High-precision continuous optical fiber displacement sensor

Abstract

The utility model provides a high-precision continuous optical fiber displacement sensor, which is applied to the technical field of optical fiber sensors and comprises a displacement beam connected with a displacement beam mounting base. The two ends of the displacement beam mounting base are respectively connected with wire pressing terminals, one wire pressing terminal is connected with an optical cable protection sleeve, and the other wire pressing terminal is connected with a connecting lead; one side of the displacement beam mounting base is connected with a pull rod outer tube, a pull rod is arranged in the pull rod outer tube, one end of the pull rod is connected with a spring, the spring is connected with the displacement beam through a steel wire rope, and the other end of the pull rod is provided with mounting threads for connecting a measured object or a displacement beam mounting base of a next optical fiber displacement sensor; the upper surface of the displacement beam is provided with a strain grating, and the temperature compensation grating pasting wall is provided with a temperature grating. The multiple sensors are connected end to end, tunnel joint deformation at different positions can be monitored at the same time, the displacement change of the external detected tunnel joint is reflected through compression and stretching of the high-strength strain grating, the response is sensitive, and the precision is high.

Description

Technical Field

[0001] The utility model belongs to the technical field of optical fiber sensors, and in particular relates to a high-precision continuous optical fiber displacement sensor. Background Art

[0002] Since its introduction, fiber Bragg grating has been widely used in the field of fiber optic sensing. Fiber Bragg grating sensors have attracted more and more attention due to their advantages such as anti-electromagnetic interference, anti-corrosion, electrical insulation, high sensitivity, low cost, and good compatibility with ordinary optical fibers. Since the resonant wavelength of fiber Bragg grating is sensitive to changes in stress, strain and temperature, it is mainly used for the measurement of temperature, stress and strain.

[0003] For subway tunnel engineering structure monitoring, an ideal subway tunnel engineering monitoring system should have the following characteristics: it can obtain information and change process of structural deformation in all sections and in all directions, grasp the stability of the tunnel, provide data change information in a timely manner, and evaluate and feedback on possible dangerous situations; it can provide reliable data and scientific basis for the correct analysis, evaluation, prediction and forecast of disasters such as excessive deformation and water seepage; at the same time, the monitoring results are also an important basis for testing the effect of the lining structure and the surrounding rock, and can provide parameters for related analysis and numerical calculations.

[0004] The monitoring of subway tunnel structure deformation mainly includes uneven tunnel settlement, convergence of annular structure, deformation of segment structure, expansion and contraction of segment joints, etc. Structural deformation can reflect the deformation law of surrounding rock and the structure itself. By monitoring the structural deformation, reasonably adjusting the construction parameters according to the deformation development rate and trend, and taking corresponding technical measures, the deformation of surrounding rock can be minimized. After the shield construction of the subway tunnel is completed, the surrounding rock is closed by the support structure, and the effect of the surrounding rock on the segment structure cannot be directly measured. Therefore, the structural deformation monitoring of the shield tunnel is mainly based on the deformation measurement of the support structure. However, these methods are affected by the inability to take into account both continuous distribution monitoring and high-precision monitoring at the same time, resulting in the current subway tunnel structure deformation monitoring has not been able to achieve a good early warning effect. Utility Model Content

[0005] In view of the above problems in the prior art, the purpose of the utility model is to provide a high-precision continuous optical fiber displacement sensor. Multiple sensors are connected end to end to form a continuous optical fiber displacement sensor, which can simultaneously monitor the deformation of tunnel joints at different positions, and reflect the displacement changes of the measured tunnel joints in the outside world through the compression and stretching of the high-strength strain grating. It has sensitive response and high precision.

[0006] A high-precision continuous optical fiber displacement sensor comprises a displacement beam mounting base and a displacement beam, wherein the displacement beam is connected to the displacement beam mounting base; both ends of the displacement beam mounting base are respectively connected to wire crimping terminals, wherein one wire crimping terminal is connected to an optical cable protection sleeve, and the other wire crimping terminal is connected to a connecting lead; a pull rod outer tube is connected to the displacement beam mounting base on the side close to the connecting lead, a pull rod is built in the pull rod outer tube, one end of the pull rod is connected to a spring, the spring is connected to the displacement beam through a steel wire rope, and the other end of the pull rod is provided with a mounting thread for connecting to a measured object or a displacement beam mounting base of the next optical fiber displacement sensor; a strain grating is provided on the upper surface of the displacement beam, and a temperature grating is provided on the temperature compensation grating pasting wall of the displacement beam.

