Loading device for simulating dynamic vehicle bogie load to dynamic effect of ballastless track subgrade

Abstract

The application provides a loading device for simulating the load of a motor vehicle bogie on a ballastless track subgrade, and relates to the technical field of railway subgrade dynamic performance evaluation, which comprises a loading plate, a vibrating platform, accessories and a servo vibrating motor control system. Four pads corresponding to the positions of the wheels of a double-axle bogie transmit the exciting force generated by the eccentric block to the loading plate, which has the same cross-sectional bending stiffness as the ballastless track structure and the same width as the base plate, and the load distribution on the surface of the subgrade is similar to that of a real vehicle on a real road. The maximum self-weight of the vibrating platform is not less than half of the peak value of the motor vehicle bogie dynamic load to be simulated, and the maximum dynamic load amplitude that the servo vibrating motor can output under the condition of the maximum counterweight is not less than the self-weight of the vibrating platform. The application solves the problems of abrasion, vibration and noise caused by the reverse direction and in-phase synchronous rotation of the vibrating motor realized by the traditional mechanical connection, high manufacturing and maintenance costs, and a complex cooling system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of railway subgrade dynamic performance evaluation, and particularly relates to a loading device for simulating the dynamic effect of a motor train unit bogie load on a ballastless track subgrade. BACKGROUND

[0002] A railway subgrade is a geotechnical structure that supports a track structure and the upper train load, and is mainly composed of soil and stone bulk materials. Due to the porous nature of soil and stone, the subgrade structure has relatively weak resistance to deformation. In particular, the subgrade bed directly in contact with the track structure is prone to cumulative deformation under long-term train cyclic load, showing failure and damage characteristics, which affects the safe operation of the line. The adaptability of the ballastless track structure to the subgrade deformation is low, and it is particularly necessary to control the cumulative deformation of the subgrade soil body during the operation stage. Therefore, before the subgrade is completed and the track is laid, it is important to use a loading device simulating the dynamic effect of a train to carry out dynamic response and accelerated fatigue tests, obtain subgrade dynamic parameters, and evaluate the subgrade cumulative deformation resistance, which is crucial to engineering construction.

[0003] The loading device for field subgrade dynamic testing mainly uses an inertial exciter to generate a harmonic force to excite a large mass counterweight to do vertical vibration and output load to the ground. The load valley value is used to simulate the self-weight of the track structure, and the peak-to-valley value is used to simulate the train load effect. The existing inertial loading device installs a gear or other mechanical connecting member between the rotating shafts of the eccentric blocks to ensure that the eccentric blocks in the exciter rotate in opposite directions and in the same phase synchronously, thereby stabilizing the output vertical excitation force. However, the connecting member between the rotating shafts of the eccentric blocks is mechanically worn and torn during use, and the connecting member needs to be equipped with a cooling system, which leads to a complex structure of the exciter, a large volume, high manufacturing, maintenance and repair costs, and large environmental vibration and noise. In addition, the existing inertial loading device mainly uses a rigid foundation to transfer the load to the subgrade surface, so the distribution of the vibration stress borne by the subgrade is quite different from that of the actual subgrade under the track structure condition, and the response of the dynamic system composed of the loading device and the subgrade structure cannot reflect the true performance of the subgrade structure. Therefore, it is necessary to explore a new type of railway subgrade cyclic loading device to overcome the above-mentioned deficiencies. SUMMARY

[0004] In view of the above-mentioned deficiencies in the prior art, the loading device for simulating the dynamic effect of a motor train unit bogie load on a ballastless track subgrade provided by the present application solves the problems of abrasion, vibration, noise, high manufacturing and repair costs, and complex cooling system caused by the reverse direction and same phase synchronous rotation of the vibration motor achieved by traditional mechanical connection. At the same time, by reasonably setting the key parameters of the loading device, the load amplitude and distribution form output to the subgrade surface are also simulated to be similar to those of a real train on a real road.

[0005] In order to achieve the above object, the technical scheme adopted by the present application is as follows: a loading device for simulating the dynamic effect of a motor train bogie load on a ballastless track subgrade, comprising a loading plate cast on a flat subgrade surface, a vibrating platform located on the loading plate, fittings connected with the vibrating platform, and a servo vibrating motor control system connected with the vibrating platform.

