阅读说明：本技术 一种格构梁形变光纤实时传感监测系统 (Real-time sensing and monitoring system for lattice beam-shaped optical fiber ) 是由 白清 张昆 梁昌硕 靳宝全 高妍 张红娟 王宇 刘昕 于 2021-07-22 设计创作，主要内容包括：本发明一种格构梁形变光纤实时传感监测系统,属于分布式光纤传感技术领域；目的在于解决现有格构梁形变监测方案无法实时精确检测到格构梁梁体变形,无法实时评估边坡状态,对大范围的边坡无法实现有效监测的问题；本发明采用双主干涉光回路、光偏振态控制技术和光强放大技术,利用去斜滤波补偿扫频激光的非线性相位,实现实时准确的格构梁网络监测；同时,本发明给出了具体的传感光纤在格构梁梁体和格构梁网络内部的铺设方法,实现了对边坡格构梁网络的实时准确监测,具有实时性强,测量精准,全天候监测等优点。(The invention discloses a lattice beam deformation optical fiber real-time sensing and monitoring system, belonging to the technical field of distributed optical fiber sensing; the method aims to solve the problems that the deformation of a lattice beam body cannot be accurately detected in real time, the slope state cannot be evaluated in real time and the effective monitoring on a large-scale slope cannot be realized by the conventional lattice beam deformation monitoring scheme; the invention adopts a double-main interference optical loop, a light polarization state control technology and a light intensity amplification technology, utilizes the deskew filtering to compensate the nonlinear phase of the sweep-frequency laser, and realizes real-time and accurate lattice beam network monitoring; meanwhile, the invention provides a specific method for laying the sensing optical fiber in the lattice beam body and the lattice beam network, realizes the real-time and accurate monitoring of the slope lattice beam network, and has the advantages of strong real-time performance, accurate measurement, all-weather monitoring and the like.)

1. The utility model provides a real-time sensing monitoring system of lattice beam shape optical fiber which characterized in that: the device comprises a linear sweep light source output module (35), a double-main interference light loop sensing module (34), an auxiliary interference nonlinear phase acquisition module (36) and a data acquisition processing module (37);

the output end T of the linear sweep light source output module (35) is connected to the input end of the double-main interference light loop sensing module (34) through an optical fiber, and the output end V of the linear sweep light source output module (35) is connected to the input end of the auxiliary interference nonlinear phase acquisition module (36) through an optical fiber;

the output end U of the double-main interference light loop module (34) is connected with the input end X of the data acquisition processing module (37) through an optical fiber, and the output end W of the double-main interference light loop module (34) is connected with the input end Y of the data acquisition processing module (37) through an optical fiber;

and the output end of the auxiliary interference nonlinear phase acquisition module (36) is connected with the input end Z of the data acquisition processing module (37) through an optical fiber.

2. The real-time sensing and monitoring system for the lattice beam-shaped optical fiber as claimed in claim 1, wherein: the double-main interference optical loop sensing module (34) comprises a second optical fiber coupler (4), a third optical fiber coupler (5), a first optical circulator (6), a first polarization controller (7), a transverse sensing optical fiber (8), a fourth optical fiber coupler (9), a second adjustable optical amplifier (10), a seventh optical fiber coupler (19), a second optical circulator (20), a second polarization controller (21), a longitudinal optical fiber (22), an eighth optical fiber coupler (23) and a fourth adjustable optical amplifier (24), and a specific optical path structure is as follows:

the output end C of the second optical fiber coupler (4) is connected with the input end of a third optical fiber coupler (5), the output end E of the third optical fiber coupler (5) is connected with the input end of a first optical circulator (6), the output end A of the first optical circulator (6) is connected with a transverse sensing optical fiber (8), the output end B of the first optical circulator (6) is connected with the input end G of a fourth optical fiber coupler (9), the output end F of the third optical fiber coupler (5) is connected with the input end of a first polarization controller (7), the output end of the first polarization controller (7) is connected with the input end H of the fourth optical fiber coupler (9), the output end of the fourth optical fiber coupler (9) is connected with the input end of a second optical amplifier (10), and the output end of the second optical amplifier (10) is connected with the input end of a first photoelectric detector (11);

