Method, device, equipment and storage medium for evaluating seismic performance of submarine suspended span pipelines

Abstract

The present invention provides a method, device, equipment and storage medium for evaluating the seismic performance of a submarine free-spanning pipeline. The method comprises: determining the velocity probability of different velocity intervals based on the ocean current data of the free-spanning pipeline to be evaluated; determining the annual fatigue damage caused by vortex-induced vibration in the transverse direction and the annual fatigue damage caused by vortex-induced vibration in the downstream direction based on a pre-constructed finite element model of the submarine free-spanning pipeline; determining the time-varying material properties of the free-spanning pipeline to be evaluated based on the annual fatigue damage caused by vortex-induced vibration in the transverse direction and the annual fatigue damage caused by vortex-induced vibration in the downstream direction, and updating the material properties in the finite element model to obtain a time-varying finite element model; performing nonlinear time-history analysis on the time-varying finite element model to obtain the structural response of the free-spanning pipeline to be evaluated at different life stages; determining the seismic vulnerability curve of the free-spanning pipeline based on the structural response at different life stages. The present invention can accurately evaluate the seismic performance of a submarine free-spanning pipeline.

Description

Technical Field

[0001] The present invention relates to the technical field of submarine pipeline structures, and in particular to a method, device, equipment and storage medium for evaluating the seismic performance of a submarine free-spanning pipeline. Background Art

[0002] Submarine pipelines have the advantages of continuity, speed, and large transmission capacity, and have become one of the lifelines of offshore oil and gas fields. Due to the harsh environmental conditions in which they are located, submarine pipelines are extremely susceptible to multiple factors such as ocean currents, navigation, fishery production, and earthquakes throughout their life cycle, and their safety issues require more attention.

[0003] Submarine pipelines are affected by the seabed, ocean currents, etc., and it is inevitable that they will have suspended spans. When the ocean current flows through the suspended span section of the submarine pipeline, a vortex will be formed in the wake area of ​​the structure, and the vortex will fall off alternately from the upper and lower sides of the pipeline at a certain frequency. In addition, in addition to the stable drag force of the ocean current, the suspended span section of the submarine pipeline is also subject to the pulsating drag force along the direction of the coastal current and the pulsating lift perpendicular to the direction of the ocean current caused by the vortex shedding, which causes the pipeline to vibrate in the in-line (IL) and cross-flow (CF) directions. This typical fluid-solid coupling phenomenon is called vortex-induced vibration. The cyclical reciprocating vortex-induced vibration in the in-line and cross-flow directions may cause fatigue damage to the suspended span section or accelerate the process of fatigue damage.

[0004] How to accurately evaluate the seismic performance of submarine suspended pipelines has become an urgent problem that needs to be solved. Summary of the invention

[0005] The embodiments of the present invention provide a method, device, equipment and storage medium for evaluating the seismic performance of a submarine free-spanning pipeline, so as to solve the problem that the seismic performance of a submarine free-spanning pipeline cannot be accurately evaluated at present.

[0006] In a first aspect, an embodiment of the present invention provides a method for evaluating the seismic performance of a submarine free-spanning pipeline, comprising:

[0007] Based on the ocean current data of the free-spanning pipeline to be evaluated, determine the flow velocity probability in different flow velocity intervals;

[0008] Based on the pre-built finite element model of the submarine free-spanning pipeline and the flow velocity probability, the annual fatigue damage caused by the vortex-induced vibration in the cross-flow direction and the annual fatigue damage caused by the vortex-induced vibration in the downstream direction are determined;

[0009] Determine the time-varying material properties of the free-span pipeline to be evaluated based on the annual fatigue damage caused by vortex-induced vibration in the transverse direction and the annual fatigue damage caused by vortex-induced vibration in the downstream direction;

[0010] Based on the time-varying material properties of the free-spanning pipeline to be evaluated, the material properties in the finite element model are updated to obtain a time-varying finite element model;

[0011] Perform nonlinear time history analysis on the time-varying finite element model to obtain the structural response of the free-span pipeline at different life stages to be evaluated;

[0012] Determine the seismic vulnerability curves of suspended span pipelines at different life stages based on the structural responses at different life stages

[0013] In a possible implementation, based on a pre-built finite element model of a submarine free-spanning pipeline and a flow velocity probability, the annual fatigue damage caused by vortex-induced vibration in the transverse direction and the annual fatigue damage caused by vortex-induced vibration in the downstream direction are determined, including:

[0014] Based on the pre-built finite element model of the submarine free-spanning pipeline, the stress range and cycle counting frequency caused by multi-modal cross-flow vortex-induced vibration at any position of the free-spanning pipeline to be evaluated are determined, and based on the flow velocity probability, the stress range and cycle counting frequency caused by multi-modal cross-flow vortex-induced vibration, the annual fatigue damage caused by the cross-flow vortex-induced vibration is determined;

[0015] Based on the finite element model of the submarine free-spanning pipeline, the stress range and cycle counting frequency caused by multi-modal downstream vortex-induced vibration at any position of the free-spanning pipeline to be evaluated are determined. Based on the flow velocity probability, the stress range and cycle counting frequency caused by multi-modal downstream vortex-induced vibration, the annual fatigue damage caused by the downstream vortex-induced vibration is determined.

[0016] In a possible implementation, based on a pre-constructed finite element model of a submarine free-spanning pipeline, the stress range and cycle count frequency caused by multi-modal cross-flow vortex-induced vibration at any position of the free-spanning pipeline to be evaluated are determined, including:

[0017] Based on the pre-built finite element model of the submarine free-spanning pipeline, the cross-flow natural frequency and the vibration mode corresponding to each natural frequency are extracted;

[0018] Based on the transverse flow natural frequency and the vibration mode corresponding to each natural frequency, determining the corresponding transverse flow amplitude under each vibration mode;

[0019] Based on the corresponding transverse flow amplitude under each vibration mode, determine the stress range caused by a single transverse flow vibration mode at any position of the free-span pipeline to be evaluated;

[0020] Based on the stress range caused by a single transverse flow vibration mode at any position of the free-spanning pipeline to be evaluated, the stress range and cycle counting frequency caused by multi-modal transverse flow vortex-induced vibration at any position of the free-spanning pipeline to be evaluated are determined.

