CN112066945A - Airport roadbed settlement monitoring structure and method based on distributed optical fiber embedding - Google Patents

Airport roadbed settlement monitoring structure and method based on distributed optical fiber embedding Download PDF

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Publication number
CN112066945A
CN112066945A CN202010928321.3A CN202010928321A CN112066945A CN 112066945 A CN112066945 A CN 112066945A CN 202010928321 A CN202010928321 A CN 202010928321A CN 112066945 A CN112066945 A CN 112066945A
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settlement
airport
optical fiber
cable
measuring instrument
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凌建明
方意心
石蓉
王增逸
张家科
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Sichuan Airport Group Co ltd
Tongji University
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Sichuan Airport Group Co ltd
Tongji University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C5/00—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D33/00—Testing foundations or foundation structures
    • 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
    • G01B11/18—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge using photoelastic elements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D3/00—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups
    • G01D3/028—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure
    • G01D3/036—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure on measuring arrangements themselves

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Abstract

The invention relates to the field of road engineering, in particular to a distributed optical fiber embedding-based airport roadbed settlement monitoring structure and method. The airport roadbed settlement monitoring structure based on distributed optical fiber embedding comprises an airport pavement, wherein the airport pavement comprises a pavement layer and a roadbed layer, an airport roadbed settlement monitoring system is arranged in the roadbed layer, the airport roadbed settlement monitoring system comprises a temperature compensation optical cable, a metal-based cable-shaped optical cable, an integral settlement measuring instrument and a single-point settlement measuring instrument, the extending directions of the temperature compensation optical cable, the metal-based cable-shaped optical cable and the integral settlement measuring instrument are consistent, the single-point settlement measuring instrument is positioned in the extending direction of the integral settlement measuring instrument, the metal-based cable-shaped optical cable extends linearly, and the temperature compensation optical cable extends nonlinearly. The airport roadbed settlement monitoring structure based on distributed optical fiber embedding realizes remote, lossless, anti-interference, continuity and intelligent monitoring of roadbed settlement.

Description

Airport roadbed settlement monitoring structure and method based on distributed optical fiber embedding
Technical Field
The invention relates to the field of road engineering, in particular to a distributed optical fiber embedding-based airport roadbed settlement monitoring structure and method.
Background
In airport engineering, the settlement of the roadbed needs to be monitored so as to prevent the runway structure from being damaged due to excessive differential settlement and endanger the safety and smoothness of taking off and landing of an airplane and the long-term durability of airport facilities. The foundation settlement monitoring mainly includes that monitoring instruments are buried in each layer of a foundation, settlement deformation of the foundation is obtained according to actually measured data, and the future development trend is predicted. At present, the main methods for monitoring foundation settlement include a settlement plate method, a leveling method, a monitoring pile method and the like. Most of the traditional settlement monitoring methods are point-type monitoring, errors exist in 'point-to-surface' monitoring, the settlement condition of the foundation is difficult to represent comprehensively and effectively, and the problems of large field workload, low automation level, complex burying scheme, easiness in interference in construction and the like exist. The research and development of a large-range, automatic, real-time and high-precision monitoring method for foundation settlement in a working area is urgent.
The distributed optical fiber is used as a novel sensing material, not only is a sensing medium, but also is a transmission channel, has obvious advantages in working environments with variable climatic conditions and complex geological conditions compared with other traditional sensing materials, and can realize remote, lossless, anti-interference, continuity and intelligent monitoring. By monitoring the change of the Brillouin scattering light frequency in the distributed optical fiber, the strain of the part to be measured can be determined and the deformation can be calculated, so that the large-scale automatic monitoring of the foundation settlement can be realized. At present, in the application of foundation settlement monitoring, distributed optical fiber mainly adopts the mode of vertical stretching (direct burial), though can carry out comparatively accurate monitoring to the foundation layered settlement of burying the position underground, nevertheless from the planar dimension who subsides the region that awaits measuring, still belongs to the category of point type monitoring. The transverse embedding of the distributed optical fiber lacks a strain-displacement analysis method, and at present, the method has no precedent of being widely applied in engineering.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, it is an object of the present invention to provide a distributed optical fiber burying-based airport roadbed settlement monitoring structure and method, which are used for solving the problems in the prior art.
In order to achieve the above and other related objects, an aspect of the present invention provides an airport roadbed settlement monitoring structure based on distributed optical fiber burying, which includes an airport roadbed, the airport roadbed includes a pavement layer and a roadbed layer, the roadbed layer is provided with an airport roadbed settlement monitoring system, the airport roadbed settlement monitoring system includes a temperature compensation optical cable, a metal-based cable, an integral settlement measuring instrument and a single-point settlement measuring instrument, the temperature compensation optical cable, the metal-based cable and the integral settlement measuring instrument extend in the same direction, the single-point settlement measuring instrument is located in the extending direction of the integral settlement measuring instrument, the metal-based cable extends linearly, and the temperature compensation optical cable extends non-linearly.
In some embodiments of the invention, a plurality of airport roadbed settlement monitoring systems are disposed in the roadbed layer.
In some embodiments of the invention, the temperature compensation optical cable, the metal-based cable and the integral settlement gauge are all buried in the transverse direction according to the extending direction of the airport runway.
In some embodiments of the invention, the airport ballast settlement monitoring system comprises a plurality of single-point settlement measuring instruments which are evenly distributed in the extension direction of the whole settlement measuring instrument.
