Optical fiber grating roof separation monitoring device and method

Abstract

The present invention relates to the technical field of roadway surrounding rock monitoring, and specifically relates to an optical fiber grating roof separation monitoring device and a method. The device comprises anchor claws, a housing, ropes, a sleeve, a protective box, and an optical fiber grating, and further comprises a movement detection mechanism. The movement detection mechanism comprises a reel, a lead screw, a base, a first magnet, a recessed block, a sliding block, a fixed plate, an elastic frame, rotating teeth, and a compression spring. The present invention solves the problem of reduction of the monitoring accuracy due to loosening and falling off of bonding points, and damage to sensitive elements caused by fatigue stress in the monitoring process of the existing optical fiber grating monitoring device, and realizes redundancy configuration of signals during monitoring, thereby greatly improving the accuracy and reliability of the optical fiber grating roof separation monitoring device.

Description

A fiber optic grating top plate delamination monitoring device and method Technical Field

[0001] This invention belongs to the field of tunnel surrounding rock monitoring technology, specifically relating to a fiber optic grating roof delamination monitoring device and method. Background Technology

[0002] In modern coal mining, roof stability is one of the key factors ensuring safe production. Monitoring roof delamination is crucial for early warning of roadway collapses and ensuring miner safety. Currently, the most common monitoring method both domestically and internationally is the installation of roof delamination meters based on electrical sensing methods. However, in practical applications, these meters face problems such as poor durability, weak anti-interference capabilities, and limited signal transmission distance. Especially in the high-temperature and high-humidity environment of underground coal mines, the aging of devices is accelerated, easily causing sensor malfunctions.

[0003] In recent years, the research and application of fiber Bragg grating (FBG) sensing technology has attracted widespread attention. Compared with traditional sensing and measurement technologies, FBG sensing has many significant advantages, such as resistance to moisture, corrosion, and interference, and ease of constructing sensor networks. Currently, FBG sensing technology has been applied to the measurement of state quantities such as anchor bolt stress and surrounding rock displacement in coal mines. However, during long-term service, fatigue stress in FBG sensing devices can easily lead to loosening and detachment of bonding points and damage to the sensing element, thereby reducing the reliability of the measurement.

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

[0005] The purpose of this invention is to solve the problem that the monitoring accuracy of existing fiber Bragg grating monitoring devices is reduced due to fatigue stress, loosening and falling off of adhesive points, and damage to sensitive elements during the monitoring process. This invention achieves redundant configuration of signals during monitoring, which greatly improves the accuracy and reliability of the fiber Bragg grating top plate delamination monitoring device.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A fiber Bragg grating top plate delamination monitoring device includes an anchor claw, a housing, a rope, a sleeve, a protective box, and a fiber Bragg grating; the housing is connected to the anchor claw via the rope; a sleeve is provided on the top of the housing, and the sleeve is fitted over the outside of the rope; the protective box is located on both sides of the housing, and the fiber Bragg grating passes through the protective box and the inside of the housing in sequence;

[0008] It also includes: a mobile detection mechanism, which is located inside the outer casing and the protective box;

[0009] The mobile detection mechanism includes: a drum, a lead screw, a coil spring, a base, a first magnet, a concave block, a slider, a fixed plate, an elastic frame, rotating teeth, and a compression spring;

[0010] The drum contains a lead screw and a coil spring on its outer side. The drum is located inside the outer casing and is connected to the rope. The base is located inside the protective box. A concave block, a slider, and an elastic frame are arranged sequentially on the base. A compression spring is provided between the slider and the elastic frame. A magnet is located on the top of the concave block. A fixing plate is located on the top of the slider. A T-shaped elastic plate extending outward is provided on the side of the fixing plate near the concave block. The T-shaped elastic plate is located above the magnet. The lead screw passes sequentially through the concave block, the slider, the compression spring, and the elastic frame, and the end of the lead screw has rotating teeth.