[0006] The present application has the following beneficial effects:

[0007] (1) The loading device for simulating the dynamic effect of a motor train bogie load on a ballastless track subgrade provided by the present application forcibly drives the eccentric blocks to rotate in the opposite direction and in the same phase in a wide frequency range through a servo vibrating motor controller, thereby generating stable vertical excitation force. The vibrating motor with the eccentric blocks does not need to be equipped with gear, chain, belt and other shaft mechanical connecting members, and a cooling system for cooling the gear and other mechanical connecting members. The device has simple and compact structure, small mechanical wear of components, low manufacturing, maintenance and repair costs, and small environmental vibration noise. At the same time, compared with the gear and other mechanical connecting members equipped between the shafts with the eccentric blocks, the eccentric blocks controlled by the servo control system have better reliability in the opposite direction and in the same phase under high-frequency rotation conditions, which is conducive to outputting stable high-frequency vertical excitation force, and the device is safer and more durable.

[0008] (2) The loading device for simulating the dynamic effect of a motor train bogie load on a ballastless track subgrade provided by the present application has the same load distribution form as that generated by the actual operating train bogie on the subgrade surface under the ballastless track structure, so that the dynamic response of the subgrade-loading device system can more truly reflect the dynamic performance of the ballastless track subgrade structure.

[0009] Further, the loading plate is a reinforced concrete plate in the shape of a cuboid;

[0010] The width of the reinforced concrete plate is the same as the ballastless track supporting layer or base plate to be simulated, the cross-sectional bending stiffness of the reinforced concrete plate is consistent with the ballastless track structure, and the length of the reinforced concrete plate is not less than the longitudinal distribution range of the subgrade surface dynamic stress caused by the motor train bogie load.

[0011] The beneficial effect of the above further scheme is that the loading plate provided by the present application has a contact relationship with the subgrade, and can achieve the technical effect of approximating the interaction characteristics of the simulated ballastless track structure and the subgrade.

[0012] Still further, the vibrating platform comprises a vibrating platform bottom plate, a plurality of counterweight blocks located on the vibrating platform bottom plate, two servo vibrating motors with the same parameters, and a plurality of groups of eccentric blocks installed on both ends of the rotating shaft of the servo vibrating motor, and the servo vibrating motor is connected with the servo vibrating motor control system.

[0013] The vibration platform bottom plate is a reinforced concrete plate, a servo vibration motor mounting bolt is embedded in the middle of the vibration platform bottom plate, and first reserved holes are arranged on the two sides of the vibration platform bottom plate.

[0014] Each of the counterweights is a reinforced concrete plate, and a plurality of counterweights are symmetrically arranged on the two sides of the vibration platform bottom plate, and second reserved holes arranged on each side of the counterweight are vertically aligned with the first reserved holes.

[0015] Two servo vibration motors are symmetrically arranged in the middle of the vibration platform bottom plate and are fixedly connected through the servo vibration motor mounting bolt embedded in the middle of the vibration platform bottom plate, and four groups of eccentric blocks are uniformly arranged on the four ends of the rotating shafts of the two servo vibration motors, and the mass and eccentric radius of the eccentric blocks are adjustable.

[0016] The beneficial effect of the further scheme is that the vibration platform mass, the vibration motor eccentric block mass and the eccentric radius adjustment provided by the application can realize the technical effect that the load amplitude output by the vibration system is the same as the simulated motor bogie load.

[0017] Further, the vibration platform mass is adjusted by increasing or decreasing the number of counterweights, and the maximum self-weight (M max ×g) is not less than 0.5 times the peak value of the motor bogie dynamic load, wherein M max represents the maximum mass of the vibration platform, and g represents the acceleration of gravity.

[0018] The beneficial effect of the further scheme is that the loading device for simulating the dynamic load of the motor bogie on the subgrade of the ballastless track provided by the application requires that the maximum self-weight of the vibration platform is not less than half of the peak value of the motor bogie dynamic load to be simulated, so as to avoid that the performance of the device is limited due to insufficient vibration platform mass.

