Method for constructing longitudinal evolution model of in-service ballastless seamless turnout considering resistance update

Abstract

The application provides a method for constructing a longitudinal evolution model of an in-service ballastless seamless turnout considering resistance updating, and belongs to the technical field of rail transit. The method comprises the following steps: step 1, parameterized modeling of the seamless turnout; step 2, construction of boundary conditions and equilibrium equations; step 3, resistance curve drift analysis and equivalent processing; step 4, dynamic updating of resistance parameters; and step 5, nonlinear solving and model construction. The application can extend the modeling theory of the ballastless seamless turnout from the design reference state to the service state. Compared with the traditional method, the application also supports dynamic updating of resistance parameters in multi-load step iteration calculation, and can more accurately simulate the longitudinal creeping behavior of the ballastless seamless turnout. The application can be combined with digital twin technology to provide theoretical support for the service state reconstruction, model correction and safety evaluation of the seamless turnout.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of rail transit technology, in particular to a method for constructing a longitudinal evolution model of a seamless turnout in service considering resistance updating. BACKGROUND

[0002] Seamless lines are widely used because they eliminate welded joints and have strong driving stability. As one of the key technologies, seamless turnouts have a large number of track pieces, different line shapes and constraint conditions, complex multi-track force transmission mechanisms and nonlinear displacement coordination relationships. In operation practice, under the coupling of temperature, vehicles and other factors, seamless turnouts continuously experience stretching and contraction. A large amount of unevenly distributed longitudinal force is accumulated in the internal part of the turnout, accompanied by accumulation of residual deformation of the rail and degradation of the line resistance, which easily causes rail creep exceeding the standard and conversion jamming. Especially in high-altitude unmanned area railways, the high-cold large daily temperature difference, long and steep slopes, mixed passenger and freight running, frequent braking / starting and other extreme environments and complex conditions further increase the technical difficulty of seamless turnouts in construction and maintenance. Therefore, it has important engineering value to combine the actual service state of the seamless turnout for quantitative characterization and mechanism analysis to construct an intelligent maintenance decision system for the whole life cycle.

[0003] Previous studies on seamless turnouts have mainly focused on the analysis of typical working conditions under the design reference state, and there is no modeling theory for seamless turnouts in the service stage. In addition, in the simulation calculation under cyclic loading, there is a lack of effective method for dynamic correction and updating of resistance parameters in subsequent calculations. This will limit the applicability of existing safety evaluation models, and further lead to the difficulty of insufficient scientific basis for reliability evaluation and state maintenance decision of seamless turnouts in the service stage.

[0004] In the prior art, Yang Rongshan proposed a seamless line longitudinal action monitoring method based on digital twinning technology. The specific process mainly includes laying sensors in special sections such as high-pier large-span bridges, bridge-tunnel transition sections and seamless turnouts, collecting temperature and displacement data of the seamless line. A corresponding finite element model of the seamless line is established to calculate the temperature, displacement and longitudinal additional force of the structure. A CNN-Bi-GRU-GWO neural network model with adaptive hyperparameters is used to establish the mapping relationship between the physical database and the virtual database. By judging whether the error value of the virtual data output by the mapping model and the actual physical data exceeds the threshold value, the line resistance, locking rail temperature and other parameters of the mapping model are dynamically optimized and corrected. Finally, the construction of a digital twinning virtual body consistent with the physical state of the special section of the seamless line is realized, and data interaction with the field is supported.

[0005] But the above seamless line modeling theory is also based on the establishment of design reference state. Even if the digital twin technology is used to optimize the calculation parameters, the related simulation still assumes the initial state of the seamless line (i.e. zero deformation and zero residual stress) as the hypothetical condition, and fails to fully consider the influence of factors such as the longitudinal residual stress and residual deformation of the rail in the service process, thereby limiting the mapping accuracy of the digital twin model. In addition, relying only on intelligent algorithms and pure data-driven methods to search for suitable parameter values makes it difficult to reveal the evolution mechanism of the service state of the seamless line from the physical and mechanical mechanism level. SUMMARY

[0006] The application provides a method for constructing a longitudinal evolution model of a seamless turnout in service considering resistance updating, which can extend the modeling theory of a seamless turnout from a design reference state to a service state. Based on the historical data of rail displacement-fastener resistance, the drift amount of the resistance curve and the loading and unloading state of the node are solved. Through the equivalent treatment of the rail stress state, the fastener constitutive relationship and the load path, the longitudinal service state of the seamless turnout in service is accurately restored by combining the finite element method. In addition, compared with the traditional method, the application also supports dynamic updating of the resistance parameters in the multi-load step iteration calculation, which can more accurately simulate the longitudinal creeping behavior of the seamless turnout. The application can be combined with digital twin technology to provide theoretical support for the reconstruction of the service state of the seamless turnout, model correction, safety evaluation, etc.

