A tunnel roof separation monitoring device and monitoring method based on optical sensing technology

Abstract

The present invention discloses a tunnel roof delamination monitoring device and monitoring method based on optical sensing technology, comprising a bottom shell, an upper cover, and an anchor rod tube fixedly mounted on the outer wall of the upper cover; the upper cover is detachably mounted on the top of the bottom shell via a fixing seat and anti-loosening bolts; a mounting seat with a hexagonal slot is integrally formed in the center of the bottom shell; a hollow aluminum alloy connecting bar is sleeved on the mounting seat through an interference fit; a flange is welded at the end of the connecting bar, and positioning holes are evenly distributed on the surface of the flange for fixing four sets of light strip discs equidistantly around the outer wall of the connecting bar; a light strip is wound inside the light strip disc. The present invention can achieve high-precision, real-time dynamic monitoring of the tunnel roof delamination, effectively resist interference from complex underground environments, and at the same time, through intelligent early warning functions, significantly improve the safety monitoring level of mine tunnel roofs, reduce the risk of safety accidents, and provide reliable protection for mine safety production.

Description

Technical Field

[0001] The present invention relates to the technical field of mine safety monitoring, and in particular to a tunnel roof separation monitoring device and a monitoring method based on optical sensing technology. Background Art

[0002] Traditional tunnel roof separation monitoring technologies mainly include mechanical displacement meters, resistance strain gauge monitoring, and early fiber grating sensors.

[0003] Mechanical displacement meters rely on manual readings, have a low monitoring frequency, and an accuracy of only 1mm. They are unable to adapt to the harsh environment of high dust and humidity underground, and are prone to mechanical component jamming. Although resistance strain gauge monitoring can achieve a certain degree of automation, the strain gauge is easily affected by temperature drift, and the vibration environment underground can cause the strain gauge solder joints to fall off, resulting in poor data reliability.

[0004] With the development of sensing technology, fiber Bragg grating sensors have begun to be used in roof monitoring. They use the wavelength encoding principle to measure displacement with a theoretical accuracy of up to 0.01mm. However, there are the following technical bottlenecks:

[0005] The fiber optic fusion splicing process is complex and difficult to maintain on-site underground. A single fusion splicing takes about 30 minutes and is sensitive to the anchor installation angle. When the rock formation inclination exceeds 15°, the strain transmission efficiency of the fiber optic sensor drops by more than 20%. The cost is high, and the price of a single set of monitoring equipment is too high, making it difficult to promote on a large scale.

[0006] In addition, the complex underground environment poses severe challenges to the reliability of monitoring equipment: the dust concentration is high, traditional optical components are easily contaminated, resulting in signal attenuation; the humidity is high, electronic components are easily affected by moisture and fail, and there is electromagnetic interference, which affects the stability of signal transmission.

[0007] The average trouble-free operation time of existing optical sensing monitoring devices in the above environment is less than 6 months, which cannot meet the needs of long-term continuous monitoring in mines.

[0008] Therefore, how to provide a tunnel roof separation monitoring device and monitoring method based on optical sensing technology is a problem that technical personnel in this field urgently need to solve. Summary of the Invention

[0009] One purpose of the present invention is to propose a tunnel roof separation monitoring device and monitoring method based on optical sensing technology. The present invention can realize high-precision, real-time dynamic monitoring of the tunnel roof separation, effectively resist the interference of complex underground environment, and at the same time, through the intelligent early warning function, significantly improve the safety monitoring level of mine tunnel roof, reduce the risk of safety accidents, and provide reliable protection for mine safety production.

[0010] According to an embodiment of the present invention, a tunnel roof separation monitoring device based on optical sensing technology includes a bottom shell, an upper cover, and an anchor rod tube fixedly installed on the outer wall of the upper cover;

[0011] The top of the bottom shell is detachably mounted with an upper cover through a fixing seat and anti-loosening bolts. A mounting seat with a hexagonal slot is integrally formed in the center of the bottom shell. A hollow aluminum alloy connecting strip is sleeved on the mounting seat through an interference fit. A flange is welded to the end of the connecting strip. Positioning holes are evenly distributed on the surface of the flange for fixing four sets of light strips at equal distances around the outer wall of the connecting strip.

[0012] A light strip is wound inside the light strip reel, and four groups of ambient light sensors are distributed in a ring-shaped pattern at 90° intervals with the mounting seat as the center on the inner wall of the bottom shell. The center of the probe of each group of ambient light sensors is at the same height as the axis of the light strip reel and faces the light-emitting surface of the light strip.