the output end D of the second optical fiber coupler (4) is connected with the input end of a seventh optical fiber coupler (19), the output end I of the seventh optical fiber coupler (19) is connected with the input end of a second optical circulator (20), the output end C of the second optical circulator (20) is connected with a longitudinal sensing optical fiber (22), the output end D of the second optical circulator (20) is connected with the input end K of an eighth optical fiber coupler (23), the output end J of the seventh optical fiber coupler (19) is connected with the input end of a second polarization controller (21), the output end of the second polarization controller (21) is connected with the input end L of an eighth optical fiber coupler (23), the output end of the eighth optical fiber coupler (23) is connected with the input end of a fourth dimmable amplifier (24), and the output end of the fourth dimmable amplifier (24) is connected with the input end of a third photoelectric detector (25).

3. The real-time sensing and monitoring system for the lattice beam-shaped optical fiber as claimed in claim 2, wherein: the data acquisition processing module (37) comprises a first photoelectric detector (11), a second photoelectric detector (18) and a third photoelectric detector (25), three paths of optical signals of an output end U and an output end W of the double-main interference optical loop module (34) and an output end of the auxiliary interference nonlinear phase acquisition module (36) are converted into electric signals to be input into the computer (12), the auxiliary interference signals acquired by a port S of the computer (12) are analyzed through a deskew filtering algorithm, the nonlinear phase of the whole optical path system is extracted, transverse and longitudinal beat frequency signals acquired by a port Q and a port R of the computer (12) are subjected to nonlinear phase compensation after the nonlinear phase of the system is extracted, demodulation is completed, and deformation information of the lattice beam network is acquired.

4. The real-time sensing and monitoring system for the lattice beam-shaped optical fiber as claimed in claim 1, wherein: the linear sweep light source output module (35) comprises a linear sweep laser source (1), a first optical fiber coupler (2) and a first adjustable optical amplifier (3), wherein the output end of the linear sweep laser source (1) is connected with the input end of the first optical fiber coupler (2), the output end A of the first optical fiber coupler (2) is connected with the input end of the first adjustable optical amplifier (3), the output end of the first adjustable optical amplifier (3) is connected with the input end of a second optical fiber coupler (4), and the output end B of the first optical fiber coupler (2) is connected with the input end of a fifth optical fiber coupler (13).

5. The system according to claim 4, wherein the real-time sensing and monitoring system comprises: the output optical power ratio of the output end T and the output end V of the linear sweep light source output module (35) is 198: 1.

6. the real-time sensing and monitoring system for the lattice beam-shaped optical fiber as claimed in claim 2, wherein: the splitting ratio of the output end C and the output end D of the second optical fiber coupler (4) is 50: 50.

7. the real-time sensing and monitoring system for the lattice beam-shaped optical fiber as claimed in claim 1, wherein: the auxiliary interference nonlinear phase acquisition module (36) comprises a fifth optical fiber coupler (13), a delay optical fiber (14), a third polarization controller (15), a sixth optical fiber coupler (16) and a third adjustable optical amplifier (17), and the specific optical path structure is as follows:

the output end M of the fifth optical fiber coupler (13) is connected with the input end O of the sixth optical fiber coupler (16) through the delay optical fiber (14), the output end of the sixth optical fiber coupler (16) is connected with the input end of the third adjustable optical amplifier (17), the output end of the third adjustable optical amplifier (17) is connected with the input end Z of the data acquisition processing module (37), the output end N of the fifth optical fiber coupler (13) is connected with the input end of the third polarization controller (15), and the output end of the third polarization controller (15) is connected with the input end P of the sixth optical fiber coupler (16).

Technical Field

The invention discloses a lattice beam deformation optical fiber real-time sensing and monitoring system, and belongs to the technical field of distributed optical fiber sensing real-time monitoring systems.