[0007] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0008] The method for constructing a longitudinal evolution model of a seamless turnout in service considering resistance updating comprises:

[0009] Step 1: parameterized modeling of the seamless turnout;

[0010] A seamless turnout model containing rails, fasteners, limiters and spacer irons is constructed by using the finite element method and parameterized modeling, rail nodes and sleeper nodes are defined, and variable cross-section rail elements are defined in combination with the rail node and key feature section information, and the direction angle, length and element stiffness of the variable cross-section rail elements are determined;

[0011] Step 2: construction of boundary conditions and equilibrium equations;

[0012] Only the longitudinal degrees of freedom of the rail are considered, the extended sections are set at the front and rear ends of the seamless turnout to eliminate the boundary effect, and the boundary conditions are set according to the actual constraints, the rail node displacement equilibrium equation is established according to the longitudinal resistance-displacement relationship slope function of the fasteners, limiters and spacer irons, and the corresponding relationship between the rail element longitudinal stress and the node displacement difference is established according to Hooke's law;

[0013] Step 3: resistance curve drift analysis and equivalent treatment;

[0014] Obtain the longitudinal resistance-displacement time series data of the seamless turnout in service and discretize it according to load steps, determine the origin drift of the fastener resistance curve and the constitutive relation under each load step, and perform equivalent treatment on the target load step from three aspects of the stress state of the rail, the constitutive relation of the fastener and the load path.

[0015] Step 4: Dynamic updating of resistance parameters;

[0016] Based on the relevant data of the initial resistance curve, a logic matrix for judging the state of the rail node is constructed, and according to the actual degradation degree of the resistance parameters, the origin drift of the resistance curve, the loading and unloading path and the constitutive relation are corrected to realize the dynamic updating of the resistance parameters.

[0017] Step 5: Nonlinear solving and model building;

[0018] Combine the parameterized information of the rail node, element, etc. of the ballastless seamless turnout determined in step 1, the displacement balance equation established in step 2, the origin drift of the fastener resistance curve of the first LSQ load step and the equivalent process (including rail stress state equivalent, fastener constitutive relation equivalent, load path equivalent) obtained in step 3, and the change amount of the origin drift of the fastener resistance curve and the loading and unloading path derived in step 4 to build a nonlinear force balance equation, perform multi-load step analysis, use the Newton-Raphson method for nonlinear iterative calculation and judge the result according to the convergence criterion to complete the model building.

[0019] In the specification, when defining the rail node in step 1, each rail is divided into nodes along the longitudinal direction at a preset interval, and the preset interval is determined according to the sleeper arrangement interval, the installation position of the longitudinal force transmission component and the position of the variable cross-section of the rail, and the sleeper node is only set at the position of the turnout sleeper with fasteners.

[0020] In the specification, the length of the rail extension section in step 2 is determined according to the total length of the seamless turnout and the influence range of the boundary effect, and the type of the rail of the extension section is consistent with the type of the rail of the seamless turnout connected thereto.

[0021] In the specification, when establishing the displacement balance equation in step 2, the measured data of the longitudinal resistance of the fastener, the position limiter and the spacer iron under different displacements are first obtained, and then the longitudinal resistance-displacement relationship slope function is obtained through piecewise linear fitting.

[0022] In the specification, the concentrated force in step 2 includes the longitudinal force transmitted by the position limiter and the spacer iron, which needs to be judged according to whether there is a longitudinal concentrated force in the middle of the rail element to establish the force and deformation relationship of the rail element respectively.

[0023] In the specification, when determining the origin drift in step 3, the last intersection point of the resistance-displacement time series curve of the fastener from the initial load step to the current load step with the x-axis is the origin drift.

[0024] In the specification, step 3 realizes the rapid compensation of the service period resistance curve drift effect by applying a forced displacement to the sleeper node.

[0025] In the specification, the equivalent load path in step 3 refers to the moving track of the rail node displacement following the slope of the fastener resistance curve, and the displacement changes from the original point of the fastener resistance curve to the target displacement. Specifically, it is divided into two cases: one is a single loading path, and the other is a composite path composed of a loading path and an unloading path.

[0026] In the specification, when constructing the state discrimination logic matrix in step 4, the value 0 in the matrix represents the loading state, and the value 1 represents the unloading state. The state discrimination depends on whether the two consecutive displacements in the load path solved in step 3 are equal. If they are equal, it is determined to be loading, otherwise it is determined to be unloading.

[0027] In the specification, step 5 multi-load step analysis needs to apply equivalent load to reconstruct the service state of the seamless turnout, and then apply the subsequent load conditions to be analyzed. In each load step iteration calculation, force and displacement convergence criteria need to be judged.

