Experimental device and method for simulating real form of high-speed rail simply-supported box girder crack

Abstract

The invention discloses an experimental device and method for simulating the real form of a crack of a high-speed rail simply-supported box girder, and the device comprises a high-speed rail simply-supported box girder structure model, one side of the high-speed rail simply-supported box girder structure model is provided with an initial prefabricated crack region, and the initial prefabricated crack region is provided with a crack monitoring system; the crack monitoring system comprises an acoustic emission sensor and a crack acquisition instrument, and the acoustic emission sensor and the crack acquisition instrument are respectively connected with the data acquisition instrument; and a crack secondary expansion excitation device is arranged on the outer side of the high-speed rail simply-supported box girder structure model. According to the device, a bridge structure model provided with an initial prefabricated crack and a secondary expansion excitation device are used for inducing secondary expansion of the crack until a crack tip is formed, so that crack evolution in an actual bridge structure is restored; and the crack monitoring system monitors the expansion condition of the crack in real time and accurately transmits data to the data acquisition equipment. The device can capture key data in crack development and ensure the accuracy and reliability of experimental results.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering technology, and in particular to an experimental device and method for simulating the true morphology of cracks in simply supported box girders of high-speed railways. Background Technology

[0002] During high-speed train operation, bridge structures are typically subjected to vibrations from passing trains. While these vibrations usually do not cause significant damage to the bridge in the short term, in the long run, the continuous and repeated application of dynamic loads can lead to fatigue accumulation in the bridge structure. This fatigue effect gradually evolves into cracks in critical parts of the bridge structure, such as the joints of simply supported beam bridges or areas of stress concentration. These cracks may further expand with the continued application of dynamic loads and ultimately pose a serious threat to the overall structural safety of the bridge.

[0003] To conduct in-depth research and simulation of crack propagation behavior in bridges under long-term high-speed train operation conditions, an experimental device capable of simulating the crack morphology of real bridges has been developed. This device applies vibration loads similar to those generated when a high-speed train passes, and, in conjunction with a precise crack monitoring system, can reproduce the formation and propagation process of cracks in bridge structures. Using this experimental device, the development of cracks in simply supported beam bridges on high-speed railways under prolonged dynamic loads can be simulated, thus providing crucial experimental data support for bridge safety assessment and maintenance strategy development.

[0004] However, existing experimental devices for simulating the true morphology of cracks in simply supported box girders of high-speed railways do not consider the secondary propagation of cracks, thus failing to accurately reproduce the crack evolution in actual bridge structures, resulting in low accuracy and reliability of experimental results. Summary of the Invention

[0005] The main objective of this invention is to provide an experimental device and method for simulating the true morphology of cracks in simply supported box girders of high-speed railways, in order to solve the technical problem that the existing technology cannot accurately reproduce the crack evolution in actual bridge structures, resulting in low accuracy and reliability of experimental results.

[0006] To achieve the above objectives, the present invention provides an experimental device for simulating the actual morphology of cracks in a simply supported box girder of a high-speed railway, comprising: a structural model of a simply supported box girder of a high-speed railway, wherein an initial precast crack area is set on one side of the structural model of the simply supported box girder of the high-speed railway, and a crack monitoring system is arranged in the initial precast crack area; the crack monitoring system includes an acoustic emission sensor and a crack acquisition instrument, the acoustic emission sensor and the crack acquisition instrument being connected to a data acquisition instrument respectively; and a crack secondary propagation excitation device is provided on the outside of the structural model of the simply supported box girder of the high-speed railway.

[0007] Optionally, the crack secondary propagation excitation device includes a waveform generator, a power amplifier, and a vibrator. The waveform generator is connected to the power amplifier, the power amplifier is connected to the vibrator, and a dynamic pressure sensor is installed at the bottom of the vibrator.

[0008] Optionally, the initial precast crack area is further expanded to form a crack tip.

[0009] Optionally, the crack secondary propagation excitation device is a high-speed train load loading system.

