Large-span bridge ballastless track deformation rule test method adopting load replacement simulation

Abstract

The invention relates to a large-span bridge ballastless track deformation rule test method adopting load replacement simulation, which comprises the following steps of: after finishing static load by using a water bag, mounting a simulator with a hydraulic cylinder and a push plate on one side of the water bag; the simulators are gradually started through the controller, so that the hydraulic cylinders stretch out until the push plates abut against the water bags till all the push plates on the simulators abut against the water bags; a controller controls a hydraulic pump to push out hydraulic cylinders on all the simulators at the same speed, then the hydraulic cylinders rapidly contract, and after the water bag deviates towards the simulators and makes contact with a push plate, the controller is started to push out the hydraulic cylinders; when the water bag swings according to the set frequency, the dynamic load is measured, after measurement is completed, the hydraulic cylinder is started to enable the push plate and the water bag to make contact with each other and move together, the telescopic speed of the hydraulic cylinder is reduced to enable the water bag to completely stop swinging, and the water bag static load testing device has the advantage that the water bag can be used for static load testing and dynamic load testing.

Description

Technical Field

[0001] The invention relates to the technical field of bridge construction, and in particular to a test method for deformation law of ballastless track of a long-span bridge by using load replacement simulation. Background Art

[0002] Some large-span steel-concrete composite cable-stayed bridges have multi-directional supports and are semi-floating systems. Under the action of temperature and wind loads, the displacement and deformation of the bridge are large and complex. How to study the laws of bridge deformation and displacement so that the linear control during the ballastless track construction process is adapted to the bridge deformation is an important basis for ensuring the high smoothness, high stability and high reliability of the track structure.

[0003] Therefore, in view of the above situation, it is necessary to provide a test method for the deformation law of ballastless track of long-span bridges using load replacement simulation. Summary of the invention

[0004] The purpose of the present invention is to provide a test method for the deformation law of ballastless track of a long-span bridge by using load replacement simulation.

[0005] The object of the present invention is achieved in that: A test method for deformation law of ballastless track of a long-span bridge using load replacement simulation is characterized by comprising the following steps: A. Pour water into the water bag. After using the water bag to complete the static load on the bridge, install a simulator with a hydraulic cylinder and a push plate on one side of the water bag. The hydraulic cylinder is connected to an external controller. B. Arrange pressure sensors on the outer wall of the water bag and at the joints of two adjacent box girders according to the predetermined grids or key points to fully capture the pressure distribution during the shaking of the water bag; at the same time, arrange accelerometers and displacement sensors at key locations such as nodes and supports of the bridge to monitor the dynamic response of the bridge; C. Start the simulator gradually through the controller, so that the hydraulic cylinder extends until the push plate abuts against the water bag, until the push plates on all simulators abut against the water bag; D. Use the controller to control all the hydraulic cylinders on the simulator to push out at the same speed, and then quickly retract. When the water bag deviates toward the simulator and contacts the push plate, start the controller to push out the hydraulic cylinders. E. When the water bag swings at the set frequency, start measuring the dynamic load. After the measurement is completed, start the hydraulic cylinder to make the push plate contact the water bag and move together, and reduce the extension and retraction speed of the hydraulic cylinder so that the water bag stops swinging completely; F. After the experiment, the collected data is preliminarily analyzed. According to the measurement data of the pressure sensor, the pressure distribution of the water bag wall and the end face of the bridge is calculated by interpolating or fitting the pressure values ​​of each pressure sensor; the time domain response curve of the bridge is drawn according to the measurement data of the accelerometer and displacement sensor; the dynamic performance of the bridge can be evaluated by observing the parameters of the vibration frequency, amplitude and displacement of the time domain response curve; the time domain response curve is converted into the frequency domain using fast Fourier transform to obtain a spectrum diagram; the resonance frequency and damping ratio of the bridge can be analyzed through the spectrum diagram to further evaluate the wind resistance of the bridge; G. Compare the experimental results with the theoretical expected values ​​to verify whether the dynamic pressure effect of the simulated wind load and the wind resistance performance of the bridge model meet expectations; the theoretical expected values ​​adopt the numerical water pool method, which uses computer simulation technology to construct a numerical water pool, solves the fluid mechanics equations through numerical methods, and simulates the movement and force of the bridge model under complex wind environments to obtain the theoretical expected values; H. Finally, the relationship between the dynamic load of the water bag, the wind force level, and the bearing time is obtained. Through this relationship, it can be determined what level of wind force the bridge can withstand and how long the load can last.

