Dangerous rock mass fracture dynamic tracking method based on magnetic-visual bimodal fusion

Abstract

The invention discloses a dangerous rock mass fracture dynamic tracking method based on magnetic-visual bimodal fusion. The method comprises the following steps: preparing a magnetic fluid; a magnetic induction monitoring module is arranged on one side of the dangerous rock body; a visual monitoring module is installed on the rock mass opposite to the dangerous rock mass; pouring the magnetic fluid into a crack on one side of the dangerous rock body; and monitoring the dynamic expansion condition of the crack. According to the dangerous rock mass fracture dynamic tracking method based on magnetic-visual bimodal fusion, real-time, lossless and full-dimensional monitoring of the dynamic expansion path of the internal fracture of the dangerous rock mass can be realized.

Description

Technical Field

[0001] The present invention relates to a device for dynamically tracking cracks in dangerous rock masses, in particular to a method for dynamically tracking cracks in dangerous rock masses based on magnetic-visual bimodal fusion. Background Art

[0002] Monitoring the crack propagation of dangerous rock masses is the core link of geological disaster early warning. Traditional methods mainly rely on external observation and internal static sensing technologies, which have many limitations. External observation technologies: Using camera monitoring can only trigger an alarm when obvious deformation of dangerous rock parameters occurs, and it is impossible to capture the early dynamic expansion of internal cracks; using displacement gauges can only record the surface displacement, and key information such as the three-dimensional orientation and branch morphology of cracks cannot be analyzed. Internal static sensing technologies (such as fiber optic sensors and resistance strain gauges) can only detect the strain changes at their installation positions, and it is difficult to track the dynamic expansion path of cracks. Moreover, the cracking of rock masses easily causes sensor damage and cannot adapt to harsh environments such as water seepage and weathering for a long time.

[0003] In recent years, some studies have attempted to improve the internal crack monitoring ability by tracer perfusion. For example: By infiltrating a dye liquid into the cracks and combining ultraviolet imaging to indirectly infer the expansion path, but there are problems such as fast volatilization (>5% / hour) and inability to quantitatively invert; using a conductive particle dispersion liquid to monitor the resistance change, but the particles are prone to sedimentation and block the cracks, resulting in monitoring interruption. In summary, the existing technologies lack the ability to monitor the dynamic expansion path of internal cracks in dangerous rock masses in real time, non-destructively, and in all dimensions, and there is an urgent need for a new device that integrates internal tracer and external deformation analysis. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for dynamically tracking cracks in dangerous rock masses based on magnetic-visual bimodal fusion. By injecting a dynamic fluid containing magnetic powder to the crack tip, combining magnetic induction technology to analyze the internal crack orientation in real time, and synchronously deploying a magnetic induction sensor array and an external camera device, effectively realizing the "internal-external bimodal" data complementarity.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: A method for dynamically tracking cracks in dangerous rock masses based on magnetic-visual bimodal fusion, comprising the following steps: Step 1: Prepare magnetic fluid; Step 2: Arrange a magnetic induction monitoring module on one side of the dangerous rock mass; Step 3: Install a visual monitoring module on the rock mass opposite to the dangerous rock mass; Step 4: Inject the magnetic fluid into the crack on one side of the dangerous rock mass; Step 5: Monitor the dynamic expansion of the crack.

[0006] In Step 1, the magnetic fluid includes a fluid, magnetic powder, and an antioxidant. The fluid contains UN resin and donkey hide gelatin; the magnetic powder uses nano-scale ferromagnetic particles; the antioxidant selects 1% oleic acid; the mass ratio of the fluid, magnetic powder, and antioxidant is 4:3:1.

[0007] In Step 1, during preparation, first, mix the UN resin and donkey hide gelatin in a mass ratio of 8:2, and continuously adjust until the fluid has extremely strong fluidity; then, add an appropriate amount of magnetic powder to the fluid material and add a certain amount of 1% oleic acid, and stir the three together evenly.

