Fiber bragg grating roof separation monitoring device and method

Abstract

The invention belongs to the technical field of roadway surrounding rock monitoring, and particularly relates to a fiber bragg grating roof separation monitoring device and method.The device comprises an anchor fluke, a shell, a rope, a sleeve, a protection box and a fiber bragg grating and further comprises a movement detection mechanism; the mobile detection mechanism comprises a winding drum, a lead screw, a base, a first magnet, a concave block, a sliding block, a fixing plate, an elastic frame, rotating teeth and a compression spring. The fiber bragg grating roof separation monitoring device solves the problem that in the monitoring process of an existing fiber bragg grating monitoring device, due to fatigue stress, loosening and falling of bonding points and damage of sensitive elements, the monitoring precision is reduced, redundant configuration of signals during monitoring is achieved, and the precision and reliability of the fiber bragg grating roof separation monitoring device are greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel surrounding rock monitoring, and in particular relates to a fiber grating roof separation monitoring device and method. Background Art

[0002] In the modern coal mining process, the stability of the roof is one of the key factors to ensure the safe production of the mine. The monitoring of roof delamination is of great significance for early warning of tunnel collapse and ensuring the safety of miners. Nowadays, the more common monitoring method at home and abroad is to install a roof delamination meter based on the electrical measurement method, but in actual application, it faces problems such as poor durability, weak anti-interference ability, and limited signal transmission distance. Especially in the high temperature and high humidity environment underground in coal mines, it will accelerate the aging of the device and easily cause sensor failure.

[0003] In recent years, the research and application of fiber Bragg grating sensing technology has attracted widespread attention. Compared with traditional sensing and measurement technologies, fiber Bragg grating sensing has many obvious advantages, such as strong resistance to moisture, corrosion, and interference, and easy to form a sensing network. At present, fiber Bragg grating sensing technology has been applied to the measurement of state quantities such as anchor stress and surrounding rock displacement in coal mines. However, during the long-term service of the sensitive elements of the fiber Bragg grating sensing device, due to the effect of fatigue stress, it is easy to cause the bonding points to loosen and fall off, and the sensitive elements to be damaged, thereby reducing the reliability of the measurement.

[0004] Therefore, the present invention provides a fiber grating top plate delamination monitoring device and method. Summary of the invention

[0005] The purpose of the present invention is to solve the problem that during the monitoring process of the existing fiber grating monitoring device, the loosening and falling of the bonding points and the damage of the sensitive elements due to fatigue stress, which leads to the reduction of monitoring accuracy, realize the redundant configuration of the signal during monitoring, and greatly improve the accuracy and reliability of the fiber grating top plate delamination monitoring device.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A fiber Bragg grating top plate separation monitoring device comprises an anchor claw, a shell, a rope, a sleeve, a protection box and a fiber Bragg grating; the shell is connected to the anchor claw through a rope; a sleeve is provided on the top of the shell, and the sleeve is sleeved on the outside of the rope; the protection box is provided on both sides of the shell, and the fiber Bragg grating passes through the protection box and the inside of the shell in sequence; It also includes: a movement detection mechanism, the movement detection mechanism is located in the housing and the protection box; The mobile detection mechanism comprises: a reel, a lead screw, a coil spring, a base, a No. 1 magnet, a concave block, a slider, a fixing plate, an elastic frame, a rotating tooth and a compression spring; A screw rod is provided in the drum, a coil spring is provided on the outer side of the drum, the drum is located inside the shell, the drum is connected to the rope, the base is provided inside the protective box, a concave block, a slider and an elastic frame are arranged on the base in sequence, a compression spring is provided between the slider and the elastic frame, a No. 1 magnet is provided on the top of the concave block, a fixing plate is provided on the top of the slider, a T-shaped elastic plate extending outward is provided on the side of the fixing plate close to the concave block, and the T-shaped elastic plate is located above the No. 1 magnet; the screw rod passes through the concave block, the slider, the compression spring and the elastic frame in sequence, and a rotating tooth is provided at the end of the screw rod.