[0019] Further, the accessories include four vibration platform pads, eight connecting screw rods, and nuts and washers.

[0020] Each of the vibration platform pads is arranged above the loading plate, the positions of the vibration platform pads correspond to the four wheel load action points of the motor bogie, the vibration platform bottom plate is horizontally placed on the vibration platform pads, the center of the vibration platform bottom plate is vertically aligned with the intersection points of the diagonal lines of the four vibration platform pads and is in uniform contact with the four vibration platform pads, and the center cross section of each side of the counterweight is in the same vertical plane as the vibration platform pad on the corresponding side.

[0021] The eight connecting screw rods pass through the first reserved holes of the vibration platform bottom plate and the second reserved holes of the counterweights respectively, and the washers and nuts are arranged at the two ends of the connecting screw rods to connect the vibration platform bottom plate and the counterweights.

[0022] The beneficial effect of the further scheme is that the vibration platform cushion block and connecting bolt provided by the application can realize the technical effect that the load action point position of the vibration platform output is consistent with the simulated motor bogie load, and the vibration platform bottom plate and the counterweight block are connected as a whole to ensure stable and safe operation of the vibration platform.

[0023] Further, the servo vibration motor control system comprises a servo vibration motor controller and a connecting line.

[0024] The servo vibration motor controller is connected with the servo vibration motor through the connecting line, controls the rotating speed of the servo vibration motor, ensures that the two servo vibration motors rotate in opposite directions and in the same phase, and generates stable vertical exciting force.

[0025] The beneficial effect of the further scheme is that the servo vibration motor control system provided by the application can realize the technical effect that the two vibration motors drive the eccentric blocks to rotate in opposite directions and in the same phase in a wide frequency range, and generate stable vertical exciting force.

[0026] Further, the selection of the servo vibration motor comprises the following steps:

[0027] S1, measuring the maximum mass M of the vibration platform max , and determining the minimum natural frequency f of the vibration system according to the vertical stiffness coefficient K provided by the roadbed, the loading plate and the vibration platform cushion block n,min ;

[0028] S2, obtaining the maximum exciting force F and the maximum rotating angular frequency ω generated by the selected servo vibration motor, and determining the eccentric block parameters matched with the single servo vibration motor, i.e. the maximum value (m·r) of the product of the eccentric block mass m and the eccentric radius r max ;

[0029] S3, measuring the vertical damping coefficient C provided by the roadbed, the loading plate and the vibration platform cushion block to the vibration platform, and determining the dynamic load amplitude F' output by the vibration platform under the condition that the maximum value (m·r) max and the minimum natural frequency f n,min ;

[0030] S4, judging whether the dynamic load amplitude F' output by the vibration platform under the excitation of the servo vibration motor is not less than the requirement of the maximum self-weight (M max ×g) of the vibration platform, if yes, the selection process is completed, otherwise, a servo vibration motor capable of outputting greater exciting force F is selected again, and the step S2 is returned until the requirement is met.

[0031] The beneficial effect of the further scheme is that the servo vibration motor provided by the application considers the comprehensive influence of vibration platform mass, support stiffness and damping, output load amplitude and other factors on the output load of the vibration platform and the dynamic amplification effect, avoids the selection of a vibration motor with insufficient excitation force output capacity, and can realize the technical effect of reasonable selection of a vibration motor under the load amplitude simulation of a motor bogie.

[0032] Further, the power load amplitude F' output by the vibration platform is expressed as follows:

[0033]

[0034] (m·r) max =F / ω 2

[0035]

[0036] The beneficial effect of the further scheme is that the vibration platform output load amplitude expression provided by the application clearly defines the functional relationship of vibration platform mass, support stiffness and damping, maximum excitation force of the vibration motor and rotational angular frequency, and can realize the technical effect of fine control of key parameters of the loading device. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The loading device is used for simulating the dynamic action of the load of a motor bogie on a ballastless track subgrade.

[0038] Figure 2 The figure is a servo vibration motor selection flowchart.

