Coal mine tunnel deformation monitoring sensor based on fiber bragg grating

Abstract

The utility model discloses a coal mine tunnel deformation monitoring sensor based on a fiber bragg grating. The fiber bragg grating sensor comprises a polyvinyl chloride tube and a bare fiber bragg grating, the polyvinyl chloride tube is located at a hollow part in the bare fiber bragg grating, end fixing blocks are fixedly arranged at two ends of the polyvinyl chloride tube, and an optical signal converter and a fiber bragg fiber gyroscope are fixedly arranged in the polyvinyl chloride tube and on the outer wall of the polyvinyl chloride tube respectively. According to the utility model, the polyvinyl chloride pipe provided with the bare fiber grating is fixed in the groove on the roadway pavement through the end part fixing block and the horizontal fixing base, and then the groove is poured and backfilled by using concrete, so that the polyvinyl chloride pipe can be driven to bend through the deformation of the pavement; the deformation is recorded and the wavelength change of the bare fiber bragg grating is measured through the fiber bragg fiber gyroscope, the deformation condition of the roadbed can be accurately measured, compared with a traditional monitoring mode, the monitoring mode is more hidden and is not prone to external interference, and meanwhile the pavement deformation condition can be stably monitored for a long time.

Description

Technical Field

[0001] The utility model belongs to the field of tunnel equipment, in particular to a deformation monitoring inclination sensor, and relates to a coal mine tunnel deformation monitoring sensor based on a fiber Bragg grating. Background Art

[0002] Coal mine pavement is a key transportation facility in underground coal mines, and its safety and reliability are crucial to mine production and the safety of workers. However, due to the particularity of the coal mine environment, the pavement is easily deformed by various factors, such as geological structure, mining activities, hydrological conditions, etc., which may lead to pavement damage, collapse, cracks and other problems, thus affecting the normal operation of the coal mine. Therefore, it is particularly important to monitor the deformation of the coal mine roadside in real time to ensure the normal use of the tunnel.

[0003] Since coal mine tunnels are located deep underground, they are usually affected by geothermal heat, resulting in high temperatures. In addition, water vapor in groundwater and ore layers will also cause high humidity in the tunnels, forming a high-temperature and high-humidity working environment with humidity ranging from 60% to 90%. In addition, transportation vehicles in underground coal mines usually frequently travel between underground working surfaces and the ground, and the road surface needs to frequently withstand heavy loads and high rolling pressures. Therefore, monitoring of vertical deformation is particularly important. However, traditional monitoring methods have problems such as low efficiency and frequency and limited monitoring range. Existing high-precision monitoring technologies have limitations in closed environments such as coal mine tunnels. Therefore, there is an urgent need for a device for monitoring coal mine road surface deformation to fill this gap.

[0004] Coal mining and transportation in the tunnel requires a large amount of mechanical equipment operation, which requires the inclination sensor to withstand huge deformation together with the tunnel structure. At the same time, the precise stress field measurement requires the inclination sensor to have an accuracy of up to dozens or even several micro-strains, which is difficult to achieve with general inclination sensors. In addition, during the coal mining process, the vibration and heavy pressure generated affect the stability of the tunnel structure and equipment. Acidic substances, salt water or other chemicals that may exist in the coal mine tunnel may corrode and erode the tunnel structure and detection equipment, accelerating the aging and damage of the equipment. This means that the inclination sensor must have sufficient rigidity to protect its internal sensitive components. However, after the road surface is formed, the flexible characteristics of the road surface require that the rigidity of the inclination sensor should not be too large so that it can deform in coordination with the road surface. These contradictory requirements for high precision, large range, and both rigidity and flexibility make it difficult for existing inclination sensors on the market to meet the needs. In addition, the material unevenness and large scale of the coal mine road surface also require that the cost of the inclination sensor should not be too high to meet the needs of multiple monitoring points.

[0005] In view of this, the present utility model is proposed. Utility Model Content

[0006] The technical problem to be solved by the utility model is to overcome the deficiencies of the prior art and provide a coal mine tunnel deformation monitoring sensor based on fiber Bragg grating, which solves the problems raised in the above background technology.

