CN100538280C - A kind of high durability optical fiber grating wash out sensor - Google Patents
A kind of high durability optical fiber grating wash out sensor Download PDFInfo
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- CN100538280C CN100538280C CNB200710144305XA CN200710144305A CN100538280C CN 100538280 C CN100538280 C CN 100538280C CN B200710144305X A CNB200710144305X A CN B200710144305XA CN 200710144305 A CN200710144305 A CN 200710144305A CN 100538280 C CN100538280 C CN 100538280C
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Abstract
The invention provides a kind of high durability optical fiber grating wash out sensor.It comprises metal shell and is arranged in the metal shell and is connected the measure portion of metal shell, measure portion is made up of the FRP beam of uniform strength and two fiber gratings that are attached to FRP beam of uniform strength upper and lower surface, the extension line of fiber grating passes metal shell and draws, the inwall of metal shell is provided with metal baffle, be provided with calcium carbide above, the metal shell below is provided with transmission rod, be provided with the little rigid spring of precompressed between transmission rod one end and the metal shell inwall, the other end of transmission rod is provided with the FRP disk.Advantages such as this scour sensor has the precision height, it is convenient to lay, range and resolution are adjustable are suitable for the foundation soil flushing monitoring of civil engineering works structure health monitoring and the foundation soil flushing monitoring of structural test.
Description
(1) technical field
The present invention relates to a kind of building hydraulic engineering Quantitative Monitoring technology, being specifically related to a kind of is a kind of Quantitative Monitoring scour sensor.
(2) background technology
Monitoring structural health conditions has important meaning to the long-term safety operation that guarantees structure, and near the loss degree of foundation soil under the current scour effect of architecture basics is one of damage problem that attracts people's attention in the water conservancy civil engineering work.Foundation soil supports total by ground, bears structure all wt and vertical load, and the loss of a large amount of foundation soils not only has a significant impact structure durability, even can have influence on the security of structure.For example between overflow stage, near the bridge the Bridge Pier basis crosses that to wash away be to cause one of common cause that bridge lost efficacy.If can grasp the information that foundation soil is subjected to the degree of current scour in real time, adopt suitable means to save the situation just can effectively reduce the accident odds, the tenure of use of extending structure.
To the monitoring that foundation soil washes away, classic method generally can be divided into visual monitoring and instrument monitoring.Range estimation monitors that the method for generally taking has plummet depth measurement, Underwater Camera and frogman to touch spy; Instrument monitoring can be divided into retainer instrument monitoring and portable instrument monitoring again, and the principle of employing is sonar technique.Obviously, operated in accordance with conventional methods is complicated and be not suitable for long-term monitoring in real time, and the sensing and monitoring system that therefore adopts novel sensitive element exploitation foundation soil to wash away is one of major issue that needs to be resolved hurrily in the engineering.Fiber grating is one of sensitive element that is most widely used in the intellectual material systematic study at present, and its principle of work is the variation that the variation of external physical quantity causes fiber grating centre wavelength, by the measured value of variation acquisition of optical fiber Bragg centre wavelength.This measuring method thinking is simple, easy to operate, is easily numerous engineering technical personnel and accepts.The advantage of optical fiber grating sensing element mainly shows as: anti-electromagnetic interference (EMI); Corrosion-resistant; Quasi-distributed measurement, absolute measurement, signal attenuation are little; Highly sensitive, the precision advantages of higher.In addition, monitoring structural health conditions (SHM) worldwide progressively heats up in recent years, has become one of hot issue of world research, has also obtained great development as the fiber-optic monitoring system of monitoring structural health conditions important means.Therefore the optical fiber grating wash out sensor that is fit to the engineering application has great significance for the full optical fiber health monitoring systems that makes up large-scale building water conservancy structure.
By consulting and analyzing to the patent documentation of being correlated with both at home and abroad, less to flushing monitoring systematic study both at home and abroad based on fiber grating, only there is the associating of Taiwan State Seismological Bureau and National Taiwan University scour sensor to be studied, the principle of work of the scour sensor of its research is: utilize the effect of the moving hydraulic pressure of fiber grating monitoring to the cantilever disk, when sensor was buried by soil, its signal was a normal value substantially; When soil layer is washed away, when sensor enters water layer,, thereby learn that soil thickness changes because flowing pressure can make the strain of sensor senses fluctuate up and down.This method is based on the monitoring to flowing pressure, is applicable to when water velocity is big, and in order to obtain than high measurement accuracy or relatively large journey, need to increase wash away sensing probe number, also increased the layout density of sensor simultaneously.In order to improve permanance, this method needs to form confined space in optical fiber sensitive element place thorough seal, and is higher to technological requirement.