[0028] In summary, the present application has at least the following beneficial effects:

[0029] The present application realizes a multi-dimensional technical breakthrough through the complete technical scheme of "parameterized modeling - boundary condition construction - drift analysis and equivalent treatment - resistance parameter dynamic update - nonlinear solving", and the core effects are as follows:

[0030] 1. The modeling theory is extended to cover the entire service period: The present application breaks through the limitation of existing technology based on design benchmark state modeling, and extends the modeling theory of ballastless seamless turnout to the actual service state, fully considers the cumulative effect of rail residual stress and residual deformation in the service process, and solves the problem of inconsistency between the simulation model and the actual service state.

[0031] 2. The reconstructed model has high precision: Through the resistance curve drift theory and three equivalent treatments (rail stress, fastener constitutive, load path), combined with the longitudinal resistance-displacement time sequence data on site, the service state of the turnout is restored with high precision. Experimental verification shows that the rail longitudinal displacement error is controlled within 2 mm, and the maximum longitudinal force error is only 0.02kN, which shows that the method proposed by the present application can accurately reconstruct the longitudinal evolution state of the ballastless seamless turnout in the service stage.

[0032] 3. Dynamic updating of drag parameters to ensure long-term stability: An innovative dynamic updating algorithm for drag parameters is proposed. In multi-load step iterative calculations, the drift of the drag curve origin, loading / unloading paths, and constitutive relations are corrected in real time to ensure the accuracy of drag parameters under long-term cyclic loading, avoiding model calculation deviations caused by drag distortion. After 25 days of daily rail temperature cycling calculations with an amplitude of 55℃ (-45℃ to 10℃), the drag curve remained smooth and continuous before and after the update, confirming that the proposed drag parameter updating method can guarantee the stability and reliability of subsequent calculations.

[0033] 4. Effective Integration of Physical Data: A physical model of the ballastless seamless turnout is constructed based on Hooke's Law and the resistance constitutive relation, and its service status is calibrated and equivalently restored by combining resistance-displacement time series data. This modeling method not only makes up for the lack of mechanistic support in pure data analysis, but also solves the defect that traditional physical models cannot reflect the actual service status, providing a scientific basis for turnout service status reconstruction and fault prediction.

[0034] 5. Outstanding engineering application value: The model has the potential to be deeply integrated with digital twin technology, supporting the construction of an intelligent maintenance decision-making system for the entire life cycle of seamless turnouts. It is especially suitable for long-term safety assessment of ballastless seamless turnouts in extreme environments such as high altitude, high cold and large temperature difference, reducing potential disease risks and reducing operation and maintenance costs. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the method for constructing a longitudinal evolution model of in-service ballastless seamless turnout that takes into account resistance updates, as involved in this invention.

[0037] Figure 2 This is a schematic diagram illustrating the technical route of the method for constructing a longitudinal evolution model of in-service ballastless seamless turnout that considers resistance updates, as involved in this invention.

[0038] Figure 3 This is a schematic diagram of the accuracy verification process involved in this invention.

[0039] Figure 4 This is a schematic diagram showing the comparison of longitudinal displacement results of the rail during the accuracy verification process involved in this invention.

[0040] Figure 5 This is a schematic diagram showing the comparison of longitudinal force results of the rail during the accuracy verification process involved in this invention.

[0041] Figure 6 The schematic diagram of resistance-displacement time history curve comparison of the first fastener of the heel of the frog involved in the application before and after the resistance updating algorithm is adopted. DETAILED DESCRIPTION

[0042] In the following, only certain exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the embodiments of the application. Therefore, the drawings and the description are considered to be exemplary in nature rather than limiting.

[0043] The following disclosure provides many different embodiments, or examples, for implementing different structures of the embodiments of the application. For the purpose of simplifying the disclosure of the embodiments of the application, the components and settings of specific examples are described in the following. Of course, they are only examples, and the purpose is not to limit the embodiments of the application. In addition, the embodiments of the application can refer to the same reference numerals and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, which does not indicate the relationship between the various embodiments and / or settings discussed.

[0044] The embodiments of the application are described in detail below with reference to the accompanying drawings.

[0045] As shown in Figure 1 and Figure 2 The present embodiment provides a method for constructing a longitudinal evolution model of a service seamless turnout considering resistance updating, comprising the following steps:

[0046] Step 1: Parametric modeling of seamless turnout

[0047] 1) A finite element method and a parametric modeling method are used to construct a seamless turnout model, which includes rails, fasteners, limiters and interval irons, wherein the rails include straight main rails, curved frog-rail-side stock wing rails, long center rails, short center rails, heel frog rails, straight frog-rail-straight stock wing rails and curved main rails;

[0048] 2) Define rail nodes and sleeper nodes respectively, the rail nodes are represented by an identifier containing two subscripts, the first subscript is used to distinguish the type of rail, and the second subscript is used to represent the node serial number of the corresponding type of rail along the longitudinal direction from left to right, the rail nodes include rail nodes located at the support of sleepers, rail nodes for characterizing variable cross-section characteristics, and rail nodes corresponding to the installation position of longitudinal force transmission components, the sleeper nodes only involve sleepers that need to be set with fasteners;

