CN115389066A - A Bridge Health Monitoring System Based on Distributed Fiber Bragg Grating Sensing - Google Patents

Abstract

The invention relates to a bridge health monitoring system based on distributed fiber bragg grating sensing, which comprises a sensor system, a data processing system and a data processing system, wherein the sensor system is used for monitoring stress and strain reactions of a bridge under the actions of temperature, uneven settlement and load, and simultaneously providing a mode sample and original data of structure inversion analysis for the system; the data transmission and processing system is used for preprocessing the bridge monitoring and measuring information by the sensor system to form a data file, and transmitting the data file to the intelligent management system through the optical fiber modem and the optical cable; the structure analysis and evaluation system is developed and constructed by a road network operation monitoring subsystem of the intelligent management system and mainly analyzes and evaluates monitoring results. The system can accurately measure the information of the girder stress, the expansion joint displacement, the linear change of the girder deflection, the stress of the prestressed steel beam and the like of each point along the optical fiber, greatly reduces the acquisition cost of unit information, can comprehensively master the slight change of the whole and local structures of the bridge, and accurately judges the health condition of the bridge body.

Description

A Bridge Health Monitoring System Based on Distributed Fiber Bragg Grating Sensing

technical field

The invention relates to the technical field of bridge structure health monitoring, in particular to a bridge health monitoring system based on distributed fiber grating sensing.

Background technique

Due to the influence of various factors during the use of the bridge, various parts of the structure will be damaged and deteriorated to varying degrees. These damages must be monitored and repaired, otherwise it will affect driving safety and shorten the life of the bridge, and even cause catastrophic accidents due to sudden damage and collapse of the bridge. Therefore, higher sensing and safety monitoring technologies in this field are proposed requirements. At present, the mechanical sensing technology widely used in bridge monitoring is simple and practical, but this technology is not easy to realize automatic data collection, and cannot meet the needs of real-time monitoring of disasters and accidents; the electrical sensing technology widely used in engineering is mainly resistance type, piezoelectric type, vibrating wire type, etc., because the electric sensor is an active device, its long-term stability is poor, susceptible to electromagnetic interference, complex networking, short signal transmission distance and other disadvantages not only affect the accuracy and stability of monitoring results In addition, additional signal transmission equipment is required, which increases the complexity of the system; the existing automatic detection technology has been widely used in practical safety monitoring, such as wireless sensors and sensor networks, GPS, DC resistivity method, Measurement techniques such as microseismic monitoring, but these techniques also have some disadvantages, such as their susceptibility to environmental noise interference.

Compared with traditional mechanical and electrical sensing and monitoring technologies, the advantages of optical fiber sensing technology include anti-electromagnetic interference, strong waterproof performance, small size, light weight, easy to embed in materials or structures for non-destructive testing, and wide dynamic range. , high sensitivity, long distance transmission of sensing information, flexible and simple packaging process, large-scale networking through composite technology, etc.

Contents of the invention

The purpose of the present invention is to provide a bridge health monitoring system based on distributed fiber grating sensing in order to solve the above problems, so as to realize a long-distance, high-precision, anti-electromagnetic interference, and dynamic monitoring network for bridges.

In order to achieve the above object, the present invention is achieved through the following technical solutions: a bridge health monitoring system based on distributed optical fiber grating sensing, which includes a sensor system for monitoring the health of the bridge under temperature, uneven settlement and load Stress and strain response, solve the problem of effect monitoring in reliability assessment and monitor the static position and static displacement of each part of the bridge to ensure the normal usability of the structure during the service period, and also provide model samples and structural inversion analysis for the system the original data;

The data transmission and processing system preprocesses the bridge monitoring measurement information by the sensor system and forms a data file, which is transmitted to the intelligent management system through an optical fiber modem and optical cable;

The structural analysis and evaluation system is a PC application platform developed and constructed by the road network operation monitoring subsystem of the smart management system, which mainly analyzes and evaluates the monitoring results;

The monitoring measurement information includes the stress of the main girder of the monitored bridge, the displacement of the expansion joint, the linear change of the deflection of the main girder, and the stress of the prestressed steel beam;

To monitor the stress of the main girder of the monitored bridge, fiber grating embedded strain gauges, fiber grating steel bar stress gauges and fiber grating surface strain gauges are used for stress detection;

To monitor the expansion joint displacement of the monitored bridge, a fiber grating displacement meter is selected as a monitoring instrument;

To monitor the linear change of the main girder deflection of the monitored bridge, a fiber grating static level is selected as the monitoring instrument;

For monitoring the stress of the prestressed steel strands outside the monitored bridge, a fiber grating anchor cable strain gauge is selected as the monitoring instrument.