[0007] Preferably, the elastic frame comprises: a rectangular bottom plate, a column, a pressure plate, a push plate, a vertical plate, a horizontal plate and a rib plate; The rectangular bottom plate is arranged on the base, and a gap is left between the two upright posts and the rectangular bottom plate; the upright plate and the rectangular bottom plate form an L-shaped structure; a rib plate is arranged between the upright plate and the rectangular bottom plate; a horizontal plate is arranged at the top of the upright plate; Two columns are provided on the rectangular bottom plate, the pressure plate is arranged horizontally and located on the two columns, the push plate is placed vertically, forming an inverted L-shaped structure with the pressure plate, and the push plate is located between the two columns and the rectangular bottom plate; a circular through hole is opened in the middle of the push plate, and a gap is left between the pressure plate and the cross plate.

[0008] Preferably, a second magnet is provided at the bottom of the horizontal plate outside the vertical plate, and the second magnet is located directly above the rotating tooth, and the rotating tooth is made of magnetic material, and the magnetic poles between two adjacent teeth are different.

[0009] Preferably, two gaskets are provided on the top of the horizontal plate outside the vertical plate, and the two gaskets are symmetrically located on both sides of the fiber grating.

[0010] Preferably, a plurality of grids are symmetrically arranged on both sides of the fiber Bragg grating, and the plurality of grids are respectively located on the T-shaped elastic plate, the fixing plate, the pressure plate and the cross plate.

[0011] Preferably, the pressure plate and the push plate are integrally formed, and the column is made of elastic material.

[0012] Preferably, the fiber grating is connected to the T-shaped elastic plate, the pressure plate and the cross plate respectively through a polymer adhesive.

[0013] A delamination monitoring method for a fiber grating top plate delamination monitoring device comprises the following steps: S1: Conduct a calibration experiment in the laboratory to calculate the conversion coefficient between the displacement of the surrounding rock layer and the central wavelength offset of the fiber grating of the monitoring device after temperature compensation, and calculate the linear regression errors of the three observation points respectively; S2: Drill holes on site in the tunnel, install the separation monitoring device, fix two anchor claws in the deep and shallow rock formations respectively, insert the casing into the borehole and fix it with steel claws, and connect the fiber Bragg grating to the demodulator; S3: As the surrounding rock moves inside, the anchor claw drives the lead screw to rotate by pulling the rope, driving the slider to move on the base; the movement of the slider drives the T-shaped elastic plate to move on the top of the No. 1 magnet, and the magnetic force between the T-shaped elastic plate and the No. 1 magnet changes. As the T-shaped elastic plate moves away from the No. 1 magnet, the magnetic force decreases, and the fiber Bragg grating deforms along with the T-shaped elastic plate; When the slider moves, it pushes the compression spring, which is compressed and pushes the push plate to move. When the push plate moves on the column, it drives the side of the pressure plate close to the horizontal plate to move upward, so that the pressure plate drives the fiber grating to deform. When the lead screw rotates, it drives the rotating teeth to rotate, and the magnetic force between the rotating teeth and the second magnet changes, causing the horizontal plate on the vertical plate to move up and down, and driving the fiber grating to deform; S4: Measure the changes of the fiber Bragg grating center wavelength offset at three points simultaneously, and convert the values ​​of each fiber Bragg grating measurement point into surrounding rock displacement according to the conversion coefficient calculated in step S1. Let the data sets of the three measurement points on one side be x i ,y i , z i , the following correlation coefficient is used to calculate the correlation between the data of the three measuring points on one side of the device after temperature compensation: , , ; S5: Analyze the correlation results. If r xy , r yz , r xz If all three are greater than 0.8 and less than or equal to 1, the final measurement output is the displacement value calculated by the fiber Bragg grating with the smallest linear regression error in step S1; if r xy , r yz , r xz If only one value is greater than 0.8 and less than or equal to 1, and the output results of the two grids represented by this value change dynamically, the displacement value calculated by the fiber Bragg grating with the smaller linear regression error in the two grids represented by this value is selected as the output to determine that the other fiber Bragg grating is faulty; if r xy , r yz , r xz If all three are less than 0.8, it is judged as a structural failure or a fiber Bragg grating failure and repair is required.