[0049] 3) combining the information of the rail node and the rail key feature section, defining the variable cross-section rail element in sequence, and determining the direction angle, length and element stiffness of each variable cross-section rail element;

[0050] Step 2: Construction of boundary conditions and equilibrium equations

[0051] 1) Only the longitudinal degree of freedom of the rail is considered in the modeling process;

[0052] 2) The boundary conditions are set according to the actual constraint state of different rails: the two ends of the basic rail are constrained by fixed end constraints, the center rail is only constrained by a fixed end constraint at the end, and the two ends of the rail are not constrained by a fixed end constraint and are only constrained by the rail fastener system;

[0053] 3) According to the longitudinal resistance-displacement relationship slope function of the fastener, spacer and spacer, the displacement equilibrium equation of the rail node is established respectively;

[0054] 4) Two cases are distinguished according to whether there is a concentrated force in the middle of the rail element, and the corresponding relationship between the longitudinal force state of the rail element and the longitudinal displacement difference between the two end nodes of the rail element is established by Hooke's law;

[0055] Step 3: Resistance curve drift analysis and equivalent treatment

[0056] 1) Obtain the longitudinal resistance-displacement time series data of the seamless turnout in the actual service process, divide the load history of the seamless turnout into M+1 load steps, and discretely process the longitudinal resistance-displacement time series data according to the load steps to obtain the discrete longitudinal resistance-displacement data;

[0057] 2) Based on the discrete longitudinal resistance-displacement data, the origin drift amount of the fastener resistance curve and the resistance-displacement curve constitutive relationship under each load step are determined, and the origin drift amount is the displacement value corresponding to the last intersection point of the resistance-displacement curve and the x-axis;

[0058] 3) For the target load step corresponding to the service state to be restored, equivalent treatment is performed from three aspects of rail stress state, fastener constitutive relationship and load path: among them, the rail stress state equivalent needs to ensure that the displacement of the rail node changes from the initial displacement to the displacement corresponding to the target load step; the fastener constitutive relationship equivalent needs to apply a forced displacement to the sleeper node to compensate for the drift effect of the resistance curve under cyclic loading; the load path equivalent needs to first judge the loading and unloading state of the rail node, and then solve the equivalent load path of the rail node moving along the specified path;

[0059] Step 4: Dynamic updating of resistance parameters

[0060] 1) Construct a logic matrix for judging the loading and unloading state of the rail node based on the original point drift and the loading and unloading path obtained from the initial resistance curve, wherein the logic matrix is used for distinguishing the loading and unloading state of the rail node;

[0061] 2) According to the actual degradation degree of the resistance parameter, the original point drift of the resistance curve, the loading and unloading path, and the constitutive relationship of the resistance-displacement curve are corrected to realize the dynamic updating of the resistance parameter;

[0062] Step 5: Nonlinear solving and model construction

[0063] 1) Combine the parameterized information of the rail node, element, etc. of the ballastless seamless turnout model determined in step 1, the displacement balance equation established in step 2, the original point drift of the fastener resistance curve at the first LSQ load step and the equivalent process (including rail stress state equivalence, fastener constitutive relationship equivalence, load path equivalence) obtained in step 3, and the change of the original point drift and the loading and unloading path of the fastener resistance curve derived in step 4 to construct a nonlinear force balance equation;

[0064] 2) Perform multi-load step analysis on the nonlinear force balance equation: first apply the equivalent load step to restore the longitudinal service state of the seamless turnout, and then apply the subsequent load conditions to be analyzed;

[0065] 3) Perform nonlinear iterative calculation by using the Newton-Raphson method, judge the force state of the rail in the iteration process and consider the influence of geometric nonlinearity, update the nonlinear equation set at the same time, and finally judge the convergence of the calculation results according to the force and displacement convergence criterion to complete the construction and solving of the longitudinal evolution model of the in-service ballastless seamless turnout.

[0066] In some embodiments, in step 1, when defining the rail node and the sleeper node respectively, the definition of the rail node needs to first determine the longitudinal length of each type of rail, and then divide the nodes in sequence along the longitudinal direction according to the preset interval, wherein the preset interval is determined according to the arrangement interval of the sleepers, the installation position of the longitudinal force transmission component, and the position of the variable cross-section of the rail, and the sleeper node is only set at the position of the turnout sleeper with fasteners.

[0067] In some embodiments, in step 2, when setting the extension section at the front end and the rear end of the seamless turnout respectively, the length of the extension section is determined according to the total length of the seamless turnout and the influence range of the boundary effect, and the rail type of the extension section is consistent with the rail type of the seamless turnout connected thereto.

[0068] In some embodiments, in step 2, when establishing the displacement balance equation of the rail node, the longitudinal resistance measurement data of the fasteners, limiters, and spacers under different displacements need to be obtained first, and then the longitudinal resistance-displacement relationship slope function is obtained through piecewise linear fitting.