[0011] Preferably, the elastic frame includes: a rectangular base plate, columns, pressure plates, push plates, vertical plates, horizontal plates, and stiffening plates;

[0012] The rectangular base plate is mounted on the base, with a gap between it and the two columns; the columns and the rectangular base plate form an L-shaped structure; stiffening ribs are arranged between the columns and the rectangular base plate; a horizontal plate is provided at the top of the columns;

[0013] The rectangular base plate has two columns, the pressure plate is arranged horizontally and located on the two columns, the push plate is placed vertically and forms an inverted L-shaped structure with the pressure plate, and the push plate is located between the two columns and the rectangular base plate; the push plate has a circular through hole in the middle, and a gap is left between the pressure plate and the horizontal plate.

[0014] Preferably, a second magnet is provided at the bottom of the horizontal plate on the outer side of the upright plate, and the second magnet is located directly above the rotating tooth. The rotating tooth is made of magnetic material, and the magnetic poles between adjacent teeth are different.

[0015] Preferably, two pads are provided on the top of the horizontal plate on the outer side of the vertical plate, and the two pads are symmetrically located on both sides of the fiber optic grating.

[0016] Preferably, multiple grids are symmetrically arranged on both sides of the fiber optic grating, and the multiple grids are respectively located on the T-shaped elastic plate, the fixed plate, the pressure plate and the horizontal plate.

[0017] Preferably, the pressure plate and the push plate are integrally formed, and the column is made of elastic material.

[0018] Preferably, the fiber grating is connected to the T-shaped elastic plate, the pressure plate, and the cross plate respectively by a polymer adhesive.

[0019] A delamination monitoring method for a fiber optic grating top plate delamination monitoring device includes the following steps:

[0020] S1: Conduct calibration experiments in the laboratory, calculate the conversion coefficient between the surrounding rock delamination displacement and the center wavelength shift of the fiber optic grating of the monitoring device after temperature compensation, and calculate the linear regression error at the three observation points respectively.

[0021] S2: Drill holes in the roadway, install the delamination monitoring device, fix two anchor claws to the deep and shallow rock layers respectively, insert the casing into the borehole and fix it with steel claws, and connect the fiber optic grating to the demodulator.

[0022] S3: As the surrounding rock moves inside, the anchor claw pulls the rope to drive the screw to rotate, which in turn moves the slider on the base. The slider moves the T-shaped elastic plate to move on top of the No. 1 magnet. 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 optic grating deforms along with the T-shaped elastic plate.

[0023] As the slider moves, it pushes the compression spring, which is compressed and pushes the push plate to move. As the push plate moves on the column, it drives the pressure plate to move upward on the side closest to the horizontal plate, causing the pressure plate to deform the fiber grating.

[0024] When the lead screw rotates, it drives the rotating teeth to rotate. 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 causing the fiber grating to deform.

[0025] S4: Simultaneously measure the change caused by the center wavelength shift of the fiber optic grating at three points. Based on the conversion coefficient calculated in step S1, convert the values ​​of each measuring point of the fiber optic grating into the surrounding rock displacement. Let the datasets of the three measuring points on one side be x. i y i , z i The correlation coefficients were used to calculate the pairwise correlation between the data from the three measuring points on one side of the device after temperature compensation:

[0026] S5: Analyze the correlation results; if r xy r yz r xz If all three values ​​are greater than 0.8 and less than or equal to 1, then the final measurement output is the displacement value calculated by the fiber 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 gratings represented by this value change dynamically, then the displacement value calculated by the fiber grating with the smaller linear regression error among the two gratings represented by this value is selected as the output, and the other fiber grating is determined to be faulty; if r xy ryz r xz If all three values ​​are less than 0.8, it is determined to be a structural fault or a fiber optic grating fault, and repairs should be carried out.