[0010] This application also provides a method for simulating the true morphology of cracks in simply supported box girders of high-speed railways, based on any of the above-mentioned experimental devices for simulating the true morphology of cracks in simply supported box girders of high-speed railways, including the following steps: S10, a high-speed railway simply supported box girder structure model was made using a preset similarity ratio; S20, based on the high-speed railway simply supported box girder structure model, forms a crack combination device; S30. The crack assembly device is tightly wrapped with plastic wrap to ensure that the surface of the crack assembly device is completely covered and the edges are sealed. According to the preset crack location requirements, the wrapped device is placed in the bottom area of ​​the web of the mid-span section of the high-speed railway simply supported box girder structure model and fixed in place. The entire high-speed railway simply supported box girder structure model is then subjected to standard curing. S40, after the curing of the high-speed railway simply supported box girder structure model is completed, the initial precast cracks are obtained, and the initial precast cracks are preliminarily measured. S50, the crack secondary propagation induction device is arranged on the outside of the high-speed railway simply supported box girder structure model to cause the initial precast cracks to propagate secondary, and the secondary propagation status of the initial precast cracks is monitored at the same time. S60, when the crack monitoring system collects a crack secondary propagation signal, remove the crack secondary propagation excitation device; The S70 uses a crack acquisition instrument to measure the size and shape of the initial precast cracks and crack tips.

[0011] Optionally, step S20 includes: S201. Calculate the number of prefabricated crack units required based on the required size of the prefabricated cracks in the high-speed railway simply supported box girder structural model. S202, the crack prefabrication units are combined horizontally and vertically to form a crack assembly device, which includes vertically combined crack prefabrication units and horizontally combined crack prefabrication units.

[0012] Optionally, step S40 includes: S401, After the high-speed railway simply supported box girder structure model has been cured, the crack assembly device is removed to obtain the initial precast cracks; S402, a crack acquisition instrument is used to perform preliminary measurements on the initial precast cracks to ensure that the size of the initial precast cracks meets the requirements.

[0013] Optionally, the crack prefabrication unit is a polyimide sheet.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides an experimental device for simulating the real-world crack morphology of simply supported box girders in high-speed railways. By using a bridge structure model with pre-existing cracks and a secondary propagation induction device, the device can induce secondary crack propagation until a crack tip is formed, thus highly replicating the crack evolution in actual bridge structures. A crack monitoring system monitors crack propagation in real time and accurately transmits the data to a data acquisition device. This device can capture key data during crack development, ensuring the accuracy and reliability of experimental results. Furthermore, this device is suitable for simulating various dynamic load conditions, especially the dynamic loads of frequent high-speed train passage. With an adjustable load loading system, this invention can adapt to different experimental conditions and is widely applicable to the research and monitoring of cracks in bridge structures. Attached Figure Description

[0015] Figure 1 This is an overall structural diagram of an experimental device for simulating the true morphology of cracks in a simply supported box girder of a high-speed railway, according to the present invention. Figure 2 This is a flowchart of a method for simulating the true morphology of cracks in a simply supported box girder of a high-speed railway according to the present invention; Figure 3 A schematic diagram of the crack prefabrication unit and crack assembly device provided in an embodiment of the present invention; Figure 4 The vibration load curve of a high-speed train at a speed of 300 km / h is provided for an embodiment of the present invention.

[0016] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0017] The attached figures are labeled as follows: 1. Initial precast crack; 2. High-speed railway simply supported box girder structural model; 3. Crack monitoring system; 4. Acoustic emission sensor; 5. Crack acquisition instrument; 6. Data acquisition instrument; 7. Crack secondary propagation excitation device; 8. Crack tip; 9. Waveform generator; 10. Power amplifier; 11. Vibrator; 12. Dynamic pressure sensor; 13. Crack precast unit; 14. Vertically combined crack precast unit; 15. Horizontally combined crack precast unit. Detailed Implementation

[0018] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the scope of this application. Rather, these embodiments are provided to make this disclosure more thorough and complete, and to fully convey the scope of this disclosure to those skilled in the art.

