A micro device and method for automated monitoring of long-term settlement of railway tracks

Abstract

The application discloses a kind of micro device and method for long-term settlement of railway track is monitored automatically, comprising: first settlement monitoring module is arranged at each measuring point, and second settlement monitoring module is arranged at reference point;Data acquisition and analysis module is used to obtain the spectral data of first settlement monitoring module and second settlement monitoring module, and the settlement of railway track is calculated according to the liquid level change difference of measuring point and reference point;Wherein, first settlement monitoring module includes: fixed support, the fixed support is C type, the upper end is fixed to the upper surface of the edge of sleeper, and the lower end is free plane;First micro-fiber grating static level gauge is installed above the free platform of fixed support;Protective sleeve, the protective sleeve is hollow, placed outside fixed support, and the lower part is buried in ballast layer to ensure the vertical free movement of first micro-fiber grating static level gauge;Wherein, second settlement monitoring module includes: second micro-fiber grating static level gauge.

Description

Technical Field

[0001] This application relates to the field of railway track technology, and in particular to a miniature device and method for automatically monitoring long-term settlement of railway tracks. Background Technology

[0002] High-speed railway track structures are divided into two types: ballastless track and ballasted track. Ballastless track is mainly used in high-speed railways with a design speed of 300 km / h and above, while ballasted track is mostly used in low-speed passenger or freight railways. The main structure of ballasted track, from top to bottom, consists of rails, fasteners, sleepers, ballast layer, bottom ballast layer, embankment, and foundation. Under the cyclic dynamic load of trains, both the ballast bed and the subgrade soil will undergo irreversible plastic deformation, resulting in uneven track surfaces that affect passenger comfort and train operation safety. Furthermore, the intensified wheel-rail dynamic interaction further accelerates the cumulative settlement of ballasted track. Therefore, it is necessary to monitor and predict the settlement trend of ballasted track to promptly understand the operational status of the railway line.

[0003] In past railway field tests, traditional settlement monitoring technologies such as fixed plates, observation piles, and settlement gauges were commonly used. While convenient and low-cost, these technologies are highly susceptible to environmental influences, have low durability, and incur high labor costs, often failing to meet the accuracy and long-term requirements of settlement monitoring. Static levels monitor liquid level changes at measuring points based on the principle of communicating vessels, often utilizing magnetostriction, ultrasonic waves, and pressure changes to determine liquid level height, enabling online automatic settlement measurement. However, their large overall size limits their application to settlement monitoring in open areas such as railway slopes. Fiber Bragg grating static levels integrate the simple principles of static levels with the photosensitivity of fiber optic gratings. They calculate settlement changes at measuring points by utilizing changes in the wavelength of reflected waves, offering advantages such as high accuracy, small size, light weight, and ease of installation. However, the railway service environment is complex. To ensure train operation safety, especially high-speed train operation safety, extremely high requirements are placed on the stability of the track structure, and even more stringent standards and requirements are imposed on foreign objects outside the track. For example, due to the needs of track operation and testing, the height of sensors on the track must not exceed the height of the rails (or be less than 176mm), and they must meet requirements such as high durability and a high degree of automation to reduce personnel on-line maintenance and avoid impacting train safety and efficient operation. To date, there is still no efficient and reliable means for automated monitoring of long-term track settlement.

[0004] Therefore, in order to achieve long-term monitoring of the overall settlement of railway tracks and reduce the interference of sensor installation on the railway site, it is an urgent settlement monitoring method to be implemented and verified by using a miniature fiber optic static level and equipping it with a complete device scheme to directly deploy it on the track surface. Summary of the Invention

[0005] The purpose of this application is to provide a miniature device and method for automatically monitoring long-term settlement of railway tracks, thereby mitigating the problems of difficult installation, low accuracy, and poor durability of existing technologies at railway sites, and realizing long-term monitoring of the overall settlement of ballasted tracks and conducting long-term serviceability assessment of railway lines.

