阅读说明：本技术 基于分布式光纤的桥梁动挠度监测方法 (Bridge dynamic deflection monitoring method based on distribution type fiber-optic ) 是由 胡启军 岳杰 何乐平 于 2019-09-30 设计创作，主要内容包括：本发明涉及光纤传感与桥梁监测领域的一种基于分布式光纤的桥梁动挠度监测方法,由外置式光纤传感器、传输光缆、光纤解调仪、监控主机、窄带宽激光光源组成。本发明为解决现有桥梁动挠度监测方法中测量周期长、时效性差、经济效应低、测量速度慢等问题。提供了一种基于分布式光纤的桥梁动挠度监测方法。主要是在桥梁的主梁底部粘结固定外置式光纤传感器,并将外置式光纤传感器用传输光缆与光纤解调仪相连,再将光纤解调仪与监控主机相连。采用干涉型光时域反射技术实时、自动测量桥梁的动挠度。主要适用于中小跨径的梁桥。(The present invention relates to a kind of bridge dynamic deflection monitoring methods based on distribution type fiber-optic of Fibre Optical Sensor and bridge monitoring field, are made of external fibre optical sensor, transmission cable, optical fibre interrogation instrument, monitoring host computer, narrow bandwidth laser light source.The problems such as present invention is measurement period length, poor in timeliness in solution existing highway bridge dynamic deflection monitoring method, economic benefits are low, measuring speed is slow.Provide a kind of bridge dynamic deflection monitoring method based on distribution type fiber-optic.Mainly in the fixed external fibre optical sensor of the girder bottom adhesive of bridge, and external fibre optical sensor is connected with transmission cable with optical fibre interrogation instrument, then optical fibre interrogation instrument is connected with monitoring host computer.Real-time, automatic measurement bridge the dynamic deflection using interference-type optical time domain reflection technology.It is primarily adapted for use in the beam bridge of Mid and minor spans.)

1. the bridge dynamic deflection monitoring method based on distribution type fiber-optic, mainly by external fibre optical sensor (8), transmission cable (9), optical fibre interrogation instrument (10), monitoring host computer (11), narrow bandwidth laser light source (12) composition, it is characterised in that: its monitoring step Are as follows:

A, fixed external fibre optical sensor (8) in the girder of bridge (7) bottom adhesive, and by external fibre optical sensor (8) It is connected with transmission cable (9) with optical fibre interrogation instrument (10), then optical fibre interrogation instrument (10) is connected with monitoring host computer (11)；

B, the back scattering luminous intensity in the optical fiber as caused by deflection of bridge span is demodulated using interference-type optical time domain reflection technology to become Change amount calculates deflection of bridge span, and the amount of deflection change curve of output bridge by monitoring host computer Bridge deflection monitoring software.

2. the bridge dynamic deflection monitoring method according to claim 1 based on distribution type fiber-optic, it is characterised in that: the prison The working principle of deflection monitoring software used in control host (11) is: according to before the bridge deformation demodulated with optical fiber after deformation In behind each position to the knots modification Δ I of Rayleigh scattering luminous intensity_i(x), each position of bridge is calculated using following formula Amount of deflection, and show the amount of deflection change curve of bridge:

In formula, Δ I₁(x)、ΔI₂It (x) is the change before bridge deformation with back scattering luminous intensity in position each in optical fiber after deformation Amount, h are vertical range of the optical fiber to girder axis, C_IεFor the scattered light intensity coefficient of strain.

3. the bridge dynamic deflection monitoring method according to claim 1 based on distribution type fiber-optic, it is characterised in that: described outer Set formula fibre optical sensor (8) manufacture craft are as follows:

A1, sensor fibre (13) are constituted in the polyethylene surrounding layer (6) that bare fibre (5) wraps up one layer of 1mm thickness outside；

A2, laying sensor fibre is alternately repeated in horizontal and vertical direction with serpentine fashion in the U-shaped plastic cement thin plate (1) (13), i.e., first transversely with snakelike laying sensor fibre (13), lateral fiber lengths are 180mm, and longitudinal gap is between optical fiber 15mm, being laid with distance along longitudinal direction is 405mm, then along longitudinal direction with snakelike laying sensor fibre (13), longitudinal fiber lengths are 150mm, longitudinal gap is 15mm between optical fiber, and being transversely laid with distance is 45mm；

A3, the sensor fibre (13) of laying is fixed with seccotine, while is reserved centainly at U-shaped plastic cement thin plate (1) both ends The sensor fibre (13) of length；

A4, U-shaped plastic cement thin plate (1) is filled up with epoxy resin (3)；

A5, it covers to encapsulate on U-shaped plastic cement thin plate (1) with a rectangle plastic cement thin plate (2) and fix；

A6, optical patchcord (4) are welded on reserved sensor fibre (13).