(3) summary of the invention
The object of the present invention is to provide a kind of have corrosion-resistant, sensing accuracy is high, the absolute measurement of anti-electromagnetic interference (EMI), quasi-distributed monitoring, physical quantity, can reuse and be easy to the high durability optical fiber grating wash out sensor of the bigger scope of networking monitoring.
The object of the present invention is achieved like this: it comprises metal shell and is arranged in the metal shell and is connected the measure portion of metal shell, measure portion is made up of the FRP beam of uniform strength and two fiber gratings that are attached to FRP beam of uniform strength upper and lower surface, the extension line of fiber grating passes metal shell and draws, the inwall of metal shell is provided with metal baffle, be provided with calcium carbide above, the metal shell below is provided with transmission rod, be provided with the little rigid spring of precompressed between transmission rod one end and the metal shell inwall, the other end of transmission rod is provided with the FRP disk.
The present invention also has some technical characterictics like this:
1, described metal shell top is provided with metal support, and measure portion is connected with metal support;
2, the extension line arranged outside of described fiber grating has the good teleflex of water proofing property, and draws from the metal shell below the baffle plate;
3, be provided with the bolt that resets below the described baffle plate;
4, described metal shell outer wall is provided with the precompressed sleeve;
5, described transmission rod is the FRP material.
The present invention is a kind of high durable optical fiber grating wash out sensor, be applicable to the variation in thickness of Quantitative Monitoring structure foundation soil under the souring of water, be applied to abominable building hydraulic engineering environment, have high-durability, high precision, simple in structure and be easy to advantages such as engineering laying.
Its principle of work is as follows: before installing, utilize reposition element to award the FRP beam of uniform strength one initial deformation, make the lower end of beam separate with all power transmission tightening latch, by designing requirement sensor is laid again and be installed in the foundation soil, extract reposition element then, make beam contact with first transmission rod.When the ground soil layer by current scour, make certain pre-buried soil pressure transmission rod and disk expose foundation soil, the FRP beam can eject it, and contact with the soil pressure bar of another pre-buried position, because two transmission rods and disk installation site and size is different, the strain of fiber grating institute perception is also different, and this moment, fiber grating can monitor a strain variation in theory, thereby learnt extraneous soil thickness information.Reposition element selects for use the bolt principle schematic that resets to see accompanying drawing 2 when being measured as a small amount of journey, and reposition element is that precompressed sleeve principle schematic is seen accompanying drawing 3 when being measured as wide range.
Technical characterictic of the present invention has:
1, measuring sensor is made up of the two naked gratings and the FRP beam of uniform strength, and two gratings are laid in beam of uniform strength inside or surperficial, and particular location can determine according to actual conditions;
2, the upper end inwall of metal shell has metal baffle, both can make gas be difficult to spill, and can place calcium carbide again, is used to produce the reliability that gas guarantees fluid-tight;
3, reposition element is set, can selects two kinds of schemes for use according to the difference of range: a kind of is that the bolt that resets is arranged below baffle plate, and another kind is to preset a precompressed sleeve at the metal shell outer wall;
4, above metal shell and the top of baffle plate requires a cast molding or uses the method for welding, but will guarantee to have good impermeability;
5, transmission rod is compared little 1 to 2 order of magnitude of beam of uniform strength rigidity with the spring rate that the disk place is provided with, and guarantees when disk is not subjected to soil pressure, and the beam of uniform strength can eject transmission rod and disk;
6, the disk of transmission rod will have the certain size requirement, guarantees that soil can provide the elastic force of the opposing beam of uniform strength;
7, the extension line of grating can be drawn optical fiber by the cover of perforate under baffle plate flexible pipe;
8, the FRP beam of uniform strength is rigidly connected by metal support and metal shell;
9, after washing away, can use reposition element that sensor is resetted, be convenient to measure next time.
