A slope inclinometer tube deformation monitoring system

Abstract

The invention belongs to the field of geotechnical engineering monitoring. Aiming at the problems of low spatial resolution, complex laying, and measurement results being easily affected by temperature in the existing optical fiber monitoring system for deformation of slope inclinometer tubes, the invention discloses a deformation monitoring system for slope inclinometer tubes, comprising: a swept frequency laser, a light splitting unit, an optical circulator, a sensing optical fiber, a first light combiner, a first polarization beam splitter, a first balanced light detector, a delay optical fiber, a second light combiner, a second polarization beam splitter, a second balanced light detector, a computer and an inclinometer tube. The invention uses a single optical fiber to perform strain monitoring and temperature compensation at the same time, so as to realize long-term remote real-time monitoring of the slope inclinometer tube, and has the advantages of high spatial resolution, convenient laying, no temperature cross-sensitivity problem, and the like.

Description

Technical Field

[0001] The invention relates to the field of geotechnical engineering monitoring, and in particular to a slope inclinometer tube deformation monitoring system. Background Art

[0002] In western my country, due to the complex distribution of terrain, severe soil erosion caused by droughts and floods, and weathering, and fragile geological environmental conditions, coupled with the rapid development of economic construction, various engineering activities have intensified the impact of terrain changes. For example, areas such as slope cutting for building houses and mountain road construction are more likely to experience landslide disasters.

[0003] Sudden disasters such as landslides are extremely destructive, so all aspects of society have strengthened the monitoring of landslide disasters, and the monitoring of geological disasters has become more and more mature. There are methods for monitoring surface deformation, such as GPS, close-range photography, and geodetic measurement, but these methods cannot reflect the deformation of the deep soil in a timely manner; underground monitoring methods include discrete measurement systems and distributed measurement systems.

[0004] The discrete measurement system mainly uses inclination sensors to measure the slope changes of the slope inclinometer tube at equidistant positions, and then converts the displacement of each point. The commonly used inclinometer sensors in this method include electrical inclinometer sensors and multi-point fiber optic inclinometer sensors. Electrical inclinometer sensors are cheap and highly accurate, but they are complicated to operate and have poor reliability due to their susceptibility to electromagnetic interference and long-term power supply difficulties. Multi-point fiber optic inclinometer sensors use optical fibers or fiber gratings to measure the inclination angle of the inclinometer, and convert the measured angle into the displacement value of the inclinometer. However, this method can only measure the inclination of a few points when applied, and judge the state of the inclinometer tube by the local displacement value. The spatial resolution is low and there are large errors. The distributed measurement system can achieve high spatial resolution and more accurately reflect the deformation of the inclinometer tube, so it is more widely used.

[0005] The distributed measurement system mainly measures the stress changes of the optical fiber attached to the inclinometer tube, and reflects the displacement of the deep soil in real time through the deformation state of the inclinometer tube. Currently, the most commonly used distributed measurement system is the fiber optic Brillouin sensing technology, which can achieve distributed measurement, but due to the limitation of the measurement mechanism, its spatial resolution is still low, and it is impossible to achieve high-precision and high-spatial-resolution distributed measurement.

[0006] Optical frequency domain reflectometry (OFDR) technology has become the focus of distributed measurement system research due to its advantages of high precision and high spatial resolution. The sensing fiber is laid outside the inclinometer tube, and the OFDR system is used to measure the real-time deformation state of the inclinometer tube with high precision and high spatial resolution, which corresponds to the deep displacement of the soil. At the same time, in order to solve the impact of temperature changes caused by climate on the measurement system, additional temperature compensation data is required to compensate the measurement data. The traditional compensation method is to perform temperature compensation by laying a free optical fiber in parallel with an empty sleeve. This method not only makes the layout more complicated, but also the position of the temperature compensation optical fiber will be greatly offset when the deformation variable of the inclinometer tube is large, resulting in inaccurate compensation. Summary of the invention

