CN105890537A - Distributed fiber optic sensing technology and system for monitoring of deformation of high arch dam - Google Patents

Abstract

The invention discloses a distributed fiber optic sensing technology and a system for monitoring of deformation of a high arch dam, which relate to the field of crossing of a dam safety monitoring technology and a fiber optic sensing technology and are used for overcoming the defect of a conventional means for the monitoring of the deformation of the high arch dam and filling the blank of using distributed fiber optic sensing for the monitoring of the deformation of a dome dam. Aiming at the characteristics and the difficulties of the dome dam, two kinds of unique curved fiber optic packaging structures, namely, fiber optic monitoring panels in a weakly curved beam type and a micro-bending beam type, are provided. Based on error analysis and curved beam height control-camber beam segmentation construction, excellent performance, high reliability, long service life, convenience and practicability of monitoring of fiber optic deformation are ensured. A convenient and practical layout installation mode in an arch dam and a gallery, a vertical shaft and a footrill of a dam foundation is provided, so that online remote metering on multi-dimensional and large-scale time-space broad coverage of three components (radial horizontal displacement, tangential horizontal displacement and vertical displacement) of internal deformation of the arch dam, the dam foundation and a dam abutment is realized. An optical demodulation instrument is multifunctional and can be used for metering concrete temperature, reservoir water temperature, slit level in front of a dam, reservoir sedimentation and the like.

Description

The technical scheme of the distributing optical fiber sensing of induced joint deformation monitoring and system

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, particularly to a kind of high The technical scheme of the distributed optical fiber sensing monitoring of arch dam deformation and system, can realize dam body and the dam of dome dam The on-line monitoring that the various dimensions-space-time of the distributing optical fiber sensing of shoulder dam foundation internal modification extensively covers.

Background technology

The conventional method of arch dam horizontal displacement monitoring, based on normal line method, is located in typical section in dam body, single Section line length about 50m；Multiplex static level is monitored in vertical displacement.Dam foundation dam abutment deformation is monitored multiplex reversed pendulum, is drawn Bracing cable, inclinometer, multipoint displacement meter, indium steel wire displacement meter etc..Wherein, most widely used vertical frontal line, can only Surveying horizontal displacement, function singleness, the construction time is difficult to form observation system；Most equipment need to be with electricity such as the coordinatographs Measurement equipment is observed, and its durability, long-time stability and time between failures are the most barely satisfactory, correction, Change, maintenance load big；Being usually placed in typical section, it is impossible to take into account full dam, quantity of information is few, there is office Portion's property and limitation；Equipment component needs manual site to operate, such as movable inclinometer etc., it is difficult to realize the most distant Survey.These difficult problems are along with the increase of height of dam, and its challenge is the most prominent.

Induced joint commonly uses hyperbolic dam type, Ru Ertan, voe, silk screen, small stream Luo Du dam etc..Arch dam inside is become For shape monitoring, hyperbolic dam type is feature, especially difficult point." hyperbolic " limits tension wire, laser alignment Application etc. means.To this, the innovation effort that industry is recent, is that the dam such as Bai Shan, voe uses fold-line-shaped vacuum The case of laser three-D deformation monitoring ,-according to document [1]-" but its certainty of measurement is the most undesirable, it is impossible to very Good solution versatility monitoring problem "^[1]。

So far, Distributed Optical Fiber Sensing Techniques and system there is no the example for arch dam deformation monitoring and technical side Case, only by distributing optical fiber sensing/quasi-distributed optical fiber sensing FBG (Fiber Bragg Grating FBG) for ground The example of lower engineering, stake work, foundation engineering, pipeline, the model experiment of concrete dam etc. deformation detection.

Cairo, EGY subway 3# line passes through soft soil layer, have employed BOTDA (Brillouin light time domain during excavation Analyze) type fibre strain monitoring pipe, carry out soil layer settlement observation.Sighting tube bright finish circle plastic tube Long 12～20m, tube outer surface lays 3 sensor fibres, by Euler-Bernoulli Jacob's spring beam reason Opinion, show that soil layer is distributed along the sedimentation that test tube is longitudinal, respond well^[2]。

In Shanghai Underground circuit, the encapsulating structure of optical fiber uses commonInclinometer pipe, long 84m.Pipe Respectively open a groove at the bottom of push pipe, glue into FBG.The optical fiber measured value of sedimentation is consistent substantially with contrast measured value^[3]。

In Hong Kong New Territories landslide, long 15m'sIn 4 symmetrical grooves of inclinometer pipe, respectively install 10 FBG, usesBoring embedment stratum, cement mortar build-in.Observations in 480 days of its horizontal distortion Data, are consistent substantially with conventional inclinometer pipe result^[4]。