Background

Slope protection and reinforcement are always an important problem for landslide control and road maintenance in China, and the lattice beam is widely applied as an effective measure for landslide control. The problem of monitoring the deformation of the lattice beam is always the key point of domestic and foreign research, but the existing lattice beam deformation monitoring scheme has the problems of large measurement error of a monitoring system, insufficient measurement real-time performance, complex and unstable system structure, difficulty in maintenance and detection, high cost and the like, and brings great difficulty to the slope protection work. The real-time optical fiber sensing monitoring system for the deformation of the lattice beam is based on a distributed optical fiber sensing technology, and has the characteristics of small size, light weight, corrosion resistance, radiation resistance, electromagnetic interference resistance, convenience in layout and the like. The optical frequency domain reflection technology in the distributed optical fiber sensing technology has the characteristics of high spatial resolution, high real-time performance, high precision and the like, but is limited by the performance of a frequency sweeping laser source, the problem of nonlinearity of frequency sweeping laser exists, great interference is caused to a sensing signal, the signal-to-noise ratio is low, and the measurement precision is reduced due to the unreasonable laying of the sensing optical fiber in practical application.

Aiming at various defects of the current lattice beam deformation monitoring system, the invention provides a lattice beam deformation real-time optical fiber sensing monitoring system which takes an optical frequency domain reflection technology as a core and combines a deskew filtering algorithm, a double-main interference optical loop, a light intensity amplification technology and a light polarization state control technology.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to solve the technical problems that: the improvement of the hardware structure of the lattice beam-shaped optical fiber real-time sensing monitoring system is provided.

In order to solve the technical problems, the invention adopts the technical scheme that: a lattice beam-shaped optical fiber real-time sensing and monitoring system comprises a linear frequency sweeping light source output module, a double-main interference light loop sensing module, an auxiliary interference nonlinear phase acquisition module and a data acquisition processing module;

the output end T of the linear sweep frequency light source output module is connected to the input end of the double-main interference light loop sensing module through an optical fiber, and the output end V of the linear sweep frequency light source output module is connected to the input end of the auxiliary interference nonlinear phase acquisition module through an optical fiber;

the output end U of the double-main interference optical loop module is connected with the input end X of the data acquisition and processing module through an optical fiber, and the output end W of the double-main interference optical loop module is connected with the input end Y of the data acquisition and processing module through an optical fiber;

and the output end of the auxiliary interference nonlinear phase acquisition module is connected with the input end Z of the data acquisition processing module through an optical fiber.

The double-main interference optical loop sensing module comprises a second optical fiber coupler, a third optical fiber coupler, a first optical circulator, a first polarization controller, a transverse sensing optical fiber, a fourth optical fiber coupler, a second adjustable optical amplifier, a seventh optical fiber coupler, a second optical circulator, a second polarization controller, a longitudinal optical fiber, an eighth optical fiber coupler and a fourth adjustable optical amplifier, and the specific optical path structure is as follows:

the output end C of the second optical fiber coupler is connected with the input end of a third optical fiber coupler, the output end E of the third optical fiber coupler is connected with the input end of a first optical circulator, the output end A of the first optical circulator is connected with a transverse sensing optical fiber, the output end B of the first optical circulator is connected with the input end G of a fourth optical fiber coupler, the output end F of the third optical fiber coupler is connected with the input end of a first polarization controller, the output end of the first polarization controller is connected with the input end H of the fourth optical fiber coupler, the output end of the fourth optical fiber coupler is connected with the input end of a second optical amplifier, and the output end of the second optical amplifier is connected with the input end of a first photoelectric detector;

the output end D of the second optical circulator is connected with the input end K of the eighth optical fiber coupler, the output end of the eighth optical fiber coupler is connected with the input end of the fourth adjustable optical amplifier, the output end of the fourth adjustable optical amplifier is connected with the input end of the third photoelectric detector, the output end J of the seventh optical fiber coupler is connected with the input end of the second polarization controller, the output end of the second polarization controller is connected with the input end L of the eighth optical fiber coupler, the output end D of the second optical fiber coupler is connected with the input end of the seventh optical fiber coupler, the output end I of the seventh optical fiber coupler is connected with the input end of the second optical circulator, and the output end C of the second optical circulator is connected with the longitudinal sensing optical fiber.