[0008] In Step 2, the magnetic induction monitoring module includes multiple sets of fluxgate sensors. The fluxgate sensors are arranged in an array and located on one side of the crack. The fluxgate sensors are electrically connected to the network information processor through shielded wires.

[0009] In Step 2, when arranging the magnetic induction monitoring module, first clean the weathered layer on the surface of the dangerous rock; then, arrange a fluxgate sensor at intervals along the surface of the dangerous rock mass, and the fluxgate sensors cover the side of the dangerous rock mass.

[0010] The back of the fluxgate sensor is pasted on the rock mass surface using pmds special glue.

[0011] In Step 3, the visual monitoring module is a camera. The camera is mounted on a fixed bracket, and the focal length is adjusted to cover the entire surface of the dangerous rock mass.

[0012] In Step 4, when injecting the magnetic fluid, first, clean the weathered layer on the top of the dangerous rock, spray an epoxy resin interface agent to form a flat surface; second, select a grouting port at the crack on the top of the dangerous rock mass and inject the magnetic fluid; the magnetic fluid adopts a self-flowing method and flows to all parts where the crack cracks until the crack is full.

[0013] In Step 5, the spatio-temporal alignment algorithm specifically includes: the magnetic induction monitoring module (2) and the visual monitoring module (4) add accurate timestamps to the data through GPS to ensure the matching of magnetic induction data and visual frames at the same time, and establish a unified three-dimensional coordinate system: taking a certain fixed point on the surface of the dangerous rock mass as the origin, through the three-dimensional coordinates of the fluxgate sensor array and the calibration parameters of the multi-spectral camera, map the two types of data to the same coordinate system, so as to achieve spatio-temporal alignment; through simultaneous monitoring of magnetic-visual dual-modal fusion, obtain the real-time three-dimensional distribution map of cracks and the dynamic expansion curve - calculate the crack expansion rate Combine the three-dimensional model to predict the future development trend of the crack and generate a joint monitoring report based on external visual monitoring.

[0014] The present invention provides a method for dynamically tracking cracks in dangerous rock masses based on magnetic-visual dual-modal fusion, having the following technical effects: 1) This device uses magnetic induction technology to analyze the migration path of magnetic fluids in cracks, and for the first time realizes millisecond-level dynamic monitoring of the expansion direction, branching morphology and depth of cracks inside dangerous rock masses. Compared with traditional technologies that rely on surface deformation, it can monitor the expansion process of internal cracks in real time, thus gaining golden time for disaster prevention and control.

[0015] 2) This device uses the crack extension data obtained by the magnetic induction module and the visual monitoring module (multi-spectral camera) and cross-validation to reduce the false alarm rate to less than 5%.

[0016] 3) The magnetic fluid of this device is a fluid formed by UN resin and donkey-hide gelatin, which has good fluidity; and the magnetic powder (nano-scale ferromagnetic particles) can be effectively anti-oxidized by 1% oleic acid, and maintain long-term fluidity for more than 5 years under -20℃-120℃ working conditions, without the risk of volatilization or solidification.

[0017] 4) The fluxgate sensor array of this device is insensitive to temperature and humidity, and can continue to work in complex environments such as heavy rain and at night, making up for the scene limitations of traditional optical monitoring equipment.

[0018] 5) This device does not need to pre-embed a large number of sensors. Monitoring can be started by drilling and injecting magnetic fluid. The cost of single-point equipment deployment is reduced, which enhances the practicality and convenience of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 It is the overall architecture diagram of the present invention.

[0020] Figure 2 This is a simulation effect diagram of the penetration of magnetic fluid in the cracks in the present invention.

[0021] Figure 3 It is a structural schematic diagram of the magnetic induction monitoring module in the present invention.

[0022] Figure 4 It is a schematic diagram of the structure of the visual monitoring module in the present invention.

