Deterioration coupling modeling method for on-rail and under-rail structures in ballastless track system

Abstract

The invention discloses an on-rail and under-rail structure degradation coupling modeling method in a ballastless track system, and belongs to the technical field of railway track safety analysis control engineering. Aiming at the problems that the ballastless track coupling system is difficult to analyze under a multi-factor degradation working condition and is limited to single structure degradation analysis, the method comprises the following steps: establishing a train subsystem by applying a UM Input program; finite element software ABAQUS is utilized to establish a plate-type ballastless track finite element model comprising a track, a roadbed and a foundation structure, and a structure, needing to be added with deterioration, of an under-track system is set to complete grid division; importing the established ballastless track finite element model into UM Input, and establishing a connection relation and a boundary condition of each layer structure of the under-track system; in the UM Input, a flexible body track is added, and a vehicle-track-road-ground coupling system is established; in UM simulation, basic parameters are set, and a structure, needing to be added with deterioration, of an on-rail system is set.

Description

Technical Field

[0001] The present invention belongs to the technical field of railway track safety analysis and control engineering, and particularly relates to a coupling modeling method for deterioration of the on-track and under-track structures in a ballastless track system. Background Art

[0002] With the continuous increase in train operation speed and the increase in operation mileage, various structures in the high-speed railway system have shown varying degrees of damage conditions. Although the train components and track structures are regularly inspected and maintained, the relevant mechanisms have mostly not been explored. Accidents are often not dominated by a single factor but are caused by multiple deteriorations within the system, which ultimately reflects in wheel-rail contact. Therefore, it is a trend to consider the combined action of multi-factor deteriorations from a systematic perspective for analysis.

[0003] The investment in high-speed railway line tests is large and the cycle is long. The high cost forces researchers to find alternative ways. With the popularization and development of computer technology, the analytical method has provided a new research approach for the coupled system dynamics analysis, and simulation has become the mainstream research method. Existing research has confirmed that the simulation analysis results are relatively reliable.

[0004] Regarding the deterioration phenomena such as wheel surface scratches, rail wear, fastener system failure, slab deterioration, mortar layer voids, base slab cracking, and uneven subgrade settlement within the high-speed railway ballastless track coupling system, existing research has focused on the cause exploration and dynamic response analysis of each individual phenomenon, and simplified other structures outside the damaged structure. In engineering practice, the wheels are not ideal circles, the tracks are not completely straight, and the repeated excitation of vehicle loads causes the stiffness of the fastener system to decrease and soil settlement to occur in the under-track system. These phenomena exist at all times during the operation of high-speed railways, and the industry standards for the service performance of each structure are also different. Therefore, when conducting dynamic analysis, it is necessary to uniformly set the industry standards to cover the service performance evaluation indicators of each structure. Summary of the Invention

[0005] Aiming at the problems that the analysis of the ballastless track coupling system is difficult under the condition of multi-factor deterioration, and it is limited to the single-structure deterioration analysis of the track or sub-track, the present invention provides a dynamic modeling method for the ballastless track high-speed railway coupling system with structural deterioration existing simultaneously in the track and sub-track systems based on finite element software and multi-body dynamics software, and uses the Universal Mechanism multi-body dynamics software to establish a train model. The Universal Mechansim multi-body dynamics software (referred to as UM software for short) is a multi-body dynamics simulation software developed by the famous mathematician and mechanics expert Dmitry Pogorelov and his team members from the Bryansk State University in Russia, and it includes the pre-processing UM Input and the post-processing UMSimulation programs; uses the ABAQUS finite element software to establish the CRTS I type slab ballastless track, subgrade, and foundation structures; completes the conversion of the finite element model through ABAQUS_UM_XE.exe; establishes a complete vehicle-track-road-ground coupling system in UM Input, and in UM Simulation, sets the fastener connection relationship and basic track parameters; by applying various deterioration diseases, studies the influence of the simultaneous structural deterioration on the dynamic response of the vehicle-track-road-ground coupling system, and provides operation and maintenance suggestions for the relevant railway departments.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A coupling modeling method for the structural deterioration of the track and sub-track in the ballastless track system, including the following steps:

