CN105890537B - The technical solution and system of the distributing optical fiber sensing of induced joint deformation monitoring - Google Patents
The technical solution and system of the distributing optical fiber sensing of induced joint deformation monitoring Download PDFInfo
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- CN105890537B CN105890537B CN201610505697.7A CN201610505697A CN105890537B CN 105890537 B CN105890537 B CN 105890537B CN 201610505697 A CN201610505697 A CN 201610505697A CN 105890537 B CN105890537 B CN 105890537B
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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
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- 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
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Abstract
The Distributed Optical Fiber Sensing Techniques scheme and system of a kind of induced joint deformation monitoring are disclosed, it is related to the crossing domain of dam safety monitoring technology and optical fiber sensing technology, the defect and distributing optical fiber sensing to overcome the conventional means of induced joint deformation monitoring are used for the blank of dome dam deformation monitoring.The characteristics of for dome dam and difficult point provide two kinds of unique curved optical fiber encapsulating structures: the fiber-optic monitoring plate of weak curved beam and micro-bend beam type.Based on error analysis and curved beam control height-camber beam segmentation configuration, it is ensured that the excellent properties of fibre strain monitoring, highly reliable-long-life, convenient and practical.The convenient practical laying mounting means in the gallery of arch dam and the dam foundation, vertical shaft and footrill is provided, to realize the various dimensions-online telemetering that space-time extensively covers on a large scale of 3 component of arch dam-dam foundation dam abutment internal modification (radial-tangential horizontal displacement, vertical displacement).Optical Demodulation instrument can a tractor serves several purposes, can and survey silt position-reservoir sedimentation etc. before concrete temperature-library water temperature-dam.
Description
Distributed Fiber Optic Sensing Technology and System for Monitoring
of Deformation of High Arch Dam
Technical field
The invention belongs to the crossing domain of dam safety monitoring technology and optical fiber sensing technology, in particular to a kind of induced joint
The technical solution and system of the distributed optical fiber sensing monitoring of deformation inside the dam body and the dam abutment dam foundation of dome dam, it can be achieved that become
The on-line monitoring that various dimensions-space-time of the distributing optical fiber sensing of shape extensively covers.
Background technique
The conventional method of arch dam horizontal displacement monitoring is located in typical section in dam body based on normal line method, single hop line
It is about 50m；Vertical displacement monitors multi-purpose static level.Dam foundation dam abutment deformation monitors multi-purpose reversed pendulum, tension wire, inclinometer, more
Point displacement meter, indium steel wire displacement meter etc..Wherein, most widely used vertical frontal line can only survey horizontal displacement, have a single function, the construction time
It is difficult to form observation system；Most equipment need to be observed using the electric logging equipments such as coordinatograph, durability, long-time stability and
Time between failures are all barely satisfactory, and correction, replacement, maintenance load are big；It is usually placed in typical section, cannot be considered in terms of complete
Dam, information content is few, and there are localities and limitation；Equipment component needs artificial execute-in-place, such as movable inclinometer, it is difficult to real
Present line telemetering.For these problems with the increase of height of dam, challenge is further prominent.
Induced joint often uses hyperbolic dam type, Ru Ertan, voe, silk screen, the dam small stream Luo Du etc..For the monitoring of arch dam internal modification
Speech, hyperbolic dam type is both feature, even more difficult point." hyperbolic " limits the application of the means such as tension wire, laser alignment.In this regard, industry
The recent innovation effort in boundary is the case that the dams such as Bai Shan, voe use fold-line-shaped vacuum laser 3 d deformation monitoring ,-according to document
[1]-" but its measurement accuracy is also undesirable, not can solve versatility monitoring problem "[1]。
So far, Distributed Optical Fiber Sensing Techniques and system there is no the example and technical solution for arch dam deformation monitoring, only
Have distributing optical fiber sensing/quasi-distributed optical fiber sensing FBG (fiber bragg grating) for underground engineering, stake work, ground
The example of engineering, pipeline, the model experiment of concrete dam etc. deformation detection.
