Method for evaluating shear damage evolution of weak interface of track plate-filling layer under cooling effect

Abstract

The invention discloses a method for evaluating shear damage evolution of a weak interface of a track plate-filling layer under a cooling effect. The method comprises the following steps: acquiring a shear stress-slip constitutive relationship between the weak interface of the track plate and the filling layer through a push plate test; according to the cooling shrinkage deformation characteristic of the track slab, dividing the interfacial shear damage evolution into a complete elasticity stage, an elasticity-damage stage and an elasticity-damage-slip stage; based on the shear stress-slippage constitutive relation and damage stage division, mechanical differential equations corresponding to all stages are established and solved, and an interface shear stress distribution analytical solution is obtained; and analyzing an influence rule of the track slab structure parameters and the interface constitutive parameters on shear damage evolution through the analytic solution. According to the method, the problems of efficiency and precision of track plate-filling layer interface shear damage evaluation are solved through combination of tests and an analytical model, and an efficient and reliable theoretical tool is provided for design, maintenance and service life prediction of a high-speed rail track structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of structural damage assessment, and particularly relates to a method for evaluating the shear damage evolution of the weak interface between a track slab and a filling layer under the action of temperature drop. Background Art

[0002] Compared with ballasted tracks, ballastless tracks have the advantages of good ride quality, high stability, and less maintenance in later periods, and have become the main track structure forms for high-speed railways in various countries around the world. The precast slab ballastless track is one of the commonly used ballastless track types in China. The track slabs of this type are precast and polished in the factory, with reliable product quality, highly unified external dimensions, and high standardization and mechanization levels in the construction process. Individual track slabs are connected into a whole through wide and narrow joint post-cast strips to improve the driving safety and comfort. To adjust the installation smoothness of the track slabs and dampen and buffer the driving dynamic loads, cement emulsified asphalt mortar or self-compacting concrete layers are poured between the precast track slabs and the continuously cast base slabs.

[0003] Due to the influence of adverse factors such as untimely longitudinal locking of the track slabs, insufficient quality control of the joint construction between the slabs, and deterioration of the mortar layer, some ballastless track slabs show damage and deterioration during service. Obvious separation phenomena occur at some slab end joint positions, and damage cracks occur at the weak interface between the precast slab ballastless track and the mortar, and the cracks extend longitudinally from the slab end to the middle of the track slab. To optimize the track slab design and maintenance plan, it is of great significance to study the anti-shear working performance of the weak interface.

[0004] In recent years, scholars at home and abroad have carried out many studies on the service damage of ballastless tracks. The relevant research mainly uses numerical simulation to analyze the temperature effect of the ballastless track system, focusing on the warping deformation of the track slab under the action of temperature gradient. There is less research on the shear damage evolution of the weak interface layer under the action of temperature drop. In addition, due to the difficulty in accurately measuring the relative slip of the internal interface in the actual service environment, there is no report on the research of the whole process of stress evolution of the weak interface layer.

[0005] Therefore, it is necessary to propose a method for evaluating the shear damage evolution of the weak interface between a track slab and a filling layer under the action of temperature drop. Summary of the Invention

[0006] To solve the above technical problems, the present invention proposes a method for evaluating the shear damage evolution of the weak interface between a track slab and a filling layer under the action of temperature drop, accurately analyzes the shear damage degradation law of the interface and the influence mechanism of related factors, overcomes the restriction that it is difficult to accurately measure the relative slip of the internal interface in the actual service environment, avoids a large number of numerical simulation trials, and provides a theoretical reference for optimizing the track slab design and maintenance plan.

[0007] To achieve the above object, the present invention provides a method for evaluating the shear damage evolution of the weak interface between a track slab and a filling layer under the action of temperature drop, including:

[0008] Obtain the shear stress - slip constitutive relationship of the weak interface between the track slab and the filling layer through the push - plate test;

[0009] According to the temperature - drop shrinkage deformation characteristics of the track slab, divide the interface shear damage evolution into a fully elastic stage, an elastic - damage stage, and an elastic - damage - slip stage;

[0010] Based on the above - mentioned shear stress - slip constitutive relationship and the division of damage stages, establish the corresponding mechanical differential equations for each stage and solve them to obtain the analytical solution of the interface shear stress distribution;

[0011] Analyze the influence laws of the track slab structural parameters and the interface constitutive parameters on the shear damage evolution through the above - mentioned analytical solution.