[0013] An anchor tube is fixedly installed in the center of the outer side of the upper cover, and an anchor disc for dispersing radial loads is sleeved on the outer wall of the anchor tube. An inverted cone-shaped anchor head is fixedly installed on the other end of the anchor tube. The ends of the four groups of light strips away from the light strip disc are fixedly connected to steel wire ropes through copper crimping terminals. The steel wire ropes pass through the anchor tube and the anchor head, and an adjustable angle anchor claw is fixedly installed on the end.

[0014] The outer wall of the light strip disk is provided with a spring seat, and the spring seat has a built-in spring. The spring is used to provide a constant tension of 6±0.3N for the light strip to ensure the position detection accuracy when the light strip moves with the wire rope. The spring tension calculation formula is:

[0015] Spring torque ,in is the spring rotation angle, which is converted into linear tension T=M / r, where r is the radius of the light strip reel, so T=( ) / r, which ensures =0.75rad, T=6N, meeting the constant tension requirement of 6±0.3N to prevent the light strip from loosening or over-stretching.

[0016] Furthermore, an aviation plug is embedded on the top of the bottom shell, and the aviation plug integrates a two-core 24V power cable and a four-core shielded signal cable to realize power supply and data transmission between the light strip and ambient light sensor and the external power supply and signal processing module;

[0017] The ambient light sensor, model APDS-9960, integrates a 525nm bandpass filter and a 20dB gain amplifier circuit on the front end. The bandpass filter has a half-bandwidth of ≤10nm and an amplifier noise density of ≤1nV / √Hz, enabling the sensor to detect the light source's position with a resolution of 0.03mm. Underground lighting sources typically use 400-500nm blue light and 600-700nm red light. 525nm falls in the middle wavelength range, effectively filtering out ambient light interference. The 20dB gain amplifier amplifies weak light signals to a detectable range, and combined with an amplifier with a noise density of ≤1nV / √Hz, ensures a signal-to-noise ratio of ≥30dB.

[0018] Furthermore, the butt joint edges of the bottom shell and the upper cover are integrally formed with an annular fixing seat, which is connected by four sets of anti-loosening bolts. The anti-loosening bolts adopt a double nut insert structure and are coated with thread locking agent, and are combined with a silicone rubber sealing ring with a cross-sectional diameter of 3mm to form an IP66-level dustproof and waterproof sealing structure. The sealing structure has been tested with a positive pressure of 1.5kPa, and the pressure decay within two hours is ≤5%.

[0019] Furthermore, the anchor claw adopts an X-shaped four-claw structure, and the end of each claw is provided with a locking mechanism consisting of an articulated joint and a locking bolt, which can be adjusted within a range of ±15°, adapting to the anchoring requirements of rock formation inclinations of 0° to 30°;

[0020] The surface of the anchor claw body is welded with tungsten carbide alloy teeth, and the pull-out resistance in sandstone formations is ≥55kN. The hardness of the tungsten carbide alloy teeth is ≥HV1500, and the teeth are evenly distributed at a spacing of 2mm to enhance the rock formation bite ability.

[0021] When the anchor claw angle is adjusted to 15° and the tooth spacing is 2mm, the contact stress with the sandstone hole wall is evenly distributed, the maximum stress is 120MPa, and the simulated pull-out force value is 58kN.

[0022] Furthermore, the steel wire rope is coated with a 0.3mm thick polytetrafluoroethylene wear-resistant coating, has a diameter of 0.5-1.5mm, and a tensile strength of not less than 2000MPa. The steel wire rope adopts a stainless steel wire stranding structure. The steel wire rope adopts a 19-strand stainless steel wire stranding structure, with 7 0.15mm Φ steel wires per strand, and is coated with a 0.3mm thick polytetrafluoroethylene wear-resistant coating. The diameter is 1.2mm, and the tensile strength is 2300MPa. The elongation at break is ≤1.5%. After 500,000 reciprocating friction tests, the coating thickness decreases by ≤10%.

[0023] Furthermore, the connecting bar is a hollow aluminum alloy rod with a length of 80 mm and an inner wall that is anodized. The flange and the connecting bar are welded by a stir friction welding process, and the tensile strength of the weld is ≥300 MPa, ensuring that the installation coaxiality error of the four sets of light strips is ≤0.1 mm.

[0024] Furthermore, the light strip is 8mm wide, the surface is covered with a temperature-resistant silicone layer, the minimum bending radius is 15mm, the light-emitting surface of the light strip is treated with diffuse reflection, and the light-emitting angle is ≥120°, ensuring that the ambient light sensor can detect the light source position at all angles.