[0008] Step 1, use the UM Input program in the multi-body dynamics software to establish a train subsystem;

[0009] Step 2, use the finite element software ABAQUS to establish a finite element model of the slab ballastless track including the track, subgrade, and foundation structures, set the structures that need to add deterioration to the sub-track system, and then complete the mesh division;

[0010] Step 3, import the established finite element model of the ballastless track into the UM Input program, and establish the connection relationship and boundary conditions of each layer structure of the sub-track system;

[0011] Step 4, in the UM Input program, add a flexible body track to establish a vehicle-track-road-ground coupling system;

[0012] Step 5, in the UM Simulation program, set the basic parameters, covering the fastener spacing and parameters, rail profile, wheel tread shape, and ballastless track irregularity spectrum;

[0013] Step 6, set the structures that need to add deterioration to the track system to complete the coupling modeling.

[0014] Furthermore, in step 1, the UM Input program in the multi-body dynamics software is used to establish a train subsystem model, which includes the following steps:

[0015] Step 1.1: The train subsystem is regarded as consisting of a car body and two bogies. One bogie includes a frame and two wheel sets, and the frame and the wheel sets are connected by primary suspension, while the car body and the frame are connected by secondary suspension;

[0016] Step 1.2: In the Subsystems module of the UM Input program, create a wheel set model and set the mass, moment of inertia, nominal radius, and axle length of the wheel set; then, sequentially add the images of the car body, secondary dampers, frame, primary dampers, air springs, and axle boxes; set the mass, moment of inertia, and centroid coordinates of the frame; set the vertical stiffness, lateral stiffness, and longitudinal stiffness of the primary spring, as well as the damping parameters of the primary vertical damper; create an axle box swing arm node and set the vertical stiffness, lateral stiffness, and longitudinal stiffness of the axle box swing arm node; create secondary air springs, secondary vertical dampers, secondary lateral dampers, and anti-hunting dampers, and respectively set the stiffness and damping parameters of the secondary air springs, secondary vertical dampers, secondary lateral dampers, and anti-hunting dampers;

[0017] Step 1.3: Build a car body model and set the mass, moment of inertia, and centroid coordinates of the car body, thus completing the establishment of the train subsystem model.

[0018] Furthermore, in step 2, the finite element software ABAQUS is used to establish a finite element model of the slab ballastless track including the track, subgrade, and foundation structure, and set the structures that need to be deteriorated in the track sub-system, and then complete the mesh division, which specifically includes the following steps:

[0019] Step 2.1: Divide the track sub-system into a track subsystem, a subgrade subsystem, and a foundation subsystem. The track subsystem includes a track slab, a CA mortar layer, a base slab, and a concrete asphalt layer; the subgrade subsystem includes a subgrade surface layer, a subgrade bottom layer, and an embankment body; the foundation subsystem is treated as a half-space elastic body; according to the actual structural dimensions of the CRTS I type slab ballastless track in high-speed railways, use the ABAQUS finite element software to complete the establishment of the finite element model of the track sub-system;

[0020] Step 2.2: Use the cutting and deletion operation on the structural layer to complete the deterioration setting of structural voids. Cut the structural layer without separating it, and assign the deteriorated material parameters to the deteriorated section to complete the deterioration setting of the stiffness reduction of each structural layer; locally rigidify the four corner points of the bottom surface of each structural layer, and complete the mesh division of each layer of structure according to the elastic wave propagation principle; reserve the mesh nodes of the fasteners for the connection of the rail and the track slab.

[0021] Further, in step 3, the established ballastless track model is imported into the UM Input program to establish the connection relationships and boundary conditions of each layer structure under the rail, specifically including the following steps:

[0022] Step 3.1, extract the first 30 natural frequencies of each layer structure model established by ABAQUS, save the results to the ABAQUS.fil file using the dynamic substructure method; convert the ABAQUS.fil file to the input.fum file through the ABAQUS_UM_XE.exe interface; in the Wizard of Flexible Subsystems module of UM, import the input.fum file, and complete modal regularization after removing the rigid body modes, finally generating the input.fss file; in the Linear FEM Subsystem in the Subsystems module, select the input.fss file and load the model, thus completing the import of the track system model under the rail;

[0023] Step 3.2, establish the connection relationships and boundary conditions between each layer in the track system under the rail, use the penalty function method to simulate the contact relationships between layers, and use bushing force elements to connect the corresponding nodes between layers; the boundary conditions of the track system under the rail adopt artificial elastic boundaries to ensure that the train load stress wave does not repeatedly propagate inside.