In some embodiments of the present invention, the length of the temperature compensation optical cable is 1.05 to 1.20 times the length of the metal-based strand optical cable in a unit width of the airport pavement.
In some embodiments of the present invention, the temperature-compensated fiber optic cable includes a first fiber body and a first cable jacket surrounding the first fiber body.
In some embodiments of the present invention, a metal matrix strand optical cable includes a second fiber body and a second cable jacket surrounding the second fiber body.
In some embodiments of the invention, the temperature compensated optical cable, the metal matrix strand cable, the bulk settlement gauge and the single point settlement gauge are buried in fine sand.
In some embodiments of the invention, the temperature compensation optical cable, the metal-based funicular optical cable, the bulk settlement gauge and the single point settlement gauge are covered with backfilled undisturbed soil.
In some embodiments of the invention, the backfilled undisturbed soil is doped with bentonite.
In some embodiments of the present invention, the optical fiber cable further comprises BOTDR distributed sensors respectively connected to the optical fibers in the optical fiber cable.
The invention provides a method for monitoring the settlement of an airport roadbed based on distributed optical fiber embedding, which monitors the settlement of the airport roadbed by the structure for monitoring the settlement of the airport roadbed based on distributed optical fiber embedding and comprises the following steps:
obtaining the estimated actual strain by calculation according to the formula (1)
Figure BDA0002669256090000021
Figure BDA0002669256090000022
Wherein the content of the first and second substances,
Figure BDA0002669256090000023
is the average strain;
(x) Is the difference value of the strain quantity of the metal-based cable-shaped optical cable (22) and the strain quantity of the temperature compensation optical cable (21), and x belongs to [0, l ];
alpha is a strain reduction coefficient and represents the relaxation degree of the optical fiber;
beta is a standard deviation coefficient and represents the redistribution of the internal strain of the optical fiber;
determining the maximum sedimentation position according to equation (2), where the zero point x of the function y (x) is x0Namely the maximum sedimentation position:
Figure BDA0002669256090000024
wherein the content of the first and second substances,
Figure BDA0002669256090000031
Figure BDA0002669256090000032
obtaining the estimated displacement by calculation according to the formula (5)
Figure BDA0002669256090000033
Figure BDA0002669256090000034
Thereby obtaining the relative settlement distance of the airport pavement base.
In some embodiments of the invention, the strain reduction factor α is the total fiber elongation Δ lAnd the ratio of the strain reduction coefficient alpha to the actual total elongation delta l of the optical fiber is 0.9-1.0.
In some embodiments of the present invention, the standard deviation factor β is 0.2 to 1.0.
In some embodiments of the present invention, the standard deviation coefficient β is calculated by equation (3):
Figure BDA0002669256090000039
in some embodiments of the invention, the integral settlement distance of the airport runway foundation is obtained from the sum of the relative settlement distance and the absolute settlement distance, which is measured by the integral settlement gauge (23) and the single-point settlement gauge (24).
Another aspect of the present invention provides a computer-readable storage medium, on which a computer program is stored, which when executed by a processor, implements the steps of the above-mentioned distributed optical fiber burying-based airport roadbed settlement monitoring method.
In another aspect, the invention provides an apparatus comprising: a processor and a memory, the memory being configured to store a computer program, the processor being configured to execute the computer program stored by the memory to cause the apparatus to perform the steps of the above-described distributed optical fiber burying-based airport roadbed settlement monitoring method.
Another aspect of the present invention provides an apparatus, which may include:
estimating actual strain
Figure BDA0002669256090000035
A calculation module for calculating and obtaining the estimated actual strain according to the formula (1)
Figure BDA0002669256090000036
Figure BDA0002669256090000037
Wherein the content of the first and second substances,
Figure BDA0002669256090000038
is the average strain;
(x) Is the difference value of the strain quantity of the metal-based cable-shaped optical cable (22) and the strain quantity of the temperature compensation optical cable (21), and x belongs to [0, l ];
alpha is a strain reduction coefficient and represents the relaxation degree of the optical fiber;
beta is a standard deviation coefficient and represents the redistribution of the internal strain of the optical fiber;
maximum sedimentationA position calculation module for determining the maximum settlement position according to equation (2), where x is the zero point of function y (x)0Namely the maximum sedimentation position:
Figure BDA0002669256090000041
wherein the content of the first and second substances,
Figure BDA0002669256090000042
Figure BDA0002669256090000043
estimate displacement
Figure BDA0002669256090000044
A calculation module for calculating and obtaining the estimated displacement according to the formula (5)
Figure BDA0002669256090000045
Figure BDA0002669256090000046
Optionally, the system further comprises an overall settlement distance calculation module, configured to obtain an overall settlement distance of the airport runway foundation according to a sum of the relative settlement distance and the absolute settlement distance.
Drawings
Fig. 1(a) is a schematic view of the airport ballast settlement monitoring structure of the present invention in the case of no settlement.
Fig. 1(b) is a schematic diagram showing the airport roadbed settlement monitoring structure of the present invention in the case of settlement.
Fig. 2 shows a schematic diagram of the distributed fiber optic measurement principle of BOTDR.
FIG. 3 is a schematic diagram illustrating the calculation of the strain and vertical displacement of the optical fiber according to the present invention.