Nanjing one deep basal pit, is pasted onto sensor fibre in the groove of symmetrical both sides of pvc pipe, its side court To foundation pit walls, with the boring vertically other soil layer in embedment hole, deep 32m.With BOTDR (Brillouin light in excavation Time Domain Reflectometry) record this pipe deflection deformation, i.e. earth horizontal displacement, meet well with total powerstation measured value^[5]。

Spoil power plant, Shanxi, to diameter 800mm, long 31m, 35m bored concrete pile, passes by Brillouin's type Photosensitive fibre, detects pile body amount of deflection, strain in static test.Sensor fibre 2 curb pile body lateral symmetry is arranged, Obtain full and accurate achievement.

Near Italy Rimini, gas pipeline is about 500m, passes with the brillouin distributed optical fiber of BOTDA Sense monitoring steel pipe along the strain of journey and deformation, application indicate the measurement stability of this technology, long-term reliability and Distributed remote power of test^[6]。

In the concrete gravity dam model test of Wudu, Sichuan, by FBG strain gauge, it is bonded in the X-Y on plastics round bar surface On line of symmetry, constitute FBG sensor bar,The long 50cm of bar.A bar is respectively buried in dam body-dam foundation, Theoretical, by the vertically and horizontally horizontal displacement of round bar sag detection model, with displacement meter school mutually by Euler's spring beam Testing, measured value meets well^[7]。

Visible, distributed optical fiber sensing monitoring deforms, and the most at home and abroad in some close engineering fields, obtains Preliminary Applications, it is shown that effectively practicality.The industry common recognition in this field is: the core of distribution type fiber-optic deformation sensing The heart and difficult point, be optical fiber and by the interface (Interface) between geodesic structure^[8].Employing generally described above The encapsulating structure of elongated beam type is as interface.Packaging part protects in its fiber package, exempts the same of damage Time, especially play a part sensing element (pre-converter), the deformation of tested engineering, be converted into encapsulated beam The strain of body, in order to optical fiber perception.I.e. optical fiber elongated straight-bar/straight tube encapsulation, records the distribution of tension and compression side strain, Its deflection deformation and linear deformation is determined by euler beam theory.

When the fibre strain monitoring technology of existing engineer applied, when being transplanted to arch dam engineering, key issue is: Rectilinear fiber package structure (straight beam), it is difficult to adapt to hyperbolic dam shape；Must propose to be suitable to the reality of dome dam The new technical scheme of the shape of shaped form encapsulating structure, structure and precision analysis；Also want corresponding Certainly optical fiber sensing system Layout Problem in induced joint；Optimize the (FBG) demodulator choosing of fibre strain monitoring system Type.

The technical problem to be solved is, overcomes the defect of the conventional equipment of induced joint deformation monitoring and divides Cloth Fibre Optical Sensor is for the blank of dome dam deformation monitoring, it is provided that one adapts to dome dam particular demands , the induced joint with engineering practicability deform the technical scheme of online remote measurement and system.

Main literature: [1] Huang Huibao, Jiang Hua is expensive, Zhang Zebin, great writer. vacuum laser Huaihe River is directly at Pubugou hydropower Application in the big displacement quantity monitoring of power station. the 3rd rock-fill dams international symposium collection of thesis, October 25 in 2013 Day, China Kunming, pp:891-895. [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 3^rd 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 4^th Int.Forum on Opto-electronic Sensor-based Monitoringin Geo-engineering, Oct.11-13,2012. [5] Liu Outstanding person, Shi Bin etc. foundation pit deformation distributed monitoring experimentation [J] based on BOTDR. rock-soil mechanics, 2006, 27(7).[6]D.Inaudi.Field application of strain and temperature fiber optic sensors [C], Proc.of 2^nd 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.3^th 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 of technical scheme institute foundation

This patent belongs to hydraulic engineering and the large span as high-tech two technical fields of Fibre Optical Sensor is intersected Merging, 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 scattering, all to strain and two kinds of mechanical quantity sensitivities of temperature^[9～11].Two intrinsic scatterings are the most distinctive It is as follows with the information carrier of temperature that optical parameter becomes strain:

1) Brillouin (Brillouin) scattered light--the frequency displacement of brillouin gain spectrum peak and temperature and strain Increment linear correlation, basic relational expression is:

Δv_b=C₁₁Δε+C₁₂ΔT (1)

In formula, Δ v_bFor brillouin gain spectrum frequency displacement, Δ ε is strain increment, and Δ T is temperature increment, C₁₁For Brillouin's strain-coefficient of frequency, C₁₂For Brillouin's temperature-frequency coefficient.By measuring brillouin frequency Move and just can measure fibre strain and temperature, the optical fiber Temperature Distribution along journey can be obtained through decoupling.Novel is pre- Pulse (Pulse-Pre-Pump) Brillouin optical time domain analysis instrument PPP-BOTDA, its pulse minimum width Degree reaches 0.2ns, and space point variability reaches 2～10cm, certainty of measurement 7.5 μ ε/0.35 DEG C.

