Method for verifying crack monitoring capability of turnout broken rail monitoring system

Abstract

The invention relates to a turnout broken rail monitoring system crack monitoring capability verification system and verification method. The system comprises a turnout broken rail monitoring system, a fatigue testing machine, a turnout full-scale assembly, a strain acquisition device, a video acquisition device and a flaw detection device. Fatigue crack monitoring based on a full-scale assembly is different from an existing artificial defect verification method using cutting and the like, and crack generation and expansion under the real working condition of a site can be restored to the greatest extent. Strain monitoring and video monitoring are applied at the same time, and a monitoring system is divided into four different performance judgment grades.

Description

Technical Field

[0001] The present invention relates to the field of track detection and monitoring, and in particular to a method for verifying the crack monitoring capability of a turnout broken rail monitoring system. Background Art

[0002] As the weakest link in the railway line, the turnout is subject to large longitudinal cyclic forces on movable components such as the point rail and the heart rail during its back-and-forth movement. Combined with thermal forces and cyclic loads from the train, this poses a high risk of cracking. Limited by the detection principles and methods of existing flaw detection equipment, it is impossible to detect cracks at the bottom of the rail. When small cracks continue to grow and develop under stress to the fracture threshold, the rail will undergo brittle fracture, posing a major safety hazard. In recent years, with the increasingly urgent need to monitor the structural safety of rail components in the turnout area, the ability to identify and monitor cracks and their expansion process has become the main performance requirement of the turnout broken rail monitoring system. China has also invested a lot of scientific research resources to tackle technical problems. Turnout broken rail monitoring systems based on carrier communication, surface acoustic wave, electrical measurement, ultrasonic guided wave and other principles have emerged one after another, and each system can identify damage to rail components.

[0003] During actual testing and application, the broken rail monitoring system typically verifies its performance on a single short rail piece using damage simulation methods such as a cutting machine before its official launch. The resulting simulated damage differs significantly from the fatigue damage experienced under actual operating conditions. Due to the sporadic and random nature of fatigue cracks, verifying the fatigue crack detection capabilities of the turnout broken rail monitoring system has been a pressing technical challenge.

[0004] Prior Art 1: Section 5.3.2, Short Rail Crack Detection Test Verification, in Dr. Xing Bo's dissertation "Research on Rail Crack Detection Methods Based on Ultrasonic Guided Waves," of Beijing Jiaotong University; Appendix A, "Functional Test Method for High-Speed Railway Turnout Monitoring System (JDS-300A)" of the "Provisional Technical Requirements for High-Speed Railway Turnout Monitoring System (JDS-300A)": When verifying the effectiveness of the rail crack detection method and testing the functionality of the monitoring system, an artificial cracking method is used to create long cracks or circular cracks in the rail head, rail waist, and rail foot regions of the short rail.

[0005] The artificial cracks produced by this method have formed notches at the corresponding positions and cannot be considered as cracks in the strict sense. Their morphology is quite different from that of fatigue cracks produced under rail working conditions, and cannot illustrate the detection ability of the detection method for fatigue cracks.

[0006] Prior art 2: Section 5.3.5, "Experimental Verification of Long Rail Crack Detection," of Dr. Xing Bo's dissertation, "Research on Rail Crack Detection Methods Based on Ultrasonic Guided Waves," from Beijing Jiaotong University; and Section 5.2.1, "The Impact of Rail Bottom Damage on Ultrasonic Guided Waves," of Wang Jialei's master's dissertation, "Research on Turnout Point Damage Detection Technology Based on Ultrasonic Guided Waves," from Shijiazhuang Tiedao University. Based on the fundamental principle of crack echo generation, where a sudden impedance change at the crack location triggers reflection of the guided wave signal, this method uses a coupled mass to create an impedance change, triggering signal reflection, thereby simulating a crack echo and verifying the detection method.