The data acquisition processing module comprises a first photoelectric detector, a second photoelectric detector, a third photoelectric detector and a computer, three paths of optical signals of an output end U, an output end W and an output end of the auxiliary interference nonlinear phase acquisition module of the double-main interference optical loop module are converted into electric signals to be input into the computer, an auxiliary interference signal acquired by a port S of the computer is analyzed through a deskew filtering algorithm, the nonlinear phase of the whole optical path system is extracted, transverse and longitudinal beat frequency signals acquired by a port Q and a port R of the computer are subjected to nonlinear phase compensation after the nonlinear phase of the system is extracted, demodulation is completed, and deformation information of the lattice beam network is acquired.

The linear sweep light source output module comprises a linear sweep laser source, a first optical fiber coupler and a first adjustable optical amplifier, wherein the output end of the linear sweep laser source is connected with the input end of the first optical fiber coupler, the output end A of the first optical fiber coupler is connected with the input end of the first adjustable optical amplifier, the output end of the first adjustable optical amplifier is connected with the input end of the second optical fiber coupler, and the output end B of the first optical fiber coupler is connected with the input end of the fifth optical fiber coupler.

The output optical power ratio of the output end T and the output end V of the linear sweep light source output module is 198: 1.

the splitting ratio of the output end C and the output end D of the second optical fiber coupler is 50: 50.

the auxiliary interference nonlinear phase acquisition module comprises a fifth optical fiber coupler, a delay optical fiber, a third polarization controller, a sixth optical fiber coupler and a third adjustable optical amplifier, and the specific optical path structure is as follows:

the output end M of the fifth optical fiber coupler is connected with the input end O of the sixth optical fiber coupler through the delay optical fiber, the output end of the sixth optical fiber coupler is connected with the input end of the third adjustable optical amplifier, the output end of the third adjustable optical amplifier is connected with the input end Z of the data acquisition processing module, the output end N of the fifth optical fiber coupler is connected with the input end of the third polarization controller, and the output end of the third polarization controller is connected with the input end P of the sixth optical fiber coupler.

The technical scheme adopted by the invention takes an optical frequency domain reflection technology as a core, and combines a deskew filtering algorithm, a double-main interference optical loop, a light intensity amplification technology and a light polarization state control technology. Compared with the prior art, the invention has the following beneficial effects.

Firstly, in the existing lattice beam deformation monitoring scheme, the real-time monitoring of the easy-to-slide section for 24 hours is difficult to realize, and the effective monitoring is lacked for the side slope protection of hundreds of kilometers or even thousands of kilometers. The invention is based on the distributed optical fiber sensing technology, has the obvious characteristics of being suitable for deformation monitoring with large range, all weather and high real-time performance, and has lower cost and high spatial resolution compared with the existing lattice beam deformation monitoring scheme.

The invention designs a double-main interference optical loop, utilizes a light intensity amplification technology and a light polarization state control technology, combines a deskew filter, improves the signal intensity, compensates the nonlinear phase noise of beat frequency signals in the sensing optical fiber, improves the signal-to-noise ratio and improves the sensitivity to lattice beam deformation.

The invention provides a laying scheme of the sensing optical fiber in the lattice beam body, solves the spatial contradiction between the longitudinal and transverse optical fiber arrangement, and has wide application range and operability.

Drawings

The invention is further described below with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of an optical fiber sensing and monitoring system according to the present invention.

Fig. 2 and fig. 3 are schematic structural diagrams of optical fiber laying of a sensing optical fiber at a cross-shaped part of a lattice beam network provided by the invention.

Fig. 4 is a schematic structural diagram of the sensor fiber laying at the edge of the lattice beam network according to the present invention.

Fig. 5 is a schematic structural diagram of a sensing fiber according to the present invention.