2) Rayleigh (Rayleigh) scattered light--the residual strain institute that fiber core generates in pulling process The Rayleigh beacon light produced, its frequency displacement and temperature and strain increment linear correlation, basic relational expression For

Δv_R=C₂₁Δε+C₂₂ΔT (2)

In formula, Δ v_RFor Rayleigh scattering optical frequency shift, C₂₁For Rayleigh strain-coefficient of frequency, C₂₂For Rayleigh temperature Degree-coefficient of frequency.Brillouin-Rayleigh synthesis system (Hybrid Brillioun-Rayleigh system) is near Phase commercialization-TW-COTDR already (harmony wavelength Coherent optical time domain reflectometer), service behaviour with Above-mentioned PPP-BOTDA is suitable, and can realize the automatic decoupling of temperature-strain.These are raising system Signal to noise ratio, strengthen observation data reliability provide urgently advantage.

(2) theory of mechanics

1) straight beam--in elastic theory, for Euler-Bernoulli Jacob's three dimensional elasticity beam theory of uiform section straight beam The basic assumption of model is: beam body is homogenizing linear elastic materials；Amount of deflection belongs to small deformation relative to span；Cut Face remains plane after deformation；Detrusion is ignored；The additional bending moment of axial force is ignored；Beam Body is not by moment of torsion.The distribution of tension and compression side strain and its deflection deformation one_to_one corresponding of beam, the most long-pending through strain Point, amount of deflection can be tried to achieve；Multiple integral to strain mean, obtains the linear deformation of beam.

2) the circumference stress σ of bend sheet-beam--the pure bending of planar arc curved beam_θExpression formula is^[12]

${\mathrm{\σ}}_{\mathrm{\θ}}=\frac{4M}{N}(-\frac{a^2{b}^2}{r^2}ln\frac{b}{a}+b^{2}ln\frac{r}{b}+a^{2}ln\frac{a}{r}+b^2-a^2)---\left(3\right)$

In formula, a is curved beam inside radius, and b is curved beam outer radius, and r is polar coordinate radius vector, and θ is argument, M For moment,

Obviously, tangential stress presents log series model along depth of section, hence it is evident that the cross section in the case of deviation straight beam should , there is non-linear effects and error in the linear distribution of power.

3) plane camber beam--the Common examples of plane camber beam, the camber beam used in bridge as curved in highway；At arch In dam monitoring, the monitoring board (accompanying drawing 2 they (13)) of the setting in gallery just belongs to this kind of knot Configuration formula.Its mechanics feature is: the vertical load that beam body is born is while producing vertical bending moment, also It is associated with horizontal moment of torsion.This bending-twisted coupling, causes the distortion of beam body stress-deformation, leads Causing non-linear, moment of torsion can produce additional amount of deflection^[13]。

Main literature: [9] Fang Zujie etc. Fundamentals of Fibre Optical Sensors [M]. Beijing: 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 Changjun, Wang Ying Hard etc. Elasticity [M]. Beijing: Higher Education Publishing House, 1999；[13] He Shuanhai, bridge structure is managed Opinion and computational methods [M]. Beijing: People's Transportation Press, 2003.

(2) technical scheme

(1) primitive form of sensor fibre encapsulating structure is deformed

The shape of encapsulating structure is light and practical with structure, for the one-tenth of the engineer applied of fibre strain monitoring Lose, there is decisive role.The fiber package structure of aforementioned existing deformation monitoring, in respect of pipe, Two kinds of forms of round bar, are circular cross-section.Induced joint project scale is big, rigidity is big.If optical fiber Encapsulation is with this circular cross-section beam, and for providing the sensing sensitivity of necessity, its diameter about 1～2m (is subject to The main border strain value of camber beam body is directly proportional to deck-molding), take up room big, it is difficult to utilize conventional dam Interior gallery, is arranged installing.