[0025] Furthermore, the hexagonal slot of the mounting seat is interference fit with the connecting bar, and the fitting tolerance is H7 / g6, which prevents the connecting bar from rotating circumferentially. The four groups of ambient light sensors distributed in a ring with 90° intervals around the mounting seat as the center on the inner wall of the bottom shell form an XY plane rectangular coordinate system.

[0026] A monitoring method for a tunnel roof separation monitoring device based on optical sensing technology comprises the following steps:

[0027] S1. Device installation: Use an anchor drill to drill a hole in the roof, insert the anchor claw into the hole and adjust the locking mechanism so that the claw fits the hole wall. After injecting the fast-hardening resin anchoring agent and curing it, insert the connecting strip connected to the light strip disc into the mounting seat of the bottom shell. Fasten the upper cover and tighten the anti-loosening bolts in diagonal order to ensure that the sealing ring is evenly compressed to achieve IP66 sealing.

[0028] The anchor drill rig drills a Φ32mm hole in the roof. The depth is determined according to the monitoring layer. The anchor claw is inserted into the hole, the hinge joint is adjusted to make the claw fit the hole wall, and a fast-hardening resin anchor is injected. The connecting strip connected to the light strip disc is embedded in the hexagonal slot of the bottom shell. The upper cover is buckled and the anti-loosening bolts are tightened in diagonal order to ensure that the sealing ring is evenly compressed.

[0029] S2. Connect the light strip to a 24V DC power supply through the aviation plug and light it up for 5 minutes. The ambient light sensor collects initial light intensity data at a frequency of 100Hz. The center position of the light source is fitted using the least squares method to establish polar coordinate reference data.

[0030] The polar coordinate reference data is established by taking the center of the bottom shell as the origin O(0,0) and using the formula Calculate the initial center coordinates of the light source to eliminate the initial installation deviation, where To detect the coordinates of the sensor in real time, eliminate the initial installation deviation, and establish polar coordinate reference data, n is the number of sampling points, and n ≥ 2000.

[0031] S3. Real-time monitoring of delamination: When the roof rock shifts, the anchor claw drives the wire rope to move, and the light strip is pulled out from the light strip reel or reeled in by the spring. The ambient light sensor captures the light source displacement signal at a frequency of 100Hz and converts it into an electrical signal, which is transmitted to the external PLC via the RS485 bus.

[0032] According to the Lambert-Beer law (k is the light source intensity constant, is the distance from the light source to the sensor), establish an overdetermined set of equations, and solve the real-time coordinates of the light source by the least squares method , separation amount .

[0033] S4, dynamic warning and maintenance: the data processing unit presets three levels of safety thresholds. Reaching yellow warning 5mm≤ When the diameter is less than 10mm, the local sound and light alarm and team SMS notification will be triggered, and the orange warning will be 10mm≤ When the instrument is less than 15mm, voice broadcast and dispatch center data interaction will be activated, and red warning will be issued. When the diameter is ≥15mm, cut off the non-safety power supply in the area and upload the encrypted data to the group monitoring platform. At the same time, regularly check the wear of the wire rope and the locking status of the anchor claw.

[0034] Furthermore, the PLC calculates the separation amount by using a triangulation positioning algorithm combined with a Kalman filter, specifically:

[0035] Establish a mathematical model of the distance from the light source to the sensor and the light intensity based on the Lambert-Beer law , solve the real-time coordinates of the light source by the least squares method , separation amount And the positioning accuracy is improved to 0.05mm level through Kalman filtering.

[0036] The beneficial effects of the present invention are:

[0037] 1. The present invention adopts four groups of ambient light sensors distributed in a 90° ring, and cooperates with the light strip disk structure with an integrated clockwork spring to capture the position changes of the light source of the light strip in real time. Among them, the position changes of the light strip as the wire rope moves under the action of a constant tension of 6±0.3N can be accurately sensed by the sensor. Combined with the triangulation positioning algorithm, the light source position detection accuracy of 0.05mm is achieved, ensuring the effective monitoring of the 0.1mm-level subtle delamination displacement of the roof rock stratum. In addition, with the IP66-level dustproof and waterproof sealing structure, it significantly suppresses the interference of dust, moisture and stray light in the well.

