Coal mine tunnel roof displacement monitoring device

Abstract

The invention discloses a coal mine tunnel roof displacement monitoring device, and belongs to the technical field of tunnel roof displacement monitoring, grooves are etched in the outer surface of an anchor rod body through an ultrafast laser micro-nano machining technology, the grooves are spirally distributed, graphene sensing fibers and flexible optical fiber spiral layers are embedded in the grooves, and the graphene sensing fibers and the flexible optical fiber spiral layers are arranged on the outer surface of the anchor rod body. The graphene sensing fiber and the flexible optical fiber spiral layer are used for monitoring the wide area of stress distribution on the surface of the anchor rod body, and the outer surface of the anchor rod body is coated with a nanocapsule filling type self-repairing coating. And the nanocapsule in the nanocapsule filling type self-repairing coating is broken to release the silane repairing agent to repair the crack surface. The spiral groove is etched in the anchor rod body, and the graphene sensing fiber and the flexible optical fiber spiral layer are embedded, so that the stress distribution and stress change of the surface of the anchor rod body can be monitored in a wide area, accurate data are provided for top plate displacement monitoring, and the monitoring accuracy and continuity are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of roadway roof displacement monitoring, and in particular relates to a coal mine roadway roof displacement monitoring device. Background Art

[0002] With the increase in coal mining depth, some mine tunnels show significant plastic deformation and damage characteristics such as large deformation, high ground pressure, and difficulty in support. The rock layers on the roof and floor of many tunnels show soft rock characteristics, which often leads to serious deformation of the tunnel. The displacement of the tunnel roof is the key object of mine monitoring. It can intuitively reflect the strength of the mine pressure on the stress of the tunnel roof, especially in the working face mining stage. The tunnel is greatly affected by mining and is prone to tunnel roof sinking, which reduces the cross-sectional space of the tunnel and seriously affects the normal use of the tunnel.

[0003] Existing methods for measuring tunnel roof displacement mostly rely on manual measurement with a ruler. The tunnel deformation is small and not very noticeable in a short period of time. Manual observation results in large errors and cannot be processed in a timely manner. Furthermore, deformation data is difficult to collect and analyze, and has significant limitations, failing to fully reflect the tunnel's stress conditions. Currently, tunnel monitoring generally relies on manual measurement and recording, with specific workers using measuring devices to perform measurements and record data at regular intervals. This wastes a significant amount of manpower and material resources, results in inaccurate measurement results, and makes real-time monitoring difficult. Furthermore, the entire process of tunnel deformation and damage cannot be effectively captured. Summary of the Invention

[0004] The purpose of the present invention is to provide a coal mine roadway roof displacement monitoring device to solve the problems raised in the above background technology.

[0005] To achieve the above objectives, the present invention provides the following technical solutions: a coal mine roadway roof displacement monitoring device, comprising a roof and an anchor body, wherein a borehole is formed in the roof, and the anchor body is inserted into the borehole. The outer surface of the anchor body is etched with grooves using ultrafast laser micro-nano processing technology, and the grooves are distributed in a spiral shape. A graphene sensing fiber and a flexible optical fiber helical layer are embedded in the grooves, and the graphene sensing fiber and the flexible optical fiber helical layer are used to monitor the wide area of ​​stress distribution on the surface of the anchor body;

[0006] The outer surface of the anchor body is covered with a nanocapsule-filled self-repairing coating. When microcracks are generated on the surface of the anchor body due to stress, the nanocapsules in the nanocapsule-filled self-repairing coating rupture and release silane repair agent to repair the crack surface.