Cairo, EGY subway 3# line passes through soft soil layer, and when excavation uses BOTDA (Brillouin optical time domain analysis) type light
Fine deformation monitoring pipe carries out soil layer settlement observation.Sighting tube is using smooth surface circle plastic tube Long 12~20m, pipe
3 sensor fibres are laid in outer surface, by Euler-Bernoulli Jacob's elasticity beam theory, show that sedimentation of the soil layer along test tube longitudinal direction is distributed, effect
Fruit is good[2]。
In Shanghai Underground route, the encapsulating structure of optical fiber is using commonInclinometer pipe, long 84m.Tube top tube bottom is each
A groove is opened, is glued into FBG.The optical fiber measured value of sedimentation is consistent substantially with comparison measured value[3]。
In Hong Kong New Territories landslide, long 15m'sIn 4 symmetrical grooves of inclinometer pipe, 10 FBG are respectively installed, are usedDrilling embedment stratum, cement mortar build-in.480 days observation data of its horizontal distortion, with conventional inclinometer pipe result
Substantially it is consistent[4]。
One deep basal pit of Nanjing, sensor fibre is pasted onto the groove of symmetrical two sides of pvc pipe, and one side is towards foundation pit
Wall cheats other soil layer, deep 32m with the vertical embedment of drilling.The pipe amount of deflection is measured using BOTDR (Brillouin light Time Domain Reflectometry) in excavation
Deformation, i.e. earth horizontal displacement, meet well with total station measured value[5]。
Shanxi spoil power plant is to diameter 800mm, long 31m, 35m bored concrete pile, using Brillouin's type sensor fibre, quiet
It carries and detects pile body amount of deflection, strain in test.2 curb pile body two sides of sensor fibre are arranged symmetrically, and obtain full and accurate achievement.
Nearby gas pipeline is about 500m to Italian Rimini, using BOTDA brillouin distributed optical fiber sensing monitoring steel
Pipe detects energy using the measurement stability, long-term reliability and the distributed remote that show the technology along the strain and deformation of journey
Power[6]。
In the concrete gravity dam model test of Sichuan Wudu, by FBG strain gauge, the X-Y on plastics round bar surface is bonded in symmetrical
On line, FBG sensor bar is constituted,The long 50cm of bar.A bar is respectively buried in dam body-dam foundation, by Euler's elasticity beam theory,
By the vertically and horizontally horizontal displacement of round bar bending deflection detection model, mutually verified with displacement meter, measured value meets well[7]。
As it can be seen that distributed optical fiber sensing monitoring deforms, at home and abroad tentatively answered in some close engineering fields
With, it is shown that effective practicability.The industry common recognition in the field is: the core and difficult point of distribution type fiber-optic deformation sensing are light
Interface (Interface) between fine and measured structure[8].The encapsulating structure of elongated beam type is generallyd use as described above as boundary
Face.Packaging part especially plays the work of sensing element (pre-converter) while its optical fiber packaging protection gets up, exempts damage
With the deformation of tested engineering, the strain of encapsulation beam body being converted into, so as to optical fiber perception.I.e. optical fiber is sealed with elongated straight-bar/straight tube
Dress measures the distribution of tension and compression side strain, determines its deflection deformation and linear deformation by Euler's beam theory.
When the fibre strain monitoring technology existing engineer application, when being transplanted to arch dam engineering, critical issue is: straight line
The optical fiber encapsulating structure (straight beam) of shape, it is difficult to adapt to hyperbolic dam shape；It must propose the practical curved shape envelope suitable for dome dam
Shape, construction and the new technical solution of precision analysis of assembling structure；Xiang Ying Solution is also wanted to determine optical fiber sensing system in height arch
Layout Problem in dam；And optimize the (FBG) demodulator type selecting of fibre strain monitoring system.
The technical problem to be solved by the present invention is to overcome the defect and distribution of the conventional equipment of induced joint deformation monitoring
Fibre Optical Sensor be used for dome dam deformation monitoring blank, provide it is a kind of adapt to dome dam particular demands, have engineering
The induced joint of practicability deforms the technical solution and system of online telemetering.
Main literature: [1] Huang Huibao, Jiang Hua is expensive, Zhang Zebin, and great writer's vacuum laser Huaihe River is directly in the big position of Pubugou Hydropower Station
Third rock-fill dams international symposium collection of thesis, on October 25th, 2013, Chinese Kunming, pp:891- are applied in the monitoring of shifting amount
895.[2]V.Dewynter et al.Brillouin optical fiber distributed sensor for
settlement monitoring while tunneling the metro line 3 in Cairo,Egypt,Proc.of
SPIE [J], Vol.7503,75035M. [3] F.Wang et al.Monitoring shield tunnel settlement
using FBG-PVC sensor method[C],Proc.of 3rd Int.Forum on Opto-electronic
Sensor-based Monitoringin Geo-engineering,Sept.29-30,2010,Suzhou China.[4]
H.H.Zhu et al.An optical fibre monitoring system for evaluating the
performance of a soil nailed slope,Proc.of 4th Int.Forum on Opto-electronic
The such as Sensor-based Monitoringin Geo-engineering, Oct.11-13,2012. [5] Liu Jie, Shi Bin are based on
Foundation pit deformation distributed monitoring experimental study [J] rock-soil mechanics of BOTDR, 2006,27 (7) [6] D.Inaudi.Field
Application of strain and temperature fiber optic sensors [C], Proc.of 2nd
Int.Forum on Opto-electronic Sensor-based Monitoring in Geo-engineering,
Oct.18-19,2007,Nanjing,China.[7]H.H.Zhu et al.Fiber optic displacement
monitoring in laboratory physical model testing.Proc.3th Int.Forum on Opto-
Electronic Sensor-based Monitoring in Geo-engineering [C], Sept.29-30,2010,
Suzhou China.[8]X.Bao et al.Distributed Fiber-optic Sensors Based on Light
Scattering in Optical Fibers[M].Handbook of Optical Sensors(Ed.Jose Luis
Santos), CRC Press, London New York, 2015.