In the figure: 1 is a linear sweep laser source, 2 is a first optical fiber coupler, 3 is a first tunable optical amplifier, 4 is a second optical fiber coupler, 5 is a third optical fiber coupler, 6 is a first optical circulator, 7 is a first polarization controller, 8 is a transverse sensing optical fiber, 9 is a fourth optical fiber coupler, 10 is a second tunable optical amplifier, 11 is a first photodetector, 12 is a computer, 13 is a fifth optical fiber coupler, 14 is a delay optical fiber, 15 is a third polarization controller, 16 is a sixth optical fiber coupler, 17 is a third tunable optical amplifier, 18 is a second photodetector, 19 is a seventh optical fiber coupler, 20 is a second optical circulator, 21 is a second polarization controller, 22 is a longitudinal sensing optical fiber, 23 is an eighth optical fiber coupler, 24 is a fourth tunable optical amplifier, 25 is a third photodetector, 26 is a first optical fiber laying channel, 27 is a second optical fiber laying channel, and 25 is a second optical fiber laying channel, 28 is a third optical fiber laying channel, 29 is a fourth optical fiber laying channel, 30 is a lattice beam concrete material, 31 is a twisted steel, 32 is an optical fiber core, 33 is a flexible cladding, 34 is a double-main interference loop sensing module, 35 is a linear sweep light source output module, 36 is an auxiliary interference nonlinear phase acquisition module, and 37 is a data acquisition processing module.

Detailed Description

As shown in fig. 1 to 5, the lattice beam deformation optical fiber real-time sensing and monitoring system of the present invention includes a linear swept-frequency light source output module 35, a dual main interference optical loop sensing module 34, an auxiliary interference nonlinear phase acquisition module 36, and a data acquisition processing module 37; the double-main interference optical loop sensing module 34 is used for realizing simultaneous sensing and data transmission of longitudinal and transverse strain distribution information of the lattice beam;

the output end T of the linear sweep light source output module 35 is connected to the input end of the dual-main interference light loop sensing module 34 through an optical fiber, and the output end V of the linear sweep light source output module 35 is connected to the input end of the auxiliary interference nonlinear phase acquisition module 36 through an optical fiber;

the output end U of the dual-main interference optical loop module 34 is connected with the input end X of the data acquisition processing module 37 through an optical fiber, and the output end W of the dual-main interference optical loop module 34 is connected with the input end Y of the data acquisition processing module 37 through an optical fiber;

the output end of the auxiliary interference nonlinear phase acquisition module 36 is connected with the input end Z of the data acquisition processing module 37 through an optical fiber.

The double-main interference optical loop sensing module 34 comprises a second optical fiber coupler 4, a third optical fiber coupler 5, a first optical circulator 6, a first polarization controller 7, a transverse sensing optical fiber 8, a fourth optical fiber coupler 9, a second adjustable optical amplifier 10, a seventh optical fiber coupler 19, a second optical circulator 20, a second polarization controller 21, a longitudinal optical fiber 22, an eighth optical fiber coupler 23 and a fourth adjustable optical amplifier 24, and the specific optical path structure is as follows:

an output end C of the second optical fiber coupler 4 is connected with an input end of a third optical fiber coupler 5, an output end E of the third optical fiber coupler 5 is connected with an input end of a first optical circulator 6, an output end A of the first optical circulator 6 is connected with a transverse sensing optical fiber 8, an output end B of the first optical circulator 6 is connected with an input end G of a fourth optical fiber coupler 9, an output end F of the third optical fiber coupler 5 is connected with an input end of a first polarization controller 7, an output end of the first polarization controller 7 is connected with an input end H of the fourth optical fiber coupler 9, an output end of the fourth optical fiber coupler 9 is connected with an input end of a second optical amplifier 10, and an output end of the second optical amplifier 10 is connected with an input end of a first photoelectric detector 11; an output end J of the seventh optical fiber coupler 19 is connected with an input end of the second polarization controller 21, an output end of the second polarization controller 21 is connected with an input end L of the eighth optical fiber coupler 23, an output end D of the second optical fiber coupler 4 is connected with an input end of the seventh optical fiber coupler 19, an output end I of the seventh optical fiber coupler 19 is connected with an input end of the second optical circulator 20, an output end C of the second optical circulator 20 is connected with the longitudinal sensing optical fiber 22, an output end D of the second optical circulator 20 is connected with an input end K of the eighth optical fiber coupler 23, an output end of the eighth optical fiber coupler 23 is connected with an input end of the fourth adjustable optical amplifier 24, and an output end of the fourth adjustable optical amplifier 24 is connected with an input end of the third photoelectric detector 25.