[0006] According to a first aspect of the embodiments of this application, a miniature device for automatically monitoring long-term settlement of railway tracks is provided, comprising:

[0007] The first settlement monitoring module is deployed at each measuring point, and the second settlement monitoring module is deployed at the reference point;

[0008] The data acquisition and analysis module is used to acquire spectral data collected by the first settlement monitoring module and the second settlement monitoring module, and calculate the difference between the liquid level change at the measuring point and the liquid level change at the reference point based on the spectral data, so as to judge the settlement of the railway track in real time.

[0009] The first settlement monitoring module includes:

[0010] The first miniature fiber optic grating hydrostatic level has an embedded measuring fiber and a temperature-compensating fiber. It obtains the liquid level difference by the change of the center wavelength of the fiber and is used to measure the cumulative settlement of the track structure.

[0011] A fixed bracket, which is C-shaped, has its upper plane fixed to the upper surface of the edge of the sleeper, and its lower plane is a free end; a fixed base is placed on the lower plane of the fixed bracket for fixing the first miniature fiber optic grating hydrostatic level.

[0012] The protective sleeve is a hollow iron barrel, placed outside the fixed support, with its lower end embedded in the ballast layer to ensure the vertical free movement of the first miniature fiber optic grating static level.

[0013] The second settlement monitoring module includes a second miniature fiber optic grating hydrostatic level.

[0014] According to a second aspect of the embodiments of this application, a method for automatically monitoring long-term settlement of railway tracks is provided. This method is implemented based on the aforementioned apparatus and specifically includes the following steps:

[0015] Clean the ballast particles from the edge of the sleeper to a depth equal to the sum of the height of the fixed support and the range of the first miniature fiber optic static level.

[0016] Place a protective sleeve, ensuring that the top of the second sleeve wall is equal to or slightly higher than the sleeper surface;

[0017] Drill holes along the edge of the sleeper. The diameter of the drilled holes should be the same as the first positioning hole on the long side (upper end) of the fixed bracket.

[0018] The first miniature fiber optic static level was welded securely to the base. The third positioning hole on the base was aligned with the second positioning hole pre-set on the short side of the bracket, and expansion bolts were driven in to secure it.

[0019] The fixed bracket, the built-in first miniature fiber optic static level, and the fixed base are placed together in the protective sleeve. Align the reserved holes on the sleeper and the first positioning hole at the upper end of the fixed bracket, and drive in the expansion bolts to fix them.

[0020] A second miniature fiber optic grating static level and a water tank are set up on an independent platform at the edge of the line. The difference between the elevation of the two (the elevation of the independent platform) and the elevation of each first miniature fiber optic grating static level is no greater than the range of the level. A demodulator is placed inside the chassis.

[0021] Each first miniature fiber optic grating static level and a second miniature fiber optic grating static level located at the reference point are coupled through a vent pipe, a liquid inlet pipe, and a communication optical cable; the vent pipe and liquid inlet pipe of the second miniature fiber optic grating static level are connected to a water tank, and the communication optical cable is connected to a demodulator.

[0022] Fill the water tank with antifreeze, and then fill and defoam.

[0023] The data acquisition and analysis module records the wavelength change caused by the liquid level change and detects the relative sedimentation of the measuring point in real time. The relative sedimentation of the measuring point is the difference between the liquid level change of the measuring point and the liquid level change of the reference point at the same time.

[0024] The technical solutions provided by the embodiments of this application may include the following beneficial effects:

[0025] As can be seen from the above embodiments, this application overcomes the technical bottlenecks of traditional static levels, such as large size, difficult installation on railway sites, and significant impact from train vibration, by using a miniature fiber optic grating static level to monitor the cumulative settlement of ballasted track bed and subgrade structure. Utilizing the small size of the miniature static level reduces the complexity of sensor installation, minimizes the impact of construction on the ballast structure to ensure the integrity of the track bed structure, and also reduces level reading errors caused by train vibration loads and environmental loads. Because the level is placed below the edge of the sleeper, a fixed base and support are designed, greatly reducing construction difficulty. No track maintenance or rail lifting is required; only the removal of some ballast particles from the sleeper edge and connection of the fixing device to the sleeper are needed to achieve cumulative settlement monitoring. This overcomes the problem that traditional measurement methods may interfere with safe train operation on actual railway sites, eliminating threats to train safety.