[0007] In the above implementation process, a pre-drilled hole is pre-drilled in the top plate, and the anchor body is securely inserted into the hole by tightening a nut. Ultrafast laser micro-nano processing technology is used to meticulously etch spiral grooves on the outer surface of the anchor body. A graphene sensing fiber and a helical layer of flexible optical fiber are embedded in the shallow grooves and spirally wound along the anchor axis. When the top plate shifts, the anchor is pulled, causing the resistance of the graphene fiber to change. This is converted into a digital signal by a bridge circuit to sense local strain. The flexible optical fiber transmits the optical signal and resists electromagnetic interference. The two work together to achieve wide-area monitoring of the surface stress distribution of the anchor body, enabling extensive and accurate monitoring of the surface stress distribution of the anchor body, thereby indirectly obtaining roof displacement information. Simultaneously, the outer surface of the anchor body is coated with a nanocapsule-filled self-healing coating. When microcracks appear on the anchor body due to stress generated by roof displacement, the nanocapsules in the nanocapsule-filled self-healing coating rupture and release a silane healing agent. When the silane healing agent encounters a catalyst in the coating, a cross-linking and curing reaction occurs, repairing the crack surface and achieving self-repair of the damaged area.

[0008] In a specific embodiment, a screw is installed on the top of the anchor body, and the outer surface of the screw is threadedly connected to a main connector. The outer surface of the main connector is welded with multiple groups of secondary connectors, and the outer surfaces of the main connector and the secondary connector are embedded with evenly distributed piezoelectric ceramic sheets.

[0009] In the above implementation process, a screw is installed on the top of the anchor body, and the screw is connected to the main connector through a threaded connection, so that the main connector with different numbers of secondary connectors can be replaced conveniently according to actual usage and rock conditions. When the roof of the coal mine tunnel is displaced, the anchor body is subjected to force and vibrates. This vibration is transmitted to the main connector and the secondary connector, causing the piezoelectric ceramic piece to undergo mechanical deformation, thereby generating an electrical signal. By collecting, analyzing and processing these electrical signals, relevant information about the roof displacement, such as the amplitude and frequency of the displacement, can be obtained. By welding multiple secondary connectors on the main connector, vibrations of different directions and degrees can be captured more comprehensively, thereby improving the accuracy and comprehensiveness of monitoring the roof displacement in the mining-affected area.

[0010] In a specific embodiment, the outer surface of the nanocapsule-filled self-healing coating is provided with upper and lower sliding sleeves, and the surfaces of the two groups of sliding sleeves close to each other are provided with symmetrically arranged storage grooves, and the interiors of the four groups of storage grooves are hinged with connecting rods, and one end of the upper and lower groups of connecting rods is hinged with a support plate.

[0011] In the above implementation process, when the top plate undergoes a slight displacement, the upper sliding sleeve will slide downward and push the support plate to expand outward through the connecting rod. The support plate can contact the rock mass around the borehole and play a certain supporting role. At the same time, its movement state can also reflect the displacement of the top plate and provide auxiliary information for monitoring.

[0012] In a specific embodiment, the interior of the anchor rod body is equidistantly distributed with FBG arrays along the axial direction, the outer surface of the bottom end of the anchor rod body is provided with a threaded groove, the outer surface of the threaded groove is threadedly connected with a fastening nut, a monitoring box and a junction box are installed at the bottom of the top plate, and the junction box is located on one side of the monitoring box, the monitoring box and the junction box are connected by a cable, and the bottom end of the FBG array extends into the interior of the monitoring box.

[0013] In the above implementation process, FBG arrays are evenly distributed along the axial direction inside the anchor body. The FBG array can accurately measure the strain on the anchor body. By measuring the wavelength change of the reflected light, the strain data at different positions of the anchor body can be obtained in real time, and the displacement of the roof can be calculated. A threaded groove is provided on the outer surface of the bottom end of the anchor body, and a fastening nut is connected by thread to fix the anchor body in the drilled hole. A monitoring box and a junction box are installed at the bottom of the roof, and the two are connected by a cable. The monitoring box collects multivariate parameters from multiple sensors such as the graphene sensing fiber and the flexible optical fiber spiral layer, the piezoelectric ceramic piece, and the FBG array. A buzzer and a warning light are installed at the bottom of the junction box. When the roof sinks or deforms, the monitoring box transmits a signal to the buzzer, which sounds an alarm and flashes the indicator light. This makes it easier for staff to conduct safety inspections and can quickly and accurately locate the location, allowing staff to take appropriate preventive and treatment measures to avoid safety accidents.