In recent years, monitoring structural health conditions becomes one of hot issue of world research, and as its fiber grating of one of promising sensitive element also obtain huge development, at present, fiber-optic grating sensor has been widely used in fields such as civil engineering work, Aero-Space, petrochemical complex, medical science, environmental engineering, and the health monitoring systems that makes up full optical fiber also becomes one of developing goal of monitoring structural health conditions from now on.Sensor based on fiber grating is a kind of of fiber-optic monitoring system sensing probe, it is with the functional sensor of fiber grating as sensitive element, has the unrivaled advantage of other types Fibre Optical Sensor, mainly contain: good endurance, in the abominable structures such as building water conservancy of environment; Physical dimension by changing sensor, packing forms etc. can change range or precision easily; Good reliability, anti-electromagnetic interference capability is strong, and easily constitutes sensing network and be easy to install laying etc.
Beneficial effect of the present invention has:
1, the present invention is to be sensitive element with the fiber grating, utilizes the FRP beam of uniform strength as force transmission mechanism, and above selection of components makes this patent have the characteristics of high-durability.
2, the designed optical fiber grating wash out sensor of the present invention is directly monitored the thickness of the layer variation, rather than to the monitoring of flowing pressure, it is more responsive to the variation of pressure that the fiber grating and the FRP beam of uniform strength compound makes, therefore at flow rate of water flow hour, also can monitor foundation soil thickness and change slowly.
3, a sensor only needs two fiber gratings, and both convenient wiring can be saved expensive fiber Bragg grating (FBG) demodulator frequency of utilization again, and therefore under identical cost, that can monitor is wider, is beneficial to the structure of full fiber-optic monitoring system.
When 4, improving precision and range,, and do not need to increase expensive sensitive element, make cost further reduce as long as cheap plastics transmission rod is arranged in redesign as need.
5, shell is an open-top receptacle, can adopt a cast molding or welding fabrication, when guaranteeing sealing, can not influence follow-up operation.
6, sensor grating section adopts the encapsulating method of calcium carbide generation gas, and is convenient and reliable, to the stressed almost not influence of grating, makes measurement sensitivity higher, and degree of accuracy is higher.
7, the shell of sensor can adopt the method moulding that segmental machining is welded again, under the prerequisite of satisfying the demand again, makes that processing is convenient.
The present invention places the force transmission mechanism of being made up of the FRP beam of uniform strength, metal coating shell, plastics power transmission tightening latch with fiber grating, can monitor the scour sensor based on fiber grating that extraneous soil thickness changes thereby form one.The bare optical fibers and bare optical gratings and the FRP beam of uniform strength are compound, because FRP and fiber grating all have higher corrosion resistance, make measure portion that very high permanance be arranged, thereby the scour sensor of this patent have increased durability under wet environment.And the method that rivet by bolt FRP beam upper end links to each other with the metal shell top support, guarantees that the bearing place is solid.Metal baffle is connected with metal shell by the mode of welding.This sensor advantage is: corrosion-resistant, sensing accuracy is high, the absolute measurement of anti-electromagnetic interference (EMI), quasi-distributed monitoring, physical quantity, can reuse and be easy to the bigger scope of networking monitoring etc.At last, this optical fiber grating wash out sensor is suitable for the actual requirement of engineering of long term monitoring, and can be according to requirement of engineering, and by adjusting the rigidity of the beam of uniform strength, the length of power transmission tightening latch and number can be designed the sensor of different accuracy, different ranges.This optical fiber grating wash out sensor can be monitored the degradation degree of water conservancy structure foundation soil effectively, and the forewarning function can play under the flood erosion effect foundation soil excessive bleed time.This device is based on the sensitive element fiber grating, force transmission mechanism adopts the FRP beam of uniform strength and tightening latch, design ingenious, simple structure, adopted the mode of fluid-tight to seal neatly, do not needed the body seal waterproof, and each scour sensor only needs two gratings, reduce the frequency of utilization of expensive (FBG) demodulator, be beneficial in the middle of the full fiber-optic monitoring system that is integrated into structure, solved the problem that large-scale building water conservancy structure foundation soil washes away, have great practical application meaning.
(4) description of drawings
Fig. 1 is single probe scour sensor structural representation;
Fig. 2 is a plurality of probe scour sensor structural representations;
Fig. 3 is that a plurality of probes wash away the back synoptic diagram;
Fig. 4-Fig. 5 is single probe scour sensor fundamental diagram;
Fig. 6 is that metal baffle connects detail drawing;
Fig. 7 is the transmission rod organigram.