[0007] The present invention overcomes the shortcomings of the prior art and aims to solve the following technical problems: to provide a slope inclinometer tube deformation monitoring system, which is based on optical fiber and grating hybrid sensing, optical frequency domain reflection distributed strain sensing technology, dual interference phase noise compensation and polarization diversity reception technology, simplifies the layout scheme and improves the system monitoring accuracy through the fusion of weak reflection grating array and optical frequency domain reflection sensing system, and can be used to solve the problems of long-term remote real-time high spatial resolution monitoring of slope inclinometer tube deformation and complex layout.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a slope inclinometer tube deformation monitoring system, comprising: a frequency sweeping laser, a light splitting unit, an optical circulator, a sensing optical fiber, a first light combiner, a first polarization beam splitter, a first balanced light detector, a delay optical fiber, a second light combiner, a second polarization beam splitter, a second balanced light detector, a computer and an inclinometer tube;

[0009] The output end of the frequency-sweeping laser is connected to the input end of the optical splitter unit, the optical splitter unit includes four output ends, and is used to split the output light of the frequency-sweeping laser into four beams, the output end B of the optical splitter unit is connected to the first port of the optical circulator, the second port of the optical circulator is connected to the sensing optical fiber, the third port of the optical circulator is connected to the F port of the first light combiner, the output end G of the optical splitter unit is connected to the H port of the first light combiner, the output end of the first light combiner is connected to the input end of the first polarization beam splitter, and the two output ends of the first polarization beam splitter are respectively connected to the two input ends of the first balanced light detector;

[0010] The output end M of the light splitting unit is connected to the input end N of the second light combiner, the output end O of the light splitting unit is connected to the input end P of the second light combiner via a delay optical fiber, the output end of the second light combiner is connected to the input end of the second polarization beam splitter, and the two output ends of the second polarization beam splitter are respectively connected to the two input ends of the second balanced light detector;

[0011] The input end of the computer is connected to the output ends of the first balanced light detector and the second balanced light detector, and the input end of the computer is also connected to the synchronization signal output end of the frequency sweeping laser; the computer is used to calculate the optical frequency domain reflection signal according to the detection signal of the first balanced light detector, and calculate the phase noise information according to the detection signal of the second balanced light detector, and calculate the deformation monitoring information along the sensing optical fiber after performing phase compensation on the optical frequency domain reflection signal according to the phase noise signal;

[0012] The sensing optical fiber is fixedly arranged on the inclinometer tube.

[0013] The slope inclinometer tube deformation monitoring system also includes a connecting tube. There are multiple inclinometer tubes, and four installation grooves are arranged on the outer circumference of the inclinometer tubes, which are distributed at an interval of 90°. One of the installation grooves is used to lay the sensing optical fiber. A pair of protruding positioning blocks with a relative position of 180° are arranged on the inner side of the connecting tube. The positioning blocks cooperate with the two installation grooves on the inclinometer tube to connect two adjacent inclinometer tubes.

[0014] The slope inclinometer tube deformation monitoring system also includes a first polarization controller and a second polarization controller, wherein the first polarization controller is arranged between the output end G of the splitter unit and the H port of the first light combiner, and the second polarization controller is arranged between the output end M of the splitter unit and the N port of the second light combiner.

[0015] The slope inclinometer tube deformation monitoring system also includes a first continuous optical amplifier and a second continuous optical amplifier, wherein the first continuous optical amplifier is arranged between the output end B of the splitter unit and the first port C of the optical circulator, and the second continuous optical amplifier is arranged between the third port E of the optical circulator and the input end F of the first light combiner.

[0016] A plurality of reflection gratings are arranged at equal intervals on the sensing optical fiber to form a grating array.

[0017] The central wavelength of the frequency sweeping laser is 1550nm, the frequency sweeping range is 1540nm to 1560nm, the central wavelength of the reflection grating is 1553.9nm, the reflectivity is less than 2%, and the distance between two adjacent reflection gratings is 40-100cm.