[0014] In a specific embodiment, the spiral pitch of the grooves is dynamically adjusted according to the rock properties of the roadway roof, with the pitch being reduced in hard rock sections and expanded in soft rock sections.

[0015] In the aforementioned implementation process, hard rock typically has high strength and rigidity, which can lead to stress concentration when subjected to mining disturbances. By reducing the helical pitch of the grooves and placing more graphene sensing fibers and flexible optical fiber helical layers on the same length of the anchor bolt, the system can more densely monitor stress changes on the anchor bolt surface in hard rock sections, facilitating the timely detection of potential danger signals. However, compared to hard rock, the deformation of the roadway roof in soft rock sections is generally more uniform and gradual. Increasing the helical pitch of the grooves can appropriately reduce the density of the sensing material and lower costs while ensuring effective monitoring of the stress distribution of the anchor bolt body in soft rock sections. This also avoids the complexity of the sensing signals caused by overly close spacing, facilitating a clearer analysis of stress change trends caused by roof displacement in soft rock sections.

[0016] In a specific embodiment, the secondary connectors are arranged radially to form a spatial stress gradient sensing network.

[0017] In the above implementation process, when the tunnel roof is displaced, the anchor rod body is subjected to force, and the secondary connectors at different positions will feel different stress magnitudes and directions due to differences in spatial positions. Many radially distributed secondary connectors and their piezoelectric ceramic sheets work together to build a three-dimensional stress monitoring network, and at the same time, they can also more comprehensively and accurately perceive the stress gradient changes in the space around the anchor rod. Compared with the monitoring method of a single direction or a more limited distribution, the radially arranged secondary connectors can capture the stress differences caused by the roof displacement on the anchor rod in different directions, and thus more accurately analyze the direction, amplitude and stress concentration area of ​​the roof displacement.

[0018] In a specific embodiment, the outer surface of the nanocapsule-filled self-healing coating is provided with upper and lower baffles, and the top of the lower baffle is in contact with the bottom of the lower sleeve, and the upper baffle is located between the two sets of sleeves. In a free state, the upper sleeve can slide downward and push the support plate to expand outward under the action of the connecting rod.

[0019] In the above implementation process, the baffle is used to limit the sliding sleeve below so that it does not move downward, and the sliding sleeve above can slide downward when the displacement of the top plate changes during subsequent use, and the support plate is expanded outward by the connecting rod so that the support plate can be pressed against the wall of the drilled hole to increase the friction between the support plate and the wall of the drilled hole, and through the setting of the upper baffle, the anchor rod body will not slip between the sliding sleeve, thereby being able to fix the anchor rod body in the drilled hole.

[0020] In a specific embodiment, a data acquisition device and a data processing device are provided inside the monitoring box. The data acquisition device is used to collect multivariate parameters, and the data processing device is used to perform correlation analysis on the collected data, and transmit the processed data and analysis results to the edge server arranged in the explosion-proof chamber at the entrance of the tunnel through the LoRa gateway.

[0021] In the above implementation process, the monitoring box integrates a data acquisition device and a data processing device. The data acquisition device is also used to collect support resistance, roof surrounding rock separation and coal rock support stress data of the working face. The data processing device performs correlation analysis on the large amount of collected data, removes noise and redundant information, and extracts valuable feature data. The processed data and analysis results are transmitted to the edge server arranged in the explosion-proof chamber at the entrance of the tunnel through the LoRa gateway. LoRa communication technology has the characteristics of low power consumption and long-distance transmission, which is suitable for data transmission in the complex environment of coal mines, ensuring that the data can be stably and quickly transmitted to a safe area for subsequent analysis and processing.

[0022] In a specific embodiment, the edge server deploys the ST-CGN algorithm to perform four-dimensional evolution analysis of roof displacement changes.