[0038] 2. The monitoring method of the present invention integrates dynamic calibration, real-time calculation and multi-level early warning functions to build a full-process intelligent monitoring system. During the installation phase, polar coordinate reference data is established through the least squares method to eliminate the initial installation deviation. During the monitoring process, the light intensity signal is collected in real time at a sampling frequency of 100Hz and transmitted to the PLC via the RS485 bus for triangulation positioning calculation, realizing the dynamic display of the separation curve at 1 time / second and 365-day historical data tracing. The three-level safety threshold mechanism builds a gradient risk response system. The yellow warning triggers the local sound and light alarm and the team SMS notification. The orange warning is linked to the voice broadcast and the dispatch center data interaction. The red warning directly cuts off the non-safe power supply in the area and encrypts and uploads it to the group monitoring platform, forming a three-dimensional safety protection from local warning to global control. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0040] Figure 1 This is a schematic diagram of the overall structure of a tunnel roof separation monitoring device based on optical sensing technology proposed in the present invention;

[0041] Figure 2 This is a disassembled structural diagram of a tunnel roof separation monitoring device based on optical sensing technology proposed in the present invention;

[0042] Figure 3 This is a diagram showing the connection structure of the light strip and steel wire rope of a tunnel roof separation monitoring device based on optical sensing technology proposed by the present invention;

[0043] Figure 4 This is a flow chart of the method of using a tunnel roof separation monitoring device based on optical sensing technology proposed by the present invention.

[0044] In the figure: 1. Bottom shell; 2. Upper cover; 3. Anchor rod pipe; 4. Anchor pipe grille; 5. Anchor head; 6. Anchor plate; 7. Connecting strip; 8. Spring seat; 9. Light strip plate; 10. Light strip; 11. Navigation plug; 12. Anchor claw; 13. Flange; 14. Ambient light sensor; 15. Wire rope; 16. Fixing seat; 17. Anti-loosening bolt; 18. Mounting seat. DETAILED DESCRIPTION

[0045] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or the orientations or positional relationships in which the inventive product is usually placed when in use. These are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention. In the description of the present invention, it should also be noted that, unless otherwise expressly specified and limited, the terms "setting", "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be a communication between the internal parts of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. In the event of any inconsistency, the meaning described in this specification or the meaning derived from the contents recorded in this specification shall prevail. In addition, the terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0047] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0048] like Figure 1-Figure 3 As shown, a tunnel roof separation monitoring device based on optical sensing technology includes a bottom shell 1, an upper cover 2 and an anchor tube 3;

[0049] The bottom shell 1 is made of high-strength aluminum alloy, and the inner wall is anodized with a thickness of 20μm. The butt edge of the bottom shell 1 and the upper cover 2 is integrally formed with an annular fixing seat 16, and the upper cover 2 and the bottom shell 1 are connected by 4 sets of M8 anti-loosening bolts 17. The bolts adopt a double nut insert structure, and the thread surface is coated with Loctite243 locking agent. It is matched with a silicone rubber sealing ring with a cross-sectional diameter of 3mm to form an IP66-level dustproof and waterproof sealing structure. A cylindrical mounting seat 18 is injection-molded in the center of the bottom shell 1, and a hexagonal slot is opened on the top, which is interference fit with the connecting strip 7 to prevent circumferential rotation.

[0050] The connecting bar 7 is a hollow aluminum alloy rod with a length of 80mm. A circular flange 13 is welded at the end. There are 4 sets of positioning holes evenly distributed on the surface. 4 sets of light strip reels 9 are fixed by M5 bolts. The light strip reels 9 are cylindrical reels with a size of Φ50mm×30mm. The outer wall is equipped with a spring seat 8. The inner wall is integrated with a spring spring to provide a constant tension T=6N ( =0.75rad); one end of the spring is pinned to the inner wall of the spring seat, and the other end is connected to the reel's pivot key, providing a constant tension of 6±0.3N for the light strip 10. The light strip 10 uses a flexible LED light source, is 8mm wide, and is covered with a heat-resistant silicone layer. It has a minimum bend radius of 15mm and can withstand 100,000 tensile fatigue tests when wound on a reel.

[0051] The inner wall of the bottom shell 1 is centered on the mounting base, with four groups of ambient light sensors 14 distributed in a circular pattern at 90° intervals. The center of the bottom shell is taken as the origin O(0,0). One group of sensors is in the positive direction of the X-axis, and the direction of the other group of sensors perpendicular to it is in the positive direction of the Y-axis, thus forming an XY plane rectangular coordinate system, which is used for the subsequent precise calculation of the position coordinates of the light source in the plane. The ambient light sensor 14 has a detection range of 0.01-188000lx, a resolution of 0.01lx, and a response time of ≤15ms. The center of the sensor probe is at the same height as the axis of the light strip disk 9, facing the luminous surface of the light strip 10. The sensor communicates with the external signal processing module via the RS485 bus, with a sampling frequency of 100Hz, and can detect changes in the position of the light source with an accuracy of up to 0.05mm. An M12 waterproof aviation plug is embedded on the side of the bottom shell 1 as the aviation plug 11, which integrates a 2-core 24V power cord and a 4-core shielded signal cable. The plug is equipped with a metal locking nut to ensure reliable connection in the vibration environment underground.

