Angle displacement meter based on optical fiber sensing technology and installation method thereof

Abstract

The present invention discloses an angle displacement meter based on optical fiber sensing technology and an installation method thereof, characterized in that the angle displacement meter includes a guide wheel system; a sensing optical cable is wound on the guide wheel system; a high-strength epoxy adhesive is placed between the guide wheel system and the sensing optical cable; hollow connecting rods are connected through the guide wheel system and the sensing optical cable, the guide wheel system is installed on the hollow connecting rod, the sensing optical cable passes through the hollow connecting rod; the sensing optical cable is connected to a demodulator through an optical fiber jumper. In view of the fact that current technology cannot accurately realize the distributed monitoring of the internal displacement of a landslide, an angle displacement meter based on optical fiber sensing technology is provided, which can realize the distributed monitoring of the internal displacement of a landslide and reduce the strain loss in the process of transferring the structural strain to the optical fiber sensor through the deformation of the adhesive layer.

Description

Technical Field

[0001] The invention relates to an angle displacement meter based on optical fiber sensing technology and an installation method thereof, belonging to the technical field of displacement detection within a slope. Background Art

[0002] Landslides can cause huge casualties and economic losses. Landslides are affected by various factors, such as rainfall, reservoir water level, rock and soil properties, etc., so it is difficult to accurately determine the time of landslides. Landslide instability is usually accompanied by significant displacement, so accurate monitoring of landslide displacement is crucial in landslide disaster prevention and early warning.

[0003] Landslide displacement monitoring can be divided into slope surface displacement monitoring and slope internal displacement monitoring. Slope surface displacement monitoring methods (GPS, GIS, RS, SAR) can accurately monitor the displacement of a certain point on the slope surface, but cannot obtain the internal deformation information of the landslide. The internal displacement monitoring of the slope is mainly achieved through inclinometers and inclinometers. Traditional inclinometers have some shortcomings in monitoring accuracy, monitoring efficiency, anti-interference, etc., and are difficult to meet the current needs of landslide monitoring.

[0004] Fiber optic sensing is a new type of sensing technology that has developed rapidly in recent years. It uses optical fiber as a medium and light as a carrier. Compared with traditional monitoring technology, it has a series of advantages such as high sensitivity, anti-electromagnetic interference, long monitoring distance, and low cost. It has been widely used in petrochemical, aerospace, water conservancy and hydropower, civil engineering, geology and other engineering fields.

[0005] Common fiber optic sensing technologies include OFDR, OTDR, BOTDR, BOTDA, UWFBG, etc. OFDR technology is a fiber optic strain measurement technology based on the change of Rayleigh scattered light. The basic principle is to use a continuous tunable laser source, which emits a tunable swept frequency light. The light beam enters the coupler and is divided into two beams. One beam enters the reference arm and becomes the reference light; the other beam enters the test fiber. The two beams encounter the inhomogeneous medium in the fiber and will be scattered. Finally, the backward Rayleigh scattered and Fresnel reflected light in the two beams will be reflected back and interfere. The interference light will carry the frequency difference and phase difference of the two beams, which will be detected on the surface of the photodetector. After later data processing, various information carried in the optical fiber can be obtained, such as optical fiber length, strain, optical fiber breakage, fusion point, etc.

[0006] Densely distributed fiber (UWFBG), also known as weak grating, is based on time division multiplexing technology. A single fiber can be made into a densely distributed fiber with thousands of fiber grating points of the same period by online drawing and grating technology or static side exposure writing technology. This special fiber can achieve high-precision temperature and strain measurement by positioning through optical time domain reflection measurement technology after weak grating wavelength modulation. Its strain / temperature sensing principle is the same as the FBG principle, that is, the light in the incident light that meets the Bragg diffraction condition is coupled and reflected after passing through the grating, and the incident light that does not meet this condition will directly pass through the grating area, so that it appears in the form of a wavelength peak in the reflection spectrum. When the ambient temperature of the fiber core or the strain of the fiber along the axis changes, its effective refractive index and grating pitch will change, causing the center wavelength of the reflected light to drift, so that the temperature and strain can be accurately sensed. In addition, due to the small spacing and large number of grating points of densely distributed fiber, the effect of distributed continuous measurement can be achieved, because it also has the advantage of long-distance distributed monitoring that conventional FBG does not have.