[0069] In some embodiments, in step 2, when distinguishing the two cases of whether there is a concentrated force in the middle of the rail unit, the concentrated force includes the longitudinal force transmitted by the limit stop and the spacer, and the presence of a longitudinal concentrated force in the middle of the rail unit is used as the basis for distinguishing, and the force and deformation relationship of the rail unit is established respectively.

[0070] In some embodiments, in step 3, when determining the origin drift amount of the fastener resistance curve at each load step, the last intersection point of the resistance-displacement time curve of the fastener from the initial load step to the current load step and the x-axis is the origin drift amount.

[0071] In some embodiments, in step 3, when performing equivalent processing from three aspects of rail stress state, fastener constitutive relationship and load path, the equivalent of the fastener constitutive relationship needs to be compensated quickly by applying a forced displacement to the sleeper node to realize the drift effect of the service period resistance curve.

[0072] In some embodiments, in step 3, when solving the equivalent load path of the rail node moving along the specified path, the specified path is the moving track of the rail node following the slope of the resistance curve, which changes from the resistance curve drift amount to the target displacement. Specifically, it is divided into two cases: the first is a single loading path; the second is a composite path composed of a loading path and an unloading path.

[0073] In some embodiments, in step 4, when constructing the state discrimination logic matrix of the rail node, the value 0 in the state discrimination logic matrix represents the loading state, and the value 1 represents the unloading state. The discrimination of the state depends on whether the two consecutive displacement amounts in the equivalent load path solved in step 3 are equal. If they are equal, it is determined to be loading, otherwise it is determined to be unloading.

[0074] In some embodiments, in step 5, when performing multi-load step analysis on the nonlinear force balance equation, the multi-load step analysis needs to apply an equivalent load to reconstruct the service state of the seamless turnout, and then apply the subsequent load conditions to be analyzed, and in each load step iteration calculation, the force and displacement convergence criteria need to be judged.

[0075] The technical concept of the present application is as follows:

[0076] Step 1: Parametric modeling of seamless turnout

[0077] 1) Use finite element method and parametric modeling to build a ballastless seamless turnout model, which includes rails, fasteners, limit stops, spacers and other components.

[0078] 2) The rails include straight basic rails, curved nose rail-guide rail-side stock wing rail, long center rail, short center rail, cross heel rail, straight nose rail-guide rail-straight stock wing rail, and curved basic rail. First, define the nodes of the rail layer and the sleeper layer, respectively , The superscript is used to define the attribute, where r represents the rail and s represents the frog tie. The subscript is used to determine the position, where the first subscript i represents the type of rail, and the second subscript j, k represents the rail, tie node number along the longitudinal direction from left to right of the i-th rail. Then only contains the node number at the position of the fastener.

[0079] 3) The nodes defined by the rail layer mainly include the rail nodes located at the support of the tie, the rail nodes used to represent the variable cross-section characteristics, and the rail nodes corresponding to the installation position of the longitudinal force transmission component. The nodes defined by the tie layer only involve the ties that need to be provided with fasteners.

[0080] 4) Combined with the information of the rail nodes and the key characteristic sections, the variable cross-section rail elements are defined in sequence, and the direction angle of each rail element is determined 、 Length and element stiffness .

[0081] Step 2: Boundary condition and equilibrium equation construction

[0082] 1) The present application mainly focuses on the longitudinal evolution problem of seamless turnout, therefore only the longitudinal degree of freedom of the rail is considered in the modeling process.

[0083] 2) A certain length of extension section is needed at the front and rear ends of the seamless turnout to eliminate the influence of boundary effect, and corresponding boundary conditions are set according to the actual constraint state of different rails. Among them, the basic rail adopts fixed end constraint at both ends; the center rail only applies fixed end constraint at the end; the switch rail-lead rail-wing rail does not have fixed end constraint at both ends, and is only constrained by the rail fastener system.

[0084] 3) In the ballastless seamless turnout system, according to the longitudinal resistance-displacement relationship slope function of the fastener, spacer, and spacer, the displacement equilibrium equation of the rail node is established respectively.

[0085] 4) Two cases are distinguished according to whether there is a concentrated force in the middle of the rail element, and the corresponding relationship between the longitudinal force state of the rail element and the longitudinal displacement difference of the two end nodes is established through Hooke's law.

[0086] Step 3: Resistance curve drift analysis and equivalent treatment (resistance curve drift theory and equivalent principle)

[0087] 1) Obtain the longitudinal resistance-displacement time series data of the seamless turnout in the actual service process. Under the action of reciprocating load, the fastener resistance shows hysteresis characteristics. In this process, the origin of the resistance curve will drift, and the cumulative effect of residual plastic displacement will be caused. The load history is divided into M+1 load steps, that is Based on the load step, the fastener resistance-displacement time series data during the service phase are discretized to obtain the rail displacement at each load step. Fastener resistance .