4. the bridge dynamic deflection monitoring method according to claim 1 based on distribution type fiber-optic, it is characterised in that: external The installation method of fibre optical sensor (8) are as follows: external fibre optical sensor (8) is first bonded in bridge main beam (7) bottom with seccotine Portion, then be fixed with screw.

Technical field

The present invention relates to Fibre Optical Sensor and bridge monitoring field, in particular to a kind of bridge moving based on distribution type fiber-optic is scratched Spend monitoring method.

Background technique

Bridge is the important component in modern traffic above-ground, in use due to the effect of external factor, Lateral, longitudinal, vertical deformation (amount of deflection) can occur.Occur not if these deform the excessive each position that can not only make bridge With the damage of degree, reduce the service life of bridge, and will affect the passage of vehicle and pedestrian.So must be to the change of bridge Shape carries out real-time monitoring, and just to the monitoring technology in the field, more stringent requirements are proposed for this.

Traditional deformation monitoring method has the artificial measurement method such as accurate span, traverse survey, the measurement of the level, amesdial. The above method needs a large amount of human and material resources and there is monitoring blind spot, this program for highroad, railroad bridge is multiple Miscellaneous, heavy workload is difficult to quantify, globality poor；Large bridge is needed to set up observation platform, implements traffic control etc., sternly Ghost image rings normal traffic circulation；And measurement period is long, poor in timeliness, not can be carried out real-time monitoring.

Optical fiber sensing technology rises in early 1970s, since it is with small in size, flexible, intrinsic peace Entirely, the advantages that electromagnetism interference, structure are simple, measurement accuracy is high is widely applied to civil engineering, space flight and aviation, power train The fields such as system, medical treatment.Distributed Optical Fiber Sensing Techniques originate from phase late 1970s, are by injecting laser pulse Optical fiber, and its backscatter signals is detected, it realizes to the real-time, accurate of external environment, distributed monitoring.But it is existing Fiber grating sensing technology, Brillouin fiber optic sensing technology there are economic benefits it is low, monitoring velocity is slow the problems such as, it is difficult to realize bridge The dynamic deflection of beam monitors.

Interference-type optical time domain reflection technology is one of Distributed Optical Fiber Sensing Techniques, is by by beam of laser arteries and veins Injection fibre is rushed, and its backward Rayleigh scattering light is detected, to demodulate the variation of phase, intensity, is realized to the external world The monitoring of variation.Optical time domain reflection technology also has measuring speed fast, sensitive other than having the advantages that distributing optical fiber sensing Degree is high, measures distance, adverse environment resistant, non-maintaining feature.Optical time domain reflection technology is at present to be widely used in circumference peace The fields such as anti-monitoring, weak vibration measurement, temperature, but there are no applied in terms of bridge dynamic deflection monitoring.

Summary of the invention

The present invention provides a kind of based on distribution type fiber-optic to solve deficiency existing for existing highway bridge dynamic deflection monitoring method Bridge dynamic deflection monitoring method, the dynamic deflection of bridge during automatic, real-time, quick, accurate and effective monitoring operation, it is ensured that The normal operation of bridge.

The technical solution adopted by the present invention is that: the bridge dynamic deflection monitoring method based on distribution type fiber-optic, mainly by external Formula fibre optical sensor, transmission cable, optical fibre interrogation instrument, monitoring host computer, narrow bandwidth laser light source composition, it is characterised in that: it is supervised Survey step are as follows: a, the fixed external fibre optical sensor of girder bottom adhesive in bridge, and external fibre optical sensor is passed It loses cable (9) to be connected with optical fibre interrogation instrument, then optical fibre interrogation instrument is connected with monitoring host computer.

