Long-distance monitoring method and device for longitudinal differential settlement of tunnel

Abstract

The invention relates to the technical field of tunnel deformation monitoring. More specifically, the invention relates to a long-distance monitoring method and device for longitudinal differential settlement of a tunnel. According to the invention, the array type fiber grating sensor technology is applied to the automatic monitoring of the differential settlement of the large-diameter shield tunnel, and the position and laying angle of the array type fiber grating are fixed based on the advantages of high precision, long distance and strong anti-interference capability of the column type fiber grating technology. Automatic monitoring of differential settlement of a lower structure can be realized by utilizing an array type fiber grating technology so as to reflect differential settlement between different duct pieces of a shield tunnel, potential safety hazards are found and early warned in time, and technical support and decision basis are provided for normal use and maintenance of the tunnel.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel deformation monitoring, and more specifically, to a method and device for long-distance monitoring of longitudinal uneven settlement of a tunnel. Background Art

[0002] As an important structural type that passes under cities, water bodies and buildings, the safety and stability of large-diameter shield tunnels during operation are directly related to the normal operation and use of corresponding transportation facilities. However, due to the weak integrity of the shield tunnel structure, the strata around the large-diameter shield tunnel are easily disturbed under the influence of complex factors such as vehicle vibration and external construction activities, especially in the uneven soft and hard strata, which are more likely to induce uneven settlement. This uneven settlement will not only cause local stress concentration in the structure and increase the risk of structural damage, but also have an adverse effect on the smoothness and safety of the closely connected lower structure (as a key element for bearing vehicle loads). The lower part of a large-diameter shield tunnel is generally a prefabricated box culvert assembly structure, and the upper part is a vehicle passage space. Since the stability of the lower structure is directly related to the driving safety of the upper part, it is particularly urgent and important to carry out real-time and accurate monitoring and analysis of the uneven settlement of large-diameter shield tunnels. To this end, it is proposed to deploy monitoring elements on the side walls of the shield tunnel substructure to monitor and analyze the deformation data, so as to timely grasp the deformation of the shield tunnel and provide technical support for the safe operation of the tunnel.

[0003] However, the current monitoring methods for uneven settlement of shield tunnels still face many limitations. Traditional methods mainly rely on manual monitoring, but they are inefficient and have long feedback cycles. Although some tunnels have tried to introduce automated monitoring technologies, such as automatic total stations, static levels, and traditional fiber grating sensor monitoring, these technologies are not yet perfect: the automatic total station needs to be deployed every 200 meters or so, which is costly and limited by light conditions; the static level monitoring sensors are mainly point sensors such as resistive, steel string, and inductive sensors. This type of sensor generally has the disadvantages of difficult deployment, poor anti-interference ability, poor corrosion resistance, easy damage, and easy data distortion, as well as a small range and high cost; traditional fiber grating sensors have high reflectivity for light signals, but their accuracy is attenuated in long-distance monitoring, and there are fewer measuring points (generally less than 30). It can be seen that the existing automated monitoring technology is not suitable for long-distance use. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems, apply array fiber grating sensor technology to the automatic monitoring of uneven settlement of large-diameter shield tunnels, and provide a long-distance monitoring method and device for longitudinal uneven settlement of tunnels.

[0005] In order to achieve these purposes and other advantages according to the present invention, a method for long-distance monitoring of longitudinal uneven settlement of a tunnel is provided, comprising the following steps:

[0006] S1. N vertical monitoring lines are arranged on the side wall of the tunnel substructure along the longitudinal direction of the tunnel, N ≥ 3, and upper connection points and lower connection points are arranged on the monitoring lines, and a monitoring section is formed between two adjacent monitoring lines;

[0007] S2, two fiber Bragg grating sensors are arranged along the longitudinal direction of the tunnel, and the two fiber Bragg grating sensors are sequentially connected to the upper connection points or the lower connection points on the plurality of monitoring lines, so that the two fiber Bragg grating sensors are distributed in a triangular wave shape with opposite phases;

[0008] S3. Obtain the optical fiber strain of the fiber grating sensor located in each monitoring section respectively, and calculate the vertical displacement direction and size of the i-th monitoring line relative to the i-1-th monitoring line in combination with the longitudinal distance between two adjacent monitoring lines, 2≤i≤N.