[0007] In order to solve the above technical problems, the basic concept of the technical solution adopted by the utility model is:

[0008] A coal mine tunnel deformation monitoring sensor based on fiber Bragg grating comprises: a polyvinyl chloride tube and a bare fiber Bragg grating, the polyvinyl chloride tube is located in the hollow part inside the bare fiber Bragg grating, both ends of the polyvinyl chloride tube are fixedly installed with end fixing blocks, the inner and outer walls of the polyvinyl chloride tube are respectively fixedly installed with an optical signal converter and a fiber Bragg fiber gyroscope, the outer sleeve of the polyvinyl chloride tube is provided with a horizontal fixing base, the horizontal fixing base is provided with a slot, and an inclination sensor is installed in the slot.

[0009] Optionally, a through hole for the optical fiber to extend is formed through the center of the opposite side of the fixing block.

[0010] Optionally, the outer surface of the polyvinyl chloride tube is coated with silicone rubber, and the silicone rubber forms a coating after drying.

[0011] Optionally, a plurality of holes are formed through the opposite sides of the end fixing block, the side walls of each hole are provided with an internal thread, a limiting nail is passed through the hole, and a thread groove corresponding to the hole is formed on the side of the polyvinyl chloride tube facing the end fixing block.

[0012] Optionally, an external thread is formed on an outer side wall of the limiting pin, and the external thread of the limiting pin is threadably connected to the internal thread and passes through a hole and a thread groove to establish a connection.

[0013] Optionally, extension grooves are provided on both sides of the card slot, and two extension blocks located in the extension grooves are fixed on both sides of the inclination sensor by glue, and the extension blocks are fixed inside the extension grooves by bolts.

[0014] Optionally, the number of the holes is four, and the number of the limiting pins is two.

[0015] Optionally, the horizontal fixing base is made of metal material or fiber reinforced plastic, and the end fixing block is made of epoxy resin material or metal material.

[0016] Optionally, a plurality of the optical signal converters are evenly arranged in a straight line on the inner wall of the polyvinyl chloride tube, and the optical signal converters are evenly distributed on the optical fiber at intervals of 50 cm.

[0017] Optionally, an arc-shaped structure is fixedly connected to the top of the horizontal fixed base, and the polyvinyl chloride tube is located in a hollow portion of the arc-shaped structure.

[0018] After adopting the above technical solution, the utility model has the following beneficial effects compared with the prior art. Of course, any product implementing the utility model does not necessarily need to achieve all the advantages described below at the same time:

[0019] 1. By embedding the sensor directly into the road surface, the deformation and other characteristics of the road surface can be monitored more accurately, and the high rolling pressure of heavy-loaded vehicles will not damage the sensor, thereby extending the service life of the sensor.

[0020] 2. Due to the accuracy of the grating optical fiber itself, it is close to absolute measurement. The design of implantable sensor tube is adopted. By embedding the bare fiber grating in the polyvinyl chloride pipe and sticking it on both sides of the road surface, sensitive monitoring of tunnel deformation is achieved and the monitoring accuracy is improved. Compared with traditional monitoring methods, this design is more concealed and less susceptible to external interference. At the same time, it can monitor the deformation of the roadbed in a long-term and stable manner. Sensors based on bare fiber grating have the advantages of high sensitivity, light weight, corrosion resistance, low optical loss and anti-electromagnetic interference, as well as real-time and remote monitoring capabilities.

[0021] 3. Use larger diameter polyvinyl chloride pipes with good toughness, heat resistance and ductility as the base material, which is easy to deform with the tunnel structure and has little effect on the strain field of the tunnel structure itself.

[0022] 4. The sensor can not only measure the vertical deformation of a single point, but also measure the vertical deformation of a continuous area. The horizontal fixed base can also play a certain role in overall deformation and is not affected by the sudden strain change caused by material unevenness at a single point. At the same time, the inclination sensor on the horizontal fixed base can synchronously monitor the bending deformation of the road surface.