[0007] From the above analysis, it is obvious that the current technology cannot accurately realize the distributed detection of internal displacement of landslides, and the traditional detection technology has the problems of low sensitivity, inability to resist electromagnetic interference, short monitoring distance and high cost. Summary of the invention

[0008] In order to overcome the problems existing in the above-mentioned technologies, an object of the present invention is to provide an angular displacement meter based on optical fiber sensing technology and an installation method thereof.

[0009] The present invention provides the following technical solutions:

[0010] An angular displacement meter based on optical fiber sensing technology is characterized in that the angular displacement meter includes a guide wheel system; a sensing optical cable is wound on the guide wheel system; a high-strength epoxy adhesive is placed between the guide wheel system and the sensing optical cable; hollow connecting rods are connected through the guide wheel system and the sensing optical cable, the guide wheel system is installed on the hollow connecting rod, and the sensing optical cable passes through the hollow connecting rod; the sensing optical cable is connected to a demodulator through an optical fiber jumper.

[0011] Specifically, the guide wheel system includes a fixed wheel and a rotating wheel, and the fixed wheel is mounted on the rotating wheel through a connecting member and fixing bolts.

[0012] Specifically, the fixed wheel is mounted on one end of the hollow connecting rod, and the rotating wheel is movably mounted on one end of the other hollow connecting rod.

[0013] Specifically, the diameter of the fixed wheel is equal to the diameter of the rotating wheel.

[0014] Specifically, the high-strength epoxy adhesive is a high-strength epoxy resin.

[0015] Specifically, the sensing optical cables are connected in series to form an articulated angular displacement meter.

[0016] Based on the above device, the present invention also proposes a method for installing the angle displacement meter, comprising the following steps:

[0017] Step 1: Use the optical fiber pulling test to determine the critical embedding length of the used sensing optical cable, to ensure that the colloid at the bonding point between the sensing optical cable and the guide wheel system through the high-strength epoxy adhesive is always in the elastic deformation stage;

[0018] Step 2, the fixed wheel is installed on the rotating wheel through a connecting member and fixing bolts;

[0019] Step 3: Install the fixed wheel on one end of the hollow connecting rod and the rotating wheel on one end of the other hollow connecting rod, wherein the fixed wheel cannot rotate, but the rotating wheel can rotate freely around the rotation center;

[0020] Step 4: The sensing optical cable is inserted into the hollow connecting rod from the small holes at both ends of the hollow connecting rod. The sensing optical cable must be wound on the fixed wheel according to the calculated fitting length and then led out, then wound on the rotating wheel, and finally passed through the connecting rod to connect with another set of guide wheel system or demodulator;

[0021] Step 5: When the sensor optical cable is wound onto the guide wheel system, it needs to be pre-stretched and fixed with a clamp. A high-strength epoxy adhesive is applied between the guide wheel system and the sensor optical cable for fixing. After the high-strength epoxy adhesive is completely solidified, the clamp is removed, and then an instrument is used to detect to ensure that the sensor optical cable is stable under tension.

[0022] Step six, finally connect the sensor optical cable to the demodulator via an optical fiber jumper.

[0023] The beneficial effects of the present invention are:

[0024] 1. In view of the fact that current technology cannot accurately realize the distributed monitoring of internal displacement of landslides, an angle displacement meter based on optical fiber sensing technology is provided. Compared with the traditional monitoring method that can only realize the displacement calculation of the shear band position, the present invention can connect multiple angle meters in series to form an articulated optical fiber displacement sensor, which can better realize the distributed displacement monitoring of the internal landslide and reduce the strain loss in the process of transferring the structural strain to the optical fiber sensor through the deformation of the adhesive layer;

[0025] 2. Fiber optic sensing is a new type of sensing technology that has developed rapidly in recent years, using fiber optic as a medium and light as a carrier. Compared with traditional monitoring technologies, the present invention has a simple structure and is easy to install. The fiber optic sensing technology has high sensitivity and accuracy, and strong reliability. It does not involve current and electromagnetics, and is resistant to electromagnetic interference, and has good safety performance. It can achieve distributed displacement monitoring of the interior of the landslide under complex conditions, which means that it has the advantages of long monitoring distance and low cost.