[0018] The computer is used to obtain the reflection signals of each reflection grating and the optical frequency domain reflection signal in the sensing optical fiber according to the detection signal of the first balanced light detector, and to perform temperature compensation on the optical frequency domain reflection signal of the sensing optical fiber around the reflection grating according to the data of each reflection grating, so as to obtain deformation monitoring information along the sensing optical fiber.

[0019] The optical splitting unit includes a first optical fiber coupler, a second optical fiber coupler and a third optical fiber coupler. The input end of the first optical fiber coupler is connected to the laser output end of the frequency-sweeping laser. The output end A and the output end L of the first optical fiber coupler are respectively connected to the input ends of the second optical fiber coupler and the third optical fiber coupler. The two output ends of the second optical fiber coupler are respectively the output end B and the output end G of the optical splitting unit. The two output ends of the third optical fiber coupler are respectively the output end M and the output end O of the optical splitting unit.

[0020] The splitting ratio between the output end A and the output end L of the first optical fiber coupler is 90:10, the splitting ratio between the output end B and the output end G of the second optical fiber coupler is 90:10, and the splitting ratio between the output end M and the output end O of the third optical fiber coupler is 50:50.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. Different from the existing inclinometer tube deformation monitoring technology, the present invention provides a slope inclinometer tube deformation monitoring system. On the basis of using OFDR technology to ensure high precision and high spatial resolution, a single sensing optical fiber engraved with a temperature compensation grating is used to monitor the strain of the inclinometer tube, which simplifies the layout plan and can achieve long-term remote real-time monitoring. Frequent manual on-site monitoring is not required, the monitoring results are more accurate, and the deformation of the slope can be fed back in real time. It has higher reliability, solves the problems of power supply and electromagnetic interference, and can timely and reliably warn of the occurrence of disasters to reduce losses.

[0023] 2. The present invention is based on optical fiber and grating hybrid sensing, optical frequency domain reflection distributed strain sensing technology, dual interference phase noise compensation and polarization diversity reception technology. The integrated system has multiple advantages and makes up for the main disadvantages. The optical fiber and grating hybrid sensing method is used to measure the deformation of the inclinometer tube and perform temperature compensation. It can compensate for the phase noise of the system, reduce polarization fading, improve the signal-to-noise ratio and spatial resolution, further enhance the real-time and accurate monitoring capability of the system, and better reflect the deformation of the inclinometer tube.

[0024] 3. In addition, based on the design of a high spatial resolution real-time monitoring system, the present invention simplifies the layout scheme and enhances the applicability and operability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the structure of a slope inclinometer tube deformation monitoring system provided in Embodiment 1 of the present invention;

[0026] Figure 2 It is a schematic diagram of the layout of the inclinometer tube in the first embodiment of the present invention;

[0027] Figure 3Schematic diagram of the cross-sectional structure of the inclinometer tube and the connecting tube in the first embodiment of the present invention;

[0028] Figure 4 A schematic diagram of the structure of a slope inclinometer tube deformation monitoring system provided in the second embodiment of the present invention;

[0029] Among them, the figure markings are: 1-sweep frequency laser, 2-first fiber coupler, 3-second fiber coupler, 4-first continuous light amplifier, 5-optical circulator, 6-sensing fiber, 7-second continuous light amplifier, 8-first polarization controller, 9-first light combiner, 10-first polarization beam splitter, 11-first balanced light detector, 12-third fiber coupler, 13-second polarization controller, 14-delay fiber, 15-second light combiner, 16-second polarization beam splitter, 17-second balanced light detector, 18-computer, 19-inclinometer tube, 20-connecting tube, 21-reflection grating. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] Embodiment 1

[0032] like Figures 1-2 As shown, Embodiment 1 of the present invention provides a slope inclinometer tube deformation monitoring system, comprising: a swept frequency laser 1, a light splitting unit, an optical circulator 5, a sensing optical fiber 6, a first light combiner 9, a first polarization beam splitter 10, a first balanced light detector 11, a delay optical fiber 14, a second light combiner 15, a second polarization beam splitter 16, a second balanced light detector 17, a computer 18 and an inclinometer tube 19.