[0052] Among them, the four sets of ambient light sensors 14 are model APDS-9960, which integrate infrared filters, ambient light sensing and proximity detection functions, with a detection range of 0.01-188000lx, a resolution of 0.01lx, and a response time of ≤15ms.

[0053] Specifically, an XY plane rectangular coordinate system is established by four sets of sensors, and the four sets of sensor coordinates are: (50,0), (0,50), (-50,0), (0,-50) (unit: mm), at the same time, with the center of the bottom shell as the origin O(0,0), through the formula (n≥2000) Calculate the initial center coordinates of the light source and establish polar coordinate reference data. This data is used to eliminate the initial installation deviation and provide a reference for subsequent separation monitoring.

[0054] An anchor tube 3 is welded to the center of the top surface of the upper cover 2, with its inner wall hard chrome-plated to reduce friction with the wire rope. A circular anchor disc 6 is sleeved onto the outer wall of the anchor tube, positioned by a shoulder to distribute radial loads during anchoring. An inverted conical anchor head 5 is welded to the end of the anchor tube, providing an interference fit. The internal rope threading hole is equipped with a guide groove to guide the wire rope 15 through smoothly.

[0055] The wire rope 15 is a 1.2mm diameter, 19-strand stainless steel wire rope coated with a 0.3mm wear-resistant polytetrafluoroethylene coating. It has a tensile strength of 2300 MPa and has been tested underground to withstand 500,000 cycles of reciprocating friction without breaking. One end of the wire rope is secured to the light strip 10 via a copper crimp terminal. The other end passes through the anchor head 5 and connects to the anchor claw 12. The anchor claw 12 features an "X"-shaped four-claw structure, each 70mm long, with an articulated joint at the end. It is secured with an M8 locking bolt and can accommodate rock formation inclinations of 0° to 30°. Tungsten carbide alloy teeth are welded to the claw surface, providing a pullout resistance of ≥55kN in sandstone formations.

[0056] Specifically, in soft rock formations, the anchor claw can be adjusted to an angle of 0°, a 1.5mm diameter steel wire rope is used, and the thickness of the anchor plate 6 is increased to 15mm to disperse the load; in hard rock formations, the anchor claw angle can be adjusted to 30°, the tooth spacing is reduced to 1.5mm, and quick-setting cement anchor is injected to increase the initial anchoring force.

[0057] like Figure 4 As shown, the monitoring method of the tunnel roof separation monitoring device based on optical sensing technology is as follows:

[0058] S1. Installation of the device: First, use an anchor drill to construct a Φ32mm hole in the roof. The depth is determined according to the monitoring layer, such as 2m and 4m layered monitoring. Insert the anchor claw 12 into the hole through the anchor tube 3, adjust the hinge joint to make the claw fit the hole wall, inject fast-hardening resin anchoring agent, and the curing time is ≤90s. After the anchor head 5 forms a mechanical bite with the rock formation, embed the connecting strip 7 connected to the light strip disc 9 into the mounting seat 18 of the bottom shell 1, buckle the upper cover 2 and tighten the anti-loosening bolts 17 in diagonal order to ensure that the sealing ring is evenly compressed.

[0059] S2. Calibrate the light strip and sensor: Connect the light strip to a 24V DC power supply through the air plug, light it up for 10 seconds and let it stabilize for 5 minutes. The ambient light sensor collects 2000 initial light intensity data in the XY plane rectangular coordinate system at a frequency of 100Hz. Based on these data, use the formula: , in, and denote the estimated values or means of x and y, respectively. Real-time detection of coordinates for sensors, is the number of sampling points (n=2000). The least square method is used to fit the center position of the light source through this formula, calculate the initial center coordinates of the light source, establish the polar coordinate reference data, and eliminate the initial installation deviation. At this time, the polar coordinate reference data can be calculated based on the light intensity data in the XY plane rectangular coordinate system, which is used to calibrate the monitoring starting point and calculate the zero point offset. 、 ,like or If the deviation exceeds 0.1 mm, the automatic calibration procedure is triggered until the deviation is less than the threshold value. The benchmark data is stored in the external PLC controller as the benchmark for subsequent monitoring.