Summary of the invention
(1) the principles of science based on technical solution
This patent belongs to hydraulic engineering and the large span mixing together as two technical fields of high-tech Fibre Optical Sensor,
Its principles of science includes two spheres of learning: optical fiber optics and Elasticity.
(1) optical fiber optical theory
According to the latest developments of optical fiber optical field, two kinds of intrinsic scatterings of fiber optical waveguide --- Brillouin scattering, Rayleigh dissipate
It penetrates, it is all sensitive with two kinds of mechanical quantities of temperature to straining[9~11].Respectively distinctive optical parameter becomes strain and temperature for two intrinsic scatterings
The information carrier of degree is as follows:
1) Brillouin (Brillouin) scatters light -- the frequency displacement of brillouin gain spectrum peak and temperature and strain increment line
Property related, basic relational expression are as follows:
Δvb=C11Δε+C12ΔT (1)
In formula, Δ vbFor brillouin gain spectrum frequency displacement, Δ ε is strain increment, and Δ T is temperature increment, C11It is answered for Brillouin
Change-coefficient of frequency, C12For Brillouin's temperature-frequency coefficient.Fibre strain and temperature can be measured by measuring Brillouin shift,
Optical fiber can be obtained along the Temperature Distribution of journey through decoupling.Novel prepulsing (Pulse-Pre-Pump) Brillouin optical time domain analysis instrument
PPP-BOTDA, pulse minimum widith reach 0.2ns, and space divides variability up to 2~10cm, 7.5 ε/0.35 DEG C μ of measurement accuracy.
2) Rayleigh (Rayleigh) scatters light -- caused by the residual strain that fiber core generates in pulling process
Rayleigh beacon light, frequency displacement and temperature and strain increment are linearly related, and basic relational expression is
ΔvR=C21Δε+C22ΔT (2)
In formula, Δ vRFor Rayleigh scattering optical frequency shift, C21For Rayleigh strain-coefficient of frequency, C22For Rayleigh temperature-frequency system
Number.Recent commercialization-the TW- already of Brillouin-Rayleigh synthesis system (Hybrid Brillioun-Rayleigh system)
COTDR (harmony wavelength Coherent optical time domain reflectometer), working performance is suitable with above-mentioned PPP-BOTDA, and can realize temperature-strain
Automatic decoupling.These are the signal-to-noise ratio of raising system, the reliability of enhancing observation data provides urgently advantage.
(2) theory of mechanics
1) straight beam -- in elastic theory, for Euler-Bernoulli Jacob's three dimensional elasticity beam theory model of cross-section straight beam
Basic assumption are as follows: beam body is homogeneous linear elastic materials；Amount of deflection is relative to span category small deformation；Section remains flat after deformation
Face；It is shear-deformable to ignore；The additional bending moment of axial force is ignored；Beam body is not by torque.The tension and compression side strain of beam is distributed
It is corresponded with its deflection deformation, the multiple integral through straining can acquire amount of deflection；To the multiple integral of strain mean, beam is obtained
Linear deformation.
2) the circumference stress σ of bend sheet-beam -- the pure bending of planar arc curved beamθExpression formula is[12]
In formula, a is curved beam inside radius, and b is curved beam outer radius, and r is polar coordinates radius vector, and θ is argument, and M is torque,
Obviously, log series model is presented along depth of section in tangential stress, hence it is evident that deviates the line of the section stress in the case of straight beam
Property distribution, there are non-linear effects and error.