[0024] Further, in step 4, in the UM Input program, add a flexible body track to establish a vehicle-track-road-ground coupling system, specifically including the following steps:

[0025] Step 4.1, add a flexible body track as the track type to facilitate the connection of the train subsystem and the track system under the rail;

[0026] Step 4.2, move the train a certain distance along the longitudinal distance, divide the dynamic simulation process into three running stages: before the flexible rail, on the rail, and after the rail, to facilitate reducing the boundary effect, and take the section where the flexible body travels as the research object.

[0027] Further, in step 5, in the UM Simulation program, set the basic parameters, covering the fastener spacing and parameters, rail profile, wheel tread shape, and ballastless track irregularity spectrum, specifically including the following steps:

[0028] Step 5.1, set the center line of the rail of the flexible body track, the fastener spacing, and the stiffness and damping parameters of the fasteners;

[0029] Step 5.2, select the LMA type worn tread for the wheel tread shape, select the CN60 steel rail for the rail profile, endow the rail material with the parameters related to wheel-rail contact, set it as the straight track type, and endow the rail base slope parameter;

[0030] Step 5.3: Rail unevenness adopts the unevenness spectrum of China's high-speed railway ballastless track.

[0031] Furthermore, the step 6 is to set the structure of the on-rail system to be degraded, which specifically includes the following steps:

[0032] Step 6.1, uncheck the bushing force element in the fastener failure section in the Forces module to simulate the fastener failure without support conditions; add the wheelset wear condition in Out-of-round;

[0033] Step 6.2, perform simulation calculations to compare changes in dynamic responses under normal conditions and deteriorated conditions.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] The present invention divides the high-speed railway coupling system into a train subsystem, a track subsystem, a roadbed subsystem and a foundation subsystem. According to the current operating status of the high-speed railway slab ballastless track system, the coupling model is established by using finite element software and multi-body dynamics software. The model can accurately reflect the transmission law of the internal dynamic response of the system and the deformation characteristics of each structure. Compared with the study of the dynamics of the sub-track system by transforming the train load in the form of a function, and the study of the train system by treating the sub-track structure as a macroscopic non-deformable elastic body, the present invention constructs a complete car body and sub-track system model to truly reflect the train service environment. Previous studies were often limited to the degradation of a single structure on or under the track. The present invention couples the on-track and under-track systems, and takes into account the impact of the on-track and under-track structural degradation on the system. It restores the degradation conditions of mortar layer degassing, base bed surface graded gravel powderization, rail fastener system, wheel polygons, and wheel flats. It judges the vehicle running quality when one or more degradation conditions occur simultaneously in the on-track and under-track systems, and warns of accidents that may be caused by degradation conditions, providing certain theoretical references for relevant practitioners in design and operation and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a flow chart of the method of the present invention;

[0037] Figure 2 This is a train model diagram;

[0038] Figure 3 Finite element model diagram of the sub-track system

[0039] Figure 4 This is the dynamic model diagram of the high-speed railway ballastless track coupling system;

[0040] Figure 5It is a schematic diagram of the hollowing out of the mortar layer;

[0041] Figure 6 It is a schematic diagram of the failure of a single-side fastener;

[0042] Figure 7 Apply schematic diagram for degraded conditions;

[0043] Figure 8 It is a comparison diagram of wheel-rail force amplitude under deteriorated conditions;

[0044] Figure 9 Schematic diagram of single-side fastener failure

[0045] Figure 10 It is a comparative schematic diagram of fastener failure and mortar layer decompression and deterioration conditions. DETAILED DESCRIPTION

[0046] In order to gain a deeper understanding of the present invention, we will provide a comprehensive and detailed description of the present invention. However, the present invention has multiple implementations and is not limited to the specific examples listed below. The presentation of these examples is intended to deepen the comprehensive understanding of the disclosure of the present invention.