[0026] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0027] Figure 1 This is a three-dimensional schematic diagram of a hydrostatic level, a fixed support, a fixed base, and a protective device in a miniature device and method for automatically monitoring long-term settlement of railway tracks, according to an exemplary embodiment.

[0028] Figure 2 This is a side view of an overall device for automatically monitoring long-term settlement of railway tracks, according to an exemplary embodiment.

[0029] Figure 3 This is a side view illustrating the application of a miniature device and method for automating the monitoring of long-term settlement of railway tracks in field testing, according to an exemplary embodiment.

[0030] Figure 4 This is a schematic diagram of sleeper measuring point markings during an experiment of a miniature device and method for automatically monitoring long-term settlement of railway tracks, according to an exemplary embodiment.

[0031] The attached diagrams are labeled as follows: rail-1, sleeper-2, ballast layer-3, embankment-4, foundation-5, fixed bracket-6, fixed base-7, first miniature fiber optic grating static level-8, protective sleeve-9, second miniature fiber optic grating static level-10, water tank-11, demodulator-12, computer-13, wireless network-14, vent pipe-15, liquid pipe-16, communication optical cable-17, network cable-18, first positioning hole-19, third positioning hole-20, first cylinder wall-21, second cylinder wall-22. Detailed Implementation

[0032] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0033] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0034] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0035] like Figures 1-4 As shown, this embodiment of the invention provides a first settlement monitoring module deployed at each measuring point for automated monitoring of long-term settlement of railway tracks, and a second settlement monitoring module deployed at a reference point.

[0036] The data acquisition and analysis module is used to acquire spectral data collected by the first settlement monitoring module and the second settlement monitoring module, and calculate the difference between the liquid level change at the measuring point and the liquid level change at the reference point based on the spectral data, so as to judge the settlement of the railway track in real time.

[0037] The first settlement monitoring module includes:

[0038] The first miniature fiber optic grating hydrostatic level 8 has embedded measuring fiber and temperature compensation fiber. It obtains the liquid level difference by changing the center wavelength of the fiber and is used to measure the cumulative settlement of the track structure.

[0039] The fixed base 7 is welded to the bottom of the first miniature fiber optic grating static level 8 to form a whole.

[0040] The fixed bracket 6 is C-shaped, with its upper end plane fixed to the upper surface of the edge of the sleeper 2 and its lower end plane being a free end; a fixed base 7 is placed on the lower end plane of the fixed bracket 6 for fixing the first miniature fiber optic grating static level 8.

[0041] The protective sleeve 9 is a hollow iron barrel, placed outside the fixed bracket 6, with its lower end embedded in the ballast layer 3 to ensure the vertical free movement of the first micro fiber optic static level 8.

[0042] The second settlement monitoring module includes a second miniature fiber optic grating hydrostatic level 10 and a water tank 11.

[0043] Furthermore, the dimensions of the first miniature fiber optic static level 8 installed at each measuring point and the second miniature fiber optic static level 10 installed at the benchmark point are: length 105 mm, width 105 mm, height 42 mm, which are significantly lower than the sleeper height (Type II 145 mm) and ballast layer thickness (generally 300 mm).

