A bridge safety monitoring method and monitoring mechanism based on optical fiber

Abstract

The invention discloses a bridge safety monitoring method based on optical fiber and a monitoring mechanism thereof, comprising the following steps: laying a sensing optical cable along the direction of the bridge structure, setting a three-dimensional acceleration structure on the bridge, and winding the sensing optical cable around the three-dimensional acceleration structure; placing an optical fiber displacement sensor at the connection of adjacent bridge decks, and communicating and connecting it with the input end of the optical fiber sensor through the sensing optical cable; communicating and connecting a coupler at the end of the sensing optical cable, and communicating and connecting a narrow line width pulse laser and an optical fiber vibration signal demodulation system through the coupler; transmitting light emitted by the narrow line width pulse laser into the sensing optical cable through the coupler, and transmitting reflected light returned by the sensing optical cable into the optical fiber vibration signal demodulation system through the coupler, and the optical fiber vibration signal demodulation system demodulating the vibration information of the bridge to evaluate the safety of the bridge; the method is convenient in construction, simple in operation, good in monitoring effect, high in monitoring accuracy, and has a wide range of application, and is applicable to any bridge.

Description

Technical Field

[0001] The invention relates to the technical field of bridge monitoring, and in particular to an optical fiber-based bridge safety monitoring method and a monitoring mechanism thereof. Background Art

[0002] With the rapid development of my country's economy, the country's investment in infrastructure has increased year by year. More and more bridges have been built across the country, and the problem of bridge safety monitoring has arisen. During the service of bridge structures, the coupling of disaster factors such as environmental erosion, material aging and load effects, man-made or natural mutation effects will inevitably lead to the accumulation of damage and resistance attenuation of bridge structures, thereby reducing the ability to resist natural disasters, normal loads and environmental effects, causing catastrophic emergencies, and causing major economic losses and casualties. Therefore, effective bridge structure safety management technology, timely monitoring of the safety and health status of bridge structures, and repair of early damage to bridge structures can not only significantly reduce maintenance costs, but also ensure the performance of bridge structures and extend the life of bridge structures, which has important social and economic value.

[0003] Bridge structure damage detection can be carried out by visual inspection, local damage detection based on instruments and equipment, structural damage detection based on static measurement data, and structural damage detection based on dynamic measurement data. However, the existing monitoring methods have few monitoring points, low monitoring accuracy, inconvenient construction, high cost, and are time-consuming and labor-intensive. Summary of the invention

[0004] The object of the present invention is to provide a bridge safety monitoring method based on optical fiber with high monitoring accuracy and multi-point monitoring and a monitoring mechanism thereof.

[0005] The technical solution of the present invention to solve the above technical problem is as follows: A bridge safety monitoring method based on optical fiber comprises the following steps:

[0006] Step ①: Lay the sensing optical cable along the bridge structure direction;

[0007] Step ②: setting a three-dimensional acceleration structure on the bridge, and winding the sensing optical cable around the three-dimensional acceleration structure;

[0008] Step 3: installing an optical fiber displacement sensor at the connection point of adjacent bridge decks, and connecting the sensing optical cable to the optical fiber displacement sensor for communication;

[0009] Step ④: Connect a coupler to the end of the sensing optical cable, and connect the coupler to the narrow linewidth pulse laser and the optical fiber vibration signal demodulation system respectively.

[0010] Step ⑤: Turn on the narrow linewidth pulse laser so that the light emitted by the narrow linewidth pulse laser enters the sensing optical cable through the coupler. The reflected light returned by the sensing optical cable enters the optical fiber vibration signal demodulation system through the coupler. The optical fiber vibration signal demodulation system demodulates the vibration information of the bridge and evaluates the safety of the bridge based on the demodulated vibration information.

[0011] Furthermore, in step ①, the sensing optical cable is laid along the bridge deck, support or pier.

[0012] Furthermore, the three-dimensional acceleration structure described in step ② is placed at the contact position between the bridge support and the bridge deck or the contact position between the bridge support and the bridge pier.

[0013] Furthermore, in step ①, the sensor cable is pre-laid when the bridge is constructed or laid after the bridge is completed.