Fig. 4 is a schematic diagram showing an analytical relationship between optical fiber strain and vertical displacement based on a calibration test in the embodiment of the present invention.
FIG. 5 is a schematic diagram of a back calculation of fiber strain based settling in an embodiment of the present invention.
FIG. 6 is a schematic diagram of a roadbed settlement monitoring cloud in the embodiment of the invention.
FIG. 7 shows the monitoring data and the correction result of roadbed subsidence according to the embodiment of the present invention.
Description of the element reference numerals
1 airport pavement
11 pavement layer
12 base layers
2 airport roadbed settlement monitoring system
21 temperature compensation optical cable
22 metal-based cable-like optical cable
23 integral settlement measuring instrument
24 single point settlement measuring instrument
25 optical fiber demodulator
Detailed Description
The invention provides a distributed optical fiber embedding-based airport roadbed settlement monitoring structure and a distributed optical fiber embedding-based airport roadbed settlement monitoring method through a large amount of practical researches.
The invention provides an airport pavement settlement monitoring structure based on distributed optical fiber burying, as shown in fig. 1(a) and 1(b), comprising an airport pavement 1, wherein the airport pavement 1 comprises a pavement layer 11 and a pavement base layer 12, an airport pavement settlement monitoring system 2 is arranged in the pavement base layer 12, the airport pavement settlement monitoring system 2 comprises a temperature compensation optical cable 21, a metal-based cable rope 22, a bulk settlement measuring instrument 23 and a single-point settlement measuring instrument 24, the temperature compensation optical cable 21, the metal-based cable rope 22 and the bulk settlement measuring instrument 23 extend in the same direction, the single-point settlement measuring instrument 24 is positioned in the extending direction of the bulk settlement measuring instrument 23, the metal-based cable rope 22 extends in a straight line, and the temperature compensation optical cable 21 extends in a non-straight line. The pavement layer 11 of the airport pavement 1 may further include a surface layer, a base layer, and a cushion layer, the airport pavement settlement monitoring system 2 is usually located in the pavement base layer 12, the linear extension generally refers to that the metal-based cable 22 can apply a certain pre-stress to both ends of the optical fiber when buried, so that the optical fiber is in a stretched state, so that the optical fiber can be linearly extended in the pavement base layer 12, so as to realize effective sensing of the tiny vertical deformation (as shown by the arrow direction in fig. 1 (b)), and the non-linear extension generally refers to that the temperature compensation cable 21 is in a relaxed non-stretched state when buried (for example, in the airport pavement 1 with unit width, the length of the temperature compensation cable 21 is 1.05 to 1.20 times of the length of the metal-based cable 22), so that the temperature compensation cable 21 can be non-linearly extended in the base layer 12, and the temperature compensation cable 21 in the relaxed state has no sensing of the tiny vertical deformation, only the strain amount caused by the temperature change is measured, and the measured strain amount of the optical fiber can be used for correcting the measured strain amount of the optical fiber of the metal based funicular cable 22 extending in a straight line, and further calculating and obtaining the relative settlement distance of the measuring point in the airport runway foundation relative to the airport runway foundation, the single-point settlement gauge 24 is located in the extending direction of the integral settlement gauge 23, the single-point settlement gauge 24 can obtain the settlement distance of the airport pavement base of a specific measuring point, and the relative differences from each location on the airport runway base itself with respect to the above-mentioned specific measuring points can be obtained from the integral settlement measuring instruments 23, thereby determining the settlement distance of the airport pavement base per se and the settlement distance of the measuring point relative to the original pavement can be obtained according to the relative settlement distance of the measuring point relative to the airport pavement base obtained by calculation.
In the airport pavement settlement monitoring structure based on distributed optical fiber burying, the distances between the temperature compensation optical cable 21, the metal-based cable-like optical cable 22, the integral settlement measuring instrument 23 and the single-point settlement measuring instrument 24 are usually not too large, for example, the maximum distance between the temperature compensation optical cable 21, the metal-based cable-like optical cable 22, the integral settlement measuring instrument 23 and the single-point settlement measuring instrument 24 is usually not more than 60cm, preferably not more than 30cm, and specifically may be 5-30 cm, 5-10 cm, 10-15 cm, 15-20 cm, 20-25 cm or 25-30 cm, while the distances between the temperature compensation optical cable 21 and the metal-based cable-like optical cable 22 may be usually not more than 5cm, not more than 1cm, 1-2 cm, 2-3 cm, 3-4 cm or 4-5 cm, so as to be integrally matched, and on the premise that the extending directions are consistent, the corresponding parts to each other may perform data measurement for the same measuring area, and the reliability of data is ensured. In the whole airport pavement 1, a plurality of airport pavement settlement monitoring systems 2 can be arranged in the pavement base layer 12 so as to rapidly measure all the positions of the airport pavement 1, and the distance between the airport pavement settlement monitoring systems 2 can be 4 m-20 m, 4 m-8 m, 8 m-12 m, 12 m-16 m or 16 m-20 m according to the extending direction of the airport runway. The temperature compensation optical cable 21, the metal-based cable-like optical cable 22 and the integral settlement gauge 23 are usually laid horizontally in the extending direction of the airport runway, so as to facilitate data acquisition.