[0023] Figure 5 It is a schematic diagram of the three-dimensional model of internal cracks in the dangerous rock mass in the present invention.

[0024] In the figure: magnetic fluid 1, magnetic induction monitoring module 2, energy storage module 3, visual monitoring module 4, network information processor 5, dangerous rock mass 6, crack 7, grouting port 1.1, fluid 1.2, magnetic powder particles 1.3, oleic acid 1.4, fluxgate sensor 2.1, wire 2.2, camera 3.1, awning 3.2, expansion direction a. DETAILED DESCRIPTION

[0025] A dynamic tracking method for cracks in dangerous rock masses based on magnetic-visual bimodal fusion, comprising the following steps: Step 1: Prepare magnetic fluid 1; The magnetic fluid material includes a fluid, magnetic powder, and an antioxidant; the fluid material contains UN resin and donkey-hide gelatin. The fluid material has strong fluidity, and the advantage of strong fluidity is that it flows along the direction of crack expansion and has strong adhesion; the magnetic powder uses nanoscale ferromagnetic particles, and the advantage is that the particle size is tiny and can pass through any narrow rock crevice; the antioxidant is selected as 1% oleic acid, which has good antioxidant performance and is compatible with the fluid material.

[0026] When preparing, first, mix UN resin and donkey-hide gelatin in a mass ratio of 8:2, and continuously adjust until the fluid has extremely strong fluidity before it can be put into use; then, add an appropriate amount of magnetic powder to the fluid material and add a certain amount of 1% oleic acid, and stir the three together evenly.

[0027] Finally, the mass ratio of the fluid material: magnetic powder: oleic acid is 4:3:1.

[0028] Here, the four materials cannot be added and mixed at the beginning. The reasons are as follows: 1. The fluid contains UN resin and donkey-hide gelatin, and UN resin and donkey-hide gelatin need to be mixed separately in a ratio of (8:2) and adjusted to ensure that the fluid has extremely strong fluidity. If magnetic powder and oleic acid are directly added, the high solid content will significantly increase the system viscosity, resulting in a decrease in fluidity and unable to meet the subsequent requirement of perfusion into the details of the crack. 2. Nanoscale ferromagnetic particles (magnetic powder) are prone to aggregation due to van der Waals forces in the viscous mixture, forming clusters. 3. Adding magnetic powder step by step can utilize the already adjusted low-viscosity resin-donkey-hide gelatin matrix and achieve uniform dispersion through stirring, avoiding particle sedimentation or agglomeration. Oleic acid needs to be introduced after the magnetic powder is added. Its functions include: oleic acid molecules adsorb on the surface of the magnetic powder to form a monolayer protective film to prevent oxidation; it is compatible with the resin-donkey-hide gelatin system, and premature addition may interfere with the mixing process of resin and donkey-hide gelatin and affect fluidity.

[0029] Step 2: Arrange the magnetic induction monitoring module 2 As Figure 3 shown, clean the weathered layer on the surface of the dangerous rock, and then arrange a fluxgate sensor every 50 cm along the surface of the dangerous rock mass. Use pmds special glue on the back of the fluxgate sensor to paste it on the rock mass surface. The pdms special glue has strong adhesiveness and can tightly adsorb the highly sensitive fluxgate sensor on the surface of the dangerous rock mass. Multiple fluxgate sensors are electrically connected through shielded wires and finally form an array state. The output signals of multiple fluxgate sensors are connected to a data processing terminal, and the data processing terminal is a network information processor 5.

[0030] The model of fluxgate sensor used is: Lake Shore Cryotronics F71, the advantage is: high accuracy.

[0031] The fluxgate sensor array is arranged on the side of the dangerous rock mass, and the advantage of comprehensive coverage of the cracks is that there are four of them in this application, which can form a spatial coordinate system, making it convenient for us to perform digital processing and time-space alignment of the internal expansion of the cracks. The model of the network information processor 5 is: Ultramicro Alchemy AU1000, which has the advantages of low power consumption and high scalability.