3) plane camber beam -- the Common examples of plane camber beam, such as the camber beam used in the curved bridge of highway；In arch dam monitoring,
The monitoring board (attached drawing 2 its (13)) of setting in gallery just belongs to this kind of structural shape.Its mechanics feature is: beam body is born
Vertical load while generating vertical bending moment, be also associated with lateral torque.This bending-twisted coupling, leads to beam body
Stress-deformation distortion, causes non-linear, and torque can generate additional amount of deflection[13]。
Main literature: the Beijing Fundamentals of Fibre Optical Sensors [M] such as [9] Fang Zujie: Science Press, 2012；[10]
K.Kishida et al.Study of optical fiber strain-temperature sensitivities using
hybrid Brillouin-Rayleigh system,Photonic Sensors,DOI:10.1007/s 13320-013-
0136-1；[11]Sylvie Delepine-Lesille et al.Validation of CW-COTDR method for
25km distributed optical fiber sensing,Proc.of SPIE Vol.8794 8743-1；[12] Cheng Chang
An ancient unit of weight, the Beijing the such as Wang Ying heavily fortified point Elasticity [M]: Higher Education Publishing House, 1999；[13] He Shuanhai, bridge structure theory and meter
The Beijing calculation method [M]: People's Transportation Press, 2003.
(2) technical solution
(1) citation form of sensor fibre encapsulating structure is deformed
The shape of encapsulating structure and construction it is light and practical, the success or failure for the engineer application of fibre strain monitoring have
Decisive role.The optical fiber encapsulating structure of aforementioned existing deformation monitoring is round cut in respect of two kinds of round tube, round bar forms
Face.Induced joint project scale is big, rigidity is big.If the encapsulation of optical fiber uses this circular cross-section beam, to provide necessary sensing
Sensitivity, diameter about 1~2m (the main boundary strain value by camber beam body is directly proportional to deck-molding), occupied space is big, it is difficult to utilize
Conventional gallery, is arranged installation.
For this purpose, being directed to the application of dome dam, this patent follows the structure of dimensionality reduction (Dimension reduction)
Think, a kind of book template encapsulating structure-the narrow rectanglar girder of sensor fibre, i.e. fiber-optic monitoring plate ellbeam, such as Fig. 1 are provided, wherein
1 is sensor fibre, and 2 be transmission cable, and 3 be optical signal demodulation instrument, and 4 be package board, and 5 be the fixed end of package board, and 6 be micro-pipe.?
Package board long side two sides respectively set 1 micro-pipe (diameter about 15mm), and to lay sensor fibre group, (routing of two sides micro-pipe inner fiber is
U-shaped (U-shaped thin portion is being not shown in the figure)), as tension and compression side of the plate shape Euler beam body in bending, fibre strain prison can be formed
Drafting board ellbeam, referred to as fiber-optic monitoring plate or monitoring board.Fiber-optic monitoring plate shape depth of beam is about 0.5~2m.In every micro-pipe
The composition of sensor fibre group be, when optical signal demodulation instrument selects BOTDA type, to add 2 using 3~4 fixed sm fibers
Loose tube fiber (is used for temperature-compensating)；It is when optical signal demodulation instrument selects Brillouin-Rayleigh synthesis system, then tight using 3~5
Cover sm fiber.
Sensor fibre in each micro-pipe can measure strain (and temperature) continuous function of the one-dimensional space along journey.Work as monitoring
Plate arrange vertically and its end it is fixed when, become the cantilever spring beam of two dimension of narrow and long rectangular section, 2 deformations can be observed simultaneously
Component: the amount of deflection and its linear deformation of plate ellbeam.When monitoring board it is horizontally disposed-end it is fixed when, amount of deflection appears in horizontal plane
It is interior.It is clear to, along a survey line by the orthogonal laying of two monitoring boards, then 3 component of deformation (the i.e. vertical position along considerable drafting board ellbeam
It moves, radial level displacement, tangential horizontal displacement).
(2) the linearisation configuration of package board ellbeam and its technical solution of analysis are bent
Feasibility-practicability key of Curved package board ellbeam scheme, is its linearity.Linear transducer is reason
The sensor thought, and bend sheet-beam and camber beam all exist it is non-linear on mechanics.The non-linear error for not only increasing sensor, and
And observation data analysis is made to complicate, is time-consuming bothersome.To solve this key problem, corresponding quantitative analysis and error are now provided
Estimation, and then propose that it linearizes the technical solution of (Linearization) configuration.So-called linearisation configuration is exactly building essence
Skilful microbend packaging part had not only adapted to the mounting location of hyperbolic dam type but also can eliminate the influence of nonlinearity erron, and had been allowed to be converted to
For linear transducer, and it is able to maintain enough accuracy.