[0014] Beneficial effects of the present invention: 1. The present invention detects rock formations by pulling mobile detection mechanisms through ropes to cooperate with each other, and detects fiber Bragg gratings at multiple points simultaneously through the mobile detection mechanism, thereby ensuring signal redundancy in the dynamic monitoring process. When the surrounding rock deformation drives the internal structure of the device to displace, the wavelength of the fiber Bragg grating transmission is driven to change. Through temperature compensation and correlation analysis, the effective positioning of the fault signal is achieved, and effective measurement results can be output, thereby greatly improving the accuracy and reliability of the fiber Bragg grating top plate separation monitoring device.

[0015] 2. The present invention provides a fixing plate and a No. 1 magnet on the screw rod, changes the distance between the fixing plate and the No. 1 magnet, thereby changing the magnetic force between the two, and causing the fixing plate and the fiber optic Bragg grating bonded to the top to deform, thereby changing the wavelength of the fiber optic Bragg grating transmission and improving the accuracy of top plate delamination monitoring.

[0016] 3. The present invention makes the slider on the screw rod slide and push the push plate on the elastic frame, so that the push plate drives the pressure plate to move and drives the fiber optic Bragg grating to deform, changing the wavelength of the fiber optic Bragg grating transmission, thereby improving the accuracy of top plate delamination monitoring.

[0017] 4. The present invention drives the rotating teeth on the end of the screw rod to rotate through the rotation of the screw rod, and changes the distance between the rotating teeth and the second magnet, so that the horizontal plate outside the vertical plate vibrates, and drives the fiber optic Bragg grating to deform, changing the wavelength of the fiber optic Bragg grating transmission, thereby improving the accuracy of top plate delamination monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is an exploded view of the present invention as a whole.

[0019] Figure 2 For the present invention Figure 1 Enlarged view of point A in the middle.

[0020] Figure 3 For the present invention Figure 2 Enlarged view of point B in the middle.

[0021] Figure 4 It is a schematic diagram of the three-dimensional structure of the elastic frame of the present invention.

[0022] Figure 5 It is a schematic diagram of the three-dimensional structure inside the reel of the present invention.

[0023] In the figure: 1. anchor claw; 2. shell; 3. rope; 4. sleeve; 5. protection box; 6. fiber grating; 7. mobile detection mechanism; 71. reel; 72. screw rod; 721. rotating tooth; 73. coil spring; 74. base; 75. No. 1 magnet; 751. concave block; 76. slider; 77. fixed plate; 771. T-shaped elastic plate; 78. elastic frame; 781. No. 2 magnet; 782. rectangular bottom plate; 783. column; 784. pressure plate; 785. push plate; 786. circular through hole; 787. vertical plate; 788. horizontal plate; 789. rib plate; 79. compression spring; 8. gasket. DETAILED DESCRIPTION

[0024] The method for using the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0025] like Figures 1 to 5 As shown, a fiber Bragg grating top plate separation monitoring device comprises an anchor claw 1, a shell 2, a rope 3, a sleeve 4, a protection box 5 and a fiber Bragg grating 6; the shell 2 is connected to the anchor claw 1 through the rope 3; a sleeve 4 is provided on the top of the shell 2, and the sleeve 4 is sleeved on the outside of the rope 3; the protection box 5 is provided on both sides of the shell 2, and the fiber Bragg grating 6 passes through the protection box 5 and the inside of the shell 2 in sequence; It also includes: a mobile detection mechanism 7, which is located in the housing 2 and the protection box 5; the mobile detection mechanism 7 is moved by pulling the rope 3, and squeezes the fiber grating 6 to deform, thereby changing the wavelength transmitted by the fiber grating 6.