Further, the fiber grating embedded strain gauge, the fiber grating steel bar stress gauge, the fiber grating surface strain gauge, the fiber grating displacement gauge, the fiber grating static level and the fiber grating anchor cable stress gauge adopt a distributed sensing fiber Sensing optical fiber; the layout of the sensing optical fiber can be pre-embedded or laid. When pre-embedded, it can be directly poured into the concrete of the bridge component. When laying, it can be directly pasted on the surface of the structure. The sensing optical fiber can be realized by laying a straight line or a mesh Two-dimensional or three-dimensional monitoring of bridges.

Further, when monitoring the stress of the main girder of the bridge to be monitored, the fiber grating embedded strain gauge should be bound to the steel skeleton before the lining concrete is poured. Fix the fiber grating embedded strain gauge to the steel bar, use the cable tie to fix the strain gauge lead wire to the steel bar and lead it out along the steel bar, and the bend needs to be guided with a bending radius greater than 5cm; the fiber grating steel bar stress gauge adopts the field welding method For installation, fix the fiber grating steel bar stress gauge directly below the main bar to avoid vibration damage during concrete pouring. Use cable ties to fix the fiber grating steel bar stress gauge lead to the steel bar and lead it out along the steel bar. Bending radius lead out, all single-point sensors are lead out in parallel with double-ended leads.

Furthermore, when monitoring the displacement of the expansion joint of the bridge to be monitored, first use a fiber grating displacement meter with a universal joint and a fixing bolt to measure the installation hole position on both sides of the gap, drill the hole to install the fixture, and install the sensor to the Fixture, and pay attention to adjust its position and height, fix one side of the displacement meter, give a certain tensile displacement, and fix the other side of the displacement meter.

Further, when monitoring the linear change of the main girder deflection of the bridge to be monitored, a water tank is placed at the position of the main girder of the bridge, and fiber grating static levels are arranged at intervals. Waterway system; bridge deflection changes, affected by the pressure generated by the water level difference in the fiber grating static level, the wavelength of the fiber grating changes, and then combined with the factory calibration parameters of the fiber grating static level, the measured wavelength of the fiber grating can be changed The data is converted into the vertical displacement, that is, the deflection value of the bridge. At the same time, the linear change monitoring of the bridge deflection is installed on the measuring pier. The fiber grating static level is installed on the measuring pier with the same elevation. They are connected in series in sequence, and a fiber grating static level is arranged at the reference point as a reference for settlement, and the rest of the fiber grating static levels are installed at the design settlement monitoring position.

Furthermore, when monitoring the prestressed steel beam stress of the external cable of the monitored bridge, a typical prestressed steel beam is selected for monitoring, and the fiber grating anchor cable dynamometer is used to measure the main parameters of the external cable diameter and anchoring force on site. Customized processing, the fiber grating anchor cable dynamometer is added between the anchor cable seat and the anchor cable head, and the fiber grating anchor cable dynamometer is used to detect the tension pressure of the anchor cable in real time.

In particular, after all optical fiber sensor components are laid out, multi-core communication optical cables are used to connect in series with redundant optical fiber lead lines, and introduced into the established monitoring station through protective trenches, and finally all optical path signals are collected in the monitoring station. The system is centralized Monitoring, the network control of the overall monitoring unit, cooperates with the development of related software systems to carry out automatic measurement, storage and analysis. Through the wireless transmission network and client software, real-time online monitoring and monitoring results can be viewed, and the purpose of automatic monitoring is finally achieved.

Compared with the prior art, the beneficial effects of the present invention are reflected in:

The sensor of the invention uses optical signals as the carrier, has the characteristics of anti-electromagnetic interference, waterproof, high temperature resistance, etc., and has better durability than metal sensors; the optical fiber sensor is small in size, light in weight, and easy to lay; it can realize long-distance, All-round monitoring; this system can accurately measure the main girder stress, expansion joint displacement, main girder deflection linear change, prestressed steel beam stress and other information at various points along the optical fiber, which greatly reduces the cost of unit information acquisition, and can fully grasp the bridge Subtle changes in the overall and local structure, and accurately judge the health of the beam.