[0023] In the above implementation process, in the roof displacement monitoring scenario, the ST-CGN algorithm combines the spatial dimension and the temporal dimension, extracts local features in the data through convolution operations, and uses the graph network structure to process the spatial relationship between different sensor nodes, thereby effectively processing the multivariate and dynamic data obtained by roof displacement monitoring, and mining the spatial distribution characteristics of the roof displacement, such as which areas have large displacements, which areas have stress concentrations, and the changing trends over time, whether the displacement is gradually increasing or decreasing, and how the rate of change is to evaluate the stability of the roof, and take support or other preventive measures in time before the roof may be in a dangerous state to ensure safe production in coal mines.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention utilizes ultrafast laser micro-nano processing technology to etch spiral grooves in the anchor body and embed graphene sensing fibers and flexible optical fiber spiral layers. This allows wide-area monitoring of the surface stress distribution of the anchor body, sensitively capturing stress changes, providing accurate data for roof displacement monitoring, and improving monitoring accuracy and sustainability. A nanocapsule-filled self-healing coating automatically repairs microcracks on the anchor body surface, reducing the need to replace new components due to anchor damage. This not only avoids the consumption of raw materials caused by frequent replacement of new anchors, but also improves material utilization efficiency and reduces resource waste at the source. Furthermore, the graphene sensing fibers, flexible optical fibers, and other materials used generate fewer pollutants during production and use than traditional materials, and their stable material performance does not require frequent replacement, thereby reducing waste generation. Accurately monitoring roof displacement and providing early warning of danger can reduce the risk of coal dust and gangue scattering caused by roof accidents, reduce the risk of pollution to the atmosphere, soil, and other environments surrounding the coal mine, and contribute to maintaining the ecological stability of the mining area and its surroundings.

[0026] 2. The present invention provides a detachable main connector, which can fix the main connector welded with different numbers of secondary connectors on the anchor body according to the actual usage scenario. In the subsequent monitoring process, the piezoelectric ceramic pieces on the main connector and the secondary connector can be used to monitor vibrations of different directions and degrees. The electrical signals converted from the vibrations sensed by the piezoelectric ceramic pieces and the stress signals monitored by the graphene sensor fibers complement each other, providing more comprehensive data for roof displacement monitoring, ensuring stable operation of the device, and reducing the risk of resource waste and environmental damage caused by monitoring errors. It can thus accurately monitor roof displacement-related parameters from different angles and multiple dimensions, thereby improving the accuracy and comprehensiveness of roof displacement monitoring in the mining-affected area.

[0027] 3. The present invention not only provides auxiliary support to the top plate to a certain extent through the sliding sleeve and support plate structure, but also can intuitively reflect the displacement changes of the top plate through its own movement state, providing more intuitive reference information for on-site staff. When the top plate is displaced, it can drive the upper sliding sleeve to move downward, so that the support plate fits more closely with the inner wall of the borehole, thereby fixing the anchor rod body in the borehole, preventing the anchor rod body from slipping between the sliding sleeve, and improving the safety of monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0029] Figure 2 This is a schematic diagram of the planar assembly structure of the anchor body and the nanocapsule-filled self-repairing coating of the present invention;

[0030] Figure 3 Schematic diagram of the planar assembly structure of the anchor rod body and the main connector of the present invention;

[0031] Figure 4 Schematic diagram of the planar assembly structure of the anchor body and the FBG array of the present invention;

[0032] Figure 5 It is a schematic diagram of the plane installation of the present invention.