[0007] Preferably, the displacement beam and the displacement beam mounting base are arranged inside the outer cylinder, and an O-ring is arranged between the displacement beam mounting base and the outer cylinder.

[0008] Preferably, the displacement beam further comprises a displacement beam fixing hole and a wire rope fixing hole, wherein the displacement beam fixing hole is used to be connected to the displacement beam mounting base, and the wire rope fixing hole is used to be connected to the wire rope.

[0009] Preferably, one end of the pull rod outer tube away from the displacement beam mounting base is connected to a pull rod limiting tube.

[0010] Preferably, the strain grating is a femtosecond grating with a wavelength of at least 30 nm.

[0011] Preferably, the connecting lead is an armored optical cable, and the optical cable protective sleeve is a PVC rubber sleeve.

[0012] Preferably, the displacement beam mounting base, outer tube, steel wire rope, pull rod, pull rod outer tube, pull rod limiting tube, and wire crimping terminal are all made of 304 stainless steel, and the displacement beam and spring are all made of 316L stainless steel.

[0013] Preferably, the upper surface of the displacement beam is bonded with a strain grating at a fixed point, and the temperature compensation grating is fully bonded with a temperature grating on the pasting wall.

[0014] The beneficial effect of the utility model is that the high-precision continuous optical fiber displacement sensor, through the structural design of the pull rod, spring, wire rope and displacement beam, when there is a displacement change in the outside world, the deformation of the outside world will be transmitted to the spring through the pull rod, and finally the large displacement of the outside world will be converted into the tension of the spring, which acts on the displacement beam through the wire rope. The tension will cause the displacement beam to produce elastic deformation, and then cause displacement at both ends of the high-strength strain grating, thereby stretching the high-strength strain grating, affecting the wavelength change of the internal light, and finally reflecting the displacement change of the outside world.

[0015] Furthermore, by connecting multiple fiber optic displacement sensors, the high-strength strain grating of each section can reflect the displacement changes of the joint where it is located, which can more accurately monitor the deformation of each joint in the tunnel and provide a large amount of high-precision data for subsequent maintenance and monitoring.

[0016] Among them, the compression of the displacement beam is linearly related to the change in external displacement. The high-strength strain grating uses a high-strength femtosecond grating, the wavelength change can reach more than 30nm, and the resolution accuracy can reach 0.3% 00 , it has sensitive response and high precision, which solves the problems of low precision and inaccurate measurement of existing sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 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:

[0018] Figure 1 It is a structural schematic diagram of the utility model;

[0019] Figure 2 It is a schematic diagram of the internal structure of the utility model;

[0020] Figure 3 It is a structural schematic diagram of the displacement beam of the utility model.

[0021] The markings in the figure are: 1. Optical cable protection sleeve; 2. Wire terminal; 3. Displacement beam mounting base; 4. Strain grating; 5. Displacement beam; 6. Temperature grating; 7. Outer cylinder; 8. Wire rope; 9. O-ring; 10. Spring; 11. Pull rod; 12. Connecting lead; 13. Pull rod outer tube; 14. Pull rod limit tube; 51. Displacement beam fixing hole; 52. Wire rope fixing hole; 53. Temperature compensation grating pasting wall. DETAILED DESCRIPTION

[0022] Embodiment 1

[0023] like Figure 1 As shown, a high-precision continuous optical fiber displacement sensor includes a displacement beam mounting base 3 and a displacement beam 5, wherein the displacement beam 5 is connected to the displacement beam mounting base 3. The two ends of the displacement beam mounting base 3 are respectively connected with crimping terminals 2, one of which is connected to the optical cable protection sleeve 1, and the other crimping terminal 2 is connected to the connecting lead 12.