[0026] like Figures 2 to 5 As shown, the mobile detection mechanism 7 includes: a reel 71, a screw rod 72, a coil spring 73, a base 74, a first magnet 75, a concave block 751, a slider 76, a fixed plate 77, an elastic frame 78, a rotating tooth 721 and a compression spring 79; The reel 71 is provided with a screw rod 72 inside, and a coil spring 73 is provided on the outside of the reel 71. The reel 71 fixes one end of the screw rod 72, and the outside of the reel 71 is used to install the coil spring 73. When resetting, the coil spring 73 rotates to drive the reel 71 to rotate inside the housing 2, thereby driving the screw rod 72 to rotate and reset; the reel 71 is located inside the housing 2, the reel 71 is connected to the rope 3, the base 74 is arranged inside the protection box 5, and the base 74 is sequentially arranged with a concave block 751, a slider 76 and an elastic frame 78, and a compression is arranged between the slider 76 and the elastic frame 78. Spring 79, compression spring 79 can be used to drive the slider 76 to reset, a No. 1 magnet 75 is provided on the top of the concave block 751, a fixing plate 77 is provided on the top of the slider 76, the fixing plate 77 can be connected to the top of the slider 76 by bolts, a T-shaped elastic plate 771 extending outward is provided on the side of the fixing plate 77 close to the concave block 751, and the T-shaped elastic plate 771 is located above the No. 1 magnet 75; the screw rod 72 passes through the concave block 751, the slider 76, the compression spring 79 and the elastic frame 78 in sequence, and a rotating tooth 721 is provided at the end of the screw rod 72.

[0027] It should be noted that the distance between the top of magnet No. 1 75 and the bottom of T-shaped elastic plate 771 is between 2mm and 5mm. As the slider 76 drives the T-shaped elastic plate 771 to move, the magnetic force between the T-shaped elastic plate 771 and magnet No. 1 75 will change, so that the T-shaped elastic plate 771 drives the fiber grating 6 to deform.

[0028] It should be noted that the T-shaped elastic plate 771 is initially in an upwardly bent state, and the optical fiber Bragg grating 6 is pasted above the T-shaped elastic plate 771. When the T-shaped elastic plate 771 is located directly above the No. 1 magnet 75, the T-shaped elastic plate 771 will be deformed from the bent state to the horizontal state due to the magnetic adsorption force. At this time, the optical fiber Bragg grating 6 above the T-shaped elastic plate 771 will not change. When the slider drives the T-shaped elastic plate 771 to move toward the elastic frame 78, the distance between the T-shaped elastic plate 771 and the No. 1 magnet 75 will increase, and the magnetic force will weaken, so that the T-shaped elastic plate 771 will drive the optical fiber Bragg grating 6 to deform.

[0029] like Figure 4 As shown, the elastic frame 78 includes: a rectangular bottom plate 782, a column 783, a pressure plate 784, a push plate 785, a vertical plate 787, a horizontal plate 788 and a rib plate 789; the rectangular bottom plate 782 is arranged on the base 74, and a gap is left between the two vertical columns 783 and the rectangular bottom plate 782; the vertical plate 787 and the rectangular bottom plate 782 form an L-shaped structure; a rib plate 789 is arranged between the vertical plate 787 and the rectangular bottom plate 782; a horizontal plate 788 is arranged at the top of the vertical plate 787; Two columns 783 are provided on the rectangular bottom plate 782, the pressure plate 784 is arranged horizontally and located on the two columns 783, the push plate 785 is placed vertically, and forms an inverted L-shaped structure with the pressure plate 784, and the push plate 785 is located between the two columns 783 and the rectangular bottom plate 782; a circular through hole 786 is opened in the middle of the push plate 785, and a gap is left between the pressure plate 784 and the cross plate 788.

[0030] There is a gap between the pressure plate 784 and the cross plate 788 to ensure that when the pressure plate 784 is deformed, there will be no interference with the cross plate 788, and there is enough space for the pressure plate 784 to drive the fiber grating 6 to deform.

[0031] like Figure 2 and Figure 3 As shown, a second magnet 781 is provided at the bottom of the horizontal plate 788 outside the vertical plate 787, and the second magnet 781 is located directly above the rotating tooth 721, and the rotating tooth 721 is made of magnetic material, and the magnetic poles between two adjacent teeth are different.

