Miniature device and method for automatically monitoring long-term settlement of railway track

Abstract

The invention discloses a miniature device and method for automatically monitoring long-term settlement of a railway track. The miniature device comprises a first settlement monitoring module arranged at each measuring point and a second settlement monitoring module arranged at a datum point, the data acquisition and analysis module is used for acquiring spectral data of the first settlement monitoring module and the second settlement monitoring module, and calculating railway track settlement according to a liquid level change difference value of a measuring point and a reference point; wherein the first settlement monitoring module comprises a C-shaped fixing support, the upper end of the fixing support is fixed on the upper surface of the edge of the sleeper, and the lower end of the fixing support is a free plane; the first micro fiber bragg grating static leveling instrument is mounted above the free platform of the fixed bracket; the protective sleeve is hollow and is arranged on the outer side of the fixed bracket, and the lower part of the protective sleeve is embedded into a railway ballast layer so as to ensure the vertical free movement of the first micro fiber grating static force level gauge; wherein the second settlement monitoring module comprises a second miniature fiber grating static level gauge.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of railway track, in particular to a micro device and method for automatically monitoring long-term settlement of railway track. BACKGROUND

[0002] The track structure in high-speed railway is divided into two types: ballastless track and ballasted track. Ballastless track is mainly used for high-speed railway designed for train speed of 300 km / h and above, and ballasted track is mainly used for low-speed passenger or freight railway. The main structure of ballasted track is composed of, from top to bottom, steel rail, fastener, sleeper, ballast layer, bottom ballast layer, embankment and foundation. Under the action of cyclic dynamic load of train, both the track bed and the roadbed soil will produce irreversible plastic deformation, which will lead to track surface irregularity and affect the comfort of passengers and the safety of train operation. At the same time, due to the intensification of wheel-rail dynamic interaction, the development of cumulative settlement of ballasted track is further accelerated. Therefore, it is necessary to monitor and predict the settlement of ballasted track to timely grasp the operation state of railway line.

[0003] In the past railway field test, traditional settlement monitoring technologies such as fixed plate, observation pile and settlement gauge are often used, which are convenient to operate and low in cost, but are greatly affected by environment, have low durability and high labor cost, and often cannot meet the accuracy and long-term requirements of settlement monitoring. The static level gauge monitors the change of liquid level of the measuring point according to the principle of connecting pipe, and uses the principles of magnetostriction, ultrasonic wave and pressure change to judge the liquid level height to realize online automatic settlement measurement. However, due to the large overall volume, it is often limited to the settlement monitoring application of open terrain such as railway slope. The fiber grating static level gauge integrates the simple principle of static level gauge and the photosensitive characteristics of fiber grating, and uses the change of reflected wave wavelength to calculate the settlement change of measuring point, which has the advantages of high precision, small volume, light weight and easy installation. However, the railway service environment is complex, and in order to ensure the safety of train operation, especially high-speed train operation, high stability of track structure is required, and more stringent standards and requirements are put forward for foreign matters outside the line. For example, the height of sensor on the track should not be higher than the height of steel rail (or less than 176 mm), and the sensor should meet the requirements of high durability, high automation and the like, so as to reduce the personnel maintenance on the line, affect the safety and efficient operation of train. So far, there is still no efficient and reliable means to automatically monitor the long-term settlement of track line.

[0004] Therefore, in order to realize long-term monitoring of the overall settlement of railway track and reduce the interference of sensor installation on the railway site, a micro fiber grating static level gauge is adopted, and a complete device scheme is provided to directly lay the gauge on the track surface, which is a settlement monitoring method that needs to be realized and verified. SUMMARY

[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, which is placed outside the fixed support, and its lower end is buried in the ballast layer to ensure the vertical free movement of the first micro fiber 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 on 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 automatically monitoring 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 grating 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 105mm, width 105mm, height 42mm, which are significantly lower than the sleeper height (Type II 145mm) and the ballast layer thickness (generally 300mm).

[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 located at the reference point, is located 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 static level 10 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 reference point static level 12 and the water tank 11 on an independent foundation near the line, and the height difference between the two and the height difference with the test point sensor shall not exceed the range.

[0059] (6) 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 via air pipe 15, liquid pipe 16, and 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 via 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-compensated wavelength) at times when no trains pass through are selected as measurement samples on a daily basis via remote terminal operation; simultaneously, 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 together with the daily wavelength and the initial wavelength. The calculation formula is as follows:

[0065] D=K λ *[(λ-λ0)-K T *(λ T -λ T0 )]

[0066] Where, K λ (mm / mm) is the proportionality coefficient between liquid level and wavelength change, K T λ is the temperature compensation coefficient for wavelength change; both parameters are obtained through factory calibration. λ(nm) is the measured value of the liquid level wavelength, and λ0(nm) is the initial measured value of the liquid level wavelength. T (nm) represents the temperature-compensated wavelength measurement value, λ T0 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 in the first miniature fiber optic grating static level 8, which in turn causes a decrease in the water volume in 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 and method 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 grating 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, which is used to measure the cumulative settlement of the track structure. A 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); The protective sleeve (9) is a hollow iron barrel placed outside the fixed bracket (6), and its lower end is buried in the ballast layer (3) to ensure the vertical free movement of the first micro fiber grating static level (8). The second settlement monitoring module includes: a second miniature fiber optic grating hydrostatic level (10).

2. The miniature device and method 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 105mm, width 105mm, and height 42mm.

3. The miniature device and method 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 distance between the fixed bracket (6) and the outer extension of the sleeper (2) can accommodate the slight lateral displacement of the sleeper (2).

4. The miniature device and method 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 and method 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 is located at the reference point and together with the second settlement monitoring module at an independent platform near the railway track. The water tank (11) and each of the first micro fiber grating hydrostatic level (8) and the second micro fiber grating hydrostatic level (10) have a liquid level difference that 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 and method 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 through a vent pipe (15), a liquid 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) through 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 and method for automatically monitoring long-term settlement of railway tracks according to claim 6, characterized in that, The device further includes: Insulating cotton is used to wrap the water tank (11), the first miniature fiber optic grating static level (8) placed on the edge of the sleeper, and the second miniature fiber optic grating static level (10) placed 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); Weld the first miniature fiber optic static level (8) firmly to the fixed base (7), align the third positioning hole (20) on the fixed base (7) with the second positioning hole preset on the short side of the fixed bracket (6), and drive in expansion bolts to fix it; Place the fixed bracket (6), the built-in first micro fiber optic static level (8), and the fixed base (7) together in the protective sleeve (9), align 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 difference between the elevation of the two and the elevation of 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 a water tank (11), and the communication optical cable (17) is connected to a 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 compensation wavelength. Acquire the wavelength data corresponding to the installation of the first miniature fiber optic grating hydrostatic level (8) and / or the second miniature fiber optic grating hydrostatic 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: D=K λ *[(λ-λ0)-K T *(λ T -λ T0 )] Where, K λ K is the proportionality coefficient between the liquid level and the change in wavelength. T λ is the temperature compensation coefficient for the wavelength change; λ is the measured value of the liquid level wavelength, λ0 is the initial measured value of the liquid level wavelength, and λ T For temperature-compensated wavelength measurements, λ T0 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 the liquid level of the first micro fiber grating static level (8) to drop and the water volume to increase, which in turn causes the water volume of the second micro fiber grating static level (10) at the benchmark point to decrease. Therefore, in order to obtain the relative settlement of 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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