[0023] The specific implementation of the utility model is further described in detail below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described below are only some embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0025] In the figure:

[0026] Figure 1 It is a schematic diagram of the top view structure of the utility model;

[0027] Figure 2 It is a right view structural schematic diagram of the utility model;

[0028] Figure 3 This is a schematic diagram of the split structure of the utility model;

[0029] Figure 4 This is a front view structural schematic diagram of the utility model;

[0030] Figure 5 It is a schematic diagram of the cross-sectional structure of the utility model;

[0031] Figure 6 for Figure 4 A schematic diagram of the enlarged structure in the middle.

[0032] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0033] Polyvinyl chloride tube 1, bare fiber Bragg grating 2, hole 3;

[0034] End fixing block 4, internal thread 401;

[0035] Optical signal converter 5, fiber Bragg fiber gyroscope 6, horizontal fixing base 7, card slot 8, tilt sensor 9, silicone rubber 10;

[0036] Limiting nail 11, external thread 1101;

[0037] Extension block 12.

[0038] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but rather to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0039] The utility model will now be further described in detail with reference to the accompanying drawings.

[0040] See also Figure 1-6As shown, in this embodiment, a coal mine tunnel deformation monitoring sensor based on fiber Bragg grating is provided, including a polyvinyl chloride tube 1 and a bare fiber Bragg grating 2. The polyvinyl chloride tube 1 and the bare fiber Bragg grating 2, the polyvinyl chloride tube 1 is provided with a groove 3, the bare fiber Bragg grating 2 is clamped in the groove 3, the two ends of the polyvinyl chloride tube 1 are fixedly installed with end fixing blocks 4, and the central position of the opposite side of the fixing block 4 is penetrated with a through hole for the optical fiber to extend. The inner and outer walls of the polyvinyl chloride tube 1 are respectively fixedly installed with an optical signal converter 5 and a fiber Bragg fiber gyroscope 6, the outer sleeve of the polyvinyl chloride tube 1 is provided with a horizontal fixing base 7, the horizontal fixing base 7 is provided with a slot 8, and the slot 8 is provided with an inclination sensor 9, the outer surface of the polyvinyl chloride tube 1 is coated with silicone rubber 10, and the silicone rubber 10 forms a coating after drying, the side walls of the multiple holes 3 of the end fixing block 4 are provided with internal threads 401, and the multiple holes 3 of the end fixing block 4 are penetrated with a limit nail 11, and the outer side of the limit nail 11 The wall is provided with an external thread 1101, and the external thread 1101 of the limiting nail 11 is threadedly connected with the internal thread 401, and is connected through the hole 3 and the thread groove. The setting of the thread groove can make a connection relationship between the fixing block 4 and the polyvinyl chloride tube 1. A plurality of optical signal converters 5 are evenly installed on the inner wall of the polyvinyl chloride tube 1 in a straight line, and the optical signal converters 5 are evenly distributed on the optical fiber at intervals of 50 cm. An arc-shaped structure is fixedly connected above the horizontal fixed base 7, and the polyvinyl chloride tube 1 is located in the hollow part of the arc-shaped structure. The number of the holes 3 is four, and the number of the limiting nails 11 is two. By leaving two holes 3 without the limiting nails 11, it can play a positioning role in the subsequent process of splicing the polyvinyl chloride tube 1.

[0041] A through hole for the optical fiber to extend is provided through the center of the opposite side of the fixing block 4. The provision of the through hole facilitates the subsequent extension of the optical fiber.

[0042] The application of one aspect of this embodiment is as follows: a plurality of optical signal converters 5 are arranged according to the length of the polyvinyl chloride tube 1, and the optical signal converters 5 are evenly distributed on the polyvinyl chloride tube 1 at intervals of 50 cm. The fiber Bragg fiber gyroscope 6 can accurately determine the orientation of the moving object. Each sensor is tested simultaneously by a plurality of bare fiber gratings 2, and the plurality of bare fiber gratings 2 are equidistantly arranged in the groove 3 of the polyvinyl chloride tube 1 at a distance of 50 cm. The plurality of bare fiber gratings 2 simultaneously monitor environmental changes to improve the sensitivity and accuracy of the sensor, thereby obtaining more reliable data. The central reflection wavelength of each bare fiber grating 2 is different, and is arranged in ascending order relative to the end fixing block 4, and is passed through the middle of the lane. A groove is excavated on the ground, the surface of the polyvinyl chloride pipe 1 is roughened with a planer to make it fit perfectly with the surrounding concrete and deform together under the load, and an adhesive that cures quickly at room temperature is filled in the groove 3 to make the bare fiber grating 2 completely embedded in the groove 3, and the polyvinyl chloride pipe 1 with the bare fiber grating 2 in the groove 3 is placed in the groove, and the end fixing blocks 4 are placed at both ends of the groove, and an arc structure is fixedly installed on each horizontal fixed base 7, and the polyvinyl chloride pipe 1 is inserted between the closed loop structure surrounded by the horizontal fixed base 7 and the arc structure. A plurality of equidistantly arranged horizontal fixed bases 7 are provided on the polyvinyl chloride pipe 1, and each horizontal fixed base 7 is fixed on the ground.