[0007] The main disadvantages of this method are: first, it can only be used to verify the performance of monitoring systems based on the principle of ultrasonic guided waves; second, it is impossible to verify the relationship between the simulated reflection echo of the mass block and the damage reflection echo of the fatigue crack, and thus it is impossible to explain the detection ability of the monitoring system's detection method for fatigue cracks. Summary of the Invention

[0008] In the existing methods for verifying the ability to detect rail cracks, the damage used is artificially simulated damage, which can only illustrate the system's detection and monitoring capabilities for simulated damage, but cannot verify its detection and monitoring performance for real fatigue cracks. In addition, some test methods have limitations and can only detect detection and monitoring methods and systems developed based on specific principles. The purpose of the present invention is to provide a method for verifying the crack monitoring capability of a switch rail breakage monitoring system, to create fatigue cracks close to on-site working conditions, to monitor the expansion process of fatigue cracks, to verify the detection and monitoring performance of the switch rail breakage monitoring system for fatigue cracks, and to make the performance verification test method have a wider applicability.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] A fatigue crack monitoring performance verification system for a turnout broken rail monitoring system, comprising: a turnout broken rail monitoring system, a fatigue testing machine, a turnout full-scale component, a strain acquisition device, a video acquisition device, and a flaw detection device;

[0011] The switch broken rail monitoring system is a monitoring system whose performance is to be verified, comprising a sensor, which is installed on a test rail and is used to collect rail monitoring signals;

[0012] The fatigue testing machine is the load source for crack propagation. The loading force, load ratio and loading frequency of the fatigue test can be set. At the same time, the load can be automatically unloaded after the loading cycle is completed.

[0013] The full-scale turnout assembly is laid on the test platform. The full-scale turnout assembly includes a test rail, a switch tie and a rail pad. The switch tie and rail pad both contain fastening components consistent with the on-site working conditions. The number of fasteners used can be flexibly adjusted according to the performance verification requirements.

[0014] An artificial defect is made on the test rail as a stress concentration point during the loading process. The rail section where the stress concentration point is located is the stress concentration section. A fatigue testing machine is set at the stress concentration section to perform cyclic loading on the test rail on the fatigue component. As the number of fatigue recording loading increases, the fatigue crack rail will extend upward from the stress concentration point along the stress concentration section;

[0015] The strain acquisition device monitors the rail strain of the test rail, wherein the stress monitoring value can be used as a redundant judgment indicator of the crack extension state. The video acquisition device is used to monitor the fracture state of the test rail to assist in verifying the ability to judge the fracture state.

[0016] Rail fatigue crack detection uses flaw detection equipment to measure the crack extension length during the crack propagation process.

[0017] Furthermore, the test platform after the full-scale components of the turnout are assembled can be used for testing rail components such as base rails, point rails, and wing rails. When the test rails are movable rails such as point rails and heart rails, they should be assembled according to the use conditions of their components. In addition to the test rails, base rails are also installed to assist in fixing the test rails.

[0018] Furthermore, the artificial defect position is set at the rail bottom by default, and can be set at the rail head, rail waist or rail bottom according to performance verification requirements, and the corresponding setting positions of the first strain gauge and the second strain gauge of the strain acquisition equipment are also adjusted accordingly.

[0019] Furthermore, the artificial defect is set at the bottom of the rail; the strain acquisition equipment includes a first strain gauge and a second strain gauge, the first strain gauge is set directly below the artificial defect damage at the bottom of the rail, and the second strain gauge is set at a position close to the artificial defect below the bottom of the rail.

[0020] Furthermore, the strain acquisition device also includes a third strain gauge and a fourth strain gauge, the third strain gauge is arranged at the projection position of the rail head centerline below the rail bottom, and the fourth strain gauge is arranged on the side of the rail bottom without artificial defects.

[0021] A method for verifying the fatigue crack monitoring performance of a switch rail breakage monitoring system is provided, using the aforementioned switch rail breakage monitoring system fatigue crack monitoring performance verification system, and the main steps are:

[0022] S0, test rail assembly, laying full-scale fatigue components of the turnout on the fatigue test platform, and installing the turnout broken rail monitoring system to be verified on the test rail;

[0023] S1, cyclic loading of the rail: artificial defects are made on the test rail as stress concentration points during the loading process. The rail section where the stress concentration point is located is the stress concentration section. The fatigue testing machine is set with specific loading parameters to perform cyclic loading on the test rail on the fatigue component at the stress concentration section;

[0024] S2, rail strain monitoring, uses strain acquisition equipment to monitor the state of the test rail. The stress monitoring value obtained is used as an indicator to judge the crack growth state and to select the appropriate time for flaw detection;

[0025] S3, video monitoring, during the cyclic loading process, use video acquisition equipment to record the cyclic loading process of the test rail. The video acquisition equipment has a storage function and can determine the specific time when a specific rail state occurs, thereby realizing the monitoring of the cyclic loading state of the test rail and obtaining the specific time of rail fracture.