[0044] As can be seen from the above embodiments, this application overcomes the technical bottlenecks of traditional static levels, such as large size, difficulty in installation at railway sites, and significant impact from train vibration, by using a miniature fiber optic grating static level to monitor the cumulative settlement of ballasted track bed and subgrade structure. This minimizes the impact of the sensor on the ballast structure and reduces reading errors. Because the level is placed below the edge of the sleeper, a fixed base and support are designed, greatly reducing construction difficulty. No track maintenance or rail lifting is required; only the removal of some ballast particles from the sleeper edge is needed to monitor the cumulative settlement of the railway line. This overcomes the problem of traditional measurement methods potentially interfering with safe train operation at railway sites and eliminates threats to train safety.

[0045] Furthermore, the upper plane of the fixed bracket 6 is the long side, and the lower plane is the short side; the lower plane of the fixed bracket 6 is a free plane with a second positioning hole, and the fixed base 7 has a third positioning hole 20. By aligning the second positioning hole and the third positioning hole 20 with expansion bolts, the fixed base 7 is fixed on the lower plane of the fixed bracket 6, thereby fixing the first miniature fiber optic grating hydrostatic level 8 on the lower plane of the fixed bracket 6.

[0046] Furthermore, the upper end plane of the fixed bracket 6 is provided with a first positioning hole 19, through which the fixed bracket 6 is fixed to the edge of the sleeper 2; the width of the upper end plane of the fixed bracket 6 needs to ensure a stable connection with the sleeper 2, and the distance between the fixed bracket 6 and the outer edge of the sleeper 2 can accommodate the slight lateral displacement of the sleeper 2.

[0047] Furthermore, the protective sleeve 9 is a hollow iron barrel with openings at both the top and bottom, placed outside the fixed bracket 6. It is surrounded by a first cylindrical wall 21 near the side of the sleeper 2 and three other second cylindrical walls 22 of equal height; wherein, the height of the first cylindrical wall 21 is lower than that of the second cylindrical walls 22.

[0048] Furthermore, the height of the second cylindrical wall 22 is greater than the sum of the height of the fixed support 6 and the range of the first miniature fiber optic grating static level 8; the height difference between the first cylindrical wall 21 and the second cylindrical wall 22 should be greater than the height of the fixed support 6, so as to ensure that the first miniature fiber optic grating static level 8 can move freely within its range.

[0049] In this embodiment of the invention, the device may further include: a water tank 11, which, together with the second settlement monitoring module deployed at the reference point, is deployed on an independent platform near the railway track, and the liquid level difference between the water tank 11 and each of the first miniature fiber optic grating static level 8 and the second miniature fiber optic grating static level 10 does not exceed the range of the first miniature fiber optic grating static level 8; the water tank 11 is filled with antifreeze; the antifreeze replaces water as the liquid in the connection system of the first miniature fiber optic grating static level 8 and the second miniature fiber optic grating static level 10, ensuring the normal operation of the instruments under low temperature conditions.

[0050] like Figure 2 As shown in the embodiment of the present invention, the device may further include: a first miniature fiber optic grating static level 8 deployed at each measuring point, and a second miniature fiber optic grating static level 10 deployed at a reference point, which are coupled to each other via a vent pipe 15, a liquid inlet pipe 16, and a communication optical cable 17, respectively; the second miniature fiber optic grating static level 10 is also connected to a demodulator 12 via the communication optical cable 17; the vent pipe 15 is used to keep the pressure above the liquid surface in the container of each first miniature fiber optic grating static level 8 and / or second miniature fiber optic grating static level 10 constant; the liquid inlet pipe 16 is used to keep the liquid in each first miniature fiber optic grating static level 8 and / or second miniature fiber optic grating static level 10 at the same horizontal level under the action of atmospheric pressure and gravity; the communication optical cable 17 is used to remotely transmit optical signals based on total internal reflection.

[0051] In this embodiment of the invention, the device may further include: thermal insulation cotton for wrapping the water tank 11, the first miniature fiber optic static level 8 installed on the edge of the sleeper, and the second miniature fiber optic static level 10 installed at the reference point; galvanized steel pipe for wrapping the ventilation pipe 15, liquid pipe 16, and communication optical cable 17 that need to cross the railway line to prevent the water, air, and communication lines from being damaged by the ballast; and PVC pipe for wrapping the ventilation pipe 15, liquid pipe 16, and communication optical cable 17 exposed in other locations to prevent the water, air, and communication lines from being damaged.