[0047] This embodiment takes a train running at a constant speed of 350km / h as an example to explain the method provided by the present invention in detail. The vehicle adopts the vehicle parameters of a single-section train of a certain EMU of China's high-speed railway, wherein the vehicle fixed distance is 18m, the wheelbase is 2.5m, the body mass is 39.6t, the bogie mass is 3.5t, the wheel set mass is 2t, the wheel rolling circle radius is 0.457m, and the wheel profile adopts the ChineseLMA type wear-type tread. The rail adopts the standard CN60 rail profile, the fastener stiffness is 3.5e7N / m, the fastener damping is 4.8e4N·s / m, the track plate thickness is 0.2m, the CA mortar layer thickness is 0.05m, the base plate thickness is 0.3m, the concrete asphalt layer thickness is 0.1m, the subgrade surface layer, subgrade bottom layer, and embankment body thickness are 0.4m, 2.3m, and 3m respectively, and the foundation soil thickness is 5m. The track unevenness uses the uneven track spectrum of China's high-speed railway ballastless track.

[0048] like Figure 1 The flowchart shown is a method for coupling modeling of degradation of the track and sub-track structures in a ballastless track system under multiple degradation conditions based on the combination of finite element software ABAQUS and multi-body dynamics software UM. The vehicle subsystem model is implemented by UM software, the sub-track system model is implemented based on finite element software ABAQUS, and multiple degradation factors are added by the function of the post-processing module of the UMSimulation program;

[0049] The present invention comprises the following steps:

[0050] Step 1, use the UM Input program in the multi-body dynamics software to establish the train subsystem;

[0051] Step 1.1: Consider the train subsystem as consisting of a car body and two bogies. One bogie includes a frame and two wheel sets. The frame and the wheel sets are connected by primary suspension, and the car body and the frame are connected by secondary suspension.

[0052] Step 1.2: In the Subsystems module of the UM Input program, create a wheel set model and set the mass, moment of inertia, nominal radius, and axle length of the wheel set. Then, sequentially add the images of the car body, secondary dampers, frame, primary dampers, air springs, and axle boxes. Set the mass, moment of inertia, and centroid coordinates of the frame. Set the vertical stiffness, lateral stiffness, and longitudinal stiffness of the primary springs, and the damping parameters of the primary vertical dampers. Create the axle box swing arm nodes and set the vertical stiffness, lateral stiffness, and longitudinal stiffness of the axle box swing arm nodes. Create the secondary air springs, secondary vertical dampers, secondary lateral dampers, and anti-hunting dampers, and set the stiffness and damping parameters of the secondary air springs, secondary vertical dampers, secondary lateral dampers, and anti-hunting dampers respectively.

[0053] Step 1.3: Build the car body model and set the mass, moment of inertia, and centroid coordinates of the car body, thus completing the establishment of the train subsystem model.

[0054] Step 2: Use the finite element software ABAQUS to establish a finite element model of the slab trackless ballast track including the track, subgrade, and foundation structure, and set the structures that need to be degraded in the track sub-system, and then complete the mesh generation.

[0055] Step 2.1: Divide the track sub-system into a track subsystem, a subgrade subsystem, and a foundation subsystem. The track subsystem includes a track slab, a CA mortar layer, a base slab, and a concrete asphalt layer; the subgrade subsystem includes a surface layer of the subgrade bed, a bottom layer of the subgrade bed, and the embankment body; the foundation subsystem is treated as a semi-space elastic body. According to the actual structural dimensions of the CRTS I type slab trackless ballast track in high-speed railways, use the ABAQUS finite element software to complete the establishment of the finite element model of the track sub-system.

[0056] Step 2.2: Use the cutting and deletion operation on the structural layer to complete the degradation setting of structural voids. Cut the structural layer without separating it, and assign the degraded material parameters to the degraded section to complete the degradation setting of the stiffness reduction of each structural layer. Rigidify the four corner points at the bottom of each structural layer locally, and complete the mesh generation of each layer of structure according to the elastic wave propagation principle. Reserve the mesh nodes of the fasteners for connecting the rail and the track slab.