[0014] The present invention also provides a monitoring mechanism of a bridge safety monitoring method based on optical fiber, comprising a sensing optical cable, a coupler, a narrow linewidth pulse laser, an optical fiber vibration signal demodulation system, and a three-dimensional acceleration structure wound with the sensing optical cable; the narrow linewidth pulse laser is communicatively connected to the coupler, the coupler is communicatively connected to the sensing optical cable, and the optical fiber vibration signal demodulation system is communicatively connected to the coupler;

[0015] The sensing optical cable is also communicatively connected with an optical fiber displacement sensor, and the optical fiber displacement sensor is located at the connection gap between adjacent bridge decks.

[0016] Furthermore, the three-dimensional acceleration structure includes a horizontal cantilever beam, a transverse cantilever beam and a longitudinal cantilever beam which are perpendicularly connected to each other along the three-dimensional direction of the bridge, and the sensing optical cable is respectively wound around the horizontal cantilever beam, the transverse cantilever beam and the longitudinal cantilever beam.

[0017] Furthermore, mass blocks are respectively installed on the horizontal cantilever beam, the transverse cantilever beam and the longitudinal cantilever beam.

[0018] Furthermore, the mass block is a cubic structure.

[0019] Furthermore, there are multiple three-dimensional acceleration structures, which are distributed at the positions where the bridge bearing contacts the bridge deck or the positions where the bridge bearing contacts the bridge pier.

[0020] The present invention has the following beneficial effects:

[0021] The light-based bridge safety monitoring method and monitoring mechanism provided by the present invention are convenient to construct, simple to operate, and have a wide range of applications. They are applicable to both highway and railway bridges and other bridges. Through optical fiber signal transmission monitoring and relative displacement monitoring between adjacent bridge decks, a dual monitoring system for bridge safety performance is realized, with good monitoring effect and high monitoring accuracy. The light emitted from the laser enters the optical cable, and the information reflected by the optical cable is transmitted to the optical fiber vibration signal demodulation system, and the overall situation of the bridge is obtained after analysis by the optical fiber vibration signal demodulation system, so that the monitoring effect is good. The optical fiber vibration signal demodulation system can realize intensity demodulation, phase demodulation, etc. The optical fiber displacement sensor can effectively and reliably monitor the relative displacement of the connection between adjacent bridge decks. The three-dimensional acceleration structure is used to accurately monitor multiple special positions of the bridge, and the strength of the vibration signal is increased by the mass block, so as to ensure that the cantilever beam of the three-dimensional acceleration structure can monitor the vibration in each direction, so as to realize three-dimensional monitoring. The method adopts distributed monitoring, realizes seamless monitoring recording, long monitoring distance, large monitoring range, and almost no monitoring blind spot, so as to improve the monitoring effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the present invention;

[0023] Figure 2 It is a structural schematic diagram of the three-dimensional acceleration structure in the present invention;

[0024] Figure 3 It is a schematic diagram of the optical fiber displacement sensor in the present invention;

[0025] Figures 1 to 3 The numbers shown in the figures represent respectively: 1-sensing optical cable, 2-three-dimensional acceleration structure, 3-optical fiber displacement sensor, 4-coupler, 5-narrow linewidth pulse laser, 6-optical fiber vibration signal demodulation system, 20-horizontal cantilever beam, 21-lateral cantilever beam, 22-longitudinal cantilever beam, 23-mass block. DETAILED DESCRIPTION

[0026] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0027] like Figures 1 to 3 As shown, a bridge safety monitoring method based on optical fiber, which picks up the vibration signal of the position where the sensing optical cable passes through by the optical fiber vibration signal demodulation system to judge the safe operation status of the bridge, includes the following steps:

[0028] Step ①: Lay the sensing optical cable 1 along the direction of the bridge structure; the bridge includes various types of bridges such as beam bridges, arch bridges, steel frame bridges, cable-supported bridges, etc. The laying of the sensing optical cable 1 can be preset when the bridge is built, or it can be installed on the bridge after the bridge is completed. The sensing optical cable 1 is mainly laid and distributed on the entire bridge deck, bridge supports, bridge piers, etc., and the vibration information of the bridge is obtained through the sensing optical cable 1.

[0029] Step ②: Set up a three-dimensional acceleration structure 2 on the bridge, and wind the sensing optical cable 1 around the three-dimensional acceleration structure 2; the three-dimensional acceleration structure 2 is mainly set up at the position where the bridge support contacts the bridge deck, and at the bridge support and bridge pier. The three-dimensional acceleration or force condition at the setting position is monitored by the three-dimensional acceleration structure 2 in conjunction with the sensing optical cable 1.