[0026] 3. The present invention realizes the application of optical fiber sensing in the field of slope displacement monitoring, analyzes the relationship between the strain data obtained by the demodulator and the angle of rotation of the connecting rod, and calculates the horizontal displacement of the end of the connecting rod according to the Pythagorean theorem, thereby realizing internal displacement monitoring of the slope. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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:

[0028] Figure 1 It is a structural schematic diagram of the angle displacement meter based on optical fiber sensing technology proposed by the present invention;

[0029] Figure 2 is a working principle diagram of a novel angle displacement meter based on optical fiber sensing technology in an embodiment of the present invention;

[0030] Figure 3 Schematic diagram of indoor pull-out test in an embodiment of the present invention;

[0031] Figure 4 is a strain distribution diagram of an optical cable under different load levels in an embodiment of the present invention;

[0032] Figure 5 is a strain distribution diagram of an optical cable end in an embodiment of the present invention;

[0033] Figure 6 is a comparison chart of the theoretical value and the tested value of the tensile strain of the optical cable in the embodiment of the present invention;

[0034] Figure 7 Schematic diagram of soil shear test of the angular displacement meter in an embodiment of the present invention;

[0035] Figure 8 1 is a diagram showing the results of a soil shear simulation experiment in an embodiment of the present invention.

[0036] The markings in the figure are: 101, guide wheel system; 101-1, fixed wheel; 101-2, rotating wheel; 102, hollow connecting column; 103, sensor optical cable; 104, optical fiber jumper; 105, demodulator;

[0037] 2. High-strength epoxy adhesive; 3. Tensile gauge; 4. Clamp; 5. Micrometer; 6. Angular displacement gauge. DETAILED DESCRIPTION

[0038] like Figure 1 As shown, an angle displacement meter based on optical fiber sensing technology is characterized in that the angle displacement meter includes a guide wheel system 101; a sensing optical cable 103 is wound on the guide wheel system 101; a high-strength epoxy adhesive 2 is placed between the guide wheel system 101 and the sensing optical cable 103; hollow connecting rods 102 are connected through the guide wheel system 101 and the sensing optical cable 103, the guide wheel system 101 is installed on the hollow connecting rod 102, and the sensing optical cable 103 passes through the hollow connecting rod 102; the sensing optical cable 103 is connected to the demodulator 105 through the optical fiber jumper 104.

[0039] Preferably, the guide wheel system 101 includes a fixed wheel 101-1 and a rotating wheel 101-2, wherein the fixed wheel 101-1 is mounted on the rotating wheel 101-2 via a connecting member 107 and a fixing bolt 106. The fixed wheel 101-1 is mounted on one end of the hollow connecting rod 102, and the rotating wheel 101-2 is movably mounted on one end of another hollow connecting rod 102. The diameter of the fixed wheel 101-1 is equal to the diameter of the rotating wheel 101-2.

[0040] Preferably, the high-strength epoxy adhesive 2 is a high-strength epoxy resin.

[0041] Specifically, multiple sensors are connected in series to form an articulated angular displacement meter, thereby performing long-distance angular displacement measurement.