[0027] The beneficial effects of this invention are:

[0028] 1. This invention utilizes a rope-driven, coordinated mobile detection mechanism to detect rock strata. The mobile detection mechanism simultaneously detects multiple points of the fiber Bragg grating, ensuring signal redundancy during dynamic monitoring. When surrounding rock deformation causes displacement of the internal structure of the device, the wavelength of the fiber Bragg grating changes. Through temperature compensation and correlation analysis, effective fault signal location is achieved, and valid measurement results are output, significantly improving the accuracy and reliability of the fiber Bragg grating top plate delamination monitoring device.

[0029] 2. The present invention provides a fixing plate and a first magnet on the lead screw. By changing the distance between the fixing plate and the first magnet, the magnetic force between them is changed, which causes the fixing plate and the fiber grating bonded to the top to deform, thereby changing the wavelength of the fiber grating transmission and improving the accuracy of top plate delamination monitoring.

[0030] 3. The present invention uses a slider on a lead screw to slide and push a push plate on an elastic frame, which causes the push plate to move and deform the fiber optic grating, thereby changing the wavelength of the fiber optic grating and thus improving the accuracy of top plate delamination monitoring.

[0031] 4. This invention uses the rotation of the lead screw to drive the rotating teeth on the end of the lead screw to rotate, and changes the distance between the rotating teeth and the second magnet, causing the horizontal plate on the outer side of the vertical plate to vibrate, and causing the fiber optic grating to deform, thereby changing the wavelength transmitted by the fiber optic grating and thus improving the accuracy of top plate delamination monitoring. Attached Figure Description

[0032] Figure 1 is an exploded view of the entire invention;

[0033] Figure 2 is an enlarged view of point A in Figure 1 of this invention;

[0034] Figure 3 is an enlarged view of point B in Figure 2 of this invention;

[0035] Figure 4 is a three-dimensional structural diagram of the elastic frame of the present invention;

[0036] Figure 5 is a three-dimensional structural diagram of the inside of the roll of the present invention;

[0037] In the diagram: 1. Anchor claw; 2. Outer shell; 3. Rope; 4. Sleeve; 5. Protective box; 6. Fiber optic grating; 7. Motion detection mechanism; 71. Drum; 72. Lead screw; 721. Rotating gear; 73. Coil spring; 74. Base; 75. Magnet No. 1; 751. Concave block; 76. Slider; 77. Fixing plate; 771. T-shaped elastic plate; 78. Elastic frame; 781. Magnet No. 2; 782. Rectangular base 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 Implementation

[0038] The method of using the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0039] As shown in Figures 1 to 5, a fiber Bragg grating top plate delamination monitoring device includes an anchor claw 1, a housing 2, a rope 3, a sleeve 4, a protective box 5, and a fiber Bragg grating 6. The housing 2 is connected to the anchor claw 1 via the rope 3. The top of the housing 2 is provided with a sleeve 4, which is sleeved on the outside of the rope 3. The protective box 5 is provided on both sides of the housing 2, and the fiber Bragg grating 6 passes through the protective box 5 and the interior of the housing 2 in sequence.

[0040] It also includes: a mobile detection mechanism 7, which is located inside the outer shell 2 and the protective box 5; the mobile detection mechanism 7 is moved by the pulling of the rope 3, and the fiber optic grating 6 is squeezed and deformed, thereby changing the wavelength transmitted by the fiber optic grating 6.

[0041] As shown in Figures 2 to 5, the moving detection mechanism 7 includes: a drum 71, a lead screw 72, a coil spring 73, a base 74, a first magnet 75, a concave block 751, a slider 76, a fixing plate 77, an elastic frame 78, a rotating tooth 721, and a compression spring 79.