In the airport runway foundation settlement monitoring structure based on distributed optical fiber burying, the number of the single-point settlement measuring instruments 24 in the airport runway foundation settlement monitoring system 2 can be one or more, and the main function of the airport runway foundation settlement monitoring structure is to provide one or more bases for the integral settlement measuring instruments 23. The integral settlement measuring instrument 23 and the single-point settlement measuring instrument 24 are usually matched with each other, the extending directions of the integral settlement measuring instrument 23 and the single-point settlement measuring instrument 24 are usually consistent with the temperature compensation optical cable 21 and the metal-based cable-shaped optical cable 22, and the distance between the settlement measuring instruments can be usually 20-40 m, 20-25 m, 25-30 m, 30-35 m or 35-40 m, so that the settlement distance of each part of the airport runway foundation can be determined according to the measuring results of the single-point settlement measuring instrument 24 and the integral settlement measuring instrument 23.
In the airport runway foundation settlement monitoring structure based on distributed optical fiber burying provided by the invention, a person skilled in the art can select suitable optical cables as the temperature compensation optical cable 21 and the metal-based cable-like optical cable 22, for example, the temperature compensation optical cable 21 comprises a first optical fiber body and a first optical cable jacket for wrapping the first optical fiber body, the diameter of the first optical fiber body can be 0.25mm to 0.90mm, 0.25mm to 0.30mm, 0.30mm to 0.40mm, 0.40mm to 0.50mm, 0.50mm to 0.60mm, 0.60mm to 0.70mm, 0.70mm to 0.80mm, or 0.80mm to 0.90mm, the thickness of the first optical cable jacket can be 1mm to 3mm, 1mm to 1.5mm, 1.5mm to 2mm, 2mm to 2.5mm, or 2.5mm to 3mm, the metal-based cable-like optical cable 22 comprises a second optical fiber body and a second optical cable body for wrapping the second optical fiber body, and the diameter of the second optical cable body can be 0.25mm to 0.90mm, 0.25mm to 0.30mm, 0.30mm to 0.40mm, 0.40mm to 0.50mm, 0.50mm to 0.60mm, 0.60mm to 0.70mm, 0.70mm to 0.80mm, or 0.80mm to 0.90mm, and the thickness of the second optical cable jacket may be 1mm to 3mm, 1mm to 1.5mm, 1.5mm to 2mm, 2mm to 2.5mm, or 2.5mm to 3 mm.
In the airport roadbed settlement monitoring structure based on distributed optical fiber burying, the temperature compensation optical cable 21, the metal-based cable 22, the integral settlement measuring instrument 23 and the single-point settlement measuring instrument 24 can be usually buried in fine sand. The thickness of the fine sand layer can be usually 5 cm-0.5 m, 5 cm-10 cm, 10 cm-20 cm, 20 cm-40 cm, 40 cm-60 cm, 60 cm-80 cm or 80 cm-100 cm except for the jacket which is sleeved outside the optical fiber. The temperature compensation optical cable 21, the metal-based cable-shaped optical cable 22, the integral settlement measuring instrument 23 and the single-point settlement measuring instrument 24 can be covered with backfill undisturbed soil, and if the elements are buried in fine sand, the backfill undisturbed soil can be laid on the fine sand, so that the monitoring precision of the optical fiber can be ensured. The backfill soil can be in-situ soil which can be doped with a small amount of bentonite, so that the coupling effect of the distributed optical fiber and the soil matrix can be improved.
The airport roadbed settlement monitoring structure based on distributed optical fiber burying provided by the invention can further comprise BOTDR distributed sensors, wherein the BOTDR distributed sensors are usually connected with optical fibers in optical cables respectively, for example, the BOTDR distributed sensors can be connected with the first optical fiber body and the second optical fiber body respectively so as to be used for acquiring the strain quantities of the first optical fiber body and the second optical fiber body. The BOTDR distributed sensor, the integral settlement gauge 23 and the single-point settlement gauge 24 may be connected to a computer, so as to transmit the information obtained by measurement to the computer and further perform subsequent processing on the related data.
In the airport roadbed settlement monitoring structure buried by the distributed optical fibers, the monitoring principle is as follows: the distributed optical fibers buried under the condition of differential settlement are driven to cooperatively deform by the uneven settlement of the roadbed, namely, transverse stretching is generated, the Brillouin scattering frequency spectrum of the section of sampling point generates frequency drift due to the strain change generated on the optical fibers at the differential settlement, and the relationship between the Brillouin frequency shift change amount and the temperature and the strain of the optical fibers is shown as a formula (6). After the Brillouin frequency shift signal is analyzed by the demodulator, the differential settlement of the track base can be deduced and inversely calculated according to the calibration test result in the previous stage. Fig. 2 is a schematic diagram showing the principle of distributed optical fiber measurement based on the brillouin scattering optical time domain reflectometry (BOTDR).
Figure BDA0002669256090000071
In the formula, vB(, T) is the Brillouin frequency shift quantity of the distributed optical fiber when the temperature is T and the strain is changed; v. ofB(0,T0) At a temperature of T0When the strain is 0, the Brillouin frequency shift amount of the distributed optical fiber is determined;
Figure BDA0002669256090000072
the proportionality coefficients, respectively representing strain and temperature, are related to the type of optical fibre and are calibrated by the manufacturer. The method is characterized in that roadbed settlement, namely vertical displacement, is represented through axial tensile strain of the distributed optical fiber, the key technology is to analyze the correlation between optical fiber strain and displacement position, and provide basis for analyzing the optical fiber axial strain-roadbed soil settlement of the buried soil medium, and for achieving the purpose, the optical fiber strain under known vertical displacement at different positions and sizes can be obtained through a calibration test, and the corresponding relationship between the optical fiber strain and the known vertical displacement is established.