[0021] In a possible implementation, based on the corresponding transverse flow amplitudes under each vibration mode, the stress range caused by a single transverse flow vibration mode at any position of the free-spanning pipeline to be evaluated is determined, including:

[0022] Based on the corresponding transverse flow amplitude under each vibration mode, the transverse flow vibration mode is divided into three levels;

[0023] Determine the stress range caused by a single transverse flow vibration mode at any position of the free-span pipeline to be evaluated under three levels.

[0024] In a possible implementation, based on a finite element model of a submarine free-spanning pipeline, the stress range and cycle count frequency caused by multi-modal downstream vortex-induced vibration at any position of the free-spanning pipeline to be evaluated are determined, including:

[0025] Based on the finite element model of the submarine free-span pipeline, the downstream natural frequency and the vibration mode corresponding to each natural frequency are extracted;

[0026] Based on the downstream natural frequency and the vibration mode corresponding to each natural frequency, determining the downstream amplitude corresponding to each vibration mode;

[0027] Based on the downstream amplitude corresponding to each vibration mode, determine the initial stress range caused by a single downstream vibration mode at any position of the free-spanning pipeline to be evaluated, and determine the stress range caused by the cross-flow direction to the downstream direction at any position of the free-spanning pipeline to be evaluated;

[0028] Based on the initial stress range caused by a single downstream vibration mode at any position of the free-spanning pipeline to be evaluated, and the stress range caused by the cross-flow direction to the downstream direction, the stress range and cycle counting frequency caused by multi-modal downstream vortex-induced vibration at any position of the free-spanning pipeline to be evaluated are determined.

[0029] In a possible implementation, determining the stress range caused by the cross-flow direction to the flow-forward direction at any position of the free-spanning pipeline to be evaluated includes:

[0030] Based on the magnitude of the initial stress range, the downstream vibration modes are classified as downstream contribution modes;

[0031] Based on the natural frequency ratio between adjacent modes of the downstream contribution mode, determine whether the mode pair competes, and calculate the adjacent mode competition reduction coefficient;

[0032] Based on the adjacent modal competition reduction coefficient and the initial stress range, the stress range caused by the pure downstream vibration mode at any position of the free-spanning pipeline to be evaluated is determined; as well as the stress range caused from the cross-flow direction to the downstream direction at any position of the free-spanning pipeline to be evaluated.

[0033] In a possible implementation, based on the ocean current data of the free-spanning pipeline to be evaluated, the flow velocity probabilities in different flow velocity intervals are determined, including:

[0034] Obtain the ocean current data of the free-spanning pipeline to be evaluated, and fit the probability distribution of the flow velocity in the deep-sea current where the free-spanning pipeline to be evaluated is located based on the Weibull distribution model and the ocean current data;

[0035] The probability distribution of flow velocity in the deep sea current where the free-spanning pipeline to be evaluated is discretized to obtain the flow velocity probability in different flow velocity intervals.

[0036] In a second aspect, an embodiment of the present invention provides a device for evaluating the seismic performance of a submarine free-spanning pipeline, comprising:

[0037] A flow velocity determination module, used to determine the flow velocity probability of different flow velocity intervals based on the ocean current data of the free-spanning pipeline to be evaluated;

[0038] The damage determination module is used to determine the annual fatigue damage caused by vortex-induced vibration in the cross-flow direction and the annual fatigue damage caused by vortex-induced vibration in the downstream direction based on the pre-built finite element model and flow velocity probability of the submarine free-span pipeline;

[0039] A property determination module, used to determine the time-varying material properties of the free-span pipeline to be evaluated based on the annual fatigue damage caused by the vortex-induced vibration in the cross-flow direction and the annual fatigue damage caused by the vortex-induced vibration in the downstream direction;

[0040] A model updating module is used to update the material properties in the finite element model based on the time-varying material properties of the free-spanning pipeline to be evaluated, so as to obtain a time-varying finite element model;

[0041] The analysis module is used to perform nonlinear time history analysis on the time-varying finite element model to obtain the probabilistic seismic demand model of the suspended span pipeline to be evaluated at different life stages;

[0042] The evaluation module is used to determine the seismic vulnerability curves of suspended spanning pipelines at different life stages based on the probabilistic seismic demand models at different life stages.

[0043] In a third aspect, an embodiment of the present invention provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the processor implements the steps of the method described in the first aspect or any possible implementation manner of the first aspect.

[0044] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method described in the first aspect or any possible implementation method of the first aspect are implemented.

[0045] The embodiment of the present invention provides a method for evaluating the seismic performance of a submarine free-spanning pipeline. Since different flow velocities will have different effects on the free-spanning pipeline, the flow velocity probability of different flow velocity intervals at the location of the free-spanning pipeline to be evaluated is first determined. Since the free-spanning pipeline will be subject to vortex-induced vibration in the transverse direction and the downstream direction, the annual fatigue damage caused by the vortex-induced vibration in the transverse direction and the annual fatigue damage caused by the vortex-induced vibration in the downstream direction are determined based on the pre-constructed finite element model of the submarine free-spanning pipeline and the flow velocity probability. Based on the annual fatigue damage caused by the vortex-induced vibration in the transverse direction and the annual fatigue damage caused by the vortex-induced vibration in the downstream direction, the time-varying material properties of the free-spanning pipeline to be evaluated are determined. After obtaining the time-varying material properties of the free-spanning pipeline to be evaluated, the material properties can be used to update the pre-constructed finite element model of the submarine free-spanning pipeline to obtain a time-varying finite element model. By performing nonlinear time-history analysis on the time-varying finite element model, the structural response of the free-spanning pipeline to be evaluated at different life stages can be obtained. Finally, based on the structural response at different life stages, the seismic vulnerability curve of the suspended spanning pipeline at different life stages can be determined, so that the seismic vulnerability curve can be used to evaluate the seismic performance. The present invention can determine the fatigue damage of the submarine suspended spanning pipeline at different service times according to the current velocity, and can also evaluate the seismic performance of the submarine suspended spanning pipeline at different life stages. This can overcome the previous neglect of the influence of the fatigue effect caused by vortex-induced vibration on the suspension relationship when evaluating the seismic performance, and thus improve the accuracy of the evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0047] Figure 1 It is a flow chart of the implementation of the method for evaluating the seismic performance of submarine free-spanning pipelines provided by an embodiment of the present invention;

