An experimental method for deformation law of long-span bridge ballastless track by load replacement simulation

Abstract

The present application relates to a kind of test method of deformation law of long-span bridge ballastless track using load replacement simulation, comprising the following steps: using water bag to complete static load, simulator with hydraulic cylinder and push plate is installed on the side of water bag;Simulator is gradually started by controller to make hydraulic cylinder extend until push plate and water bag abut, until the push plate on all simulators and water bag abut;Hydraulic cylinder on all simulators is made to push out at the same speed by controller control hydraulic pump, then quickly contract, water bag is offset to simulator and contacted with push plate, then start controller to make hydraulic cylinder push out;When water bag swings according to set frequency, start to measure dynamic load, after measurement is completed, start hydraulic cylinder to make push plate and water bag contact and move together, reduce the extension and contraction speed of hydraulic cylinder so that water bag completely stops swinging, the present application has the advantage that water bag can be used for static load test and dynamic load test.

Description

Technical Field

[0001] The present 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 cable-stayed bridges with steel-concrete composite beams utilize multi-directional supports throughout, creating a semi-floating system. Under the influence of temperature and wind loads, the bridges experience large and complex displacements and deformations. Studying the laws governing bridge deformation and displacement to ensure that linear control during ballastless track construction is responsive to bridge deformation is crucial for ensuring high smoothness, stability, and 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 like this:

[0006] A test method for the deformation law of ballastless track of a long-span bridge using load replacement simulation is characterized by comprising the following steps:

[0007] A. Fill the water bag with water. 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.

[0008] B. Pressure sensors are placed on the outer wall of the water bag and at the joints between two adjacent box girders according to a predetermined grid or key points to fully capture the pressure distribution during the shaking of the water bag. At the same time, accelerometers and displacement sensors are placed at key locations such as nodes and supports of the bridge to monitor the dynamic response of the bridge.

[0009] C. Start the simulators gradually through the controller, extending the hydraulic cylinder until the push plates abut against the water bags, and until the push plates on all the simulators abut against the water bags;

[0010] D. Use the controller to control all the hydraulic cylinders on the simulator to push out at the same speed, and then quickly retract. Wait until the water bag deviates toward the simulator and contacts the push plate, and then start the controller to push the hydraulic cylinder out.

[0011] E. Start measuring the dynamic load when the water bag swings at the set frequency. After the measurement is completed, start the hydraulic cylinder to make the push plate contact the water bag and move together. Reduce the extension and retraction speed of the hydraulic cylinder so that the water bag stops swinging completely.

[0012] F. After the experiment, conduct a preliminary analysis of the collected data. Based on the measurement data of the pressure sensors, interpolate or fit the pressure values ​​of each pressure sensor to calculate the pressure distribution on the water bag wall and the bridge end face. Based on the measurement data of the accelerometer and displacement sensor, draw the time domain response curve of the bridge. By observing the vibration frequency, amplitude, and displacement parameters of the time domain response curve, the dynamic performance of the bridge can be evaluated. Use fast Fourier transform to convert the time domain response curve into the frequency domain to obtain a spectrum diagram. The spectrum diagram can be used to analyze the resonance frequency and damping ratio of the bridge and further evaluate the wind resistance performance of the bridge.

[0013] 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 ​​are obtained using the numerical water pool method, which uses computer simulation technology to construct a numerical water pool and numerically solve fluid mechanics equations to simulate the movement and force of the bridge model in a complex wind environment.

[0014] H. Finally, the relationship between the dynamic load of the water bag, wind force level, and bearing time is obtained. This relationship is used to determine what level of wind force the bridge can withstand and how long the load lasts.

[0015] 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 of the water bag.

[0016] 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.

[0017] As a further illustration of the present invention, preferably, after the dynamic load is completed, the expansion bolts fixing the simulator to the bridge deck are removed, and the bridge deck is restored to a smooth surface by pouring concrete into the holes.

[0018] 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 surfaces of the push plate are in contact with the water bag.

[0019] 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.

[0020] The above technical solution of the present invention has the following advantages:

[0021] 1. Through the design of the application, the water bag can be subjected to static load pressure, and can be subjected to lateral swing through the movement of the mechanical structure composed of the hydraulic cylinder and the push plate. With the same frequency swing of multiple water bags, 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 static load test and dynamic load test.

[0022] 2. The mechanical structure adopts assembly design, which is convenient for disassembly, transportation and multiple use.

[0023] 3. In the use process, the impact of the water bag on the hydraulic cylinder can be limited by the damping of the protective telescopic rod, and the service life of the simulator can be prolonged.

[0024] 4. The structure is simple and easy to use, which can greatly improve the work efficiency, save a lot of funds, and avoid the error that the data of the maximum wind load that can be borne obtained by simulation calculation is too different from the actual construction effect. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is the overall assembly effect diagram of the application;

[0026] Figure 2 is Figure 1 the enlarged view of A in

[0027] Figure 3 is the partial top view of the application;

[0028] In the drawing: 1, simulator; 2, hydraulic cylinder; 3, push plate; 4, water bag; 5, protective telescopic rod. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme in the embodiments of the application will be described clearly and completely below in combination with the drawings in the embodiments of the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the application.

[0030] A test method for the deformation law of long-span bridge ballastless track by load replacement simulation, combining Figure 1-Figure 3 , comprising the following steps:

[0031] A. Use a water bag 4 with specifications of 1.8m×1.3m×11.5m and fill it with 27t of water to achieve a 42kN / m ballast load. At this point, the water bag 4 is fully inflated and can perform a static load test on the bridge. After the water bag 4 completes 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. Place two sets of hydraulic cylinders 2 in the simulator 1, each connected to an external controller. A protective telescopic rod 5 is provided between the two sets of hydraulic cylinders 2. The protective telescopic rod 5 and the hydraulic cylinders 2 are not part of the same hydraulic system and can provide resistance when controlling the water bag 4 to stop, protecting the hydraulic cylinders 2 from contraction. Arrange no fewer than 10 sets of simulators 1 along the length of the water bag 4, each set of simulators 1 being fixed to the bridge deck with a pair of expansion bolts.

