CN112880578A - System and method suitable for monitoring dislocation of airport pavement seam structure - Google Patents
System and method suitable for monitoring dislocation of airport pavement seam structure Download PDFInfo
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- CN112880578A CN112880578A CN202011580893.3A CN202011580893A CN112880578A CN 112880578 A CN112880578 A CN 112880578A CN 202011580893 A CN202011580893 A CN 202011580893A CN 112880578 A CN112880578 A CN 112880578A
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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
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/165—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by means of a grating deformed by the object
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
- G01K11/3206—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres at discrete locations in the fibre, e.g. using Bragg scattering
Abstract
The invention discloses a slab staggering monitoring system and a slab staggering monitoring method suitable for an airport pavement joint structure, wherein the monitoring method is based on the Cincisco classical theory of iron wood, a monitoring signal of a dowel bar with FBGs is converted into vertical deformation of a joint structure slab end, and the slab end vertical deformation at the position of the dowel bar with the FBGs at the joint can reflect the slab staggering deformation size and the slab staggering deformation form of a tested area of a concrete slab; the monitoring system that this application provided is used for airport runway to miss platform deformation monitoring, arranges the board end vertical deformation of dowel steel position department of FBG through seam crossing and can reflect the wrong platform form in concrete slab measured area, and this system is applicable to the monitoring that the road surface seam structure missed platform warp.
Description
Technical Field
The invention relates to the field of wrong station monitoring at a joint structure of a flying area of a civil aviation airport runway, in particular to a sensing technology applied to a dowel bar with FBGs (fiber Bragg gratings) arranged at the joint structure.
Background
When evaluating the performance of a flight area, the flatness of the road surface is one of the most important indexes, and the flatness of the road surface directly influences the landing and gliding safety of an aircraft and has an important influence on the service life of the road surface. The method has the advantages that the concrete pavement slab of the runway sinks in the flight area, the runway is free from falling, obvious temperature gradient exists in the pavement slab, the pavement slab can be bent at the slab corners or the slab edges, the slab staggering is formed at the joints, and the smoothness of the pavement is directly influenced, so that the method is very necessary for monitoring the slab staggering, the traditional method for monitoring the slab staggering of the pavement slab of the airport mainly depends on manual measurement by using a straight ruler or a triangular ruler, the automation degree is low, the measurement operation needs to be carried out by using flight gaps and daytime time, and the monitoring process is influenced because the manual measurement needs to be carried out by joints one by one in the monitoring process; and because the manual work can not monitor in real time, the dislocation deformation generated in the runway can not be found in time. According to the monitoring requirement of civil aviation road surfaces, a monitoring technology which can be used all day long, is not interfered by environment, has small interference on airport navigation and has high automation degree is needed to be researched and developed.
The application of optical fiber sensing technology to airport runways has been studied and applied in recent decades, but mainly, optical fibers are embedded in pavement structure layers (most of the surface layers are asphalt and concrete layers) to monitor pavement temperature changes and pavement dynamic response under the load of aircrafts, the use of optical fiber sensing technology to monitor deformation and displacement of the airport runways is currently studied, and particularly, the technology suitable for monitoring the dislocation of joints is still in the research stage. Although the optical fiber monitoring technique has excellent "sensing" and "measuring" functions, it has a major technical obstacle in practical application due to its inherent viability and compatibility with the deformation of the surrounding structural materials.
Aiming at the problem, the invention provides an optical fiber sensing technology suitable for monitoring the dislocation of the joint of the airport runway, and the technology designs an FBG-dowel steel based on an FBG sensing principle and a joint structure load transmission and stress deformation principle; based on the Cisco classical theory of iron wood, a method for converting monitoring signals of a dowel bar containing FBGs into vertical deformation of a plate end of a joint structure is provided, the monitoring signals on the dowel bar with the FBGs can reflect the slab staggering deformation size and the deformation form of a tested area of a concrete slab through calculation and analysis by a signal conversion method of the vertical deformation size of the plate end through the joint structure.