[0026] S4, rail fatigue crack detection, using flaw detection equipment to measure the crack extension length during the crack propagation process;

[0027] S5, performance verification analysis, compares the crack extension length obtained by flaw detection measurement with the alarm status of the monitoring system at the corresponding length to verify the monitoring performance of the monitoring system for fatigue cracks and broken rail conditions.

[0028] Furthermore, the switch broken rail monitoring system remains in working condition throughout the entire performance verification process until the test rail fatigue breaks.

[0029] Furthermore, the full-size turnout assembly can be a single stock rail assembly, a base and point rail combination assembly, or a complete set of switches or frog assemblies; when the assembly is laid, the sleeper spacing and the sub-rail foundation are set according to the on-site laying conditions, and the sub-rail foundation can be a ballasted track bed or a ballastless track bed.

[0030] Furthermore, in step S3, when collecting strain, at least the strain values of the rail on and near the damage are collected. As the rail crack expands, the strain value will gradually increase. When the strain gauge on the damage exceeds the limit and fails, the crack generally enters the expansion stage. At this time, closer attention should be paid to the alarm status of the monitoring system, and the rail should be inspected in a timely manner to determine the crack expansion status.

[0031] Furthermore, in step S4, after the cyclic loading begins, the first detection cycle begins. If the monitoring system issues an alarm, loading should be immediately suspended and fatigue damage detection should be performed on the test rail. The detection position should be near the prefabricated damage. If fatigue crack growth occurs, the detected crack length L and the monitoring system alarm status are recorded. If the system does not issue an alarm, but the first strain gauge fails, the test loading is suspended and fatigue damage detection is performed on the test rail. If crack growth occurs, the crack length L is recorded. If no crack growth occurs, cyclic loading is continued for 50,000 times. After pausing loading, fatigue crack detection is performed and the crack length L is recorded until L ≥ 10 mm, at which point loading is suspended. The first detection cycle ends.

[0032] After the first detection cycle ends, the second detection cycle begins. Figure 5 As shown. Loading continues, cyclically loading for 30,000 cycles, then suspending loading and conducting fatigue crack detection. The crack length, L, and the monitoring system alarm status are recorded. If L ≥ 15 mm, loading continues until the test rail breaks. If L < 15 mm, fatigue testing continues for 30,000 cycles, then suspending loading and conducting fatigue crack detection. Loading continues until L ≥ 15 mm, and the rail breaks, at which point loading ends.

[0033] Furthermore, in step S5, when the monitoring system issues an initial alarm, the crack detection record at the time of the alarm is reviewed. If the crack grows and the monitoring system continues to alarm, the crack detection sensitivity of the monitoring system is the crack length L0 at the time of the initial alarm. If the crack grows and the monitoring system does not continue to alarm, the monitoring system is determined to have missed a warning. If the crack does not grow when the monitoring system initially alarms, the monitoring system is determined to have received a false alarm.

[0034] After a false alarm occurs, the monitoring system determines its false alarm status. If the false alarm does not occur continuously and a continuous alarm begins to sound during the crack growth process, the crack detection sensitivity of the monitoring system is the crack length L1 at which the continuous alarm is sounded. If the false alarm status persists, the monitoring system does not have crack detection capability. Similarly, if the monitoring system does not sound a continuous alarm during the crack growth process, the monitoring system does not have crack detection capability.

[0035] Furthermore, the monitoring system's ability to monitor rail breakage is judged. At this time, the specific moment of rail breakage should be confirmed through the stress monitoring unit and the video monitoring unit. When the monitoring system has the ability to monitor cracks, if the monitoring system can issue a higher level alarm when the rail breaks, the monitoring system can distinguish rail breakage events separately; if it cannot issue a higher level alarm when the rail breaks, the monitoring system cannot distinguish rail breakage events separately. In particular, the higher level alarm determination can be based on the alarm logic of the monitoring system to be verified. If the alarm logic does not distinguish between alarm levels, but has a separate rail break alarm mark, and is triggered when the rail breaks, the alarm state at this time should be equivalently determined to be a higher level alarm. When the monitoring system does not have the ability to monitor cracks, if the monitoring system can issue a higher level alarm or a separate rail break alarm mark when the rail breaks, the monitoring system has the ability to monitor rail breakage.