Description of drawings

Figure 1 is a schematic diagram of a fiber grating sensing system;

Fig. 2 is the sensor arrangement diagram when the main girder stress of the monitored bridge is monitored by the present invention;

Fig. 3 is the sensor arrangement diagram when the present invention monitors the expansion joint displacement of the monitored bridge (the * area is the sensor arrangement position);

Fig. 4 is the sensor layout diagram when the present invention monitors the linear variation of the main girder deflection of the monitored bridge;

Fig. 5 is a sensor arrangement diagram of the present invention when monitoring the prestressed steel tendon stress of the external cables of the monitored bridge.

Detailed ways

The present invention will be described in further detail below in conjunction with the embodiments in the accompanying drawings, but this does not constitute any limitation to the present invention.

The invention aims to realize long-distance, high-precision, anti-electromagnetic interference, and dynamic monitoring network for bridges through distributed fiber grating sensing;

Referring to Figure 1, the distributed fiber Bragg grating sensing technology (FBG) mainly realizes various parameters of the measured object by packaging the fiber Bragg grating strain gauge into a variety of different types of fiber grating sensors, and installing them on the measured object. Measurement. Distributed Fiber Bragg Grating (FBG) sensing technology mainly realizes wireless automatic real-time online monitoring. Fiber Bragg Grating (FBG) sensors are formed by changing the refractive index of the core region of an optical fiber to produce a small periodic modulation. When the temperature or stress changes, the optical fiber produces axial strain, which makes the grating period larger, while the fiber core and cladding radii become smaller, and the refractive index of the fiber is changed through the photoelastic effect, thereby causing the grating wavelength shift. Using the linear relationship between the strain and the wavelength offset of the grating, the strain of the measured structure is obtained by calculation. The FBG is formed by the periodic change of the refractive index of the fiber core along the fiber axis. When the incident laser wavelength and the period of the FBG satisfy Under the following conditions, the grating will reflect the laser light. It can be seen from the following formula that the wavelength reflected by the FBG is related to the grating spacing and the refractive index of the fiber. When the fiber undergoes axial deformation and temperature changes, the grid spacing and refractive index will drift, and the reflected wavelength will also drift accordingly, that is, By measuring the drift, the deformation or temperature change of the fiber can be obtained:

表示FBG反射的波长，

表示光纤折射率，

表示栅格间距。由实验研究，应变和温度均与中心波长

存在很好的线性关系，且相互独立，其关联公式下式所示In the formula,

Indicates the wavelength reflected by the FBG,

is the fiber refractive index,

Indicates grid spacing. From experimental studies, both strain and temperature are related to the central wavelength

There is a very good linear relationship, and they are independent of each other, and the correlation formula is shown in the following formula

为光纤光栅应变灵敏系数，

为光纤光栅的温度灵敏度系数，

为温度变化值，ε为应变，因此FBG能够对材料的微变形进行精确测量，为此将FBG封装到附着到弹性元件上即可封装成压力、位移、倾斜及应力等传感器，实现跟多变量传感测试。In the formula,

FBG strain sensitivity coefficient,

is the temperature sensitivity coefficient of the fiber grating,

is the temperature change value, and ε is the strain, so FBG can accurately measure the micro-deformation of the material. For this reason, the FBG can be packaged and attached to the elastic element to be packaged into sensors such as pressure, displacement, tilt and stress, etc., to achieve multi-variable Sensing test.

Based on the principle that FBG can accurately measure the micro-deformation of materials, this invention proposes a bridge health monitoring system based on distributed fiber Bragg grating sensing, which includes a sensor system for monitoring bridges under temperature, uneven settlement and loads It solves the problem of effect monitoring in reliability assessment and monitors the static position and static displacement of various parts of the bridge to ensure the normal usability of the structure during its service life. It also provides model samples and structural inversion for the system the raw data analyzed;

The data transmission and processing system preprocesses the bridge monitoring measurement information by the sensor system and forms a data file, which is transmitted to the intelligent management system through an optical fiber modem and optical cable;

The structural analysis and evaluation system is a PC application platform developed and constructed by the road network operation monitoring subsystem of the smart management system, which mainly analyzes and evaluates the monitoring results;

The monitoring measurement information includes the main girder stress of the monitored bridge, the displacement of the expansion joint, the linear change of the main girder deflection, and the stress of the prestressed steel bundle. The sensing fibers used by all optical fiber sensors are distributed sensing fibers; the sensing fibers The layout methods include pre-embedding or laying. When pre-embedding, it can be directly poured into the concrete of the bridge component. When laying, it can be directly pasted on the surface of the structure. The sensing optical fiber can be used for two-dimensional or three-dimensional monitoring of the bridge through straight line or mesh layout. ; After all the optical fiber sensor devices are laid out, use the multi-core communication optical cable to connect in series with the redundant optical fiber lead lines, and introduce them into the established monitoring station through the protective groove, and finally realize the data collection of all optical path signals in the monitoring station, and the system will be monitored centrally. The networked control of the overall monitoring unit cooperates with the development of related software systems to perform automatic measurement, storage and analysis. Through the wireless transmission network and client software, real-time online monitoring and monitoring results can be viewed, and the purpose of automatic monitoring is finally achieved.