[0033] Among them, the output end of the sweeping laser 1 is connected to the input end of the splitter unit, the splitter unit includes four output ends, which are used to split the output light of the sweeping laser 1 into four beams, the output end B of the splitter unit is connected to the first port C of the optical circulator 5, the second port D of the optical circulator 5 is connected to the sensing optical fiber 6, the third port E of the optical circulator 5 is connected to the F port of the first light combiner 9, the output end G of the splitter unit is connected to the H port of the first light combiner 9, the output end of the first light combiner 9 is connected to the input end of the first polarization beam splitter 10, and the two output ends of the first polarization beam splitter 10 are respectively connected to the two input ends of the first balanced light detector 11; the output end M of the splitter unit is connected to the N input end of the second light combiner 15, and the output end O of the splitter unit is connected to the second light combiner 15 via the delay optical fiber 14. The input end P of the second light combiner 15 is connected to the input end of the second polarization beam splitter 16, and the two output ends of the second polarization beam splitter 16 are respectively connected to the two input ends of the second balanced light detector 17; the input end of the computer 18 is connected to the output ends of the first balanced light detector 11 and the second balanced light detector 17, and the input end of the computer 18 is also connected to the synchronization signal output end of the swept laser 1; the computer 18 is used to calculate the optical frequency domain reflection signal according to the detection signal of the first balanced light detector 11, and calculate the phase noise information according to the detection signal of the second balanced light detector 17, and calculate the deformation monitoring information along the sensing optical fiber 6 after performing phase compensation on the optical frequency domain reflection signal according to the phase noise signal.

[0034] Specifically, Figure 2 As shown, the sensing optical fiber 6 is fixedly arranged on the inclinometer tube 19 .

[0035] Furthermore, if Figure 3 As shown, the inclinometer tube 19 is a hollow PVC cylindrical rod with a single section length of two meters. It is provided with four mounting grooves on the outside, which are distributed at intervals of 90°. It can be used to lay optical fibers. Furthermore, if multiple inclinometer tubes 19 are required, a slope inclinometer tube deformation monitoring system of this embodiment also includes a connecting tube 20, and the inclinometer tubes 19 are connected with the connecting tube 20. The single section length of the connecting tube 20 is 200-400mm, and there is a pair of protruding positioning blocks with a relative position of 180° inside. The positioning blocks cooperate with the two mounting grooves on the inclinometer tube 19 to connect two adjacent inclinometer tubes 19.

[0036] Arrange the inclinometer tubes 19 and the connecting tubes 20 on the ground in sequence, pass the sensing optical fiber 6 from the installation groove on one side to the bottom of the last inclinometer tube 19, and make a loop at the tail end to weaken the Fresnel reflection. Then pre-stretch the strain sensing optical fiber 6 to make it close to the inclinometer tube 19 and fix the strain sensing optical fiber 6 in the installation groove with epoxy resin. Then use screws to tightly connect the connecting tube 20 and the two inclinometer tubes 19, and the screws should not damage the optical fiber. Finally, use a rubber cover to seal the end of the last inclinometer tube 19 to prevent foreign objects from entering during the installation process.

[0037] Place the inclinometer tube 19 in the well-drilled installation hole, put the bottom with the rubber cover into the installation hole first, and ensure that the inclinometer tube 19 extends vertically to the bottom of the installation hole.

[0038] The inclinometer tube 19 is rotated so that the pair of mounting grooves where the strain sensing optical fibers 6 are located are consistent with the inclination direction of the measured slope.

[0039] Backfill material is filled between the inclinometer tube 19 and the mounting hole to fix the inclinometer tube 19 .

