CN110608678A - Deep horizontal displacement monitoring device based on Brillouin scattering optical fiber - Google Patents
Deep horizontal displacement monitoring device based on Brillouin scattering optical fiber Download PDFInfo
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 69
- 238000006073 displacement reaction Methods 0.000 title claims abstract description 40
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- 230000008859 change Effects 0.000 description 7
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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Abstract
The invention discloses a deep horizontal displacement monitoring device based on Brillouin scattering optical fibers, which is characterized by comprising a laser, distributed sensing optical fibers, an electro-optic modulator, an optical amplifier, a circulator, a coupler, an M-Z interferometer, an optical detector, a digital processor and a data communication and transmission module, wherein the laser is arranged on the deep horizontal displacement monitoring device; the distributed sensing optical fiber and the electro-optical modulator form an optical fiber sensing system, optical signals passing through the optical fiber sensing system are collected by the optical amplifier, the optical filter and the optical detector, collected processing data are transmitted to the microcontroller, the digital processor analyzes and processes the data, the data communication and transmission module transmits monitoring data results to the cloud platform, or the remote control measurement system sends control commands to measure at any time. The invention can detect the temperature, strain and other information of each point along the optical fiber deeply buried in the engineering structure in detail, and realize real-time monitoring and timely early warning.
Description
Technical Field
The invention belongs to the technical field of deep horizontal displacement monitoring, and relates to a deep horizontal displacement monitoring device based on Brillouin scattering optical fibers, which can be used for carrying out automatic, high-precision and predictable real-time dynamic monitoring on earth and rockfill dams, dykes, railway and highway slopes, rock and soil slopes, building foundations, mines, foundation pit excavation and underground structural engineering interiors.
Background
In order to reduce the loss caused by landslide disasters, the deep horizontal displacement monitoring method is widely applied to monitoring of side slopes, landslides and urban deep foundation pits, and the safety condition and the development trend of the method are evaluated and predicted. The monitoring of deep displacement of a side slope is an important link in a side slope monitoring system, and the main content is to measure the vertical displacement and the horizontal displacement of drill holes distributed on a side slope body so as to find out the displacement of different parts of the side slope and the like.
The currently common deep displacement monitoring technologies mainly comprise a borehole inclinometer, a guyed deep displacement meter, a multipoint displacement meter, a time domain reflection technology and the like. However, the sliding displacement meter cannot realize automatic measurement because the probe needs to move up and down along the inclinometer pipe in each measurement project; the measuring range of the fixed inclinometer is generally +/-10 degrees, and when the slope deformation exceeds the measuring range, the fixed inclinometer cannot continuously monitor; the pull-string type deep displacement meter can only measure the relative displacement, cannot determine the slope deformation direction, and cannot set the monitoring direction for it in advance. The pulse signals of the time domain reflection technology are easy to interfere, the slope deformation direction cannot be accurately determined, and accurate monitoring is difficult to obtain.
The optical fiber sensor has the characteristics of small volume, strong anti-interference capability, convenience for embedding materials or structures for nondestructive detection, wide dynamic range, high sensitivity and the like, so that the optical fiber sensor has obvious advantages compared with the traditional sensor and has very good application prospect in engineering practice. Fiber optic sensors are generally classified into electrical point type, quasi-distributed type, and fully-distributed type. The distributed optical fiber sensor has the advantages that the sensing parameters such as temperature, strain and the like at each point along the optical fiber can be continuously measured, the transmission distance is long, and the distributed optical fiber sensor is more suitable for horizontal displacement detection of projects such as slopes and foundation pits.
Such as brillouin scattering fiber technology:
brillouin scattering optical fiber sensing mechanism
Brillouin scattering is inelastic scattering of light excited by various elements in a medium, is a light scattering process generated by interaction of light waves and sound waves in the propagation process of an optical fiber, and the frequency change of the light scattering process represents the energy of the element excitation, so that the acoustic vibration in gas, liquid and solid can be researched. Under different conditions, brillouin scattering is expressed in the form of spontaneous scattering and invited scattering, respectively. The brillouin light has a frequency shift relative to the incident light, referred to as the brillouin frequency shift.
The change in the fiber brillouin shift with temperature and strain can be expressed as:
δνB＝CνTδTZ+CντδεZ
in the formula, deltaνBIs the amount of change in brillouin frequency shift,is the relative change of brillouin power; delta TzAnd delta epsilonZThe variation of the degree and strain of the optical fiber; cνTAnd CντRespectively representing Brillouin frequency shift temperature coefficient and strain coefficient; cPTAnd CPεRespectively the temperature coefficient and the strain coefficient of the brillouin power.
