CN207074097U - A kind of monitoring device and monitoring system of country rock three-dimensional turbulence stress field - Google Patents
A kind of monitoring device and monitoring system of country rock three-dimensional turbulence stress field Download PDFInfo
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- CN207074097U CN207074097U CN201720754631.1U CN201720754631U CN207074097U CN 207074097 U CN207074097 U CN 207074097U CN 201720754631 U CN201720754631 U CN 201720754631U CN 207074097 U CN207074097 U CN 207074097U
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Abstract
This application discloses a kind of monitoring device and monitoring system of country rock three-dimensional turbulence stress field.Monitoring device, including：Housing, in tube structure, the housing is interior outer double-layer structure, and the modulus of elasticity of internal layer and cladding material is 8 15GPa, tensile strength is not less than 60MPa；The mutually different fiber grating at least six directions, it is laid between the internal layer of the housing and outer layer, and the grid region length of the fiber grating is 2 4mm.Pass through the double layer design to shell structure, the restriction to case material and the selection of the grid region length to fiber grating, not only realize under long-term to the accurate measurements of country rock three-dimensional turbulence stress field, and substantially increase the survival rate of fiber grating, allow the monitoring device using fiber grating measurement country rock three-dimensional turbulence stress to realize industrialization production, worldwide fill up the field existing technological gap always.
Description
Technical field
The disclosure relates generally to technical field of measurement and test, and in particular to the underground engineering such as ground, mining stress survey technology is led
Domain, more particularly to a kind of monitoring device and monitoring system of country rock three-dimensional turbulence stress field.
Background technology
With the increase of exploitation of coal resources depth and mining rate, bump has turned into home and abroad colliery exploitation field face
One of major casualty faced.Mining engineering particularly colliery, geological environment and stress condition are complicated, and tunnel or working face country rock exist
Under high-ground stress and strong off-load collective effect, mining induced stress redistribution, time-space relationship is complicated, high stress release, transfer, transmits
The dynamic characteristic of caused coal and rock is obvious, will cause bump dynamic disaster under certain condition, have a strong impact on work
Journey construction speed and safety, often result in construction equipment damage and great personnel casualty accidentses.Early stage occurs for bump, in coal petrography
Energy does not discharge, but internal stress concentration degree has the phenomenon increased suddenly.Therefore the generation of disaster is embodied in answers first
In the change of power state, stress variation is to predict the key of dynamic disaster, and the measurement of stress state is to realize that dynamic disaster is accurate
The basis of forecast.The evolutionary process that stress state in digging process is built with analysis project is obtained by scene, can be effectively real
The early warning and control of existing disaster.Therefore, coal and rock stress test turn into mining activities in dynamic disaster study important content it
One.
Two classes are broadly divided into for the stress test in coal and rock：Not by the protolith detecting earth stress of Engineering Disturbance and construction
During Disturbance stress test.The former has stress relief by borehole overcoring technique, hydraulic fracturing etc. at more ripe test；The latter disturbs
The representative art of stress test is unidirectional borehole stressmeter, and the measurement of wherein bump belongs to Disturbance stress measuring technology neck
Domain.
However, above-mentioned prior art has the following disadvantages：
In underground monitoring early warning bump, it is necessary to bury sensing in the roof strata of ventilation or haulage drift in advance
Device, with propulsion of the work towards sensing station is exploited, the change of roof strata Disturbance stress is monitored, and then to bump
It is predicted and early warning.Since the monitoring and warning cycle typically tie after exceeding the segment distance of monitoring surface one to working face sensor is embedded
Beam, it will typically continue more than ten days to the several months, and it is higher that this just can realize that dynamic long term monitoring proposes to monitoring device
Requirement.And current three-dimensional rock stress test sensor is only capable of realizing the short-term measurement of one to two days, surveyed when for a long time
Severe deviations occur in measurement data during amount, can not obtain accurate measurement result, can not realize the long-term measurement of crustal stress；Separately
On the one hand, the three-dimensional measurement technology of Disturbance stress only exists in the exploratory stage of laboratory level, it is impossible to meets industrialized production
It is required that.Therefore in the prior art, the dynamic long term monitoring of bump triaxiality evolutionary process under underground space complex environment
It is extremely difficult, technological gap always be present in the field in the industry.
Utility model content
In view of drawbacks described above of the prior art or deficiency, it is expected to provide a kind of monitoring dress of country rock three-dimensional turbulence stress field
Put and monitoring system.
In a first aspect, the embodiment of the present application provides a kind of monitoring device of country rock three-dimensional turbulence stress field, including：
Housing, in tube structure, the housing is interior outer double-layer structure, and the modulus of elasticity of internal layer and cladding material is 8-
15GPa, tensile strength are not less than 60MPa；
The mutually different fiber grating at least six directions, it is laid between the internal layer of the housing and outer layer, described
The grid region length of fiber grating is 2-4mm.
Second aspect, the embodiment of the present application additionally provide a kind of monitoring system of country rock three-dimensional turbulence stress field, including upper
The monitoring device for the country rock three-dimensional turbulence stress field stated,
Also include terminal device, wavelength demodulation device and direction finder, the fiber grating passes through the wavelength demodulation device and institute
Terminal device connection is stated, the direction finder is connected with the terminal device；
The terminal device obtains the fiber grating by the wavelength signals of the fiber grating and corresponds to answering at measuring point
Become data, the terminal device obtains the azimuth information of the fiber grating according to the direction finder；
The terminal device is according to the modulus of elasticity and Poisson's ratio of the fiber grating preservation body and the fiber grating
Azimuth information, the strain data is converted to the Disturbance stress data of country rock, and then obtain the stress state at measuring point.