Disclosure of Invention
In view of the above-mentioned deficiencies of the prior art, an object of the present invention is to provide an optical fiber monitoring technique, wherein a plurality of FBGs are embedded in a dowel bar to form the dowel bar with the FBGs, and a monitoring signal on the dowel bar with the FBGs is converted by a signal conversion method according to the vertical deformation of the slab end through a joint structure, so as to reflect the slab staggering deformation and the deformation form of the measured area of the concrete slab through calculation and analysis. The technology is used for monitoring the dislocation deformation of the runway and is suitable for monitoring the dislocation deformation of the pavement joint structure by optical fibers.
In order to achieve the purpose, the invention adopts the technical scheme that: the utility model provides a be applicable to airport pavement seam structure wrong platform monitoring system, passes the form including the dowel bar that arranges FBG, arranges the form method, and FBG monitoring signal conversion is wrong platform deformation method on the dowel bar. At least 5 FBGs are embedded in shallow grooves formed in the dowel bar in the joint needing dislocation monitoring, wherein the FBGs at least comprise 4 FBGs for monitoring strain of the dowel bar and one FBG for monitoring temperature, and the temperature sensing FBG is used for temperature compensation processing; the FBGs that monitor meeting an emergency are arranged along midpoint position symmetry at the dowel steel, and all FBGs that monitor meeting an emergency arrange the position on the dowel steel and all be close to the midpoint position and paste and fix in the bottom of dowel steel shallow recess, and monitoring temperature sensor makes it not influenced by the dowel steel deformation at FBG grating inscription section plus sleeve pipe. According to the sinco theory of iron and wood, the bending moment and the shearing force transmitted by the dowel bar are obtained through the strain magnitude monitored by the FBG, and the FBG monitoring signal is finally converted into the vertical deformation magnitude of the plate end at the joint through a rigidity matrix method; the monitoring signals of the plurality of dowel bars with the FBGs arranged can reflect the approximately slab staggering deformation conditions of two adjacent plates at the joint to be detected, including slab staggering deformation and slab staggering deformation forms.
The shallow groove on the surface of the force transmission rod is a shallow groove which is not more than 1/4 in width and not more than 1/6 in depth along the length direction of the force transmission rod, and the bottom of the groove needs to be flat and smooth.
The FBG arrangement mode in the dowel bar shallow groove is as follows: at least 5 FBGs are arranged in a shallow groove in the dowel bar, wherein 4 FBGs for strain sensing are symmetrically arranged along the middle position of the dowel bar on two sides, the distance between every two FBGs in the four FBGs does not exceed 1/50 of the length of the dowel bar, and the four strain sensing FBGs can be connected in series to form a sensing optical fiber. The temperature sensing FBG can be arranged at any position in the shallow groove of the force transmission rod, the strain value on the force transmission rod close to the joint is relatively large, and in order to obtain a relatively obvious FBG signal, the strain FBG is arranged close to the joint.
The FBG is fixed in the shallow groove of the dowel bar in the following mode: the optic fibre among the sensing FBG of meeting an emergency is carved the section part and is closely pasted at recess bottom surface with AB glue, and temperature sensing FBG needs the sheath that a diameter is greater than optic fibre of overcoat, and this sheath is pasted in dowel bar shallow groove bottom with AB glue, carves the grating of temperature sensing FBG and writes section part and freely places in the sheath, and temperature sensing FBG tail optical fiber part is pasted at dowel bar shallow groove bottom surface with AB glue.
The FBG-dowel bar packaging mode is as follows: and filling the residual space in the shallow groove of the dowel bar with epoxy resin.
And fusing tail fibers of all FBGs embedded into the shallow grooves with jumper wires about 5cm close to the end parts of the dowel bars, and fixing the jumper wire parts extending into the shallow grooves of the dowel bars in the shallow grooves by using 502 glue. And a jumper wire leading-out road surface in the leading-out dowel bar is connected into an FBG (fiber Bragg Grating) demodulator in the monitoring station.
Based on the system, the application also provides a method for monitoring the dislocation of the seam structure of the airport pavement, which comprises the following steps:
firstly, acquiring monitoring data: and embedding the dowel bar with the FBG into a joint structure k needing to carry out dislocation deformation monitoring, and acquiring an optical signal from an FBG demodulator in a monitoring station after monitoring for a certain time.