From brillouin frequency shift and temperatureAnd the relation with the strain, the direct influence of the Brillouin frequency shift receiving temperature and the strain can be seen. Calculating the temperature variation delta TzSum frequency strain change δ εZAnd the simultaneous measurement of temperature and strain can be realized.
The existing distributed optical fiber sensor based on Brillouin scattering mainly focuses on three aspects of research: brillouin optical time domain reflectometry (BODTR) techniques, brillouin optical analysis and analysis (BODTA) techniques, and Brillouin Optical Frequency Domain Analysis (BOFDA) techniques. The BOTDR technology has high spatial resolution and long detection distance, and has relatively mature research results in domestic and foreign research.
(II) distributed optical fiber sensor working principle based on Brillouin optical time domain reflectometry (BODTR) technology
A distributed optical fiber sensor based on a Brillouin Optical Time Domain Reflectometer (BOTDR) technology mainly utilizes backward spontaneous Brillouin scattering signals in the nonlinear effect of optical fibers to realize sensing measurement. The brillouin signal is affected by both temperature and strain, and as the temperature and strain vary throughout the fiber, the frequency shift and intensity of the brillouin signal changes. The frequency shift and the intensity change quantity of the Brillouin scattering signal have good linear relation with the changes of the temperature and the strain, so that the changes of the temperature and the strain of each part of the optical fiber can be obtained by detecting the frequency shift and the intensity of the Brillouin scattering signal, and the detection of the strain change of a monitored object is realized.
According to the working principle of the BOTDR technology, pulse light is injected into an optical fiber, spontaneous Brillouin scattering light is continuously excited when the pulse light propagates along the optical fiber, the backward propagating Brillouin scattering light is received by a detection system arranged at the starting end of the optical fiber, positioning of the scattering light can be realized according to the time difference between the emitted pulse light and the received spontaneous Brillouin scattering light, the obtained spontaneous Brillouin scattering light at different moments is processed, the distribution of the power or frequency shift of a Brillouin scattering signal is determined, and finally distributed measurement of temperature or strain is realized.
In the prior art, a lot of inventions relate to the technology of monitoring Brillouin scattering light and displacement, such as:
CN200410041124.0 optical fiber strain three-dimensional simulation experiment table, on which a displacement measuring instrument and a Brillouin scattering light time domain reflection measuring instrument are arranged, so that the measuring signal corresponds to the optical fiber deformation displacement phase shift, and the sensitivity and accuracy of the distributed optical fiber sensing system on the monitoring of the local deformation of the structure are tested. The experiment table explores a laying method of the sensing optical fiber and research and development of the distributed optical fiber sensor, and provides necessary experimental basis for applying the distributed optical fiber sensing technology to engineering practice.
CN200410041995.2 distributed optical fiber measuring method and system for deep deformation of soil body, the measuring system is composed of an inclinometer tube, a distributed optical fiber sensing circuit, a data acquisition device, a computer control module, a data processing module and the like. The method adopts a distributed optical fiber sensing technology based on a spontaneous Brillouin scattering principle, and lays sensing optical fibers on the outer surface of an inclinometer pipe in a comprehensive sticking mode, and then buries the inclinometer pipe in a soil body for measuring the deformation or displacement of the soil body. When the deep soil body displaces, the soil body drives the inclinometer pipe to deform, the strain capacity of the outer wall of the inclinometer pipe also changes, the strain distribution of the optical fiber adhered to the outer wall of the inclinometer pipe can be directly measured by adopting the BOTDR, the data acquisition process is realized by the computer control module, the acquired data is also guided into the data processing module by the computer control module, the deformation capacity of the inclinometer pipe is calculated according to a certain algorithm, and therefore the deformation or displacement of the soil body is obtained.
CN201010595164.5 distributed optical fiber advanced monitoring method for tunnel surrounding rock deformation, which comprises distributed optical fiber measuring tube, optical fiber sensing circuit, Brillouin back scattering light data acquisition equipment, and data processing and analyzing software; sensing optical fibers are symmetrically arranged on the outer surface of the PP-R pipe to manufacture a distributed optical fiber measuring pipe, and the displacement of a soil body along the measuring pipe can be obtained through the measuring pipe; the distributed optical fiber measuring tube is buried in a drilling hole of surrounding rock covered on a tunnel, the measuring tube which is formed by injecting a coupling agent and has soil-tube coordinated deformation is deformed along with synchronous displacement of the surrounding rock, and the deformation or displacement of the surrounding rock is monitored by measuring the deformation of the measuring tube. The method has the characteristics of distributed type, automatic data acquisition, real-time advanced monitoring and the like, and is suitable for monitoring the two-dimensional deformation or displacement of the surrounding rock in the geotechnical engineering fields of tunnel caverns, coal mine roadways and the like.