[0009] Furthermore, in the long-distance monitoring method for uneven longitudinal settlement of a tunnel, the monitoring line is located on the annular seam of the tunnel substructure.

[0010] Furthermore, in the long-distance monitoring method for uneven longitudinal settlement of a tunnel, the two fiber grating sensors in S2 are staggeredly arranged transversely along the tunnel.

[0011] Furthermore, in the long-distance monitoring method for uneven longitudinal settlement of a tunnel, when the fiber grating sensor in S2 is sequentially connected to upper connection points or lower connection points on a plurality of monitoring lines, the fiber grating sensor is in a stretched state.

[0012] Furthermore, in the long-distance monitoring method for uneven longitudinal settlement of a tunnel, when the fiber grating sensor in S2 is sequentially connected to upper connection points or lower connection points on multiple monitoring lines, the tensile strain of the fiber grating sensor is 2800-3200 με.

[0013] Further, in the long-distance monitoring method for longitudinal uneven settlement of a tunnel, S3 specifically includes:

[0014] S3.1. Obtaining the angle α between the fiber Bragg grating sensor and the horizontal line between the connection point of the i-th monitoring line and the lower connection point of the i-1-th monitoring line, and the angle β between the fiber Bragg grating sensor and the horizontal line between the connection point of the i-th monitoring line and the lower connection point of the i-1-th monitoring line in the initial state;

[0015] S3.2, obtaining the optical fiber strain ε1 of the optical fiber Bragg grating sensor between the connection point of the i-th monitoring line and the lower connection point of the i-1-th monitoring line, and the optical fiber strain ε2 of the optical fiber Bragg grating sensor between the connection point of the i-th monitoring line and the lower connection point of the i-1-th monitoring line under the monitoring state;

[0016] S3.3. When ε1>0, ε2<0, the i-th monitoring line sinks upward relative to the i-1-th monitoring line, and the sinking height Δy is as follows:

[0017]

[0018] Wherein, L is the longitudinal distance between the ith monitoring line and the i-1th monitoring line;

[0019] When ε1<0, ε2>0, the i-th monitoring line sinks downward relative to the i-1-th monitoring line, and the settlement height Δy is as follows:

[0020]

[0021] The present invention also provides a long-distance monitoring device for longitudinal uneven settlement of a tunnel, comprising:

[0022] Multiple fixing devices, N vertical monitoring lines are arranged on the side wall of the tunnel substructure at intervals along the longitudinal direction of the tunnel, N ≥ 3, and upper connection points and lower connection points are arranged on the monitoring lines, and the fixing devices are arranged at the upper connection points and the lower connection points;

[0023] Two fiber grating sensors are sequentially connected to the fixing devices at the upper connection points or the lower connection points on the plurality of monitoring lines, so that the two fiber grating sensors are distributed in a triangular wave shape with opposite phases.

[0024] Furthermore, in the long-distance monitoring device for longitudinal uneven settlement of a tunnel, the fixing device comprises:

[0025] A positioning tube connected to the side wall of the tunnel substructure, wherein the positioning tube is bent in the middle, and the fiber grating sensor passes through the positioning tube;

[0026] A positioning piece, a mounting hole is provided in the middle of the positioning tube, and the positioning piece extends into the mounting hole and is connected to the positioning tube to connect and fix the fiber grating sensor to the positioning tube.

[0027] Furthermore, in the long-distance monitoring device for longitudinal uneven settlement of a tunnel, the positioning tube comprises:

[0028] The bending tube is in an arc shape, a threaded hole is provided in the middle of the bending portion, and the positioning member is a fastening bolt, which extends into the mounting hole and is threadedly connected to the bending tube;

[0029] Two straight tubes are respectively connected to the two ends of the bent tube.

[0030] Furthermore, in the long-distance monitoring device for longitudinal uneven settlement of a tunnel, the fixing device further comprises:

[0031] A fixed steel plate is connected to the side wall of the tunnel substructure, and the positioning tube is arranged on the fixed steel plate.