[0019] This embodiment provides an experimental device for simulating the actual morphology of cracks in simply supported box girders of high-speed railways, such as... Figure 1 As shown, the experimental setup includes a high-speed railway simply supported box girder structure model 2. An initial precast crack area 1 is set on one side of the high-speed railway simply supported box girder structure model 2, and a crack monitoring system 3 is arranged in the initial precast crack area 1. The crack monitoring system 3 includes an acoustic emission sensor 4 and a crack acquisition instrument 5, which are respectively connected to a data acquisition instrument 6. A crack secondary propagation excitation device 7 is set on the outside of the high-speed railway simply supported box girder structure model 2.

[0020] Among them, the crack secondary propagation excitation device 7 is a high-speed train load loading system, and the crack secondary propagation excitation device 7 is used to guide the secondary propagation of the initial precast crack to form the crack tip 8.

[0021] In addition, the data acquisition unit 6 is connected to a computer for controlling and recording experimental data.

[0022] Furthermore, before establishing the experimental setup to simulate the true morphology of cracks in a simply supported box girder of a high-speed railway, it is necessary to obtain various similarity relationships required for the experiment. These similarity relationships can be obtained using dimensional analysis, as shown in Table 1. Table 1

[0023] Note: C l C v C t C a C ρ C f Both represent similarity constants.

[0024] Taking the actual concrete parameters of a simply supported beam bridge structure of the JS high-speed railway as an example, in this embodiment, the similar model is characterized by good fluidity and micro-expansion, which is very suitable for the casting of small-scale concrete structures. Grouting material is selected to make the model, and the test parameters of the model are shown in Table 2: Table 2

[0025] In an exemplary embodiment, the crack secondary propagation excitation device 7 includes a waveform generator 9, a power amplifier 10, and an exciter 11. The waveform generator 9 is connected to the power amplifier 10, the power amplifier 10 is connected to the exciter 11, and a dynamic pressure sensor 12 is provided at the bottom of the exciter 11.

[0026] In an exemplary embodiment, the initial precast crack region 1 is expanded a second time to form a crack tip 8.

[0027] Specifically, the vibrator 11 transmits the load to the high-speed railway simply supported box girder structure model 2 through the dynamic pressure sensor 12 set at the bottom, causing the crack to expand secondary and form the crack tip 8.

[0028] This invention provides an experimental device for simulating the actual morphology of cracks in simply supported box girders of high-speed railways. By using a bridge structure model with pre-existing cracks and a secondary propagation induction device, the device can induce secondary crack propagation until a crack tip is formed, thus highly replicating the crack evolution in actual bridge structures. A crack monitoring system monitors the crack propagation in real time and accurately transmits the data to a data acquisition device. This device can capture key data during crack development, ensuring the accuracy and reliability of experimental results. Furthermore, this device is suitable for simulating various dynamic load conditions, especially the dynamic loads of frequent high-speed train passage. With an adjustable load loading system, this invention can adapt to different experimental conditions and is widely applicable to the research and monitoring of cracks in bridge structures.