With the progress of the technology, if the internet of things technology is used for monitoring the safety condition of a side slope, a landslide or a deep foundation pit, the improvement of the deep displacement monitoring technology can be promoted by adopting a 4G or 5G network internet of things chip.
Disclosure of Invention
The invention aims to provide a deep horizontal displacement monitoring device based on Brillouin scattering optical fibers, which combines electro-optical modulators and M-Z interferometer technologies.
In order to achieve the purpose of the invention, the invention adopts the following technical scheme.
A deep horizontal displacement monitoring device based on Brillouin scattering optical fibers comprises a laser, distributed sensing optical fibers, an electro-optical modulator, an optical amplifier, a circulator, a coupler, an M-Z interferometer, an optical detector, a digital processor and a data communication and transmission module; the distributed sensing optical fiber and the electro-optical modulator form an optical fiber sensing system, optical signals passing through the optical fiber sensing system are collected by the optical amplifier, the optical filter and the optical detector, collected processing data are transmitted to the microcontroller, the digital processor analyzes and processes the data, the data communication and transmission module transmits monitoring data results to the cloud platform, or the remote control measurement system sends control commands to measure at any time.
Further, the distributed sensing optical fiber is installed inside the tested object or directly adhered on the surface of the tested object.
Further, the data communication and transmission module selects a 4G or 5G network chip, and transmits the acquired data to the cloud platform by using a 4G or 5G network.
Furthermore, the collected control command is sent to a collecting device on the engineering site through a data communication and transmission module, so that the functions of remote, real-time and safe measurement are realized.
The electro-optical modulator can realize the modulation of the phase, the amplitude intensity and the polarized state of the passing optical signal; the M-Z interferometer is used for separating Rayleigh scattering and Brillouin scattering in the backscattered light to realize the functions of Brillouin intensity detection and optical frequency discrimination; the light detector is used for detecting light power and converting the light power into corresponding current; the data communication and transmission system remotely transmits the acquired data to the data analysis and processing system, and the digital signal processor analyzes and processes the data to obtain detection information and present a detection result.
The invention can realize the automatic, high-precision, and predictable real-time dynamic monitoring of earth-rock dams, dykes, railway and highway slopes, rock-soil slopes, building foundations, mines, foundation pit excavation and underground structural engineering interiors.
Drawings
FIG. 1 shows the working process of the BOTDR optical fiber sensing system.
Fig. 2 is a system configuration diagram of a monitoring device according to an embodiment of the present invention.
Fig. 3 is an embodiment of a device for monitoring horizontal displacement in a deep portion of a foundation pit according to the present invention.
The specific implementation mode is as follows:
in order to make the objects, technical solutions and advantages of the present invention more clearly apparent, the present invention is further described below with reference to the accompanying drawings. It should be noted that the embodiments described herein are only for explaining the present invention, and are not intended to limit the present invention.
Example 1 to further illustrate the technical means of the present invention for achieving the intended purpose, an example of monitoring the horizontal displacement of a foundation pit (see fig. 3) is now described.
The invention provides a deep horizontal displacement monitoring device (see figure 2) based on Brillouin scattering optical fibers, which mainly comprises a laser, an electro-optical modulator, an optical amplifier, a circulator, a coupler, an M-Z interferometer, an optical detector, a data communication and transmission module and a digital signal processor.
The monitoring information comprises displacement size, displacement surface and the like of different parts in the monitored object body.
The sensing optical fiber is distributed sensing optical fiber, the arrangement mode of the sensing optical fiber is pre-embedded and laid, the sensing optical fiber can be installed in monitoring objects such as side slopes and foundation pits during pre-embedding, and can be directly adhered to the surface of a structure during laying.
The optical fiber sensing system is a distributed optical fiber sensing system based on Brillouin optical time domain reflectometry (B0TDR) technology.