[0042] The drum 71 contains a lead screw 72, and a coil spring 73 is provided on the outside of the drum 71. The drum 71 fixes one end of the lead screw 72, and the outside of the drum 71 is used to install the coil spring 73. During resetting, the coil spring 73 rotates, causing the drum 71 to rotate inside the outer casing 2, thereby causing the lead screw 72 to rotate and reset. The drum 71 is located inside the outer casing 2 and is connected to the rope 3. The base 74 is located inside the protective box 5. A concave block 751, a slider 76, and an elastic frame 78 are arranged sequentially on the base 74. A compression mechanism is provided between the slider 76 and the elastic frame 78. Spring 79, compression spring 79 can be used to drive slider 76 to reset. The top of the concave block 751 is provided with a first magnet 75. The top of the slider 76 is provided with a fixing plate 77. The fixing plate 77 can be connected to the top of the slider 76 by bolts. The side of the fixing plate 77 near the concave block 751 is provided with an outwardly extending T-shaped elastic plate 771. The T-shaped elastic plate 771 is located above the first magnet 75. The lead screw 72 passes through the concave block 751, slider 76, compression spring 79 and elastic frame 78 in sequence, and the end of the lead screw 72 is provided with a rotating tooth 721.

[0043] It should be noted that the distance between the top of the first magnet 75 and the bottom of the T-shaped elastic plate 771 is between 2mm and 5mm. As the slider 76 moves the T-shaped elastic plate 771, the magnetic force between the T-shaped elastic plate 771 and the first magnet 75 will change, thereby causing the T-shaped elastic plate 771 to deform the fiber optic grating 6.

[0044] It should be noted that the T-shaped elastic plate 771 is initially bent upwards, and the fiber optic grating 6 is attached above the T-shaped elastic plate 771. When the T-shaped elastic plate 771 is directly above the first magnet 75, the T-shaped elastic plate 771 will deform from the bent state to the horizontal state due to the magnetic attraction force. At this time, the fiber optic grating 6 above the T-shaped elastic plate 771 will not change. When the slider moves the T-shaped elastic plate 771 towards the elastic frame 78, the distance between the T-shaped elastic plate 771 and the first magnet 75 will increase, the magnetic force will weaken, and thus the T-shaped elastic plate 771 will cause the fiber optic grating 6 to deform.

[0045] As shown in Figure 4, the elastic frame 78 includes: a rectangular base plate 782, columns 783, a pressure plate 784, a push plate 785, a vertical plate 787, a horizontal plate 788, and a stiffening plate 789; the rectangular base plate 782 is disposed on the base 74, and a gap is left between the two columns 783 and the rectangular base plate 782; the vertical plate 787 and the rectangular base plate 782 form an L-shaped structure; the stiffening plate 789 is arranged between the vertical plate 787 and the rectangular base plate 782; a horizontal plate 788 is provided at the top of the vertical plate 787;

[0046] The rectangular base plate 782 is provided with two columns 783. 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. The push plate 785 is located between the two columns 783 and the rectangular base plate 782. A circular through hole 786 is opened in the middle of the push plate 785. A gap is left between the pressure plate 784 and the horizontal plate 788.

[0047] The gap between the pressure plate 784 and the horizontal plate 788 is to ensure that when the pressure plate 784 deforms, it will not interfere with the horizontal plate 788, and there is enough space for the pressure plate 784 to drive the fiber grating 6 to deform.

[0048] As shown in Figures 2 and 3, a second magnet 781 is provided at the bottom of the horizontal plate 788 on the outer side of 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 between two adjacent teeth are different.

[0049] 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 changes, thereby causing the horizontal plate 788 to move up and down and causing the fiber optic grating 6 to deform.

[0050] 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 also changes accordingly, causing the horizontal plate 788 to move up and down and causing the fiber optic grating 6 to deform.

[0051] As shown in Figure 2, two pads 8 are provided on the top of the horizontal plate 788 on the outer side of the vertical plate 787, and the two pads 8 are symmetrically located on both sides of the fiber optic grating 6.

[0052] The fiber optic grating 6 has multiple grids symmetrically arranged on both sides, and the multiple grids are respectively located on the T-shaped elastic plate 771, the fixed plate 77, the pressure plate 784 and the horizontal plate 788.