[0039] Figure 3 The figure is a schematic diagram of the relationship between the output load amplitude of the vibration platform and the self-weight under different excitation frequencies.

[0040] Among them, 1 is a loading plate, 101 is a reinforced concrete plate, 2 is a vibration platform, 201 is a vibration platform bottom plate, 202 is a counterweight, 203 is a servo vibration motor, 204 is an eccentric block, 205 is a first reserved hole, 206 is a servo vibration motor mounting bolt, 3 is a fitting, 301 is a vibration platform cushion block, 302 is a connecting screw, 303 is a nut, 304 is a gasket, 4 is a servo vibration motor control system, 401 is a servo vibration motor controller, and 402 is a connecting line. DETAILED DESCRIPTION

[0041] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0042] Example 1

[0043] like Figure 1 As shown, the present invention provides a loading device for simulating the dynamic effect of a motor vehicle bogie load on a ballastless track subgrade, comprising a loading plate 1 cast in situ on a flat subgrade surface, a vibration platform 2 located on the loading plate 1, an accessory 3 connected to the vibration platform 2, and a servo vibration motor control system 4 connected to the vibration platform 2.

[0044] In this embodiment, the loading plate 1 is a rectangular reinforced concrete slab 101; the width of the reinforced concrete slab 101 is the same as the supporting layer or base plate of the ballastless track to be simulated, the cross-sectional bending stiffness of the reinforced concrete slab 101 is consistent with the ballastless track structure, and the length of the reinforced concrete slab 101 is not less than the longitudinal distribution range of the dynamic stress on the roadbed surface caused by the EMU bogie load.

[0045] In this embodiment, the vibration platform 2 includes a vibration platform base plate 201, a plurality of counterweights 202 (8 counterweights 202) respectively located on the vibration platform base plate 201, two servo vibration motors 203 with the same parameters (2 servo vibration motors 203) and multiple eccentric blocks 204 (4 groups of eccentric blocks 204) installed at both ends of the rotating shaft of the servo vibration motor 203. The servo vibration motor 203 is connected to the servo vibration motor control system 4; the vibration platform base plate 201 is a reinforced concrete slab, and a servo vibration motor mounting bolt 206 is pre-embedded in the middle of the vibration platform base plate 201. A first reserved hole 205 is provided on both sides of the vibration platform base plate 201; each counterweight is provided. The weight blocks 202 are all reinforced concrete slabs, and multiple counterweight blocks 202 are symmetrically installed on both sides of the vibration platform base plate 201. The central cross-section of the counterweight block 202 on each side is in the same vertical plane as the vibration platform pad 301 on the corresponding side, and the second reserved hole set on each side of the counterweight block 202 is vertically aligned with the first reserved hole 205; two servo vibration motors 203 are symmetrically installed in the middle of the vibration platform base plate 201, and are fixedly connected by the servo vibration motor mounting bolts 206 embedded in the middle of the vibration platform base plate 201; four groups of eccentric blocks 204 are evenly installed at the four ends of the rotating shafts of the two servo vibration motors 203, and the mass and eccentric radius of the eccentric blocks 204 are adjustable.

[0046] In this embodiment, the mass of the vibration platform 2 is adjusted by increasing or decreasing the number of counterweight blocks 202. The maximum deadweight (Mmax Xg) not less than 0.5 times the peak value of the bogie dynamic load, wherein, M max represents the maximum mass of the vibration platform 2, and g represents the acceleration of gravity.

[0047] In this embodiment, the accessory 3 includes 4 vibration platform pads 301, 8 connecting screws 302, and nuts 303 and washers 304; each vibration platform pad 301 is placed above the loading plate 1, the position of each vibration platform pad 301 corresponds to the 4 wheel load points of the bogie, the vibration platform bottom plate 201 is placed on the vibration platform pad 301, the center of the vibration platform bottom plate 201 is vertically aligned with the diagonal intersection points of the 4 vibration platform pads 301, and is in uniform contact with the 4 vibration platform pads 301; 8 connecting screws 302 pass through the first reserved holes 205 of the vibration platform bottom plate 201 and the second reserved holes of the counterweight block 202, and the washers 304 and nuts 303 are installed at both ends of the connecting screws 302 to connect the vibration platform bottom plate 201 and the counterweight block 202.