The monitoring scheme for the country rock three-dimensional turbulence stress field that the embodiment of the present application provides, by being set to the bilayer of shell structure
Meter, the restriction to case material and the selection of the grid region length to fiber grating, not only realize under long-term to country rock three
The accurate measurements of disturbance stress field are tieed up, and substantially increase the survival rate of fiber grating so that are enclosed using fiber grating measurement
The monitoring device of rock three-dimensional turbulence stress can realize industrialization production, and it is existing always worldwide to have filled up the field
Technological gap.
Brief description of the drawings
By reading the detailed description made to non-limiting example made with reference to the following drawings, the application's is other
Feature, objects and advantages will become more apparent upon：
Fig. 1 is the Organization Chart of the stress test system of the utility model embodiment one；
Fig. 2 is the structural representation of the stress test device of the utility model embodiment one；
Fig. 3 is that fiber-optic grating sensor arranges schematic cross-section；
Fig. 4 is that A groups fiber grating strain spends schematic diagram；
Fig. 5 is that B groups fiber grating strain spends schematic diagram；
Fig. 6 is that C groups fiber grating strain spends schematic diagram；
Fig. 7 is optical fiber Bragg raster structural representation；
Fig. 8 is light source incidence spectrogram；
Fig. 9 is optical fiber Bragg raster reflection characteristic figure；
Figure 10 is optical fiber Bragg raster transmissison characteristic figure；
Figure 11 is three-dimensional drilling surrouding rock stress distribution figure；
Figure 12 is the stress schematic diagram of resistance strain gage；
Figure 13 is conventional housings (epoxy resin：TypeA) rheology time-history curves；
Figure 14 is conventional housings (epoxy resin：TypeB) rheology time-history curves；
Figure 15 is the utility model housing rheological experiment result；
Figure 16 is test result of the utility model sensor in calibration experiment.
Wherein, 1, guide rod；2nd, sealing ring neck；3rd, plastic hole；4th, plunger；5th, plastic emitting passage；6th, steady pin；7th, housing
Glue storage cavity；8th, fiber grating is measured；9th, independent grating sensor；10th, null grating sensor；11st, orienting pin；12nd, optical fiber；
13rd, front end packing；14th, rear end packing；15th, housing, 16, connecting rod.
Embodiment
It is new below in conjunction with this practicality to make the purpose, technical scheme and advantage of the utility model embodiment clearer
Accompanying drawing in type embodiment, clear, complete description is carried out to the technical scheme in the embodiment of the utility model.Obviously, retouched
The embodiment stated is the utility model part rather than whole embodiments.For the ease of description, illustrate only in accompanying drawing with
The related part of utility model.
It should be noted that in the case where not conflicting, the utility model for generally describing and showing in this figure is real
Applying the component of example can be configured to arrange and design with a variety of.It is understood that specific implementation described herein
Example is used only for explaining relevant utility model, rather than the restriction to the utility model.Based on the embodiment in the utility model, sheet
The every other embodiment that field those of ordinary skill is obtained under the premise of creative work is not made, belongs to this practicality
Novel protected scope.
In description of the present utility model, it is also necessary to explanation, unless otherwise clearly defined and limited, belong to and " set
Put ", " connection " should broadly understood, for example, it may be fixedly connected or be detachably connected, or the connection of one；Can
To be mechanical connection or electrical connection；Can be directly connected to, can also be indirectly connected with by intermediary, Ke Yishi
The connection of two element internals.For the ordinary skill in the art, with concrete condition above-mentioned term can be understood at this
Concrete meaning in utility model.
Embodiment one：
Organization Charts of the Fig. 1 as the test system of Application Example of the present utility model.
As shown in figure 1, measuring system framework can include monitoring device 101,102,103,104, transmission medium and measurement
Instrument 201.Transmission medium is realizing the communication connection between monitoring device 101,102,103,104 and measuring instrument 201.
Wherein, transmission medium mainly includes optical cable.
Terminal device can be single measuring instrument or various electronic equipments, including but not limited to PC,
Smart mobile phone, intelligent television, tablet personal computer etc..
It should be understood that the number of the monitoring device, terminal device in Fig. 1 is only schematical.According to realizing needs, one
Individual terminal device can connect a limited number of monitoring device, if for example, every sensor has two communication optical fibers, 32 passages end
End setting can connect 16 sensors.
As mentioned in the background, in underground monitoring early warning bump, the monitoring and warning cycle is typically from sensing
Device is embedded to be started to terminate after exceeding the segment distance of monitoring surface one to working face, and it will typically continue more than ten days to the several months, wherein
It is important that：Sensor is had to long-time stability, can not there is obvious rheological characteristic under certain stress level.
And traditional In-situ rock stress measurement technology is due to using electric bridge acquisition mode, it is necessary to ensure stable supply in whole detection process
Electricity, therefore the shortcomings that anti-interference, durability and long-time stability etc. are poor be present, in addition, corresponding sensor substrate has
Obvious rheological characteristic, and easily influenceed and failed by the complicated underground environment such as acid and alkali corrosion, it is difficult to adapt to wanting for long-term engineering monitoring
Ask, accurately long-term remote dynamic detection can not be realized.And Disturbance stress test is still immature, it is existing at present but its only
Test single direction in coal and rock and not three-dimensional turbulence stress value, and long-term on-line monitoring in real time can not be realized.