Secondly, monitoring signal classification: the seam structure, the respective embedded dowel bar with FBGs arranged therein, and the respective strain sensing FBGs and the respective temperature sensing FBGs are labeled, as follows: the strain sensing FBG at position a on the ith dowel bar buried in the k-joint, is noted as: kiAε. Setting the tested joint structure k into a single file folder, wherein the file folder comprises i sub-files, and i is that the dowel bar with the FBG arranged in the tested joint structure is arrangedThe number, record should have the signal of strain sensing FBG and temperature sensing FBG on the dowel steel that the FBG had been arranged in every subfile, the systematic categorised monitoring signal is convenient for look for correspondingly.
Thirdly, calculating the strain of the dowel bar: and subtracting the wavelength drift value of the temperature sensing optical fiber in the dowel bar with the FBGs from the wavelength drift value of the FBGs subjected to strain sensing to obtain a wavelength drift value caused by strain of the dowel bar, and calculating the strain magnitude or temperature of each FBG through the temperature and strain coefficient produced by a manufacturer.
Fourthly, calculating the shearing force of the dowel bar at the joint and the bending moment of the plate ends at two sides of the joint: for the strain magnitude sensed by 4 strain sensing FBGs (fiber Bragg gratings) on a certain force transmission rod i, the following quaternary equation system formula is utilized to solve the shearing force P transmitted by the certain force transmission rod and the bending moment M of the plate ends on two sides of the joint by combining the Cisco theory of iron wood1、M2And seam center position h0These four unknowns:
in the formula, h1、h2、h3、h4The arrangement positions of the four strain sensing FBGs in the dowel bar are respectively; l is the length of the force transmission rod; t is the seam width; k is a dowel bar reflecting modulus; beta is the relative rigidity of the dowel bar relative to the concrete; e is the elastic modulus of the dowel bar; and I is the moment of inertia of the dowel bar.
Calculating the deflection of the plate end at the joint dowel bar by calculating the related parameter P, M obtained by calculating a certain dowel bar in the fourth stepi(i ═ 1,2) the plate end vertical deformation at the dowel is calculated in the following equation
Size:
in the formula (I), the compound is shown in the specification,
is the vertical deformation of the dowel bar at the plate end of the joint, delta0The difference between the vertical deflection values of the dowel bars and the concrete slabs at the end surfaces of the concrete slabs at the two sides of the joint is shown.
Wherein S ═ sh β L, C ═ ch β L, S ═ sin β L, and C ═ cos β L
And a sixth step: analyzing the dislocation deformation condition of the joint: for a certain monitored joint k, summarizing a plate end vertical deformation amount omega calculated by a dowel bar n (n is 1,2, 3.) of a detected region, wherein the dowel bar n is provided with an FBG (fiber Bragg Grating)k1， ωk2...,ωknAnd establishing a staggered platform form model at the joint k through the deformation of the plate ends at the positions of the plurality of dowel bars.
Compared with the prior art, the system and the method for monitoring the dislocation of the airport pavement seam structure have the following beneficial effects:
1. traditional road surface wrong platform monitoring technology need rely on manpower to utilize ruler or set square to measure each seam, and degree of automation is low, can't measure in the whole day, and the measuring process receives environmental influence factor big, and influences airport navigation to a certain extent. The dowel bar with the FBGs is simpler to manufacture; the dowel bar with the FBG is embedded in the joint structure of the airport runway, so that the joint load transfer function is realized, meanwhile, the dislocation deformation can be automatically monitored all day long, the monitoring process is hardly influenced by the environment, and zero interference is realized on airport navigation.
2. The outside wrong platform deflection of joint concrete road panel can only be measured to artifical monitoring, and the dowel steel that has arranged FBG can reflect the deformation condition of wrong platform through the dowel steel atress deformation condition in the joint structure, be one from "inside" to the reflection process of "outer", therefore, through the monitoring signal of the dowel steel that has arranged FBG, not only can calculate the size of wrong platform deformation of joint, can also know the inside change condition of joint structure, thereby just can in time discover and take the remedial measure when wrong platform early produces.