[0040] After the system is deployed, the deformation of the inclinometer tube 19 caused by the displacement of the soil will cause the sensing optical fiber 6 to deform synchronously. A rectangular coordinate system is established with the center of the inclinometer tube 19 as the origin, the direction parallel to the slope as the x-axis, and the direction perpendicular to the slope as the y-axis. Since the soil usually moves in the x-axis direction, the inclinometer tube 19 will deform with the movement of the soil, and at the same time, the sensing optical fiber 6 will be partially tensile strained. Therefore, the strain on the strain sensing optical fiber 6 caused by the deformation of the inclinometer tube 19 caused by the displacement of the soil can be obtained through strain sensing based on optical frequency domain reflection technology.

[0041] In this embodiment, the frequency sweeping laser 1 periodically emits a linear frequency sweeping optical signal with a constant amplitude, continuous phase, a central wavelength of 1550nm, and a frequency sweeping range of 1540nm to 1560nm. The first light combiner 9 and the second light combiner 15 can be fiber couplers with a splitting ratio of 1:1. The light splitting unit can be a 1×4 fiber coupler, or a combination of multiple other binary splitting devices, for example, a light beam is split into two beams by a binary splitting device, and then the two beams are split into two beams by two binary splitting devices to obtain a total of 4 beams. The binary splitting device can be a 45° beam splitter or a 1×2 fiber coupler.

[0042] Specifically, Figure 1As shown, in this embodiment, a plurality of reflection gratings 21 are evenly spaced on the sensing optical fiber 6 to form a grating array. The central wavelength of the reflection grating 21 is 1553.9 nm, the reflectivity is less than 2%, and the distance between two adjacent reflection gratings 21 is 40 to 100 cm. Specifically, in this embodiment, the reflectivity of the reflection grating 21 is preferably 1%, and the distance between two adjacent reflection gratings 21 is 50 cm. Since both the reflection grating 21 and the OFDR are sensitive to temperature and strain, the signal measured by the distributed reflection grating 21 is used to perform temperature compensation on the OFDR strain signal of the optical fiber around the reflection grating 21. According to the obtained strain and temperature information, the bending conditions of each position of the inclinometer tube 19 can be restored in real time, and then the deep displacement of the soil can be monitored in real time to achieve distributed shape sensing.

[0043] In this embodiment, the linear frequency sweeping optical signal emitted by the frequency sweeping laser 1 is divided into four beams after passing through the optical splitting unit, of which two beams are detection light and reference light, and the other two beams are standard light and delayed light. The detection light is output to the first port C of the optical circulator 5, and is output to the sensing optical fiber 6 from the second port D of the optical circulator 5. The sensing optical fiber 6 is backscattered and returns to the second port D of the optical circulator 5, and enters the input end F of the first optical combiner 9 after being output from the third port E; the reference light enters the input end H of the first optical combiner 9. The backscattered light of the sensing optical fiber 6 entering the input end F of the first optical combiner 9 is combined with the reference light entering the input end H of the first optical combiner 9 in a ratio of 1:1 to form the main interference combined light, and is output to the first polarization beam splitter 10 to be divided into a fast axis component and a slow axis component with mutually orthogonal polarization states. Among them, the fast axis component of the main interference combined light is formed by combining the fast axis component of the backscattered light of the sensing optical fiber 6 and the fast axis component of the reference light, and is output to the input end I of the first balanced light detector 11; the slow axis component of the main interference combined light is formed by combining the slow axis component of the backscattered light of the sensing optical fiber 6 and the slow axis component of the reference light, and is output to the input end J of the first balanced light detector 11; in the first balanced photoelectric detector 11, the fast axis component of the backscattered light of the sensing optical fiber 6 and the fast axis component of the reference light coherently beat and are converted into electrical signals to obtain the main interference fast axis beat signal; the slow axis component of the backscattered light of the sensing optical fiber 6 and the slow axis component of the reference light coherently beat and are converted into electrical signals to obtain the main interference slow axis beat signal. The first balanced photoelectric detector outputs the difference signal of the main interference fast axis beat signal and the main interference slow axis beat signal to the K port of the computer 18, realizing polarization diversity reception of two orthogonal polarized lights, reducing the signal-to-noise ratio deterioration caused by polarization fading, and improving the system signal-to-noise ratio. The computer 18 receives the signal from the main interference system from the input port K, and demodulates the weak reflection grating signal and the optical frequency domain reflection signal respectively. Since the temperature of the soil layer is gradually changing, the strain sensing signal of the sensing optical fiber 6 around the reflection grating 21 is temperature compensated by the data measured by each reflection grating 21 to obtain a more accurate deformation monitoring signal.