[0033] In the figure: 1. Anchor body; 2. Groove; 3. Graphene sensing fiber and flexible optical fiber spiral layer; 4. Nanocapsule-filled self-healing coating; 5. FBG array; 6. Threaded groove; 7. Fastening nut; 8. Monitoring box; 9. Junction box; 10. Screw; 11. Main connector; 12. Secondary connector; 13. Piezoelectric ceramic sheet; 14. Sleeve; 15. Connecting rod; 16. Support plate. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] See also Figure 1-Figure 5The present invention provides a coal mine tunnel roof displacement monitoring device, comprising a roof and an anchor body 1, a drill hole is opened on the roof, the anchor body 1 is inserted into the drill hole, the outer surface of the anchor body 1 is etched with a groove 2 by ultrafast laser micro-nano processing technology, and the groove 2 is spirally distributed, and a graphene sensing fiber and a flexible optical fiber spiral layer 3 are embedded in the groove 2, and the graphene sensing fiber and the flexible optical fiber spiral layer 3 are used to monitor the wide area of ​​stress distribution on the surface of the anchor body 1, and the outer surface of the anchor body 1 is covered with a nanocapsule filled self-repairing coating 4. When microcracks are generated on the surface of the anchor body 1 due to stress, the nanocapsules The nanocapsules in the filled self-healing coating 4 rupture and release silane repair agent to repair the crack surface. The spiral pitch of the groove 2 is dynamically adjusted according to the rock properties of the tunnel roof. The pitch is reduced in the hard rock section and expanded in the soft rock section. The FBG array 5 is evenly distributed axially inside the anchor body 1. The outer surface of the bottom end of the anchor body 1 is provided with a threaded groove 6. The outer surface of the threaded groove 6 is threadedly connected with a fastening nut 7. A monitoring box 8 and a junction box 9 are installed at the bottom of the top plate, and the junction box 9 is located on one side of the monitoring box 8. The monitoring box 8 and the junction box 9 are connected by a cable, and the bottom end of the FBG array 5 extends into the interior of the monitoring box 8.

[0036] Furthermore, when in use, the assembled anchor body 1 is inserted into the drill hole, and the anchor body 1 is firmly fixed in the drill hole by tightening the nut 7 and cooperating with the thread groove 6. After the anchor body 1 is installed, the monitoring box 8 and the junction box 9 are installed at the bottom of the roof, and the bottom end of the FBG array 5 is connected to the inside of the monitoring box 8. When the roof is deformed, the monitoring box 8 can transmit the signal to the buzzer, thereby sounding an alarm and causing the indicator light to flash, making it easier for staff to conduct safety inspections and enabling rapid and accurate positioning, so that staff can take corresponding preventive and treatment measures. The graphene sensing fiber and the flexible optical fiber helical layer 3 monitor the wide-area stress distribution on the surface of the anchor body 1. By utilizing its high sensitivity to weak stress changes, the surface stress information of the anchor can be accurately captured. The FBG array 5 is equidistantly distributed along the axial direction of the anchor body 1, and can accurately measure the strain conditions at different positions of the anchor, supplementing the stress data from the axial dimension. The two work together to achieve comprehensive monitoring of the stress state of the anchor, thereby accurately reflecting the displacement of the roof.

[0037] The spiral spacing of groove 2 is dynamically adjusted according to the lithology of the roadway roof. The spacing in hard rock sections is reduced, allowing for denser placement of sensors and precise monitoring of complex conditions such as stress concentration in hard rock. The spacing in soft rock sections is increased, meeting monitoring needs while avoiding resource waste and ensuring efficient and accurate monitoring under different lithology conditions.

[0038] The outer surface of the anchor body 1 is covered with a nanocapsule-filled self-healing coating 4. When microcracks are generated on the surface due to stress, the nanocapsules rupture and release silane repair agent to repair the crack surface, which can effectively prevent the anchor body 1 from being damaged by crack expansion, extend the service life of the anchor, ensure the long-term stable operation of the monitoring device, reduce monitoring interruptions caused by component damage, and help ensure the continuity, stability and accuracy of data transmission.

[0039] A screw rod 10 is installed on the top of the anchor rod body 1, and the outer surface of the screw rod 10 is threadedly connected to the main connecting head 11. The outer surface of the main connecting head 11 is welded with multiple groups of secondary connecting heads 12. The outer surfaces of the main connecting head 11 and the secondary connecting heads 12 are embedded with evenly distributed piezoelectric ceramic sheets 13. The secondary connecting heads 12 are radially arranged to form a spatial stress gradient sensing network.