3. The invention can also be designed according to the self-monitoring requirement of civil aviation airports: can add the early warning function on dowel steel signal conversion basis, when seam crossing wrong platform deflection reached the certain degree, the dowel steel that has arranged FBG can send the early warning through monitoring signal to joint structure wrong platform deformation just can control when early production, prevents that the disease from further expanding.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the present invention will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a structural appearance view of a dowel bar with FBGs arranged therein;
FIG. 2 is a schematic representation of a dowel bar with FBGs deployed in an actual joint configuration;
fig. 3 is a concrete slab joint model containing 3 dowel bars with FBGs arranged;
FIG. 4 is a layout of FBGs on a dowel bar;
FIG. 5 is a comparison of the slab end misfit reflected by calculated and measured values;
reference numbers in the figures: 1-dowel bar, 2-shallow groove, 3-epoxy filler, 4-strain sensing FBG, 5-temperature sensing FBG, 6-sheath, 7-jumper wire, 8-seam structure, 9-FBG demodulation instrument, 10-computer terminal, 11-asphalt, 12-dowel bar with FBG arranged.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without any inventive step, are within the scope of the present invention.
Example 1
This embodiment is for being applicable to airport pavement seam structure wrong platform monitoring system, monitoring system includes: a power transmission rod and an FBG, wherein,
the dowel bar is arranged in a joint where dislocation monitoring is needed,
the FBGs are arranged in the dowel bar and are divided into a dowel bar strain FBG and a temperature monitoring FBG, and the temperature monitoring FBG of the dowel bar strain FBG is used for temperature compensation treatment;
according to the sinkholderia theory, the bending moment and the shearing force transmitted by the dowel bar are obtained through the strain magnitude monitored by the FBG, and the FBG monitoring signals are further converted into the vertical deformation magnitude of the plate end at the joint through calculation and deduction; the form of dislocation of the tested area at the joint of two adjacent boards can be reflected by a plurality of FBG-dowel bar monitoring signals.
The monitoring system comprises a plurality of dowel bars which are provided with FBGs, the positions of the dowel bars are arranged, and the distances among the dowel bars are arranged in a tested area according to the < airport concrete pavement design specification >.
At least 5 shallow grooves are formed in each dowel bar and comprise at least 4 dowel bar strain FBGs and 1 temperature monitoring FBG; the temperature monitoring FBG is located on the dowel bar, close to the central line of the dowel bar and adhered to the bottom surface of the shallow groove, and the temperature monitoring FBG is not influenced by the deformation of the dowel bar due to the fact that the sleeve is additionally arranged on the grating writing section of the temperature monitoring FBG.
The shallow groove is a groove which is formed in the surface of the dowel bar along the length direction, the width of the groove is not more than the diameter 1/4 of the dowel bar, the depth of the groove is not more than the diameter 1/6 of the dowel bar, and the bottom of the shallow groove is flat and smooth.
Fusing tail fibers of all FBGs embedded into the shallow grooves with jumper wires at positions 5cm close to the end parts of the dowel bars, and fixing the jumper wires extending into the shallow grooves of the dowel bars in the shallow grooves; and a jumper wire leading-out road surface in the leading-out dowel bar is connected into an FBG (fiber Bragg Grating) demodulator in the monitoring station.
The dowel bar strain FBG takes the middle position of the dowel bar as an axis and is symmetrically arranged on two sides of the axis; the distance between every 2 dowel bar strain FBGs does not exceed 1/50 of the length of the dowel bar, and 4 dowel bar strain FBGs are connected in series to form a sensing optical fiber;
the temperature sensing FBG is independently arranged at any position in the shallow groove of the dowel bar.
The FBG-dowel bar manufacturing and embedding steps are as follows:
the method comprises the steps of firstly, determining the diameter size, the length and the arrangement position and the interval of a dowel bar with FBGs (fiber Bragg Grating) according to the requirements of a civil aviation airport on related parameters of a joint structure.
And secondly, the shallow groove on the surface of the force transmission rod is a shallow groove 2 which is provided with a width not more than the diameter 1/4 of the force transmission rod and a depth not more than the diameter 1/6 of the force transmission rod along the length direction of the force transmission rod, and the bottom of the groove needs to be flat and smooth.
Secondly, the FBG arrangement mode in the shallow groove of the dowel bar is as follows: at least five FBGs are arranged in a shallow groove in the dowel bar, wherein 4 FBGs for strain sensing are symmetrically arranged along the two sides of the midline position of the dowel bar, the distance between every two FBGs in the four FBGs does not exceed 1/50 of the length of the dowel bar, and the four strain sensing FBGs can be connected in series to form a sensing optical fiber. The temperature sensing FBG can be arranged independently at any position in the shallow groove of the dowel bar.