1) straight beam: the non-linear factor of straight beam is usually predominantly the shearing in shear bending, lures beam section warpage into.With equal
As typical case, the analytic solutions expression formula that straight beam direct stress σ is distributed is cloth load rectangular section simply supported beam[12]
In formula, b is deck-siding, and h is deck-molding, and L is span, and (x-y coordinate origin is in beam axis for stress point to natural axis distance by y
The span centre point of line), q is evenly load intensity；σMFor the direct stress that moment of flexure generates, i.e. previous item in formula (4), σQIt is produced for shearing
Latter in raw direct stress, i.e. formula (4).According to formula (4), it is not difficult to export the σ of spaning middle sectionQWith σMThe ratio between ζ be
The nonlinearity erron that the shearing factor of the freely-supported spring beam of different span-depth radios generates, such as table 1.
Table 1
The result shows that: as long as packaging part is elongated enough, span-depth radio >=5~10, shear the nonlinearity erron very little of generation, beam
Section stress keeps linear distribution, i.e., elongated straight beam is linear splendid as sensibility elasticity element.
2) bend sheet-beam: the mechanical characteristics that curved beam is different from straight beam are, Euler-Bernoulli Jacob's cutting plane assume it is general not at
It is vertical[12], i.e., in the stress linear distribution of straight beam, non-linear (logarithm) distribution is then changed into curved beam, such as formula (3), concave edge is answered
Power deformity is strengthened, and absolute value is more than flange stress value.In consideration of it, being quantitative analysis meter, with the ratio between concave-convex edge stress, characterization
The non-linearization degree of curved beam stress distribution.
If concave edge fiber stress isChimb fiber stress isThe ratio of the two absolute value is?
The linear distribution situation of straight beam, it is clear that have: a=b, and ξ=1.Nonlinearity erron δ caused by the log series model state of section stress
It is represented by
δ=ξ -1 (6)
In curved beam, if b=λ a, it is apparent from λ=1+h/a, i.e. λ contains the opposite deck-molding in inside radius a of deck-molding h ratio.
According to formula (3), through being derived from
The Non-Linear Error Analysis of the opposite deck-molding of the difference of bend sheet-beam is as a result, such as table 2.
Table 2
The result shows that: as long as the deck-molding of curve monitoring board ellbeam is controlled within the 2~3% of inner radius values, then it is bent
Nonlinearity erron caused by beam shape meets requirement of engineering precision less than 1%~3%, that is, nonlinearity erron is negligible,
And directly adopt Euler's straight beam mechanical model and deflection deformation algorithm.
3) plane camber beam: research achievement shows when central angle≤30~50 ° of plane camber beam, and it is additional can to omit torsion
Amount of deflection is reduced to straight beam buckling problem and accurate enough[13], the engineering practice of a large amount of curved bridge of highway also demonstrates this
Point.
In summary error analysis result and related achievement provide curved beam control height-camber beam segmentation make, such as scheme
Shown in 2,7 be arch ring in figure, and 8 be gallery, and 9 be dam abutment footrill, and 10 be gallery upstream wall, and 11 be roof arch of gallery, and 12 be horizontal prison
Drafting board, 13 be vertical monitoring board, and 14 be monitoring board fixed end.Fig. 2 a is gallery cross section, and Fig. 2 b is the A-A section of Fig. 2 a, display
The upper viewing view of the curved beam type monitoring board 12 laid at roof arch of gallery；Fig. 2 c is the B-B section of Fig. 2 a, and gallery is close in display
The upper viewing view of the camber beam-type monitoring board 13 of upstream wall laying.To be configured to the weak curved linearisation of following two
Spring beam sensing element:
A) weak curved beam (Weakly curved beam)-the radius of curvature of induced joint often select by about 100~500m, deck-molding
0.5~2.5m (this deck-molding is also convenient for the installation of the arrangement in gallery, footrill, vertical shaft), so that it may control deck-molding in curved beam
Within the 1~2% of radius (λ≤1~2%), nonlinearity erron only about 1% is not significant, to become Europe on mechanical mode
Pull-up straight beam.
B) the center of maximum angle of micro-bend beam-the induced joint that China builds up and designs mostly is less than 100 °[9].For this purpose, right
In the camber beam packaging part of the big arch ring of central angle, broken across the camber beam of full arch circle in arch centerline using the configuration of segmentation
It opens, forms the single fixed end cantilever camber beam in left and right two, respective central angle is only half central angle of arch ring, can satisfy linear camber beam
Mechanical condition (central angle≤30~50 °), can be ignored torque non-linear effects[13], also become Euler on mechanical mode
Type straight beam.
Monitoring board ellbeam in vertical shaft is similar with this, the weak curved beam also comprising linearisation-and suitable river is to monitoring board (in Fig. 4 b
Its (18)) and linearisation micro-bend beam-Yokogawa is to monitoring board (it in Fig. 4 b (19)).The beam of arch dam to central angle generally all compared with
Small, the micro-bend beam in vertical shaft readily satisfies the condition of central angle≤30~50 °.