[0032] This is to ensure that during the rotation of the rotating tooth 721, the magnetic force between the rotating tooth 721 and the second magnet 781 can change, so that the horizontal plate 788 moves up and down to drive the fiber grating 6 to deform.

[0033] The distance between the bottom of the second magnet 781 and the upper surface of the gear teeth is between 2mm and 5mm. As the gear rotates, the distance between the two changes, and the magnetic force will also change accordingly, causing the cross plate 788 to move up and down and drive the fiber grating 6 to deform.

[0034] like Figure 2 As shown, two gaskets 8 are provided on the top of the transverse plate 788 outside the vertical plate 787 , and the two gaskets 8 are symmetrically located on both sides of the fiber grating 6 .

[0035] A plurality of grids are symmetrically arranged on both sides of the fiber Bragg grating 6 , and the plurality of grids are respectively located on the T-shaped elastic plate 771 , the fixing plate 77 , the pressure plate 784 and the transverse plate 788 .

[0036] It should be noted that the grid fixed on the grid stem of the fixed plate 77 is not affected by force and is used for temperature compensation. Because temperature can cause wavelength changes, a grid that is not affected by force is needed to compensate for the influence of ambient temperature.

[0037] The pressure plate 784 and the push plate 785 are integrally formed, and the column 783 is made of elastic material. When the push plate 785 is pushed, the push plate 785 drives the pressure plate 784 to move upward, and the connection between the column 783 and the pressure plate 784 is elastically deformed. When the push plate 785 is not subjected to force, it returns to its original position through elastic force.

[0038] The fiber Bragg grating 6 is connected to the T-shaped elastic plate 771, the pressure plate 784 and the cross plate 788 respectively through a polymer adhesive. This is to ensure that the fiber Bragg grating 6 can always be in contact with the T-shaped elastic plate 771, the pressure plate 784 and the cross plate 788, and when deformation occurs, the fiber Bragg grating 6 can be driven to deform together.

[0039] A delamination monitoring method of a fiber Bragg grating 6 top plate delamination monitoring device comprises the following steps: S1: Conduct a calibration experiment in the laboratory to calculate the conversion coefficient between the displacement of the surrounding rock layer and the central wavelength offset of the fiber Bragg grating 6 of the monitoring device after temperature compensation, and calculate the linear regression errors of the three observation points respectively; S2: Drill holes on site in the tunnel, install the separation monitoring device, fix two anchor claws 1 to the deep and shallow rock formations respectively, insert the casing 4 into the borehole and fix it through the steel claws, and connect the fiber Bragg grating 6 to the demodulator; S3: As the surrounding rock moves inside, the anchor claw 1 drives the screw rod 72 to rotate by pulling the rope 3, and drives the slider 76 to move on the base 74; the movement of the slider 76 drives the T-shaped elastic plate 771 to move on the top of the No. 1 magnet 75, and the magnetic force between the T-shaped elastic plate 771 and the No. 1 magnet 75 changes. As the T-shaped elastic plate 771 moves away from the No. 1 magnet 75, the magnetic force decreases, and the fiber Bragg grating 6 is deformed along with the T-shaped elastic plate 771; When the slider 76 moves, it pushes the compression spring 79, which is compressed and pushes the push plate 785 to move. When the push plate 785 moves on the column 783, it drives the pressure plate 784 to move upward on the side close to the horizontal plate 788, so that the pressure plate 784 drives the fiber grating 6 to deform. When the screw rod 72 rotates, the rotating tooth 721 is driven to rotate, and the magnetic force between the rotating tooth 721 and the second magnet 781 changes, so that the horizontal plate 788 on the vertical plate 787 moves up and down, and drives the fiber grating 6 to deform; S4: Measure the changes caused by the central wavelength deviation of the fiber Bragg grating 6 at three points simultaneously, and convert the values ​​of each measuring point of the fiber Bragg grating 6 into the surrounding rock displacement according to the conversion coefficient calculated in step S1. Let the data sets of the three measuring points on one side be x i ,y i , z i , the following correlation coefficient is used to calculate the correlation between the data of the three measuring points on one side of the device after temperature compensation: , , ; S5: Analyze the correlation results. If r xy , r yz , r xz If all three are greater than 0.8 and less than or equal to 1, the final measurement output is the displacement value calculated by the fiber Bragg grating 6 with the smallest linear regression error in step S1; xy , r yz , r xz If only one value is greater than 0.8 and less than or equal to 1, and the output results of the two grids represented by this value change dynamically, the displacement value calculated by the fiber Bragg grating 6 with the smaller linear regression error in the two grids represented by this value is selected as the output, and the other fiber Bragg grating 6 is judged to be faulty; if r xy , r yz , r xz If all three are less than 0.8, it is determined to be a structural failure or a fiber Bragg grating 6 failure and repair is performed.