[0012] Optionally, the push - plate test includes:

[0013] Apply a longitudinal thrust to the specimen including the track slab, the filling layer, and the base slab, and monitor the curve of the thrust - displacement relationship;

[0014] Determine the ultimate shear resistance, the residual frictional resistance, and the corresponding slip amount of the interface according to the curve, and establish a shear stress - slip three - fold line constitutive model.

[0015] Optionally, the mechanical differential equation of the fully elastic stage is established based on the linear relationship between the shear stress and the slip amount in the elastic stage, and the hyperbolic function analytical solutions of the cross - section stress of the track slab and the interface shear stress distribution are obtained by solving.

[0016] Optionally, the mechanical differential equations of the elastic - damage stage include:

[0017] Based on the shear stress - slip amount three - fold line constitutive relationship, establish the mechanical differential equations of the interface in the elastic region and the damage region respectively;

[0018] Solve the corresponding interface shear stress analytical equations of the elastic region and the damage region through the boundary conditions of the elastic region and the damage region respectively;

[0019] Establish the integral sum of the shear stress of the whole interface and the external load balance equation, and iteratively solve according to the external load to obtain the length of the elastic region and the shear stress distribution of the damage region. Optionally, the mechanical differential equations of the elastic - damage - slip stage include:

[0020] Set the interface shear stress as a constant value of the residual frictional resistance in the slip region;

[0021] Establish a balance equation through the continuity conditions of the slip region and the damage region, and solve the quantitative relationship between the length of the slip region and the temperature - drop amplitude.

[0022] Optionally, the track slab structural parameters include the length, width, thickness, and elastic modulus of the track slab;

[0023] The interface constitutive parameters include the ultimate shear stress, the residual frictional resistance, and the corresponding critical slip amount.

[0024] Optionally, the critical equivalent temperature drop amplitude in the fully elastic stage is obtained by back-calculating from the analytical solution in the elastic stage, specifically: based on the condition that the maximum shear stress in the elastic zone is equal to the interface ultimate shear strength, calculate the corresponding equivalent load and equivalent temperature drop amplitude.

[0025] Optionally, the lengths of different regions of the interface are determined by iteratively solving the stress integral balance equation. The process includes: establishing the integral sum of the shear stress across the entire interface and the external load balance equation, and iteratively solving according to the external load to obtain the interface region lengths and shear stress distributions at different stages.

[0026] Technical effects of the present invention: The present invention discloses a method for evaluating the shear damage evolution of the weak interface between the track slab and the filling layer under the action of temperature drop, which accurately and efficiently analyzes the law of shear damage degradation of the interface and the influence mechanism of related factors, evaluates the shear damage state of the weak interface between the precast track slab and the filling layer of high-speed railways under any temperature drop amplitude, overcomes the restriction that the relative slip of the internal interface is difficult to accurately measure in the actual service environment, avoids a large number of numerical simulation calculations, provides a theoretical reference for the optimization of track slab design and maintenance plans, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings forming a part of this application are used to provide a further understanding of this application. The schematic embodiments and descriptions thereof of this application are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0028] Figure 1 is a schematic flow chart of the method for evaluating the shear damage evolution of the weak interface between the track slab and the filling layer under the action of temperature drop in the embodiment of the present invention;

[0029] Figure 2 is a schematic diagram of the shear stress-slip constitutive relationship of the weak interface in the embodiment of the present invention;

[0030] Figure 3 is a schematic diagram of the force on the weak interface unit in the embodiment of the present invention;

[0031] Figure 4 is a schematic diagram of the stress distribution state of the weak interface at different damage stages in the embodiment of the present invention, where (a) is the elastic stage, (b) is the elastic-damage stage, and (c) is the elastic-damage-slip stage;