[0024] The connecting lead 12 includes an external lead and a connecting hose, both of which are used to protect the internal optical fiber, and the connecting hose is also used to connect to the next sensor, such as Figure 1 , Figure 2As shown, the connecting lead 12 is connected to the crimping terminal 2 at the head end of the next sensor. The connecting lead 12 is an armored optical cable, and the optical cable protection sleeve 1 is a PVC rubber sleeve.

[0025] like Figure 2 As shown, a pull rod outer tube 13 is connected to the side of the displacement beam mounting base 3 close to the connecting lead 12, a pull rod 11 is built in the pull rod outer tube 13, one end of the pull rod 11 is connected to a spring 10, the spring 10 is connected to the displacement beam 5 through a steel wire rope 8, the other end of the pull rod 11 is provided with a mounting thread for connecting to the displacement beam mounting base 3 of the object to be measured or the next optical fiber displacement sensor, and a pull rod limit tube 14 is connected to the end of the pull rod outer tube 13 away from the displacement beam mounting base 3, the pull rod limit tube 14 is used to limit the position of the pull rod 11 to avoid exceeding the use range, thereby protecting the sensor.

[0026] like Figure 1 , Figure 2 As shown, the high-precision continuous optical fiber displacement sensor is composed of a plurality of optical fiber displacement sensors connected end to end. When in use, the pull rod 11 of the last sensor in the high-precision continuous optical fiber displacement sensor is connected to the object to be measured through a universal shaft.

[0027] The displacement beam 5 further includes a displacement beam fixing hole 51 and a wire rope fixing hole 52 . The displacement beam fixing hole 51 is used to connect with the displacement beam mounting base 3 , and the wire rope fixing hole 52 is used to connect with the wire rope 8 .

[0028] Furthermore, the upper surface of the displacement beam 5 is provided with a strain grating 4, and the temperature compensation grating pasting wall 53 of the displacement beam 5 is provided with a temperature grating 6, wherein the strain grating 4 is a femtosecond grating with a wavelength of at least 30nm, ensuring that the resolution accuracy of the sensor reaches 0.3% 00 .

[0029] Specifically, the strain grating 4 is mounted on the upper surface of the displacement beam 5 by fixed-point bonding, and the temperature grating 6 is mounted on the temperature compensation grating pasting wall 53 by full bonding. The temperature grating 6 is used to compensate for the deviation of the high-strength strain grating 4 caused by temperature, thereby ensuring the accuracy of sensor measurement.

[0030] When there is a displacement change in the outside world, the deformation of the outside world will be transmitted to the spring 10 through the pull rod 11, and finally the large displacement of the outside world will be converted into the tension of the spring 10, which will act on the displacement beam 5 through the wire rope 8. The tension will cause the displacement beam 5 to produce elastic deformation, and then the two ends of the high-intensity strain grating 4 will be displaced, thereby stretching the high-intensity strain grating 4, affecting the wavelength change of the internal light, and finally reflecting the displacement change of the outside world.

[0031] In addition, the displacement beam 5 and the displacement beam mounting base 3 are arranged inside the outer tube 7, and an O-ring 9 is arranged between the displacement beam mounting base 3 and the outer tube 7. The outer tube 7 protects the internal components, and the O-ring 9 increases the stability between the displacement beam mounting base 3 and the outer tube 7.

[0032] In addition, the displacement beam mounting base 3, outer tube 7, wire rope 8, tie rod 11, tie rod outer tube 13, tie rod limit tube 14, and wire crimping terminal 2 are all made of 304 stainless steel, and the displacement beam 5 and spring 10 are all made of 316L stainless steel. The outer tube 7 made of 304 stainless steel, the tie rod outer tube 13, and the O-ring 9 made of rubber form a closed housing, which overcomes the problems of condensation and electromagnetic interference inside the sensor in humid air, greatly prolongs the service life of the sensor, and improves the reliability of the sensor.

[0033] According to the needs of the site, high-precision continuous optical fiber displacement sensors with different numbers of sections are customized, and each section of the sensor is connected through a connecting lead 12 and a pull rod 11.