In terms of the laboratory exploration of this area, there is the preliminary trial directly fiber grating being deployed in housing.But
Under this trial, the survival rate of fiber grating is especially low, and most fiber Bragg grating strain sensors can fail, root
Originally the industrialization production of monitoring device can not be realized.And the accuracy of long term monitoring is not just known where to begin more.
In view of the drawbacks described above of prior art, the embodiment of the present application provides a kind of can measure for a long time and disturbs crustal stress
Triaxiality monitoring device, as shown in Fig. 2 triaxiality monitoring device can include：In the housing of tube structure, the housing
For interior outer double-layer structure, the modulus of elasticity of internal layer and cladding material is 8-15GPa, tensile strength is not less than 60MPa；In housing
Between internal layer and outer layer, at least provided with the mutually different measurement fiber grating 8 of six direction, the grid of the measurement fiber grating
Section length is 2-4mm.
It is very hidden for FBG monitoring device survival rate and the influence factor of long-term accurate measurements, therefore existing skill
In art, so far without a kind of device that can preferably realize three-dimensional turbulence stress long term monitoring.It experienced substantial amounts of research
After analysis and test operation, this programme, which have found, influences FBG monitoring device survival rate and long-term measurement result accuracy
Key factor：The key factor for influenceing FBG monitoring device survival rate is the grid region length of fiber grating；Influence light
The key factor of the fine long-term measurement result accuracy of grating monitoring device is the modulus of elasticity of housing.
During experiment, when select fiber grating grid region length be 1mm when, fiber grating all failures.And work as light
When the grid region length of grating is 6mm, there is serious chirp phenomenon in the fiber grating for having 83%, causes measurement result to occur wrong
By mistake.When the grid region length of fiber grating is 2-4mm, chirp phenomenon does not occur, and the survival rate of fiber grating arrives
90%, meet the requirement of monitoring device industrialized production.
In addition, the housing of traditional monitoring device, is generally made of industrial plastic, its modulus of elasticity is 2-3GPa, and
Using single layer structure.Due in conventional research and being unaware that the material of housing can influence the accurate of long-term measurement result
Property, therefore the selection of housing is never paid attention to.
It is found by experiment that, this case material has stronger rheological characteristic, will have a strong impact on the precision of long term monitoring, nothing
Method is used for long term monitoring.When housing is used instead by double-decker made of epoxy resin, fiber grating be laid in double-layer structure it
Between, and when the modulus of elasticity of internal layer and outer layer is 8-15GPa, the rheological characteristic of housing is greatly reduced, when ensure that long term monitoring
Measurement accuracy.
It is understood that when housing uses other materials, if the material can meet modulus of elasticity, tensile strength and
The related request of Poisson's ratio, you can reach corresponding effect, within the protection domain of the application.
Traditional epoxy resin housing is can be seen that under 20MPa stress levels from Figure 13-Figure 14, it is constant in stress
In the case of, strain is continuously increased, and has stronger rheological characteristic.It can be seen from fig. 15 that the case material that the utility model uses
For the German type epoxy resin of polytec TC 451, its modulus of elasticity is 10GPa, tensile strength 60MPa, Poisson's ratio 0.19,
Under 20MPa stress levels, in the case where stress is constant, strain is almost unchanged, and it is preferably steady in a long-term to illustrate that the material has
Property.As can be seen from Figure 16, using the utility model proposes sensor be used for stress measurement when, it is same have it is preferably stable
Property, solve the technical barrier that can not realize that country rock three-dimensional turbulence stress measures for a long time.Experiment proves, when the housing of monitoring device
During using above-mentioned material, it is possible to achieve up to 3-5 long term monitoring.
In addition, it can be seen from the surrouding rock stress distribution formula that drills, surrouding rock stress shares 6 isolated components, therefore sets extremely
Few 6 strain transducers being not parallel to each other, you can ensure that equation has 6 isolated components, the stress point of required solution can be solved
Amount.
Specifically, measurement fiber grating can use optical fiber Bragg raster.Fiber-optic grating sensor passes through Bragg gratings
The movement of reflection wavelength realizes the on-line measurement to structure to sense extraneous small strain change, has essential safety, anti-electricity
Magnetic disturbance, it is waterproof and dampproof, anticorrosive, durability is long and measuring accuracy is high the features such as, and long distance of signal transmission, can carry out remote
Journey, permanent monitoring, for complex condition engineering is long-term, effective triaxiality and its distribution tests provide possibility.
Measurement fiber grating 8 is divided into three groups along same circumference and equidistantly laid, and every group of measurement fiber grating 8 is at least provided with three
It is individual, circumferentially, axially and with the direction of 45 ° of axially spaced-apart lay respectively.Using this arrangement, Computing Principle is more
It is simple clear and definite.Obtained independent equation is more than 6, passes through data processing, it is ensured that collection result more science is accurate.