[0088] 2) By combining the longitudinal resistance-displacement time series data, the origin drift of the fastener resistance curve under each load step is further determined. Constitutive Relationship of Resistance-Displacement Curve Here middle This is used to determine the functional relationship between fastener resistance and rail displacement under this load step, where x represents the displacement variable of the function. This refers to the last intersection of the drag-displacement curve with the x-axis, assuming drag degradation is not considered. Compared to exist x Axial direction deviates from the origin of coordinates .

[0089] 3) If for the first LSQ To reconstruct the service state of a seamless turnout under various load steps, it is necessary to perform equivalent calculations from three aspects: rail stress state, fastener constitutive relationship, and load path. Since each rail node of the seamless turnout experiences a different load cycle, it is necessary to solve for each rail node connected to the fastener separately.

[0090] 4) To restore the rail stress state during service, it is necessary to ensure that the rail node displacement is reduced from the initial displacement. Change to the number LSQ Displacement of each load step .

[0091] 5) Regarding the constitutive relationship of the fasteners, a forced displacement is applied to the nodes of the fasteners at the sleeper layer to compensate for the drift effect of the resistance curve under cyclic load. That is... , At this point, the resistance-displacement curves of each fastener are converted into constitutive curves passing through the origin, and there is a lateral coordinate offset between the fastener resistance coordinate system and the overall coordinate system of the rail node. .

[0092] 6) Regarding the load path, after compensating for the drag curve drift effect, determine the loading / unloading state of the rail nodes and solve for the rail nodes. along Depend on( ,0) Move to ( , The equivalent load path experienced .in, When node If it is in the loading state, then , if the state is unloading, then is the demarcation point between loading and unloading state.

[0093] The solved The equivalent load path is established, and the state of the turnout is restored by multi-load step iteration:

[0094] ; (1)

[0095] In the formula, is the actual temperature load received by the turnout in service state under the LSQ load step.

[0096] Step 4: Dynamic updating of resistance parameters (resistance curve updating algorithm)

[0097] 1) If it is necessary to update the resistance parameters in subsequent calculations, the original point drift amount and the loading and unloading path can be calculated based on the initial resistance curve for further correction.

[0098] 2) According to , a steel rail node state judgment logic matrix can be constructed . In this logic matrix, the value 0 represents the loading state, and the value 1 represents the unloading state.

[0099] 3) According to the field fastener torque and the state of the rail under the rubber pad, etc. to judge the actual degradation degree of the resistance parameters, and determine the resistance curve to be updated. Assuming that after considering the updating of the resistance parameters, the resistance curve drift amount and the change amount of the loading and unloading path are represented by , respectively, then they can be corrected by the following formula:

[0100] ; (2)

[0101] ; (3)

[0102] ; (4)

[0103] ; (5)

[0104] ; (6)

[0105] In the formula, cor 1, ela , cor 2 is the intermediate process quantity needed to be determined when solving the resistance curve drift amount and the change amount of the loading and unloading path; k , kt are the longitudinal stiffness of the original resistance curve and the degradation curve in the elastic stage, respectively; represent the firstLSQ Load step update resistance parameter; R a represents the maximum resistance value of the fastener resistance under the original resistance curve condition in the elastic stage; , respectively represent the fastener resistance of the rail node under displacement , the loading function decomposed by the constitutive relation curve , and the inverse function thereof.

[0106] 4) According to the change amount, the resistance curve drift amount, the loading and unloading path and the like are updated again:

[0107] ; (7)

[0108] ; (8)

[0109] ; (9)

[0110] Step 5: Nonlinear solving and model building (Newton-Raphson nonlinear solving)

[0111] 1) The rail node displacement matrix and the overall stiffness matrix of the structure are formed by combining the foregoing analysis, and the nonlinear force balance equation is formed.

[0112] 2) When performing multi-load step analysis, the equivalent load step is first applied to restore the longitudinal service state of the seamless turnout, and then the load conditions required for subsequent analysis are applied.

[0113] 3) In the iterative calculation process, the force state needs to be judged, the influence of geometric nonlinearity needs to be considered, and the nonlinear equation set needs to be updated accordingly.

[0114] 4) The solving process adopts Newton-Raphson for nonlinear iterative calculation, and the convergence of the result is judged according to the force and displacement convergence criteria.