[0034] By deploying the continuous optical fiber displacement sensor in the pipe segments and shield joints of the subway tunnel, the deformation of the subway tunnel can be continuously monitored over a large area, and the deformation of the subway tunnel structure can be detected in a timely and accurate manner, providing a large amount of data support for the safety and maintenance of the subway tunnel.

[0035] Working principle: When the high-precision continuous optical fiber displacement sensor is used, it is fixed to the joint of the tunnel through an external clamp, and is fixed to the tunnel wall through the mounting thread on the sensor pull rod 11 of the last section and the universal shaft.

[0036] When there is a displacement change in the outside world, the deformation of the outside world will be transmitted to the spring 10 through the pull rod 11, and finally the large displacement of the outside world will be converted into the tension of the spring 10, which will act on the displacement beam 5 through the wire rope 8. The tension will cause the displacement beam 5 to produce elastic deformation, and then the two ends of the strain grating 4 will be displaced, thereby stretching the strain grating 4, affecting the wavelength change of the internal light, and finally reflecting the displacement change of the outside world.

[0037] By reflecting the displacement changes of the joints where the multi-section strain grating 4 is located, the deformation of each joint in the tunnel can be monitored more accurately, providing a large amount of high-precision data for subsequent maintenance and monitoring.

[0038] The above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above 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 utility model shall be included in the protection scope of the utility model.

Claims

1. A high-precision continuous optical fiber displacement sensor, characterized in that: It comprises a displacement beam mounting base (3) and a displacement beam (5), wherein the displacement beam (5) is connected to the displacement beam mounting base (3); Both ends of the displacement beam mounting base (3) are respectively connected to wire crimping terminals (2), one of the wire crimping terminals (2) is connected to the optical cable protection sleeve (1), and the other wire crimping terminal (2) is connected to the connecting lead (12); A pull rod outer tube (13) is connected to the displacement beam mounting base (3) on one side close to the connecting lead (12), a pull rod (11) is built into the pull rod outer tube (13), one end of the pull rod (11) is connected to a spring (10), the spring (10) is connected to the displacement beam (5) via a steel wire rope (8), and the other end of the pull rod (11) is provided with a mounting thread for connecting to the displacement beam mounting base (3) of the object to be measured or the next optical fiber displacement sensor; The upper surface of the displacement beam (5) is provided with a strain grating (4), and the temperature compensation grating pasting wall (53) of the displacement beam (5) is provided with a temperature grating (6).

2. The high-precision continuous optical fiber displacement sensor according to claim 1, characterized in that: The displacement beam (5) and the displacement beam mounting base (3) are arranged inside the outer cylinder (7), and an O-type sealing ring (9) is arranged between the displacement beam mounting base (3) and the outer cylinder (7).

3. The high-precision continuous optical fiber displacement sensor according to claim 1, characterized in that: The displacement beam (5) further comprises a displacement beam fixing hole (51) and a steel wire rope fixing hole (52); the displacement beam fixing hole (51) is used to connect to the displacement beam mounting base (3), and the steel wire rope fixing hole (52) is used to connect to the steel wire rope (8).

4. The high-precision continuous optical fiber displacement sensor according to claim 1, characterized in that: One end of the pull rod outer tube (13) away from the displacement beam mounting base (3) is connected to a pull rod limiting tube (14).

5. The high-precision continuous optical fiber displacement sensor according to claim 1, characterized in that: The strain grating (4) is a femtosecond grating with a wavelength of at least 30 nm.

6. The high-precision continuous optical fiber displacement sensor according to claim 1, characterized in that: The connecting lead (12) is an armored optical cable, and the optical cable protection sleeve (1) is a PVC rubber sleeve.

7. The high-precision continuous optical fiber displacement sensor according to claim 1, characterized in that: The displacement beam mounting base (3), outer tube (7), steel wire rope (8), pull rod (11), pull rod outer tube (13), pull rod limit tube (14), and wire pressing terminal (2) are all made of 304 stainless steel, and the displacement beam (5) and spring (10) are all made of 316L stainless steel.

8. The high-precision continuous optical fiber displacement sensor according to claim 1, characterized in that: The upper surface of the displacement beam (5) is bonded to the strain grating (4) at a fixed point, and the temperature compensation grating is fully bonded to the temperature grating (6) on the adhesive wall (53).

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