Thirdly, the FBG is fixed in the shallow groove of the dowel bar in the following mode: the optical fiber among the strain sensing FBG carves the section part and closely pastes at recess bottom surface with AB glue, and temperature sensing FBG needs a diameter of overcoat to be greater than the sheath 6 of optic fibre, and this sheath is pasted in dowel steel shallow groove bottom with AB glue, carves the section part with the grating of temperature sensing FBG and freely places in the sheath, and temperature sensing FBG tail optical fiber part is pasted at dowel steel shallow groove bottom surface with AB glue, as shown in FIG. 1.
Step four, arranging the dowel bar packaging mode of FBG as follows: and filling the residual space in the shallow groove of the dowel bar with epoxy resin 3.
And fifthly, welding all tail fibers of the FBGs embedded in the shallow grooves with jumper wires 7 at about 5cm close to the end parts of the dowel bars, and fixing jumper wire parts extending into the shallow grooves of the dowel bars in the shallow grooves by using 502 glue. The jumper leading-out road surface in the leading-out force transmission rod is connected into an FBG demodulator 9 in the monitoring station, and the demodulator is connected with a computer terminal 10, as shown in figure 2.
Example 2
Based on the monitoring system provided by embodiment 1, this embodiment is a method for monitoring the dislocation of the joint structure of the airport pavement, the dowel bar1 embedded in the joint to be monitored and provided with the FBGs is deformed by dislocation to generate FBG monitoring signals, and the strain monitoring values on the dowel bar provided with the FBGs are converted into the vertical deformation of the two side plate ends of the joint by a signal conversion method, so as to reflect the deformation form of dislocation of the joint.
The method comprises the following specific steps:
acquiring monitoring data: and embedding the dowel bar with the FBG into a joint structure needing to carry out slab staggering deformation monitoring, and acquiring an optical signal from an FBG demodulator in a monitoring station after monitoring for a certain time.
And (3) monitoring signal classification: the seam structure k, the respectively embedded dowel bars with FBGs arranged thereon, and the respectively strain-sensing FBGs and the respectively temperature-sensing FBGs are labeled, as follows: the strain sensing FBG at position a on the ith dowel bar embedded in the joint, is noted as: kiAε. Each tested joint structureSet up solitary folder, this folder contains i sub-files, and i sets up the number of arranging FBG's dowel steel for being surveyed in the seam structure, records the signal of sensing FBG and temperature sensing FBG on should arranging FBG's dowel steel in every sub-file, and systematic ground classification monitoring signal is convenient for look for correspondingly.
And (3) carrying out strain calculation processing on the dowel bars: and subtracting the wavelength drift value of the temperature sensing optical fiber in the dowel bar with the FBGs from the wavelength drift value of the FBGs subjected to strain sensing to obtain a wavelength drift value caused by strain of the dowel bar, and calculating the strain magnitude or temperature of each FBG through the temperature and strain coefficient produced by a manufacturer.
The step of converting the dowel bar monitoring signal with the FBG into the joint structure slab staggering deformation size is as follows:
calculating the shearing force of a dowel bar at the joint and the bending moment of the plate ends at two sides of the joint: for the strain magnitude sensed by 4 strain sensing FBGs (fiber Bragg gratings) on a certain dowel bar, based on the Chouchi classical theory of iron wood, the following quaternary equation system formula is utilized to solve the shearing force P transmitted by the certain dowel bar, and the bending moment M of the plate ends on two sides of the joint1、M2And seam center position h0These four unknowns:
in the formula, h1、h2、h3、h4Four FBG (fiber Bragg Grating) force-transmitting rods for sensing strain respectivelyIn which h is1，h2The bending moment of the corresponding FBG arrangement position at the plate end is M1One side of (a); h is3，h4The bending moment of the corresponding FBG arrangement position at the plate end is M2One side of (a); l is the length of the force transmission rod; t is the seam width; k is the reflection modulus of the dowel bar; beta is the relative rigidity of the dowel bar relative to the concrete; e is the elastic modulus of the dowel bar; and I is the section moment of inertia of the dowel bar.