Further, as shown in Fig. 2 structural representation for certain monitoring device, the front opening of its housing, rear end seal
Close, the Inner Constitution of housing is accommodating the housing glue storage cavity 7 of colloidal binder；Described in being fixed with to measure on housing
Fiber grating, optical fiber 12 are drawn in the rigid connecting rod via connection housing rear end, are respectively connected on wavelength demodulation device, wavelength
(FBG) demodulator is connected with computer by signal wire.
Sensor as the monitoring device of country rock three-dimensional turbulence stress field can use following concrete structure, in housing
The cock body structure being fixedly installed at front opening by temporary fixing piece, when monitoring device is pushed to foot of hole, housing
The drilled bottom in front end stop, continue to promote monitoring device, when the stress intensity between housing and cock body structure be more than it is interim
During the intensity of fixture, temporary fixing piece failure.In the presence of thrust, the part cock body of cock body structure is housed inside housing
Interior, the colloidal binder in glue storage cavity flows out to housing under the extruding of cock body structure along the plastic emitting passage 5 in cock body structure
Outside.The front end packing 13 to plugging colloid binding agent is respectively equipped with the rear end of the front end of cock body structure and housing with after
End seal pad 14, in the presence of front end packing and rear end packing, colloidal binder is set to be filled between hull outside and drill hole inner wall
Divide filling, and rapid condensation cure.
The utility model proposes epoxide-resin glue there is of a relatively high rigidity and tensile strength, colloidal binder just
The solidifying time is 30-45 minutes, and final setting time is 15-17 hours, modulus of elasticity 8-15GPa, and tensile strength is not less than 60MPa.
The space between housing and drilling is generally filled using cement mortar as binding material in the prior art.Due to
Binding material between housing and drilling belongs to auxiliary sexual factor, therefore this factor is not closed for a long time in the art
Note.This programme is found by experiment that：Cement mortar material can be shunk in the curing process, and the tension of cement mortar material
Intensity is typically smaller than 2MPa, and sensor easily slips with country rock during for long term monitoring, causes monitoring to fail.
This programme is proposed using epoxide-resin glue as binding agent, and the modulus of elasticity to binding agent and tensile strength progress
Limit, the long-time stability of sensor and the reliability bonded between country rock can be ensured, avoid sensor and occur with country rock
Slip and caused by monitor failure, substantially increase the probability of success of monitoring, and monitoring accuracy can be significantly improved, have aobvious
The progress of work.
It is the relevant parameter of certain specific colloidal binder below：Colloidal binder injects housing glue storage cavity, in 25-35
Spend under environment, about 30-45 minutes in presetting period, final setting time about 16 hours, tensile strength 60-90MPa, modulus of elasticity 10GPa,
Poisson's ratio 0.19, there is no rheology under 20MPa stress.
It is appreciated that when providing the demand of this colloidal binder, it can commercially buy and meet above-mentioned parameter
Colloidal binder.And the selection of colloid parameter has weight to realizing the monitoring steady in a long-term of sensor, improving monitoring accuracy
Want meaning.
Be additionally provided with the temperature-compensating grating sensor of retractable in rigid connecting rod, temperature-compensating grating with it is described
Fiber grating is same matrix material, the parameter of the temperature-compensating grating sensor and the parameter one of the grating sensor
Cause.
The specific layout scheme for measuring fiber grating 8 and temperature-compensating grating sensor 10 is as follows：
As shown in figures 3 to 6, along same circumference, equidistantly (120 °) are embedded into tri- groups of optical fiber of A, B, C to the firm tube outer surface of cylinder
Grating strain floriation, every group is made up of 4 measurement fiber gratings 8, spaced 45 °.High precision temperature compensation grating sensor 10
Parameter is consistent with measurement fiber grating 8, is arranged in inside rigid connecting rod, and wave length shift caused by rejecting thermal perturbation, making should
Become measurement is not influenceed by variation of ambient temperature.
To solve the problems, such as optical fiber grating temperature and the cross sensitivity of strain, the temperature compensation principle based on raster method makes intelligence
Energy temperature compensation structure, realize under Complex Temperature environment to being monitored while temperature and strain, greatly improve rock mass deformation or destruction
Measuring accuracy, be more beneficial for the prevention of disaster.
Strain measurement need reject thermal perturbation caused by wave length shift, make shadow of the strain measurement not by variation of ambient temperature
Ring, as the temperature compensation method of fiber grating.Using the temperature compensation act that do not stress in the application, optical fiber Bragg raster is laid
In measurand, for the deformation test of material, on another component for being laid in identical material and not stressing, temperature is only experienced
Change；Using the grating that do not stress as reference, you can obtain the logarithmic strain of material.Using high precision temperature compensation grating sensor 10
Make temperature-compensating, solve strain-Temperature cross-over tender subject, eliminate the strain measurement error as caused by thermal perturbation.
A diameter of 36mm of housing 15, typically, the drill pipe diameters of testing bore holes is mostly 37mm (drilling diameter about 38mm), shell
The diameter of body 15 is slightly less than drill pipe diameter, on the one hand can guarantee that housing 15 can be stretched in drilling, on the other hand ensures consolidation
Colloid thickness it is suitable, existing enough adhesion strengths, be unlikely to excessive using colloid again and produce waste.
Cock body structure is fixed at by temporary fixing piece at the front opening of housing 15.Temporary fixing piece is steady pin 6,
Steady pin 6 is provided with breach at the default place of fractureing, when the stress intensity between housing 15 and cock body structure is more than the intensity of steady pin 6
When, steady pin 6 is broken off in indentation, there, plunger 4 is pushed into housing 15.This structure design is simple, easy to use, and cost is low
It is honest and clean.