[0043] By rotating the limit pin 11, the external thread 1101 is driven to rotate, and the external thread 1101 is threadedly connected with the internal thread 401. When the external thread 1101 rotates, it drives the limit pin 11 to move away from the end fixing block 4, so that the limit pin 11 can be inserted into the groove to increase the stability of the end fixing block 4. Then, silicone rubber 10 is coated on the surface of the polyvinyl chloride tube 1 to extend the service life of the implanted sensor and protect the polyvinyl chloride tube 1 from damage due to contact with the surrounding concrete while maintaining appropriate elasticity. The FC / APC connector is welded to one end of the bare fiber grating 2 using a fiber fusion splicer, and the connector is connected to the optical interrogator during testing. Then, concrete is poured into the groove, so that the sensor can be tightly combined with the surrounding concrete.

[0044] When a car rolls over the road surface, the deformation of the road surface drives the polyvinyl chloride tube 1 to deform. After the deformation of the polyvinyl chloride tube 1, the bare fiber Bragg grating 2 is deformed and the horizontal fixed base 7 moves. The optical signal converter 5, the fiber Bragg fiber gyroscope 6 and the tilt sensor 9 are all driven to measure the strain of the bare fiber Bragg grating 2 to obtain an initial reference value in order to understand the initial shape of the bottom of the measured road surface layer where the sensor is located. Then, the theory of continuous medium mechanics and elastic mechanics is used for calculation: According to the theory of continuous medium mechanics and elastic mechanics, the lateral displacement of the beam can be calculated. In the calculation, it is assumed that the material has linear strain and there is a linear geometric relationship between the small displacement and the strain. According to the bending theory, the bending strain of the road surface can be calculated. The bending strain is related to the radius of curvature and the distance from the neutral plane. In the vertical strain field test of the tunnel structure, an optical signal converter 5 is used to measure the deformation of the tunnel structure layer. By applying dynamic and static loads, the polyvinyl chloride tube 1 is close to the tunnel structure layer and bends accordingly. The strain response of each bare fiber grating 2 is measured in real time. The strain data of the bare fiber grating 2 is converted into a continuous strain curve using methods such as polynomial fitting, and then the vertical deformation of the bottom of the tunnel structure layer is determined. The test accuracy depends on the number, density and test range of the bare fiber grating 2. The direction control seat with very small deformation is used as the reference point. Each measured curve is compared with the curve of the initial state to obtain a continuous vertical deformation curve of the tunnel structure layer. Through long-term data collection, this method can monitor the permanent deformation of the pavement structure and provide a reliable assessment of the state of the tunnel structure. It should be noted that all electrical equipment involved in this application can be powered by batteries or external power supplies.

[0045] like Figure 3 As shown, in this embodiment, both sides of the card slot 8 are provided with extension grooves, and two extension blocks 12 located in the extension grooves are fixed on both sides of the inclination sensor 9 by glue, and the extension blocks 12 are fixed inside the extension grooves by bolts. Further, the use of the extension blocks 12 can be eliminated in this application, and the inclination sensor 9 can be fixed directly with quick-drying glue.

[0046] like Figure 1-4 As shown, the end fixing block 4 of this embodiment is made of epoxy resin material or metal material, and the horizontal fixing base 7 is made of metal material or fiber reinforced plastic.

