Dam riverbed scouring monitoring system and method based on optical fiber dynamic strain sensing

Abstract

The invention provides a dam riverbed scouring monitoring system and method based on optical fiber dynamic strain sensing, and the method comprises the steps: enabling distributed optical fiber sensors to be pre-bonded and attached to a cantilever beam structure according to a certain rule, and forming a dynamic strain response signal sensing network through a one-dimensional space coordinate system; vibration excitation is carried out on the cantilever beam structure through the knocking effect of the impact hammer; a dynamic strain response signal is obtained through a distributed optical fiber sensor attached to the cantilever beam structure damage; the monitoring result is preprocessed through the lower machine position and then subjected to frequency domain analysis, the inherent frequency of the cantilever structure at different moments is obtained, the inherent frequency is analyzed and calculated, and the result is returned to the upper machine position to be displayed and stored; according to the monitoring system and method provided by the invention, the complexity of system sensor arrangement and communication cable wiring can be reduced, the system operation and maintenance cost is reduced, and the environment adaptability of the monitoring system and the monitoring method is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of river channel status monitoring, and in particular to a dam riverbed scour monitoring system and method based on optical fiber dynamic strain sensing. Background Art

[0002] Dams are used for reservoir water storage, flood control and power generation purposes. They must withstand the impact of various natural disasters. Dam riverbed scour is one of the main causes of dam failure. Dam riverbed scour may weaken the structural stability of the dam and increase the risk of dam failure. Therefore, autonomous and continuous scour monitoring through permanent instruments is necessary to prevent failures caused by scour. Effective monitoring of dam riverbed scour can obtain the actual scour depth of the bottom and provide accurate and effective data for the implementation of riverbed scour protection methods.

[0003] In the past few decades, scholars at home and abroad have invented many methods for scour monitoring. Traditional monitoring methods can be divided into three categories according to the different measurement objects, namely reference monitoring, soil-water interface monitoring and structural monitoring. The mainstream in reference monitoring currently uses magnetic sliding collars, floating devices, etc., among which the floating devices are when the scour depth reaches its position, these devices will float out and are programmed to send remote signals to provide warnings, but they need to be reinstalled when they float out. The advantages are easy installation and operation, and the disadvantage is that they need to be battery-driven, which limits their short-term use. Sonar, radar, time domain reflectometer, etc. are currently used in soil-water interface monitoring. The advantages of sonar are easy installation; the refilling process can be monitored; accurate data collection, but the disadvantage is that the accuracy and use are heavily dependent on distance and installation. Time domain reflectometers use devices using this method to work well in monitoring the scour depth at a specific location, but require expensive underwater installation and are easily affected by background radiation. These traditional scour monitoring studies mainly focus on scour monitoring of underwater instruments, but these types of scour monitoring methods have some problems, such as easy offline, low monitoring accuracy, high cost, poor stability and short durability of sensor elements. Therefore, these methods have great limitations in engineering.

[0004] Therefore, there is an urgent need for a dam riverbed scour monitoring system and method based on optical fiber dynamic strain sensing that can solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a dam riverbed scour monitoring system and method based on optical fiber dynamic strain sensing. The monitoring system and method provided by the present invention have strong environmental adaptability and low complexity, and can be used for dam riverbed scour monitoring.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a dam riverbed scour monitoring system based on optical fiber dynamic strain sensing, comprising a cantilever beam structure, a distributed optical fiber sensor is bonded and attached to the surface of the cantilever beam structure, the distributed optical fiber sensor is constructed into a dynamic strain response signal sensing network through a one-dimensional space coordinate system, the distributed optical fiber sensor establishes communication with a lower machine position, the lower machine position establishes communication with an upper machine position, the lower machine position is used to process and calculate the dynamic strain response signal, and the upper machine position is used to display and store the results.

[0008] Preferably, the cantilever beam structure has a reference point, and taking the reference point as the origin, the one-dimensional space coordinate system is formed on the cantilever beam structure along the length direction of the distributed optical fiber sensor.

[0009] Preferably, it also includes an excitation source, and the excitation source is an impact hammer.