To this end, for the application scenario of dome dam, this patent follows dimensionality reduction (Dimension reduction) Design, it is provided that book template encapsulating structure-the narrow rectanglar girder of a kind of sensor fibre, i.e. optical fiber prison Drafting board ellbeam, such as Fig. 1, wherein 1 is sensor fibre, and 2 is transmission cable, and 3 is optical signal demodulation instrument, 4 is package board, and 5 is the fixed end of package board, and 6 is micro-pipe.Respectively set in both sides, package board long limit 1 micro- Pipe (diameter about 15mm), to lay sensor fibre group, (route of both sides micro-pipe inner fiber is U-shaped (U-shaped thin portion is the most not shown)), as the plate shape Euler's beam body tension and compression side when bending, Form fibre strain monitoring board ellbeam, referred to as fiber-optic monitoring plate or monitoring board.Fiber-optic monitoring plate ellbeam Height be about 0.5～2m.The composition of the sensor fibre group in every micro-pipe is, when optical signal demodulation instrument When selecting BOTDA type, with 3～4 tight set sm fibers plus 2 loose tube fibers (for temperature Compensate)；When Brillouin-Rayleigh synthesis system selected by optical signal demodulation instrument, then use 3～5 tight sets Sm fiber.

Sensor fibre in each micro-pipe, can be along strain (and temperature) continuous function of the one-dimensional space of journey. When monitoring board is vertically arranged, its end is fixed, the two dimension becoming narrow and long rectangular section is cantilever spring Beam, can observe 2 deformation component simultaneously: the amount of deflection of plate ellbeam and linear deformation thereof.When monitoring board water Plain cloth puts-and end is when fixing, and its amount of deflection occurs in horizontal plane.It is clear to, monitors two along a survey line Plate is orthogonal to be laid, deformation 3 component (i.e. vertical displacement, the radial level that the most considerable drafting board ellbeam is along the line Displacement, tangential horizontal displacement).

(2) linearisation configuration and the technical scheme of analysis thereof of package board ellbeam are bent

The key of the feasibility-practicality of Curved package board ellbeam scheme, is its linearity.Linear sensing Device is preferable sensor, and bend sheet-beam and camber beam all exist on mechanics non-linear.Non-linear not Only increase the error of sensor, and make observation data analysis complicate, time-consuming bothersome.For solving this One key problem, now provides corresponding quantitative analysis and error estimation, and then proposes its linearisation (Linearization) technical scheme of configuration.So-called linearisation configuration, it is simply that build the micro-of exquisiteness Bending packaging part, had not only adapted to the mounting location of hyperbolic dam type, but also can eliminate the impact of nonlinearity erron, It is allowed to transform into linear transducer, and enough degree of accuracy can be kept.

1) straight beam: the non-linear factor of straight beam is usually predominantly the shearing in shear bending, lures beam section into Warpage.Using evenly load square-section simply supported beam as typical case, the parsing of straight beam direct stress σ distribution Solution expression formula is^[12]

$\mathrm{\σ}=\frac{3qy}{4{\mathrm{bh}}^3}(x^2-\frac{L^2}{4})+\frac{qy}{2{\mathrm{bh}}^3}(\frac{3}{5}{h}^2-y^2)={\mathrm{\σ}}_M+{\mathrm{\σ}}_Q---\left(4\right)$

In formula, b is deck-siding, and h is deck-molding, and L is span, and y is that to natural axis distance, (x-y sits stress point Mark initial point is at the span centre point of beam axis), q is evenly load intensity；σ_MThe direct stress produced for moment of flexure, I.e. previous item in formula (4), σ_QThe direct stress produced for shearing, i.e. latter in formula (4). According to formula (4), it is not difficult to derive the σ of spaning middle section_QWith σ_MRatio ζ be

$\mathrm{\ζ}=\frac{{\mathrm{\σ}}_Q}{{\mathrm{\σ}}_M}=\frac{4}{15}{\left(\frac{h}{L}\right)}^2---\left(5\right)$

The nonlinearity erron that the shearing factor of the freely-supported spring beam of different span-depth radios produces, such as table 1.

Table 1

Result shows: as long as packaging part is the most elongated, span-depth radio >=5～10, the nonlinearity erron that shearing produces The least, beam section stress keeps linear distribution, and the most elongated straight beam is as sensibility elasticity element, and it is linear Splendid.

2) bend sheet-beam: curved beam is different from the mechanical characteristics of straight beam and is, Euler-Bernoulli Jacob's cutting plane supposes one As be false^[12], i.e. at the stress linear distribution of straight beam, then change into non-linear (logarithm) at curved beam Distribution, such as formula (3), the strengthening of concave edge fiber stress deformity, absolute value exceedes flange stress value.In view of This, for quantitative analysis meter, with the ratio of rabbet fiber stress, characterize the non-linearization of curved beam stress distribution Degree.