[0032] Figure 5 is a schematic diagram of the comparison between the analytical solution of the interface stress and the finite element model results at different damage stages in the embodiment of the present invention, where (a) is the elastic stage, (b) is the elastic-damage stage, and (c) is the elastic-damage-slip stage;

[0033] Figure 6 It is a schematic diagram of the relationship curve between the cooling amplitude and the stress state of the weak interface at different stages of the embodiment of the present invention, where (a) is the elastic stage, (b) is the elastic-damage stage, and (c) is the elastic-damage-slip stage. Detailed implementation manners

[0034] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0035] It should be noted that the steps shown in the flowchart of the drawings can be executed in a computer system such as a set of computer-executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0036] As Figure 1 shown, in this embodiment, a method for evaluating the shear damage evolution of the weak interface between the track slab and the filling layer under the action of cooling is provided, including:

[0037] Step 1: Obtain the shear stress-slip constitutive relationship of the weak interface:

[0038] Use the longitudinal push plate loading and monitoring system of the track slab to obtain its shear-slip constitutive relationship of the weak interface. The system consists of a ballastless track system, a loading system, and a monitoring system. Among them, the ballastless track system (track slab, base slab) is manufactured, installed, and positioned according to the actual structural system composition and dimensions. The interface filling layer is poured using the same raw materials, formula, mixing, and pouring processes as on-site, and after curing to meet the standard requirements according to the actual construction specifications, a push plate test is carried out; the loading system consists of a reaction wall and a synchronous hydraulic jacking system, which is used to apply a uniform and synchronous longitudinal thrust to the plate end; the monitoring system consists of a pressure sensor, a displacement sensor, and a data acquisition instrument, which is used to monitor the corresponding relationship curve between the longitudinal thrust and the displacement. The maximum longitudinal thrust in the curve corresponds to the shear bearing capacity P u of the interface, the interface deformation displacement corresponding to the maximum longitudinal thrust is s u , and the longitudinal thrust at the moment of complete shear failure of the interface corresponds to the residual frictional resistance of the interface (P f ), and the critical deformation displacement corresponding to the residual frictional resistance is s f . Equivalent the corresponding relationship curve between the longitudinal force and the displacement to a shear stress-slip three-line constitutive model. As Figure 2 shown, the critical parameters in the model are expressed as follows:

[0039]

[0040] where s represents the relative interfacial slip, A0 represents the interfacial area, and τ u represents the average interfacial shear stress corresponding to the ultimate shear bearing capacity, and τ f is the average interfacial shear stress corresponding to the residual frictional resistance.

[0041] According to Figure 2 the shown tri-linear constitutive model, the interfacial shear stress τ(x) can be expressed as a function f(s) of the relative displacement s, that is, the interfacial shear stress-slip constitutive relationship can be described by Equation (2).

[0042]

[0043] Step 2: Establish and solve the analytical equation for shear damage evolution.

[0044] Under the overall temperature drop of the track slab, the track slab undergoes symmetric shrinkage deformation. Since the base slab is a longitudinally continuous cast-in-place structure, it can be assumed that the base slab has no expansion and contraction deformation. Select any unit length of the track slab for stress analysis. As Figure 3 shown, establish the following equilibrium equation:

[0045] σ t t t -σ t t t -dσ t t t -τ(x)dx = 0 (3)

[0046] where σ t represents the stress of the track slab, t t represents the thickness of the track slab, and τ(x) represents the interfacial shear stress. Further, Equation (4) can be obtained from Equation (3):

[0047]

[0048] For the track slab, its elastic state stress satisfies Hooke's law:

[0049]

[0050] where E t represents the elastic modulus of the track slab, and u t represents the longitudinal deformation displacement of the track slab.

[0051] The relative displacement s between the track slab and the weak interface of the filling layer is expressed as:

[0052] s = u t -u c (6)

[0053] where u cRepresents the overall longitudinal displacement of the filling layer and the base plate. Since the base plate is a longitudinally continuous seamless structure, it can be assumed that u c = 0, then s = u t .