[0052] On the other hand, such as Figure 3 As shown in the figure, this embodiment of the invention also provides a method for automatically monitoring long-term settlement of railway tracks. This method is implemented in the device described above and specifically includes the following steps:

[0053] (1) Before installation, the ballast particles on the edge of the test sleeper should be removed in advance, and the ballast layer 3 should be excavated. The excavation depth should be greater than the sum of the height and range of the static level. At the same time, the sleeper should be drilled. The diameter of the drill hole should be consistent with the size of the opening at the top of the fixed bracket.

[0054] Specifically, in this example, such as Figure 3As shown, the railway line structure, from top to bottom, includes rails 1, sleepers 2, ballast layer 3, embankment 4, and foundation 5. During on-site testing, sleepers for measurement are pre-selected. During the maintenance window, ballast particles are removed from the outer edge of the test sleepers, with the removal depth exceeding the sum of the height and range of the static level 10. Simultaneously, holes are drilled on the test sleepers 2 according to the diameter and spacing of the first positioning holes 19 on the fixed bracket 6.

[0055] (2) Place a protective sleeve 9 on the outer edge of the sleeper after cleaning, and make the top of the second sleeve wall 22 equal to or slightly higher than the sleeper surface;

[0056] (3) Weld the bottom of the first micro fiber grating static level 8 to the fixed base 7 firmly, and connect the second positioning hole on the fixed bracket and the third positioning hole 20 on the fixed base with bolts.

[0057] (4) Align the first positioning hole 19 on the fixed bracket with the reserved hole on the edge of the sleeper, and fix it with expansion bolts, that is, place the static level and the fixing device on the edge of the sleeper.

[0058] (5) Fix the second miniature fiber optic static level 10 and the water tank 11, which are set up at the benchmark point, on an independent foundation near the line. The height difference between the two and the height difference between them and the sensor at the test point shall not exceed the range.

[0059] (6) Each first miniature fiber optic grating static level 8 and the second miniature fiber optic grating static level 10 located at the reference point are coupled through an air pipe 15, a liquid pipe 16, and a communication optical cable 17. The air pipe 15 and liquid pipe 16 of the second miniature fiber optic grating static level 10 are connected to the water tank 11, and the communication optical cable 17 is connected to the demodulator. The demodulator 12 is connected to the computer 13 through a network cable 18, and the computer 13 is connected to the wireless network 14.

[0060] (7) Inject antifreeze into the water tank to fill and remove bubbles.

[0061] Specifically, in this example, such as Figure 4 As shown, to reduce testing errors, three test sleepers were selected. The static level on the three sleepers should form a path with the benchmark point. The air vent, liquid vent, and communication fiber optic cable on the static level are connected using vent pipe 15, liquid vent pipe 16, and communication fiber optic cable 17 to establish air, water, and signal paths. After wiring, liquid filling and defoaming are performed. First, the vent pipes 17 of the two levels in the middle of the path are temporarily blocked. Then, sufficient antifreeze is poured into the water tank 11, with the water level above the vent pipe, ensuring the antifreeze fills the end level and flows smoothly out of its vent pipe. Then, the vent pipe of the end level is blocked, and the temporary plugs on the vents of all equipment in the middle section are removed. The system is left to stand for a period of time to allow the liquid levels of all equipment to reach equilibrium.

[0062] (8) After the communication vessel is formed, install protective devices to protect the pipelines and equipment.

[0063] Specifically, excessive temperature differences can cause the liquid inside the instrument to expand and contract due to temperature changes, leading to measurement errors. Encasing the hydrostatic level with insulating cotton protects the equipment and provides thermal insulation. To prevent damage to exposed communication cables, the fiber optic cable is threaded through a PVC conduit. The area between the PVC conduit and the level is then secured with a corrugated flexible metal tube with a plastic sheath.