[0060] S3. Real-time monitoring of delamination: When the roof rock layer undergoes relative displacement, the anchor claw drives the wire rope to be pulled out or retracted by the spring tension, and the light strip 10 moves synchronously with the wire rope. The light source position produces radial displacement relative to the sensor array in the XY plane rectangular coordinate system. The ambient light sensor collects light intensity signals at a frequency of 100Hz and transmits them to the PLC via the RS485 bus. The PLC calculates the light source displacement in the XY plane rectangular coordinate system based on the triangulation positioning algorithm. The specific steps are as follows:

[0061] ①Establish the sensor array coordinate system. The four sets of sensor coordinates are (50,0), (0,50), (-50,0), (0,-50) (unit: mm);

[0062] ②Real-time detection of the light intensity value of each sensor According to the Lambert-Beer law, the light intensity is inversely proportional to the square of the distance, that is, ,in, is the light intensity value detected by the i-th group of sensors, k is the light source intensity constant, is the distance from the light source to the i-th group of sensors.

[0063] ③Light intensity values detected by four sets of sensors , combined with the position of the sensor in the XY plane rectangular coordinate system, construct the equation group:

[0064] Solve the above equations by the least squares method to obtain the real-time coordinates of the light source , and thus calculate the separation After 2000 laboratory calibrations, the algorithm error is ≤0.2mm; and the coordinate calculation and delamination calculation are both based on the XY plane rectangular coordinate system to ensure the accuracy and consistency of the calculation.

[0065] It should be noted that the use of Kalman filtering to reduce the noise of sensor data, combined with sliding window averaging, can further improve the positioning accuracy to 0.05mm level;

[0066] Specifically, the Kalman filter algorithm reduces noise, and the state equation is: in, 、 is the coordinate of the light source in the X and Y directions at time k, and The target at discrete time points At the moment k, that is, the position coordinates of the target in the X-axis and Y-axis directions at the moment before the current moment k, and are the speeds of the target in the X-axis and Y-axis directions, respectively, reflecting the motion state of the target. T represents the sampling period, that is, the time interval between two adjacent discrete time points, and T=0.01s. and is the process noise, which represents the deviation between the actual state and the ideal state in the X-axis direction and the Y-axis direction due to various uncertainties in the system. The mean square error of the process noise is 0.01mm, and the positioning accuracy is 0.05mm.

[0067] ④The data processing unit displays the separation curve of each layer in real time and stores the data in the SQL Server database.

[0068] S4. Dynamic warning and maintenance: The data processing unit compares the safety threshold and determines whether the separation value exceeds the limit based on the separation value data calculated in the XY plane rectangular coordinate system. If the separation value exceeds the limit, the sound and light alarm is triggered and the remote alarm information is pushed. The wear of the wire rope and the locking status of the anchor claw are checked regularly.

[0069] The safety threshold is specifically divided into three levels, which realizes graded risk response:

[0070] Yellow warning (5mm≤ <10mm): The local sound and light alarm is activated, the red warning light flashes, and a text message warning is sent to the team leader through the 4G module. The text message content includes the measuring point location, real-time separation value and timestamp.

[0071] Orange warning (10mm≤ <15mm): In addition to the yellow warning measures, the tunnel voice broadcast system is linked to play the "roof separation warning, please evacuate the work area immediately and check for hidden dangers" in a loop, and at the same time send a ModbusTCP protocol alarm frame to the mine dispatching center. The monitoring software of the dispatching center automatically pops up a warning pop-up window and flashes a prompt.

[0072] Red Alert ( ≥15mm): triggers an emergency stop signal, cuts off the power supply to non-intrinsically safe electrical equipment in the area through the PLC control relay, and pushes encrypted data to the group company's safety monitoring platform via industrial Ethernet. The data includes the three-dimensional coordinates of the measuring point, the delamination change curve, the anchor stress status and other information. The platform automatically generates an emergency plan and notifies the emergency command center.