[0053] It should be noted that the grid fixed to the fixed plate 77 is not affected by force and is used for temperature compensation, because temperature will cause wavelength changes, and there needs to be a force-free grid to compensate for the influence of ambient temperature.

[0054] 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 will drive the pressure plate 784 to move upward, and the connection between the column 783 and the pressure plate 784 will undergo elastic deformation. When the push plate 785 is no longer under force, it will return to its original position through elastic force.

[0055] The fiber Bragg grating 6 is connected to the T-shaped elastic plate 771, the pressure plate 784, and the horizontal plate 788 respectively by 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 horizontal plate 788, so that when deformation occurs, the fiber Bragg grating 6 can deform together with them.

[0056] A delamination monitoring method for a fiber Bragg grating 6 top plate delamination monitoring device includes the following steps:

[0057] S1: Conduct calibration experiments in the laboratory, calculate the conversion coefficient between the surrounding rock delamination displacement and the center wavelength shift of the fiber optic grating 6 of the monitoring device after temperature compensation, and calculate the linear regression error at the three observation points respectively.

[0058] S2: Drill holes in the roadway, install a delamination monitoring device, fix two anchor claws 1 to the deep and shallow rock layers respectively, insert the casing 4 into the drill hole and fix it with steel claws, and connect the fiber optic grating 6 to the demodulator.

[0059] S3: As the surrounding rock moves inside, the anchor claw 1 pulls the rope 3 to drive the screw 72 to rotate, which in turn drives the slider 76 to move on the base 74. The movement of the slider 76 causes the T-shaped elastic plate 771 to move on top of the first magnet 75. The magnetic force between the T-shaped elastic plate 771 and the first magnet 75 changes. As the T-shaped elastic plate 771 moves away from the first magnet 75, the magnetic force decreases, and the fiber optic grating 6 deforms along with the T-shaped elastic plate 771.

[0060] As the slider 76 moves, it pushes the compression spring 79. The compression spring 79 is compressed and pushes the push plate 785 to move. As 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, causing the pressure plate 784 to deform the fiber optic grating 6.

[0061] When the lead screw 72 rotates, it drives the rotating tooth 721 to rotate. 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 causing the fiber optic grating 6 to deform.

[0062] S4: Simultaneously measure the change caused by the center wavelength shift of fiber optic grating 6 at three points. Based on the conversion coefficient calculated in step S1, convert the values ​​of each measuring point of fiber optic grating 6 into surrounding rock displacement. Let the datasets of the three measuring points on one side be x. i y i , z i The correlation coefficients were used to calculate the pairwise correlation between the data from the three measuring points on one side of the device after temperature compensation:

[0063] S5: Analyze the correlation results; if r xyr yz r xz If all three values ​​are greater than 0.8 and less than or equal to 1, then the final measurement output is the displacement value calculated by fiber grating 6, which has 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 gratings represented by this value change dynamically, then the displacement value calculated by fiber grating 6 with the smaller linear regression error among the two gratings represented by this value is selected as the output, and the other fiber grating 6 is determined to be faulty; if r xy r yz r xz If all three values ​​are less than 0.8, it is determined to be a structural fault or a fiber optic grating 6 fault, and repairs should be carried out.

[0064] Working process: Anchor claw 1 is driven into and fixed inside the rock layer, and is connected to anchor claw 1 through rope 3 in sleeve 4. When the rock layer is loosened, it drives anchor claw 1 to move. Anchor claw 1 will pull drum 71 to rotate. Drum 71 drives screw 72 to rotate. At the same time, the rotation of drum 71 drives coil spring 73 to contract. The rotation of screw 72 will drive slider 76 to move outward on base 74. T-shaped elastic plate 771 on the side of fixed plate 77 on top of slider 76 near magnet 75 is located directly above magnet 75. As fixed plate 77 moves away from magnet 75, the magnetic force between T-shaped elastic plate 771 and magnet 75 decreases. T-shaped elastic plate 771 will deform and drive fiber optic grating 6 on top of T-shaped elastic plate 771 to deform along with T-shaped elastic plate 771.