[0064] (9) To obtain the long-term settlement of the ballasted track structure, wavelength data (including liquid level wavelength and temperature compensation wavelength) at times when no trains pass through are selected as measurement samples on a daily basis via remote terminal operation; at the same time, the sample at the start of recording (after the level instrument is installed) is used as the initial measurement value, and the liquid level change (D) is calculated by combining the daily wavelength and the initial wavelength. The calculation formula is as follows:

[0065] ]

[0066] in, (mm / mm) is the proportionality coefficient between the liquid level and the change in wavelength. The temperature compensation coefficient for wavelength change is given; both parameters are obtained through factory calibration. (nm) represents the measured wavelength of the liquid level. (nm) represents the initial measured value of the liquid level wavelength. (nm) represents the temperature-compensated wavelength measurement value. This is the initial measurement value for the temperature-compensated wavelength.

[0067] (10) The cumulative settlement of the track bed structure at the measuring point causes a drop in the liquid level and an increase in the water volume of the first miniature fiber optic grating static level 8, which in turn causes a decrease in the water volume of the second miniature fiber optic grating static level 10 at the benchmark point. Therefore, in order to obtain the relative settlement (S) at the measuring point, the change in liquid level (D) at the measuring point is used to determine the relative settlement (S) at the measuring point. B ) and the change in liquid level at the reference point at the same time (D) T Subtract from each other. Calculation formula:

[0068] S = D T – D B

[0069] This invention utilizes a miniature fiber optic grating hydrostatic level to monitor the long-term settlement of ballasted tracks, mitigating the problems of existing monitoring methods such as difficult installation, low accuracy, and poor durability at railway sites. It also minimizes the impact of sensors on the ballast structure and improves reading accuracy.

[0070] Because the level instrument is placed below the edge of the sleeper, there is no need for the track maintenance department to lift the track. Only some ballast particles on the edge of the sleeper need to be removed to achieve cumulative settlement monitoring, which reduces the problem of interfering with the safe operation of trains and eliminates the threat to the safe operation of trains.

[0071] In summary, this device utilizes a miniature fiber optic grating hydrostatic level as a monitoring sensor. By installing a fixed base and support, it can be positioned below the edge of the sleeper, enabling long-term monitoring of the overall settlement of ballasted track and thus conducting service performance evaluation while minimizing on-site damage. This method and device are suitable for studying the cumulative settlement development law of railway ballasted track under train operating loads and can also provide relevant technical support for the on-site installation and construction of similar sensors in railways.

[0072] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0073] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A miniature device for automatically monitoring long-term settlement of railway tracks, characterized in that, include: The first settlement monitoring module is deployed at each measuring point, and the second settlement monitoring module is deployed at the reference point; The data acquisition and analysis module is used to acquire spectral data collected by the first settlement monitoring module and the second settlement monitoring module, and calculate the difference between the liquid level change at the measuring point and the liquid level change at the reference point based on the spectral data, so as to judge the settlement of the railway track in real time. The first settlement monitoring module includes: The first miniature fiber optic static level (8) has embedded measuring fiber and temperature compensation fiber. The liquid level difference is obtained by the change of the center wavelength of the fiber and is used to measure the cumulative settlement of the track structure. Fixed bracket (6), the fixed bracket (6) is C-shaped, its upper end plane is fixed to the upper surface of the edge of the sleeper (2), and its lower end plane is a free end; a fixed base (7) is placed on the lower end plane of the fixed bracket (6) for fixing the first micro fiber optic grating static level (8). The protective sleeve (9) is a hollow iron barrel placed outside the fixed bracket (6), with its lower end embedded in the ballast layer (3) to ensure the vertical free movement of the first micro fiber optic grating static level (8). The second settlement monitoring module includes: a second miniature fiber optic grating hydrostatic level (10).