[0040] Furthermore, during use, the main connector 11 welded with different numbers of secondary connectors 12 can be selected according to the actual usage scenario, and installed on the top of the anchor body 1 through the screw 10, and the piezoelectric ceramic piece 13 can be ensured to be firmly installed. When the roof is displaced, the anchor body 1 is subjected to force and vibrates, and the piezoelectric ceramic piece 13 can convert this mechanical vibration into an electrical signal. By analyzing these electrical signals, the amplitude, frequency and other information of the roof displacement can be further understood, providing multi-dimensional data for a comprehensive assessment of the stability of the roof. When a large displacement occurs in a certain direction of the roof, the electrical signal changes generated by the secondary connector 12 and its piezoelectric ceramic piece 13 in the corresponding direction will be more obvious. Through the comprehensive analysis of these electrical signals, more reliable data support can be provided for the assessment of the stability of the coal mine tunnel roof, and potential roof disaster risks can be warned in advance. To a certain extent, it can improve the monitoring device's perception of spatial stress changes and the accuracy and comprehensiveness of roof displacement monitoring.

[0041] The main connector 11 serves as the core node and is connected to the top of the anchor body 1 through threads. The secondary connector 12 is radially welded around the main connector 11 to expand the monitoring coverage and form a spatial stress gradient sensing network, which can capture the non-uniform distribution characteristics of the surrounding rock stress field. Compared with traditional single-point sensors, the main connector 11 and the secondary connector 12 work together to achieve continuous stress monitoring throughout the entire length of the anchor, and the multi-level structural design of the secondary connector 12 can maximize the collection of low-frequency vibration energy in the tunnel, such as coal mining machine vibration and roof fracture shock waves. When the roof is severely deformed, the main connector 11 can transfer the load to the secondary connector 12, and use its flexible welding points to disperse concentrated stress to prevent brittle fracture of the anchor. The monitoring density can be adjusted according to the tunnel width and rock hardness, reducing the number of equipment deployed and saving costs.

[0042] The outer surface of the nanocapsule-filled self-healing coating 4 is provided with upper and lower sleeves 14, and the surfaces of the two groups of sleeves 14 close to each other are provided with symmetrically arranged storage grooves. The interiors of the four groups of storage grooves are hinged with connecting rods 15, and one end of the upper and lower groups of connecting rods 15 is hinged with support plates 16. The outer surface of the nanocapsule-filled self-healing coating 4 is provided with upper and lower baffles, and the top of the lower baffle is in contact with the bottom of the lower sleeve 14, and the upper baffle is located between the two groups of sleeves 14. In the free state, the upper sleeve 14 can slide downward and push the support plate 16 to expand outward under the action of the connecting rod 15.

[0043] Furthermore, when the top plate undergoes a slight displacement, the upper sleeve 14 can slide downward, pushing the support plate 16 to expand outward through the connecting rod 15, and the support plate 16 can fit more closely with the inner wall of the borehole, thereby fixing the anchor rod body 1 in the borehole and preventing the anchor rod body 1 from slipping off the sleeve 14. At the same time, its movement state can also reflect the displacement of the top plate, providing auxiliary information for monitoring.

[0044] The monitoring box 8 is equipped with a data acquisition device and a data processing device. The data acquisition device is used to collect multivariate parameters, and the data processing device is used to perform correlation analysis on the collected data. The processed data and analysis results are transmitted to the edge server arranged in the explosion-proof chamber at the entrance of the tunnel through the LoRa gateway. The edge server deploys the ST-CGN algorithm to perform four-dimensional evolution analysis of the roof displacement changes.