If concave edge fiber stress isFlange stress isThe ratio of the two absolute value isLinear distribution situation at straight beam, it is clear that have: a=b, and ξ=1.Cut The nonlinearity erron δ that the log series model state of face stress causes is represented by

δ=ξ-1 (6)

At curved beam, if b=λ a, be apparent from λ=1+h/a, i.e. λ contain deck-molding h ratio in interior half The relative deck-molding of footpath a.

According to formula (3), through being derived from

$\mathrm{\ξ}=\frac{{\mathrm{\λ}}^2(1-2ln\mathrm{\λ})-1}{{\mathrm{\λ}}^2-2ln\mathrm{\λ}-1}---\left(7\right)$

The Non-Linear Error Analysis result of the different deck-moldings relatively of bend sheet-beam, such as table 2.

Table 2

Result shows: as long as the deck-molding of curve monitoring board ellbeam, control within the 2～3% of inner radius values, The nonlinearity erron that then its curved beam shape causes be less than 1%～3%, foot requirement of engineering precision, that is Nonlinearity erron is negligible, and directly uses Euler's straight beam mechanical model and deflection deformation algorithm.

3) plane camber beam: achievement in research shows, when central angle≤30 of plane camber beam～50 °, can omit torsion Turn additional deflection, be reduced to straight beam buckling problem and the most accurate^[13], the curved bridge of substantial amounts of highway Engineering practice also demonstrate that this point.

Comprehensive above error analysis result and relevant achievement, it is provided that the structure side of curved beam control height-camber beam segmentation Formula, as in figure 2 it is shown, 7 be arch ring in figure, 8 is gallery, and 9 is dam abutment footrill, and 10 is on gallery You Bi, 11 is roof arch of gallery, and 12 is level monitoring plate, and 13 is vertical monitoring board, and 14 is monitoring board Fixed end.Fig. 2 a is gallery cross section, and Fig. 2 b is the A-A section of Fig. 2 a, and display is at roof arch of gallery The upper viewing view of the curved beam type monitoring board 12 that place is laid；Fig. 2 c is the B-B section of Fig. 2 a, display It is close to the upper viewing view of the camber beam-type monitoring board 13 that gallery upstream wall is laid.Thus, it is configured to The linearizing spring beam sensing element of the weak bending of following two:

A) weak curved beam (Weakly curved beam)-the radius of curvature of induced joint normal about 100～500m, Deck-molding selects 0.5～2.5m (the layout peace that this deck-molding also allows in gallery, footrill, vertical shaft Dress), it is possible to deck-molding is controlled (λ≤1～2%), non-thread within the 1～2% of curved beam radius Property error the most about 1%, not significant, thus on mechanical mode, become Euler's type straight beam.

The center of maximum angle of b) micro-bend beam-the induced joint that China builds up and designs is mostly not less than 100 °^[9].To this end, for the camber beam packaging part of the big arch ring of central angle, with the configuration of segmentation, will Crossing over the camber beam of full arch circle, disconnect in arch centerline, about formation, two single fixed end cantilevers are curved Beam, its respective central angle is only arch ring half central angle, it is possible to the mechanics bar of the linear camber beam of foot Part (central angle≤30～50 °), the non-linear effects of negligible moment of torsion^[13], on mechanical mode Also Euler's type straight beam is become.

Monitoring board ellbeam in vertical shaft is similar with this, also comprises linearizing weak curved beam-along river to monitoring board (they (18) in Fig. 4 b) and linearizing micro-bend beam-Yokogawa is to monitoring board (they (19) in Fig. 4 b). The beam of arch dam is typically the least to central angle, and the micro-bend beam in vertical shaft readily satisfies central angle≤30～50 ° Condition.

(3) technical scheme of the layout of induced joint fibre strain monitoring

1) layout of gallery fiber-optic monitoring plate

Induced joint dam body is set up and is equipped with multilamellar Vertical Curve shape gallery, preferably as full dam fiber-optic monitoring plate Primarily arrange occasion.Monitoring board is arranged in longitudinal gallery of different elevation, exists monitoring full arch dam The horizontal displacement of each corresponding elevation and vertical displacement.Concrete position is: (1) vertically monitoring is smooth in corridor Road upstream wall (they (10) in Fig. 4 (a)), is fixed on its top on concrete wall (as with expansion along journey Bolt (or built-in fitting)), in order to monitor the vertical displacement of dam body along the line and tangential horizontal displacement；(2) Level monitoring plate is laid in gallery dome portions, is fixed along journey by its upstream side, in order to observe respectively this elevation Dam body radially, transverse horizontal displacement.The end of both monitoring boards, by the footrill of suitable length, Go deep at mother rock of dam shoulder certain depth, and make fixed end, as monitoring board datum mark (in Fig. 2 it (14))。