Dismountable guide rod 1 can be provided with the front end of cock body structure, the end of guide rod 1 has forwards convex
Go out body, can be the guiding arrow in cone in the present embodiment, to facilitate propulsion of the monitoring device into drilling.It is easy to grasp
Bottom hole position, it is ensured that the stabilization of follow-up plastic squeeze process thrust.
Rear end packing 14 and front end packing 13 are Gask-O-Seal, the outside dimension of Gask-O-Seal and the size to drill
Match, connecting rod 16 is provided with sealing ring neck 2, and rear end packing 14 is fixed in connecting rod 16 by sealing ring neck 2.
In the present embodiment, in order to improve the sealing characteristics to colloidal binder, front end packing and rear end packing are by three layers
The rubber seal for being spaced setpoint distance is formed.It should be understood that form the number of the rubber seal of front end packing and rear end packing
Mesh is only schematical, according to needs are realized, can have one or the rubber seal of other numbers.Sealing ring lower potion is set
A circle plastic hole 3 is put, it is connected with internal plastic emitting passage 5.
The rear end of housing glue storage cavity is provided with an independent grating sensor 9, when cock body structure reaches housing glue storage cavity bottom,
Independent grating sensor 9 can be squeezed off, and the channel transmission data accordingly lacks, and infer that colloidal binder is all extruded with this, with
Hole wall bonds.
Connecting rod 16 is provided with orienting pin 11, and orienting pin 11 is rabbeted with push rod locating slot, avoids testing during push
Device rotates, and ensures the relatively stable of sensor installation position.
The embodiment of the present application additionally provides a kind of triaxiality monitoring system that can measure disturbance crustal stress for a long time, the prison
Examining system includes the monitoring device of above-mentioned country rock three-dimensional turbulence stress field, additionally including terminal device, wavelength demodulation device and
Direction finder, the fiber grating are connected by the wavelength demodulation device with the terminal device, the direction finder and the terminal
Equipment connects；
The terminal device obtains the fiber grating by the wavelength signals of the fiber grating and corresponds to answering at measuring point
Become data, the terminal device obtains the azimuth information of the fiber grating according to the direction finder；
The terminal device is according to the modulus of elasticity and Poisson's ratio of the fiber grating preservation body and the fiber grating
Azimuth information, the strain data is converted to the Disturbance stress data of country rock, and then obtain the stress state at measuring point.
The preservation body refers to the structure of fiber grating environmental effect, including housing and colloidal binder, and drilling
Country rock at hole wall.
Further, the temperature-compensating grating sensor that can freely stretch vertically, the temperature are additionally provided with monitoring device
It is consistent with the parameter of the grating sensor to spend the parameter of null grating sensor, the terminal device and the temperature-compensating light
Gate sensor is connected, and terminal device can be made directly to calculate the accurate triaxiality value eliminated after temperature influences.
Traditional method for measuring stress, it is that the strain that will be measured determines country rock with reference to the modulus of elasticity and Poisson's ratio of country rock
Stress variation situation.Problems be present in this：What is actually measured is the strain value of foil gauge carrier, although foil gauge carrier
Preservation has difference in country rock between the real strain value of strain value and country rock of foil gauge carrier, i.e.,：Measured should
Variate is not the real strain value of country rock, can not be obtained with the modulus of elasticity and Poisson's ratio of this strain value combination country rock itself
The situation of change of real surrouding rock stress.
In the present embodiment, strain transducer is fixed on housing, is brought into close contact between housing and country rock by consolidating colloid.
When country rock deforms, colloid can be extruded and the corresponding housing provided with strain transducer also deforms, due to housing
Modulus of elasticity is less than country rock, and the deformation of country rock is equal to the deformation of housing, and causes the deformation that housing occurs to be examined equal to sensor
The deformation measured.Using the strain transducer being arranged on housing, the strain value of housing or country rock is obtained, according to housing, consolidation
The modulus of elasticity and Poisson's ratio of colloid and country rock, the Disturbance stress value of country rock can be calculated.This cleverly thinking separately wards off footpath
Footpath, by indirectly measuring the strain value of housing, to measure the stress value of country rock, simple in construction, cost is cheap, easy for construction,
It is hardly damaged, test result is more accurate.
The technical scheme provided according to present application example, by being improved to case material, there is housing preferable
Long-time stability；By setting fiber Bragg grating strain sensor in housing, make the corrosion resistance of test device, anti-underground water and
The performance of electromagnetic interference greatly improves, and is not influenceed by signal strength and decay, for rock mass engineering project complicated geological and the hydrology
The strong adaptability of condition, the rock mass stress test to construction phase of project is not only realized, more can apply to long-term in engineering operation
Tracking and monitoring, stability is good, and reliability is high.The technology is in first place in the world, fills up blank in the industry.
The three-dimensional stress constraint and Disturbance stress spatial distribution in rock mass are truly reflected using the pre-buried technology of stress test
And its evolutionary process, it is engineering for complex condition engineering is long-term, effective triaxiality and its distribution tests provide possibility
The early warning and control of disaster provide basic data in situ.
As can be seen here, the technical scheme that the application provides can realize that bump three-dimensional should under underground space complex environment
The dynamic long term monitoring of power evolutionary process, so as to solve the problems, such as that the dynamic monitoring of bump triaxiality can not be realized in the past.