[0045] Furthermore, the data acquisition device is responsible for collecting multivariate parameters from multiple sensors such as the graphene sensing fiber and the flexible optical fiber spiral layer 3, the piezoelectric ceramic piece 13 and the FBG array 5. The multivariate parameters also include the monitoring of the working face support resistance, which is used to analyze the periodic pressure law of the roof and predict possible roof accidents. The roof surrounding rock separation monitoring can dynamically grasp the movement process and law of the roof, thereby facilitating the judgment and identification of the stability of the tunnel. The support stress monitoring of the coal rock is used to analyze the range, intensity and movement direction of the stress field. The data processing device performs correlation analysis on the large amount of collected data, removes noise and redundant information, extracts valuable feature data, and processes the data and analysis. The results are transmitted to the edge server arranged in the explosion-proof chamber at the entrance of the tunnel through the LoRa gateway. By analyzing the data of the anchor bolt position sensors at different times, the dynamic evolution image of the roof displacement over time in three-dimensional space can be drawn, and the development process of the roof displacement can be intuitively displayed. This helps coal mine workers to predict the deformation trend of the roof in advance, evaluate the stability of the roof, and take support or other preventive measures in time before the roof may become dangerous, thereby ensuring the safe production of the coal mine. In addition, through the combination of multiple parameters, multivariate correlation analysis can be carried out to realize online safety monitoring and prediction of the roof of the entire mine, which can improve the in-depth analysis capability of roof displacement data and the accuracy of roof stability assessment to a certain extent.

[0046] The working principle and usage process of the present invention are as follows: during the construction of the roof of a coal mine tunnel, first, a suitable borehole is drilled on the roof according to the design requirements, and the main connector 11 with different numbers of secondary connectors 12 welded thereto is selected according to the actual usage scenario and installed on the top of the anchor body 1 through the screw 10, and the piezoelectric ceramic piece 13 is ensured to be firmly installed to ensure that the device is in normal working condition. Then, the support plate 16 is squeezed inward to move the sliding sleeve 14 upward, and then the anchor body 1 can be inserted into the borehole. By tightening the nut 7 and the threaded groove 6, the anchor body 1 is firmly fixed in the borehole. After the anchor body 1 is installed, the monitoring box 8 and the junction box 9 are installed at the bottom of the roof, and the bottom end of the FBG array 5 is connected to the inside of the monitoring box 8;

[0047] After the monitoring device is installed and put into use, the graphene sensing fiber and the flexible optical fiber spiral layer 3 monitor the surface stress distribution of the anchor body 1 in real time, converting the stress change into an electrical signal or an optical signal. The FBG array 5 accurately obtains the strain data of different positions of the anchor body 1 by measuring the change in the wavelength of the reflected light. When the top plate is displaced, the anchor body 1 is subjected to force and vibrates, and the upper sliding sleeve 14 slides downward, pushing the support plate 16 outward through the connecting rod 15. The support plate 16 contacts the surrounding rock mass, and its motion state can be used as a reference indicator for the displacement of the top plate. At the same time, it cooperates with the set baffle to play a role. The auxiliary support is used to prevent the anchor body 1 from falling out of the drill hole. At the same time, the piezoelectric ceramic piece 13 converts the mechanical vibration of the anchor body 1 into an electrical signal. These multivariate parameters are transmitted to the data acquisition device in the monitoring box 8. The data acquisition device collects and preliminarily processes the data and then transmits it to the data processing device. The data processing device performs correlation analysis on the collected data, removes interference information, and extracts key data related to the roof displacement. The processed data and analysis results are transmitted to the edge server arranged in the explosion-proof chamber at the entrance of the tunnel through the LoRa gateway for management personnel to view and analyze;

[0048] During coal mining, if roof displacement causes excessive stress on the surface of the anchor bolt 1, resulting in microcracks, the nanocapsules in the nanocapsule-filled self-healing coating 4 rupture, releasing a silane repair agent. Under specific conditions, the silane repair agent undergoes a cross-linking and curing reaction, repairing the cracked surface and restoring the anchor bolt 1's strength, allowing it to resume normal operation and ensuring continuous monitoring.