[0032] The beneficial effects of the present invention are:

[0033] In the long-distance monitoring method for longitudinal uneven settlement of a tunnel of the present invention, based on the advantages of high precision, long distance and strong anti-interference ability of the array fiber grating technology, the position and laying angle of the array fiber grating are fixed, and the array fiber grating technology can be used to realize automatic monitoring of uneven settlement of the lower structure to reflect the differential settlement between different segments of the shield tunnel, timely discover and warn of potential safety hazards, and provide technical support and decision-making basis for the normal use and maintenance of the tunnel.

[0034] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the side wall structure of the tunnel substructure in the monitoring method of the present invention;

[0036] Figure 2 It is a schematic diagram of the settlement conditions of each settlement monitoring point according to the present invention;

[0037] Figure 3 It is a schematic diagram of the structure of the fixing device of the present invention;

[0038] Figure 4 It is a schematic diagram of the structure of the monitoring section described in the present invention.

[0039] Wherein, the reference numerals represent:

[0040] Fiber Bragg grating sensor 1; lower connection point 2; monitoring line 3; fixing steel plate 4; fixing bolt 5; positioning tube 6; positioning piece 7. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0042] It should be noted that, in the description of the present invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc. indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0043] like Figure 1-Figure 4 As shown, an embodiment of the present invention provides a method for long-distance monitoring of longitudinal uneven settlement of a tunnel, comprising the following steps:

[0044] S1. N vertical monitoring lines 3 are arranged on the side wall of the tunnel substructure along the longitudinal direction of the tunnel, N ≥ 3, and an upper connection point and a lower connection point 2 are arranged on the monitoring line 3, and a monitoring section is formed between two adjacent monitoring lines 3; considering the difference in the longitudinal uneven settlement value of the tunnel, the length of the monitoring section can be determined according to the actual situation, and the length of a monitoring section can be taken as 10m-50m;

[0045] S2, two fiber Bragg grating sensors 1 are arranged along the longitudinal direction of the tunnel, and the two fiber Bragg grating sensors 1 are sequentially connected to the upper connection points or the lower connection points 2 on the plurality of monitoring lines 3, so that the two fiber Bragg grating sensors 1 are distributed in a triangular wave shape with opposite phases;

[0046] S3, respectively obtain the optical fiber strain of the fiber grating sensor 1 located in each monitoring section, and combine the longitudinal distance between two adjacent monitoring lines 3 to calculate the settlement direction and height of the i-th monitoring line 3 relative to the i-1-th monitoring line 3, 2≤i≤N. S3 specifically includes:

[0047] S3.1. Obtaining the angle α between the fiber Bragg grating sensor 1 and the horizontal line between the upper connection point of the i-th monitoring line 3 and the lower connection point 2 of the i-1-th monitoring line 3, and the angle β between the fiber Bragg grating sensor 1 and the horizontal line between the lower connection point 2 of the i-th monitoring line 3 and the upper connection point of the i-1-th monitoring line 3 in the initial state;

[0048] S3.2, obtaining the optical fiber strain ε1 of the optical fiber Bragg grating sensor 1 between the upper connection point of the i-th monitoring line 3 and the lower connection point 2 of the i-1-th monitoring line 3, and the optical fiber strain ε2 of the optical fiber Bragg grating sensor 1 between the lower connection point 2 of the i-th monitoring line 3 and the upper connection point of the i-1-th monitoring line 3 under the monitoring state;

[0049] like Figure 3 As shown, in the initial state, the length L0 of the fiber grating sensor 1 between the upper connection point of the i-th monitoring line 3 and the lower connection point 2 of the i-1-th monitoring line 3 is:

[0050]

[0051] After settlement, the length L1 of the fiber Bragg grating sensor 1 between the upper connection point of the i-th monitoring line 3 and the lower connection point 2 of the i-1-th monitoring line 3 is:

[0052]

[0053] Among them, Δy is the vertical displacement of the connection point on the i-th monitoring line 3;

[0054] Based on the above equations (3) and (4), the fiber strain ε1 of the fiber Bragg grating sensor 1 between the upper connection point of the i-th monitoring line 3 and the lower connection point 2 of the i-1-th monitoring line 3 is calculated:

[0055]

[0056] Similarly, the fiber strain ε2 of the fiber Bragg grating sensor 1 between the lower connection point 2 of the i-th monitoring line 3 and the upper connection point of the i-1-th monitoring line 3 is calculated:

[0057]