[0048] Figure 2 is a schematic diagram of a cross-flow VIV response model provided by an embodiment of the present invention;

[0049] Figure 3 is a schematic diagram of a downstream VIV response model provided by an embodiment of the present invention;

[0050] Figure 4 is the probability density function of the ocean current velocity and the corresponding annual exceedance probability provided by the embodiment of the present invention;

[0051] Figure 5is a cross-flow VIV-year fatigue damage curve provided by an embodiment of the present invention;

[0052] Figure 6 is a downstream VIV-year fatigue damage curve provided by an embodiment of the present invention;

[0053] Figure 7 is the total VIV annual fatigue damage curve provided by the embodiment of the present invention;

[0054] Figure 8 It is a vulnerability curve of a free-spanning pipeline corresponding to a slight damage state at different life stages provided by an embodiment of the present invention;

[0055] Fig. 9 is a vulnerability curve of a free-spanning pipeline corresponding to a moderate damage state at different life stages provided by an embodiment of the present invention;

[0056] Fig.10 It is a vulnerability curve of a free-spanning pipeline corresponding to a severe damage state at different life stages provided by an embodiment of the present invention;

[0057] Fig.11 It is a structural schematic diagram of a submarine free-spanning pipeline seismic performance evaluation device provided by an embodiment of the present invention;

[0058] Fig.12 is a schematic diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0059] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0060] In order to make the purpose, technical solutions and advantages of the present invention more clear, specific embodiments will be described below in conjunction with the accompanying drawings.

[0061] As introduced in the background technology, submarine free-span pipelines undertake the important task of marine oil and gas transportation, which greatly promotes the development of the national economy. However, during its entire life cycle, submarine free-span pipeline structures will inevitably be attacked by earthquakes and the harsh environment of the deep sea, such as chloride ion corrosion, wave and current impact, and fishing boat collision, etc., and even devastating damage will occur under the coupling of earthquakes and vortices, which will have an inestimable impact on the marine environment.

[0062] During the long service life of the submarine free-span pipeline, under certain conditions, when the ocean current flows through the pipeline free-span section, a vortex will be formed in the wake area of ​​the structure, and the vortex will fall off alternately from the upper and lower sides of the pipeline at a certain frequency. In this process, in addition to the stable drag force of the ocean current, the pipeline free-span section will also be subject to the pulsating drag force along the direction of the ocean current caused by the vortex shedding and the pulsating lift perpendicular to the direction of the ocean current, which will cause the pipeline to vibrate in the in-line (IL) and cross-flow (CF) directions. This typical fluid-solid coupling phenomenon is called vortex-induced vibration (VIV). The reciprocating vortex-induced vibration of the submarine free-span pipeline in the in-line and cross-flow directions may cause fatigue damage to the structure or accelerate the process of other fatigue damage.

[0063] Therefore, it is very important to evaluate the seismic performance of submarine free-spanning pipelines to ensure their safety and functionality.

[0064] In order to solve the problems of the prior art, the embodiments of the present invention provide a method, device, equipment and storage medium for evaluating the seismic performance of a submarine free-spanning pipeline. The following first introduces the method for evaluating the seismic performance of a submarine free-spanning pipeline provided by the embodiments of the present invention.

[0065] See also Figure 1 , which shows a flowchart of the implementation of the method for evaluating the seismic performance of a submarine free-spanning pipeline provided by an embodiment of the present invention, and is described in detail as follows:

[0066] S110: Determine flow velocity probabilities in different flow velocity intervals based on ocean current data of the free-spanning pipeline to be evaluated.

[0067] In some embodiments, first, the ocean current data of the free-spanning pipeline to be evaluated is obtained, and based on the Weibull distribution model and the ocean current data, the probability distribution of the flow velocity in the deep sea current where the free-spanning pipeline to be evaluated is fitted.

[0068] Next, the probability distribution of the flow velocity in the deep sea current where the free-spanning pipeline to be evaluated is discretized to obtain the flow velocity probability in different flow velocity intervals.

[0069] In this embodiment, firstly, based on the free-spanning pipeline to be evaluated, the ocean current data in which it is located is counted, and the three-parameter Weibull distribution model is selected to fit the collected ocean current data around the submarine free-spanning pipeline structure to obtain the probability distribution of the flow velocity in the deep sea current where the free-spanning pipeline to be evaluated is located. The ocean current data may be ocean current velocity.

[0070] Next, the ocean current velocity Discretization is performed to statistically collect the two extreme values ​​of the ocean current velocity. and , the flow rate range ( ) is discretized into Q intervals, then q The probability of flow rate in the interval The determination process is:

[0071]

[0072] In the formula, For the q The representative flow velocity of an interval is taken as the median value of the flow velocity in the interval. is the probability distribution of flow velocity in the deep sea current where the free-spanning pipeline to be evaluated is located.

[0073] S120. Based on the pre-constructed finite element model and flow velocity probability of the submarine free-spanning pipeline, determine the annual fatigue damage caused by the vortex-induced vibration in the cross-flow direction and the annual fatigue damage caused by the vortex-induced vibration in the downstream direction.

[0074] In some embodiments, based on a pre-constructed finite element model of a submarine free-spanning pipeline, the stress range and cycle count frequency caused by multi-modal cross-flow vortex-induced vibration at any position of the free-spanning pipeline to be evaluated can be determined, and based on the flow velocity probability, the stress range and cycle count frequency caused by multi-modal cross-flow vortex-induced vibration, the annual fatigue damage caused by the cross-flow vortex-induced vibration can be determined.

[0075] It is also possible to determine the stress range and cycle counting frequency caused by multi-modal downstream vortex-induced vibration at any position of the free-spanning pipeline to be evaluated based on the finite element model of the submarine free-spanning pipeline, and to determine the annual fatigue damage caused by the downstream vortex-induced vibration based on the flow velocity probability, the stress range and cycle counting frequency caused by multi-modal downstream vortex-induced vibration.

[0076] In this embodiment, the method for determining the stress range and cycle count frequency caused by multi-modal cross-flow vortex-induced vibration at any position of the free-span pipeline to be evaluated is as follows:

[0077] S1210. Based on the pre-constructed finite element model of the submarine free-spanning pipeline, extract the cross-flow natural frequency and the vibration mode corresponding to each natural frequency.