[0054] According to equations (5) and (6), we can obtain:

[0055]

[0056] According to equations (7) and (4), we can obtain:

[0057]

[0058] It can be seen from equation (2) that the interfacial shear stress τ can be expressed as a function of the relative displacement s. According to equations (2) and (8), we have:

[0059]

[0060] Under the action of uniform temperature rise and fall, the two ends of the track slab undergo telescopic displacement. The interfacial stress at the end position of the track slab is the largest. Due to the structural symmetry, the relative displacement of the track slab - filling layer interface at the longitudinal middle position of the track slab is 0, and the interfacial shear stress is 0. Therefore, there must be an elastic state (I) near the middle position of the track slab interface. The magnitude of the interfacial shear stress at the end of the track slab is related to the temperature drop amplitude. The end telescopic displacement increases with the increase of the temperature drop amplitude, and the corresponding interfacial shear stress at the end theoretically gradually develops from the elastic state to the slip state (Ⅲ). The shear damage evolution of the track slab can be divided into three stages: the fully elastic stage, the elastic - damage stage, and the elastic - damage - slip stage.

[0061] (1) Fully elastic stage

[0062] In this stage, the entire interface is in the elastic state I, as shown in (a) of Figure 4 . According to equations (2) and (9), we can obtain equation (10):

[0063]

[0064] Let Then the basic equilibrium equation (10) can be written as equation (11):

[0065]

[0066] The general solution of equation (11) can be expressed as:

[0067]

[0068] From equation (7) and equation (12), the stress distribution of the track slab cross - section in the elastic stage is shown in equation (13):

[0069]

[0070] Based on Figure 4 the coordinate shown in (a) of, establish the boundary conditions of the equation at this stage:

[0071]

[0072] In equation (14), P = EαΔT×(bt t ), representing the equivalent temperature drop load at the plate end. According to Figure 4 the reference coordinate axis shown, in the formula, L is half of the longitudinal length of the track slab. Based on the above boundary conditions, the analytical solutions of equations (12) and (13) can be obtained:

[0073]

[0074] Substitute equation (15) into equations (13), (12), and (8) respectively, and the stress, deformation displacement, and interface shear stress distributions of the track slab cross-section at this stage can be obtained. The results are shown in equation set (16):

[0075]

[0076] It can be seen from equation (16) that τ(x) is distributed in a parabola along the length direction of the track slab, and the interface shear stress near the plate end is the largest. When x = L, τ(L) = τ u reaches the limit state of the fully elastic stage. At this time, the equivalent temperature drop load P and the equivalent overall temperature drop amplitude ΔT at the plate end can be deduced according to equation (16) as shown in equation (17):

[0077]

[0078] In equation (17), α represents the linear expansion coefficient of the track slab material, and b represents the width of the track slab.

[0079] (2) Elastic-damage stage

[0080] In this stage, the interface near the longitudinal center position of the track slab is in the elastic state I, and the interface within a certain range near the plate end is in the damage state II. Assume that the length of the interface in the elastic state is a, then the length of the interface in the damage state is L - a, as shown in Figure 4 (b) of. According to equations (14) and (15), the governing equations at this stage can be expressed by equations (18) and (19):

[0081]

[0082] When a ≤ x ≤ L, the general solution of the equation can be expressed as:

[0083]

[0084] Establish Equation (21) according to the boundary conditions of x = a and the free end x = L:

[0085]

[0086] Based on the boundary conditions shown in Equation (21), the analytical solution of Equation (22) can be obtained:

[0087]

[0088] Substitute Equation (22) into Equation (20) respectively, and based on Equations (7) and (8), the analytical formulas for the cross-sectional stress, deformation displacement, and interfacial shear stress of the track slab when a ≤ x ≤ L can be derived as shown in Equation Set (23):

[0089]

[0090] Integrating the full interfacial shear stress can establish the equilibrium equation (24). When the equivalent load P = EαΔT×(bt t ) is determined, the elastic state interfacial length a can be obtained by iteration from Equation (24), and the interfacial length corresponding to the damage stage is equal to L - a.

[0091]

[0092] When x = L, τ(L) = τ f The interface reaches the critical state of the elastic-damage stage. At this time, the interfacial shear stress satisfies Equation (25).