[0036] The present invention has the following advantages due to the adoption of the above technical solution:

[0037] This invention is primarily used for fatigue crack monitoring performance verification in turnout rail breakage monitoring systems. It is universally applicable to most monitoring systems developed based on these principles. This verification method, pioneered by using full-scale components for fatigue crack monitoring, distinguishes itself from existing verification methods that rely on artificial defects such as cutting. It can closely replicate the initiation and propagation of cracks under real-world operating conditions. It utilizes both strain monitoring and video monitoring, and categorizes the monitoring system into four different performance levels. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a flow chart of the fatigue crack monitoring performance verification method of the turnout broken rail monitoring system of the present invention;

[0039] Figure 2 This is a diagram showing the components of the fatigue crack monitoring performance verification system of the turnout broken rail monitoring system of the present invention;

[0040] Figure 3 This is a schematic diagram of the arrangement of the rail bottom strain gauge on the loading section of the present invention;

[0041] Figure 4 This is a schematic diagram of the first detection cycle of the present invention;

[0042] Figure 5 is a schematic diagram of the second detection cycle of the present invention;

[0043] Figure 6 It is a performance verification analysis diagram of the present invention;

[0044] In the accompanying drawings, 1 is a switch rail breakage monitoring system, 11 is a sensor; 2 is a fatigue testing machine; 3 is a full-scale fatigue component of a switch, 31 is a test rail, 311 is an artificial defect damage, 312 is a fatigue loading plane, and the rail foundation includes 32 switch sleepers and 33 rail pads; 4 is a strain acquisition device, 41 is a first strain gauge, 42 is a second strain gauge, 43 is a third strain gauge, and 44 is a fourth strain gauge; 5 is a video acquisition device, and 6 is a flaw detection device. DETAILED DESCRIPTION

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0046] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0047] The present invention provides a method for verifying the fatigue crack monitoring performance of a turnout broken rail monitoring system. The main steps are:

[0048] S0, test rail assembly, laying the full-scale turnout assembly 3 on the fatigue test platform, and installing the turnout broken rail monitoring system 2 to be verified on the test rail 31;

[0049] In particular, the turnout broken rail monitoring system should remain in working condition throughout the performance verification process until the test rail fatigue breaks.

[0050] Furthermore, the turnout full-scale fatigue assembly can be a single stock rail assembly, a base and point rail assembly, or a complete switch or frog assembly. During assembly installation, the sleeper spacing and sub-rail foundation are set according to on-site laying conditions. The sub-rail foundation can be either a ballasted or ballastless trackbed.

[0051] S1, cyclic loading of the rail. An artificial defect 311 is made on the test rail as a stress concentration point during loading. The rail section where the stress concentration point is located is the stress concentration section 312. The fatigue testing machine 2 is used to set specific loading parameters and cyclically load the test rail 31 on the fatigue component 3 at the stress concentration section 312.

[0052] Specifically, the width of the artificial defect is controlled within 0.5mm, the direction of the notch is along the vertical cross-section of the rail, and the length should not be too large. This creates a defective loading section at the defect location to facilitate stress concentration during cyclic loading. During cyclic loading, the center of the loading head is placed on the loading section.

[0053] S2, rail strain monitoring, using the strain acquisition device 4 to monitor the state of the test rail 31, wherein the stress monitoring value can be used as a redundant judgment indicator of the crack growth state;

[0054] S3, video monitoring, during the cyclic loading process, the video acquisition device 5 is used to record the cyclic loading process of the test rail. The video acquisition device has a storage function and can also determine the specific time when a specific rail state occurs, thereby realizing the monitoring of the cyclic loading state of the test rail and obtaining the specific time when the rail breaks.

[0055] In particular, when collecting strain, at least the strain values of the rails on and next to the damage should be collected. As the rail crack expands, the strain value will gradually increase. When the strain gauge on the damage exceeds the limit and fails, the crack generally enters the expansion stage. At this time, closer attention should be paid to the alarm status of the monitoring system, and the rails should be inspected in a timely manner to determine the crack expansion status.