[0078] The finite element model of the submarine free-span pipeline was established using ABAQUS finite element software to extract the cross-flow natural frequency ( =1,2,…,n*) and the vibration mode corresponding to each natural frequency.

[0079] S1211. Based on the transverse flow natural frequency and the vibration mode corresponding to each natural frequency, determine the transverse flow amplitude corresponding to each vibration mode.

[0080] Based on current speed , transverse natural frequency ( =1,2,…,n*) and the vibration mode corresponding to each natural frequency, calculate the flow rate ratio Reduced velocity V R , and the Keulegan-Carpenter number KC.

[0081] , , ;

[0082] in, is the wave velocity, is the effective frequency of the wave load, D is the outer diameter of the pipeline,

[0083] When the flow rate ratio hour:

[0084] ;

[0085] When the flow rate ratio hour:

[0086] ;

[0087] in, It is the frequency ratio of adjacent vibration modes in the cross-flow direction of the suspended pipeline.

[0088] ;

[0089]

[0090]

[0091] in, and are the correction factors considering the distance from the seabed and the relationship between the pipeline and the trench, respectively. is the safety factor of the starting speed of the vortex-induced vibration in the cross-flow direction; Based on the above formula, the following can be drawn: Figure 2 The cross-flow VIV response model shown in the figure, that is, the cross-flow response amplitude in the cross-flow VIV response model ( ) and the reduced velocity Through Figure 2 The cross-flow amplitude corresponding to each vibration mode can be calculated The value of .

[0092] S1212. Determine the stress range caused by a single transverse flow vibration mode at any position of the free-spanning pipeline to be evaluated based on the corresponding transverse flow amplitude under each vibration mode.

[0093] In order to highlight the contribution of different vibration modes to the fatigue damage of suspended span pipelines, the transverse amplitude The transverse flow vibration modes are divided into three levels based on the size of the transverse flow, namely, the transverse flow dominant mode, the general mode and the invalid mode. The transverse flow dominant mode corresponds to the largest transverse flow amplitude. , which is expressed as follows:

[0094] ;

[0095] Calculate the span of the pipeline at any position Stress range caused by a single transverse flow vibration mode:

[0096] ;

[0097] In the formula, for The unit stress amplitude caused by the transverse modal deformation at the position; is the stress amplitude safety factor, The reduction factor is taken into account for the damping effect.

[0098] Determine the spanning pipeline to be evaluated at any location The stress range caused by a single transverse flow vibration mode at:

[0099] .

[0100] S1213. Based on the stress range caused by a single transverse flow vibration mode at any position of the free-spanning pipeline to be evaluated, determine the stress range and cycle count frequency caused by multi-modal transverse flow vortex-induced vibration at any position of the free-spanning pipeline to be evaluated.

[0101] ;

[0102] ;

[0103] ;

[0104] In the formula, the mass ratio , still water added mass coefficient , It is the dynamic water added mass coefficient of vortex-induced vibration in the cross-flow direction of the pipeline.

[0105] After determining the stress range and cycle counting frequency caused by multi-modal cross-flow vortex-induced vibration at any position of the free-span pipeline to be evaluated, the annual fatigue damage caused by cross-flow vortex-induced vibration at any position of the free-span section of the pipeline under various current conditions can be determined. The calculation process is as follows:

[0106]

[0107] ;

[0108] In the formula, is the flow rate The annual fatigue damage in the transverse direction under the action of is the flow rate The probability of SCF is the stress concentration factor, and m are the characteristic fatigue strength constant and fatigue index of SN curve, is the unit of stress.

[0109] After determining the annual fatigue damage caused by the vortex-induced vibration in the transverse direction, it is also necessary to determine the annual fatigue damage caused by the vortex-induced vibration in the downstream direction. The specific determination process is as follows:

[0110] S1220. Based on the finite element model of the submarine free-spanning pipeline, extract the downstream natural frequency and the vibration mode corresponding to each natural frequency.

[0111] Extracting the downstream natural frequency from the finite element model of the submarine free-span pipeline The vibration mode corresponding to each natural frequency.

[0112] S1221. Based on the downstream natural frequency and the vibration mode corresponding to each natural frequency, determine the downstream amplitude corresponding to each vibration mode.

[0113]

[0114]

[0115]

[0116]

[0117] In the formula, To design stable parameters, is the safety factor of the stability parameter, is a stable parameter, is the safety factor of the downstream vortex-induced vibration starting speed, is the initial reduced velocity, is the reduced velocity at the endpoint.

[0118] Based on the above calculations, we constructed Figure 3 The downstream VIV response model shown in the figure reflects the downstream response amplitude in the downstream VIV response model. With reduced speed relationship, according to Figure 3 The downstream amplitude corresponding to each vibration mode can be determined .

[0119] S1222. Based on the downstream amplitude corresponding to each vibration mode, determine the initial stress range caused by a single downstream vibration mode at any position of the free-spanning pipeline to be evaluated, and determine the stress range caused by the cross-flow direction to the downstream direction at any position of the free-spanning pipeline to be evaluated.

[0120] Suspended pipeline at any position The initial stress range caused by the single downstream vibration mode at is:

[0121] ;

[0122] ;

[0123] In the formula, for The unit stress amplitude caused by the downstream modal deformation at position, is the reduction factor of the ocean current velocity under wave-dominated sea conditions, is the stress amplitude safety factor.