(3) technical solution of the arrangement of induced joint fibre strain monitoring
1) arrangement of gallery fiber-optic monitoring plate
It is set up in induced joint dam body and is equipped with multilayer Vertical Curve shape gallery, preferably as the primary cloth of full dam fiber-optic monitoring plate
Set occasion.Monitoring board is arranged in longitudinal gallery of different elevations, to monitor full arch dam in the horizontal displacement of each corresponding elevation
And vertical displacement.Concrete position are as follows: (1) vertically monitor it is smooth in gallery upstream wall (it in Fig. 4 (a) (10)), by its top edge
Journey is fixed on concrete wall vertical displacement and tangential horizontal position to dam body along monitoring (as used expansion bolt (or built-in fitting))
It moves；(2) level monitoring plate is laid in gallery dome portions, and by its upstream, lateral edge journey is fixed, to observe the dam body diameter of the respectively elevation
To, transverse horizontal displacement.The end of both monitoring boards is goed deep at mother rock of dam shoulder certain depth by the footrill of suitable length,
And it is made into fixed end, the datum mark (it in Fig. 2 (14)) as monitoring board.
2) arrangement of vertical shaft fiber-optic monitoring plate
In the vertical shaft of the close Shang You Ba Mian of typical section, the monitoring board of orthogonal is vertically arranged, such as Fig. 4 (b).
The drilling of its bottom surface is excavated, and is extended downwardly, is goed deep at basement rock appropriate depth, bottom is made into fixed end datum mark.With routine monitoring
The multiple segmentation of vertical line is different, and herein, vertical shaft and monitoring board are along smoothed curve, from basement rock deep datum mark,
It is extended continuously upwards, until dam crest.Radial monitoring board is along the upstream side borehole wall that journey is fixed on vertical shaft；Tangential monitoring board is in arch crown
In left monolith, its left side to be fixed on the borehole wall；In arch crown in right monolith, then its right side to be fixed on the borehole wall,
It is intended to be formed Euler's spring beam Ding Mian loading environment.While monitoring dam body horizontal displacement, amount of deflection and vertical displacement, may be used also
It observes dam foundation sedimentation, should be distributed and its change in time and space along journey dam body upstream surface concrete is vertical.
3) the internal modification monitoring of dam abutment Dam Foundation Rock
To monitor plate arrangement similar to corridor in dam using two sides irrigation gallery first, can excavate when necessary rock cave (or
Drilling), lay unidirectional or orthogonal monitoring board.While monitoring rock mass Three-direction deformation, can also monitor pass through it is each
The deformation and the changing of the relative positions of Gou Zao Mian, structural belt.
4) technical solution of fibre strain monitoring system composition
Fibre strain monitors the composition of system, sees attached drawing 3, specifically includes that sensor fibre 1- transmission cable 2- optical signal solution
It adjusts instrument 3 (main control computer, UPS etc. accessory are not shown).
Wherein, the preferably novel PPP-BOTDA (prepulsing Brillouin light time domain demodulation instrument) of optical signal demodulation instrument, pulse
Minimum widith reaches 0.2ns, and space divides variability up to 2~10cm, strains 7.5 μ ε of precision, strains 5 μ ε of repeatability, temperature accuracy reaches
0.35 DEG C, time of measuring 5s, distance range 50m~10km, it is applicable in sm fiber.Brillouin-Rayleigh synthesis system solution solution instrument TW-
COTDR also reaches similar performance, and two parameter of strain-temperature can be decoupled voluntarily.
For the performance for verifying PPP-BOTDA type optical fiber sensing system under the conditions of engineering site, used in Xi'an within 2011
PHC live static loading experiments and strain actual measurement, have carried out domestic technical identification for the first time, using well-known Switzerland's slide attack
It is checked.PHC diameter 500mm, the long 30m of stake are embedded to two-way strain sensing optical fiber in pile body, and embedment sliding is surveyed together
Micro- meter, 693~1464kN of test pile static load.As a result the strain measured value of two kinds of means is consistent substantially, and [the macro .PPP-BOTDA in river is distributed
Optical fiber sensing technology and its in test pile apply [J] rock-soil mechanics, 2011,32 (10): 3190-3195].