[0006] As a further illustration of the present invention, preferably, the specifications of the water bag are 1.8m×1.3m×11.5m, and no less than 10 groups of simulators are arranged along the length direction of the water bag.

[0007] As a further illustration of the present invention, preferably, the water bag is filled with 27 t of water liquid to achieve a ballast load of 42 kN / m.

[0008] As a further illustration of the present invention, preferably, after the dynamic load is completed, the expansion bolt pair fixing the simulator on the bridge deck is removed, and the bridge deck is restored to be flat by pouring concrete into the holes.

[0009] As a further illustration of the present invention, preferably, the middle portion of the push plate is a plane, and the left and right sides are arc-shaped surfaces, and the middle plane and part of the arc-shaped surface of the push plate are in contact with the water bag.

[0010] As a further illustration of the present invention, preferably, two groups of hydraulic cylinders are placed in the simulator, a protective telescopic rod is provided between the two groups of hydraulic cylinders, the protective telescopic rod is connected to the controller, and the protective telescopic rod and the hydraulic cylinders do not belong to the same hydraulic system.

[0011] The above technical solution of the present invention has the following advantages: 1. Through the design of the present invention, the water bag can be subjected to static load pressure, and the water bag can be swung laterally through the movement of the mechanical structure composed of the hydraulic cylinder and the push plate. With the swing of multiple water bags at the same frequency, the lateral dynamic load on the bridge and track under different wind forces can be simulated, so that the water bag can be used for both static load test and dynamic load test; 2. The mechanical structure adopts an assembly design, which is convenient for disassembly, transportation and multiple use; 3. During use, the damping of the protective telescopic rod can be used to limit the impact of the water bag on the hydraulic cylinder and extend the service life of the simulator; 4. It has a simple structure and is easy to use. It can greatly improve work efficiency, save a lot of money, and avoid the error of too large a gap between the data of the maximum wind load that can be obtained only through simulation calculation and the actual construction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is the general assembly effect diagram of the present invention; Figure 2 yes Figure 1 A magnified view of middle; Figure 3 is a partial top view of the present invention; In the figure: 1. simulator; 2. hydraulic cylinder; 3. push plate; 4. water bag; 5. protective telescopic rod. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0014] A test method for the deformation law of ballastless track of long-span bridges using load replacement simulation, combined with Figure 1-Figure 3 , including the following steps: A. Use a water bag 4 with a specification of 1.8m×1.3m×11.5m, and pour 27t of water into the water bag 4 to achieve a ballast load of 42kN / m. At this time, the water bag 4 is fully expanded and can perform a static load test on the bridge; after using the water bag 4 to complete the static load test on the bridge, install a simulator 1 with a hydraulic cylinder 2 and a push plate 3 on one side of the water bag 4, and place two groups of hydraulic cylinders 2 connected to external controllers in the simulator 1. A protective telescopic rod 5 is provided between the two groups of hydraulic cylinders 2. The protective telescopic rod 5 and the hydraulic cylinder 2 do not belong to the same hydraulic system, and can provide resistance when controlling the water bag 4 to stop, protecting the hydraulic cylinder 2 from shrinking; arrange no less than 10 groups of simulators 1 along the length direction of the water bag 4, and each group of simulators 1 is fixed to the bridge deck by an expansion bolt pair; B. Select high-sensitivity and high-precision pressure sensors, accelerometers and displacement sensors, and arrange pressure sensors on the outer wall of the water bag 4 and the joints of two adjacent box beams according to the predetermined grid or key points to fully capture the pressure distribution of the water bag 4 during the shaking process; at the same time, arrange accelerometers and displacement sensors at key locations such as nodes and supports of the bridge to monitor the dynamic response of the bridge; Before the experiment, all pressure sensors, accelerometers and displacement sensors are calibrated and debugged to ensure the accuracy and reliability of the measurement results of all pressure sensors, accelerometers and displacement sensors; calibration can be completed by comparison with known standard values ​​or by using special calibration equipment; C. Start the simulator 1 gradually through the controller, so that the hydraulic cylinder 2 extends until the push plate 3 abuts