[0065] Meanwhile, as the slider 76 moves, it will push the compression spring 79, which will be compressed and push the push plate 785 to move. As the bottom end of the push plate 785 moves outward on the column 783, it will drive the pressure plate 784 to move upward on the side close to the horizontal plate 788, causing the pressure plate 784 to deform the fiber optic grating 6.

[0066] Furthermore, when the lead screw 72 rotates, it will drive the rotating tooth 721 at the end of the lead screw 72 to rotate. Due to the different tooth pitch on the rotating tooth 721, the distance between the rotating tooth 721 and the second magnet 781 will also change, and the magnetic force between the two will change, thereby causing the horizontal plate 788 on the outside of the vertical plate 787 to move up and down, and causing the fiber optic grating 6 to deform.

[0067] Through the symmetrically arranged grids on both sides of the fiber optic grating 6, various different grids can reflect eight wavelengths of light: 1530nm, 1535nm, 1540nm, 1545nm, 1550nm, 1555nm, 1560nm, and 1565nm. As the sensing structure undergoes slight deformation, it will cause the center wavelength of the reflected light at the corresponding measurement point to shift. That is, the deformation of the measurement point can be calculated from the change in wavelength. The change in the center wavelength offset of the fiber optic grating 6 is measured at three points simultaneously. After temperature compensation, the conversion coefficient between the surrounding rock delamination displacement and the center wavelength offset of the fiber optic grating 6 is calculated, and the values ​​of each measurement point of the fiber optic grating 6 are converted into the surrounding rock displacement.

[0068] It should be noted that: a calibration experiment needs to be conducted in the laboratory first to calculate the conversion coefficient between the surrounding rock delamination displacement and the center wavelength shift of the fiber optic grating 6 of the monitoring device after temperature compensation, and to calculate the linear regression error at the three observation points respectively.

[0069] When the center wavelength of fiber grating 6 changes, the values ​​of each measuring point of fiber 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.

[0070] Finally, the correlation results are analyzed. If all three correlation coefficients are greater than 0.8 and less than or equal to 1, the final measurement output is the displacement value calculated by the fiber 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 grating 6 with the smaller linear regression error among the two sensors represented by this value is selected as the output, and the other fiber grating 6 is determined to be faulty. If all three correlation coefficients are less than 0.8, it is determined to be a structural fault or a faulty fiber grating 6, and repair is carried out.

[0071] Finally, it should be noted that the above are merely 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 foregoing embodiments or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fiber Bragg grating top plate delamination monitoring device, comprising an anchor claw (1), a housing (2), a rope (3), a sleeve (4), a protective box (5), and a fiber Bragg grating (6); the housing (2) is connected to the anchor claw (1) via the rope (3); the housing (2) is provided with a sleeve (4) at the top, and the sleeve (4) is sleeved on the outside of the rope (3); the protective box (5) is provided on both sides of the housing (2), and the fiber Bragg grating (6) passes through the protective box (5) and the interior of the housing (2) in sequence; Its features are, It also includes: a mobile detection mechanism (7), which is located inside the outer casing (2) and the protective box (5); The moving detection mechanism (7) includes: a drum (71), a lead screw (72), a coil spring (73), a base (74), a first magnet (75), a concave block (751), a slider (76), a fixing plate (77), an elastic frame (78), a rotating tooth (721), and a compression spring (79); The drum (71) is equipped with a lead screw (72), and a coil spring (73) is provided on the outside of the drum (71). The drum (71) is located inside the outer shell (2) and is connected to the rope (3). The base (74) is located inside the protective box (5). A concave block (751), a slider (76), and an elastic frame (78) are arranged sequentially on the base (74). A compression spring (79) is provided between the slider (76) and the elastic frame (78). The concave block (751)... 1) A magnet (75) is provided at the top, and a fixing plate (77) is provided at the top of the slider (76). The fixing plate (77) has an outwardly extending T-shaped elastic plate (771) on the side near the concave block (751). The T-shaped elastic plate (771) is located above the 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 the end of the lead screw (72) is provided with a rotating tooth (721).