The second aspect of the present invention provides a method for monitoring settlement of an airport runway foundation based on distributed optical fiber burying, which monitors the settlement of the airport runway foundation by using the structure for monitoring settlement of the airport runway foundation based on distributed optical fiber burying, and comprises:
obtaining the estimated actual strain by calculation according to the formula (1)
Figure BDA0002669256090000073
Figure BDA0002669256090000074
Wherein the content of the first and second substances,
Figure BDA0002669256090000075
is the average strain, i.e. the average of each (x);
(x) The difference value of the strain quantity of the metal-based cable-shaped optical cable and the strain quantity of the temperature compensation optical cable is obtained, and (x) is the actual strain measurement result of the optical fiber, wherein the strain quantity of the optical fiber caused by temperature change is removed, x belongs to [0, l ], and l is the length of the optical fiber of the test section;
alpha is a strain reduction coefficient and represents the relaxation degree of the optical fiber;
beta is a standard deviation coefficient and represents the redistribution of the internal strain of the optical fiber;
determining the maximum sedimentation position according to equation (2), where the zero point x of the function y (x) is x0I.e. the maximum sedimentation position, since for the maximum sedimentation position x0The amount of strain is 0 to x0And x0The values obtained by integration in the two sections should be substantially the same:
Figure BDA0002669256090000081
wherein the content of the first and second substances,
Figure BDA0002669256090000082
Figure BDA0002669256090000083
if a certain point on the optical fiber is vertically displaced, as shown in fig. 3, the position coordinate of the point A is set as x, a infinitesimal dx on the optical fiber is taken, and the original optical fiber AB section is deformed into an A ' B ' section, so according to the pythagorean theorem and the strain definition, the vertical displacement y (x) of each point is the integral of y ' (x) from the end point to the point, and the formula (3) and the formula (4) can be obtained in a unidirectional deformation region according to the least favorable settlement;
obtaining the estimated displacement by calculation according to the formula (5)
Figure BDA0002669256090000084
Figure BDA0002669256090000085
Estimate displacement
Figure BDA0002669256090000086
The relative settlement of each point of the airport pavement base in the extension direction of the airport pavement base settlement monitoring system can be represented.
In the airport roadbed settlement monitoring method based on distributed optical fiber burying, alpha is related to the property and the state of the optical fiber, and the value of the alpha of the used optical fiber can be obtained through pre-experimental measurement. The strain reduction coefficient alpha can be calculated by the total elongation delta l of the optical fiber based on the measured dataThe ratio of the total elongation Δ l of the optical fiber to the actual total elongation Δ l of the optical fiber is measured, and thus the degree of relaxation of the optical fiber can be characterized. In a specific embodiment of the present invention, the optical fiber cable used in the monitoring system may be fixed at two ends, suspended in the middle, and subjected to known deformation in a laboratory, and the strain amount of the optical fiber may be measured by the BOTDR distributed sensor connected to the optical fiber, and the total elongation Δ l of the optical fiber may be obtained by calculation according to the strain amountMeanwhile, the actual total elongation delta l of the optical fiber is monitored, so that the strain reduction coefficient alpha of the optical fiber is calculated and obtained. Then in the calculation of the monitoring of the specific project,the value of the strain reduction coefficient α may be used. The strain reduction coefficient alpha can be generally 0.9-1.0, 0.9-0.92, 0.92-0.94, 0.94-0.96, 0.96-0.98, or 0.98-1.0.
In the airport roadbed settlement monitoring method based on distributed optical fiber burying, provided by the invention, the beta is related to the self property and the state of the optical fiber, and the value of the beta of the used optical fiber can be obtained through pre-experimental measurement. The standard deviation coefficient β is calculated by equation (3):
Figure BDA0002669256090000091
(3). In a specific embodiment of the present invention, two ends of an optical cable used in a monitoring system may be fixed in a laboratory in advance, the middle of the optical cable is suspended, known deformation is applied to the optical cable, a BOTDR distributed sensor connected to the optical fiber measures a strain amount of the optical fiber, and β that minimizes a calculated deformation error is selected as a β value of the optical fiber according to equation (3). Then, in the calculation of the concrete engineering monitoring, the beta value can be used. The value of the standard deviation coefficient beta can be usually 0.2-1.0, 0.2-0.4, 0.4-0.6, 0.6-0.8, or 0.8-1.0.
According to the airport roadbed settlement monitoring method based on distributed optical fiber embedding, the integral settlement distance of the airport roadbed can be obtained according to the sum of the relative settlement distance and the absolute settlement distance. The relative settlement distance, i.e. the relative settlement distance of a measurement point in the airport runway foundation relative to the airport runway foundation itself, can be based on the estimated displacement as described above
Figure BDA0002669256090000092
And calculating to obtain the settlement distance of the measuring point relative to the original pavement actually by adding the settlement distance of the airport pavement itself to the relative settlement distance of the obtained measuring point relative to the airport pavement itself. The settlement distance of the whole of each position of the airport pavement base can be obtained by measuring through a single-point settlement measuring instrument and a whole settlement measuring instrument. For example, the airport runway foundation itself for a particular measurement point can be obtained by a single-point settlement gaugeAnd the settlement distance of each part of the airport pavement base per se can be determined by obtaining the relative difference value of each part of the airport pavement base per se relative to the specific measuring point according to the integral settlement measuring instrument.