2. A miniature device for automatically monitoring long-term settlement of railway tracks according to claim 1, characterized in that, The dimensions of the first miniature fiber optic static level (8) installed at each measuring point and the second miniature fiber optic static level (10) installed at the reference point are: length 105 mm, width 105 mm, and height 42 mm.

3. A miniature device for automatically monitoring long-term settlement of railway tracks according to claim 1, characterized in that, The upper plane of the fixed bracket (6) is the long side, and the lower plane is the short side; the lower plane of the fixed bracket (6) has a second positioning hole, and the fixed base (7) has a third positioning hole (20). The fixed base (7) is fixed to the lower plane of the fixed bracket (6) through the second positioning hole and the third positioning hole (20), thereby fixing the first miniature fiber optic static level (8) to the lower plane of the fixed bracket (6); The upper end plane of the fixed bracket (6) has a first positioning hole (19), through which the fixed bracket (6) is fixed to the edge of the sleeper (2); the width of the upper end plane of the fixed bracket (6) needs to ensure a stable connection with the sleeper (2), and the outer extension distance of the fixed bracket (6) can accommodate the slight lateral displacement of the sleeper (2).

4. A miniature device for automatically monitoring long-term settlement of railway tracks according to claim 1, characterized in that, The protective sleeve (9) is a hollow iron barrel with openings at both the top and bottom, placed outside the fixed bracket (6); it is surrounded by a first cylindrical wall (21) on the side closest to the sleeper (2) and a second cylindrical wall (22) of equal height on the other three sides; wherein, the height of the first cylindrical wall (21) is lower than that of the second cylindrical wall (22). The height of the second cylinder wall (22) is greater than the sum of the height of the fixed bracket (6) and the range of the first micro fiber optic grating static level (8); the height difference between the first cylinder wall (21) and the second cylinder wall (22) should be greater than the height of the fixed bracket (6) to ensure that the first micro fiber optic grating static level (8) can move freely within its range.

5. A miniature device for automatically monitoring long-term settlement of railway tracks according to claim 1, characterized in that, The device further includes a water tank (11), which and the second settlement monitoring module located at the reference point are jointly located on an independent platform near the railway track. The liquid level difference between the water tank (11) and each of the first micro fiber grating hydrostatic level (8) and the second micro fiber grating hydrostatic level (10) does not exceed the range of the first micro fiber grating hydrostatic level (8). The water tank (11) is filled with antifreeze.

6. A miniature device for automatically monitoring long-term settlement of railway tracks according to claim 1, characterized in that, The device further includes: a first miniature fiber optic grating static level (8) installed at each measuring point, and a second miniature fiber optic grating static level (10) installed at a reference point, which are coupled to each other via an air pipe (15), a liquid pipe (16) and a communication optical cable (17); the second miniature fiber optic grating static level (10) is also connected to a demodulator (12) via a communication optical cable (17); The vent pipe (15) is used to keep the pressure above the liquid level in the container of each first micro fiber grating hydrostatic level (8) and / or second micro fiber grating hydrostatic level (10) constant; The liquid passage (16) is used to keep the liquid in each of the first micro fiber grating hydrostatic level (8) and / or the second micro fiber grating hydrostatic level (10) at the same level under the action of atmospheric pressure and gravity. The communication optical cable (17) is used to remotely transmit optical signals based on total internal reflection.

7. A miniature device for automatically monitoring long-term settlement of railway tracks according to claim 6, characterized in that, The device further includes: Thermal insulation cotton is used to wrap the water tank (11), the first miniature fiber optic grating static level (8) installed on the edge of the sleeper, and the second miniature fiber optic grating static level (10) installed at the reference point. Galvanized steel pipes are used to wrap ventilation pipes (15), liquid pipes (16), and communication optical cables (17) that need to cross railway lines to prevent waterways, gasways, and communication lines from being damaged by ballast. PVC pipes are used to wrap the exposed ventilation pipes (15), liquid pipes (16), and communication optical cables (17) to prevent damage to water, air, and communication systems.