The operation of the apparatus will now be described with reference to fig. 2 and 3. The laser of the incident end of the sensing optical fiber of the monitoring device emits laser, the laser is modulated by the modulator to become a beam of pulse light, and the pulse light enters the sensing optical fiber through the coupler through the circulator after being amplified by the optical amplifier. Brillouin scattering light and Rayleigh scattering light are simultaneously injected into the input end of the M-Z interferometer, and when the Brillouin frequency shift of the free path of the interferometer is twice, the Brillouin scattering light and the Rayleigh scattering light are respectively output at the two output ends of the interferometer, so that the separation of spontaneous Brillouin scattering and Rayleigh scattering signals in optical fiber backscattering is realized. The Brillouin scattering signal received by the optical detector is converted into a current signal, the current signal is amplified by the amplifier and then transmitted to the digital signal processor for data analysis and processing to obtain monitoring information and display a monitoring result, the signal transmission system transmits the monitored horizontal displacement result to the cloud platform through a 4G or 5G network so that a user can perform relevant application operations such as data analysis, storage, downloading and the like, and meanwhile, a remote measurement control command can be sent to a measuring device on an engineering site through the data communication and transmission module to perform remote measurement at any time and transmit data to the platform.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (4)
1. A deep horizontal displacement monitoring device based on Brillouin scattering optical fibers is characterized by comprising a laser, distributed sensing optical fibers, an electro-optical modulator, an optical amplifier, a circulator, a coupler, an M-Z interferometer, an optical detector, a digital processor and a data communication and transmission module; the distributed sensing optical fiber and the electro-optical modulator form an optical fiber sensing system, optical signals passing through the optical fiber sensing system are collected by the optical amplifier, the optical filter and the optical detector, collected processing data are transmitted to the microcontroller, the digital processor analyzes and processes the data, the data communication and transmission module transmits monitoring data results to the cloud platform, or the remote control measurement system sends control commands to measure at any time.
2. The deep horizontal displacement monitoring device based on the Brillouin scattering optical fiber according to claim 1, wherein the distributed sensing optical fiber is installed inside an object to be tested or directly adhered to the surface of the object to be tested.
3. The deep horizontal displacement monitoring device based on the Brillouin scattering optical fiber according to claim 1, wherein the data communication and transmission module adopts a 4G or 5G network chip, and transmits the acquired data to the cloud platform by using a 4G or 5G network.
4. The deep horizontal displacement monitoring device based on the Brillouin scattering optical fiber according to claim 1, wherein the collected control command is sent to a collecting device on an engineering site through a data communication and transmission module, so that the functions of remote, real-time and safe measurement are realized.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111877418A (en) * | 2020-08-25 | 2020-11-03 | 东北大学 | Real-time monitoring and early warning system for dynamic construction of deep foundation pit and using method |
| CN112361978A (en) * | 2020-11-04 | 2021-02-12 | 中铁第四勘察设计院集团有限公司 | Rock-soil body deformation monitoring device based on distributed optical fiber |
| CN113724480A (en) * | 2021-08-27 | 2021-11-30 | 吉林大学 | Monitoring and early warning system for influence of high-speed rail operation on ultrahigh and steep dangerous rocks above tunnel portal |
| CN114485442A (en) * | 2021-12-29 | 2022-05-13 | 国网新源控股有限公司 | Distributed dam panel deformation measurement method based on fixed-interval optical cables |
| CN114518095A (en) * | 2021-12-28 | 2022-05-20 | 湖北三江航天红峰控制有限公司 | Rock-soil mass deep displacement monitoring method |
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| CN105953724A (en) * | 2016-04-20 | 2016-09-21 | 北京信息科技大学 | Two-channel adjustable Mach-Zehnder interferometer |
| CN106482792A (en) * | 2016-11-21 | 2017-03-08 | 深圳市道桥维修中心桥梁检测站 | Bridge health monitoring system based on Brillouin distributed optical fiber sensing technology |
| CN210486800U (en) * | 2019-11-05 | 2020-05-08 | 东华理工大学 | Deep horizontal displacement monitoring device based on Brillouin scattering optical fiber |
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2019
- 2019-11-05 CN CN201911068178.9A patent/CN110608678A/en active Pending
Patent Citations (3)
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| CN105953724A (en) * | 2016-04-20 | 2016-09-21 | 北京信息科技大学 | Two-channel adjustable Mach-Zehnder interferometer |
| CN106482792A (en) * | 2016-11-21 | 2017-03-08 | 深圳市道桥维修中心桥梁检测站 | Bridge health monitoring system based on Brillouin distributed optical fiber sensing technology |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111877418A (en) * | 2020-08-25 | 2020-11-03 | 东北大学 | Real-time monitoring and early warning system for dynamic construction of deep foundation pit and using method |
| CN112361978A (en) * | 2020-11-04 | 2021-02-12 | 中铁第四勘察设计院集团有限公司 | Rock-soil body deformation monitoring device based on distributed optical fiber |
| CN113724480A (en) * | 2021-08-27 | 2021-11-30 | 吉林大学 | Monitoring and early warning system for influence of high-speed rail operation on ultrahigh and steep dangerous rocks above tunnel portal |
| CN114518095A (en) * | 2021-12-28 | 2022-05-20 | 湖北三江航天红峰控制有限公司 | Rock-soil mass deep displacement monitoring method |
| CN114485442A (en) * | 2021-12-29 | 2022-05-13 | 国网新源控股有限公司 | Distributed dam panel deformation measurement method based on fixed-interval optical cables |
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