A third aspect of the present invention provides a computer readable storage medium having stored thereon a computer program which, when being executed by a processor, carries out the steps of the distributed optical fiber burying based airport roadbed settlement monitoring method as provided by the second aspect of the present invention.
A fourth aspect of the present invention provides an apparatus comprising: a processor and a memory, the memory being configured to store a computer program, the processor being configured to execute the computer program stored by the memory to cause the apparatus to perform the steps of the distributed optical fiber burying based airport roadbed settlement monitoring method provided by the second aspect of the present invention.
A fifth aspect of the invention provides an apparatus, which may comprise:
estimating actual strain
Figure BDA0002669256090000093
A calculation module for calculating and obtaining the estimated actual strain according to the formula (1)
Figure BDA0002669256090000094
Figure BDA0002669256090000095
Wherein the content of the first and second substances,
Figure BDA0002669256090000096
is the average strain;
(x) Is the difference value of the strain quantity of the metal-based cable-shaped optical cable (22) and the strain quantity of the temperature compensation optical cable (21), and x belongs to [0, l ];
alpha is a strain reduction coefficient and represents the relaxation degree of the optical fiber;
beta is a standard deviation coefficient and represents the redistribution of the internal strain of the optical fiber;
a maximum settlement position calculation module for determining the maximum settlement position according to equation (2), where x is the zero point of the function y (x)0Namely the maximum sedimentation position:
Figure BDA0002669256090000101
wherein the content of the first and second substances,
Figure BDA0002669256090000102
Figure BDA0002669256090000103
estimate displacement
Figure BDA0002669256090000104
A calculation module for calculating and obtaining the estimated displacement according to the formula (5)
Figure BDA0002669256090000105
Figure BDA0002669256090000106
Optionally, the system further comprises an overall settlement distance calculation module, configured to obtain an overall settlement distance of the airport runway foundation according to a sum of the relative settlement distance and the absolute settlement distance.
In the present invention, the operation principle of each module in the above apparatus may refer to the above-mentioned airport roadbed settlement monitoring method based on distributed optical fiber burying, which is not described herein again.
The distributed optical fiber in the prior art has wide application prospect in foundation settlement monitoring, but the distributed optical fiber is mainly directly buried at present and cannot meet the requirement of large-range monitoring of engineering.
The airport roadbed settlement monitoring structure and method based on distributed optical fiber burying are different from the traditional point type monitoring method, and the distributed optical fiber is used as a sensing medium and a transmission channel, so that remote, lossless, anti-interference, continuity and intelligent monitoring of roadbed settlement is realized. In addition, the invention provides an optical fiber strain-vertical displacement analysis and roadbed subsidence back calculation method based on a calibration test, and simultaneously provides a construction method for transverse embedding of a distributed optical fiber, so that the method can give early warning to roadbed differential subsidence which may damage the structural strength of a pavement and threaten the taking-off and landing safety of an airplane on the whole, and ensure the smoothness and durability of a runway and the operation safety of an airport.
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Example 1
The embodiment relies on the international airport intelligent runway project of Chengdu Tianfu, the settlement distribution condition of the roadbed soil is monitored by adopting a metal-based cable-shaped optical cable (Suzhou Nanzhi supply, model NZS-DTS-C08), the temperature change is compensated by adopting a high-strength steel wire armored optical cable (Suzhou Nanzhi supply, model NZS-DTS-C08), the monitoring and verification data are assisted by a high-precision intelligent settlement meter, the single-point settlement measuring instrument is supplied by Suzhou Nanzhi supply, model NZS-FBG-DS (1), the integral settlement measuring instrument is supplied by Suzhou Nanzhi intelligence supply, and model NZS-FBG-HD.
Firstly, a calibration test is started, and the correlation between the optical fiber strain and the vertical displacement position is analyzed through an FTB 2505 type distributed optical fiber demodulator: (1) fixing the deformation applying position and adjusting the deformation amount; (2) the deformation amount is fixed, and the deformation applying position is adjusted. Fig. 4(a) shows the strain of the optical fiber after different amounts of deformation are applied to the midpoint, and fig. 4(b) and (c) show the strain of the optical fiber after the same amount of deformation is applied to different positions on the left and right sides of the midpoint. The larger the total deformation length of the optical fiber is, the larger the analysis result is visuallyThe larger the strain of the optical fiber is, the more the engineering experience is met. Substituting test results (x) and calibration parameters
Figure BDA0002669256090000111
According to operator
Figure BDA0002669256090000112
The reverse sedimentation is shown in FIGS. 5(a) to (c), respectively. As can be seen from the figure, the relative error between the analysis value of the deformation amount and the optical fiber length is less than 0.5%, and the engineering feasibility and the applicability are good.