2) layout of vertical shaft fiber-optic monitoring plate

In the vertical shaft on the dam, close upstream of typical section, the monitoring board of orthogonal is vertically arranged, as Fig. 4 (b).The boring of its bottom surface or excavation, downwardly extend, go deep at basement rock appropriate depth, bottom Make fixed end datum mark.Repeatedly segmentation from the vertical line of routine monitoring is different, here, vertical shaft and Monitoring board is along smoothed curve, from basement rock deep datum mark, extends the most continuously, until dam crest. Radially monitoring board is fixed on the upstream side borehole wall of vertical shaft along journey；Tangential monitoring board at arch crown with left dam Duan Zhong, is fixed on the left of it on the borehole wall；At arch crown in right monolith, to be then fixed on the right side of it On the borehole wall, it is intended to form the top loading environment of Euler's spring beam.In monitoring dam body horizontal displacement, scratch Degree and vertical displacement while, also can observe the dam foundation sedimentation, vertical along journey dam body upstream face concrete Should be distributed and change in time and space.

3) the internal modification monitoring of dam abutment Dam Foundation Rock

First being to utilize two sides irrigation gallery, monitoring board arrangement is similar to corridor in dam, can excavate if desired Rock cave (or boring), lays the unidirectional or monitoring board of orthogonal.At monitoring rock mass Three-direction deformation While, also can monitor each structure, the deformation of structural belt and the changing of the relative positions passed through.

4) technical scheme of fibre strain monitoring system composition

The composition of fibre strain monitoring system, is shown in accompanying drawing 3, specifically includes that sensor fibre 1-transmission cable 2- Optical signal demodulation instrument 3 (main control computer, UPS etc. accessory is not shown).

Wherein, PPP-BOTDA (the prepulsing Brillouin light time-domain detection that optical signal demodulation instrument is the most novel Instrument), its pulse minimum widith reaches 0.2ns, and space point variability reaches 2～10cm, strains precision 7.5 μ ε, Straining repeated 5 μ ε, temperature accuracy reaches 0.35 DEG C, measures time 5s, distance range 50m～10km, It is suitable for sm fiber.The instrument TW-COTDR that solves of Brillouin-Rayleigh synthesis system also reaches similar Performance, and strain-temperature two parameter can decouple voluntarily.

For under the conditions of engineering site verify PPP-BOTDA type optical fiber sensing system performance, 2011 The on-the-spot static loading experiment of Xi'an PHC stake and strain actual measurement, carried out domestic technical identification first, Well-known Switzerland's slide attack is used to check.PHC stake diameter 500mm, the long 30m of stake, In pile body, imbed two-way strain sensing optical fiber, imbed slide attack, test pile static load together 693～1464kN.The strain measured value of two kinds of means of result is consistent substantially, and [the grand .PPP-BOTDA in river is distributed Formula optical fiber sensing technology and application [J] in test pile thereof. rock-soil mechanics, 2011,32 (10): 3190-3195]。

(4) beneficial effect of technical scheme

1) multiple systems of the principle/different properties of the conventional equipment of arch dam internal modification monitoring, is simplified For single optical fiber sensing system；Monitoring system is highly simplified, extremely refine, eliminates movable member, Significantly economization maintenance load, significantly improves the signal to noise ratio of system, conscientiously ensures the length of observation data Phase reliability and stability, makes the advanced and applicable high-tech means with practical value.At optical fiber At the initial stage of Application in Sensing, complement each other with routine monitoring means, mutually confirm, when significantly improving The effectiveness of dam safety monitor system and scientific and technological level, it is expected to become induced joint safety monitoring field One of high-tech means.

2) on-the-spot artificial measuring point, manual operations are eliminated, it is simple to realize real-time online remote measurement.

3) monitoring of high dam internal modification is risen to networking/integrated horizontal, be beneficial to realize the deformation of full dam and see (normal line method in conventional equipment can only be arranged in minority monolith, it is difficult to takes into account complete in the space-time all standing surveyed Face).In monitoring time overall process, optical fiber sensing system i.e. buries i.e. to be surveyed (particularly in gallery-grotto Monitoring board), construction time data will not lack, set up meet reality displacement initial fields；Construction time Monitoring system can fast access later stage automated system, will not data interruption.

4) optical fiber sensing system corrosion-resistant, anti-lightning strike, without electromagnetic interference, without abrasion, waft almost without zero, Steady operation many decades, maintenance load is minimum；Long-life-highly reliable.Optical fiber sensing system is correlated with material The price reduction of material equipment is fast, performance improves fast, and development potentiality is big.