[0056] S4, rail fatigue crack detection, using flaw detection equipment 6, to measure the crack extension length during the crack propagation process;

[0057] Specifically, flaw detection equipment, including but not limited to ultrasonic and X-ray testing, must meet online testing requirements. Specifically, the test rail's installation and relative position must not be altered before complete fracture, and the rail's position and component installation state must remain unchanged throughout the testing process. The first and second detection cycles are distinguished based on the system's alarm status, total load count, and crack growth progress. The timing of flaw detection varies within each detection cycle.

[0058] S5, performance verification analysis, compares the crack extension length obtained by flaw detection measurement with the alarm status of the monitoring system at the corresponding length to verify the monitoring performance of the monitoring system for fatigue cracks and broken rail conditions.

[0059] According to a method for verifying the fatigue crack monitoring performance of a turnout broken rail monitoring system provided by the present invention, the verification system is as follows: Figure 2 As shown, the turnout broken rail monitoring system 1 (hereinafter referred to as the monitoring system) is a monitoring system whose performance is to be verified. The sensor 11 is installed on the test rail and is used to collect rail monitoring signals.

[0060] The fatigue testing machine 2 is the load source for crack propagation. It is characterized in that the loading force, load ratio and loading frequency of the fatigue test can be set, and the load can be automatically unloaded after the loading cycle is completed.

[0061] The full-scale turnout assembly 3 is laid on the test platform, and includes at least a test rail 31, a switch sleeper 32 and a rail pad 33. The switch sleeper 32 and the rail pad 33 both include fastening components consistent with the on-site working conditions, and their usage quantity can be flexibly adjusted according to the performance verification requirements. The test platform after the full-scale assembly 3 is assembled can be used for testing of basic rails, point rails, wing rails and other rail components. It is worth noting that when the test rail is a movable rail component such as a point rail and a heart rail, it should be assembled according to the use conditions of its components. In addition to the test rail 31, a basic rail should also be installed to assist in fixing the test rail.

[0062] An artificial defect 311 is made on the test rail 31. The defect position can be set at the rail head, rail waist or rail bottom according to the performance verification requirements. Taking the rail bottom as an example, Figure 2 As shown, the first strain gauge 41 is arranged directly below the artificial defect 311 on the rail bottom, the second strain gauge 42 is arranged below the rail bottom close to the artificial defect, the optional third strain gauge 43 is arranged below the rail bottom at the projection position of the centerline of the rail head, and the optional fourth strain gauge 44 is arranged on the side of the rail bottom without the artificial defect.

[0063] The fatigue testing machine 2 is used to set specific loading parameters to perform cyclic loading on the test rail 31 on the fatigue component 3 at the stress concentration section 312. As the number of fatigue recording loading times increases, the fatigue cracked rail will extend upward from the stress concentration point along the stress concentration section.

[0064] After the cyclic loading starts, the first detection cycle begins. Figure 4 As shown. When the monitoring system issues an alarm, loading should be immediately suspended and fatigue damage detection should be performed on the test rail near the prefabricated damage. If fatigue crack growth occurs, the detected crack length L and the monitoring system alarm status should be recorded. If the system does not alarm, but the first strain gauge fails, test loading should be suspended and fatigue damage detection should be performed on the test rail. If crack growth occurs, the crack length L should be recorded. If no crack growth occurs, the loading cycle should continue for 50,000 cycles. After pausing loading, fatigue crack detection should be performed and the crack length L should be recorded until L ≥ 10 mm, at which point loading should be suspended. The first detection cycle ends.

[0065] After the first detection cycle ends, the second detection cycle begins. Figure 5As shown. Loading continues, cyclically loading for 30,000 cycles, then suspending loading and conducting fatigue crack detection. The crack length, L, and the monitoring system alarm status are recorded. If L ≥ 15 mm, loading continues until the test rail breaks. If L < 15 mm, fatigue testing continues for 30,000 cycles, then suspending loading and conducting fatigue crack detection. Loading continues until L ≥ 15 mm, and the rail breaks, at which point loading ends.

[0066] Perform performance verification analysis on the monitoring system, such as Figure 6 shown.

[0067] When the monitoring system issues its initial alarm, check the crack detection record at the time of the alarm. If the crack grows and the monitoring system continues to alarm, the crack detection sensitivity of the monitoring system is the crack length L0 at the time of the initial alarm. If the crack grows and the monitoring system does not continue to alarm, it is determined that the monitoring system has issued a false alarm. If the crack does not grow when the monitoring system issues its initial alarm, it is determined that the monitoring system has issued a false alarm.