Stress based on optical fiber grating sensing and the long-term dynamics triaxiality monitoring device of hole wall strain measurement technique is surveyed
It is as follows to try principle：
(1) optical fiber Bragg raster structure and sensing principle
When the light wave in optical fiber is by Bragg gratings, meets that the light of Bragg grating wavelength conditions is reflected back and form
For reflected light, remaining light turns into transmitted light.The change of extraneous parameter will cause the drift of reflected light wavelength, and by wavelength
The detection of drift value can obtain the variable quantity of extraneous parameter, here it is the general principle of optical fibre Bragg grating sensing, as Fig. 7-
Shown in Figure 10.Optical fibre Bragg grating sensing meets Maxwell's Classical Equation, in conjunction with the fiber coupling theory of modules, utilizes optical fiber
The orthogonality relation of grating transmission mode, take into full account the perturbation relation of fiber grating refractive index, you can push away and demonstrate,prove out fiber grating
Transmission theory.
According to coupled mode theory, the central wavelength lambda of reflected light signalBWith grating period A and the effective refractive index of fibre core
neffRelevant, the fundamental formular for obtaining optical fiber Bragg raster reflection wavelength is：
λB=2neffΛ (1)
Fiber grating is a kind of optical element simultaneously sensitive to strain and temperature, and temperature control is strain sensitivity
10 times or so.So when the extraneous measured middle cardiac wave for causing optical fiber grating temperature, stress changes all to cause reflected light
Length changes.The centre wavelength of fiber grating and temperature, the relation of strain are
In formula, PeFor the ga(u)ge factor of fiber grating；ξ is thermal refractive index coefficient；α is linear thermal expansion system
Number；Kε1For the coefficient of strain；KT1For temperature control coefficient.
When being tested using fiber grating, it is necessary to consider strain-Temperature cross-over tender subject of fiber grating.Strain
Wave length shift caused by needing rejecting thermal perturbation is measured, strain measurement is not influenceed by variation of ambient temperature, as optical fiber
The temperature compensation method of grating.Frequently with the temperature compensation act that do not stress in practical application, by an optical fiber Bragg raster be laid in by
Object is surveyed, for the deformation test of material, on another component for being laid in identical material and not stressing, only experiences temperature change
Change；Using the grating that do not stress as reference, you can obtain the logarithmic strain of material.
Assuming that the initial wavelength of null grating is λB2, temperature control coefficient is KT2, optical fiber grating temperature and wavelength it is complete
Whole expression formula is：
In formula, kwg2Represent wave length shift coefficient caused by waveguiding effect.
Due to thermal linear expansion coefficient two orders of magnitude small compared with thermal refractive index coefficient, waveguiding effect is to temperature in addition
The influence of sensitivity coefficient is extremely faint, small compared with elasto-optical effect, therefore can when analyzing Temperature Sensitivity Coefficient of Fiber Bragg Gratings
The refractive index temperature system of material is substantially dependent on to ignore influence, temperature control coefficient caused by waveguiding effect completely
Number.Therefore, above formula can abbreviation be：
Simultaneous formula (2), (4), make γ=KT1/KT2：
Δ ε=(Δ λB1/λB1-γΔλB2/λB2)/Kε1 (5)
It is same matrix material from fiber grating, then the TEMP coefficient of grating is consistent, γ=KT1/KT2=1,
Above formula is changed into：
Δ ε=(Δ λB1/λB1-ΔλB2/λB2)/Kε1 (6)
Based on above-mentioned analysis, you can try to achieve strain variation by the wavelength change and sensing characteristicses of fiber grating.
(2) stress resolution principle
A, drill surrouding rock stress distribution formula
Elastic theory gives drilling surrouding rock stress distribution formula, is utilized on the basis of the strain of measuring point boring surface is obtained
The formula can obtain surrouding rock stress state at this.Initial rock stress field is a 3-D stree field, its six components of stress (σx、σy、
σz、τxy、τyz、τzx) distribution reference picture 11.
The drilling surrouding rock stress distribution formula that elastic theory provides is as follows：
In formula, a represents boring radius, σrFor radial stress under polar coordinate system, σθFor circumference stress under polar coordinate system, σ 'zFor
Axial stress under polar coordinate system, τrθFor the shear stress under polar coordinate system in r- θ planes, τθzFor under polar coordinate system in θ-Z plane
Shear stress, τrzFor the shear stress under polar coordinate system in r-Z planes.
It should be noted that the coordinate system for calculating the stress of primary rock is different from the coordinate system of hole skirt rock stress state,
The former is rectangular coordinate system, and the latter is cylindrical coordinate, but both both i.e. z-axis that also have something in common are consistent.In addition, in cylindrical coordinates
In system, the positive direction at θ angles takes the rotate counterclockwise direction of x-axis.σ ' in formula (9)z、σzMeaning is different, and the former is hole skirt rock
The stress z-axis components of stress and the latter is stress of primary rock component, only as boring radius r → ∞, just to have the two equal.
B, the strain of grating stressometer and country rock triaxiality component relational expression
According to the stress figure (as shown in figure 12) of each grating strain floriation, show that strain rosette surveys strain value and hole wall
Relation between the components of stress：
In formula, εθ,εz,ε±45It is that hole wall is circumferential, axially and the strain value with drilling axis into ± 45 ° of directions respectively, γθz
It is shear strain value.