B, the back scattering light intensity in the optical fiber as caused by deflection of bridge span is demodulated using interference-type optical time domain reflection technology Variable quantity is spent, deflection of bridge span, and the amount of deflection change curve of output bridge are calculated by monitoring host computer Bridge deflection monitoring software.

The working principle of deflection monitoring software used in monitoring host computer is: according to before the bridge deformation demodulated with deformation Afterwards in optical fiber behind each position to the knots modification Δ I of Rayleigh scattering luminous intensity_i(x), to calculate bridge using following formula each The amount of deflection of position, and show the amount of deflection change curve of bridge:

In formula, Δ I₁(x)、ΔI₂(x) for before bridge deformation with back scattering luminous intensity in position each in optical fiber after deformation Knots modification, h are vertical range of the optical fiber to girder axis, C_IεFor the scattered light intensity coefficient of strain.

External fibre optical sensor manufacture craft are as follows:

A1, the polyethylene surrounding layer that one layer of 1mm thickness is wrapped up outside bare fibre constitute sensor fibre；

A2, laying sensor fibre is alternately repeated in horizontal and vertical direction with serpentine fashion in a U-shaped plastic cement thin plate, I.e. first transversely with snakelike laying sensor fibre, lateral fiber lengths are 180mm, and longitudinal gap is 15mm between optical fiber, along vertical It is 405mm to distance is laid with, then along longitudinal direction with snakelike laying sensor fibre, longitudinal fiber lengths are 150mm, longitudinal direction between optical fiber Between be divided into 15mm, transversely be laid with distance be 45mm；

A3, the sensor fibre of laying is fixed with seccotine, while reserves certain length at U-shaped plastic cement thin plate both ends Sensor fibre；

A4, with epoxy fill U-shaped plastic cement thin plate；

A5, fixation is encapsulated on U-shaped plastic cement thin plate with a rectangle plastic cement sheet metal cover；

A6, optical patchcord is welded on reserved sensor fibre.

The installation method of external fibre optical sensor are as follows: external fibre optical sensor is first bonded in bridge master with seccotine Beam bottom portion, then be fixed with screw.

The beneficial effects of the present invention are:

1, in the fixed external fibre optical sensor of the girder bottom adhesive of bridge, and external fibre optical sensor is transmitted Optical cable is connected with optical fibre interrogation instrument, then optical fibre interrogation instrument is connected with monitoring host computer.It is real using interference-type optical time domain reflection technology Monitoring real-time to bridge dynamic deflection, quick, accurate and effective is showed, it is ensured that the normal operation of bridge.

2, using external fibre optical sensor, the globality that the fluting on beam destroys structure is avoided, ensure that sensor The preferable compatibility between bridge, to improve the accuracy of measurement result.Snakelike fiber deployment mode is one Determine the positioning accuracy for improving deflection monitoring in degree, and is exaggerated extraneous disturbance.

Detailed description of the invention

Fig. 1 monitoring system structure diagram

Fig. 2 external optical fibre sensor structure figure

Fig. 3 sensor fibre structure chart

In figure, 1.U shapes offset plate, 2. rectangle plastic plates, 3. epoxy resin, 4. optical patchcords, 5. bare fibres, 6. polyethylene Surrounding layer, 7. bridge girders, 8. external fibre optical sensors, 9. transmission cables, 10. optical fibre interrogation instrument, 11. monitoring host computers, 12. is narrow Bandwidth laser source.13. sensor fibre.

Specific embodiment

The present invention will be further described with reference to the accompanying drawing.

The bridge dynamic deflection monitoring method is mainly by external fibre optical sensor 8, transmission cable 9, optical fibre interrogation instrument 10, prison Control host 11, narrow bandwidth laser light source 12 forms, it is characterised in that: in the fixed external optical fiber of 7 bottom adhesive of girder of bridge Sensor 8, and external fibre optical sensor 8 is connected with transmission cable 9 with optical fibre interrogation instrument 10, then by optical fibre interrogation instrument 10 with Monitoring host computer 11 is connected.Real-time, automatic measurement bridge the dynamic deflection using interference-type optical time domain reflection technology, as shown in Figure 1.