[0040] Working process: the anchor claw 1 is driven into and fixed inside the rock formation, and connected to the anchor claw 1 through the rope 3 in the casing 4. When the rock formation is loose, the anchor claw 1 is driven to move, and the anchor claw 1 will rotate by pulling the reel 71, and the reel 71 drives the screw rod 72 to rotate. At the same time, the rotation of the reel 71 drives the coil spring 73 to contract, and the rotation of the screw rod 72 will drive the slider 76 to move outward on the base 74, and the T-shaped elastic plate 771 on the side of the fixed plate 77 at the top of the slider 76 close to the first magnet 75 is located directly above the first magnet 75. When the fixed plate 77 is in the process of moving away from the first magnet 75, the magnetic force between the T-shaped elastic plate 771 and the first magnet 75 decreases, and the T-shaped elastic plate 771 will be deformed, and drive the fiber grating 6 on the top of the T-shaped elastic plate 771 to deform along with the T-shaped elastic plate 771; At the same time, when the slider 76 moves, the sliding movement will push the compression spring 79, the compression spring 79 will be compressed, and push the push plate 785 to move, while the bottom end of the push plate 785 moves outward on the column 783, driving the side of the pressure plate 784 close to the horizontal plate 788 to move upward, so that the pressure plate 784 drives the fiber grating 6 to deform; Furthermore, when the screw rod 72 rotates, the rotating teeth 721 at the end of the screw rod 72 will be driven to rotate. Due to the different pitches of the rotating teeth 721, the distance between the rotating teeth 721 and the second magnet 781 will also change, and the magnetic force between the two will change, so that the horizontal plate 788 outside the vertical plate 787 moves up and down, and drives the fiber grating 6 to deform. Through the grids symmetrically arranged on both sides of the fiber Bragg grating 6, a variety of different grids can reflect eight wavelengths of light, namely 1530nm, 1535nm, 1540nm, 1545nm, 1550nm, 1555nm, 1560mm and 1565mm. As the sensing structure undergoes a slight deformation, the central wavelength of the reflected light corresponding to the measuring point will move, that is, the deformation size of the measuring point can be calculated based on the change of the wavelength; the three points simultaneously measure the change of the central wavelength offset of the fiber Bragg grating 6, calculate the conversion coefficient of the surrounding rock delamination displacement and the central wavelength offset of the fiber Bragg grating 6 of the monitoring device after temperature compensation, and convert the numerical values ​​of each measuring point of the fiber Bragg grating 6 into surrounding rock displacement.