[0047] In this embodiment, the epoxy resin material has the advantages of strong adhesion, good chemical resistance, small shrinkage force, good electrical insulation, good stability, high mechanical properties, good heat resistance and environmental safety. The fiber reinforced material has the advantages of good heat resistance, strong impact resistance, good rigidity, good flame retardancy, good durability, corrosion resistance and good vibration resistance. The metal material has the advantages of high strength, high toughness, corrosion resistance and wear resistance. Suitable materials can be selected according to geological needs.

[0048] The present invention is not limited to the above-mentioned implementation modes. Anyone should be aware of the structural changes made under the inspiration of the present invention. Any technical solution that is the same or similar to the present invention falls within the protection scope of the present invention. The technology, shape, and structure that are not described in detail in the present invention are all known technologies.

Claims

1. A coal mine tunnel deformation monitoring sensor based on fiber Bragg grating, characterized in that: include: A polyvinyl chloride tube (1) and a bare optical fiber Bragg grating (2), wherein the polyvinyl chloride tube (1) is located in a hollow portion inside the bare optical fiber Bragg grating (2), end fixing blocks (4) are fixedly mounted on both ends of the polyvinyl chloride tube (1), an optical signal converter (5) and an optical fiber Bragg fiber gyroscope (6) are fixedly mounted on the inner and outer walls of the polyvinyl chloride tube (1), respectively, a horizontal fixing base (7) is sleeved on the outside of the polyvinyl chloride tube (1), a slot (8) is provided on the horizontal fixing base (7), and an inclination sensor (9) is mounted in the slot (8).

2. A coal mine tunnel deformation monitoring sensor based on fiber Bragg grating according to claim 1, characterized in that: A through hole for the optical fiber to extend is provided through the center position of the opposite side of the end fixing block (4).

3. A coal mine tunnel deformation monitoring sensor based on fiber Bragg grating according to claim 2, characterized in that: The outer surface of the polyvinyl chloride tube (1) is coated with silicone rubber (10), and the silicone rubber (10) forms a coating after drying.

4. A coal mine tunnel deformation monitoring sensor based on fiber Bragg grating according to claim 3, characterized in that: A plurality of holes (3) are provided through the opposite sides of the end fixing block (4), the side wall of each hole (3) is provided with an internal thread (401), a limiting nail (11) is inserted into the hole (3), and a thread groove corresponding to the hole (3) is provided on the side of the polyvinyl chloride pipe (1) facing the end fixing block (4).

5. A coal mine tunnel deformation monitoring sensor based on fiber Bragg grating according to claim 4, characterized in that: An external thread (1101) is provided on the outer side wall of the limiting pin (11), and the external thread (1101) of the limiting pin (11) is threadedly connected to the internal thread (401) and passes through the hole (3) and the thread groove to form a connection.

6. A coal mine tunnel deformation monitoring sensor based on fiber Bragg grating according to claim 5, characterized in that: Extension grooves are provided on both sides of the card slot (8), and two extension blocks (12) located in the extension grooves are fixed on both sides of the inclination sensor (9) by glue, and the extension blocks (12) are fixed inside the extension grooves by bolts.

7. A coal mine tunnel deformation monitoring sensor based on fiber Bragg grating according to claim 6, characterized in that: The number of the holes (3) is four, and the number of the limiting pins (11) is two.

8. A coal mine tunnel deformation monitoring sensor based on fiber Bragg grating according to claim 7, characterized in that: The horizontal fixing base (7) is made of metal material or fiber reinforced plastic, and the end fixing block (4) is made of epoxy resin material or metal material.

9. A coal mine tunnel deformation monitoring sensor based on fiber Bragg grating according to claim 8, characterized in that: A plurality of optical signal converters (5) are evenly arranged in a straight line on the inner wall of the polyvinyl chloride tube (1), and the optical signal converters (5) are evenly distributed on the optical fiber at intervals of 50 cm.

10. A coal mine tunnel deformation monitoring sensor based on fiber Bragg grating according to claim 9, characterized in that: An arc-shaped structure is fixedly connected to the top of the horizontal fixed base (7), and the polyvinyl chloride pipe (1) is located in the hollow part of the arc-shaped structure.

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