[0068] After a false alarm occurs, the monitoring system determines its false alarm status. If the false alarm does not occur continuously and a continuous alarm begins to sound during the crack growth process, the crack detection sensitivity of the monitoring system is the crack length L1 at which the continuous alarm is sounded. If the false alarm status persists, the monitoring system does not have crack detection capability. Similarly, if the monitoring system does not sound a continuous alarm during the crack growth process, the monitoring system does not have crack detection capability.

[0069] Furthermore, the monitoring system's ability to monitor rail breakage is judged. At this time, the specific moment of rail breakage should be confirmed through the stress monitoring unit and the video monitoring unit. When the monitoring system has the ability to monitor cracks, if the monitoring system can issue a higher level alarm when the rail breaks, the monitoring system can distinguish rail breakage events separately; if it cannot issue a higher level alarm when the rail breaks, the monitoring system cannot distinguish rail breakage events separately. In particular, the higher level alarm determination can be based on the alarm logic of the monitoring system to be verified. If the alarm logic does not distinguish between alarm levels, but has a separate rail break alarm mark, and is triggered when the rail breaks, the alarm state at this time should be equivalently determined to be a higher level alarm. When the monitoring system does not have the ability to monitor cracks, if the monitoring system can issue a higher level alarm or a separate rail break alarm mark when the rail breaks, the monitoring system has the ability to monitor rail breakage.

[0070] The fatigue crack monitoring performance verification system of the switch rail breakage monitoring system of the present invention comprises: 1 a switch rail breakage monitoring system, 2 a fatigue testing machine, 3 a full-scale test platform, 4 a strain acquisition device, 5 a video acquisition device, and 6 a flaw detection device.

[0071] The test rail 31 is assembled in the full-scale component 3 of the turnout. The switch sleeper 32 and the rail pad 33 both contain fastening components consistent with the on-site working conditions. The number of fasteners used can be flexibly adjusted according to the performance verification requirements. The test platform after the full-scale component 3 is assembled can be used for testing rail components such as base rails, point rails, and wing rails.

[0072] The generation and expansion of fatigue cracks originate from the fatigue testing machine 2 . The artificial defect 311 is set as the stress concentration point, and the crack expansion direction is controlled to be in the fatigue loading section 312 .

[0073] Fatigue crack detection uses online flaw detection equipment 6, and uses stress monitoring unit 4 and video monitoring unit 5 to judge and monitor the state of fatigue rail 31, so as to prevent missing the critical moment of crack expansion and record the moment of rail fracture in time.

[0074] During the first detection cycle, the alarm status of the monitoring system and the failure status of the first strain gauge 41 are simultaneously used as a basis for judgment to more fully monitor the growth status of the fatigue crack of the rail.

[0075] During the second detection cycle, the failure state of the second strain gauge is used as an auxiliary judgment basis to capture the fatigue crack growth process to the maximum extent, and the video monitoring unit is used to record the moment of rail fracture.

[0076] A comprehensive performance verification and analysis method divides the monitoring system into four evaluation levels: ① The monitoring system has the ability to identify cracks and can independently distinguish rail break events; ② The monitoring system has the ability to identify cracks but cannot independently distinguish rail break events; ③ The monitoring system does not have the ability to identify cracks but has the ability to identify rail break events; ④ The monitoring system does not have the ability to identify rail break events.

[0077] The performance verification method can be applied to the performance verification of most broken rail monitoring systems, and can also verify the crack monitoring capability of the monitoring system.