(4) beneficial effect of technical solution
1) principle/different properties multiple systems of the conventional equipment of arch dam internal modification monitoring, it is single for being simplified
Optical fiber sensing system；Monitoring system altitude is simplified, extremely refines, and eliminates movable member, significantly economization maintenance load,
It significantly improves the signal-to-noise ratio of system, guarantee the stability reliably and with long-term of observation data conscientiously, make with practical value
Advanced and applicable high-tech means.It at the initial stage of fiber optic sensing applications, complements each other with routine monitoring means, mutually confirms, when
The validity and scientific and technological level of dam safety monitor system can be significantly improved, it is expected to the height as induced joint safety monitoring field
One of technological means.
2) live artificial measuring point, manual operations are eliminated, real-time online telemetering is easy to implement.
3) monitoring of high dam internal modification is promoted and arrives networking/integrated horizontal, conducive to realize full dam deformation observation when
Empty all standing (normal line method in conventional equipment can only be arranged in a small number of monoliths, it is difficult to take into account comprehensively).In monitoring time overall process
On, optical fiber sensing system buries i.e. survey (monitoring board especially in gallery-grotto), and construction time data will not lack, and establishes symbol
Close actual displacement initial fields；Monitoring during construction system can fast access later period automated system, will not data outage.
4) optical fiber sensing system it is corrosion-resistant, it is anti-lightning strike, without electromagnetic interference, without abrasion, float almost without zero, steady operation is tens of
Year, maintenance load is minimum；Long-life-is highly reliable.The price reduction of optical fiber sensing system associated materials equipment is fast, performance improves fast, hair
It is big to open up potentiality.
5) optical signal demodulation instrument has the function of distributed temperature sensing, it can be achieved that with concrete temperature-library coolant-temperature gage and dam
The a tractor serves several purposes of other fiber-optic monitoring projects such as silt position, reservoir sedimentation before (factory), promotes the replacement of safety monitoring system to upgrade,
It is effectively improved the cost effectiveness of optic-fiber monitoring system.
Detailed description of the invention
Fig. 1 is deformation monitoring optical fiber package board (monitoring board) simplified schematic diagram
Fig. 2 is the construction-shape and cloth of the linearisation weak curved beam type and micro-bend beam type fibre strain monitoring board of arch dam gallery
Set schematic diagram (Fig. 2 a is weak curved beam type monitoring board, Fig. 2 b is micro-bend beam type monitoring board)
Fig. 3 is fibre strain sensing and monitoring system composition schematic diagram
Fig. 4 is that (Fig. 4 a is gallery for the technical solution simplified schematic diagram of the fibre strain monitoring board arrangement of arch dam gallery and vertical shaft
Deformation monitoring plate arrangement, Fig. 4 b be vertical shaft deformation monitoring plate arrange)
Specific embodiment
(1) laying installation of the fiber-optic monitoring plate in gallery and vertical shaft: fiber-optic monitoring plate in gallery and erects in dome dam
The technical solution installed in well such as Fig. 4,15 be fixing bolt in figure, and 16 is lift steel plate strip, and 17 be monitoring vertical shaft, and 18 be radial
Monitoring board, 19 be tangential monitoring board, and 20 be installation operating space.In gallery, such as it in Fig. 4 (a) (13), vertical monitoring board
(to observe along journey arch dam vertical deviation and tangential horizontal displacement) is close to gallery upstream wall and lays installation, top expansion bolt
(or built-in fitting) is fixed, fixing bolt spacing about 0.5~2m.(it in Fig. 4 a (12), observation are along journey arch dam for level monitoring plate
Radially and tangentially horizontal displacement) it is mounted on the bottom of roof arch of gallery, upstream side is solid with expansion bolt (spacing about 0.5~2m)
Fixed, downstream side is lifted with steel plate strip, forms freely-supported seat.Installation exercise carries out control measurement with total station, ensures to be accurately positioned and adjust
It is flat, guarantee the levelness at the top of vertically-arranged plate with horizontal plate；The installation of connector between plate section needs Lao Gu Mi to seal, and micro-pipe alignment is used
The unobstructed and air-tightness of monitoring board micro-pipe is examined in optical fiber air-blowing operation.
In the shaft, such as attached drawing 4 (b), in the Circular Shaft of the typical section of laying optical fiber monitoring, radial monitoring board
The upstream side of (18 in Fig. 4 b) is fixed with expansion bolt (spacing about 0.5~2m), to monitor the vertical of dam body and the dam foundation
Displacement and radial level displacement.Tangential monitoring board (19 in Fig. 4) is fixed on the left of it in the monolith by left bank, leans on right bank monolith
In then fix its right side, to monitor the vertical displacement and tangential horizontal displacement of dam body and the dam foundation.The orthogonal laying of the two, bottom
With appropriate depth is stretched under basement rock vertical shaft, the bottom end concrete build-in of monitoring board forms fixed end, as datum mark.Ditto, installation exercise
In to guarantee accurate positioning, fixation seldom lean on, connector wants micro-pipe to be aligned between each plate section, it is unobstructed and sealing.