[0042] Based on the above device, the present invention also proposes a method for installing the angle displacement meter, comprising the following steps:

[0043] Step 1: Use the optical fiber pulling test to determine the critical embedding length of the used sensing optical cable 103, to ensure that the colloid at the bonding point between the sensing optical cable 103 and the guide wheel system 101 through the high-strength epoxy adhesive 2 is always in the elastic deformation stage;

[0044] Step 2: The fixed wheel 101 - 1 is installed on the rotating wheel 101 - 2 through the connecting member 107 and the fixing bolt 106;

[0045] Step 3: Install the fixed wheel 101-1 at one end of the hollow connecting rod 102, and install the rotating wheel 101-2 at one end of the other hollow connecting rod 102, wherein the fixed wheel 101-1 cannot rotate, and the rotating wheel 101-2 can rotate freely around the rotation center;

[0046] Step 4: The sensing optical cable 103 is inserted into the hollow connecting rod 102 from the small holes at both ends of the hollow connecting rod 102. The sensing optical cable 103 must be wound on the fixed wheel 101-1 according to the calculated interlocking length and then led out, and then wound on the rotating wheel 101-2, and finally passed through the connecting rod 102 to connect with another set of guide wheel systems 101 or the demodulator 105; when the sensing optical cable 103 passes through the connecting rod 102 and is connected with another set of guide wheel systems 101, an articulated angle displacement meter can be formed;

[0047] Step 5: When the sensor optical cable 103 is wound onto the guide wheel system 101, it needs to be pre-stretched and fixed with a clamp 4. A high-strength epoxy adhesive 2 is applied between the guide wheel system 101 and the sensor optical cable 103 for fixing. After the high-strength epoxy adhesive 2 is completely solidified, the clamp 4 is removed, and then an instrument is used to detect to ensure that the sensor optical cable 103 is stable under tension;

[0048] Step six, finally connecting the sensing optical cable 103 to the demodulator 105 via the optical fiber jumper 104 .

[0049] Since the sensing optical cable 103 includes but is not limited to distributed optical fiber, quasi-distributed optical fiber, etc., different demodulators can be used to process the signal according to different distributed optical fiber technical principles, mainly including BOTDR, BOTDA, OFDR, UWFBG, etc., and optical fiber pulling tests are performed on different sensing optical cables 103 to obtain critical embedded lengths of different optical fibers.

[0050] The working principle of the present invention is:

[0051] like Figure 2 As shown, when the end of the hollow connecting rod 102 undergoes a horizontal displacement of Δl, it can be known from the trigonometric function relationship:

[0052] (1)

[0053] Among them, ɑ is the angle of rotation of the guide wheel, and S is the distance between the centers of the two guide wheels.

[0054] From the arc length formula we know that:

[0055] (2)

[0056] Where Δw is the arc length and r is the radius of the guide wheel.

[0057] The strains on the tensile and compressive sides of the optical fiber are:

[0058] (3)

[0059] (4)

[0060] Where εT is the strain of the optical cable caused by temperature.

[0061] Combining (3) and (4) can eliminate the temperature effect:

[0062] (5)

[0063] Combining (1), (2), and (5), we can obtain:

[0064] (6)

[0065] Through the relationship between the optical fiber strain ε, the displacement Δl, and the rotation angle θ, the angle and displacement changes can be calculated based on the collected strain data.

[0066] Since the embedded length of the sensing optical cable 103 on the guide wheel system 101 needs to be determined in advance through an indoor pulling test to ensure that the colloid is always in the elastic deformation stage during the strain transfer process, the strain loss in the process of transferring the structural strain to the optical fiber sensor through the deformation of the adhesive layer is reduced, and the optical fiber and the colloid are deformed synergistically to improve the measurement accuracy of the sensor.

[0067] The above-mentioned indoor optical fiber pulling test is specifically as follows:

[0068] like Figure 3 As shown, an optical cable pulling test device is designed. The experiment uses a sensing optical cable 103 with a diameter of 0.9 mm. The high-strength epoxy adhesive 2 is a high-strength epoxy resin. The length b of the two ends of the sensing optical cable 103 is respectively fixed on two rigid structures. At this time, the length b is 50 mm. The rigid structure is respectively fixed on the fixture 4 and the tensile gauge 3. The rigid structure is moved by the tensile gauge to apply a load to the sensing optical cable 103, and a load of level 10 is taken. An OFDR instrument is used, and the spatial resolution of the OFDR instrument is 1 mm and the accuracy is ±5 με for data acquisition.