[0078] 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 fatigue crack monitoring capability verification system for a turnout broken rail monitoring system, characterized in that: include: Turnout broken rail monitoring system (1), fatigue testing machine (2), turnout full-scale fatigue component (3), strain acquisition equipment (4), video acquisition equipment (5) and flaw detection equipment (6); The switch broken rail monitoring system (1) is a monitoring system to be verified for performance, comprising a sensor (11), wherein the sensor (11) is installed on a test rail (31) and is used for collecting rail monitoring signals; The fatigue testing machine (2) is a load source for crack expansion, and can set the loading force, load ratio and loading frequency of the fatigue test, and can automatically unload the load after the loading cycle is completed; The turnout full-scale assembly (3) is laid on a test platform, and the turnout full-scale assembly (3) includes a test rail (31), a turnout sleeper (32) and a rail pad (33). The turnout sleeper (32) and the rail pad (33) both include fastening components consistent with on-site working conditions, and the number of fastening components used is flexibly adjusted according to performance verification requirements. An artificial defect (311) is made on the test rail (31) as a stress concentration point during the loading process, and the rail section where the stress concentration point is located is a stress concentration section (312). A fatigue testing machine (2) is set at the stress concentration section (312) to perform cyclic loading on the test rail (31) on the full-scale fatigue component (3) of the turnout. As the number of cyclic loading increases, fatigue cracks will extend upward from the stress concentration point along the stress concentration section; The strain acquisition device (4) monitors the rail strain of the test rail (31), and the stress monitoring value obtained is used as a judgment index of the crack extension state to select a suitable flaw detection method; the video acquisition device (5) is used to monitor the fracture state of the test rail (31) to assist in verifying the ability to judge the fracture state; Rail fatigue crack detection uses a flaw detection device (6) to measure the crack extension length during the crack propagation process.

2. The fatigue crack monitoring capability verification system of the turnout broken rail monitoring system according to claim 1, characterized in that: The test platform after the full-scale turnout assembly (3) is assembled can be used for testing rail components such as base rails, point rails, and wing rails. When the test rail is a movable rail component such as a point rail and a heart rail, it should be assembled according to the use conditions of its components. In addition to the test rail (31), the base rail is also installed to assist in fixing the test rail.

3. The fatigue crack monitoring capability verification system of the turnout broken rail monitoring system according to claim 1, characterized in that: The position of the artificial defect (311) is set at the rail bottom by default, and can be set at the rail head, rail waist or rail bottom according to performance verification requirements, and the corresponding setting positions of the first strain gauge (41) and the second strain gauge (42) of the strain acquisition device (4) are also adjusted accordingly.

4. The fatigue crack monitoring capability verification system of the turnout broken rail monitoring system according to claim 3, characterized in that: The artificial defect (311) is arranged at the bottom of the rail; the strain collection device (4) comprises a first strain gauge (41) and a second strain gauge (42), wherein the first strain gauge (41) is arranged directly below the artificial defect (311) at the bottom of the rail, and the second strain gauge (42) is arranged at a position below the bottom of the rail close to the artificial defect.

5. The fatigue crack monitoring capability verification system of the turnout broken rail monitoring system according to claim 4, characterized in that: The strain acquisition device (4) further comprises a third strain gauge (41) and a fourth strain gauge (42), wherein the third strain gauge (43) is arranged at a projection position of the rail head centerline below the rail bottom, and the fourth strain gauge (44) is arranged on a side of the rail bottom without artificial defects.

6. A method for verifying the crack monitoring capability of a switch rail breakage monitoring system, using the fatigue crack monitoring performance verification system for a switch rail breakage monitoring system according to any one of claims 1 to 5, the main steps being: S0, test rail assembly, laying a full-scale turnout assembly (3) on the fatigue test platform, and installing the turnout broken rail monitoring system (1) to be verified on the test rail (31); S1, cyclic loading of the rail, making an artificial defect (311) on the test rail (31) as a stress concentration point during the loading process, the rail section where the stress concentration point is located is the stress concentration section (312), using a fatigue testing machine (2) to set specific loading parameters to cyclically load the test rail (11) on the full-scale turnout assembly (3) at the stress concentration section (312); S2, rail strain monitoring, using strain acquisition equipment (4) to monitor the state of the test rail (31), and the obtained stress monitoring value is used as a judgment indicator of the crack propagation state to select a suitable flaw detection method; S3, video monitoring, during the cyclic loading process, a video acquisition device (5) is used to record the cyclic loading process of the test rail. The video acquisition device has a storage function and can determine the specific time when a specific rail state occurs, thereby realizing the monitoring of the cyclic loading state of the test rail and obtaining the specific time when the rail breaks; S4, rail fatigue crack detection, using flaw detection equipment (6) to measure the crack extension length during the crack propagation process; S5, performance verification analysis, compares the crack extension length obtained by flaw detection measurement with the alarm status of the monitoring system at the corresponding length to verify the monitoring performance of the monitoring system for fatigue cracks and broken rail conditions.