[0029] This invention also provides a method for simulating the true morphology of cracks in simply supported box girders of high-speed railways, based on the experimental apparatus described above for simulating the true morphology of cracks in simply supported box girders of high-speed railways, such as... Figure 2 The method includes the following steps: S10. A high-speed railway simply supported box girder structure model 2 was made using a preset similarity ratio (1:48). This model is similar to the actual high-speed railway simply supported beam bridge structure to ensure the effectiveness of the experimental conditions. S20, based on the high-speed railway simply supported box girder structural model 2, forms a crack combination device; S30, the crack assembly device is tightly wrapped with plastic wrap to ensure that the surface of the crack assembly device is completely covered and the edges are sealed to prevent the grout from seeping in during the concrete pouring process. According to the preset crack location requirements, the wrapped device is placed in the bottom area of ​​the web of the mid-span section of the high-speed railway simply supported box girder structure model 2 and fixed in place. The entire high-speed railway simply supported box girder structure model 2 is then subjected to standard curing. S40. After the high-speed railway simply supported box girder structure model 2 is cured, the initial precast crack 1 is obtained, and the initial precast crack 1 is initially measured to ensure that the size of the initial precast crack 1 meets the requirements, so as to realize the simulation of the macroscopic crack zone of the high-speed railway simply supported beam bridge. S50, the crack secondary propagation stimulating device 7 is arranged on the outside of the high-speed railway simply supported box girder structure model 2 to cause the initial precast crack 1 to propagate secondary, and at the same time monitor the secondary propagation status of the initial precast crack 1. S60, when the crack monitoring system 3 collects the crack secondary propagation signal, the crack secondary propagation excitation device 7 is removed. At this time, the initial precast crack 1 has completed secondary propagation and formed the crack tip 8, realizing the simulation of the crack micro-crack zone of the high-speed railway simply supported beam bridge. S70 uses a crack acquisition instrument 5 to measure the size and shape of the initial precast crack 1 and crack tip 8. At this point, the true form of cracks in high-speed railway simply supported beam bridges in actual engineering can be highly reproduced.

[0030] In an exemplary embodiment, step S20 includes: S201, Calculate the number of prefabricated crack units 13 required based on the required size of the prefabricated crack in the high-speed railway simply supported box girder structure model 2. S202, the two precast crack units 13 are combined horizontally and vertically to form a structure as shown in the figure. Figure 3 The crack assembly device shown includes vertically assembled crack prefabrication units 14 and horizontally assembled crack prefabrication units 15.

[0031] Among them, the crack prefabrication unit 13 is a polyimide sheet with a unit size of 0.5 mm. 2cm 2cm.

[0032] In an exemplary embodiment, step S40 includes: S401, After the high-speed railway simply supported box girder structure model 2 is cured, the crack assembly device is removed to obtain the initial precast crack 1. S402, the crack acquisition instrument 5 is used to perform preliminary measurement on the initial precast crack 1 to ensure that the size of the initial precast crack 1 meets the requirements.

[0033] In the above embodiments, the following formula is used to simulate the vibration load generated by the train during its movement:

[0034] Where: F(t) is the vibration load; k1 is the superposition coefficient between adjacent wheel and rail; k2 is the wheel-rail force dispersion coefficient; P0 is the static load of a single wheel; P i For a typical vibration load under non-stationary control conditions, i = 1, 2, 3; ω i ω is the angular frequency of vibration at the corresponding vehicle speed. i =2πv / Li, where v is the train speed and Li is the wavelength of the geometrically irregular curve.

[0035] Based on a certain type of electric multiple unit (EMU), the static wheel weight on one side of the train is determined to be P0 = 75kN. Referring to the UK's track irregularity management values, a higher high-speed railway operating standard is selected. The irregularity vibration wavelength Li and the corresponding sag values ​​ai are: L1 = 10m, a1 = 3.5mm; L2 = 2m, a2 = 0.4mm; L3 = 0.5m, a3 = 0.08mm; v = 300km / h is taken, k1 is taken as 1.5, and k2 as 0.7. At this time, the vibration load curve generated by the high-speed train at a speed of 300km / h is as follows: Figure 4 As shown.

[0036] In the description of this application, it should be noted that the terms "first", "second", and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0038] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the coupling or direct coupling or communication connection shown or discussed may be through some communication interface; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0039] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0040] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0041] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device, such as a personal computer, server, or network device, to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0042] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of protection of the claims.