[0032] Step 3: Install the visual monitoring module like Figure 4 As shown in the figure, a self-made fixed bracket is installed on the rock mass opposite the dangerous rock mass. The camera is mounted on the fixed bracket, and the focal length is adjusted to cover the entire surface of the dangerous rock mass. The camera can be a multi-spectral camera, and an infrared camera can also be used when the light is poor. The camera is used to capture the surface image of the dangerous rock mass, and through real-time analysis of the captured image, the crack width, length and other parameters are extracted. Combined with manual comprehensive analysis, the dangerous rock morphology and external crack development are identified, which is convenient for observing the surface crack expansion trend of the dangerous rock mass; at the same time, it can be used to monitor the macroscopic deformation of the dangerous rock.

[0033] Step 4: Infusing magnetic fluid; like Figure 2 As shown, clean the weathered layer on the top of the dangerous rock, spray epoxy resin interface agent (thickness of about 2mm) to form a flat surface; select a grouting port in the crack at the top of the dangerous rock mass, and the grouting port must be located at the top of the dangerous rock mass. The advantage of being located at the top of the dangerous rock mass is that due to the influence of gravity, the magnetic fluid material can flow from top to bottom to the entire crack. The magnetic fluid adopts a self-flowing method, which makes it convenient for the magnetic fluid material to flow to all parts of the crack until the crack is filled.

[0034] Step 5: Monitor crack propagation through magnetic induction monitoring module and visual monitoring module.

[0035] The magnetic induction data and visual data are received through the network information processor, which is used to process the internal and external data of the dangerous rock mass cracks. The joint monitoring report is generated by the time-space alignment algorithm, which can greatly improve the accuracy of the early warning.

[0036] Applied to the present application, the specific process of the spatio-temporal alignment algorithm is as follows: The magnetic induction monitoring module 2 and the visual monitoring module 4 add accurate timestamps to the data through GPS to ensure the matching of magnetic induction data and visual frames at the same time. And a unified three-dimensional coordinate system is established: taking a fixed point on the surface of the dangerous rock mass as the origin, through the layout position (three-dimensional coordinates) of the fluxgate sensor array and the calibration parameters of the multispectral camera, the two types of data are mapped into the same coordinate system, so as to achieve spatio-temporal alignment; through the simultaneous monitoring of the magnetic-vision dual-mode fusion, the obtained real-time three-dimensional distribution map of cracks and the dynamic expansion curve - calculate the crack expansion rate. Combined with the three-dimensional model to predict the future development trend of the cracks and the external visual monitoring to generate a joint monitoring report.

[0037] In addition, an energy storage module 3 is also arranged at the top of the dangerous rock mass. The energy storage module 3 includes a solar panel, an energy storage battery (such as a lithium-ion battery), a DC-DC converter, a direct current (DC) cable, and an energy storage inverter. The solar panel is located at the top of the device; the solar panel is connected to the DC-DC converter by a direct current (DC) cable, and the DC-DC converter is located below the solar panel. The energy storage battery is attached below the DC-DC converter, and the bottom surface is the energy storage inverter.

[0038] The solar panel is fixed at a 30° inclination in the unobstructed area at the top of the rock wall and is connected to the DC-DC converter through a DC cable. The energy storage battery is installed below the DC-DC converter, and the direct current is converted into alternating current (220 V) through the energy storage inverter for the system to use. An aluminum alloy protective cover is installed outside the energy storage module 3 to ensure safety in extreme weather. The energy storage module 3 needs to be configured with a low-power mode. On sunny days, the solar panel directly supplies power, and on cloudy days, it switches to battery power supply, which can be flexibly switched and the usage time can be extended.