[0048] In this embodiment, the servo vibration motor control system 4 includes a servo vibration motor controller 401 and a connecting line 402; the servo vibration motor controller 401 is connected with the servo vibration motor 203 through the connecting line 402, controls the rotating speed of the servo vibration motor 203, ensures that the two servo vibration motors 203 rotate in opposite directions and in the same phase, generates a stable vertical excitation force, and realizes the same phase and opposite direction synchronous rotation under different rotating speeds to generate a stable vertical excitation force.

[0049] In this embodiment, as shown in Figure 2 , the selection of the servo vibration motor 203 includes the following steps:

[0050] S1, measure the maximum mass M max of the vibration platform 2 and the vertical stiffness coefficient K provided by the roadbed, the loading plate 1 and the vibration platform pad 301 to the vibration platform 2, and determine the minimum natural frequency f n,min of the vibration system:

[0051]

[0052] S2, obtain the maximum excitation force F and the maximum rotating angular frequency ω that the servo vibration motor 203 to be selected can generate, and determine the eccentric block 204 parameters matched with a single servo vibration motor 203, that is, the maximum value (m·r) max of the product of the mass m and the eccentric radius r of the eccentric block 204:

[0053] (m·r) max = F / ω 2

[0054] S3, measure the vertical damping coefficient C provided to the vibration platform 2 by the roadbed, loading plate 1 and vibration platform pad 301, and determine the maximum value (m·r) of the servo vibration motor 203. max and the minimum natural frequency f n,min Under these conditions, the dynamic load amplitude F' output by vibration platform 2 is:

[0055]

[0056] S4, determine whether the dynamic load amplitude F' output by the vibration platform 2 under the excitation of the servo vibration motor 203 is not less than the maximum deadweight (M max ×g) requirement, if so, the selection process is completed, otherwise, reselect the servo vibration motor 203 that can output a larger exciting force F, and return to step S2 until the requirements are met.

[0057] In summary, the loading device provided by the present invention has a simple structure, compact size, low manufacturing and operating costs, and low environmental vibration and noise. The system vibration formed with the roadbed can truly reflect the dynamic characteristics of the ballastless track roadbed structure, which is of great significance for improving the evaluation of the dynamic performance of railway roadbeds.

[0058] Example 2

[0059] One design for loading plate 1 was determined: a reinforced concrete loading plate 101 with a length of 10.0 m, a width of 3.1 m, and a height of 0.35 m. When conducting subgrade structural dynamic performance tests at consecutive locations on the ballastless track base plate, vibration platform pads 301 were placed in the center of loading plate 1, with a horizontal spacing of 1.5 mm and a vertical spacing of 2.5 m.

[0060] A vibration platform base plate 201 is determined to be 4.2m long, 1.8m wide, and 0.5m high. A counterweight block 202 is determined to be 1.5m long, 2.0m wide, and 0.2m high. The concrete weight is 24kN / m 3 The vibration platform base plate 201 has a deadweight of 90.72 kN, and each counterweight has a deadweight of 14.4 kN.

[0061] 0, 2, 4, 6, and 8 counterweights are symmetrically installed on both sides of the servo vibration motor 203 on the vibration platform base plate 201. Ignoring the weight of the servo vibration motor 203, the weight G of the vibration platform 2 is 90.72kN, 119.52kN, 148.32kN, 177.12kN, and 205.92kN respectively.

[0062] Vibration platform 2 maximum deadweight G max (i.e. M max ×g) is about 205.92kN, and the maximum peak dynamic load of the bogie that can be used for simulation is 411.84kN.

[0063] The following press Figure 2 Follow the steps below to select a servo vibration motor:

[0064] Step S1: Take the stiffness coefficient K = 850MN / m provided by the roadbed, loading plate 1 and vibration platform pad 301 to the vertical constraint of the vibration platform 2, and estimate the minimum natural frequency f of the vibration system n,min =32.34Hz.