against the water bag 4, until the push plates 3 on all simulators 1 abut against the water bag 4. While completing the preparation work, observe whether each simulator 1 can work normally. If a fault occurs, it should be repaired quickly to avoid affecting the test progress; wherein, the middle part of the push plate 3 is a plane, and the left and right sides are arc-shaped surfaces. The middle plane and part of the arc-shaped surface of the push plate 3 are in contact with the water bag 4, so that the water bag 4 can be pushed and the water bag 4 can be avoided from being punctured; D. Use the controller to push out all the hydraulic cylinders 2 on the simulator 1 at the same speed, and then quickly retract them. When the water bag 4 deviates toward the simulator 1 and contacts the push plate 3, start the controller to push out the hydraulic cylinder 2. The pushing frequency is based on the actual wind conditions and the natural frequency of the bridge model, and the shaking frequency range is preliminarily set. Generally, the frequency should cover the possible resonance frequencies of the bridge model to comprehensively evaluate the wind resistance of the bridge. In addition, since the magnitude of the pushing amplitude directly affects the magnitude of the dynamic pressure of the simulated wind load, it is necessary to set a reasonable amplitude range based on the test requirements and the size of the bridge. Excessive amplitude may cause the water bag 4 to rupture or the supporting structure to be damaged, so it needs to be selected with caution. The shaking force of the hydraulic cylinder 2 determines the intensity and direction of the simulated wind load. The wind loads at different wind speeds and wind directions can be simulated by adjusting the output force of the hydraulic cylinder 2. The magnitude of the force should be determined based on the test requirements and the bearing capacity of the bridge. E. When the water bag 4 swings at the set frequency, start measuring the dynamic load. After the measurement is completed, start the hydraulic cylinder 2 to make the push plate 3 contact the water bag 4 and move together. Reduce the extension and retraction speed of the hydraulic cylinder 2 so that the water bag 4 stops swinging completely. After the dynamic load is completed, remove the expansion bolt pair that fixes the simulator 1 on the bridge deck, and restore the bridge deck to a flat surface by pouring concrete into the holes. F. After the experiment, conduct a preliminary analysis of the collected data, clean the original data, and remove interference factors such as outliers and noise; ensure the accuracy and reliability of the data to provide a good basis for subsequent analysis; according to the measurement data of the pressure sensor, interpolate or fit the pressure values ​​of each pressure sensor to calculate the pressure distribution on the wall of the water bag 4 and the end face of the bridge; draw the time domain response curve of the bridge according to the measurement data of the accelerometer and displacement sensor; by observing the parameters of the vibration frequency, amplitude and displacement of the time domain response curve, the dynamic performance of the bridge can be evaluated; use fast Fourier transform to perform frequency domain conversion on the time domain response curve to obtain a spectrum diagram; through the spectrum diagram, the parameters such as the resonance frequency and damping ratio of the bridge can be analyzed to further evaluate the wind resistance of the bridge; G. Compare the experimental results with the theoretical expected values ​​to verify whether the dynamic pressure effect of the simulated wind load and the wind resistance performance of the bridge model meet expectations; the theoretical expected values ​​adopt the numerical water pool method, which uses computer simulation technology to construct a numerical water pool, solves the fluid mechanics equations through numerical methods, and simulates the movement and force of the bridge model under complex wind environments to obtain the theoretical expected values; H. Finally, the relationship between the dynamic load of the water bag 4 and the wind force level and the bearing time is obtained, and the relationship is used to determine what level of wind force the bridge can withstand and how long the load lasts.

[0015] In addition, during the experiment, attention should always be paid to the safety status of the experimental equipment, especially the integrity of the water bag 4 and the stability of the supporting structure; once an abnormal situation is found, the experiment should be stopped immediately and measures should be taken to deal with it; and a detailed emergency plan should be formulated, including possible emergencies such as rupture of the water bag 4, damage to the supporting structure, and failure of the pressure sensor, accelerometer and displacement sensor, to ensure that various emergencies can be responded to quickly and effectively during the experiment.