Utilize the hole wall components of stress (σθ、σ′z、τθz) and surrouding rock stress component (σ at thisx、σy、σz、τxy、τyz、τzx) between
Relational expression (7)~(12), can obtain following equations：
From the construction of grating stressometer, 3 groups of strain rosettes of three groups of equidistantly distributeds can obtain 12 equations.Country rock
Stress shares 6 isolated components, and in 12 resulting equations at least 6 be independent, therefore the components of stress be can be with
Solve.
Unlike hole wall stressometer：In order to ensure bonding quality, the cylinder of grating stressometer is by two layers of asphalt mixtures modified by epoxy resin
Fat, which pours, to be formed, and grating sensor is placed between the two, is not directly pasted as hole wall stressometer on hole wall, thus is surveyed
Obtaining strain value and hole wall stressometer measured result has certain difference.Introduce by physical-mechanical properties of rock, stressometer itself and
Adjusted coefficient K (the K that the factors such as boring radius influence1、K2、K3、K4), obtain revised calculation formula specifically as formula (20)-
(26) shown in：
x1=3-4 υ1；x2=3-4 υ2；
D=(1+x2n)[x1+n+(1-n)(3m2-6m4+4m6)]+(x1-x2n)m2[(1-n)m6+(x1+n)]
In formula, εθThe circumferential strain measured for grating stressometer, εzFor axial strain, γθzIt is shear strain value；a0、G1And
v1It is then the inside radius of stressometer, the modulus of shearing of cylinder material and Poisson's ratio respectively；a1It is installation aperture radius；G, v then distinguishes
For the modulus of shearing and Poisson's ratio of rock；ρ is the radial distance of strain rosette present position in three-dimensional test device.
Adjusted coefficient K is related to stressometer elasticity modulus of materials, Poisson's ratio, geometry, boring radius etc., not pervasive
Constant.For everywhere stressometer installation site, adjusted coefficient K value at this must be all calculated.
This is the stress resolution principle of optical fibre grating three-dimensional test device, passes through detecting to grating wavelength drift value
To the strain of boring surface, accurate dynamic 3 D stress is calculated based on hole wall stress measurement technology.
The specific embodiment that Disturbance stress dynamic long term monitoring is carried out using triaxiality test device is as follows.
Step 1：Detecting earth stress is carried out, embodiment is：
SGM -1A type geological drilling rigs are used in selected test position, with φ 42mm extension drill rods, with special set of coring
Cylinder and drill bit (φ 130mm), creep into instrument connection, to 3-5 times of depths of tunnel span, to ensure to strain in surveyed wall
Meter installation site is located at initial stress area.The updip that drills is more than 5 °, so that draining and cleaning drill.
Step 2：Bottom hole is polished with flat drill head, and horn mouth is got with taper bit, is then beaten from bottom hole a diameter of
38mm concentric aperture, small hole depth 50cm；After aperture is accomplished fluently, rinsed well with water, then cleaned with alcohol or acetone.
Step 3：The reliability and stability of monitoring device are checked, optical fiber leading-out terminal is connected with (FBG) demodulator, passes through calculating
Machine software adjusts operational factor；
Step 4：Optical fibre grating three-dimensional test device is installed：Extemporaneous preparation solidifies colloidal binder, is injected into stressometer
Inner chamber, fix plunger, with the mounting rod with finder by three-dimensional test device be sent into hole in precalculated position, infer fix
Pin, binding agent is extruded into the gap between stressometer and aperture from stressometer inner chamber, after binding agent solidification, is write down
The drift angle of stressometer and the orientation of drilling and inclination angle.
Step 5：After cementing agent solidification, you can carry out covering core experiment.Often extract 3cm cores and carry out an instrument readings,
(being about that drill bit exceedes stressometer center 45° angle) stops set core when reading does not change with drilling depth.After set core terminates, band is taken out
There is the core of stressometer.
Step 6：Core is tested：After set core takes out, the modulus of elasticity of rock and the determination test of Poisson's ratio are carried out immediately.
Then according to the wavelength change of test gratings sensor, dynamic strain data are obtained based on fiber grating sensing technology principle；Enter
And three-dimensional ground stress size and Orientation is calculated by hole wall stress measurement technology.
Above-mentioned steps can be obtaining the stress of primary rock of country rock.It is understood that other can also be used traditional
Method obtains the stress of primary rock.
After obtaining the stress of primary rock, carry out Disturbance stress in work progress and monitor, embodiment is：
Repeat step 1- steps 4, it is not required to cover coring；
According to the wavelength change of test gratings sensor, based on fiber grating sensing technology principle and hole wall stress measurement skill
Art calculates triaxiality changing value；Then it is added with protolith crustal stress value and obtains dynamic 3 D stress state parameter.
Embodiment two：
The present embodiment is distinguished as with embodiment one：
Housing uses German polytec TC451 (modified) epoxide resin material, modulus of elasticity 8GPa, tensile strength
For 90MPa, continuing to monitor the time can reach more than three months.
Embodiment three：
The present embodiment is distinguished as with embodiment one：
Housing uses German polytec TC 417 (modified) epoxide resin material, modulus of elasticity 15GPa, and tension is strong
Spend for 80MPa, continuing to monitor the time can reach more than three months.