[0041] It should be noted that: it is necessary to first conduct a calibration experiment in the laboratory to calculate the conversion coefficient between the displacement of the surrounding rock layer and the central wavelength offset of the fiber Bragg grating 6 of the monitoring device after temperature compensation, and calculate the linear regression errors of the three observation points respectively; When the central wavelength offset of the fiber Bragg grating 6 changes, the values ​​of each measuring point of the fiber Bragg grating 6 are converted into surrounding rock displacement according to the conversion coefficient, and the correlation coefficient is used to calculate the correlation between the data of the three measuring points on one side of the device after temperature compensation; Finally, the correlation results are analyzed. If the three correlation coefficients are all greater than 0.8 and less than or equal to 1, the final measurement output is the displacement value calculated by the fiber Bragg grating 6 with the smallest linear regression error in the calibration experiment; if only one of the three correlation coefficients is greater than 0.8 and less than or equal to 1, and the output results of the two sensors represented by this value change dynamically, the displacement value calculated by the fiber Bragg grating 6 with the smaller linear regression error among the two sensors represented by this value is selected as the output, and it is determined that the other fiber Bragg grating 6 has a fault; if all three correlation coefficients are less than 0.8, it is determined to be a structural fault or a fiber Bragg grating 6 fault, and maintenance is performed.

[0042] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. However, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A fiber Bragg grating top plate separation monitoring device, comprising an anchor claw (1), a shell (2), a rope (3), a sleeve (4), a protection box (5) and a fiber Bragg grating (6); the shell (2) is connected to the anchor claw (1) through the rope (3); a sleeve (4) is provided on the top of the shell (2), and the sleeve (4) is sleeved on the outside of the rope (3); the protection box (5) is provided on both sides of the shell (2), and the fiber Bragg grating (6) passes through the protection box (5) and the inside of the shell (2) in sequence; It is characterized in that It also comprises: a movement detection mechanism (7), the movement detection mechanism (7) being located inside the housing (2) and the protection box (5); The mobile detection mechanism (7) comprises: a reel (71), a screw rod (72), a coil spring (73), a base (74), a No. 1 magnet (75), a concave block (751), a slider (76), a fixed plate (77), an elastic frame (78), a rotating tooth (721) and a compression spring (79); A screw rod (72) is provided inside the reel (71), a coil spring (73) is provided outside the reel (71), the reel (71) is located inside the housing (2), the reel (71) is connected to the rope (3), the base (74) is arranged inside the protection box (5), a concave block (751), a slider (76) and an elastic frame (78) are arranged on the base (74) in sequence, a compression spring (79) is provided between the slider (76) and the elastic frame (78), the concave block (751) is provided with a compression spring (79), and the concave block (751) is provided with a compression spring (79) between the slider (76) and the elastic frame (78). 1) A No. 1 magnet (75) is provided on the top, a fixing plate (77) is provided on the top of the slider (76), a T-shaped elastic plate (771) extending outward is provided on a side of the fixing plate (77) close to the concave block (751), and the T-shaped elastic plate (771) is located above the No. 1 magnet (75); the lead screw (72) passes through the concave block (751), the slider (76), the compression spring (79) and the elastic frame (78) in sequence, and a rotating tooth (721) is provided at the end of the lead screw (72).

2. The fiber grating top plate delamination monitoring device according to claim 1, characterized in that: The elastic frame (78) comprises: a rectangular bottom plate (782), a column (783), a pressure plate (784), a push plate (785), a vertical plate (787), a horizontal plate (788) and a rib plate (789); The rectangular bottom plate (782) is arranged on the base (74), and a gap is left between the two upright posts (783) and the rectangular bottom plate (782); the upright plate (787) and the rectangular bottom plate (782) form an L-shaped structure; a rib plate (789) is arranged between the upright plate (787) and the rectangular bottom plate (782); and a horizontal plate (788) is provided at the top end of the upright plate (787); Two columns (783) are provided on the rectangular bottom plate (782); the pressure plate (784) is arranged horizontally and is located on the two columns (783); the push plate (785) is placed vertically and forms an inverted L-shaped structure with the pressure plate (784); the push plate (785) is located between the two columns (783) and the rectangular bottom plate (782); a circular through hole (786) is opened in the middle of the push plate (785); and a gap is left between the pressure plate (784) and the horizontal plate (788).

3. The Fiber Bragg Grating top plate delamination monitoring device according to claim 2, characterized in that: A second magnet (781) is provided at the bottom of the horizontal plate (788) outside the vertical plate (787), and the second magnet (781) is located directly above the rotating tooth (721). The rotating tooth (721) is made of magnetic material, and the magnetic poles of two adjacent teeth are different.