[0124] Initial stress range The downstream vibration modes are divided into three levels based on the size of:

[0125] ;

[0126] In the present invention, the invalid modes in the downstream direction can be ignored, and the dominant modes in the downstream direction and the general modes in the downstream direction are uniformly classified as the downstream contribution modes and renumbered, so as to obtain the corresponding downstream natural frequency sequence: , 1,2,…, and the initial stress range sequence . Determine whether adjacent modes compete. If the natural frequency ratio of two adjacent downstream contribution modes is less than 2, the mode pair will compete; otherwise, the mode pair is independent of each other. Calculate the modal competition reduction coefficient according to the specific situation of the adjacent modes :

[0127] 1,2,…, ;

[0128] ;

[0129]

[0130] ;

[0131] Determine the spanning pipeline to be evaluated at any location The stress range caused by the pure downstream vibration mode at is:

[0132] ;

[0133] The downstream mode whose natural frequency is closest to twice the natural frequency of the dominant mode in the transverse direction is selected as the candidate mode of the transverse-to-stream VIV:

[0134] ;

[0135] Calculate the pipeline span to be evaluated at any location The stress range caused by VIV from the cross-flow direction to the downstream direction is:

[0136] ;

[0137] for The unit stress amplitude caused by the transverse modal deformation at position, is the maximum transverse amplitude corresponding to the transverse dominant mode, is the stress amplitude safety factor; The reduction factor is taken into account for the damping effect.

[0138] Calculate the pipeline span to be evaluated at any location The stress range caused by a single downstream vibration mode is:

[0139] ;

[0140] S1223. Determine the stress range and cycle count frequency caused by multi-modal downstream vortex-induced vibration at any position of the free-spanning pipeline to be evaluated based on the initial stress range caused by a single downstream vibration mode at any position of the free-spanning pipeline to be evaluated, and the stress range caused by the cross-flow direction to the downstream direction.

[0141] Calculate the pipeline span to be evaluated at any location The stress range and cycle count frequency caused by multi-modal forward VIV are:

[0142] ;

[0143] ;

[0144] .

[0145] After determining the stress range and cycle count frequency caused by multi-modal downstream vortex-induced vibration at any position of the free-span pipeline to be evaluated, the annual fatigue damage caused by the downstream vortex-induced vibration can be determined. The determination process is as follows:

[0146]

[0147]

[0148] in, is the flow rate Annual fatigue damage in the downstream direction under the action of is the flow rate The probability of occurrence; is the stress concentration factor; and are the characteristic fatigue strength constant and fatigue index of SN curve respectively.

[0149] The total VIV fatigue damage caused by the free-span pipeline to be evaluated during the entire fatigue cycle can be obtained by linearly superimposing the VIV fatigue damage in the cross-flow direction and the VIV fatigue damage in the downstream direction.

[0150] S130. Determine the time-varying material properties of the free-span pipeline to be evaluated based on the annual fatigue damage caused by the vortex-induced vibration in the transverse direction and the annual fatigue damage caused by the vortex-induced vibration in the downstream direction.

[0151] Annual fatigue damage caused by vortex-induced vibration in the transverse direction and annual fatigue damage caused by downstream vortex-induced vibration , the time-varying material properties of the free-spanning pipeline to be evaluated are determined as follows:

[0152] ;

[0153] ;

[0154] in, , To consider the time-varying material properties of VIV fatigue damage; is the material coefficient, The possible value is 0.227.

[0155] S140. Based on the time-varying material properties of the free-spanning pipeline to be evaluated, the material properties in the finite element model are updated to obtain a time-varying finite element model.

[0156] The time-varying material properties of the free-span pipeline to be evaluated obtained in S130 are used to update the material properties in the finite element model in S120, so that a time-varying finite element model of different life stages considering the VIV fatigue effect can be established.

[0157] S150. Perform nonlinear time history analysis on the time-varying finite element model to obtain the structural response of the free-span pipeline to be evaluated at different life stages.

[0158] The maximum strain of the spanning pipeline to be evaluated As an indicator of structural seismic demand, the damage state of the structure is defined.

[0159] Select a certain number of natural earthquake waves, generally 10-20, and input them into the time-varying finite element model. Perform nonlinear time history analysis on the established time-varying finite element model to obtain the corresponding structural response. The structural response here includes the seismic motion IM, the time-varying structural seismic demand under the action of the seismic motion and structural seismic capacity C The median value of (T).

[0160] S160. Determine the seismic vulnerability curves of suspended span pipelines at different life stages based on the structural responses at different life stages.

[0161] Substituting the obtained structural response into the following formula, we can obtain the seismic vulnerability curve of suspended span pipelines at different life stages considering VIV fatigue effect:

[0162] ;

[0163] ;

[0164] in, express The probability that a structure will achieve a certain performance level under action; is the standard normal cumulative distribution function; and Structural seismic demand D and structural seismic capacity C The median value of represents the logarithmic standard deviation of the structural demand, which is used to reflect the uncertainty of ground motion and the uncertainty of structural modeling; IM Indicates earthquake shaking; N is the number of samples in the linear regression analysis; No. Time-varying seismic demands of structures subjected to ground motions.

[0165] After obtaining the seismic vulnerability curve of the free-spanning pipeline at different life stages considering the VIV fatigue effect, the full-life seismic performance evaluation of the submarine free-spanning pipeline structure can be carried out based on the curve.

[0166] In order to facilitate understanding of the method for evaluating the seismic performance of a submarine free-spanning pipeline provided by the present invention, an example is given below for explanation:

[0167] In this embodiment, a free-span pipeline structure in the Bohai Bay area is used for illustration. The free-span pipeline is a lattice steel pipe structure with an outer diameter of 600 mm and a wall thickness of 18 mm, and is made of API X65 grade steel.

[0168] S210. Collect the ocean current velocity data in the Bohai Bay area for the past 30 years, and use Weibull parameters to characterize the distribution of ocean current velocity near the pipeline, as shown in Table 1:

[0169] Table 1 Weibull distribution parameters of ocean current velocity

[0170]

[0171] Figure 4 The probability density function of the Weibull distribution of the above current velocity and the corresponding annual exceedance probability are given. Figure 4 The probability density function in is used to calculate the velocity probability of different current velocity intervals, as shown in Table 2:

[0172] Table 2 Probability of occurrence of different current velocity intervals (unit: m / s)

[0173]

[0174] It should be noted that the numerical value in brackets in the flow rate interval represents the representative flow rate of the interval.

[0175] S220. Determine the annual fatigue damage caused by the vortex-induced vibration in the transverse direction and the annual fatigue damage caused by the vortex-induced vibration in the downstream direction.

[0176] Combining the random variable method and the LSH method, 120 uncertain finite element models of the structural example were established through ABAQUS, and the first 8 natural frequencies and corresponding vibration modes and unit amplitude modal stresses were extracted, as shown in Table 3, where the natural frequency is the average of the 120 uncertain finite element models. The 1st, 3rd, 5th and 7th vibration modes of the submarine free-span pipeline structure are in the transverse direction, and the 2nd, 4th, 6th and 8th vibration modes are in the downstream direction.