[0057] Step 3: Import the established ballastless track model into the UM Input program to establish the connection relationships and boundary conditions of each layer structure under the track.

[0058] Step 3.1: Extract the first 30 natural frequencies of each layer structure model established by ABAQUS, and use the dynamic substructure method to save the results to the ABAQUS.fil file; convert the ABAQUS.fil file to the input.fum file through the ABAQUS_UM_XE.exe interface; in the Wizard of Flexible Subsystems module of UM, import the input.fum file, and complete modal regularization after removing the rigid body modes, and finally generate the input.fss file; in the Linear FEM Subsystem in the Subsystems module, select the input.fss file and load the model to complete the import of the under-rail system model.

[0059] Step 3.2: Establish the connection relationships and boundary conditions between the layers in the under-rail system, use the penalty function method to simulate the contact relationships between the layers, and use bushing force elements to connect the corresponding nodes between the layers; the boundary conditions of the under-rail system adopt artificial elastic boundaries to ensure that the train load stress wave does not repeatedly transmit inside.

[0060] Step 4: Add a flexible track in the UM Input program to establish a vehicle-rail-road-ground coupling system.

[0061] Step 4.1: Add a flexible track as the track type to facilitate the connection of the train subsystem and the under-rail system.

[0062] Step 4.2: Move the train a certain distance along the longitudinal direction, and divide the dynamic simulation process into three running stages: before the flexible rail, on the rail, and after the rail, to facilitate reducing the boundary effect, and use the driving section of the flexible body as the research object.

[0063] Step 5: Set the basic parameters in the UM Simulation program, covering the fastener spacing and parameters, rail profile, wheel tread shape, and ballastless track irregularity spectrum.

[0064] Step 5.1: Set the center line of the flexible track rail, fastener spacing, stiffness and damping parameters of the fasteners.

[0065] Step 5.2: Select the LMA type worn tread for the wheel tread shape, select the CN60 steel rail for the rail profile, endow the rail material with parameters related to wheel-rail contact, set it as a straight track type, and endow the rail cant parameter.

[0066] Step 5.3: Adopt the ballastless track irregularity spectrum of China's high-speed railway for the rail irregularity.

[0067] Step 6: Set the structures that need to be deteriorated in the on-rail system.

[0068] Step 6.1, uncheck the bushing force elements in the failed section of the fasteners in the Forces module to simulate the condition of no support when the fasteners fail; add the wear condition of the wheelset in Out-of-round.

[0069] Step 6.2, perform simulation calculations and compare the changes in the dynamic responses under normal conditions and degraded conditions.

[0070] Figure 2 It is a model diagram of a single-section train, including the wheelset, bogie, car body, suspension system and various shock absorbers. Among them, the wheelset, bogie and car body structures have 5 degrees of freedom except in the train's forward direction.

[0071] Figure 3 It is a schematic diagram of the ballastless track high-speed railway structure. The model is regarded as a structure composed of track slab, CA mortar layer, base slab, concrete asphalt layer, subgrade surface layer, subgrade bottom layer, embankment body and foundation soil. Set the geometric parameters of each layer structure according to the actual track construction process and endow it with material properties; locally rigidify the four corners of the bottom surface of each structural layer, and the mesh division should make the meshes of each structural layer correspond one by one up and down to ensure the establishment of connection relationships in UM. At the same time, the position of the fasteners needs to be divided in the track slab to facilitate the connection of the rail and the track structure.

[0072] Figure 4 It is a model diagram of the dynamic model of the ballastless track coupling system for high-speed railways. Import each layer of the subgrade foundation into the UMInput program respectively, use the bushing force element to simulate the connection relationship between layers, and complete the setting of boundary conditions at the same time; add a flexible body track structure to complete the connection between the vehicle and the subgrade system, and move the vehicle forward to a position where it does not contact the flexible body of the subgrade system.

[0073] Figure 5 It is a schematic diagram of the model of the mortar layer void under the rail. The severe situation of structural degradation can be simulated by controlling different void lengths. When the void length is 0, it is the normal condition.