4. The Fiber Bragg Grating top plate delamination monitoring device according to claim 2, characterized in that: Two gaskets (8) are provided on the top of the transverse plate (788) outside the vertical plate (787), and the two gaskets (8) are symmetrically located on both sides of the optical fiber grating (6).

5. The Fiber Bragg Grating top plate delamination monitoring device according to claim 2, characterized in that: A plurality of grids are symmetrically arranged on both sides of the optical fiber grating (6), and the plurality of grids are respectively located on the T-shaped elastic plate (771), the fixing plate (77), the pressure plate (784) and the transverse plate (788).

6. The Fiber Bragg Grating top plate delamination monitoring device according to claim 2, characterized in that: The pressure plate (784) and the push plate (785) are integrally formed, and the upright column (783) is made of elastic material.

7. The fiber grating top plate delamination monitoring device according to claim 2, characterized in that: The optical fiber Bragg grating (6) is respectively connected to the T-shaped elastic plate (771), the pressure plate (784) and the transverse plate (788) via a polymer adhesive.

8. A delamination monitoring method using a fiber grating top plate delamination monitoring device according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: Conduct a calibration experiment in the laboratory to calculate the conversion coefficient between the displacement of the surrounding rock layer and the central wavelength offset of the fiber Bragg grating (6) of the monitoring device after temperature compensation, and calculate the linear regression errors of the three observation points respectively; S2: Drilling a hole on site in the tunnel, installing a separation monitoring device, fixing two anchor claws (1) in the deep and shallow rock layers respectively, inserting a casing (4) into the drill hole and fixing it with a steel claw, and connecting the fiber Bragg grating (6) to a demodulator; S3: As the surrounding rock moves inside, the anchor claw (1) drives the screw rod (72) to rotate by pulling the rope (3), thereby driving the slider (76) to move on the base (74); the movement of the slider (76) drives the T-shaped elastic plate (771) to move on the top of the No. 1 magnet (75), and the magnetic force between the T-shaped elastic plate (771) and the No. 1 magnet (75) changes. As the T-shaped elastic plate (771) moves away from the No. 1 magnet (75), the magnetic force decreases, and the fiber grating (6) is deformed along with the T-shaped elastic plate (771); When the slider (76) moves, it pushes the compression spring (79), the compression spring (79) is compressed, and pushes the push plate (785) to move, and when the push plate (785) moves on the column (783), it drives the side of the pressure plate (784) close to the horizontal plate (788) to move upward, so that the pressure plate (784) drives the optical fiber Bragg grating (6) to deform; When the screw rod (72) rotates, it drives the rotating tooth (721) to rotate, and the magnetic force between the rotating tooth (721) and the second magnet (781) changes, causing the horizontal plate (788) on the vertical plate (787) to move up and down, and driving the optical fiber grating (6) to deform; S4: The three points are used to measure the change caused by the central wavelength deviation of the fiber Bragg grating (6) at the same time. The value of each measuring point of the fiber Bragg grating (6) is converted into the surrounding rock displacement according to the conversion coefficient calculated in step S1. The data sets of the three measuring points on one side are respectively x i ,y i , z i , the following correlation coefficient is used to calculate the correlation between the data of the three measuring points on one side of the device after temperature compensation: ， ， ； S5: Analyze the correlation results. If r xy , r yz , r xz If all three are greater than 0.8 and less than or equal to 1, the final measurement output is the displacement value calculated by the fiber Bragg grating (6) with the smallest linear regression error in step S1; if r xy , r yz , r xz If only one value is greater than 0.8 and less than or equal to 1, and the output results of the two grids represented by the value change dynamically, the displacement value calculated by the fiber Bragg grating (6) with the smaller linear regression error in the two grids represented by the value is selected as the output, and the other fiber Bragg grating (6) is judged to be faulty; if r xy , r yz , r xz If all three are less than 0.8, it is judged to be a structural failure or a fiber Bragg grating (6) failure and repair is performed.

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