When the distributed optical fiber is buried in the field slot, the roadbed is filled to a specified elevation, the field is leveled and cleaned, and hard objects such as massive gravels, plant roots and the like are dug out. And paving a layer of fine sand with the thickness of about 5cm at the bottom of the groove, straightening and tightening the distributed optical fiber, sleeving a corrugated pipe for protection, backfilling the fine sand with the thickness of 40cm, backfilling original soil for removing broken stones on the fine sand, and detecting the access and analysis conditions of the optical fiber. The distribution length of the distributed optical fibers is determined according to actual needs, the distributed optical fibers can generally cover the whole airport runway range, the length of one distributed optical fiber is 2000-6000 m, and the specific length in the embodiment is 5000 m. The method is characterized in that calibration precision and engineering cost are considered, a single-point settlement measuring instrument or an integral settlement measuring instrument is generally arranged at intervals of 20-40 m, the laying scheme in the embodiment is that the single-point settlement measuring instrument or the integral settlement measuring instrument is arranged at intervals of 15m, the distance between the single-point settlement measuring instrument or the integral settlement measuring instrument and a distributed optical fiber of a corresponding point position is not more than 30cm, the distance between a temperature compensation optical cable and a metal-based cable-shaped optical cable is not more than 5cm, and the end parts of the temperature compensation optical cable and the metal-based cable-shaped optical.
The strain data of the high-strength steel wire armored optical cable 21 at the same position is subtracted from the strain data of the metal-based cable-shaped optical cable 22, and the roadbed settlement monitoring data after temperature compensation is obtained as shown in fig. 6. According to the strain conditions of the distributed optical fibers at each monitoring point shown by the monitoring data, by utilizing the airport roadbed settlement monitoring method based on distributed optical fiber burying, the vertical deformation (namely settlement) of the soil foundations at the monitoring points can be obtained through the transverse strain calculation of the distributed optical fibers, and the obtained roadbed soil body settlement distribution condition is the relative settlement between the monitoring points of the distributed optical fibers, as shown by the black line in fig. 7, the interval of the measuring points on the black line is 0.04 m. According to the measurement data of the high-precision integral settlement measuring instrument 23 and the single-point settlement measuring instrument 24, as shown by blue dots in fig. 7, the absolute settlement is 29.2312mm, 23.0720mm, 16.6855mm and 10.4307mm from left to right, respectively, and the monitoring data of the distributed optical fiber at the corresponding position is calibrated; and then, according to the relative settlement between the monitoring point positions of the distributed optical fiber, the real settlement conditions of all the roadbed soil bodies in the coverage area of the distributed optical fiber can be obtained, as shown by red lines in fig. 7, and the differential settlement between different areas of the runway is calculated. Taking the monitoring data of 2018.10.26 in fig. 6 as an example, the relative settlement calculated from the distributed fiber strain data and the true settlement corrected with the single point/global settlement gauge data are shown in fig. 7.
In conclusion, the present invention effectively overcomes various disadvantages of the prior art and has high industrial utilization value.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims (10)

1. An airport roadbed settlement monitoring structure based on distributed optical fiber embedding is characterized by comprising an airport pavement (1), the airport pavement (1) comprises a pavement layer (11) and a pavement base layer (12), an airport roadbed settlement monitoring system (2) is arranged in the road base layer (12), the airport roadbed settlement monitoring system (2) comprises a temperature compensation optical cable (21), a metal-based cable-shaped optical cable (22), an integral settlement measuring instrument (23) and a single-point settlement measuring instrument (24), the extending directions of the temperature compensation optical cable (21), the metal matrix cable-shaped optical cable (22) and the integral settlement measuring instrument (23) are consistent, the single-point settlement measuring instrument (24) is positioned in the extending direction of the integral settlement measuring instrument (23), the metal-based strand-shaped optical cable (22) extends linearly, and the temperature compensation optical cable (21) extends non-linearly.
2. The distributed fiber optic burying-based airport roadbed settlement monitoring structure as claimed in claim 1, wherein said roadbed layer (12) is provided with a plurality of airport roadbed settlement monitoring systems (2);
and/or the temperature compensation optical cable (21), the metal-based cable-shaped optical cable (22) and the integral settlement measuring instrument (23) are transversely buried according to the extension direction of the airport runway;
and/or the airport ballast settlement monitoring system (2) comprises a plurality of single-point settlement measuring instruments (24), and the single-point settlement measuring instruments (24) are uniformly distributed in the extending direction of the integral settlement measuring instrument (23).
3. The distributed optical fiber burying-based airport pavement settlement monitoring structure of claim 1, wherein the length of said temperature compensation optical cable (21) per unit width of the airport pavement (1) is 1.05 to 1.20 times the length of the metal-based cable (22).
4. The distributed fiber optic burying-based airport roadbed settlement monitoring structure of claim 1, wherein the temperature compensation optical cable (21) comprises a first fiber body and a first cable jacket for wrapping the first fiber body;
and/or, the metal matrix cable (22) comprises a second optical fiber body and a second cable jacket for wrapping the second optical fiber body;
and/or the temperature compensation optical cable (21), the metal-based cable-like optical cable (22), the integral settlement measuring instrument (23) and the single-point settlement measuring instrument (24) are buried in fine sand;
and/or the temperature compensation optical cable (21), the metal-based cable-shaped optical cable (22), the integral settlement measuring instrument (23) and the single-point settlement measuring instrument (24) are covered with backfilled undisturbed soil;
and/or the backfilled undisturbed soil is doped with bentonite.
5. The distributed fiber optic burying-based airport roadbed settlement monitoring structure of claim 1, further comprising BOTDR distributed sensors, said BOTDR distributed sensors being respectively connected to optical fibers in the optical cable.