[0030] Step ③: Place the optical fiber displacement sensor 3 at the connection between adjacent bridge decks, and the sensing optical cable 1 is communicatively connected to the input end of the optical fiber sensor; the optical fiber displacement sensor is mainly arranged at the connection between adjacent bridge decks, so as to facilitate monitoring the relative position changes of adjacent bridge decks.

[0031] Step ④: The end of the sensing optical cable 1 is connected to the coupler 4 for communication, and the narrow line width pulse laser 5 and the optical fiber vibration signal demodulation system 6 are respectively connected to the coupler 4 for communication. The light emitted by the narrow line width pulse laser 5 enters the sensing optical cable 1 through the coupler 4, and the reflected light returned by the sensing optical cable 1 enters the optical fiber vibration signal demodulation system 6 through the coupler 4.

[0032] Step ⑤: Turn on the narrow line width pulse laser 5, and let the light emitted by the narrow line width pulse laser 5 enter the sensing optical cable 1 through the coupler 4, and let the reflected light returned by the sensing optical cable 1 enter the optical fiber vibration signal demodulation system 6 through the coupler 4. The optical fiber vibration signal demodulation system 6 demodulates the vibration information of the bridge, and evaluates the safety of the bridge based on the demodulated vibration information. The optical fiber vibration signal demodulation system can also adopt an optical fiber vibration sensing signal demodulation system. The working principle of the optical fiber vibration signal demodulation system 6 may include demodulation methods such as intensity demodulation and phase demodulation.

[0033] The main characteristic parameters of the optical signal mainly include light intensity, phase, polarization state, etc. When vibration occurs near the sensing optical cable 1, the characteristic parameters of the optical signal in the sensing optical cable 1 will change; the optical signal reflected back by the sensing optical cable 1 will carry vibration information, and the reflected optical signal enters the optical fiber vibration signal demodulation system 6 through the coupler 4. The demodulation system processes the received optical signal and restores the vibration information of the bridge, and evaluates the safety status of the bridge based on the vibration information.

[0034] Embodiment: In this example, the optical fiber vibration signal demodulation system 6 selects an optical fiber vibration signal phase demodulation system. Several main characteristic parameters of the optical signal are light intensity, phase, polarization state, etc. When vibration occurs, the characteristic parameters of the optical signal will change. The working mode of the optical fiber vibration signal phase demodulation system is to demodulate the phase information of the optical signal through an existing algorithm.

[0035] In actual operation, the narrow line width pulse laser 5, the optical fiber vibration signal phase demodulation system, and the optical cable laid on the bridge are connected through the coupler 4 according to the implementation steps of the specific implementation plan. After the entire system is debugged, the light generated by the narrow line width pulse laser 5 enters the optical cable through the coupler 4. When a car passes on the bridge, water flows hit the bridge pier, and other situations occur, certain parameters (such as phase) of the light entering the optical cable will change. The optical signal carrying these vibration information and reflected by the optical cable enters the optical fiber vibration signal phase demodulation system through the coupler 4. When the bridge vibrates, the phase of the light transmitted in the optical cable changes. The optical fiber vibration signal phase demodulation system receives the optical signal and demodulates its phase. According to the phase change of the optical signal, the vibrating part can be located and the vibration amplitude can be judged, so that the overall situation of the bridge can be evaluated to avoid accidents. This method is convenient to construct, simple to operate, and has a wide range of applications. It is applicable to both highway and railway bridges and other bridges.

[0036] The present invention also provides a monitoring mechanism for a bridge safety monitoring method based on optical fiber, comprising a sensing optical cable 1, a coupler 4, a narrow linewidth pulse laser 5, an optical fiber vibration signal demodulation system 6, and a three-dimensional acceleration structure 2 wrapped with the sensing optical cable 1; the narrow linewidth pulse laser 5 is communicatively connected to the coupler 4, the coupler 4 is communicatively connected to the sensing optical cable 1, and the optical fiber vibration signal demodulation system 6 is communicatively connected to the coupler 4, the narrow linewidth pulse laser 5 adopts a pulse laser of the Koheras BASIKd series, the sensing optical cable 1 adopts a single-mode optical cable of the JXL-GYXTW-4B1.3 model, and the coupler 4 adopts a single-mode optical coupler 4.