[0010] The present invention also provides a method for monitoring riverbed scour of a dam based on optical fiber dynamic strain sensing, comprising the following steps:

[0011] S1. Adhere the distributed optical fiber sensor to the surface of the cantilever beam structure according to the layout rules to form a dynamic strain response signal sensing network;

[0012] S2. Determine the sampling point and obtain its position coordinates;

[0013] S3. The cantilever beam structure is buried in a riverbed with a certain burial depth, and vibration excitation is performed on it by an impact hammer;

[0014] S4. The lower position collects the dynamic strain response signal of each sampling point in the dynamic strain response signal sensing network through the amplitude transfer-Brillouin optical time domain analysis technology, and pre-processes the dynamic strain response signal;

[0015] S5. The lower position performs frequency domain processing on the pre-processed dynamic strain response signal to obtain the natural frequency of the cantilever beam structure;

[0016] S6. The natural frequency f0 of the cantilever beam structure at the initial buried depth and the natural frequency f of the cantilever beam structure at time t t Conduct analysis, establish indicators of the relationship between scour depth and natural frequency, and send the indicators to the upper machine for display and storage.

[0017] Preferably, step S2 is specifically as follows: select a reference point in the space of the cantilever beam structure, establish a one-dimensional space coordinate system with the reference point as the coordinate origin, select the spatial resolution and sampling interval of the distributed optical fiber sensor according to the riverbed scour monitoring requirements, and obtain the position coordinates of the sampling point in the one-dimensional space coordinate system according to the layout rules, spatial resolution and sampling interval of the distributed optical fiber sensor.

[0018] Preferably, in step S4, the preprocessing includes calibration, trend item removal and smoothing and denoising.

[0019] Preferably, in step S5, the natural frequency of the cantilever beam structure is obtained by Fourier transform.

[0020] Compared with the prior art, the present invention has achieved the following beneficial technical effects:

[0021] The present invention provides a dam riverbed scour monitoring system and method based on optical fiber dynamic strain sensing, wherein distributed optical fiber sensors are pre-bonded and attached to a cantilever beam structure according to certain rules, and a dynamic strain response signal sensing network is formed through a one-dimensional space coordinate system; the cantilever beam structure is vibrated and excited by the striking action of an impact hammer; the dynamic strain response signal is obtained by the distributed optical fiber sensor attached to the cantilever beam structure; the monitoring result is pre-processed at a lower position and then analyzed in the frequency domain to obtain the natural frequency of the cantilever structure at different times, the natural frequency is analyzed and calculated, and the result is returned to an upper position for display and storage; the monitoring system and method proposed by the present invention can reduce the complexity of system sensor layout and communication cable wiring, reduce system operation and maintenance costs, and improve the environmental adaptability of the monitoring system and monitoring method. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 A schematic diagram of a dam riverbed scour monitoring system based on optical fiber dynamic strain sensing provided by the present invention;

[0024] Figure 2 A schematic diagram of a one-dimensional spatial coordinate system in a dam riverbed scour monitoring system based on optical fiber dynamic strain sensing provided by the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The purpose of the present invention is to provide a dam riverbed scour monitoring system and method based on optical fiber dynamic strain sensing to solve the problems existing in the prior art.

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Embodiment 1:

[0029] This embodiment provides a dam riverbed scour monitoring system based on optical fiber dynamic strain sensing. Figure 1 and 2 As shown, it includes a cantilever beam structure 101, and a distributed optical fiber sensor 102 is bonded and attached to the surface of the cantilever beam structure 101. The distributed optical fiber sensor 102 is constructed into a dynamic strain response signal sensing network 107 through a one-dimensional space coordinate system 201. The distributed optical fiber sensor 102 establishes communication with the lower machine position 105, and the lower machine position 105 establishes communication with the upper machine position 106. The lower machine position 105 is used to process and calculate the dynamic strain response signal, and the upper machine position 106 is used to display and store the results.

[0030] Specifically, a reference point 202 is provided on the cantilever beam structure 101 . With the reference point 202 as the origin, a one-dimensional space coordinate system 201 is formed on the cantilever beam structure 101 along the length direction of the distributed optical fiber sensor 102 .

[0031] Furthermore, an excitation source 104 is included, and the excitation source 104 is an impact hammer.