[0115] The advantage of the present application is that the existing seamless turnout modeling theory is extended, so that the seamless turnout safety evaluation model is extended from the design stage to the service stage. The present application can fully consider the real situation of residual deformation and residual stress of the seamless turnout, restore the service state of each node of the seamless turnout rail according to the physical and mechanical mechanism, and dynamically update the resistance parameters. In the modeling process, the fastener-displacement historical data need to be referred to, so that the effective combination with the field monitoring data can be realized. In contrast, if the digital twin technology is used without considering the stress and deformation accumulation of the seamless turnout in the service process, the local position accuracy may be high, but the overall prediction accuracy of the model may be poor.​

[0116] To evaluate the accuracy of the reconstructed model of the turnout in service state and its long-term stability in subsequent calculation, the following verification is performed: a turnout in ideal design state is constructed by using the traditional modeling method, and cyclic loads are applied to it. The track states A and C corresponding to a certain load step are selected as the verification group. State A is used as the target state of the reconstructed model and the reference benchmark; state C is used to evaluate the accuracy and stability of the reconstructed model in subsequent calculation. It can be seen from Figure 3 、 Figure 4 and Figure 5 that the states B and D reconstructed by combining the displacement and resistance data are highly consistent with the states A and C of the verification group. The longitudinal displacement error of the rail is controlled within 2× mm, and the maximum error of the longitudinal force is only 0.02 kN. Figure 3 In the above, model 1 is the initial design state model, and model 2 is the reconstructed model in service state.

[0117] In addition, the effect of the fastener resistance update is verified by a daily track temperature cycle example with an amplitude of 55°C (maximum temperature drop of -45°C and maximum temperature rise of 10°C). As shown in Figure 6 , during the 25-day daily track temperature cycle, although the resistance parameters are updated on the 6th day, the fastener-displacement resistance curve is still smooth and continuous, which can confirm that the proposed resistance parameter update algorithm can effectively ensure the stability and continuity of the turnout state in the cyclic calculation process.

[0118] The above-described embodiments are used to illustrate the present application and are not intended to limit the present application, so the numerical values of the examples or the replacement of equivalent elements should still belong to the scope of the present application.

[0119] From the above detailed description, it can be clear to those skilled in the art that the present application can indeed achieve the aforementioned purposes and has met the requirements of the Patent Law.

[0120] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to these embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application. The above description is only for the preferred embodiments of the present application and is not intended to limit the present application. It should be noted that any modification, equivalent replacement and improvement made within the spirit and principles of the present application should be included in the protection scope of the present application.

[0121] It should be noted that the foregoing description of processes is merely illustrative and explanatory and is not intended to limit the scope of the application. Various modifications and changes can be made to the processes by those skilled in the art, which modifications and changes are intended to fall within the scope of the application.

[0122] Having described the basic concepts, it is obvious to those skilled in the art that the above-described disclosure of the application is merely illustrative and not restrictive. Although not explicitly described, various modifications, improvements, and changes can be made to the application by those skilled in the art. Such modifications, improvements, and changes are suggested in the application, so such modifications, improvements, and changes still fall within the spirit and scope of the exemplary embodiments of the application.

[0123] Meanwhile, specific words are used in the application to describe the embodiments of the application. For example, "one embodiment", "an embodiment", and / or "some embodiments" mean a certain feature, structure, or characteristic that relates to at least one embodiment of the application. Therefore, it should be emphasized and noted that the "one embodiment" or "one alternative embodiment" mentioned in different places in the specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be properly combined.

[0124] In addition, those skilled in the art can understand that aspects of the application can be described and claimed in a number of patentable aspects or claims, including any new and useful processes, machines, products, or compositions of matter, or any new and useful improvements thereof. Therefore, various aspects of the application can be implemented entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. The above hardware or software can be referred to as "units", "modules", or "systems". In addition, aspects of the application can take the form of a computer program product embodied in one or more computer-readable media, in which computer-readable program code is contained.

[0125] The operations of various parts of the application can be implemented in conjunction with parametric modeling of finite element software such as ANSYS, or can be implemented through programming. The computer program code required to implement the present application can be written in any one or more programming languages, including an object oriented programming language such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, Python, etc., a conventional procedural programming language such as the C programming language, Visual Basic, Fortran 2103, Perl, COBOL 2102, PHP, ABAP, a dynamic programming language such as Python, Matlab, Ruby and Groovy, or other programming languages. This program code can execute entirely on the user's computer, or it can execute as a standalone software package, or it can execute partly on the user's computer and partly on a remote computer or server, or it can execute entirely on a remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider), or in a cloud computing environment, or as a service such as Software as a Service (SaaS).

[0126] In addition, the order of execution or performance of the operations of the embodiments of the application illustrated and described herein is not essential, unless otherwise specified. That is, the operations can be performed in any order, unless otherwise specified, and the embodiments of the application can include additional or even other operations than those disclosed and described herein. For example, operational data can be arranged, accessed or stored in any memory or memory location and can be transmitted, conveyed or received using any communication medium or interface. While various elements of the disclosed application can be shown as being implemented in hardware, software or a combination of hardware and software, it will be apparent that any feature described herein can be implemented, individually or in any combination, using hardware alone, software alone or any combination thereof.

[0127] It should also be noted that, as used in the specification and the claims, the singular form "a", "an" and "the" include plural references unless the context clearly dictates otherwise. For example, a component can include one or more components. As used herein, the expression "and / or" includes combinations of one or more of the associated listed items. As used herein, the expression "at least one of A and B" is intended to mean A or B or both A and B. Similarly, "at least one of A or B" is intended to mean A or B or both A and B. As used herein, the expression "one or more of A, B and C" is intended to mean A or B or C or any combination thereof. As used herein, the expression "one or more of A, B or C" is intended to mean A or B or C or any combination thereof.

