and the corresponding damage levels, construct a database or a quick reference table of damage limit capabilities that associates key parameters with damage levels.

[0077] Preferably, in step S5, the step of constructing a database or a quick reference table for the correlation between key parameters and damage levels includes: Summarize the key parameters, dynamic response data, and damage levels corresponding to each calculation condition; Establish a mapping relationship between key parameters and damage levels; Store the mapping relationships in a database; A damage limit capability quick reference table is generated based on the database. The damage limit capability quick reference table is presented in the form of a parameter matrix and different damage levels are distinguished by different identifiers.

[0078] Specifically, in step S5, the data entry structure is first established. Each data entry corresponds to an independent calculation case, and its content includes at least the following fields: case number, parameter vector. Key parameter values, dynamic response characteristics, and damage level. The parameter vector is still represented as: ; The meanings of the symbols are consistent with those in step S2. Dynamic response characteristic quantities include, but are not limited to: maximum displacement, critical section stress, maximum equivalent strain, and final indentation depth. Relative depth of depression The damage level is determined by the discrete classification result identified in step S4, including whether a steel pipe rupture or a leakage of the transport medium occurred. Through the above field definitions, each data entry contains complete input parameters and corresponding output results. During data collection, the results of each calculation condition are written into a unified data structure according to the condition number or parameter combination order. This data structure can be in tabular, array, or database table format. The parameter field order is kept consistent during data writing to ensure a unified arrangement of data across different conditions, facilitating subsequent retrieval and processing.

[0079] When establishing the mapping relationship between key parameters and damage levels, the parameter vector Using damage level L as input and damage level L as output, construct a mapping function: ;in, This represents the mapping relationship calculated in steps S3 and S4, where L represents the damage level. This mapping relationship is not an analytical function, but rather a lookup relationship formed through discrete calculation results. For parameter combinations already existing in the database, the corresponding damage level can be directly obtained through the index; for parameter combinations that do not fully match, interpolation can be performed using neighboring parameter combinations, or the closest working condition result can be selected.

[0080] For buried pipelines, a proportional blasting distance parameter Z is preferably introduced into the mapping relationship, which adjusts the soil cover depth in the original parameter vector. Combining the explosive equivalent W with a single evaluation variable, the mapping relationship can be rewritten as follows: ; Where Z is the proportional blast distance, defined in step S2. By introducing this combined parameter, data on buried pipelines under different blast scales and burial depths can be organized at a unified scale.

[0081] During the database storage phase, the aforementioned data entries and mapping relationships are written to the storage medium. The database can adopt a relational structure, where each row represents a working condition record, and each column represents a parameter field or result field. Indexed fields are set in the database for fast querying, such as using the working condition number, pipeline type, or key parameters as indexes. Field names and field order are kept fixed during storage to ensure consistency in the database structure across different calculation batches.

[0082] During the damage limit capability quick reference table generation phase, a subset of key parameters is extracted from the database and a parameter matrix is ​​constructed. The rows and columns of the parameter matrix correspond to the two selected primary parameters, while the remaining parameters remain fixed or are grouped. For example, for buried pipelines, the proportional blast distance Z can be selected as the vertical axis, and the pipeline outer diameter as the horizontal axis. Alternatively, the explosive equivalent W can be used as the horizontal axis; for suspended pipes, the explosive equivalent W can be selected as the horizontal axis, and the pipe wall thickness can be used as the horizontal axis. or pipe outer diameter The vertical axis represents the matrix. Each cell in the matrix corresponds to a parameter combination, the value of which is the damage level for the corresponding working condition.

[0083] During the quick reference table population process, the damage level of the corresponding parameter combination is written into the matrix cell based on the existing data in the database. For cells without completely matching data, the following methods can be used: First, select the existing working condition result with the closest parameters for population; second, find neighboring points in the parameter space and determine the cell value using a weighted method; third, mark the cell as an uncovered area. The above methods are selected based on data integrity requirements.

[0084] To differentiate between different injury levels, the quick reference table uses different labeling methods for each level. Labeling methods can include different symbols, different numerical codes, or different colors. For example, mild injury is labeled "1", moderate injury is labeled "2", and severe injury is labeled "3"; or different colors can be used to distinguish different levels. The labeling method remains consistent throughout the quick reference table for easy identification.

[0085] By implementing step S5, the parameters and damage levels of each calculation condition are uniformly collected and a mapping relationship is established, and expressed in the form of a database or parameter matrix, thereby realizing the structured storage and query of the explosion-proof performance results.

[0086] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A parameterized evaluation method for the explosion-proof performance of subsea pipelines, characterized in that, Includes the following steps: S1. Establish a parameterized finite element simulation model for the explosion response of a subsea pipeline. The parameterized finite element simulation model is established by classifying the subsea pipeline into single-layer pipe, single-layer counterweight pipe, double-layer pipe and double-layer counterweight pipe according to the pipeline type, and into suspended pipeline and buried pipeline according to the working conditions. At the same time, the pipeline geometric model, material constitutive model, fluid-structure interaction boundary conditions and explosion load model are constructed in the model. S2. Set key parameters as variables, and generate multiple sets of parameter combinations based on the key parameters. The key parameters include explosive equivalent, pipe type, pipe outer diameter, pipe wall thickness, concrete counterweight layer thickness, cross-sectional void ratio, pipe pressure, transport medium type, soil cover depth and ambient water depth. S3. Based on the parametric finite element simulation model and the combination of multiple parameters, perform multi-condition numerical simulation calculations to obtain the dynamic response data of the subsea pipeline during the entire process of explosive load. S4. Based on the dynamic response data, when the response of the subsea pipeline structure tends to stabilize and the damage no longer develops, the final assessment time is determined, and the structural state corresponding to the final assessment time is taken as the final damage state. The primary criteria for determining damage to the subsea pipeline are whether the steel pipe is ruptured or whether the transport medium is leaking. When rupture or leakage occurs, the damage is classified as severe. When neither rupture nor leakage occurs, the depth of the indentation is used as the basis for damage assessment. S5. Based on the relationship between the multiple sets of parameter combinations obtained in steps S2 to S4 and the corresponding damage levels, construct a database or a quick reference table of damage limit capabilities that associates key parameters with damage levels.