[0032] This embodiment also provides a method for monitoring embankment riverbed scour based on optical fiber dynamic strain sensing, comprising the following steps:

[0033] S1. The distributed optical fiber sensor 102 is bonded and attached to the surface of the cantilever beam structure 101 according to the layout rules to form a dynamic strain response signal sensing network 107;

[0034] S2. Determine the sampling point 103 and obtain its position coordinates; specifically: select a reference point 202 in the space of the cantilever beam structure 101, establish a one-dimensional space coordinate system 201 with the reference point 202 as the coordinate origin, select the spatial resolution and sampling interval of the distributed optical fiber sensor 102 according to the riverbed scour monitoring requirements, and obtain the position coordinates of the sampling point 103 in the one-dimensional space coordinate system 201 according to the layout rules, spatial resolution and sampling interval of the distributed optical fiber sensor 102;

[0035] S3. The cantilever beam structure 101 is buried in a riverbed having a certain depth, and is vibrated by an impact hammer;

[0036] S4. The lower position 105 collects the dynamic strain response signal of each sampling point in the dynamic strain response signal sensing network through the amplitude transfer-Brillouin optical time domain analysis technology, and preprocesses the dynamic strain response signal; the preprocessing includes calibration, trend item removal and smoothing denoising;

[0037] S5. The lower machine position 105 performs frequency domain processing on the pre-processed dynamic strain response signal, and obtains the natural frequency of the cantilever beam structure through Fourier transform;

[0038] S6. The natural frequency f0 of the cantilever beam structure 101 at the initial buried depth of the lower machine position 105 and the natural frequency f of the cantilever beam structure at time t t An analysis is performed to establish an index of the relationship between the scouring depth and the natural frequency, and the index is sent to the upper machine position 106 for display and storage.

[0039] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A dam riverbed scour monitoring system based on optical fiber dynamic strain sensing, comprising a cantilever beam structure, characterized in that: A distributed optical fiber sensor is bonded and attached to the surface of the cantilever beam structure. The distributed optical fiber sensor is constructed into a dynamic strain response signal sensing network through a one-dimensional spatial coordinate system. The distributed optical fiber sensor establishes communication with a lower machine position, and the lower machine position establishes communication with an upper machine position. The lower machine position is used to process and calculate the dynamic strain response signal, and the upper machine position is used to display and store the results.

2. The embankment and riverbed scour monitoring system based on optical fiber dynamic strain sensing according to claim 1 is characterized in that: The cantilever beam structure has a reference point, and taking the reference point as the origin, the one-dimensional space coordinate system is formed on the cantilever beam structure along the length direction of the distributed optical fiber sensor.

3. The embankment and riverbed scour monitoring system based on optical fiber dynamic strain sensing according to claim 1 is characterized in that: The device also comprises an excitation source, which is an impact hammer.

4. A method for monitoring riverbed scour of dams based on optical fiber dynamic strain sensing, characterized in that: The following steps are involved: S1. Adhere the distributed optical fiber sensor to the surface of the cantilever beam structure according to the layout rules to form a dynamic strain response signal sensing network; S2. Determine the sampling point and obtain its position coordinates; S3. The cantilever beam structure is buried in a riverbed with a certain burial depth, and vibration excitation is performed on it by an impact hammer; S4. The lower position collects the dynamic strain response signal of each sampling point in the dynamic strain response signal sensing network through the amplitude transfer-Brillouin optical time domain analysis technology, and pre-processes the dynamic strain response signal; S5. The lower position performs frequency domain processing on the pre-processed dynamic strain response signal to obtain the natural frequency of the cantilever beam structure; S6. The natural frequency f0 of the cantilever beam structure at the initial buried depth and the natural frequency f of the cantilever beam structure at time t t Conduct analysis, establish indicators of the relationship between scour depth and natural frequency, and send the indicators to the upper machine for display and storage.

5. The method for monitoring embankment and riverbed scour based on optical fiber dynamic strain sensing according to claim 4 is characterized in that: Step S2 is specifically as follows: select a reference point in the space of the cantilever beam structure, establish a one-dimensional space coordinate system with the reference point as the coordinate origin, select the spatial resolution and sampling interval of the distributed optical fiber sensor according to the riverbed scour monitoring requirements, and obtain the position coordinates of the sampling point in the one-dimensional space coordinate system according to the layout rules, spatial resolution and sampling interval of the distributed optical fiber sensor.

6. The method for monitoring embankment and riverbed scour based on optical fiber dynamic strain sensing according to claim 4, characterized in that: In step S4, the preprocessing includes calibration, trend item removal and smoothing and denoising.

7. The method for monitoring embankment and riverbed scour based on optical fiber dynamic strain sensing according to claim 4 is characterized in that: In step S5, the natural frequency of the cantilever beam structure is obtained by Fourier transform.

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