[0032] B. Select high-sensitivity, high-precision pressure sensors, accelerometers, and displacement sensors. Arrange pressure sensors on the outer wall of the water bag 4 and at the joints between two adjacent box girders according to a predetermined grid or key points to fully capture the pressure distribution during the shaking of the water bag 4. 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.

[0033] Before the experiment, all pressure sensors, accelerometers and displacement sensors should be 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 comparing with known standard values ​​or using special calibration equipment.

[0034] C. Start the simulator 1 gradually through the controller, extending the hydraulic cylinder 2 until the push plate 3 contacts the water bag 4. This process continues until the push plates 3 on all simulators 1 contact the water bag 4. While completing the preparatory work, observe whether each simulator 1 is functioning properly. If a malfunction occurs, repair it quickly to avoid affecting the test progress. The push plate 3 has a flat center and curved sides. The flat center and part of the curved sides of the push plate 3 contact the water bag 4, which can push the water bag 4 while avoiding puncturing it.

[0035] 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 preliminarily set according to the actual wind conditions and the natural frequency of the bridge model, and the shaking frequency range is 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 pushing amplitude directly affects the dynamic pressure of the simulated wind load, a reasonable amplitude range needs to be set according to the test requirements and the size of the bridge. Excessive amplitude may cause the water bag 4 to rupture or damage the supporting structure, 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 force should be determined according to the test requirements and the bearing capacity of the bridge.

[0036] E. Start measuring the dynamic load when the water bag 4 swings at the set frequency. 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 contraction speed of the hydraulic cylinder 2 so that the water bag 4 stops swinging completely. After the dynamic load is completed, remove the expansion bolts that fix the simulator 1 to the bridge deck, and restore the bridge deck to a flat surface by pouring concrete into the holes.

[0037] F. After the experiment, conduct a preliminary analysis of the collected data, clean the raw data, and remove interference factors such as outliers and noise to ensure the accuracy and reliability of the data, providing a good foundation for subsequent analysis. Based on 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. Based on the measurement data of the accelerometer and displacement sensor, draw the time domain response curve of the bridge. By observing the parameters such as 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 convert the time domain response curve into the frequency domain to obtain a spectrum diagram. The spectrum diagram can be used to analyze the parameters such as the resonance frequency and damping ratio of the bridge to further evaluate the wind resistance of the bridge.

[0038] 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 ​​are obtained using the numerical water pool method, which uses computer simulation technology to construct a numerical water pool and numerically solve fluid mechanics equations to simulate the movement and force of the bridge model in a complex wind environment.

[0039] H. Finally, the relationship between the dynamic load of the water bag 4, 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.

[0040] 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.

[0041] 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 various embodiments of the present invention.

Claims

1. A test method for the deformation law of ballastless track on long-span bridges using load replacement simulation, characterized by: The following steps are involved: A. Fill the water bag with water. 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. Pressure sensors are placed on the outer wall of the water bag and at the joints between two adjacent box girders according to a predetermined grid or key points to fully capture the pressure distribution during the shaking of the water bag. At the same time, accelerometers and displacement sensors are placed at key locations such as nodes and supports of the bridge to monitor the dynamic response of the bridge. C. Start the simulators gradually through the controller, extending the hydraulic cylinder until the push plates abut against the water bags, and until the push plates on all the simulators abut against the water bags; D. Use the controller to control all the hydraulic cylinders on the simulator to push out at the same speed, and then quickly retract. Wait until the water bag deviates toward the simulator and contacts the push plate, and then start the controller to push the hydraulic cylinder out. E. Start measuring the dynamic load when the water bag swings at the set frequency. After the measurement is completed, start the hydraulic cylinder to make the push plate contact the water bag and move together. Reduce the extension and retraction speed of the hydraulic cylinder so that the water bag stops swinging completely. F. After the experiment, conduct a preliminary analysis of the collected data. Based on the measurement data of the pressure sensors, interpolate or fit the pressure values ​​of each pressure sensor to calculate the pressure distribution on the water bag wall and the bridge end face. Based on the measurement data of the accelerometer and displacement sensor, draw the time domain response curve of the bridge. By observing the vibration frequency, amplitude, and displacement parameters of the time domain response curve, the dynamic performance of the bridge can be evaluated. Use fast Fourier transform to convert the time domain response curve into the frequency domain to obtain a spectrum diagram. The spectrum diagram can be used to analyze the resonance frequency and damping ratio of the bridge and further evaluate the wind resistance performance 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 ​​are obtained using the numerical water pool method, which uses computer simulation technology to construct a numerical water pool and numerically solve fluid mechanics equations to simulate the movement and force of the bridge model in a complex wind environment. H. Finally, the relationship between the dynamic load of the water bag, wind force level, and bearing time is obtained. This relationship is used to determine what level of wind force the bridge can withstand and how long the load lasts.

2. The test method for deformation law of ballastless track of long-span bridges using load replacement simulation according to claim 1 is characterized by: 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 bridges 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 method for testing deformation laws of ballastless track for long-span bridges 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 bridges 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 surfaces of the push plate are in contact with the water bag.

6. The method for testing deformation laws of ballastless track for 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 provided between the two groups of hydraulic cylinders. The protective telescopic rod is connected to the controller. The protective telescopic rod and the hydraulic cylinders do not belong to the same hydraulic system.

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