6. A method for monitoring the settlement of an airport roadbed based on distributed optical fiber embedding, which monitors the settlement of the airport roadbed by using the airport roadbed settlement monitoring structure based on distributed optical fiber embedding according to any one of claims 1 to 5, and comprises the following steps:
obtaining the estimated actual strain by calculation according to the formula (1)
Figure FDA0002669256080000011
Figure FDA0002669256080000021
Wherein the content of the first and second substances,
Figure FDA0002669256080000022
is the average strain;
(x) Is the difference value of the strain quantity of the metal-based cable-shaped optical cable (22) and the strain quantity of the temperature compensation optical cable (21), and x belongs to [0, l ];
alpha is a strain reduction coefficient and represents the relaxation degree of the optical fiber;
beta is a standard deviation coefficient and represents the redistribution of the internal strain of the optical fiber;
determining the maximum sedimentation position according to equation (2), where the zero point x of the function y (x) is x0Namely the maximum sedimentation position:
Figure FDA0002669256080000023
wherein the content of the first and second substances,
Figure FDA0002669256080000024
Figure FDA0002669256080000025
obtaining the estimated displacement by calculation according to the formula (5)
Figure FDA0002669256080000026
Figure FDA0002669256080000027
Thereby obtaining the relative settlement distance of the airport pavement base.
7. The method for monitoring airport roadbed subsidence based on distributed optical fiber burying as claimed in claim 6, wherein the strain reduction coefficient α is total optical fiber elongation Δ lThe ratio of the strain reduction coefficient alpha to the actual total elongation delta l of the optical fiber is 0.9-1.0;
and/or the standard deviation coefficient beta is 0.2-1.0;
and/or the standard deviation coefficient beta is obtained by calculating the formula (3):
Figure FDA0002669256080000028
and/or obtaining the integral settlement distance of the airport pavement according to the sum of the relative settlement distance and the absolute settlement distance, wherein the absolute settlement distance is obtained by measuring through an integral settlement measuring instrument (23) and a single-point settlement measuring instrument (24).
8. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the method for monitoring the settlement of an airport foundation based on distributed optical fiber burying according to any one of claims 6 to 7.
9. An apparatus, comprising: a processor and a memory, the memory storing a computer program, the processor being configured to execute the computer program stored by the memory to cause the apparatus to perform the steps of the distributed fiber optic burying based airport roadbed settlement monitoring method as claimed in any one of claims 6 to 7.
10. An apparatus, the apparatus may comprise:
estimating actual strain
Figure FDA0002669256080000029
A calculation module for calculating and obtaining the estimated actual strain according to the formula (1)
Figure FDA00026692560800000210
Figure FDA0002669256080000031
Wherein the content of the first and second substances,
Figure FDA0002669256080000032
is the average strain;
(x) Is the difference value of the strain quantity of the metal-based cable-shaped optical cable (22) and the strain quantity of the temperature compensation optical cable (21), and x belongs to [0, l ];
alpha is a strain reduction coefficient and represents the relaxation degree of the optical fiber;
beta is a standard deviation coefficient and represents the redistribution of the internal strain of the optical fiber;
a maximum settlement position calculation module for determining the maximum settlement position according to equation (2), where x is the zero point of the function y (x)0Namely the maximum sedimentation position:
Figure FDA0002669256080000033
wherein the content of the first and second substances,
Figure FDA0002669256080000034
Figure FDA0002669256080000035
estimate displacement
Figure FDA0002669256080000036
A calculation module for calculating and obtaining the estimated displacement according to the formula (5)
Figure FDA0002669256080000037
Figure FDA0002669256080000038
Optionally, the system further comprises an overall settlement distance calculation module, configured to obtain an overall settlement distance of the airport runway foundation according to a sum of the relative settlement distance and the absolute settlement distance.
CN202010928321.3A 2020-09-07 2020-09-07 Airport roadbed settlement monitoring structure and method based on distributed optical fiber embedding Pending CN112066945A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112797951A (en) * 2021-01-26 2021-05-14 同济大学 Load-bearing type airport roadbed settlement monitoring structure and method based on BOTDR technology
CN113251996A (en) * 2020-12-21 2021-08-13 同济大学 Intelligent runway
WO2022127142A1 (en) * 2020-12-17 2022-06-23 同济大学 Intelligent runway and runway surface information monitoring method
US20220228853A1 (en) * 2021-01-15 2022-07-21 Sun Yat-Sen University Detection apparatus and method for flow deformation of foundation layer in horizontal direction

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2022127142A1 (en) * 2020-12-17 2022-06-23 同济大学 Intelligent runway and runway surface information monitoring method
CN113251996A (en) * 2020-12-21 2021-08-13 同济大学 Intelligent runway
CN113251996B (en) * 2020-12-21 2022-07-26 同济大学 Intelligent runway
US20220228853A1 (en) * 2021-01-15 2022-07-21 Sun Yat-Sen University Detection apparatus and method for flow deformation of foundation layer in horizontal direction
US11549804B2 (en) * 2021-01-15 2023-01-10 Sun Yat-Sen University Detection apparatus and method for flow deformation of foundation layer in horizontal direction
CN112797951A (en) * 2021-01-26 2021-05-14 同济大学 Load-bearing type airport roadbed settlement monitoring structure and method based on BOTDR technology

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