8. A method for automatically monitoring long-term settlement of railway tracks, characterized in that, This method is implemented based on the apparatus according to any one of claims 1-7, and the method specifically includes the following steps: Clean the ballast particles from the edge of the sleeper (2) to a depth equal to the sum of the height of the fixed support (6) and the range of the first micro fiber optic static level (8). Place the protective sleeve (9) so that the top of the second sleeve wall (22) is equal to or slightly higher than the surface of the sleeper (2); Drill holes on the edge of the sleeper (2), and the hole diameter should be the same as the first positioning hole (19) on the long side (upper end) of the fixed bracket (6); The first miniature fiber optic static level (8) is welded firmly to the fixed base (7), the third positioning hole (20) on the fixed base (7) and the second positioning hole preset on the short side of the fixed bracket (6) are aligned, and expansion bolts are driven in to fix it. Place the fixed bracket (6), the first miniature fiber optic static level (8) and the fixed base (7) together inside the protective sleeve (9), align them with the reserved holes on the sleeper and the first positioning hole (19) at the upper end of the fixed bracket (6), and drive in expansion bolts to fix them; A second miniature fiber optic grating static level (10) and a water tank (11) are arranged on an independent platform at the edge of the line. The elevation difference between the two and the elevation difference between each first miniature fiber optic grating static level (8) is not greater than the range of the level. A demodulator (12) is placed inside the chassis. Each first miniature fiber optic grating static level (8) and a second miniature fiber optic grating static level (10) located at the reference point are coupled through a vent pipe (15), a liquid pipe (16), and a communication optical cable (17); the vent pipe (15) and liquid pipe (16) of the second miniature fiber optic grating static level (10) are connected to the water tank (11), and the communication optical cable (17) is connected to the demodulator (12); Fill the water tank (11) with antifreeze and perform filling and defoaming. The data acquisition and analysis module records the wavelength change caused by the liquid level change and detects the relative sedimentation of the measuring point in real time. The relative sedimentation of the measuring point is the difference between the liquid level change of the measuring point and the liquid level change of the reference point at the same time.

9. A method for automatically monitoring long-term settlement of railway tracks according to claim 8, characterized in that, The calculation process for liquid level change includes: Define the detection frequency and periodically acquire wavelength data at times when no trains pass by. The wavelength data includes liquid level wavelength and temperature-compensated wavelength. Acquire the wavelength data corresponding to the installation of the first miniature fiber optic level (8) and / or the second miniature fiber optic level (10) as the initial wavelength. Calculate the liquid level change based on the wavelength data corresponding to each detection cycle and the initial wavelength, as shown in the following expression: ; in, This is the proportionality coefficient between the liquid level and the change in wavelength. This is the temperature compensation coefficient for the wavelength change; This is the measured value of the liquid level wavelength. This is the initial measured value of the liquid level wavelength. This is the temperature-compensated wavelength measurement value. This is the initial measurement value for the temperature-compensated wavelength.

10. A method for automatically monitoring long-term settlement of railway tracks according to claim 8, characterized in that, The cumulative settlement of the track bed structure at the measuring point causes a drop in the liquid level and an increase in the water volume of the first micro fiber grating static level (8), which in turn causes a decrease in the water volume of the second micro fiber grating static level (10) at the benchmark point. Therefore, to obtain the relative settlement at the measuring point, the change in liquid level of the first micro fiber grating static level (8) is subtracted from the change in liquid level of the second micro fiber grating static level (10) at the same time. Calculation formula: S = D T – D B ; In the formula, S is the relative settlement of the measuring point, and D is the relative settlement of the measuring point. B D represents the liquid level change of the first miniature fiber optic hydrostatic level. T This represents the liquid level change of the second miniature fiber optic grating hydrostatic level.

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