[0058] S3.3, when ε1>0, ε2<0, the i-th monitoring line 3 sinks upward relative to the i-1-th monitoring line 3, and the sinking height Δy is as follows:

[0059]

[0060] Wherein, L is the longitudinal distance between the ith monitoring line 3 and the i-1th monitoring line 3;

[0061] When ε1<0, ε2>0, the i-th monitoring line 3 sinks downward relative to the i-1-th monitoring line 3, and the sinking height Δy is as follows:

[0062]

[0063] In this embodiment, the arrayed fiber grating technology shows outstanding advantages in the long-distance automated monitoring of large-diameter shield tunnels. The arrayed fiber grating technology has the following advantages: large capacity, the number of sensors on a single optical fiber is ≥10,000; high density, the sensor spacing is ≤10cm; long distance, the sensing distance is ≥10km. The emergence of this technology provides conditions for the automated monitoring of uneven settlement of large-diameter shield tunnels, and has good market potential and application prospects. In this embodiment, a plurality of monitoring lines 3 are set along the longitudinal direction of the tunnel substructure, and each monitoring line 3 serves as a settlement monitoring point, such as Figure 1As shown, two fiber grating sensors 1 are connected to the upper connection points or lower connection points 2 on multiple monitoring lines 3 in sequence, and the two fiber grating sensors 1 are distributed in anti-phase triangular waves, and the fiber grating sensors 1 are in a taut state. The fiber grating sensor 1 is divided into multiple independent monitoring units, and the two ends of the monitoring unit are respectively connected to two adjacent settlement monitoring points. As the tunnel is opened to traffic, the shield tunnel will settle, and each settlement monitoring point will move downward. If the settlement is uniform, the adjacent settlement monitoring points will settle synchronously, and at this time, each settlement monitoring point will not be displaced in the vertical direction relative to the previous settlement monitoring point. When the shield tunnel has uneven settlement, the direction and size of the displacement of each settlement monitoring point relative to the previous settlement monitoring point may be different. Therefore, in this embodiment, the settlement direction and height of the i-th monitoring line 3 relative to the i-1-th monitoring line 3 are calculated in sequence, that is, only the vertical displacement direction and size of each settlement monitoring point relative to the previous settlement monitoring point are calculated, and the settlement monitoring point where the first monitoring line 3 is located is taken as the reference point, and the positions of the settlement monitoring points where other monitoring lines 3 are located can be calculated in sequence, such as Figure 2 As shown, by drawing a line graph of the settlement of each settlement monitoring point, the automatic monitoring of uneven settlement of the lower structure can be realized, and potential safety hazards can be discovered and warned in time, providing technical support and decision-making basis for the normal use and maintenance of the tunnel. Preferably, as another embodiment of the present invention, the monitoring line 3 is located on the annular seam of the tunnel lower structure.

[0064] In this embodiment, based on the fact that the shield tunnel is composed of multiple segments, the monitoring line 3 is located on the annular joint of the tunnel substructure, that is, two adjacent monitoring lines 3 are respectively located on the annular joints on both sides of the same segment, that is, a single segment is used as a monitoring section, which can reflect the differential settlement between different segments of the shield tunnel.

[0065] Preferably, as another embodiment of the present invention, the two fiber grating sensors 1 in S2 are staggeredly arranged transversely along the tunnel.

[0066] In this embodiment, when fixing two fiber grating sensors 1, the two fiber grating sensors 1 are staggered along the tunnel horizontally to prevent the two fiber grating sensors 1 from contacting each other and bending in the vertical plane, thereby affecting the accuracy of the fiber strain measurement of the fiber grating sensor 1.

[0067] Preferably, as another embodiment of the present invention, when the fiber grating sensor 1 in S2 is sequentially connected to the upper connection points or the lower connection points 2 on the plurality of monitoring lines 3, the fiber grating sensor 1 is in a stretched state.

[0068] In this embodiment, the fiber Bragg grating sensor 1 is in a stretched state, which prevents the fiber Bragg grating sensor 1 from being in a relaxed state, and ensures that when two settlement monitoring points in the monitoring section move relative to each other, the fiber strain measurement of the fiber Bragg grating sensor 1 is more accurate. When the fiber Bragg grating sensor 1 in S2 is sequentially connected to the upper connection point or the lower connection point 2 on the plurality of monitoring lines 3, the tensile strain of the fiber Bragg grating sensor 1 is 2800-3200 με.