(5) embodiment
For example the present invention is done more detailed description below in conjunction with accompanying drawing:
Embodiment 1:
In conjunction with Fig. 1, present embodiment comprises following structure: metal shell 1 and the measure portion that is connected with metal shell 1 top metal bearing 3, it is made up of the upper and lower surface that two fiber gratings 4 are attached to the FRP beam of uniform strength 2, and this structure can be in the self compensation of guaranteeing to realize when fiber grating is to strain monitoring temperature; The outside of measure portion is the metal shell that shields; The inwall of metal shell 1 is provided with metal baffle 5, places a small amount of calcium carbide 6 above, has enough gas shields in order to guarantee measure portion, improves the sealing of measure portion; Reposition element is set, can select two kinds of schemes for use according to the difference of range: a kind of is that the bolt 7 that resets is arranged below baffle plate, another kind is to preset a precompressed sleeve at the metal shell outer wall, utilize reposition element to reset the FRP beam of uniform strength to original state, the installation of sensor is convenient in this design, and present embodiment adopts first kind of scheme; In addition, metal shell 1 below also is provided with the transmission rod 8 that several FRP materials are made, be provided with the little rigid spring 9 of precompressed between transmission rod 8 one ends and metal shell 1 inwall, be used for guaranteeing that no external force makes the time spent back-moving spring transmission rod 8 is resetted, the other end of transmission rod 8 is used for the variation of perception external world soil pressure for the FRP disk.Transmission rod 8 and disk acting in conjunction, the variation of the soil pressure of external world impression is passed to the relevant position of the FRP beam of uniform strength 2, measure the variation of the strain of the FRP beam of uniform strength 2 again by fiber grating, because the difference of the degree of crook at 8 pairs of fiber grating places of transmission rod of diverse location, the difference that causes fiber grating perception strain, the size of strain value just can be learnt the degree of washing away thus.
In conjunction with Fig. 4 concrete manufacture craft is described.Two naked gratings are encapsulated in the upper and lower surface of the FRP beam of uniform strength; The FRP beam of uniform strength and metal support adopt bolt 13 riveted joints, provide and prop up the border condition admittedly; Metal support adopts the mode of welding to be connected with metal shell; The baffle plate 5 of placing calcium carbide 6 is connected with metal shell 1 wall angle weld seam 12; Baffle plate guarantees good impermeability with a cast molding of metal shell or the welding fabrication on top, is convenient processing, and lower part is welding fabrication piecemeal; The extension line of fiber grating is protected with the good teleflex 10 of water proofing property, and draws from the metal shell perforate below the baffle plate, and road along the line is being provided with protection tube, destruction circuit when preventing to construct.Fig. 3 is the above section construction detail drawing of reposition element.
Fig. 4 is the transmission rod synoptic diagram, main herein structure is, the transmission rod place is being set, with the metal shell perforate, the little rigid spring 9 of a precompressed is set in inwall and transmission rod end again, the rigidity of spring determines that by beam of uniform strength rigidity the outer end disc size of transmission rod is determined by the size of soil pressure and the mechanical property and the beam of uniform strength rigidity of native medium.
Fig. 5 is for when adopting this scour sensor, and in order to reduce the influence of flowing pressure to signal, suggestion is vertical with water (flow) direction with opening direction (the transmission rod disk direction) laying of sensor.
Product of the present invention can adopt such method to design and produce:
At first determine the roughly rigidity of the beam of uniform strength, and then obtain the size of transmission rod disk according to the mechanical property of practical structures form and soil layer; Can select the spring of suitable rigidity then, lay transmission rod according to design accuracy again, consider to be convenient to discern strain variation, design the length of each bar; It is as follows to finish sensor production according to following operation at last:
The metal coating shell on welding or moulding by casting top; Paste fiber grating on FRP plate surface or the appropriate location below the surface, again the FRP plate is processed into beam of uniform strength shape, make the FRP beam of uniform strength of composite fiber grating (FBG).Guarantee after the moulding that grating is along the parallel distance two surperficial equidistant places that are in fibre reinforced plastics of beam length direction; Metal support is welded to the metal shell top, by the bolt connection beam of uniform strength is connected with metal support again; Baffle plate is welded on the metal shell inwall, and a small amount of calcium carbide of fixed placement; On metal shell, open two holes, be respectively applied for and draw optical fiber and reposition element is set; Lower case then installs transmission rod and spring; At last two shells are rigidly connected and get final product.
Embodiment 2:
In conjunction with Fig. 2, the basic structure of present embodiment is with embodiment 1, and difference is the second kind of scheme of employing that reset of present embodiment, promptly presets a precompressed sleeve 11 at the metal shell outer wall.