2. The fiber optic grating top plate delamination monitoring device according to claim 1, characterized in that, The elastic frame (78) includes: a rectangular base plate (782), a column (783), a pressure plate (784), a push plate (785), a vertical plate (787), a horizontal plate (788), and a stiffening plate (789); The rectangular base plate (782) is mounted on the base (74) and has a gap between it and the two columns (783). The upright plate (787) and the rectangular base plate (782) form an L-shaped structure. Ribs (789) are arranged between the upright plate (787) and the rectangular base plate (782). A horizontal plate (788) is provided at the top of the upright plate (787). The rectangular base plate (782) is provided with two columns (783), 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), the push plate (785) is located between the two columns (783) and the rectangular base 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 optic grating top plate delamination monitoring device according to claim 2, characterized in that: The bottom of the horizontal plate (788) on the outer side of the vertical plate (787) is provided with a second magnet (781), 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 between two adjacent teeth are different.

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

5. The fiber optic grating top plate delamination monitoring device according to claim 2, characterized in that: The fiber grating (6) has multiple grids symmetrically arranged on both sides, and the multiple grids are located on the T-shaped elastic plate (771), the fixed plate (77), the pressure plate (784) and the horizontal plate (788), respectively.

6. The fiber optic 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 column (783) is made of elastic material.

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

8. A delamination monitoring method according to a fiber optic grating top plate delamination monitoring device as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1: Conduct calibration experiments in the laboratory, calculate the conversion coefficient between the displacement of the surrounding rock delamination and the center wavelength shift of the fiber optic grating (6) of the monitoring device after temperature compensation, and calculate the linear regression error of the three observation points respectively. S2: Drill holes in the roadway, install a separation monitoring device, fix two anchor claws (1) to the deep and shallow rock layers respectively, insert the casing (4) into the borehole and fix it with steel claws, and connect the fiber optic grating (6) to the demodulator. S3: As the surrounding rock moves inside, the anchor claw (1) pulls the rope (3) to drive the screw (72) to rotate, which in turn drives the slider (76) to move on the base (74); the movement of the slider (76) causes the T-shaped elastic plate (771) to move on top of the first magnet (75), and the magnetic force between the T-shaped elastic plate (771) and the first magnet (75) changes. As the T-shaped elastic plate (771) moves away from the first magnet (75), the magnetic force decreases, and the fiber optic grating (6) deforms along with the T-shaped elastic plate (771); As the slider (76) moves, it pushes the compression spring (79), which is compressed and pushes the push plate (785) to move. As 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), causing the pressure plate (784) to deform the fiber grating (6). When the lead screw (72) rotates, it drives the rotating tooth (721) to rotate. 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 causing the fiber optic grating (6) to deform. S4: Simultaneously measure the change caused by the center wavelength shift of the fiber optic grating (6) at three points. Based on the conversion coefficient calculated in step S1, convert the values ​​of each measuring point of the fiber optic grating (6) into the surrounding rock displacement. Let the datasets of the three measuring points on one side be x. i y i , z i The correlation coefficients were used to calculate the pairwise correlation between the data from 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 values ​​are greater than 0.8 and less than or equal to 1, then the final measurement output is the displacement value calculated by the fiber 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 gratings represented by this value change dynamically, then the displacement value calculated by the fiber grating (6) with the smaller linear regression error among the two gratings represented by this value is selected as the output, and the other fiber grating (6) is determined to be faulty; if r xy r yz r xz If all three values ​​are less than 0.8, it is determined to be a structural fault or a fiber optic grating (6) fault, and repairs should be carried out.

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