[0093]

[0094] Based on Equation (16), the state variables of the track slab and the interfacial shear stress in the range of 0 ≤ x ≤ a at this stage can be obtained, as shown in Equation Set (26).

[0095]

[0096] (3) Elastic-damage-slip stage

[0097] As Figure 4 shown in (c), in this stage, the interface near the center of the track slab is still in the elastic state I, the interface near the slab end is in the slip state III, and the remaining interfaces are in the damage state II. Assume that the interfacial length in the slip state is d, and the interfacial length in the damage state is L - d - a. In this stage, the elastic state interface (0 ≤ x ≤ a) satisfies Equation (26), the damage state interface (a ≤ x ≤ L - d) satisfies Equation (23), and the shear stress and displacement state at any position of the slip state interface (L - d ≤ x ≤ L) can be expressed by Equation (27):

[0098]

[0099] According to Equation (23), when x = L - d, the expression of the interfacial shear stress can be written as Equation (28), which can quantitatively characterize the dependence relationship between the slip interface length d (d < L) and the elastic interface length a at this stage.

[0100]

[0101] According to Equation (23) and Equation (27), the quantitative relationship formula (29) between the equivalent load (temperature) at the end of the x = L plate and the interfacial state variables can be obtained.

[0102]

[0103] In summary, according to Equations (16), (23), (26), and (27), the shear damage state of the weak interface between the track slab and the filling layer under any temperature drop amplitude can be evaluated, and the influence mechanisms of the structural parameters of the track slab (longitudinal length L, width b, thickness t t , elastic modulus E t ) and the interfacial characteristic parameters (s u , s f , τ u , τ f ) on the evolution of the interfacial damage state can be quantitatively analyzed.

[0104] Taking the commonly used longitudinally connected precast slab ballastless track system (CRTS II) for high-speed railways as an example, the implementation steps of the method of the present invention will be described in detail with reference to the accompanying drawings:

[0105] Step 1: Obtain the constitutive relationship between the shear stress and slip of the weak interface

[0106] Carry out on-site shear push plate tests on the 1:1 physical structure. Among them, the ballastless track system (track slab, base slab) is fabricated, installed, and positioned according to the actual structural system composition and dimensions. The interface filling layer is poured using the same raw materials, formulations, mixing, and pouring processes as on-site.

[0107] After curing to meet the standard requirements according to the actual construction specifications, a push plate test is carried out. The test loading system consists of a reaction wall and a synchronous hydraulic jacking system, which is used to apply a uniform and synchronous longitudinal thrust to the end of the plate. The monitoring system consists of a pressure sensor, a displacement sensor, and a data acquisition instrument, which is used to monitor the curve of the corresponding relationship between the longitudinal thrust and the displacement. Repeat multiple groups of push plate experiments to ensure the reliability of the test results. The longitudinal thrust-displacement relationship curve is obtained from the test, and the parameters of the shear stress-slip three-line constitutive model are determined according to Formula (1) and Figure 2 as shown in Table 1:

[0108] Table 1

[0109]

[0110] Step 2: Establish and solve the analytical equation for shear damage evolution. The statistical results of the main parameters of this type of ballastless track structure are shown in Table 2.

[0111] Table 2

[0112]

[0113] (1) Elastic stage

[0114] According to Equation (17), substituting the relevant parameters in Tables 1 and 2, the critical equivalent load and equivalent temperature drop amplitude in this stage are 1448.0 kN and 7.28 °C respectively. To verify the accuracy of the analytical results in this stage, according to Equation (16), the interface shear stress distributions at the limit state (-7.28 °C) and when the temperature drops by -5 °C in this stage are solved respectively, and compared with the finite element numerical simulation results as Figure 5 shown in (a) of Figure, the two are in good agreement. The statistical results of the maximum and minimum errors are shown in Table 3, and the maximum relative error is only 1.20%.

[0115] When -7.28 °C ≤ ΔT < 0 °C, the weak interface between the track slab and the mortar layer is completely in the elastic state. According to Equation (17), the relationship curve between the maximum shear stress τ(x = L) at the slab end interface and the equivalent temperature drop amplitude ΔT can be obtained, as Figure 6 shown in (a) of Figure. In the elastic stage, the maximum shear stress at the slab end interface is proportional to the equivalent temperature drop amplitude. When the temperature drop amplitude reaches 7.28 °C, the maximum shear stress at the slab end interface reaches the interface shear strength. As the temperature continues to drop, the slab end interface will enter the damage degradation state first.