[0043] Furthermore, although the operations of the method of this application are described in a specific order in the accompanying drawings, this does not require or imply that these operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

Claims

1. An experimental device for simulating the actual morphology of cracks in simply supported box girders of high-speed railways, characterized in that, include: A high-speed railway simply supported box girder structure model (2) is provided on one side of the high-speed railway simply supported box girder structure model (2), and a crack monitoring system (3) is arranged in the initial precast crack area (1); The crack monitoring system (3) includes an acoustic emission sensor (4) and a crack acquisition instrument (5), which are respectively connected to the data acquisition instrument (6); a crack secondary propagation excitation device (7) is provided on the outside of the high-speed railway simply supported box girder structure model (2).

2. The experimental device for simulating the true morphology of cracks in a simply supported box girder of a high-speed railway according to claim 1, characterized in that: The crack secondary propagation excitation device (7) includes a waveform generator (9), a power amplifier (10) and a vibrator (11). The waveform generator (9) is connected to the power amplifier (10), and the power amplifier (10) is connected to the vibrator (11). A dynamic pressure sensor (12) is provided at the bottom of the vibrator (11).

3. The experimental device for simulating the true morphology of cracks in a simply supported box girder of a high-speed railway according to claim 1, characterized in that: The initial precast crack area (1) is expanded a second time to form a crack tip (8).

4. The experimental device for simulating the true morphology of cracks in a simply supported box girder of a high-speed railway according to claim 3, characterized in that: The crack secondary propagation excitation device (7) is a high-speed train load loading system.

5. A method for simulating the true morphology of cracks in a simply supported beam bridge of a high-speed railway, characterized in that, It employs an experimental apparatus for simulating the true morphology of cracks in a simply supported beam bridge of a high-speed railway, as described in any one of claims 1-4, and includes the following steps: S10, a high-speed railway simply supported box girder structural model was made using a preset similarity ratio (2); S20, based on the high-speed rail simply supported box girder structure model (2), a crack combination device is formed; S30, use plastic wrap to tightly wrap the crack assembly device to ensure that the surface of the crack assembly device is completely covered and the edges are sealed. According to the preset crack position requirements, place the wrapped device in the bottom area of ​​the web of the mid-span section of the high-speed railway simply supported box girder structure model (2), fix it in place, and perform standard maintenance on the entire high-speed railway simply supported box girder structure model (2). S40, after the high-speed rail simply supported box girder structure model (2) has been cured, the initial precast crack (1) is obtained, and the initial precast crack (1) is initially measured; S50, the crack secondary propagation stimulating device (7) is arranged on the outside of the high-speed railway simply supported box girder structure model (2) to cause the initial precast crack (1) to propagate secondary, and the secondary propagation status of the initial precast crack (1) is monitored at the same time. S60, when the crack monitoring system (3) collects the crack secondary propagation signal, the crack secondary propagation excitation device (7) is removed; S70, a crack acquisition instrument (5) is used to measure the size and shape of the initial precast crack (1) and the crack tip (8).

6. The method for simulating the true morphology of cracks in a simply supported box girder of a high-speed railway according to claim 5, characterized in that, Step S20 includes: S201, Calculate the number of prefabricated crack units (13) required based on the size of the prefabricated cracks required in the high-speed rail simply supported box girder structure model (2); S202, the crack prefabrication unit (13) is combined in the horizontal and vertical directions to form a crack assembly device, which includes vertically combined crack prefabrication unit (14) and horizontally combined crack prefabrication unit (15).

7. The method for simulating the true morphology of cracks in a simply supported box girder of a high-speed railway according to claim 5, characterized in that, Step S40 includes: S401, After the high-speed rail simply supported box girder structure model (2) is cured, the crack assembly device is taken out to obtain the initial prefabricated crack (1); S402, a crack acquisition instrument (5) is used to perform preliminary measurement on the initial precast crack (1) to ensure that the size of the initial precast crack (1) meets the requirements.

8. The method for simulating the true morphology of cracks in a simply supported box girder of a high-speed railway according to claim 5, characterized in that: The crack prefabrication unit (13) is a polyimide sheet.

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