[0037] The sensing optical cable 1 is also communicatively connected with an optical fiber displacement sensor 3, and the optical fiber displacement sensor 3 is located at the connection gap between adjacent bridge decks.

[0038] The three-dimensional acceleration structure 2 includes a horizontal cantilever beam 20, a transverse cantilever beam 21 and a longitudinal cantilever beam 22 which are vertically connected to each other along the three-dimensional direction of the bridge, and the sensing optical cable 1 is wound around the horizontal cantilever beam 20, the transverse cantilever beam 21 and the longitudinal cantilever beam 22 respectively.

[0039] Mass blocks 23 are respectively installed on the horizontal cantilever beam 20, the transverse cantilever beam 21 and the longitudinal cantilever beam 22. The mass blocks 23 are cube structures. The vibration signal is made more obvious by the mass blocks 23, and the cube structure ensures the uniformity of the distribution of the vibration signal.

[0040] There are multiple three-dimensional acceleration structures 2, and they are distributed at the positions where the bridge bearing contacts the bridge deck or the positions where the bridge bearing contacts the bridge pier, so as to form three-dimensional multi-point monitoring of the position and improve the monitoring effect.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A bridge safety monitoring method based on optical fiber, characterized in that: Monitoring is performed using a monitoring mechanism, the monitoring mechanism comprising a sensing optical cable (1), a coupler (4), a narrow linewidth pulse laser (5), an optical fiber vibration signal demodulation system (6), and a three-dimensional acceleration structure (2) wound with the sensing optical cable (1); the narrow linewidth pulse laser (5) is communicatively connected to the coupler (4), the coupler (4) is communicatively connected to the sensing optical cable (1), and the optical fiber vibration signal demodulation system (6) is communicatively connected to the coupler (4). The sensing optical cable (1) is also communicatively connected to an optical fiber displacement sensor (3), and the optical fiber displacement sensor (3) is located at a connection gap between adjacent bridge decks; The three-dimensional acceleration structure (2) comprises a horizontal cantilever beam (20), a transverse cantilever beam (21) and a longitudinal cantilever beam (22) respectively along the three-dimensional direction of the bridge and vertically connected to each other, and the sensing optical cable (1) is respectively wound around the horizontal cantilever beam (20), the transverse cantilever beam (21) and the longitudinal cantilever beam (22); Mass blocks (23) are respectively installed on the horizontal cantilever beam (20), the transverse cantilever beam (21) and the longitudinal cantilever beam (22); When conducting monitoring, the following steps are involved: Step ①: Laying the sensing optical cable (1) along the direction of the bridge structure; Step ②: a three-dimensional acceleration structure (2) is arranged on the bridge, and the sensing optical cable (1) is wound around the three-dimensional acceleration structure (2); the three-dimensional acceleration structure (2) is placed at a contact position between a bridge support and a bridge deck or a contact position between a bridge support and a bridge pier; a mass block is installed on the three-dimensional acceleration structure (2); Step ③: arranging an optical fiber displacement sensor (3) at the connection point between adjacent bridge decks, and connecting the sensing optical cable (1) to the input end of the optical fiber displacement sensor (3) for communication; Step ④: A coupler (4) is communicatively connected to the end of the sensing optical cable (1), and the coupler (4) is communicatively connected to a narrow linewidth pulse laser (5) and an optical fiber vibration signal demodulation system (6) respectively; Step ⑤: Turn on the narrow linewidth pulse laser (5), so that the narrow linewidth pulse laser (5) emits light that enters the sensing optical cable (1) through the coupler (4), and the reflected light returned by the sensing optical cable (1) enters the optical fiber vibration signal demodulation system (6) through the coupler (4). The optical fiber vibration signal demodulation system (6) demodulates the vibration information of the bridge, and evaluates the safety of the bridge based on the demodulated vibration information.

2. The optical fiber-based bridge safety monitoring method according to claim 1, characterized in that: In step ①, the sensing optical cable (1) is laid along the bridge deck, support or pier.

3. The monitoring method of a bridge safety monitoring method based on optical fiber according to claim 1, characterized in that: The mass block (23) is a cubic structure.

4. The monitoring method of a bridge safety monitoring method based on optical fiber according to claim 3 is characterized in that: The three-dimensional acceleration structures (2) are multiple and distributed at the positions where the bridge support contacts the bridge deck or the positions where the bridge support contacts the bridge pier.

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