[0069] The present invention also provides a long-distance monitoring device for longitudinal uneven settlement of a tunnel, comprising:

[0070] Multiple fixing devices, N vertical monitoring lines are arranged on the side wall of the tunnel substructure at intervals along the longitudinal direction of the tunnel, N ≥ 3, and upper connection points and lower connection points are arranged on the monitoring lines, and the fixing devices are arranged at the upper connection points and the lower connection points;

[0071] Two fiber grating sensors are sequentially connected to the fixing devices at the upper connection points or the lower connection points on the plurality of monitoring lines, so that the two fiber grating sensors are distributed in a triangular wave shape with opposite phases.

[0072] In this embodiment, two fixing devices are arranged on each monitoring line 3, and two fiber grating sensors 1 are sequentially connected to the fixing devices at the upper connection points or the lower connection points 2 on the plurality of monitoring lines 3, so that the two fiber grating sensors 1 are distributed in a triangular wave shape with opposite phases. When the monitoring device is used, the fiber strain of the fiber grating sensor 1 located in each monitoring section is obtained respectively, and the settlement direction and height of the i-th monitoring line 3 relative to the i-1-th monitoring line 3 are calculated in sequence in combination with the longitudinal distance between two adjacent monitoring lines 3, 2≤i≤N.

[0073] Preferably, as another embodiment of the present invention, Figure 3 As shown, the fixing device comprises:

[0074] A positioning tube 6 connected to the side wall of the tunnel substructure, wherein the positioning tube 6 is bent in the middle, and the fiber grating sensor 1 passes through the positioning tube 6;

[0075] A positioning member 7 is provided with a mounting hole in the middle of the positioning tube 6 , and the positioning member 7 extends into the mounting hole and is connected to the positioning tube 6 , so as to connect and fix the fiber grating sensor 1 to the positioning tube 6 .

[0076] In this embodiment, the fiber grating sensor 1 passes through the positioning tube 6, the fiber grating sensor 1 is limited by the positioning tube 6, and then the positioning member 7 is extended into the installation hole and connected to the positioning tube 6, and the fiber grating sensor 1 is fixed in the positioning tube 6 by the positioning member 7, thereby realizing the connection between the fiber grating sensor 1 and the fixing device.

[0077] Preferably, as another embodiment of the present invention, the positioning tube 6 comprises:

[0078] The bending tube is in an arc shape, a threaded hole is provided in the middle of the bending portion, and the positioning member 7 is a fastening bolt, which extends into the mounting hole and is threadedly connected to the bending tube;

[0079] Two straight tubes are respectively connected to the two ends of the bent tube.

[0080] In this embodiment, the fiber Bragg grating sensor 1 needs to be bent after passing through the positioning tube 6. The arc-shaped bending tube prevents the fiber Bragg grating sensor 1 from being damaged due to excessive bending. Tighten the fastening bolts, clamp the fiber Bragg grating sensor 1 through the fastening bolts and the bending tube, and fix the fiber Bragg grating sensor 1.

[0081] Preferably, as another embodiment of the present invention, the fixing device further comprises:

[0082] The fixed steel plate 4 is connected to the side wall of the tunnel substructure, and the positioning tube 6 is arranged on the fixed steel plate 4 .

[0083] In this embodiment, the fixing steel plate 4 is fixed to the side wall of the tunnel substructure by a plurality of fixing bolts 5 , and the positioning tube 6 is welded to the fixing steel plate 4 .

[0084] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A long-distance monitoring method for longitudinal uneven settlement of a tunnel, characterized in that: The following steps are involved: S1. N vertical monitoring lines are arranged on the side wall of the tunnel substructure along the longitudinal direction of the tunnel, N ≥ 3, and upper connection points and lower connection points are arranged on the monitoring lines, and a monitoring section is formed between two adjacent monitoring lines; S2, two fiber Bragg grating sensors are arranged along the longitudinal direction of the tunnel, and the two fiber Bragg grating sensors are sequentially connected to the upper connection points or the lower connection points on the plurality of monitoring lines, so that the two fiber Bragg grating sensors are distributed in a triangular wave shape with opposite phases; S3. Obtain the optical fiber strain of the fiber grating sensor located in each monitoring section respectively, and calculate the vertical displacement direction and size of the i-th monitoring line relative to the i-1-th monitoring line in combination with the longitudinal distance between two adjacent monitoring lines, 2≤i≤N.