[0044] Among them, the standard light is input to the input end N of the second light combiner 15, and the delayed light is output to the input end P of the second light combiner 15 through the delay optical fiber 14. The second light combiner 15 combines the standard light from the input end N and the delayed light from the input end P in a 1:1 ratio into auxiliary interference combined light, and outputs it to the input end of the second polarization beam splitter 16, and is divided into a fast axis component and a slow axis component with mutually orthogonal polarization states through the second polarization beam splitter 16. Among them, the fast axis component of the auxiliary interference combined light is formed by combining the fast axis component of the standard light and the fast axis component of the delayed light, and is output to the input end Q of the second balanced light detector 17; the slow axis component of the auxiliary interference combined light is formed by combining the slow axis component of the standard light and the slow axis component of the delayed light, and is output to the input end R of the second balanced light detector 17; in the second balanced photodetector 17, the fast axis component of the standard light and the fast axis component of the delayed light coherently beat and are converted into electrical signals to obtain an auxiliary interference fast axis beat signal; the slow axis component of the standard light and the slow axis component of the delayed light coherently beat and are converted into electrical signals to obtain an auxiliary interference slow axis beat signal. The second balanced photodetector outputs the differential signal of the auxiliary interference fast axis beat signal and the auxiliary interference slow axis beat signal to the S port of the computer 18, realizing polarization diversity reception of two orthogonal polarized lights, reducing the signal-to-noise ratio deterioration caused by polarization fading, and improving the system signal-to-noise ratio. The computer 18 receives the signal from the auxiliary interference system from the input port S and analyzes it to obtain the system phase noise information to compensate for the phase noise of the signal from the main interference system, thereby reducing the phase noise of the strain sensing signal of the sensing optical fiber 6.

[0045] The frequency sweeping laser 1 emits a pulse generating signal synchronized with the frequency sweeping, and the synchronized pulse generating signal is output to the input terminal T of the computer 18 as a signal acquisition start trigger signal of the computer 18, thereby realizing the time synchronization between the laser frequency sweeping and the signal acquisition.

[0046] Specifically, in this embodiment, the computer 18 is used to obtain the reflection signals of each reflection grating 21 and the optical frequency domain reflection signal in the sensing optical fiber 6 according to the detection signal of the first balanced optical detector 11, and to perform temperature compensation on the optical frequency domain reflection signal of the sensing optical fiber 6 around the reflection grating 21 according to the data of each reflection grating 21, so as to obtain the deformation monitoring information along the sensing optical fiber 6. After the computer 18 completes the collection and processing of the deformation measurement data of the inclinometer tube 19, it is also used to determine whether there is a risk of geological disasters according to the set threshold standard, and issue a geological disaster warning level, and summarize and upload the measurement and warning data to the cloud to achieve real-time feedback.

[0047] Embodiment 2

[0048] like Figure 4As shown, the second embodiment of the present invention provides a slope inclinometer tube deformation monitoring system, which is the same as the first embodiment in that it includes: a swept laser 1, a splitter unit, an optical circulator 5, a sensing optical fiber 6, a first light combiner 9, a first polarization beam splitter 10, a first balanced light detector 11, a delay optical fiber 14, a second light combiner 15, a second polarization beam splitter 16, a second balanced light detector 17, a computer 18 and an inclinometer tube 19.