Referring to Figure 2 (sensor arrangement when monitoring the main girder stress of the monitored bridge), stress is the most important expression of the local response of the bridge in operation, and it is the most unfavorable section of the bridge under the action of live load during the operation period. Stress monitoring is carried out in the parts where the disease develops rapidly, and the stress of the main girder of the monitored bridge is monitored. When the beam stress is monitored, considering the complexity of the upper span of the Changhe Expressway and the characteristics of the bridge, 5 sections of the (45+80+45)m prestressed concrete variable-section continuous beam bridge and 3 holes of the small pile number approach bridge are selected. There are 3 sections of the 35-meter simply supported and then continuous prestressed concrete continuous small box girder, a total of 8 monitoring sections for monitoring, of which 5 sections of (45+80+45)m prestressed concrete variable section continuous beam bridge are single Box single room section, each section has 8 sensors, a total of 16 on the left and right sides, a total of 80 sensors; small pile number approach bridge with 3 holes and a 35-meter continuous prestressed concrete continuous small box girder section of 3 sections, 4 small box girder sections are arranged horizontally, with 8 sensors in each section, a total of 16 on the left and right sides, and a total of 48 sensors; a total of 128 sensors on 8 sections.

Fiber Bragg grating embedded strain gauges should be bound to the steel frame before the lining concrete is poured. When installing, the axial direction of the sensor must be parallel to the ring direction of the lining. Fix the lead wire of the strain gauge to the steel bar and lead it out along the steel bar. The bend should be led with a bending radius greater than 5cm; the fiber grating steel bar stress gauge is installed by field welding, and the fiber grating steel bar stress gauge is fixed at the position directly below the main bar to avoid When the concrete is poured, it will be damaged by vibration. Use cable ties to fix the lead wire of the fiber grating steel bar stress gauge to the steel bar and lead it out along the steel bar. The bend needs to be led out with a bending radius greater than 5cm. All single-point sensors use parallel double-ended leads. lead out.

Referring to Figure 3 (the arrangement of sensors when monitoring the displacement of the expansion joints of the monitored bridge), the displacement monitoring can observe whether the beam body has lateral or longitudinal slippage relative to the support, and the displacement of the expansion joints between the beam bodies. For monitoring the expansion joint displacement of the monitored bridge, the fiber grating displacement meter is selected as the monitoring instrument, and 4 positions such as 0# abutment, 3# abutment, 6# abutment, and 9# abutment are selected as monitoring sections, and 2 abutments are arranged for each section. Longitudinal displacement sensor and 2 lateral displacement sensors, a total of 16 displacement sensors are arranged. When monitoring the displacement of the expansion joint of the bridge to be monitored, the optical fiber grating displacement meter with universal joint and fixing bolt is used to measure the displacement on both sides of the gap. Install the hole position, drill holes to install the fixture, install the sensor to the fixture, and pay attention to adjust its position and height, fix one side of the displacement meter, give a certain tensile displacement, and fix the other side of the displacement meter;

Referring to Figure 4 (the arrangement of sensors when monitoring the linear variation of the main girder deflection of the monitored bridge), the main girder deflection monitoring can intuitively grasp the deflection linearity of the bridge, and other monitoring items such as stress monitoring can be used to analyze the impact on the bridge. Factors affecting the deflection; to monitor the linear change of the main girder deflection of the monitored bridge, the fiber grating static level is selected as the monitoring instrument, the No. Field conditions adjustment), plus a total of 8 static levels at the base point. When monitoring the linear change of the main girder deflection of the bridge being monitored, a water tank is placed at the position of the main girder of the bridge, and fiber grating static levels are arranged at intervals. The water tank and the Fiber Bragg grating static levels are connected in series through waterways to form the same waterway system; when bridge deflection changes, affected by the pressure generated by the water level difference in fiber grating static levels, the wavelength of fiber gratings changes, and then combined with fiber grating static levels The factory calibration parameters can convert the measured fiber grating wavelength change data into the vertical displacement, that is, the deflection value of the bridge. At the same time, the linear change monitoring of the bridge deflection is installed on the measuring pier, and the fiber grating static level is installed at the same elevation. On the pier, connect the reference water tank and the static level of the fiber grating in series in sequence, and arrange a static level of the fiber grating at the reference point as the reference of the settlement, and install the rest of the static level of the fiber grating at the design settlement monitoring position.