[0116] (2) Elastic-damage stage

[0117] According to Equations (24) and (25), the interface state variables and critical equivalent load corresponding to the limit state (x = L, τ(L) = τ f ) in the elastic-damage stage are obtained. Substituting the relevant parameters, the lengths of the elastic interface and the damaged interface corresponding to the limit state in the elastic-damage stage are 620.6 mm and 2604.4 mm respectively, and the critical equivalent load and equivalent temperature drop amplitude are 7431.7 kN and -37.35 °C respectively, indicating that when the temperature drop amplitude exceeds 37.35 °C, the interface will evolve from the elastic-damage state to the elastic-damage-slip state. The analytical solutions of the -37.35 °C and -18.16 °C working conditions are compared with the calculation results of the finite element model as Figure 5 shown in (b) of Figure, the two are in good agreement. The statistical results of the maximum and minimum errors are shown in Table 3, and the maximum relative error is only 2.30%, which proves the accuracy of the interface damage analytical solution in this stage.

[0118] When -37.35°C ≤ ΔT < -7.28°C, according to equations (24) and (25), the quantitative relationship curves of the elastic state interface length a, the damaged state cross-section length L - a, and the equivalent temperature drop ΔT in this stage can be obtained. As shown in Figure 6 (b) of Figure 6 , when the temperature drop reaches 37.35°C, the shear stress at the plate end interface drops to 5.65 kPa, reaching the critical state of damage-slip. As the temperature further decreases, the shear failure will occur first at the plate end interface, and frictional slip will occur.

[0119] (3) Elastic-damage-slip stage

[0120] According to equation (28) and formula (29), for any given slip interface length d (d < L), the corresponding elastic interface length a and equivalent load (temperature) can be obtained. When the slip interface length reaches 600 mm, the elastic interface length and equivalent temperature drop at this time are 504.4 mm and -45.8°C respectively. When the given slip interface length is 1200 mm, the corresponding elastic interface length and equivalent temperature drop are 388.7 mm and -51.9°C respectively. To verify the accuracy of the analytical solution in this stage, the temperature drop conditions of the track slab in the finite element numerical model are set to -45.8°C and -51.9°C respectively, and the comparison of the interface shear stress results is as shown in Figure 5 (c) of Figure 5 . The analytical solution is in good agreement with the numerical solution. The statistical results of the relevant maximum errors are shown in Table 3, which verifies the accuracy of the analytical solution of the interface damage in this stage.

[0121] When ΔT < -37.35°C, the slip will occur first at the plate end interface. According to equations (28) and (29), the quantitative relationship curves of the slip state interface length d, the elastic state interface length a, and the damaged state cross-section length L - d - a and the equivalent temperature drop ΔT in this stage can be obtained. As shown in Figure 6 (c) of Figure 6 , this figure can intuitively reflect the dynamic evolution process of the weak interface between the track slab and the mortar layer during the elastic-damage-slip stage with the change of temperature drop.

[0122] Table 3

[0123]

[0124] The results show that the method described in the present invention can effectively characterize the shear stress distribution and damage state of the weak interface between the track slab and the filling layer in different stages, and clearly clarify the whole process of shear damage evolution of the weak interface between the precast track slab and the filling layer. Compared with the numerical simulation method, the method described in the present invention can characterize the precise quantitative relationship between the shear stress distribution of the weak interface between the track slab and the filling layer and the temperature drop, avoiding the complexity and time consumption of model establishment and update in the numerical simulation method, and having many advantages such as clear mechanism, high solution efficiency, and convenient parameter discussion. The present invention is also applicable to other types of track slab systems with connection interface layers.