[0069] The stress of the sensing optical cable 103 is equal to the product of the strain and the elastic modulus, so the variation law of the strain distribution curve of the sensing optical cable 103 is consistent with the variation law of the stress distribution curve. Figure 4 It can be seen that the strain distribution in the middle of the sensing optical cable 103 is relatively uniform. In the glue coating section, the strain of the sensing optical cable 103 gradually decreases to zero, and as the load level increases, the strain increases accordingly. In order to more accurately understand its changing law, the right side of the strain curve is enlarged to obtain Figure 5 During the first six loading processes, the variation of the strain curve was relatively consistent. When the load continued to increase, the strain curve showed irregular changes, some strains increased, and the range of strain increased. The relationship between strain and load level was analyzed by selecting 1.225m, 1.25m, and 1.275m.

[0070] Depend on Figure 6 It can be seen that when the load level is less than level 6, the strain at each location is linearly related to the load level. When the load continues to increase, the strain at 1.25m and 1.275m suddenly increases, and the change pattern is inconsistent. This is because before the load level is level 6, the colloid is in the elastic deformation stage, and the overall change trend shows a linear trend. When the load continues to increase, the colloid has a plastic deformation area, and microcracks may appear locally, so the strain change is uneven. In addition, because the length of the optical cable that provides shear stress in the elastic stage is insufficient to maintain balance with the larger load, the strain extends outward for a certain distance, allowing the optical cable to reach static equilibrium.

[0071] like Figure 6 As shown in the figure, the strain measurement value of the middle part of the optical cable is compared with the theoretical value. In the colloid elastic deformation stage, the measured value and the theoretical value are consistent, and the error changes linearly; when the elastic deformation transitions to the plastic deformation, the error suddenly increases, and the error and the load level are obviously nonlinear. The error is small and linear in the colloid elastic deformation stage, and the accuracy can be improved through indoor calibration experiments. In the plastic deformation stage, the error is large and nonlinear, which affects the accuracy and precision of the sensor.

[0072] Based on the above analysis, the critical embedding length of the 0.9 mm strain optical cable is 11 cm at an effective measurement length of 1 m, that is, the maximum embedding length in the elastic deformation stage, and the strain range of the optical cable in the elastic deformation stage is 0-6000 με. Assuming S = 1 m, r = 1 cm, it can be obtained from equations (2) and (5) that when the colloid of the sensor fixed section is in the elastic deformation stage, the calibration post-tilt angle error range is ±0.054°, and after the colloid has plastic deformation, the calibration post-tilt angle error is ±0.343°.

[0073] Therefore, when the colloid is in the elastic deformation stage, the error caused by the strain transfer of the fixed section of the optical cable can be reduced to a smaller range through indoor calibration.

[0074] In order to determine the relationship between the optical fiber strain value of the sensing optical cable 103 and the rotation angle and displacement, and to detect the accuracy of using the angle displacement meter 6, a calibration test of the new angle displacement meter 6 is carried out.

[0075] The test steps are as follows: place a lifting platform under the connecting rod, apply vertical deformation step by step, each increment is 5mm, and unload after reaching the maximum displacement of 90mm, and also decrease step by step by 5mm until reaching the original 5mm level. Each movement uses the OFDR demodulation device to detect the strain change inside the sensor. Take the average of the tensile strain and compressive strain of the stable section as the corresponding result, and the linear fitting relationship between the angle displacement meter strain and angle and displacement is as follows:

[0076] Table 1: Strain ratio coefficient table of angular displacement meter (linear fitting results)

[0077]

[0078] It can be seen from Table 1 that the linear fit of the strain, angle and displacement of the angle displacement meter is 1.0000, which shows that the angle change value and displacement calculated by the strain value are accurate.