[0074] Figure 6 It is a schematic diagram of the structural degradation of the subgrade surface layer under the rail. Simulate the degraded condition by cutting the model without separating and modifying the material parameters of the degraded area.

[0075] Figure 7 It is a schematic diagram of the method for adding wheel polygon wear. Input harmonic wear through Out-of-round in the Wheel / Rail module, and set the order, wave depth, phase of the polygon and the wheels to which the wear is added.

[0076] Figure 8It is a schematic diagram of the method for adding wheel flat scars. The flat wear is input through the Out-of-round in the Wheel / Rail module, and the flat scar type, phase, length, depth, lateral position, and the wheel with added wear are set.

[0077] Figure 9 It is a schematic diagram of single-sided fastener failure. The force elements in the corresponding section are selected through Tools-Forces to simulate the failure of the single-sided fastener system of the track.

[0078] By using the method of the present invention, the wheel-rail force amplitudes under multiple deteriorated working conditions can be obtained and compared with the relevant limit indexes under normal working conditions. Taking fastener failure and mortar layer delamination as examples ( Figure 10 ), the variables that have the most significant influence on specific indexes under multi-factor deterioration conditions can be reflected, so as to give operation and maintenance suggestions to relevant practitioners.

[0079] The content not described in detail in the specification of the present invention belongs to the prior art well-known to those skilled in the art. Although the illustrative specific embodiments of the present invention are described above for the convenience of those skilled in the art to understand the present invention, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions made using the concept of the present invention are within the scope of protection.

Claims

1. A method for coupling modeling of deterioration of superstructure and substructure in a ballastless track system, characterized in that It includes the following steps: Step 1: Use the UM Input program in the multi-body dynamics software to establish the train subsystem; Step 2: Use the finite element software ABAQUS to establish a finite element model of the slab ballastless track including the track, subgrade, and foundation structure, set the structures in the track sub-system that need to be deteriorated, and then complete the mesh division; Step 3: Import the established finite element model of the ballastless track into the UM Input program to establish the connection relationships and boundary conditions of the structures at all levels of the track sub-system; Step 4: In the UM Input program, add a flexible body track to establish a vehicle-track-road-ground coupling system; Step 5: In the UM Simulation program, set the basic parameters, including the fastener spacing and parameters, rail profile, wheel tread shape, and ballastless track irregularity spectrum; Step 6: Set the structures in the track upper system that need to be deteriorated to complete the coupling modeling.

2. The method for coupling modeling of deterioration of the on-track and under-track structures in the ballastless track system according to claim 1, wherein, In Step 1, the UM Input program in the multi-body dynamics software is used to establish the train subsystem, which specifically includes the following steps: Step 1.1: Consider the train subsystem as consisting of a car body and two bogies. One bogie includes a frame and two wheel sets, and the frame and the wheel sets are connected by primary suspension, and the car body and the frame are connected by secondary suspension; Step 1.2: In the Subsystems module of the UM Input program, create a wheel set model and set the mass, moment of inertia, nominal radius, and axle length of the wheel set; then, sequentially add the images of the car body, secondary shock absorber, frame, primary shock absorber, air spring, and axle box; set the mass, moment of inertia, and centroid coordinates of the frame; set the vertical stiffness, lateral stiffness, and longitudinal stiffness of the primary spring, and the damping parameters of the primary vertical shock absorber; create an axle box swing arm node and set the vertical stiffness, lateral stiffness, and longitudinal stiffness of the axle box swing arm node; create secondary air springs, secondary vertical shock absorbers, secondary lateral shock absorbers, and anti-hunting shock absorbers, and set the stiffness and damping parameters of the secondary air springs, secondary vertical shock absorbers, secondary lateral shock absorbers, and anti-hunting shock absorbers respectively; Step 1.3: Build a car body model and set the mass, moment of inertia, and centroid coordinates of the car body to complete the establishment of the train subsystem model.