[0039] The energy storage module 3 is connected by cables. The cables are fixed on the rock wall through rivets along the rock wall and finally connected to highly sensitive fluxgate sensors; both the fluxgate sensors and the cameras are connected to the network information processor by wires, which is convenient for remotely transmitting the obtained data to the hands of the staff for real-time monitoring.

[0040] The crack expansion situation inside the dangerous rock mass can be determined by the arranged fluxgate sensors + magnetic fluid; the fluxgate sensors are placed at specific positions of the dangerous rock mass to form a three-dimensional coordinate system, and combined with the external shape map obtained by the multispectral camera, a three-dimensional space model can be constructed, specifically as Figure 5 shown. The fluid flowing into the crack will show the general direction of crack expansion through the coordinates in the three-dimensional space; the position of the magnetic fluid inside the dangerous rock mass will be displayed through the three-dimensional coordinates. The magnetic fluid will flow along the direction of crack expansion and be remotely displayed on the visual monitoring module, so as to achieve the effect of real-time dynamic display of crack expansion.

[0041] Example 1 Taking a certain granite dangerous rock mass (height 35m, initial crack depth 2.5m, slope 65°) as an example, a perfusion hole is drilled at the top crack, and a magnetic fluid material (containing 12% nano ferromagnetic particles and 1% oleic acid) is injected. The magnetic fluid gradually penetrates into the crack interior; at the same time, 4 fluxgate sensors (for spatial positioning) are arranged along the surface of the dangerous rock mass and firmly fixed with pdms glue; a multi-spectral camera (resolution 4K, spectral range 400 - 1600nm) is synchronously installed with the focal length covering the entire surface of the dangerous rock mass. The magnetic induction module will detect the extension and expansion of the crack, and the crack will expand to penetrate within a certain period of time; at the same time, relevant management personnel observe the surface crack captured by the visual module, and use dual internal and external analysis to judge the danger level of this dangerous rock mass, and corresponding measures can be taken accordingly to prevent the dangerous rock mass from causing certain damage to the safety of people's lives and property. This not only discovers the danger in advance compared with traditional monitoring, buys critical time for personnel evacuation, but also greatly improves the accuracy of risk prevention.

[0042] Example 2 Taking a certain railway tunnel along the Yangtze River as an example, we adapt measures to local conditions and modify the materials in the device to use water-based magnetic fluid (containing 8% iron oxide nanoparticles and 0.5% EDTA antioxidant) to adapt to the humid environment; still, it is injected into the lining crack through a grouting pipe, and the magnetic fluid maintains stable diffusion under water seepage conditions. The magnetic induction sensor array is embedded on the surface of the tunnel lining and encapsulated with waterproof PDMS glue; due to the influence of low light interference in the tunnel, an infrared camera is deployed for the visual module. Through the magnetic induction module, the crack rate of expansion can be obtained, and it can be inferred how long it will take for this tunnel to have safety problems. The speculation process is as follows: through the coordinates in the three-dimensional model, we can obtain the instantaneous rate of the fluid material, and then we can roughly get an approximate time for the crack of this dangerous rock mass to penetrate. We set a safe time point. As long as the crack penetration time of the dangerous rock mass reaches a certain specified time, we need to notify relevant units to pay attention. Thus, early reinforcement or remedial measures can be carried out; compared with the traditional scheme, not only the cost is reduced, but also the tunnel structure does not need to be damaged, and monitoring can be carried out normally in this humid and airtight environment of the tunnel.

Claims

1. A dynamic tracking method for cracks in dangerous rock masses based on magnetic-visual bimodal fusion, comprising the following steps: Step 1: Prepare magnetic fluid; Step 2: Arrange a magnetic induction monitoring module on one side of the dangerous rock mass; Step 3: Install a visual monitoring module on the rock mass opposite the dangerous rock mass; Step 4: Inject the magnetic fluid into the cracks on one side of the dangerous rock mass; Step 5: Monitor the dynamic expansion of the cracks.