Claims (8)
1, a kind of high durability optical fiber grating wash out sensor, it comprises metal shell and is arranged in the metal shell and is connected the measure portion of metal shell, it is characterized in that measure portion is made up of the FRP beam of uniform strength and two fiber gratings being attached to FRP beam of uniform strength upper and lower surface, the extension line of fiber grating passes metal shell and draws, the inwall of metal shell is provided with metal baffle, be provided with calcium carbide above, the metal shell below is provided with transmission rod, be provided with the little rigid spring of precompressed between transmission rod one end and the metal shell inwall, the other end of transmission rod is provided with the FRP disk.
2, a kind of high durability optical fiber grating wash out sensor according to claim 1 is characterized in that described metal shell top is provided with metal support, and measure portion is connected with metal support.
3, a kind of high durability optical fiber grating wash out sensor according to claim 1 and 2 is characterized in that the extension line arranged outside of described fiber grating has the good teleflex of water proofing property, and draws from the metal shell below the baffle plate.
4, a kind of high durability optical fiber grating wash out sensor according to claim 1 and 2 is characterized in that described baffle plate below is provided with the bolt that resets.
5, a kind of high durability optical fiber grating wash out sensor according to claim 3 is characterized in that described baffle plate below is provided with the bolt that resets.
6, a kind of high durability optical fiber grating wash out sensor according to claim 1 and 2 is characterized in that described metal shell outer wall is provided with the precompressed sleeve.
7, a kind of high durability optical fiber grating wash out sensor according to claim 3 is characterized in that described metal shell outer wall is provided with the precompressed sleeve.
8, a kind of high durability optical fiber grating wash out sensor according to claim 1 is characterized in that described transmission rod is the FRP material.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB200710144305XA CN100538280C (en) | 2007-09-13 | 2007-09-13 | A kind of high durability optical fiber grating wash out sensor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB200710144305XA CN100538280C (en) | 2007-09-13 | 2007-09-13 | A kind of high durability optical fiber grating wash out sensor |
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| CN101140176A CN101140176A (en) | 2008-03-12 |
| CN100538280C true CN100538280C (en) | 2009-09-09 |
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| CNB200710144305XA Expired - Fee Related CN100538280C (en) | 2007-09-13 | 2007-09-13 | A kind of high durability optical fiber grating wash out sensor |
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Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103017675B (en) * | 2012-12-24 | 2016-02-10 | 东南大学 | A kind of push button pier subsidence monitoring device based on Bragg grating sensor |
| CN103017674A (en) * | 2012-12-24 | 2013-04-03 | 东南大学 | Cantilever pier scour monitoring device based on fiber Bragg grating sensors |
| CN103234723B (en) * | 2013-04-24 | 2016-01-20 | 南京理工大学 | Oscillatory type scour sensor |
| CN103759659B (en) * | 2014-01-27 | 2016-04-13 | 山东微感光电子有限公司 | A kind of fiber grating displacement sensor carrying out multimetering |
| CN104482876B (en) * | 2014-12-21 | 2017-09-05 | 天津大学前沿技术研究院有限公司 | Concrete abrasion and cavitation deepness real-time monitoring system based on chirped fiber grating |
| CN105825638B (en) * | 2016-06-01 | 2018-01-26 | 漳浦县圆周率工业设计有限公司 | A kind of optical fibre channel monitors seismic survey warning device |
| CN106917420B (en) * | 2017-01-09 | 2019-11-12 | 浙江工业大学 | A kind of pile foundation scour monitoring device |
| CN106894316B (en) * | 2017-02-28 | 2019-01-25 | 武汉理工大学 | A method of it is destroyed based on fiber-optic grating sensor detection asphalt pavement structure |
| CN113866215A (en) * | 2021-09-27 | 2021-12-31 | 中交第二航务工程局有限公司 | Attached type bridge pile foundation scouring product real-time monitoring system and method |
| CN114135118B (en) * | 2021-12-09 | 2022-08-09 | 同济大学 | FRP prestress monitoring and adjusting device and method capable of realizing intelligent service |
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2007
- 2007-09-13 CN CNB200710144305XA patent/CN100538280C/en not_active Expired - Fee Related
Non-Patent Citations (2)
| Title |
|---|
| 光纤监测技术在土木工程中的应用现状及展望. 乔迎欣，黎剑华，贺跃光.南昌工程学院学报，第26卷，卷第1期. 2007 |
| 光纤监测技术在土木工程中的应用现状及展望. 乔迎欣，黎剑华，贺跃光.南昌工程学院学报，第26卷，卷第1期. 2007 * |
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