[0177] Table 3 The first 8 natural frequencies and corresponding vibration modes

[0178]

[0179] The 1st, 3rd, 5th and 7th order vibration modes mentioned above are renumbered as the 1st, 2nd, 3rd and 4th order vibration modes in the transverse direction. According to the vibration modes and unit amplitude modal stress of the transverse direction vibration modes, for the current velocity in the range of 0.25 m / s-1.45 m / s, the 1st, 2nd and 3rd order vibration modes in the transverse direction are contributing vibration modes. Using the calculation method of transverse direction VIV year fatigue damage provided above, the transverse direction VIV year fatigue damage caused by all current conditions can be calculated, and the transverse direction VIV fatigue damage caused by the submarine free-spanning pipeline in the entire fatigue cycle can be obtained by linear accumulation. Figure 5 The envelope curves and average curves of VIV-year fatigue damage in the transverse direction at different axial positions of 120 uncertain finite element models of structural examples are given.

[0180] The above 2nd, 4th, 6th and 8th order vibration modes are renumbered as the 1st, 2nd, 3rd and 4th order vibration modes in the downstream direction. For the current velocity in the range of 0.25 m / s-1.45 m / s, the 1st, 2nd and 3rd order vibration modes in the downstream direction are contributing vibration modes, among which, for the velocity in the range of 0.25 m / s-1.15 m / s, the 1st order vibration mode is the dominant mode, and for the velocity in the range of 1.25 m / s-1.45 m / s, the 2nd order vibration mode is the dominant mode. The VIV fatigue damage value of the submarine free-spanning pipeline structure at different axial positions in the downstream direction under different current velocities can be calculated. Figure 6 The envelope curves and average curves of VIV-year fatigue damage in the downstream direction at different axial positions of 120 uncertain finite element models of structural examples are given.

[0181] The total VIV fatigue damage caused by the submarine free-spanning pipeline structure during the entire fatigue cycle can be obtained by linearly superimposing the VIV fatigue damage in the cross-flow direction and the VIV fatigue damage in the downstream direction, as shown in Figure 7 shown.

[0182] S230: Based on the time-varying material properties of the free-spanning pipeline to be evaluated, the material properties in the finite element model are updated.

[0183] By calculating the time-varying material properties considering VIV fatigue damage, we can obtain the time-varying material model at different positions of the structural example.

[0184] ;

[0185] ;

[0186] By updating the material parameters in the uncertain finite element model accordingly, 120 time-varying finite element models of the example structure at different life stages can be established. The design service life of the structure example is 40 years. Therefore, at 10-year intervals, the time-varying models of the submarine free-spanning pipeline with life stages of 0 years (no fatigue damage), 10 years, 20 years, 30 years and 40 years are established.

[0187] S240. Determine the seismic vulnerability curves of suspended span pipelines at different life stages.

[0188] A total of 120 earthquake time histories were generated using the random variable method, and the maximum strain was selected as the damage state indicator of the structure. Three damage states of submarine free-span pipelines were defined: slight damage, moderate damage, and severe damage, as shown in Table 4.

[0189] Table 4 Damage status and structural capacity of submarine free-span pipelines

[0190]

[0191] The generated seismic time history is used to perform nonlinear dynamic time history analysis on different time-varying finite element models to obtain the corresponding structural responses. The probabilistic seismic demand model of suspended span pipeline structures at different life stages can be obtained through linear regression analysis.

[0192] Then, based on the following formula

[0193] ;

[0194] The seismic vulnerability curves of suspended span pipelines at different life stages corresponding to different limit states can be calculated, such as Figure 8-10 shown.

[0195] from Figure 8-10 It can be seen that as the VIV action of the ocean current progresses, the probability of the suspended span pipeline structure reaching different limit states increases with the fatigue time. Taking PGA = 0.6g as an example, the probability of the suspended span pipeline without fatigue damage reaching LS1, LS2 and LS3 is 93.59%, 66.47% and 4.43% respectively, and the probability of the suspended span pipeline with a fatigue time of 40 years reaching the three limit states is 99.58%, 94.47% and 33.31%, which is 5.99%, 28.00% and 28.88% higher than that of the suspended span pipeline without fatigue damage. Table 5 shows the mean PGA of seismic vulnerability of the suspended span pipeline structure at different life stages when it reaches the three limit states.

[0196] Table 5 Mean PGA values ​​of seismic vulnerability of structures at different life stages

[0197]

[0198] As shown in the table, affected by VIV fatigue damage, the mean PGA of the suspended span pipeline structure under the action of submarine spatial earthquake motion when it reaches the three limit states gradually decreases with the increase of time. Compared with the suspended span pipeline model without fatigue damage, the PGA of the suspended span pipeline model with a fatigue time of 40 years when it reaches LS1, LS2 and LS3 are reduced by 44.91%, 45.17% and 45.99% respectively. The above results show that the seismic vulnerability of the submarine suspended span pipeline structure gradually increases with the increase of fatigue time, that is, the accumulation of VIV fatigue damage will gradually reduce the seismic performance of the structure. From the perspective of structural safety, the seismic design and seismic analysis of the submarine suspended span pipeline structure must consider the influence of VIV fatigue damage.

[0199] The evaluation method provided by the present invention first determines the flow velocity probability of different flow velocity intervals at the location of the free-spanning pipeline to be evaluated, because different flow velocities will have different effects on the free-spanning pipeline. Since the free-spanning pipeline will be subject to vortex-induced vibration in the transverse and downstream directions, based on the pre-constructed finite element model of the submarine free-spanning pipeline and the flow velocity probability, the annual fatigue damage caused by the vortex-induced vibration in the transverse direction and the annual fatigue damage caused by the vortex-induced vibration in the downstream direction are determined. And based on the annual fatigue damage caused by the vortex-induced vibration in the transverse direction and the annual fatigue damage caused by the vortex-induced vibration in the downstream direction, the time-varying material properties of the free-spanning pipeline to be evaluated are determined. After obtaining the time-varying material properties of the free-spanning pipeline to be evaluated, the material properties can be used to update the pre-constructed finite element model of the submarine free-spanning pipeline to obtain a time-varying finite element model. And by performing nonlinear time-history analysis on the time-varying finite element model, the structural response of the free-spanning pipeline to be evaluated at different life stages can be obtained. Finally, based on the structural response at different life stages, the seismic vulnerability curve of the suspended spanning pipeline at different life stages can be determined, so that the seismic vulnerability curve can be used to evaluate the seismic performance. The present invention can determine the fatigue damage of the submarine suspended spanning pipeline at different service times according to the current velocity, and can also evaluate the seismic performance of the submarine suspended spanning pipeline at different life stages. This can overcome the previous neglect of the influence of the fatigue effect caused by vortex-induced vibration on the suspension relationship when evaluating the seismic performance, and thus improve the accuracy of the evaluation.