Wherein the working principle of deflection monitoring software used in monitoring host computer is: according to before the bridge deformation demodulated with After deformation in optical fiber behind each position to the knots modification Δ I of Rayleigh scattering luminous intensity_i(x), bridge is calculated using following formula The amount of deflection of each position, and show the amount of deflection change curve of bridge:

In formula, Δ I₁(x)、ΔI₂(x) for before bridge deformation with back scattering luminous intensity in position each in optical fiber after deformation Knots modification, h are vertical range of the optical fiber to girder axis, C_IεFor the scattered light intensity coefficient of strain.

Its Computing Principle is as follows:

Back scattering luminous intensity and strain are linear in optical fiber, as shown in Equation 1,

Δ I=C_IεΔε (1)

In formula (1) Δ I be bridge deformation before with back scattering luminous intensity knots modification in position each in optical fiber after deformation, C_IεFor The scattered light intensity coefficient of strain, Δ ε are strain knots modification.

Vertical deformation is small deformation in bridge, takes one micro- section in overall length of bridge, asks amount of deflection to manage by mechanics of materials integration method By knowing.

Formula (2), (3), ε (x) is the strain value of bridge main beam in (4), and h is vertical range of the optical fiber to girder axis, and ρ is The corresponding radius of curvature of neutral line, d in micro- section_θFor the relative rotation of two sections in micro- section.

Convolution (1), (4), the then sag curve of bridge are as follows:

As shown in Fig. 2, the manufacture craft of external fibre optical sensor 8 is as follows:

A1, laying sensor fibre is alternately repeated in horizontal and vertical direction with serpentine fashion in a U-shaped plastic cement thin plate, I.e. first transversely with snakelike laying sensor fibre, lateral fiber lengths are 180mm, and longitudinal gap is 15mm between optical fiber, along vertical It is 405mm to distance is laid with, then along longitudinal direction with snakelike laying sensor fibre, longitudinal fiber lengths are 150mm, longitudinal direction between optical fiber Between be divided into 15mm, transversely be laid with distance be 45mm；

A2, the sensor fibre of laying is fixed with seccotine, while reserves certain length at U-shaped plastic cement thin plate both ends Sensor fibre；

A3, with epoxy fill U-shaped plastic cement thin plate；

A4, fixation is encapsulated on U-shaped plastic cement thin plate with a rectangle plastic cement sheet metal cover；

A5, optical patchcord is welded on reserved sensor fibre.

In the external fibre optical sensor, two longitudinal fiber segments and a lateral fiber segment form a sensing unit, Make the 1m that reaches of its positioning accuracy, and amplifies power external disturbance.

As shown in figure 3, the production method of sensor fibre 13 is to wrap up the polyethylene outsourcing of one layer of 1mm thickness outside bare fibre 5 Layer 6.Embodiment:

1, process to bare fibre: the polyethylene surrounding layer that one layer of 1mm thickness is wrapped up outside bare fibre constitutes sensor fibre.

2, external fibre optical sensor is made:

A1, laying sensor fibre is alternately repeated in horizontal and vertical direction with serpentine fashion in a U-shaped plastic cement thin plate, I.e. first transversely with snakelike laying sensor fibre, lateral fiber lengths are 180mm, and longitudinal gap is 15mm between optical fiber, along vertical It is 405mm to distance is laid with, then along longitudinal direction with snakelike laying sensor fibre, longitudinal fiber lengths are 150mm, longitudinal direction between optical fiber Between be divided into 15mm, transversely be laid with distance be 45mm；

A2, the sensor fibre of laying is fixed with seccotine, while reserves certain length at U-shaped plastic cement thin plate both ends Sensor fibre；

A3, with epoxy fill U-shaped plastic cement thin plate；

A4, fixation is encapsulated on U-shaped plastic cement thin plate with a rectangle plastic cement sheet metal cover；

A5, optical patchcord is welded on reserved sensor fibre.

3, in the fixed external fibre optical sensor of the girder bottom adhesive of bridge, and external fibre optical sensor is transmitted Optical cable is connected with optical fibre interrogation instrument, then optical fibre interrogation instrument is connected with monitoring host computer.

4, the back scattering light intensity in the optical fiber as caused by deflection of bridge span is demodulated using interference-type optical time domain reflection technology Variable quantity is spent, deflection of bridge span, and the amount of deflection change curve of output bridge are calculated by monitoring host computer Bridge deflection monitoring software.