[0125] The present invention discloses a method for evaluating the shear damage evolution of the weak interface between the track slab and the filling layer under temperature drop, which accurately and efficiently analyzes the law of shear damage degradation of the interface and the influence mechanism of related factors, evaluates the shear damage state of the weak interface between the precast track slab and the filling layer of high-speed railway under any temperature drop amplitude, overcomes the restriction that the relative slip of the internal interface is difficult to accurately measure in the actual service environment, avoids a large number of numerical simulation trials, provides a theoretical reference for the optimization of track slab design and maintenance plans, and has good application prospects.

[0126] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for evaluating the shear damage evolution of the weak interface between the track slab and the filling layer under the action of cooling, characterized in that Including: Obtain the shear stress-slip constitutive relationship of the weak interface between the track slab and the filling layer through the push plate test; According to the temperature drop and shrinkage deformation characteristics of the track slab, divide the interface shear damage evolution into a fully elastic stage, an elastic-damage stage, and an elastic-damage-slip stage; Based on the above shear stress-slip constitutive relationship and damage stage division, establish the corresponding mechanical differential equations for each stage and solve them to obtain the analytical solution of the interface shear stress distribution; Analyze the influence laws of the track slab structure parameters and interface constitutive parameters on the shear damage evolution through the above analytical solution.

2. The method for evaluating the shear damage evolution of the weak interface between the track slab and the filling layer under the cooling effect as described in claim 1, wherein The push plate test includes: Apply a longitudinal thrust to the specimen including the track slab, filling layer and base slab, and monitor the curve of the thrust and displacement; Determine the ultimate shear resistance, residual frictional resistance and the corresponding slip amount of the interface according to the curve, and establish a shear stress-slip three-line constitutive model.

3. The shear damage evolution evaluation method for the weak interface between the track slab and the filling layer under the cooling effect as described in claim 1, characterized in that, The mechanical differential equation of the fully elastic stage is established based on the linear relationship between the shear stress and slip amount in the elastic stage, and the hyperbolic function analytical solutions of the cross-sectional stress of the track slab and the interface shear stress distribution are obtained by solving.

4. The method for evaluating the shear damage evolution of the weak interface between the track slab and the filling layer under the cooling effect according to claim 1, characterized in that, The mechanical differential equation of the elastic-damage stage includes: Establish the interface mechanical differential equations of the elastic region and the damage region respectively based on the shear stress-slip three-line constitutive relationship; Solve the corresponding interface shear stress analytical equations of the elastic region and the damage region through the boundary conditions of the elastic region and the damage region respectively; Establish the integral sum of the full interface shear stress and the external load balance equation, and iteratively solve according to the external load to obtain the length of the elastic region and the shear stress distribution of the damage region.

5. The method for evaluating the shear damage evolution of the weak interface between the track slab and the filling layer under the cooling effect according to claim 1, characterized in that, The mechanical differential equation of the elastic-damage-slip stage includes: Set the interface shear stress as a constant value of the residual frictional resistance in the slip region; Establish a balance equation through the continuity boundary conditions of the slip region and the damage region, and solve the quantitative relationship between the length of the slip region and the temperature drop amplitude.

6. The method for evaluating the shear damage evolution of the weak interface between the track slab and the filling layer under temperature drop according to claim 1, characterized in that The track slab structure parameters include the length, width, thickness and elastic modulus of the track slab; The interface constitutive parameters include the ultimate shear stress, residual frictional resistance and the corresponding critical slip amount.

7. The method for evaluating the shear damage evolution of the weak interface between the track slab and the filling layer under the cooling effect according to claim 1, characterized in that, The critical equivalent temperature drop amplitude in the fully elastic stage is obtained by back-calculating through the analytical solution in the elastic stage, specifically: based on the condition that the maximum shear stress in the elastic region is equal to the interface ultimate shear strength, calculate the corresponding critical equivalent load and equivalent temperature drop amplitude.

8. The method for evaluating the shear damage evolution of the weak interface between the track slab and the filling layer under the cooling effect according to claim 1, wherein, The interface region lengths in different stages are determined by iterative calculation through the integral balance equation of the full interface shear stress, and the process includes: establishing the integral sum of the full interface shear stress and the external load balance equation, and iteratively solving according to the external load to obtain the interface region lengths and interface shear stress distributions in different stages.

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