The data acquisition processing module 37 includes a first photodetector 11, a second photodetector 18, a third photodetector 25, and a computer 12, and converts three optical signals at the output end U, the output end W, and the output end of the auxiliary interference nonlinear phase acquisition module 36 of the dual main interference optical loop module 34 into electrical signals to be input to the computer 12, analyzes the auxiliary interference signal acquired at the port S of the computer 12 through a deskew filtering algorithm, extracts the nonlinear phase of the entire optical path system, and performs nonlinear phase compensation on the transverse and longitudinal beat signals acquired at the port Q and the port R of the computer 12 after extracting the nonlinear phase of the system, and then completes demodulation to acquire deformation information of the lattice beam network.

The linear sweep light source output module 35 comprises a linear sweep laser source 1, a first optical fiber coupler 2 and a first adjustable optical amplifier 3, wherein the output end of the linear sweep laser source 1 is connected with the input end of the first optical fiber coupler 2, the output end A of the first optical fiber coupler 2 is connected with the input end of the first adjustable optical amplifier 3, the output end of the first adjustable optical amplifier 3 is connected with the input end of the second optical fiber coupler 4, and the output end B of the first optical fiber coupler 2 is connected with the input end of the fifth optical fiber coupler 13.

The output optical power ratio of the output end T and the output end V of the linear swept-frequency light source output module 35 is 198: 1.

the splitting ratio of the output end C and the output end D of the second optical fiber coupler 4 is 50: 50.

the auxiliary interference nonlinear phase acquisition module 36 includes a fifth optical fiber coupler 13, a delay optical fiber 14, a third polarization controller 15, a sixth optical fiber coupler 16, and a third tunable optical amplifier 17, and the specific optical path structure is as follows:

an output end M of the fifth optical fiber coupler 13 is connected with an input end O of the sixth optical fiber coupler 16 through the delay optical fiber 14, an output end of the sixth optical fiber coupler 16 is connected with an input end of the third adjustable optical amplifier 17, an output end of the third adjustable optical amplifier 17 is connected with an input end Z of the data acquisition processing module 37, an output end N of the fifth optical fiber coupler 13 is connected with an input end of the third polarization controller 15, and an output end of the third polarization controller 15 is connected with an input end P of the sixth optical fiber coupler 16.

The invention provides a lattice beam deformation real-time optical fiber sensing monitoring system based on an optical frequency domain reflection technology, which comprises a linear frequency sweeping laser source 1, a first optical fiber coupler 2, a first adjustable optical amplifier 3, a second optical fiber coupler 4, a third optical fiber coupler 5, a first optical circulator 6, a first polarization controller 7, a transverse sensing optical fiber 8, a fourth optical fiber coupler 9, a second adjustable optical amplifier 10, a first photoelectric detector 11, a computer 12, a fifth optical fiber coupler 13, a delay optical fiber 14, a third polarization controller 15, a sixth optical fiber coupler 16, a third adjustable optical amplifier 17, a second photoelectric detector 18, a seventh optical fiber coupler 19, a second optical circulator 20, a second polarization controller 21, a longitudinal sensing optical fiber 22, an eighth optical fiber coupler 23, a fourth adjustable optical amplifier 24 and a third photoelectric detector 25; fig. 1 is a schematic structural diagram of a lattice beam-shaped optical fiber real-time sensing and monitoring system according to the present invention.