Above description is only the preferred embodiment of the application and the explanation to institute's application technology principle.People in the art
Member should be appreciated that utility model scope involved in the application, however it is not limited to what the particular combination of above-mentioned technical characteristic formed
Technical scheme, while should also cover in the case where not departing from utility model design, by above-mentioned technical characteristic or its be equal
Other technical schemes that feature is combined and formed.Such as features described above has with (but not limited to) disclosed herein
The technical scheme that the technical characteristic for having similar functions is replaced mutually and formed.
Claims (10)
- A kind of 1. monitoring device of country rock three-dimensional turbulence stress field, it is characterised in that including：Housing, in tube structure, the housing is interior outer double-layer structure, the modulus of elasticity of internal layer and cladding material is 8-15GPa, Tensile strength is not less than 60MPa；The mutually different fiber grating at least six directions, it is laid between the internal layer of the housing and outer layer, the optical fiber The grid region length of grating is 2-4mm.
- A kind of 2. monitoring device of country rock three-dimensional turbulence stress field according to claim 1, it is characterised in that：The optical fiber Grating is bend insensitive optical fiber Bragg gratings, and the case material uses lucite.
- A kind of 3. monitoring device of country rock three-dimensional turbulence stress field according to claim 1, it is characterised in that：The optical fiber Grating is divided into three groups along same circumference and equidistantly laid, grating sensor described in every group at least provided with three, respectively circumferentially, axle To and with 45 ° of axially spaced-apart direction lay.
- 4. according to a kind of monitoring device of any described country rock three-dimensional turbulence stress fields of claim 1-3, it is characterised in that：Prison Survey on device and be additionally provided with the temperature-compensating grating of retractable, the temperature-compensating grating is same with the fiber grating Matrix material.
- A kind of 5. monitoring device of country rock three-dimensional turbulence stress field according to claim 1, it is characterised in that：The housing Inside have to accommodate the housing glue storage cavity of colloidal binder, the colloidal binder to realize the hull outside with The bonding of borehole wall.
- A kind of 6. monitoring device of country rock three-dimensional turbulence stress field according to claim 5, it is characterised in that：The colloid The presetting period of binding agent is 30-45 minutes, and final setting time is 15-17 hours, and modulus of elasticity 9-12GPa, tensile strength is not Less than 60MPa.
- A kind of 7. monitoring device of country rock three-dimensional turbulence stress field according to claim 5 or 6, it is characterised in that：Institute To state and cock body structure is provided with the front opening of housing, the cock body structure is fixedly connected by temporary fixing piece with the housing, It is described interim fixed when the stress intensity between the housing and the cock body structure is more than the intensity of the temporary fixing piece Part is failed, and at least part cock body of the cock body structure can be housed inside in the housing, the cock body structure and the housing Between have the colloidal binder can be extruded to the plastic emitting passage between the outside of the housing and hole wall.
- A kind of 8. monitoring device of country rock three-dimensional turbulence stress field according to claim 1, it is characterised in that：The housing The rear end of glue storage cavity is provided with an independent grating sensor, when cock body reaches housing glue storage cavity bottom, the independent grating sensor Squeeze off, corresponding channel transmission data missing.
- 9. according to a kind of monitoring system of any described country rock three-dimensional turbulence stress fields of claim 1-8, it is characterised in that：Also Including terminal device, wavelength demodulation device and direction finder, the fiber grating passes through the wavelength demodulation device and the terminal device Connection, the direction finder are connected with the terminal device；The terminal device obtains the fiber grating by the wavelength signals of the fiber grating and corresponds to dependent variable at measuring point According to the terminal device obtains the azimuth information of the fiber grating according to the direction finder；Modulus of elasticity and the side of Poisson's ratio and the fiber grating of the terminal device according to the fiber grating preservation body Position information, the strain data is converted to the Disturbance stress data of country rock, and then obtain the stress state at measuring point.
- A kind of 10. monitoring system of country rock three-dimensional turbulence stress field according to claim 9, it is characterised in that：The prison Survey on device and be additionally provided with the temperature-compensating grating sensor of retractable, the parameter of the temperature-compensating grating sensor and institute It is consistent to state the parameter of grating sensor, the terminal device is connected with the temperature-compensating grating sensor.
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| CN108918012A (en) * | 2018-07-16 | 2018-11-30 | 中铁十四局集团有限公司 | One kind being used for Shield-bored tunnels country rock Disturbance stress monitoring method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108918012A (en) * | 2018-07-16 | 2018-11-30 | 中铁十四局集团有限公司 | One kind being used for Shield-bored tunnels country rock Disturbance stress monitoring method |
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| CN109655007A (en) * | 2018-12-07 | 2019-04-19 | 贵州桥梁建设集团有限责任公司 | A kind of interior pipe inner concrete deformation monitoring method being perfused of grand bridge tubular arch |
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| CN109779623A (en) * | 2019-02-25 | 2019-05-21 | 中国标准化研究院 | A kind of mine cylinder monitoring method |
| CN113447173A (en) * | 2021-05-17 | 2021-09-28 | 东北石油大学 | Method for directly measuring stress of coiled tubing with arc defects in photoelastic experiment |
| CN113447173B (en) * | 2021-05-17 | 2022-08-30 | 东北石油大学 | Method for directly measuring stress of coiled tubing with arc defects in photoelastic experiment |
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