3. The method for coupling modeling of deterioration of on-track and under-track structures in the ballastless track system according to claim 1, characterized in that In Step 2, the finite element software ABAQUS is used to establish a finite element model of the slab ballastless track including the track, subgrade, and foundation structure, set the structures in the track sub-system that need to be deteriorated, and then complete the mesh division, which specifically includes the following steps: Step 2.1: Divide the track sub-system into a track subsystem, a subgrade subsystem, and a foundation subsystem. The track subsystem includes a track slab, a CA mortar layer, a base slab, and a concrete asphalt layer; the subgrade subsystem includes the subgrade surface layer, the subgrade bottom layer, and the embankment body; the foundation subsystem is treated as a semi-space elastic body; according to the actual structural dimensions of the CRTS I type slab ballastless track in high-speed railways, use the ABAQUS finite element software to complete the establishment of the finite element model of the track sub-system; Step 2.2, perform cutting and deletion operations on the structural layer to complete the deterioration setting of structural voids. Cut the structural layer without separating it, and assign deteriorated material parameters to the deteriorated section to complete the deterioration setting of the stiffness reduction of each structural layer. Locally rigidify the four corner points at the bottom of each structural layer, and complete the mesh division of each layer of structure according to the elastic wave propagation principle. Reserve the mesh nodes of the fasteners for connecting the rail and the track slab.

4. The method for coupling modeling of deterioration of on-track and under-track structures in the ballastless track system according to claim 1, characterized in that In Step 3, import the established ballastless track model into the UM Input program, and establish the connection relationships and boundary conditions of each layer structure under the rail. The specific steps are as follows: Step 3.1, extract the first 30 natural frequencies of each layer structure model established by ABAQUS, and use the dynamic substructure method to save the results to the ABAQUS.fil file. Convert the ABAQUS.fil file to the input.fum file through the ABAQUS_UM_XE.exe interface. In the Wizard of Flexible Subsystems module of UM, import the input.fum file, and complete the modal regularization after removing the rigid body modes, and finally generate the input.fss file. In the Linear FEM Subsystem in the Subsystems module, select the input.fss file and load the model to complete the import of the under-rail system model. Step 3.2, establish the connection relationships and boundary conditions between each layer in the under-rail system, use the penalty function method to simulate the contact relationships between layers, and use bushing force elements to connect the corresponding nodes between layers. The boundary conditions of the under-rail system adopt artificial elastic boundaries to ensure that the train load stress wave does not propagate repeatedly inside.

5. The modeling method of the ballastless track coupling system under the failure of the fastener system and the void between the mortar layers, characterized in that, In Step 4, in the UM Input program, add a flexible body track to establish a vehicle-rail-road-ground coupling system. The specific steps are as follows: Step 4.1, add a flexible body track as the track type to facilitate the connection between the train subsystem and the under-rail system. Step 4.2, move the train a certain distance along the longitudinal direction, and divide the dynamic simulation process into three running stages: before the flexible rail, on the rail, and after the rail, to facilitate reducing the boundary effect, and take the driving section of the flexible body as the research object.

6. The method for coupling modeling of deterioration of on-track and under-track structures in the ballastless track system according to claim 1, characterized in that, In Step 5, in the UM Simulation program, set the basic parameters, covering the fastener spacing and parameters, rail profile, wheel tread shape, and ballastless track irregularity spectrum. The specific steps are as follows: Step 5.1, set the center line of the flexible body track rail, fastener spacing, stiffness and damping parameters of the fasteners. Step 5.2, select the LMA type worn tread for the wheel tread shape, select the CN60 steel rail for the rail profile, assign the parameters related to the rail material and wheel-rail contact, set it as the straight track type, and assign the rail cant parameter. Step 5.3, adopt the ballastless track irregularity spectrum of China's high-speed railway for the rail irregularity.

7. The method for coupling modeling of deterioration of on-track and under-track structures in the ballastless track system according to claim 1, characterized in that In Step 6, set the structures that need to be deteriorated in the on-rail system. The specific steps are as follows: Step 6.1, uncheck the bushing force elements in the failed section of the fasteners in the Forces module to simulate the working condition without support when the fasteners fail; add the wear condition of the wheelset in Out-of-round. Step 6.2, perform simulation calculations and compare the changes in dynamic responses under normal and degraded working conditions.

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