Calculating the deflection of the single plate end at the joint dowel bar, namely calculating a relevant parameter P, M obtained by calculating a certain dowel bar in the fourth stepi(i ═ 1,2) the plate end vertical deformation at the dowel was calculated in the following equation
Size:
in the formula (I), the compound is shown in the specification,
is the vertical deformation of the dowel bar at the plate end of the joint, delta0The difference between the vertical deflection values of the dowel bars and the concrete slabs at the end surfaces of the concrete slabs at the two sides of the joint is shown.
Wherein S is sh β L, C is ch β L, S is sin β L, and C is cos β L.
The vertical deformation size of the single board end of the joint structure obtained through the transmission rod monitoring signal conversion arranged with the FBG reflects the mode of the dislocation deformation condition of a certain fast path panel in the detected area as follows:
first step ofAnd analyzing the dislocation deformation condition of the joint: for a certain monitored joint k, summarizing the vertical deformation omega of the plate end of one joint structure side plate, which is obtained by calculating the FBG signal on the dowel bar n, at the dowel bar i with the FBG arranged thereon k1，ω k2...,ωknVertical deformation amount ω 'of plate end of the other side plate at dowel bar n where FBG is arranged'k1，ω′k2...,ω′kn。
In the second step, the dislocation deformation of the joint k at the position i is | omegakn-ω′kn|。
Thirdly, through i dislocation deformation | omegak1-ω′k1|，|ωk2-ω′k2|...,|ωki-ω′kiAnd l, the slab staggering form deformation condition of the measured section of the measured seam k can be established, and the slab staggering form deformation condition comprises the vertical deformation size of the slab end and the slab staggering form. Provide data for the flatness analysis of the road surface.
Experimental case
In order to verify that the vertical deformation of the concrete slab end can be calculated through the signal of the dowel bar with the FBG arranged, and different forms of slab end slab staggering can be reflected, a static load experiment for simulating slab end slab staggering generation is designed. In this experiment, the staggering was achieved by off-center loading, with concentrated force applied at the non-midpoint of the plate edge (plate edge 1/4 location), and the plate deflected in the dowel direction to simulate a plate-side-flipped staggering pattern.
Further, according to the < specification of airport cement concrete pavement design >, one end of the dowel bars is coated with asphalt and arranged in a staggered manner at the joints, and therefore, the present experiment embeds three dowel bars with FBGs arranged therein in a concrete slab to satisfy the requirements for the staggered arrangement in the < specification > experiment. Because each loading form causes the internal stress of the dowel bar and the concrete to change, in order to eliminate the influence, three identical experimental loading models are manufactured in the experiment, the loading models are identical, and as shown in fig. 3, the shadow part of the dowel bar with the FBG arranged in the graph is wrapped by asphalt. The lower part of the concrete slab is provided with an industrial damping rubber pad simulation elastic foundation. The FBG arrangement on the dowel bar is shown in fig. 4. The experimental model was placed on a two-way loading bench as shown in fig. 4, and by increasing the amount of load applied to the panel edges, the deformation of the panel ends was incrementally changed accordingly. For the deformation of accurate measurement board end, this experiment was placed 6 percentage table respectively in the concrete tip position department of three dowel bars that have arranged FBG in the seam both sides.
The physical and geometrical parameters involved in this experiment were: strain coefficient η of FBGε1.2 pm/. mu.epsilon., temperature coefficient eta of the fiber gratingT1.2 pm/. mu.epsilon.the modulus of elasticity E of the force-transmitting rod is 2.0X 105N/mm2The length L of the transmission rod is 50cm, the diameter d of the transmission rod is 3cm, and the foundation bed reaction coefficient K of the concretes＝1.2×1010N/m3The width w of the seam is 10 mm.
Table 1 reflects the vertical deformation values of the plate ends of the left and right side plates at the joint calculated by the signal conversion method and the vertical deformation values measured by the dial gauge as the load increases:
TABLE 1
Two graphs in fig. 5 respectively show the slab end staggering form reflected by the calculated value and the measured value, and the graph on the left side reflects that the vertical deformation value calculated by the concrete slab end through the signal conversion method and the measured value have the same increasing trend that the vertical deformation value is increased along with the increase of the load. Since the concentrated load is applied to the position of the plate edge deviating from the midpoint, the concrete plate end will turn over and tip over, which can be observed from the vertical deformation value of the plate end on the monitoring signals of the three FBG-dowel bars in the right graph. Since the concentrated load is applied to the middle position between FBG-dowel bar1 and FBG-dowel bar2, the deformation value of the plate end at FBG-dowel bar1 position is the largest, and the deformation value of the plate end at FBG-dowel bar3 position is the smallest. In addition, the difference value of the calculated deformation value and the measured deformation value of the two sides of the joint under the same load is small, because the load transmission capacity of the joint structure of the tested model is good, although concentrated load is only applied to the concrete plate end on one side of the joint, the load on the side is basically evenly distributed to the adjacent plates through the force transmission rods, and the vertical deformation values of the concrete plates on the two sides are similar.