2. The dynamic tracking method for cracks in dangerous rock masses based on magnetic-visual bimodal fusion according to claim 1, characterized in that: In Step 1, the magnetic fluid includes a fluid, magnetic powder, and an antioxidant. The fluid contains UN resin and donkey-hide gelatin; the magnetic powder uses nano-scale ferromagnetic particles; the antioxidant is 1% oleic acid; the mass ratio of the fluid, magnetic powder, and antioxidant is 4:3:

1.

3. A dynamic tracking method for cracks in dangerous rock masses based on magnetic-visual bimodal fusion according to claim 2, characterized in that: In Step 1, when preparing, first, mix the UN resin and donkey-hide gelatin in a mass ratio of 8:2, and continuously adjust until the fluid has extremely strong fluidity; then, add an appropriate amount of magnetic powder to the fluid material, and add a certain amount of 1% oleic acid, and stir the three evenly together.

4. A dynamic tracking method for cracks in dangerous rock masses based on magnetic-visual bimodal fusion according to claim 3, characterized in that: In Step 2, the magnetic induction monitoring module includes multiple sets of fluxgate sensors. The fluxgate sensor array is arranged and located on one side of the crack. The fluxgate sensors are electrically connected to the network information processor through shielded wires.

5. A dynamic tracking method for cracks in dangerous rock masses based on magnetic-visual bimodal fusion according to claim 4, characterized in that: In Step 2, when arranging the magnetic induction monitoring module, first clean the weathered layer on the surface of the dangerous rock; then, arrange a fluxgate sensor at intervals along the surface of the dangerous rock mass, and the fluxgate sensors cover the side surface of the dangerous rock mass.

6. A dynamic tracking method for cracks in dangerous rock masses based on magnetic-visual bimodal fusion according to claim 5, characterized in that: The back of the fluxgate sensor is pasted on the rock surface with pmds special glue.

7. A method for dynamically tracking cracks in dangerous rock masses based on magnetic-visual bimodal fusion according to claim 4, characterized in that: In Step 3, the visual monitoring module is a camera. The camera is mounted on a fixed bracket, and the focal length is adjusted to cover the entire surface of the dangerous rock mass.

8. A method for dynamically tracking cracks in dangerous rock masses based on magnetic-visual bimodal fusion according to claim 7, characterized in that: In Step 4, when injecting the magnetic fluid, first, clean the weathered layer on the top of the dangerous rock, and spray an epoxy resin interface agent to form a flat surface; secondly, select a grouting port at the crack on the top of the dangerous rock mass and inject the magnetic fluid; the magnetic fluid adopts a self-flowing method and flows to all parts where the crack cracks until the crack is full.

9. A method for dynamically tracking fractures of dangerous rock masses based on magnetic-visual bimodal fusion according to claim 8, characterized in that: In Step 5, the network information processor receives the magnetic induction data and visual data, and generates a joint monitoring report through a spatio-temporal alignment algorithm.

10. A method for dynamically tracking fractures of dangerous rock masses based on magnetic-visual bimodal fusion according to claim 9, characterized in that: The spatio-temporal alignment algorithm specifically includes: the magnetic induction monitoring module (2) and the visual monitoring module (4) add accurate timestamps to the data through GPS to ensure the matching of magnetic induction data and visual frames at the same time. Moreover, a unified three-dimensional coordinate system is established: taking a certain fixed point on the surface of the dangerous rock mass as the origin, through the layout of the three-dimensional coordinates of the fluxgate sensor array and the calibration parameters of the multispectral camera, the two types of data are mapped into the same coordinate system, so as to achieve spatio-temporal alignment; through the simultaneous monitoring of the magnetic-vision dual modality, the real-time three-dimensional distribution map of cracks and the dynamic expansion curve are obtained - calculate the crack expansion rate Combined with the three-dimensional model to predict the future development trend of cracks and external visual monitoring to generate a joint monitoring report.

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