[0016] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A test method for the deformation law of ballastless track of a long-span bridge using load replacement simulation, characterized in that: The following steps are involved: A. Pour water into the water bag. After using the water bag to complete the static load on the bridge, install a simulator with a hydraulic cylinder and a push plate on one side of the water bag. The hydraulic cylinder is connected to an external controller. B. Arrange pressure sensors on the outer wall of the water bag and at the joints of two adjacent box girders according to the predetermined grids or key points to fully capture the pressure distribution during the shaking of the water bag; at the same time, arrange accelerometers and displacement sensors at key locations such as nodes and supports of the bridge to monitor the dynamic response of the bridge; C. Start the simulator gradually through the controller, so that the hydraulic cylinder extends until the push plate abuts against the water bag, until the push plates on all simulators abut against the water bag; D. Use the controller to control all the hydraulic cylinders on the simulator to push out at the same speed, and then quickly retract. When the water bag deviates toward the simulator and contacts the push plate, start the controller to push out the hydraulic cylinders. E. When the water bag swings at the set frequency, start measuring the dynamic load. After the measurement is completed, start the hydraulic cylinder to make the push plate contact the water bag and move together, and reduce the extension and retraction speed of the hydraulic cylinder so that the water bag stops swinging completely; F. After the experiment, the collected data is preliminarily analyzed. According to the measurement data of the pressure sensor, the pressure distribution of the water bag wall and the end face of the bridge is calculated by interpolating or fitting the pressure values ​​of each pressure sensor; the time domain response curve of the bridge is drawn according to the measurement data of the accelerometer and displacement sensor; the dynamic performance of the bridge can be evaluated by observing the parameters of the vibration frequency, amplitude and displacement of the time domain response curve; the time domain response curve is converted into the frequency domain using fast Fourier transform to obtain a spectrum diagram; the resonance frequency and damping ratio of the bridge can be analyzed through the spectrum diagram to further evaluate the wind resistance of the bridge; G. Compare the experimental results with the theoretical expected values ​​to verify whether the dynamic pressure effect of the simulated wind load and the wind resistance performance of the bridge model meet expectations; the theoretical expected values ​​adopt the numerical water pool method, which uses computer simulation technology to construct a numerical water pool, solves the fluid mechanics equations through numerical methods, and simulates the movement and force of the bridge model under complex wind environments to obtain the theoretical expected values; H. Finally, the relationship between the dynamic load of the water bag, the wind force level, and the bearing time is obtained. Through this relationship, it can be determined what level of wind force the bridge can withstand and how long the load can last.

2. The test method for deformation law of ballastless track of long-span bridges using load replacement simulation according to claim 1 is characterized in that: The specifications of the water bag are 1.8m×1.3m×11.5m, and no less than 10 sets of simulators are arranged along the length of the water bag.

3. The test method for deformation law of ballastless track of long-span bridge using load replacement simulation according to claim 1 is characterized by: The water bag is filled with 27t of water to achieve a ballast load of 42kN / m.

4. The test method for deformation law of ballastless track of long-span bridge using load replacement simulation according to claim 1 is characterized by: After the dynamic load is completed, the expansion bolt pair that fixes the simulator to the bridge deck is removed, and the bridge deck is restored to a flat surface by pouring concrete into the holes.

5. The test method for deformation law of ballastless track of long-span bridge using load replacement simulation according to claim 1 is characterized by: The middle part of the push plate is a plane, and the left and right sides are arc-shaped surfaces. The middle plane and part of the arc-shaped surface of the push plate are in contact with the water bag.

6. The test method for deformation law of ballastless track of long-span bridges using load replacement simulation according to claim 1 is characterized by: Two groups of hydraulic cylinders are placed in the simulator, and a protective telescopic rod is arranged between the two groups of hydraulic cylinders. The protective telescopic rod is connected to the controller, and the protective telescopic rod and the hydraulic cylinders do not belong to the same hydraulic system.

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