The linear sweep laser source 1 emits linear sweep laser with a sweep range of 1548nm to 1558nm, the sweep laser enters the input end of the first optical fiber coupler 2, the first optical fiber coupler 2 divides the sweep laser into two beams, and the output end a of the first optical fiber coupler 2 outputs sweep light with 99% of optical power. The output end B of the first optical fiber coupler 2 outputs frequency-swept light with the optical power accounting for 1 percent; the sweep frequency light output by the output end A of the first optical fiber coupler 2 passes through the first adjustable optical amplifier 3, the optical power of the sweep frequency light is amplified to be 2 times of the original optical power, then the sweep frequency light enters the input end of the second optical fiber coupler 4 and is divided into two paths, the optical power ratio is 50%, one path is output to the input end of the third optical fiber coupler 5 from the output end C of the second optical fiber coupler 4, and the other path is output to the input end of the seventh optical fiber coupler 19 from the output end D of the second optical fiber coupler 4; the sweep light input into the third optical fiber coupler 5 is divided into two beams, wherein the output end E of the third optical fiber coupler 5 outputs sweep light with the optical power proportion of 99%, and the output end F outputs sweep light with the optical power proportion of 1%; the swept-frequency light output by the output end E of the third optical fiber coupler 5 enters an input port of the first optical circulator 6, enters the transverse sensing optical fiber 8 from an A port of the first optical circulator 6, the Rayleigh scattered light returned by the transverse sensing optical fiber 8 is output from a B port of the first optical circulator 6 and enters the fourth optical fiber coupler 9 through an input end G of the fourth optical fiber coupler 9, and the swept-frequency light output by the output end F of the third optical fiber coupler 5 enters the fourth optical fiber coupler 9 through an input end H of the fourth optical fiber coupler 9 after the polarization state is adjusted by the first polarization controller 7 and is coupled with the Rayleigh scattered light entering from the input end G of the fourth optical fiber coupler 9; the coupled light output from the output end of the fourth optical fiber coupler 9 enters the first photodetector 11 through the second adjustable optical amplifier 10 to complete beat frequency interference, and is converted into an electrical signal, and the electrical signal is input into a port Q of the computer 12 to complete analysis processing.

The swept-frequency light input into the seventh optical fiber coupler 19 is divided into two beams, wherein the output end I of the seventh optical fiber coupler 19 outputs swept-frequency light with the optical power proportion of 99%, and the output end J outputs swept-frequency light with the optical power proportion of 1%; the swept-frequency light output from the output end I of the seventh optical fiber coupler 19 enters the input port of the second optical circulator 20, enters the longitudinal sensing optical fiber 22 from the port C of the second optical circulator 20, the rayleigh scattered light returned by the longitudinal sensing optical fiber 22 is output from the output end D of the second optical circulator 20, and enters the eighth optical fiber coupler 23 through the input end K of the eighth optical fiber coupler 23, and the swept-frequency light output from the output end J of the seventh optical fiber coupler 19 enters the eighth optical fiber coupler 23 through the input end L of the eighth optical fiber coupler 23 after the polarization state is adjusted by the second polarization controller 21, and is coupled with the rayleigh scattered light entering from the input end K of the eighth optical fiber coupler 23; the coupled light output from the output end of the eighth optical fiber coupler 23 enters the third photodetector 25 through the fourth tunable optical amplifier 24 to complete beat frequency interference, and is converted into an electrical signal, which is input to the port R of the computer 12 to complete analysis processing.

The sweep light output from the output end B of the first optical fiber coupler 2 enters the fifth optical fiber coupler 13 and is divided into two beams, wherein the sweep light with the output end M of the fifth optical fiber coupler 13 having the output optical power ratio of 99% enters the input end O of the sixth optical fiber coupler 16 through the delay optical fiber 14, the sweep light with the output end N of the fifth optical fiber coupler 13 having the output optical power ratio of 1% enters the input end P of the sixth optical fiber coupler 16 after the polarization state is adjusted by the third polarization controller 15 and is coupled with the sweep light entering from the input end O of the sixth optical fiber coupler 16, the coupled sweep light enters the third tunable optical amplifier 17 for optical power amplification, then enters the second optical detector 18 for beat frequency interference, is converted into an electrical signal, and is input into the computer through the port S of the computer 12.