[0073] Working principle: After the device is drilled in the roof through the anchor drilling rig, the X-shaped four-claw anchor claw 12 is inserted into the hole. The hinged joint at the end of the single claw of the anchor claw 12 can be adjusted to an angle of ±15°. It fits the hole wall through the locking bolt and injects a fast-hardening resin anchoring agent to form a mechanical bite structure. When different rock layers of the roof are relatively displaced, the anchor claw 12 moves with the target rock layer, directly driving the connected wire rope 15 to produce axial tension or contraction movement. When the roof is delaminated, the anchor claw 12 moves with the rock layer, driving the connected wire rope 15 to move, and the wire rope 15 pulls or releases the light strip 10. The spring on the light strip disk 9 provides constant tension for the light strip 10 to ensure that the light strip 10 moves in line with the roof position. The shift is linearly corresponding. At this time, four groups of ambient light sensors 14 arranged with the center as the origin in the bottom shell 1 detect the light intensity emitted by the light strip 10. The position of the light strip 10 changes due to the delamination of the top plate, and the light intensity detected by each sensor also changes accordingly. Then, a group of equations is established based on the Lambert-Beer law and the sensor light intensity data, and the least squares method is used to solve the position coordinates of the light strip 10, and the delamination amount is calculated. The extended Kalman filter algorithm is used to process the data to reduce underground noise interference. Finally, the data processing unit compares the calculated delamination amount with the preset three-level safety threshold. When different thresholds are reached, corresponding sound and light alarms, SMS notifications, voice broadcasts, power cuts and other early warning and control measures are triggered respectively.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A tunnel roof separation monitoring device based on optical sensing technology, characterized in that: It comprises a bottom shell (1), an upper cover (2), and an anchor rod tube (3) fixedly mounted on the outer wall of the upper cover (2); The top of the bottom shell (1) is detachably mounted with an upper cover (2) via a fixing seat (16) and anti-loosening bolts (17); a mounting seat (18) with a hexagonal slot is integrally formed in the center of the bottom shell (1); a hollow aluminum alloy connecting strip (7) is sleeved on the mounting seat (18) through an interference fit; a flange (13) is welded to the end of the connecting strip (7); positioning holes are evenly distributed on the surface of the flange (13) for fixing four sets of light strips (9) at equal distances around the outer wall of the connecting strip (7); A light strip (10) is wound inside the light strip disc (9), and four groups of ambient light sensors (14) are distributed in a ring shape at 90° intervals with the mounting seat (18) as the center on the inner wall of the bottom shell (1), and the center of the probe of each group of the ambient light sensors (14) is at the same height as the axis of the light strip disc (9) and faces the light-emitting surface of the light strip (10); An anchor rod tube (3) is fixedly installed in the center of the outer side of the upper cover (2), an anchor plate (6) for dispersing radial load is sleeved on the outer wall of the anchor rod tube (3), an inverted cone anchor head (5) is fixedly installed at the other end of the anchor rod tube (3), and one end of the four groups of light strips (10) away from the light strip plate (9) is fixedly connected to a steel wire rope (15) through a copper crimping terminal, the steel wire rope (15) passes through the anchor rod tube (3) and the anchor head (5), and an angle-adjustable anchor claw (12) is fixedly installed at the end; The outer wall of the light strip disk (9) is provided with a spring seat (8), and the spring seat (8) has a built-in spring for providing a constant tension of 6±0.3N for the light strip (10), so as to ensure the position detection accuracy of the light strip (10) when it moves with the wire rope (15).

2. The device for monitoring the amount of roof separation in a tunnel based on optical sensing technology according to claim 1, characterized in that: An aviation plug (11) is embedded on the top of the bottom shell (1), and the aviation plug (11) integrates a two-core 24V power line and a four-core shielded signal line, which are used to realize power supply and data transmission between the light strip (10) and the ambient light sensor (14) and the external power supply and signal processing module; The front end of the ambient light sensor (14) is integrated with a 525nm bandpass filter and a 20dB gain amplifier circuit, and the half bandwidth of the bandpass filter is ≤10nm, and the amplifier noise density is ≤1nV / √Hz, so that the sensor's detection resolution of the light source position reaches 0.03mm.

3. The device for monitoring the amount of roof separation in a tunnel based on optical sensing technology according to claim 1, characterized in that: The bottom shell (1) and the upper cover (2) are integrally formed with an annular fixing seat (16) at the butt edge thereof and are connected by four sets of anti-loosening bolts (17). The anti-loosening bolts (17) adopt a double nut insert structure and are coated with thread locking agent. They are matched with a silicone rubber sealing ring with a cross-sectional diameter of 3mm to form an IP66 dustproof and waterproof sealing structure. The sealing structure is subjected to a 1.5kPa positive pressure test, and the pressure decay within two hours is ≤5%.

4. The device for monitoring the amount of roof separation in a tunnel based on optical sensing technology according to claim 1, characterized in that: The anchor claw (12) adopts an X-shaped four-claw structure, and a locking mechanism consisting of an articulated joint and a locking bolt is provided at the end of a single claw. The adjustable angle range is ±15°, which is suitable for anchoring requirements with a rock formation inclination angle of 0° to 30°. The surface of the anchor claw (12) is welded with tungsten carbide alloy teeth, and the pull-out resistance in sandstone formations is ≥55kN. The hardness of the tungsten carbide alloy teeth is ≥HV1500, and the tooth spacing is 2mm and evenly distributed to enhance the rock formation bite ability.