[0049] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A coal mine roadway roof displacement monitoring device, comprising a roof and an anchor body (1), wherein a borehole is provided on the roof, and the anchor body (1) is inserted into the borehole, characterized in that: The outer surface of the anchor rod body (1) is etched with grooves (2) by ultrafast laser micro-nano processing technology, and the grooves (2) are distributed in a spiral shape. Graphene sensing fibers and flexible optical fiber helical layers (3) are embedded in the grooves (2), and the graphene sensing fibers and flexible optical fiber helical layers (3) are used to monitor the wide area of ​​stress distribution on the surface of the anchor rod body (1); The outer surface of the anchor rod body (1) is coated with a nanocapsule-filled self-repairing coating (4); when microcracks are generated on the surface of the anchor rod body (1) due to stress, the nanocapsules in the nanocapsule-filled self-repairing coating (4) rupture and release a silane repair agent to repair the crack surface.

2. A coal mine roadway roof displacement monitoring device according to claim 1, characterized in that: A screw rod (10) is installed on the top of the anchor rod body (1), and the outer surface of the screw rod (10) is threadedly connected to a main connector (11). The outer surface of the main connector (11) is welded with multiple groups of secondary connectors (12), and the outer surfaces of the main connector (11) and the secondary connector (12) are both embedded with uniformly distributed piezoelectric ceramic sheets (13).

3. The coal mine roadway roof displacement monitoring device according to claim 1, characterized in that: The outer surface of the nanocapsule-filled self-repairing coating (4) is provided with upper and lower sliding sleeves (14), and the surfaces of the two groups of sliding sleeves (14) close to each other are provided with symmetrically arranged storage grooves, and the interiors of the four groups of storage grooves are hinged with connecting rods (15), and one end of the upper and lower groups of connecting rods (15) is hinged with a support plate (16).

4. The coal mine roadway roof displacement monitoring device according to claim 1, characterized in that: The interior of the anchor rod body (1) is equidistantly distributed with FBG arrays (5) along the axial direction, the outer surface of the bottom end of the anchor rod body (1) is provided with a threaded groove (6), the outer surface of the threaded groove (6) is threadedly connected with a fastening nut (7), a monitoring box (8) and a junction box (9) are installed at the bottom of the top plate, and the junction box (9) is located on one side of the monitoring box (8), the monitoring box (8) and the junction box (9) are connected by a cable, and the bottom end of the FBG array (5) extends into the interior of the monitoring box (8).

5. The coal mine roadway roof displacement monitoring device according to claim 1, characterized in that: The spiral pitch of the groove (2) is dynamically adjusted according to the rock properties of the roadway roof, with the pitch being reduced in hard rock sections and expanded in soft rock sections.

6. The coal mine roadway roof displacement monitoring device according to claim 2, characterized in that: The secondary connectors (12) are arranged radially to form a spatial stress gradient sensing network.

7. The coal mine roadway roof displacement monitoring device according to claim 3, characterized in that: The outer surface of the nanocapsule-filled self-repairing coating (4) is provided with baffles arranged up and down, and the top of the lower baffle is in contact with the bottom of the lower sliding sleeve (14), and the upper baffle is located between the two sets of sliding sleeves (14). In a free state, the upper sliding sleeve (14) can slide downward and push the support plate (16) to expand outward under the action of the connecting rod (15).

8. The coal mine roadway roof displacement monitoring device according to claim 4, characterized in that: The monitoring box (8) is provided with a data acquisition device and a data processing device inside. The data acquisition device is used to collect multivariate parameters, and the data processing device is used to perform correlation analysis on the collected data, and transmit the processed data and the analysis results to an edge server arranged in an explosion-proof chamber at the entrance of the tunnel through a LoRa gateway.

9. The coal mine roadway roof displacement monitoring device according to claim 8, characterized in that: The edge server deploys the ST-CGN algorithm to perform four-dimensional evolution analysis of roof displacement changes.

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