After the three signals are input into the computer, the auxiliary interference signal collected by the port S of the computer 12 is analyzed through a deskew filtering algorithm, and the nonlinear phase of the whole optical path system is extracted. After the nonlinear phase of the system is extracted, nonlinear phase compensation is carried out on transverse and longitudinal beat frequency signals collected by a port Q and a port R of the computer 12, demodulation is completed, and deformation information of the lattice beam network is obtained. Therefore, the real-time sensing monitoring of the deformation of the lattice beam is achieved.

Fig. 2 and 3 are structural diagrams of optical fiber laying at a cross part of a lattice beam network according to the invention, and fig. 4 is a structural diagram of optical fiber laying at an edge of the lattice beam network according to the invention, and the structural diagram includes a transverse sensing optical fiber 8, a longitudinal sensing optical fiber 22, a first optical fiber laying channel 26, a second optical fiber laying channel 27, a third optical fiber laying channel 28, a fourth optical fiber laying channel 29, a lattice beam concrete material 30, and a twisted steel 31.

During specific laying, the transverse sensing optical fiber 8 is laid in the second optical fiber laying channel 27, the longitudinal sensing optical fiber 22 is laid in the third optical fiber laying channel 28, the inner diameter of the optical fiber laying channel is larger than the outer diameter of the optical fiber, the longitudinal sensing optical fiber 22 and the transverse sensing optical fiber 8 are arranged in the respective channels, gaps between the optical fibers and the laying channel are filled with polyurethane materials, and the rest can be poured with concrete materials according to the lattice beam construction scheme.

During specific laying, when the longitudinal sensing optical fiber 22 is laid to the lattice beam edge beam body along the third optical fiber laying channel 28, if steering is needed, the longitudinal sensing optical fiber 22 can be bent and turned into the first optical fiber laying channel 26 according to specific situations on site. Similarly, the transverse sensing fiber 8 can be switched from the second fiber laying channel 27 to the fourth fiber laying channel 29 at the junction of the cross beam and the longitudinal beam according to the field requirement. In a lattice beam body, the first fibre routing channel 26 is at the same elevation as the third fibre routing channel 28, and the second fibre routing channel 27 is at another elevation as the fourth fibre routing channel 29, so that the sensing fibres complete the turn at the beam junction. Direct physical contact of the transverse sensing fiber 8 and the longitudinal sensing fiber 22 within the beam body is avoided. The third fiber-routing channel 28 and the fourth fiber-routing channel 29 in the longitudinal lattice beam body are at different heights within the beam body. The first fiber-routing channel 26 and the second fiber-routing channel 27 in the transverse lattice beam body are at different heights within the beam body.

Fig. 5 is a schematic structural diagram of a sensing optical fiber, which includes an optical fiber core 32 and a flexible cladding 33.

The method is mainly characterized in that an optical frequency domain reflection technology is taken as a core, a deskew filtering algorithm, a double-main interference optical loop and a light intensity amplification technology are combined, 24-hour all-weather uninterrupted monitoring is realized on the lattice beam, any deformation information of the lattice beam is obtained in real time, the integral state of the side slope is judged, early warning is realized, and meanwhile, a laying scheme of the sensing optical fiber in the construction process is provided. The invention provides a laying scheme of the sensing optical fiber in the lattice beam body, solves the spatial contradiction between the longitudinal and transverse optical fiber arrangement, and has wide application range and operability.

It should be noted that, regarding the specific structure of the present invention, the connection relationship between the modules adopted in the present invention is determined and can be realized, except for the specific description in the embodiment, the specific connection relationship can bring the corresponding technical effect, and the technical problem proposed by the present invention is solved on the premise of not depending on the execution of the corresponding software program.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.