5) optical signal demodulation instrument has distributed temperature sensing function, can realize with concrete temperature-storehouse coolant-temperature gage with And a tractor serves several purposes of other fiber-optic monitoring projects such as dam (factory) front silt position, reservoir sedimentation, promote peace The replacement upgrading of full monitoring system, is effectively improved the cost effectiveness of optic-fiber monitoring system.

Accompanying drawing explanation

Fig. 1 is deformation monitoring fiber package plate (monitoring board) simplified schematic diagram

Fig. 2 be the linearisation weak curved beam type of arch dam gallery and the structure-shape of micro-bend beam type fibre strain monitoring board and Arrangement schematic diagram (Fig. 2 a be weak curved beam type monitoring board, Fig. 2 b be micro-bend beam type monitoring board)

Fig. 3 is that fibre strain sensing and monitoring system forms schematic diagram

Fig. 4 be arch dam gallery and vertical shaft fibre strain monitoring board arrange technical scheme simplified schematic diagram (Fig. 4 a is The deformation monitoring plate that the deformation monitoring plate of gallery is arranged, Fig. 4 b is vertical shaft is arranged)

Detailed description of the invention

(1) fiber-optic monitoring plate laying installation in gallery and vertical shaft: in dome dam, fiber-optic monitoring plate is at gallery With the technical scheme such as Fig. 4 installed in vertical shaft, in figure, 15 is fixing bolt, and 16 for lifting steel plate strip, 17 is monitoring vertical shaft, and 18 is radial direction monitoring board, and 19 is tangential monitoring board, and 20 for installing working place. In gallery, such as they (13) in Fig. 4 (a), vertical monitoring board is (vertical in order to observe along journey arch dam Displacement and tangential horizontal displacement) it to be close to gallery upstream wall and lay and install, top is (or pre-with expansion bolt Embedded part) fixing, fixing pitch of bolts about 0.5～2m.Level monitoring plate (they (12) in Fig. 4 a, Observe along the radially and tangentially horizontal displacement of journey arch dam) it is arranged on the bottom of roof arch of gallery, its upstream side Fixing with expansion bolt (spacing about 0.5～2m), downstream steel plate strip lifts, and forms freely-supported seat. Installation exercise total powerstation be controlled measure, ensure be accurately positioned leveling, it is ensured that vertically-arranged plate top and The levelness of horizontal plate；The installation of the joint between plate section need to firmly be sealed, and micro-pipe is directed at, and uses optical fiber Air-blowing operation, the unobstructed and air-tightness of the inspection micro-pipe of monitoring board.

In the shaft, such as accompanying drawing 4 (b), in the Circular Shaft of the typical section of laying optical fiber monitoring, footpath Fix to the upstream side of monitoring board (in Fig. 4 b 18) expansion bolt (spacing about 0.5～2m), In order to monitor vertical displacement and the radial level displacement of dam body and the dam foundation.Tangential monitoring board (in Fig. 4 it 19) fix on the left of it in the monolith of bank that keeps left, bank monolith of keeping right then is fixed on the right side of it, in order to supervise Survey dam body and the vertical displacement of the dam foundation and tangential horizontal displacement.The two orthogonal laying, uses basement rock bottom it Appropriate depth is stretched under vertical shaft, the bottom of monitoring board concrete build-in, form fixed end, as datum mark.With Before, accurate positioning to be ensured in installation exercise, fixing seldom to lean on, between each plate section, micro-pipe alignment wanted by joint, Unobstructed and seal.

(2) monitoring of the displacement such as Rock mass of dam abutment, high slope, slip mass, refers to above-mentioned in gallery, vertical shaft Layout and embodiment, at dam abutment footrill, irrigation gallery, perpendicular (tiltedly) well or hole, lay Two-way or single monitoring board, to observe horizontal displacement, vertical displacement and the change of geology weakness-structural belt Shape etc..

(3) sensor fibre lay location: after a road packaging part installs location completely, in its micro-pipe, use gas Blowing method lays sensor fibre group.Umbrella hat is fastened in the front end of optical fiber, and under calming the anger and blowing, umbrella hat drags Dynamic optical fiber from one end cloth to the other end transplanting of telecommunications industry maturation process (this technique be)；Optical fiber exists Consolidation location in micro-pipe, uses vacuum high-pressure method, and (optical fiber is little to be modified cement mortar perfusion Air-blown installation in diameter pipe and grouting process, the most optical fiber at freeway tunnel concrete-liner apply It is verified in if).