[0079] In the above calibration test, in order to improve the linear fit of strain, angle and displacement, it is necessary to minimize the strain loss in the process of transferring the strain of the structure to the optical fiber sensor through the deformation of the adhesive layer. Therefore, based on the shear lag model proposed by Cox, the two ends of the optical cable are attached to the surface of the rigid structure through adhesive. If the fiber and the matrix are well attached, when the two rigid bodies move relative to each other, the stress acting on the optical cable will be transmitted through the interface between the optical cable and the colloid. If it is assumed that the interface is intact and the thickness is infinitely small, the colloid and the optical fiber are both elastically deformed, and the stress σ in the optical fiber and the interface shear stress τ are respectively:

[0080] (7)

[0081] (8)

[0082] (9)

[0083] Where E is the elastic modulus of the cable, G is the shear model of the colloid, a and R are the radius of the cable and the thickness of the colloid, respectively, x is the change in cable length, r is the deformation rate of the colloid, l is the aspect ratio of the cable, and β is a constant.

[0084] At the beginning of the glue-coated section, the tensile stress is the largest, the shear stress is the smallest, the optical cable and the colloid deform cooperatively, and the interlayer shear force is small; at the end of the glue-coated section, the tensile stress gradually decreases to zero, and the shear stress increases to the maximum, there is shear deformation between the optical cable and the colloid layer, and the shear force is large. Therefore, the fixed section length required to maintain static equilibrium at the assumed maximum load level of the optical cable is considered to be the critical embedding length. When the load exceeds the elastic threshold of the adhesive, a plastic zone will appear in the glue-coated section, and this model will no longer apply.

[0085] At this point, this paper studies the influence of strain transmission in the fixed section of the optical cable on the accuracy of the sensor through the pulling experiment of the optical cable. The critical embedding length of the optical cable and the load range that conforms to the elastic deformation stage of the optical cable and the colloid have been determined, ensuring that the colloid at the bonding point between the optical fiber and the guide wheel is always in the elastic deformation stage during the operation of the device, providing a reference for sensor design.

[0086] In order to more accurately confirm the applicability of the device, further soil shear tests were conducted to confirm the applicability and accuracy of the invention in the soil. The experimental device is as follows: Figure 7 As shown, the experimental steps are as follows:

[0087] Step 1: Pile up a soil slope (3.5m long, 0.3m wide, 0.3m high) in the site, connect multiple angle displacement meters 6 in series to form an articulated angle displacement sensor, and place it 0.2m away from the top of the slope, and then fill the soil.

[0088] Step 2: Place four dial gauges 5 on one side of the soil to monitor the actual displacement of the soil, and place a jack on the other side.

[0089] Step 3: Use a jack to move the wooden board (1.1m wide) placed under the soil to shear the slope model, use OFDR to monitor the sensor data, use a micrometer to record the actual shear displacement, and verify the monitoring effect of the fiber optic sensor by comparing the monitoring data of the micrometer and the fiber optic sensor.

[0090] Figure 8 This is a comparison chart of the monitoring results of the optical fiber sensor and the dial indicator. It can be seen from the figure that when the shear displacement of the soil is small, the monitoring results of the optical fiber sensor are consistent with the results of the dial indicator, and the accuracy is higher ( Figure 1 Medium load level 1-3). When the load level increases, the monitoring results of the fiber optic sensor are inconsistent with the results of the dial indicator, and the error gradually increases with the increase of the load. During the experiment, at load level 4, the model had micro cracks on the edge of the wooden board. As the load level increased, the cracks gradually increased. At the last load level, multiple obvious cracks could be observed on both sides of the wooden board. When the load level was small, the soil deformation was small, and the movement of the sensor was relatively consistent with the soil deformation. When the soil deformation was large, cracks appeared in the soil. As the cracks increased, the monitoring results of the fiber optic sensor were greater than the results of the dial indicator, and the maximum error value was 5.7mm.

[0091] To sum up, the principle of the angle displacement meter is as follows: when the connecting rod is subjected to force and rotates, it will also drive the guide wheel to rotate, and cause the strain of the sensing optical cable to change. The strain data collected by the demodulator can be converted into an angle value through calculation, and the horizontal displacement of the end of the connecting rod can be calculated according to the Pythagorean theorem.

[0092] The sensor optical cable often needs to avoid the influence of ambient temperature changes on strain measurement. When the connecting rod drives the guide wheel to rotate, one side of the sensor optical cable is the tension side and the other side is the compression side. The strain values ​​collected by the two are subtracted and the average value is calculated to eliminate the temperature error and obtain an accurate strain value.