[0200] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0201] Based on the method for evaluating the seismic performance of a submarine free-spanning pipeline provided in the above embodiment, the present invention also provides a specific implementation of a device for evaluating the seismic performance of a submarine free-spanning pipeline applied to the method for evaluating the seismic performance of a submarine free-spanning pipeline. Please refer to the following embodiment.

[0202] like Fig.11 As shown, a device 1100 for evaluating the seismic performance of a submarine free-spanning pipeline is provided, the device comprising:

[0203] A flow velocity determination module 1110, for determining flow velocity probabilities in different flow velocity intervals based on the ocean current data of the free-spanning pipeline to be evaluated;

[0204] The damage determination module 1120 is used to determine the annual fatigue damage caused by the vortex-induced vibration in the cross-flow direction and the annual fatigue damage caused by the vortex-induced vibration in the downstream direction based on the pre-constructed finite element model of the submarine free-spanning pipeline;

[0205] The characteristic determination module 1130 is used to determine the time-varying material characteristics of the free-span pipeline to be evaluated based on the annual fatigue damage caused by the vortex-induced vibration in the cross-flow direction and the annual fatigue damage caused by the vortex-induced vibration in the downstream direction;

[0206] A model updating module 1140 is used to update the material properties in the finite element model based on the time-varying material properties of the free-spanning pipeline to be evaluated, so as to obtain a time-varying finite element model;

[0207] The analysis module 1150 is used to perform nonlinear time history analysis on the time-varying finite element model to obtain a probabilistic seismic demand model of the suspended span pipeline to be evaluated at different life stages;

[0208] The evaluation module 1160 is used to determine the seismic vulnerability curves of the suspended spanning pipelines at different life stages based on the probabilistic seismic demand models at different life stages.

[0209] Fig.12 Schematic diagram of an electronic device provided by an embodiment of the present invention. Fig.12 As shown, the electronic device 12 of this embodiment includes: a processor 120, a memory 121, and a computer program 122 stored in the memory 121 and executable on the processor 120. When the processor 120 executes the computer program 122, the steps in the above-mentioned embodiments of the method for evaluating the seismic performance of a submarine free-spanning pipeline are implemented, such as Figure 1 Alternatively, when the processor 120 executes the computer program 122, the functions of each module in the above-mentioned device embodiments are realized, for example, Fig.11 Functions of modules 1110 to 1160 are shown.

[0210] Exemplarily, the computer program 122 may be divided into one or more modules, which are stored in the memory 121 and executed by the processor 120 to implement the present invention. The one or more modules may be a series of computer program instruction segments that can implement specific functions, and the instruction segments are used to describe the execution process of the computer program 122 in the electronic device 12. For example, the computer program 122 may be divided into Fig.11 Modules 1110 to 1160 are shown.

[0211] The electronic device 12 may include, but is not limited to, a processor 120 and a memory 121. Those skilled in the art will appreciate that Fig.12 It is only an example of the electronic device 12 and does not constitute a limitation of the electronic device 12. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device may also include input and output devices, network access devices, buses, etc.

[0212] The processor 120 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0213] The memory 121 may be an internal storage unit of the electronic device 12, such as a hard disk or memory of the electronic device 12. The memory 121 may also be an external storage device of the electronic device 12, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device 12. Further, the memory 121 may also include both an internal storage unit of the electronic device 12 and an external storage device. The memory 121 is used to store the computer program and other programs and data required by the electronic device. The memory 121 may also be used to temporarily store data that has been output or is to be output.

[0214] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0215] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0216] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0217] In the embodiments provided by the present invention, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0218] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0219] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0220] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, the steps of the above-mentioned embodiments of the method for evaluating the seismic performance of submarine suspended spanning pipelines can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device that can carry the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium.

[0221] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A method for evaluating the seismic performance of a submarine free-spanning pipeline, characterized in that: include: Based on the ocean current data of the free-spanning pipeline to be evaluated, determine the flow velocity probability in different flow velocity intervals; Based on a pre-constructed finite element model of a submarine free-spanning pipeline, the transverse flow natural frequency and the vibration mode corresponding to each natural frequency are extracted; based on the transverse flow natural frequency and the vibration mode corresponding to each natural frequency, the corresponding transverse flow amplitude under each vibration mode is determined; based on the transverse flow amplitude under each vibration mode, the stress range caused by a single transverse flow vibration mode at any position of the free-spanning pipeline to be evaluated is determined; based on the stress range caused by a single transverse flow vibration mode at any position of the free-spanning pipeline to be evaluated, the stress range and cycle counting frequency caused by multi-modal transverse flow vortex-induced vibration at any position of the free-spanning pipeline to be evaluated are determined; and based on the flow velocity probability, the stress range caused by multi-modal transverse flow vortex-induced vibration and the cycle counting frequency, the annual fatigue damage caused by the transverse flow vortex-induced vibration is determined; Based on the finite element model of the submarine free-spanning pipeline, the downstream natural frequency and the vibration mode corresponding to each natural frequency are extracted; based on the downstream natural frequency and the vibration mode corresponding to each natural frequency, the downstream amplitude corresponding to each vibration mode is determined; based on the downstream amplitude corresponding to each vibration mode, the initial stress range caused by a single downstream vibration mode at any position of the free-spanning pipeline to be evaluated is determined; and based on the size of the initial stress range, the downstream vibration mode is classified as a downstream contribution mode; based on the natural frequency ratio between adjacent modes of the downstream contribution mode, it is determined whether a mode pair competes, and the adjacent mode competition reduction coefficient is calculated; based on the adjacent mode competition reduction coefficient, the adjacent mode competition reduction coefficient is calculated. The stress range caused by the pure downstream vibration mode at any position of the free-spanning pipeline to be evaluated is determined based on the reduction coefficient and the initial stress range; and the stress range caused by the cross-flow direction to the downstream direction at any position of the free-spanning pipeline to be evaluated; based on the initial stress range caused by the single downstream vibration mode at any position of the free-spanning pipeline to be evaluated, and the stress range caused by the cross-flow direction to the downstream direction, the stress range and cycle counting frequency caused by the multi-modal downstream vortex-induced vibration at any position of the free-spanning pipeline to be evaluated are determined; and based on the flow velocity probability, the stress range caused by the multi-modal downstream vortex-induced vibration and the cycle counting frequency, the annual fatigue damage caused by the downstream vortex-induced vibration is determined; Determining the time-varying material properties of the free-span pipeline to be evaluated based on the annual fatigue damage caused by the cross-flow vortex-induced vibration and the annual fatigue damage caused by the downstream vortex-induced vibration; Based on the time-varying material properties of the free-spanning pipeline to be evaluated, the material properties in the finite element model are updated to obtain a time-varying finite element model; Performing nonlinear time-history analysis on the time-varying finite element model to obtain structural responses of the free-span pipeline to be evaluated at different life stages; Based on the structural responses at different life stages, seismic vulnerability curves of the free-spanning pipelines at different life stages are determined.