Claims (4)

1. the technical scheme of the distributing optical fiber sensing of an induced joint deformation monitoring and system, it is characterised in that: carry For the encapsulating structure of the book plate shape of a kind of sensor fibre, i.e. fiber-optic monitoring plate ellbeam (fiber-optic monitoring plate)； Particularly this fiber-optic monitoring plate is adopted as curved configuration, including weak curved beam, two kinds of patterns of micro-bend beam； By in the two orthogonal longitudinal gallery being laid in arch dam and vertical shaft and the footrill of dam foundation dam abutment, vertical shaft, structure Become the sensing element of three-dimensional Euler's spring beam, may be implemented in the radial direction of line monitoring dam body-dam foundation dam abutment-tangential The spatial and temporal distributions state of horizontal displacement and vertical displacement and process；Fibre Optical Sensor signal (FBG) demodulator is the most high-precision Degree Brillouin optical time domain analysis system or Brillouin-Rayleigh synthesis system.

The technical scheme of the distributing optical fiber sensing of induced joint deformation monitoring and system the most according to claim 1, It is characterized in that: encapsulation book plate profile structure-the narrow rectanglar girder of sensor fibre, in its both sides, long limit Respectively set 1 micro-pipe (diameter about 15mm), to lay sensor fibre group, exist as plate shape Euler's beam body Tension and compression side during bending, forms fibre strain monitoring 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, its span-depth radio >=5～10；Sense light in every micro-pipe The composition of fine group is, when BOTDA type selected by optical signal demodulation instrument, with 3～4 tight set sm fibers Add 2 loose tube fibers；When Brillouin-Rayleigh synthesis system selected by optical signal demodulation instrument, then use 3～5 Bar tightly overlaps sm fiber.

The technical scheme of the distributing optical fiber sensing of induced joint deformation monitoring the most according to claim 1 or claim 2 and be System, is characterized in that: use curved fiber package structure, with adapt to the hyperbolic dam type of induced joint for Optical fiber sensing system lays the specific needs of occasion；Take the high structure with camber beam segmentation of curved beam control, it is achieved The linearisation of the mechanical property of shaped form encapsulating structure, including theory analysis and the embodiment party of linearization technique Case and moulding thereof；Based on Elasticity about the analytic solutions of bend sheet-beam direct stress, curved beam bending stress non- Linearity error expression formula and non-linearization degree quantitative expression formula are respectively

δ=ξ-1 (6)

$\mathrm{\ξ}=\frac{{\mathrm{\λ}}^2(1-2ln\mathrm{\λ})-1}{{\mathrm{\λ}}^2-2ln\mathrm{\λ}-1}---\left(7\right)$

Embodiment is, curved beam Altitude control within the 1～2% of the radius of curvature of this curved beam, be configured to weak Curved beam, then this fibre strain monitoring board becomes linear transducer；The monitoring board segmentation of plane camber beam, make Each section of camber beam central angle≤30 °～50 °, become micro-bend beam, transform into linear transducer equally；Weak song Beam and the fibre strain monitoring board of microbend encapsulation, be attributed to Euler's spring beam on mechanics, and have foot Enough degree of accuracy, possess engineering practicability；Package board (beam) is fixed end by one or both ends, is arranged on dam In, by Euler's spring beam algorithm, monitoring deformation along the line two components---amount of deflection in the midplane of packaging part and Its linear deformation；With the two orthogonal layings of fiber-optic monitoring plate, then monitor it and deform three-component along the line.

4. according to the technical scheme of the distributing optical fiber sensing of the induced joint deformation monitoring described in claim 1 or 3 and System, is characterized in that: in induced joint engineering, at the upstream wall of longitudinal gallery and the crown of different elevations Place, each arrange vertically to horizontal direction fiber-optic monitoring plate, at dam abutment, employing horizontal rock cave gos deep into basement rock, Make fixed end, as the datum mark of deformation monitoring, with monitoring along radial direction-tangential double of journey dam body and dam abutment To horizontal displacement and vertical displacement；In the vertical shaft and downward batholith vertical shaft thereof of typical section, vertical deposited If orthogonal fiber-optic monitoring plate, with bottom for fixed end datum mark, monitoring radial direction-tangentially dam body-dam foundation is double To horizontal displacement, vertical displacement.In the dam abutment dam foundation, apply in irrigation gallery, vertical shaft, footrill or boring If unidirectional or bidirectional optical fiber monitoring board, to observe horizontal displacement, vertical displacement and geology weakness-structural belt The deformation such as the changing of the relative positions；Each road fiber-optic monitoring plate lay through in place after, the sensor fibre air-blowing of each micro-pipe Method is laid, and with vacuum high-pressure method perfusion property cement mortar, carries out consolidation location.