Referring to Figure 5 (the sensor arrangement when monitoring the prestressed steel tendon stress of the external cable of the monitored bridge), the accuracy of the tension of the prestressed steel tendon bearing the horizontal thrust of the external cable is related to the arch rib, the internal force of the main girder, and the alignment and its own security. Therefore, it is necessary to monitor the tension of the extracorporeal cable. Realize early warning of external cable force through monitoring, and carry out human intervention control; monitor the prestressed steel beam stress monitoring of the external cable of the monitored bridge and select the fiber grating anchor cable stress gauge as the monitoring instrument; in the external cable of the monitored bridge When monitoring the stress of prestressed steel beams, a typical prestressed steel beam is selected for monitoring, and the fiber grating anchor cable dynamometer is customized according to the main parameters of the external cable diameter and anchoring force on site, and the fiber grating anchor cable dynamometer is added It is arranged between the anchor cable seat and the anchor cable head, and uses a fiber grating anchor cable dynamometer to detect the tension pressure of the anchor cable in real time.

In addition, NZS-FBG wireless fiber grating demodulator can be used for fiber optic modems. It has a built-in fast tunable laser light source module. By changing the output wavelength of the tunable light source, the central wavelength of the FBG sensor can be calculated. The client software is based on the wavelength characteristics of the sensor. The parameters are used to calculate the physical value of the fiber grating sensor. This product can be used for long-term on-site measurement, and it is also convenient for secondary development of integrated systems. Multiple sensor channels enable simultaneous demodulation of sensors on multiple fibers or channel analysis. The product is highly integrated wireless transmission module, according to the site environment and data transmission conditions, it uses wireless communication to transmit all the data obtained to the client software test system for monitoring and analysis.

The client software module is divided into a project overview and a sub-item monitoring content menu. The project overview provides users with project monitoring content information, overall layout information, and alarm statistics. The sub-item menu displays the sensor layout point information of each monitoring content, updates the monitoring data in real time and displays the measurement status of the sensor.

The above examples are preferred implementations of the present invention, and are only used to illustrate the present invention conveniently, and are not intended to limit the present invention in any form. Anyone with ordinary knowledge in the technical field, if they do not depart from the present invention, Within the scope of the technical features, the equivalent embodiments that utilize the technical content disclosed in the present invention to make partial changes or modifications without departing from the technical features of the present invention still belong to the scope of the technical features of the present invention.

Claims (7)

1. A bridge health monitoring system based on distributed fiber grating sensing is characterized in that: the system comprises a sensor system, a data acquisition system and a data processing system, wherein the sensor system is used for monitoring stress and strain reactions of a bridge under the action of temperature, differential settlement and load, solving the problem of effect monitoring in reliability evaluation and monitoring the static position and static displacement of each part of the bridge so as to ensure the normal usability of a structure in a service life and simultaneously providing a mode sample and original data of structure inversion analysis for the system;

the data transmission and processing system is used for preprocessing the bridge monitoring measurement information by the sensor system to form a data file, and transmitting the data file to the intelligent management system through the optical fiber modem and the optical cable;

the structure analysis and evaluation system is a PC application platform, is developed and constructed by a road network operation monitoring subsystem of the intelligent management system and mainly analyzes and evaluates monitoring results;

the monitoring and measuring information comprises girder stress, expansion joint displacement, girder deflection linear change and prestressed steel beam stress of the monitored bridge;

the stress of the main beam of the monitored bridge is detected by a fiber grating embedded strain meter, a fiber grating steel bar stress meter and a fiber grating surface strain meter;

the expansion joint displacement of the monitored bridge selects a fiber bragg grating displacement meter as a monitoring instrument;

the linear change of the deflection of the main beam of the monitored bridge selects a fiber grating static level gauge as a monitoring instrument;

and selecting a fiber bragg grating anchor cable stress meter as a monitoring instrument for monitoring the stress of the prestressed steel beam of the external cable of the monitored bridge.