2. The method for evaluating the seismic performance of a submarine free-spanning pipeline according to claim 1, characterized in that: The step of determining the stress range caused by a single transverse flow vibration mode at any position of the free-spanning pipeline to be evaluated based on the corresponding transverse flow amplitudes under each vibration mode includes: Based on the corresponding transverse flow amplitudes under each vibration mode, the transverse flow vibration modes are divided into three levels; The stress range caused by a single transverse flow vibration mode at any position of the free-span pipeline to be evaluated under three levels is determined.

3. The method for evaluating the seismic performance of a submarine free-spanning pipeline according to claim 1 or 2, characterized in that: The method of determining the flow velocity probabilities in different flow velocity intervals based on the ocean current data of the free-spanning pipeline to be evaluated comprises: Acquire the ocean current data of the free-spanning pipeline to be evaluated, and obtain the probability distribution of the flow velocity in the deep sea current where the free-spanning pipeline to be evaluated is located by fitting based on the Weibull distribution model and the ocean current data; The probability distribution of the flow velocity in the deep sea current where the free-spanning pipeline to be evaluated is discretized to obtain the flow velocity probabilities in different flow velocity intervals.

4. A device for evaluating the seismic performance of submarine free-span pipelines, characterized in that: include: A flow velocity determination module, used to determine the flow velocity probability of different flow velocity intervals based on the ocean current data of the free-spanning pipeline to be evaluated; A damage determination module is used to extract the transverse flow natural frequency and the vibration mode corresponding to each natural frequency based on a pre-constructed finite element model of a submarine free-spanning pipeline; determine the corresponding transverse flow amplitude under each vibration mode based on the transverse flow natural frequency and the vibration mode corresponding to each natural frequency; determine the stress range caused by a single transverse flow vibration mode at any position of the free-spanning pipeline to be evaluated based on the transverse flow amplitude under each vibration mode; determine the stress range and cycle counting frequency caused by multi-modal transverse flow vortex-induced vibration at any position of the free-spanning pipeline to be evaluated based on the stress range caused by a single transverse flow vibration mode at any position of the free-spanning pipeline to be evaluated; and determine the annual fatigue damage caused by the transverse flow vortex-induced vibration based on the flow velocity probability, the stress range caused by the multi-modal transverse flow vortex-induced vibration, and the cycle counting frequency; Based on the finite element model of the submarine free-spanning pipeline, the downstream natural frequency and the vibration mode corresponding to each natural frequency are extracted; based on the downstream natural frequency and the vibration mode corresponding to each natural frequency, the downstream amplitude corresponding to each vibration mode is determined; based on the downstream amplitude corresponding to each vibration mode, the initial stress range caused by a single downstream vibration mode at any position of the free-spanning pipeline to be evaluated is determined; and based on the size of the initial stress range, the downstream vibration mode is classified as a downstream contribution mode; based on the natural frequency ratio between adjacent modes of the downstream contribution mode, it is determined whether a mode pair competes, and the adjacent mode competition reduction coefficient is calculated; based on the adjacent mode competition Based on the reduction coefficient and the initial stress range, determine the stress range caused by the pure downstream vibration mode at any position of the free-spanning pipeline to be evaluated; and the stress range caused by the cross-flow direction to the downstream direction at any position of the free-spanning pipeline to be evaluated; based on the initial stress range caused by the single downstream vibration mode at any position of the free-spanning pipeline to be evaluated, and the stress range caused by the cross-flow direction to the downstream direction, determine the stress range and cycle counting frequency caused by the multi-modal downstream vortex-induced vibration at any position of the free-spanning pipeline to be evaluated; and based on the flow velocity probability, the stress range caused by the multi-modal downstream vortex-induced vibration and the cycle counting frequency, determine the annual fatigue damage caused by the downstream vortex-induced vibration; A property determination module, used to determine the time-varying material property of the free-span pipeline to be evaluated based on the annual fatigue damage caused by the vortex-induced vibration in the cross-flow direction and the annual fatigue damage caused by the vortex-induced vibration in the downstream direction; A model updating module, used to update the material properties in the finite element model based on the time-varying material properties of the free-spanning pipeline to be evaluated, so as to obtain a time-varying finite element model; An analysis module, used for performing nonlinear time-history analysis on the time-varying finite element model to obtain structural responses of the free-span pipeline to be evaluated at different life stages; The evaluation module is used to determine the seismic vulnerability curves of the suspended spanning pipeline at different life stages based on the structural responses at the different life stages.

5. An electronic device, characterized in that: The method comprises a memory and a processor, wherein the memory is used to store a computer program, and the processor is used to call and run the computer program stored in the memory to execute the method according to any one of claims 1 to 3.

6. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 3 are implemented.

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