[0049] Different from the first embodiment, the present embodiment further includes a first polarization controller 8 and a second polarization controller 13, wherein the first polarization controller 8 is arranged between the output end G of the light splitting unit and the H port of the first light combiner 9, and the second polarization controller 13 is arranged between the output end M of the light splitting unit and the N port of the second light combiner 15. The first polarization controller 8 is used to adjust the polarization of the reference light, thereby adjusting the power of the reference light entering the first light combiner 9. By adjusting the first polarization controller 8, the power of the main interference fast-axis beat signal and the main interference slow-axis beat signal can be made close, so that the first balanced photodetector 11 can obtain the differential signal of the main interference fast-axis beat signal and the main interference slow-axis beat signal. The second polarization controller 13 is used to adjust the polarization of the standard light, thereby adjusting the power of the standard light entering the second light combiner 15. By adjusting the second polarization controller 13, the power of the auxiliary interference fast-axis beat signal and the auxiliary interference slow-axis beat signal can be made close, so that the second balanced photodetector 17 can obtain the differential signal of the auxiliary interference fast-axis beat signal and the auxiliary interference slow-axis beat signal. In addition, the power can also be adjusted by setting an optical attenuator or other methods.

[0050] Furthermore, different from the first embodiment, the slope inclinometer pipe deformation monitoring system of the present embodiment further includes a first continuous optical amplifier 4 and a second continuous optical amplifier 7, wherein the first continuous optical amplifier 4 is arranged between the output end B of the light splitting unit and the first port C of the optical circulator 5, and the second continuous optical amplifier 7 is arranged between the third port E of the optical circulator 5 and the input end F of the first light combiner 9. The power of the detection light entering the sensing optical fiber 6 can be amplified by the first continuous optical amplifier 4 to increase the signal ratio of the system, and the power of the backscattered light generated in the sensing optical fiber 6 can be amplified by the second continuous optical amplifier 7 to further increase the signal ratio of the system.

[0051] Furthermore, in the present embodiment, the optical splitting unit comprises a first optical fiber coupler 2, a second optical fiber coupler 3 and a third optical fiber coupler 12, the input end of the first optical fiber coupler 2 is connected to the laser output end of the frequency-sweeping laser 1, the output end A and the output end L of the first optical fiber coupler 2 are respectively connected to the input ends of the second optical fiber coupler 3 and the third optical fiber coupler 12, the two output ends of the second optical fiber coupler 3 are respectively the output end B and the output end G of the optical splitting unit, and the two output ends of the third optical fiber coupler 12 are respectively the output end M and the output end O of the optical splitting unit.

[0052] Specifically, in this embodiment, the splitting ratio of the output end A and the output end L of the first optical fiber coupler 2 is 90:10. The splitting ratio of the two output ports of the second optical fiber coupler 3 is 90:10, that is, the splitting ratio of port B to port G is 90:10, and the splitting ratio of the two output ports of the third optical fiber coupler 12 is 50:50, that is, the splitting ratio of port M to port O is 50:50.