[0093] Finally, by analyzing the relationship between the strain data obtained by the demodulator and the angle of rotation of the connecting rod, the horizontal displacement of the end of the connecting rod is calculated according to the Pythagorean theorem, thereby realizing the internal displacement monitoring of the slope.

[0094] The present invention provides an angle displacement meter based on optical fiber sensing technology. The optical fiber sensing technology used in the above embodiments is OFDR technology. It should be noted that distributed or quasi-distributed optical fiber sensing technologies including but not limited to BOTDR, BOTDA, UWFBG, etc. are also applicable. Therefore, the application of other optical fiber sensing technologies in the present invention should also be regarded as the protection scope of the present invention.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An angle displacement meter based on optical fiber sensing technology, characterized in that: The angular displacement meter includes Guide wheel system (101); A sensing optical cable (103) wound around the guide wheel system (101); A high-strength epoxy adhesive (2), wherein the high-strength epoxy adhesive (2) is applied between the guide wheel system (101) and the sensor optical cable (103); Hollow connecting rods (102), the hollow connecting rods (102) being connected via a guide wheel system (101) and a sensor optical cable (103), the guide wheel system (101) being mounted on the hollow connecting rods (102), and the sensor optical cable (103) passing through the hollow connecting rods (102); A demodulator (105), wherein the sensing optical cable (103) is connected to the demodulator (105) via an optical fiber jumper (104); The guide wheel system (101) comprises a fixed wheel (101-1) and a rotating wheel (101-2), wherein the fixed wheel (101-1) is mounted on the rotating wheel (101-2) via a connecting member (107) and a fixing bolt (106); The fixed wheel (101-1) is mounted on one end of the hollow connecting rod (102), and the rotating wheel (101-2) is movably mounted on one end of the other hollow connecting rod (102); The diameter of the fixed wheel (101-1) is equal to the diameter of the rotating wheel (101-2).

2. The angular displacement meter based on optical fiber sensing technology according to claim 1, characterized in that: The high-strength epoxy adhesive (2) is a high-strength epoxy resin.

3. The angular displacement meter based on optical fiber sensing technology according to claim 1 or 2, characterized in that: The sensing optical cables (103) are connected in series to form an articulated angular displacement meter.

4. A method for installing the angle displacement meter based on optical fiber sensing technology according to claim 3, characterized in that: The following steps are involved: a) determining the critical embedding length of the used sensing optical cable (103) by means of an optical fiber pulling test, so as to ensure that the colloid at the bonding point between the sensing optical cable (103) and the guide wheel system (101) by means of the high-strength epoxy adhesive (2) is always in an elastic deformation stage; b) the fixed wheel (101-1) is mounted on the rotating wheel (101-2) via a connecting member (107) and a fixing bolt (106); c) installing a fixed wheel (101-1) on one end of a hollow connecting rod (102), and installing a rotating wheel (101-2) on one end of another hollow connecting rod (102), wherein the fixed wheel (101-1) cannot rotate, while the rotating wheel (101-2) can rotate freely around a rotation center; d) The sensing optical cable (103) is inserted into the hollow connecting rod (102) through the small holes at both ends of the hollow connecting rod (102). The sensing optical cable (103) is wound on the fixed wheel (101-1) according to the calculated interlocking length and then led out, and then wound on the rotating wheel (101-2), and finally passed through the connecting rod (102) to be connected to another set of guide wheel systems (101) or a demodulator (105); e) When the sensor optical cable (103) is wound onto the guide wheel system (101), it needs to be pre-tensioned and fixed with a clamp (4), and a high-strength epoxy adhesive (2) is applied between the guide wheel system (101) and the sensor optical cable (103) for fixing. After the high-strength epoxy adhesive (2) is completely solidified, the clamp (4) is removed, and an instrument is used to detect and ensure that the sensor optical cable (103) is stable under tension; f) Finally, the sensing optical cable (103) is connected to a demodulator (105) via an optical fiber jumper (104).

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