7. The method for verifying crack monitoring capability of a turnout broken rail monitoring system according to claim 6, wherein: The turnout broken rail monitoring system (1) remains in working condition during the entire performance verification process until the test rail is fatigue-broken.

8. The method for verifying crack monitoring capability of a turnout broken rail monitoring system according to claim 7, wherein: The full-scale turnout assembly (3) can be a single basic rail assembly, a base and point rail assembly, or a complete set of switch or frog assemblies; when the assembly is laid, the sleeper spacing and the sub-rail foundation are set according to the on-site laying conditions, and the sub-rail foundation can be a ballasted track bed or a ballastless track bed.

9. The method for verifying crack monitoring capability of a turnout broken rail monitoring system according to claim 6, wherein: In step S3, when collecting strain, at least the strain values of the rail on and near the damage are collected. As the rail crack expands, the strain value will gradually increase. When the strain gauge on the damage exceeds the limit and fails, the crack generally enters the expansion stage. At this time, closer attention should be paid to the alarm status of the monitoring system, and the rail should be inspected in a timely manner to determine the crack expansion status.

10. The method for verifying crack monitoring capability of a turnout broken rail monitoring system according to claim 6, wherein: In step S4, after the cyclic loading begins, the first detection cycle begins. When the monitoring system issues an alarm, the loading should be immediately suspended, and fatigue damage detection should be performed on the test rail. The detection position is located near the prefabricated damage. If the fatigue crack expands, the crack length L detected at this time and the alarm status of the monitoring system are recorded. If the system does not issue an alarm but the first strain gauge fails, the test loading is suspended, and fatigue damage detection is performed on the test rail. If crack expansion occurs, the crack length L is recorded. If crack expansion does not occur, the cyclic loading is continued for 50,000 times. After suspending the loading, fatigue crack detection is performed and the crack length L is recorded until L ≥ 10 mm. The loading is then suspended, and the first detection cycle ends. After the first detection cycle ends, the second detection cycle begins, and loading continues. After 30,000 cycles of loading, loading is suspended, fatigue crack detection is performed, and the crack length L and the alarm status of the monitoring system are recorded. When L ≥ 15 mm, loading is continued until the test rail breaks. When L < 15 mm, fatigue testing is continued for 30,000 times, loading is suspended, and fatigue crack detection is performed until L ≥ 15 mm. Loading is continued until the rail breaks, and loading ends.

11. The method for verifying crack monitoring capability of a turnout broken rail monitoring system according to claim 6, wherein: In step S5, when the monitoring system issues an initial alarm, the crack detection record at the time of the alarm is checked. If the crack expands and the monitoring system continues to alarm, the crack detection sensitivity of the monitoring system is the crack length L0 at the time of the initial alarm. If the crack expands and the monitoring system does not continue to alarm, it is determined that the monitoring system has missed an alarm. If the crack does not expand when the monitoring system initially alarms, it is determined that the monitoring system has a false alarm. After a false alarm occurs in the monitoring system, its false alarm status is determined. If the false alarm does not occur continuously and a continuous alarm begins to be issued during the crack propagation process, the crack monitoring sensitivity of the monitoring system is the crack length L1 when the continuous alarm is issued; if the false alarm status persists, the monitoring system does not have the crack monitoring capability; and if the monitoring system does not issue a continuous alarm during the crack propagation process, the monitoring system does not have the crack monitoring capability.

12. The method for verifying crack monitoring capability of a turnout broken rail monitoring system according to claim 11, wherein: The broken rail monitoring capability of the monitoring system shall be judged. At this time, the specific moment of rail breakage shall be confirmed through the stress monitoring unit and the video monitoring unit. When the monitoring system has the crack monitoring capability, if the rail breaks, the monitoring system can issue a higher level alarm, and the monitoring system can distinguish the broken rail event separately. If it is not possible to issue a higher level alarm when the rail breaks, the monitoring system cannot distinguish the broken rail event separately. The higher level alarm determination can be based on the alarm logic of the monitoring system to be verified. If the alarm level is not distinguished in the alarm logic, but there is a separate broken rail alarm mark, and it is triggered when the rail breaks, then the alarm status at this time should be equivalently determined to be a higher level alarm. When the monitoring system does not have the crack monitoring capability, if the monitoring system can issue a higher level alarm or a separate broken rail alarm mark when the rail breaks, then the monitoring system has the broken rail monitoring capability.

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