[0065] Step S2: The maximum exciting force F that the servo vibration motor 203 can generate is selected to be 50 kN, the maximum rotation speed is about 3000 rpm, the corresponding maximum rotation angular frequency ω is 314.16 rad / s, and the maximum value of the product of the eccentric mass m and the eccentric radius r (m·r) is selected to be max =0.51kg·m.

[0066] Step S3: Take the damping coefficient C = 830 kN·s·m provided by the roadbed, loading plate 1 and vibration platform pad 301 to the vertical constraint of the vibration platform 2 -1 , the eccentric mass (202) is at a frequency f n,min During rotation, the vibration platform 2 outputs a dynamic load with an amplitude of F'=212.26 kN.

[0067] Step S4: The amplitude F' of the dynamic load is greater than the maximum deadweight G of the vibration platform 2. max (i.e. M max ×g) is 3.08% larger, F N =50kN servo vibration motor 203 meets the selection requirements.

[0068] The deadweight G of the vibration platform 2 is 90.72 kN, 119.52 kN, 148.32 kN, 177.12 kN, and 205.92 kN, and m·r=(m·r) max =0.51kg·m, the servo vibration motor 203 drives the eccentric block 204 to rotate at different frequencies f, and the load amplitude F' output by the vibration platform 2 is compared with its own weight G. Figure 3 As shown in the figure. When the frequency f is less than the natural frequency of the system, the load amplitude F' output by the vibration platform 2 increases with the increase of the frequency f. When the frequency f is greater than the natural frequency of the system, the load amplitude F' gradually decreases with the increase of the frequency f. When the frequency f is the resonant frequency that is basically consistent with the natural frequency, the F' value is the largest.

[0069] In addition, Figure 3 It can be seen that when the weight of vibration platform 2 is the largest, the natural frequency of the system is the minimum value f n,min= 32.34 Hz, corresponding to a F' maximum value smaller than the self-weight G in other cases. Therefore, the configuration of the vibration platform 2 with the largest self-weight is selected for the selection of the servo vibration motor 203, so as to match the motor with the load device counterweight as much as possible, and avoid the selected vibration motor from being insufficient in the excitation force output capacity, thereby limiting the performance of the load device. During the use of the load device, attention should be paid to the adjustment of the m r value and the rotating speed of the eccentric block 204, so as to ensure that the load amplitude F output by the vibration platform 2 is not greater than the self-weight G, and to avoid the vibration platform 2 from being separated from the pad 301, thereby causing the load device to overturn and other accidents.

[0070] Those skilled in the art will appreciate that the embodiments described herein are presented for the purpose of helping the reader understand the principles of the present application, and should be understood as not limiting the protection scope of the present application to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations according to the technical inspiration disclosed in the present application without departing from the essence of the present application, and these modifications and combinations are still within the protection scope of the present application.