From the graph, we can find that the calculated deformation value is larger than the measured value, and the difference value between the calculated deformation value and the measured value is increased along with the increase of the load, because the FBG embedded in the dowel bar is adhered to the surface of the dowel bar, because the adhesion layer is thin, when the dowel bar is bent greatly, the FBG is separated from the adhesion layer, and the epoxy resin can generate relative sliding with the steel bar when the steel bar is bent, the generated sliding can add extra horizontal shearing force to the separated FBG, so that the axial strain of the FBG is increased, and under the condition of larger load, the bending degree of the dowel bar is larger, the relative sliding between the epoxy resin and the steel bar is larger, so that the axial stress change of the FBG is larger. Therefore, in the signal processing, the deviation of the strain is a main cause that eventually causes an error from the calculation result.
The experiment proves that the method is feasible, namely, the FBGs are arranged on the dowel bars at the joint structure for slab staggering monitoring, and the slab staggering deformation size and the slab staggering form of the tested area of the concrete slab can be reflected through a corresponding monitoring signal conversion method. Compared with the traditional runway dislocation detection means, the dowel steel dislocation monitoring technology with the FBGs does not need manual measurement by a ruler point by point, does not influence navigation, can monitor dislocation change in real time and continuously, and can find diseases in the initial stage of dislocation generation. And the method has important significance for expanding the application field of the optical fiber sensing technology and enriching the product design of the optical fiber sensor.
The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (10)
1. Be applicable to airport pavement seam structure wrong platform monitoring system, its characterized in that, monitoring system includes: a dowel and several FBGs, of which,
the dowel bar is arranged in a joint where dislocation monitoring is needed,
the FBGs are arranged in the dowel bar and are divided into a dowel bar strain FBG and a temperature monitoring FBG, and the temperature monitoring FBG of the dowel bar strain FBG is used for temperature compensation treatment;
according to the sinkholderia theory, the bending moment and the shearing force transmitted by the force transmission rod are obtained through the strain magnitude monitored by the FBG, and the FBG monitoring signals are converted into the vertical deformation magnitude of the plate end at the joint through the obtained bending moment and shearing force; the monitoring signals of the FBGs on the plurality of dowel bars reflect the dislocation form of the tested area at the joint of the two adjacent plates.
2. The system for monitoring the dislocation of the airport pavement joint structure according to claim 1, wherein the dowel bars with the FBGs are arranged at the joint of the concrete slab, and the spacing and the like are arranged in the tested area according to the airport pavement concrete design specifications.
3. The system for monitoring the dislocation of the airport pavement seam structure according to claim 2, wherein each dowel bar is provided with at least 5 shallow grooves containing at least 4 dowel bar strain FBGs and 1 temperature monitoring FBG; the temperature monitoring FBG is located on the dowel bar, close to the central line of the dowel bar and adhered to the bottom surface of the shallow groove, and the temperature monitoring FBG is not influenced by the deformation of the dowel bar due to the fact that the sleeve is additionally arranged on the grating writing section of the temperature monitoring FBG.
4. The system of claim 2, wherein the shallow groove is a groove with a width not greater than a dowel diameter 1/4 and a depth not greater than a dowel diameter 1/6, and is formed on the surface of the dowel along the length direction of the dowel, and the bottom of the shallow groove is flat and smooth.
5. The system for monitoring the dislocation of the airport pavement seam structure according to claim 4, wherein all the FBGs embedded in the shallow groove are welded with the jumper at a position 5cm close to the end of the dowel bar, and the jumper part extending into the shallow groove of the dowel bar is fixed in the shallow groove; and a jumper wire leading-out road surface in the leading-out dowel bar is connected into an FBG (fiber Bragg Grating) demodulator in the monitoring station.