Claims

1. A method for constructing a longitudinal evolution model of an in-service ballastless seamless turnout considering resistance update, characterized in that, The application relates to a method for simulating the stress state of a rail in a ballastless continuous turnout. Step 1: parameterized modeling of the ballastless continuous turnout; The finite element method and parameterization are adopted to construct a ballastless continuous turnout model containing rails, fastenings, limiters and interval irons, rail nodes and sleeper nodes are defined, the variable cross-section rail unit is defined by combining the rail nodes and key characteristic section information, and the direction angle, length and unit stiffness of the variable cross-section rail unit are determined; Step 2: construction of boundary conditions and equilibrium equations; Only the longitudinal freedom of the rail is considered, the extended sections are arranged at the front and rear ends of the ballastless continuous turnout to eliminate the boundary effect and the boundary conditions are arranged according to the actual constraints, the rail node displacement equilibrium equation is established according to the longitudinal resistance-displacement relationship slope function of the fastenings, limiters and interval irons, and the corresponding relationship between the rail unit longitudinal stress and the node displacement difference is established according to the Hook's law; Step 3: resistance curve drift analysis and equivalent treatment; The longitudinal resistance-displacement time sequence data of the ballastless continuous turnout in the service process are acquired and are discretized according to load steps, the original point drift amount and the constitutive relationship of the fastening resistance curve under each load step are determined, and equivalent treatment is carried out from three aspects of the rail stress state, the fastening constitutive relationship and the load path for the target load step; Step 4: dynamic updating of the resistance parameters; Based on the initial resistance curve related data, the rail node state discrimination logic matrix is constructed, and according to the actual degradation degree of the resistance parameters, the original point drift amount of the fastening resistance curve, the load path and the constitutive relationship are corrected, and the dynamic updating of the resistance parameters is realized; Step 5: nonlinear solving and model construction; The nonlinear stress balance equation is constructed by combining the parameterized information of the ballastless continuous turnout model determined in step 1, the displacement balance equation established in step 2, the original point drift amount of the fastening resistance curve and the equivalent treatment process obtained in step 3 and the change amount of the original point drift amount and the load path of the fastening resistance curve deduced in step 4, the multi-load step analysis is carried out, the nonlinear iterative calculation is carried out by adopting the Newton-Raphson method, the result is judged according to the convergence criterion, and the model construction is completed.

2. The method according to claim 1, wherein, In step 1, the nodes of each rail are divided along the longitudinal direction according to a preset interval, and the preset interval is determined according to the sleeper arrangement interval, the longitudinal force transmission component installation position and the variable cross-section position of the rail, and the sleeper nodes are arranged only at the turnout sleeper positions with fastenings.

3. The method according to claim 1, wherein, In step 2, the length of the rail extended section is determined according to the total length of the ballastless continuous turnout and the influence range of the boundary effect, and the rail type of the extended section is consistent with the rail type of the ballastless continuous turnout connected therewith.

4. The method according to claim 1, wherein, In step 2, the longitudinal resistance-displacement relationship slope function is obtained by piecewise linear fitting after the longitudinal resistance measured data of the fastenings, limiters and interval irons under different displacements are acquired.

5. The method according to claim 1, wherein, In step 2, the stress and deformation relationship of the rail unit is established according to whether the longitudinal concentrated force exists in the middle of the rail unit, and the concentrated force includes the longitudinal force transmitted by the limiters and interval irons.

6. The method according to claim 1, wherein, In step 3, the last intersection point of the resistance-displacement time sequence curve of the fastening from the initial load step to the current load step is the original point drift amount.

7. The method according to claim 1, wherein, In step 3, the forced displacement is applied to the sleeper node to realize the rapid compensation of the resistance curve drift effect in the service period.

8. The method according to claim 1, wherein, In step 3, the load path refers to the displacement of the rail node following the slope of the fastener resistance curve. The displacement trajectory changes from the drift amount of the origin of the fastener resistance curve to the target displacement. Specifically, it is divided into two cases: one is a single loading path; the other is a composite path composed of a loading path and an unloading path.

9. The method according to claim 1, wherein, In step 4, when constructing the state discrimination logic matrix, the value 0 in the matrix represents the loading state, and the value 1 represents the unloading state. The discrimination of the state depends on whether the two consecutive displacements in the load path solved in step 3 are equal. If they are equal, it is determined as loading, otherwise it is determined as unloading.

10. The method according to claim 1, wherein, In step 5, in the multi-load step analysis, the equivalent load is first applied to reconstruct the service state of the seamless turnout, and then the subsequent load conditions to be analyzed are applied. In each load step iteration calculation, force and displacement convergence criteria judgment is required.

Images