2. The long-distance monitoring method for longitudinal uneven settlement of a tunnel according to claim 1, characterized in that: The monitoring line is located on the annular seam of the tunnel substructure.

3. The long-distance monitoring method for longitudinal uneven settlement of a tunnel according to claim 1, characterized in that: The two fiber grating sensors in S2 are arranged in an alternating manner along the tunnel transversely.

4. The long-distance monitoring method for longitudinal uneven settlement of a tunnel according to claim 1, characterized in that: When the fiber Bragg grating sensor in S2 is connected to the upper connection points or the lower connection points on the plurality of monitoring lines in sequence, the fiber Bragg grating sensor is in a stretched state.

5. The long-distance monitoring method for longitudinal uneven settlement of a tunnel according to claim 4, characterized in that: When the fiber grating sensor in S2 is connected to the upper connection points or the lower connection points on a plurality of monitoring lines in sequence, the tensile strain on the fiber grating sensor is 2800-3200 με.

6. The long-distance monitoring method for longitudinal uneven settlement of a tunnel according to claim 1, characterized in that: S3 specifically includes: S3.

1. Obtaining the angle α between the fiber Bragg grating sensor and the horizontal line between the connection point of the i-th monitoring line and the lower connection point of the i-1-th monitoring line, and the angle β between the fiber Bragg grating sensor and the horizontal line between the connection point of the i-th monitoring line and the lower connection point of the i-1-th monitoring line in the initial state; S3.2, obtaining the optical fiber strain ε1 of the optical fiber Bragg grating sensor between the connection point of the i-th monitoring line and the lower connection point of the i-1-th monitoring line, and the optical fiber strain ε2 of the optical fiber Bragg grating sensor between the connection point of the i-th monitoring line and the lower connection point of the i-1-th monitoring line under the monitoring state; S3.

3. When ε1>0, ε2<0, the i-th monitoring line sinks upward relative to the i-1-th monitoring line, and the sinking height Δy is as follows: Wherein, L is the longitudinal distance between the ith monitoring line and the i-1th monitoring line; When ε1<0, ε2>0, the i-th monitoring line sinks downward relative to the i-1-th monitoring line, and the settlement height Δy is as follows:

7. A long-distance monitoring device for longitudinal uneven settlement of a tunnel, comprising: Multiple fixing devices, N vertical monitoring lines are arranged on the side wall of the tunnel substructure at intervals along the longitudinal direction of the tunnel, N ≥ 3, and upper connection points and lower connection points are arranged on the monitoring lines, and the fixing devices are arranged at the upper connection points and the lower connection points; Two fiber grating sensors are sequentially connected to the fixing devices at the upper connection points or the lower connection points on the plurality of monitoring lines, so that the two fiber grating sensors are distributed in a triangular wave shape with opposite phases.

8. The long-distance monitoring device for longitudinal uneven settlement of a tunnel according to claim 7, characterized in that: The fixing device comprises: A positioning tube connected to the side wall of the tunnel substructure, wherein the positioning tube is bent in the middle, and the fiber grating sensor passes through the positioning tube; A positioning piece, a mounting hole is provided in the middle of the positioning tube, and the positioning piece extends into the mounting hole and is connected to the positioning tube to connect and fix the fiber grating sensor to the positioning tube.

9. The long-distance monitoring device for longitudinal uneven settlement of a tunnel according to claim 8, characterized in that: The positioning tube comprises: The bending tube is in an arc shape, a threaded hole is provided in the middle of the bending portion, and the positioning member is a fastening bolt, which extends into the mounting hole and is threadedly connected to the bending tube; Two straight tubes are respectively connected to the two ends of the bent tube.

10. The long-distance monitoring device for longitudinal uneven settlement of a tunnel according to claim 8, characterized in that: The fixing device also includes: A fixed steel plate is connected to the side wall of the tunnel substructure, and the positioning tube is arranged on the fixed steel plate.

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