2. The bridge health monitoring system based on distributed fiber grating sensing of claim 1, wherein: sensing optical fibers adopted by the fiber grating embedded type strain meter, the fiber grating reinforcement stress meter, the fiber grating surface strain meter, the fiber grating displacement meter, the fiber grating static level meter and the fiber grating anchor cable stress meter are distributed sensing optical fibers; the sensing optical fibers are arranged in a pre-buried or laid mode, can be directly poured into concrete of a bridge member during pre-burying, can be directly adhered to the surface of a structure during laying, and are arranged in a straight line or a net shape to realize two-dimensional or three-dimensional monitoring on the bridge.

3. The bridge health monitoring system based on distributed fiber grating sensing according to claim 1, wherein: when monitoring the girder stress of a monitored bridge, the fiber grating embedded type strain meter is bound on a steel bar framework before lining concrete is poured, the axial direction of the sensor needs to be parallel to the circumferential direction of a lining when the fiber grating embedded type strain meter is installed, the fiber grating embedded type strain meter is fixed on a steel bar by using a binding wire, a strain meter lead is fixed on the steel bar by using a binding belt and is led out along the steel bar, and the bending radius of the bending part is larger than about 5 cm; the fiber grating steel bar stress meter is installed by adopting a field welding method, the fiber grating steel bar stress meter is fixed at the position under a main rib, vibration damage during concrete pouring is avoided, a ribbon is utilized to fix a fiber grating steel bar stress meter lead to the steel bar and lead the lead out along the steel bar, the bending radius of the lead-out position needs to be more than 5cm, and all single-point sensors are led out by adopting parallel double-end leads.

4. The bridge health monitoring system based on distributed fiber grating sensing of claim 2, wherein: when monitoring the displacement of the expansion joint of the monitored bridge, firstly, a fiber grating displacement meter with a universal joint and a fixing bolt is used for measuring and installing hole positions on two sides of the gap, a hole is punched for installing a clamp, a sensor is installed on the clamp, the position and the height of the sensor are adjusted by paying attention to the displacement meter, one side of the displacement meter is fixed, certain tensile displacement is given, and the other side of the displacement meter is fixed.

5. The bridge health monitoring system based on distributed fiber grating sensing of claim 2, wherein: when the linear change of the deflection of the main beam of the monitored bridge is monitored, water tanks are placed at the positions of the main beams of the bridge, fiber grating static levels are arranged at intervals, and the water tanks are connected with the fiber grating static levels through water paths and are connected in series to form a same water path system; the method comprises the steps that the deflection of a bridge changes and is influenced by pressure generated by water level height difference in a fiber grating static level instrument, the wavelength of a fiber grating changes, then factory calibration parameters of the fiber grating static level instrument are combined, the measured wavelength change data of the fiber grating can be converted into vertical displacement, namely the deflection value of the bridge, meanwhile, the bridge deflection linear change monitoring adopts pier measurement installation, the fiber grating static level instrument is installed on a pier with the same elevation, a reference water tank and the fiber grating static level instrument are connected in series according to the sequence, one fiber grating static level is arranged at a reference point and used as a reference for settlement, and the rest of the fiber grating static levels are installed at designed settlement monitoring positions.

6. The bridge health monitoring system based on distributed fiber grating sensing of claim 2, wherein: when the stress of the prestressed steel beams of the external cable of the monitored bridge is monitored, 1 typical prestressed steel beam is selected for monitoring, the fiber bragg grating anchor cable dynamometer is customized and processed according to the diameter of the external cable and main anchoring force parameters on site, the fiber bragg grating anchor cable dynamometer is additionally arranged between an anchor cable seat and an anchor cable head, and the fiber bragg grating anchor cable dynamometer is used for detecting the tensioning pressure of the anchor cable in real time.

7. The bridge health monitoring system based on distributed fiber grating sensing of any one of claims 1 to 6, wherein: after all optical fiber sensing devices are laid, a multi-core communication optical cable is connected with a redundant optical fiber lead line in series, and the optical fiber sensing devices are led into an established monitoring station through a protection groove, so that data acquisition of all optical path signals in the monitoring station is finally realized, the system is monitored in a centralized manner, the overall monitoring unit is controlled in a networking manner, development of a related software system is matched, automatic measurement, storage and analysis are carried out, real-time online monitoring and monitoring results can be checked through a wireless transmission network and client software, and the purpose of automatic monitoring is finally achieved.

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