[0053] 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 it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A slope inclinometer tube deformation monitoring system, characterized in that: include: A frequency sweeping laser (1), a light splitting unit, an optical circulator (5), a sensing optical fiber (6), a first light combiner (9), a first polarization beam splitter (10), a first balanced optical detector (11), a delay optical fiber (14), a second light combiner (15), a second polarization beam splitter (16), a second balanced optical detector (17), a computer (18), and an inclinometer tube (19); The output end of the frequency sweeping laser (1) is connected to the input end of the light splitting unit, the light splitting unit comprises four output ends and is used to split the output light of the frequency sweeping laser (1) into four beams, the output end B of the light splitting unit is connected to the first port of the optical circulator (5), the second port of the optical circulator (5) is connected to the sensing optical fiber (6), the third port of the optical circulator (5) is connected to the F port of the first light combiner (9), the output end G of the light splitting unit is connected to the H port of the first light combiner (9), the output end of the first light combiner (9) is connected to the input end of the first polarization beam splitter (10), and the two output ends of the first polarization beam splitter (10) are respectively connected to the two input ends of the first balanced light detector (11); The output end M of the light splitting unit is connected to the input end N of the second light combiner (15); the output end O of the light splitting unit is connected to the input end P of the second light combiner (15) via the delay optical fiber (14); the output end of the second light combiner (15) is connected to the input end of the second polarization beam splitter (16); and the two output ends of the second polarization beam splitter (16) are respectively connected to the two input ends of the second balanced light detector (17); The input end of the computer (18) is connected to the output ends of the first balanced light detector (11) and the second balanced light detector (17), and the input end of the computer (18) is also connected to the synchronization signal output end of the frequency sweeping laser (1); the computer (18) is used to calculate the optical frequency domain reflection signal according to the detection signal of the first balanced light detector (11), and calculate the phase noise information according to the detection signal of the second balanced light detector (17), and calculate the deformation monitoring information along the sensing optical fiber (6) after performing phase compensation on the optical frequency domain reflection signal according to the phase noise signal; The sensing optical fiber (6) is fixedly mounted on the inclinometer tube (19); and further comprising a connecting tube (20). The inclinometer tube (19) has a plurality of tubes, and four mounting grooves are arranged on the outer circumference thereof, which are arranged at intervals of 90°, one of which is used to lay the sensing optical fiber (6). The inner side of the connecting tube (20) is provided with a pair of protruding positioning blocks with a relative position of 180°, and the positioning blocks cooperate with the two mounting grooves on the inclinometer tube (19) to connect two adjacent inclinometer tubes (19); A plurality of reflection gratings (21) are arranged at equal intervals on the sensing optical fiber (6) to form a grating array; The computer (18) is used to obtain the reflection signals of each reflection grating (21) and the optical frequency domain reflection signal in the sensing optical fiber (6) according to the detection signal of the first balanced optical detector (11), and to perform temperature compensation on the optical frequency domain reflection signal of the sensing optical fiber (6) around the reflection grating (21) according to the data of each reflection grating (21), so as to obtain deformation monitoring information along the sensing optical fiber (6).

2. A slope inclinometer tube deformation monitoring system according to claim 1, characterized in that: It also includes a first polarization controller (8) and a second polarization controller (13), wherein the first polarization controller (8) is arranged between the output end G of the light splitting unit and the H port of the first light combiner (9), and the second polarization controller (13) is arranged between the output end M of the light splitting unit and the N port of the second light combiner (15).

3. A slope inclinometer tube deformation monitoring system according to claim 1, characterized in that: The invention also comprises a first continuous optical amplifier (4) and a second continuous optical amplifier (7), wherein the first continuous optical amplifier (4) is arranged between an output end B of the optical splitter unit and a first port C of the optical circulator (5), and the second continuous optical amplifier (7) is arranged between a third port E of the optical circulator (5) and an input end F of the first optical combiner (9).

4. A slope inclinometer tube deformation monitoring system according to claim 1, characterized in that: The central wavelength of the frequency sweeping laser (1) is 1550 nm, the frequency sweeping range is 1540 nm to 1560 nm, the central wavelength of the reflection grating (21) is 1553.9 nm, the reflectivity is less than 2%, and the distance between two adjacent reflection gratings (21) is 40 to 100 cm.

5. The slope inclinometer tube deformation monitoring system according to claim 1, characterized in that: The optical splitter unit comprises a first optical fiber coupler (2), a second optical fiber coupler (3) and a third optical fiber coupler (12); the input end of the first optical fiber coupler (2) is connected to the laser output end of the frequency-sweeping laser (1); the output end A and the output end L of the first optical fiber coupler (2) are respectively connected to the input ends of the second optical fiber coupler (3) and the third optical fiber coupler (12); the two output ends of the second optical fiber coupler (3) are respectively the output end B and the output end G of the optical splitter unit; the two output ends of the third optical fiber coupler (12) are respectively the output end M and the output end O of the optical splitter unit.

6. A slope inclinometer tube deformation monitoring system according to claim 5, characterized in that: The splitting ratio between the output end A and the output end L of the first optical fiber coupler (2) is 90:10, the splitting ratio between the output end B and the output end G of the second optical fiber coupler (3) is 90:10, and the splitting ratio between the output end M and the output end O of the third optical fiber coupler (12) is 50:50.

Images