5. The device for monitoring the amount of roof separation in a tunnel based on optical sensing technology according to claim 1, characterized in that: The surface of the steel wire rope (15) is coated with a polytetrafluoroethylene wear-resistant coating with a thickness of 0.3 mm, the diameter is 0.5-1.5 mm, and the tensile strength is not less than 2000 MPa. The steel wire rope (15) adopts a stainless steel wire twisted structure.

6. The device for monitoring the amount of roof separation in a tunnel based on optical sensing technology according to claim 1, characterized in that: The connecting bar (7) is a hollow aluminum alloy rod with a length of 80 mm and an inner wall that is anodized. The flange (13) and the connecting bar (7) are welded by a stir friction welding process, and the tensile strength of the weld is ≥300 MPa, ensuring that the installation coaxiality error of the four sets of light strips (9) is ≤0.1 mm.

7. The device for monitoring the amount of roof separation in a tunnel based on optical sensing technology according to claim 1, characterized in that: The light strip (10) is 8 mm wide, and its surface is covered with a heat-resistant silicone layer, with a minimum bending radius of 15 mm. The light-emitting surface of the light strip (10) is treated with diffuse reflection, and the light-emitting angle is ≥120°, ensuring that the ambient light sensor (14) can detect the light source position at all angles.

8. The device for monitoring the amount of roof separation in a tunnel based on optical sensing technology according to claim 1, characterized in that: The hexagonal slot of the mounting seat (18) is interference-fitted with the connecting strip (7), and the fitting tolerance is H7 / g6, so as to prevent the connecting strip (7) from rotating in the circumferential direction. The inner wall of the bottom shell (1) is provided with four groups of ambient light sensors (14) distributed in a ring at 90° intervals with the mounting seat (18) as the center. The center of the bottom shell is taken as the origin O(0,0), and the direction of one group of sensors is the positive direction of the X axis, and the direction of the other group of sensors perpendicular thereto is the positive direction of the Y axis, thereby forming an XY plane rectangular coordinate system.

9. A monitoring method for a tunnel roof separation monitoring device based on optical sensing technology according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Installation of the device: Drill a hole in the top plate using an anchor drill, insert the anchor claw (12) into the hole and adjust the locking mechanism so that the claw body fits the hole wall. After the fast-hardening resin anchoring agent is injected and cured, embed the connecting strip (7) connected to the light strip disc (9) into the mounting seat (18) of the bottom shell (1), buckle the upper cover (2) and tighten the anti-loosening bolts (17) in diagonal order to ensure that the sealing ring is evenly compressed to achieve IP66 grade sealing; S2. Connect a 24V DC power supply through the aerial plug (11), light up the light strip (10) and stabilize it for 5 minutes. The ambient light sensor (14) collects initial light intensity data at a frequency of 100Hz, fits the center position of the light source based on the least squares method, and establishes polar coordinate reference data. The polar coordinate reference data is established by taking the center of the bottom shell as the origin O(0,0) and using the formula Calculate the initial center coordinates of the light source to eliminate the initial installation deviation, where: is the initial center coordinate of the light source, The sensor detects the coordinates in real time, n is the number of sampling points and n ≥ 2000, and the initial installation deviation is eliminated by the least squares method; S3, real-time monitoring of separation amount: when the top rock layer is displaced, the anchor claw (12) drives the wire rope (15) to move, the light strip (10) is pulled out from the light strip disc (9) or reeled in by the spring, and the ambient light sensor (14) captures the light source displacement signal at a frequency of 100 Hz and converts it into an electrical signal, which is transmitted to the external PLC via the RS485 bus; S4, dynamic warning and maintenance: the data processing unit presets three levels of safety thresholds. Reaching yellow warning 5mm≤ When the diameter is less than 10mm, the local sound and light alarm and team SMS notification will be triggered, and the orange warning will be 10mm≤ When the instrument is less than 15mm, voice broadcast and dispatch center data interaction will be activated, and red warning will be issued. When the diameter is ≥15mm, cut off the non-safe power supply in the area and upload the encrypted data to the group monitoring platform. At the same time, regularly check the wear of the wire rope (15) and the locking status of the anchor claw (12).

10. The monitoring method of a tunnel roof separation monitoring device based on optical sensing technology according to claim 9, characterized in that: The PLC calculates the separation amount by using a triangulation positioning algorithm combined with a Kalman filter, specifically: Establish a mathematical model of the distance from the light source to the sensor and the light intensity based on the Lambert-Beer law ,in, is the light intensity value detected by the i-th group of sensors, k is the light source intensity constant, is the distance from the light source to the sensor, and the real-time coordinates of the light source are solved by the least squares method , separation amount And the positioning accuracy is improved to 0.05mm level through Kalman filtering.

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