(2) monitoring of the displacements such as Rock mass of dam abutment, high slope, slip mass can refer to the above-mentioned arrangement in gallery, vertical shaft
And embodiment lays two-way or single monitoring board, in dam abutment footrill, irrigation gallery, perpendicular (oblique) well or drilling to observe level
Displacement, vertical displacement and the deformation of geology weakness-structural belt etc..
(3) the laying positioning of sensor fibre: after packaging part all the way completely installation positioning, air blow off is used in its micro-pipe
Lay sensor fibre group.Umbrella hat is fastened in the front end of optical fiber, and in the case where calming the anger and blowing, umbrella hat drags optical fiber from one end cloth to another
It holds (transplanting that the technique is telecommunications industry mature technology)；Consolidation positioning of the optical fiber in micro-pipe is carried out using vacuum high-pressure method
(air-blown installation and grouting process of the optical fiber in small diameter conduits, in freeway tunnel concrete is perfused in modified cement mortar
It is verified in the fibre optic installations of lining cutting).
Claims (2)
1. a kind of distributed optical fiber sensing system of induced joint deformation monitoring, it is characterised in that: provide a kind of book of sensor fibre
Plate shape encapsulating structure, the encapsulating structure are fiber-optic monitoring plate；The fiber-optic monitoring plate uses curved shape configuration, including weak curved beam, micro-
Two kinds of patterns of camber beam；By in the footrill of the orthogonal longitudinal gallery for being laid in arch dam of the two and vertical shaft and dam foundation dam abutment, vertical shaft, structure
At the sensing element of three-dimensional Euler's spring beam, realize on-line monitoring dam body, the dam foundation, dam abutment radial, tangential horizontal displacement and hang down
The spatial and temporal distributions state and process being directly displaced；
Using curved optical fiber encapsulating structure, occasion is laid for optical fiber sensing system to adapt to the hyperbolic dam type of induced joint
Specific needs；The construction for taking curved beam control height and camber beam to be segmented realizes the linearisation of curved shape encapsulating structure mechanical property, including
The theory analysis and embodiment of linearization technique and its moulding；The theory analysis of linearization technique is closed based on Elasticity
In the analytic solutions of bend sheet-beam direct stress, the nonlinearity erron expression formula and non-linearization degree quantitative expression of curved beam bending stress
Formula is each are as follows:
δ=ξ -1, (1)
Embodiment and its moulding are the control of curved beam height within the 1~2% of the radius of curvature of the curved beam, to be configured to weak
Curved beam, then the fibre strain monitoring board becomes linear transducer；The monitoring board of plane camber beam is segmented, each section of camber beam central angle is made
≤ 30 °~50 °, becomes micro-bend beam, equally transform into linear transducer；The fibre strain monitoring of weak curved beam and the encapsulation of micro-bend beam
Plate is attributed to Euler's spring beam on mechanics, has enough accuracy and engineering practicability.
2. the distributed optical fiber sensing system of induced joint deformation monitoring according to claim 1, it is characterized in that: in induced joint
In engineering, at the upstream wall of longitudinal gallery of different elevations and crown, each arrangement vertically to horizontally fiber-optic monitoring plate,
Go deep into basement rock at the horizontal rock cave of dam abutment, be made into fixed end, as the datum mark of deformation monitoring, to monitor along journey dam body and dam abutment
Radial, tangential two-way horizontal displacement and vertical displacement；It is vertical to apply in the vertical shaft and its downward batholith vertical shaft of typical section
If orthogonal fiber-optic monitoring plate, using bottom as fixed end datum mark, the monitoring dam body-dam foundation is radial, tangential two-way horizontal displacement and
Vertical displacement；In the dam abutment dam foundation, one-way or bi-directional fiber-optic monitoring plate is laid in irrigation gallery, vertical shaft, footrill or drilling, to see
Survey the sliding deformation of horizontal displacement, vertical displacement and geology weakness structural belt.
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| CN112697997A (en) * | 2020-12-09 | 2021-04-23 | 南京大学 | Slope state inversion method based on distributed optical fiber strain sensing |
| CN112556556B (en) * | 2020-12-21 | 2022-07-01 | 长安大学 | Measuring device and measuring method for deformation of tunnel secondary lining structure |
| CN112964191B (en) * | 2021-03-25 | 2022-11-04 | 四川合众精准科技有限公司 | Micro-deformation laser collimation measurement method |
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