Claims

1. A loading device for simulating the dynamic effect of a motor vehicle bogie load on a ballastless track subgrade, characterized in that: It comprises a loading plate (1) cast in situ on a flat roadbed surface, a vibration platform (2) located on the loading plate (1), accessories (3) connected to the vibration platform (2), and a servo vibration motor control system (4) connected to the vibration platform (2); The loading plate (1) is a rectangular reinforced concrete plate (101); the width of the reinforced concrete plate (101) is the same as the supporting layer or base plate of the ballastless track to be simulated, the cross-sectional bending stiffness of the reinforced concrete plate (101) is consistent with the ballastless track structure, and the length of the reinforced concrete plate (101) is not less than the longitudinal distribution range of the dynamic stress on the roadbed surface caused by the load of the motor vehicle bogie; The vibration platform (2) comprises a vibration platform base plate (201), a plurality of counterweights (202) respectively located on the vibration platform base plate (201), two servo vibration motors (203) with the same parameters, and a plurality of eccentric blocks (204) installed at both ends of the rotating shaft of the servo vibration motor (203), wherein the servo vibration motor (203) is connected to a servo vibration motor control system (4); the vibration platform base plate (201) is a reinforced concrete plate, a servo vibration motor mounting bolt (206) is pre-buried in the middle of the vibration platform base plate (201), and first reserved holes (204) are provided on both sides of the vibration platform base plate (201) 5); Each of the counterweight blocks (202) is a reinforced concrete slab, and a plurality of counterweight blocks (202) are symmetrically mounted on both sides of the vibration platform base plate (201), and a second reserved hole provided on each side of the counterweight block (202) is vertically aligned with the first reserved hole (205); two servo vibration motors (203) are symmetrically mounted in the middle of the vibration platform base plate (201) and fixedly connected by servo vibration motor mounting bolts (206) pre-buried in the middle of the vibration platform base plate (201); four groups of eccentric blocks (204) are evenly mounted on the four ends of the rotating shafts of the two servo vibration motors (203), and the mass and eccentric radius of the eccentric blocks (204) are adjustable; The accessory (3) includes four vibration platform pads (301), eight connecting screws (302), nuts (303) and gaskets (304); each of the vibration platform pads (301) is placed above the loading plate (1), and the position of each of the vibration platform pads (301) corresponds to the four wheel load action points of the motor vehicle bogie. The vibration platform base plate (201) is placed flat on the vibration platform pads (301), and the center of the vibration platform base plate (201) is vertically aligned with the intersection of the diagonals of the four vibration platform pads (301), and is in uniform contact with the four vibration platform pads (301). The central cross section of the counterweight block (202) on each side is in the same vertical plane as the vibration platform pad (301) on the corresponding side; the eight connecting screws (302) respectively pass through the first reserved hole (205) of the vibration platform base plate (201) and the second reserved hole of the counterweight block (202), and washers (304) and nuts (303) are installed at both ends of the connecting screws (302) to connect the vibration platform base plate (201) and the counterweight block (202).

2. The loading device for simulating the dynamic effect of a motor vehicle bogie load on a ballastless track subgrade according to claim 1, characterized in that: The mass of the vibration platform (2) is adjusted by increasing or decreasing the number of counterweight blocks (202). Not less than 0.5 times the peak value of the dynamic load of the EMU bogie, where: represents the maximum mass of the vibration platform (2), Represents the acceleration due to gravity.

3. The loading device for simulating the dynamic effect of a motor vehicle bogie load on a ballastless track subgrade according to claim 1, characterized in that: The servo vibration motor control system (4) includes a servo vibration motor controller (401) and a connecting line (402); The servo vibration motor controller (401) is connected to the servo vibration motor (203) via a connecting line (402) to control the rotation speed of the servo vibration motor (203) to ensure that the two servo vibration motors (203) rotate synchronously in opposite directions and in the same phase, thereby generating a stable vertical exciting force.

4. The loading device for simulating the dynamic effect of a motor vehicle bogie load on a ballastless track subgrade according to claim 3, characterized in that: The selection of the servo vibration motor (203) includes the following steps: S1. Measure the maximum mass of the vibration platform (2) , and the vertical stiffness coefficient provided to the vibration platform (2) by the roadbed, the loading plate (1) and the vibration platform pad (301) K , determine the minimum natural frequency of the vibration system f n,min ; S2. Obtain the maximum exciting force that can be generated by the selected servo vibration motor (203) F and maximum rotational angular frequency ω , determine the parameters of the eccentric block (204) matched with a single servo vibration motor (203), that is, the mass of the eccentric block (204) m and eccentric radius r The maximum value of the product ( m · r ) max ; S3, measuring the vertical damping coefficient provided to the vibration platform (2) by the roadbed, the loading plate (1) and the vibration platform pad (301) C , determine the servo vibration motor (203) at the maximum value ( m · r ) max and minimum natural frequency f n,min Under the condition, the dynamic load amplitude output by the vibration platform (2) ; S4. Determine the amplitude of the dynamic load output by the vibration platform (2) under the excitation of the servo vibration motor (203) Is it not less than the maximum deadweight of the vibration platform (2)? If yes, then complete the selection process. Otherwise, reselect a model that can output a larger excitation force. F The servo vibration motor (203) is turned on and returns to step S2 until the requirements are met.

5. The loading device for simulating the dynamic effect of a motor vehicle bogie load on a ballastless track subgrade according to claim 4, characterized in that: The dynamic load amplitude output by the vibration platform (2) The expression is as follows: 。

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