6. The system for monitoring the dislocation of the airport pavement seam structure according to any one of claims 1 to 5, wherein the dowel strain FBG is arranged symmetrically on two sides of an axis which is the middle position of the dowel; the distance between every 2 dowel bar strain FBGs does not exceed 1/50 of the length of the dowel bar, and 4 dowel bar strain FBGs are connected in series to form a sensing optical fiber;
the temperature sensing FBG is independently arranged at any position in the shallow groove of the dowel bar.
7. Method for monitoring the dislocation of a seam structure of an airport pavement, characterized in that it is based on a monitoring system according to claim 1, comprising the following steps:
the first step is as follows: acquiring monitoring data: embedding the monitoring system into a joint structure needing dislocation deformation monitoring, and obtaining an optical signal from an FBG demodulator;
the second step is that: and (3) carrying out strain calculation processing on the dowel bars: calculating the strain magnitude or temperature of each FBG according to the FBG monitoring signal, the temperature and the strain coefficient of the FBG;
the third step: calculating the shearing force of a dowel bar at the joint and the bending moment of the plate ends at two sides of the joint by combining the Cisco theory of ironwood;
the fourth step: and according to the related parameters obtained by calculation of a certain dowel bar in the third step, calculating the vertical deformation of the plate end at the dowel bar:
the fifth step: analyzing the dislocation deformation condition of the joint: for a certain monitored joint k, summarizing a board end vertical deformation amount omega obtained by calculating n (n is 1,2, 3.) FBG monitoring signals in a monitoring system of a detected areak1，ωk2...,ωknAnd establishing a staggered platform form model at the joint k through the deformation of the plate ends at the positions of a plurality of dowel bars, and evaluating the joint of the tested areaAnd (5) avoiding the platform deformation condition.
8. The method for monitoring the dislocation of the seam structure of the airport pavement according to claim 7, wherein the third step is specifically as follows:
for the strain magnitude sensed by the strain FBGs (fiber Bragg gratings) of 4 dowel bars on any dowel bar in the monitoring system, the transfer shear magnitude P of the dowel bar is calculated by using the following formula of quaternary equationstAnd bending moment M of two side plate ends of the joint1、M2Size:
in the formula, h0The position of the middle point of the joint on the dowel bar; h is1、h2、h3、h4The arrangement positions of the 4 dowel bar strain FBGs in the dowel bars are respectively; l is the length of the force transmission rod; delta is the seam width; k is a dowel bar reflecting modulus; beta is the relative rigidity of the dowel bar relative to the concrete; e is the elastic modulus of the dowel bar; and I is the moment of inertia of the dowel bar.
9. The method for monitoring the dislocation of the seam structure of the airport pavement according to claim 7, wherein the fourth step is specifically:
the fourth step: transferring a certain force in the third stepCalculated relevant parameters P, M for the sticki(i ═ 1,2) the magnitude of the vertical deformation of the plate end at the dowel was calculated by substituting the following equation:
in the formula (I), the compound is shown in the specification,
is the vertical deformation of the dowel bar at the plate end of the joint, delta0The difference between the vertical deflection values of the dowel bar and the concrete slab at the joint is obtained; wherein, S ═ sh β L, C ═ ch β L, S ═ sin β L, and C ═ cos β L.
10. The method for monitoring the dislocation of the seam structure of the airport pavement according to claim 7, wherein the step five is specifically as follows:
step 5.1, analyzing the dislocation deformation condition of the joint: for a certain monitored joint k, summarizing the vertical deformation omega of the plate end of one joint structure side plate at the dowel bar i, which is obtained by calculating the FBG monitoring signal on the dowel bar nk1，ωk2...,ωknVertical deformation amount omega 'of plate end of the other side plate at dowel bar n'k1，ω′k2...,ω′kn；
Step 5.2, the dislocation deformation of the joint k at the position i is | omegakn-ω′kn|；
Step 5.3, through i dislocation deformation | omegak1-ω′k1|，|ωk2-ω′k2|...,|ωki-ω′kiAnd establishing the slab staggering form deformation condition of the detected section of the detected joint k, including the vertical deformation size of the plate end and the slab staggering deformation form, and providing data for the pavement flatness analysis.
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