2. The parameterized evaluation method for the explosion-proof performance of subsea pipelines according to claim 1, characterized in that, In step S1, the step of establishing a parameterized finite element simulation model of the subsea pipeline explosion response includes: Submarine pipelines are classified according to their type into single-layer pipes, single-layer counterweight pipes, double-layer pipes, and double-layer counterweight pipes. Submarine pipelines are classified according to their operating conditions into suspended pipelines and buried pipelines. Furthermore, corresponding parametric finite element simulation models were established for different pipeline types and operating conditions to form a unified model system covering multiple structural forms and multiple explosion conditions.

3. The parameterized evaluation method for the explosion-proof performance of subsea pipelines according to claim 1, characterized in that, In step S1, the step of establishing a parameterized finite element simulation model of the subsea pipeline explosion response further includes: Discrete modeling is performed on the steel pipe, concrete counterweight layer, reinforcing bars and filling material of the submarine pipeline. Among them, the steel pipe is simulated using shell elements, the concrete counterweight layer is simulated using solid elements, the reinforcing bars are simulated using beam elements, and the filling material is simulated using a foamed material model. Furthermore, the concrete counterweight layer is divided into multiple solid units along the thickness direction to improve the discrete resolution of thickness-direction stress and damage evolution under explosion.

4. The parameterized evaluation method for the explosion-proof performance of subsea pipelines according to claim 1, characterized in that, In step S1, the step of establishing a parameterized finite element simulation model of the subsea pipeline explosion response further includes: Establish fluid and solid domains, and establish fluid-structure interaction between the fluid and solid domains; Establish a contact relationship between the seabed soil and the subsea pipeline and set friction parameters; Symmetric boundary conditions are set on the symmetry plane of the fluid domain, non-reflective boundaries are set on the outer boundary of the fluid domain, and fixed constraints are set at the ends of the subsea pipeline. An explosion load model was established by filling the pipe with the initial volume fraction of explosives and gas. The positions of the explosives were set according to the suspended pipe and the buried pipe respectively, so as to form contact explosion and non-contact explosion loading modes.

5. The parameterized evaluation method for the explosion-proof performance of subsea pipelines according to claim 1, characterized in that, In step S2, the step of setting key parameters as variables includes: Explosive equivalent, pipe type, pipe outer diameter, pipe wall thickness, concrete counterweight layer thickness, cross-sectional void ratio, internal pressure, transport medium type, soil cover depth and ambient water depth are selected as a unified set of parameter variables. The parameter variables are then associated with the geometric model, material constitutive model, and boundary conditions in the parameterized finite element simulation model to achieve parameterized expression of the model.

6. The parameterized evaluation method for the explosion-proof performance of subsea pipelines according to claim 1, characterized in that, In step S2, the step of setting key parameters as variables further includes: Multiple value ranges can be set for each parameter variable; Generate multiple sets of parameter combinations based on the combination relationships between different parameter variables; Each set of parameters is mapped to an independent calculation condition; For buried pipelines, an assessment parameter is constructed by combining the soil cover depth and explosive equivalent to characterize the explosive effect, and then used for damage assessment of buried pipelines.

7. The parameterized evaluation method for the explosion-proof performance of subsea pipelines according to claim 1, characterized in that, In step S3, the multi-condition numerical simulation calculation step includes: Generate corresponding finite element input models for each combination of parameters; The explicit dynamic analysis solver is invoked to perform calculations on the finite element input model; The calculation process outputs the displacement response, stress response, strain response, and damage evolution of the subsea pipeline. The entire process of the explosion was tracked to obtain complete dynamic response data.

8. The parameterized evaluation method for the explosion-proof performance of subsea pipelines according to claim 1, characterized in that, In step S4, the step of classifying the damage level of the subsea pipeline includes: The dynamic response data is analyzed; Determine the assessment point at which the subsea pipeline structure's response tends to stabilize and damage no longer progresses; The structural state corresponding to the assessment time is taken as the final damage state.

9. The parameterized evaluation method for the explosion-proof performance of subsea pipelines according to claim 1, characterized in that, In step S4, the step of classifying the damage level of the subsea pipeline further includes: When a steel pipe ruptures or the transported medium leaks, the submarine pipeline is classified as severely damaged. When the steel pipe does not rupture and the transport medium does not leak, the minimum cross-sectional distance change at the location of the explosion on the submarine pipeline is taken as the indentation depth. The subsea pipeline is classified as slightly damaged or moderately damaged based on the depth of the indentation.

10. The parameterized evaluation method for the explosion-proof performance of subsea pipelines according to claim 1, characterized in that, In step S5, the step of constructing a database or a quick reference table for the correlation between key parameters and damage levels includes: Summarize the key parameters, dynamic response data, and damage levels corresponding to each calculation condition; Establish a mapping relationship between key parameters and damage levels; Store the mapping relationship in a database; A damage limit capability quick reference table is generated based on the database. The damage limit capability quick reference table is presented in the form of a parameter matrix and different damage levels are distinguished by different identifiers.

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