Background technology
Underground both at home and abroad or stable to surrounding rock of chamber and side slope on the ground, the anchor rod anchored country rock of stable employing, especially the colliery underground mining of tunnels, tunnel, side slope need be dug a large amount of tunnels in the down-hole in a large number.According to incompletely statistics, the tunnel total length of the annual new driving in state-owned big-and-middle-sized colliery up to 8000km about, be the tunnel of digging in the coal seam more than 80%, keep the tunnel unimpeded significant to construction of coal mine with safety in production with adjoining rock stability.Simultaneously; The tunnel of excavation such as metallurgical mine, water conservancy, railway, highway, national defence; Basically all adopting bolt supporting, is to safeguard a kind of active support mode the most frequently used in the stability of the roadway, and roadway surrounding rock intensity is had invigoration effect; Can significantly improve the stability of country rock, have advantages such as support cost is low, one-tenth lane speed is fast, good in economic efficiency in addition.
The anchoring quality of anchor pole is directly connected to the stable of surrounding rock of chamber and side slope, must detect the anchoring quality of anchor pole, control.The quality of anchor rod anchored quality is not only relevant with the anti-group power of the integral body of anchor pole, but also relevant with the anchor force of each section.Only determine the anchor force of each section, could make correct evaluation the anchoring quality of anchor pole.Simultaneously, the multidate information method of bolt supporting modern concepts, also requirement can promptly be given the staff with the information feedback after the bolt supporting, so that the staff can adjust timely, instructs supporting backward.
Traditional detection means is many, mainly contains several types of sensors such as strain ga(u)ge formula, differential resistance strain gage, steel chord type and flat jack formula, the method and the GPR that have the scholar to adopt the audio frequency stress wave to detect simultaneously both at home and abroad, methods such as wavelet analysis.These electrical category sensitive components use in a large number, and the long-time stability of existing proven technique, especially strain ga(u)ge, temperature drift, zero point stability and long Distance Transmission problem are solved preferably.But these sensors still exist protection against the tide, waterproof, interference free performance poor; Can not realize shortcomings such as distributed measurement; Simultaneously; Also have the real-time detection needs can not finely satisfy engineering, have in addition long, equipment of whole testing process cycle install extremely loaded down with trivial details, the defective that can't carry out permanently effective detection to whole process.
Summary of the invention
The object of the present invention is to provide a kind of simple in structure, easy for installation, detection speed is fast; Remote monitor; Reuse, be easy to protection and maintenance; Can detect in real time anchor pole is stressed, and can realize a kind of fiber grating detection system device that detects anchor-holding force of anchor bolt of distributed measurement.
Another object of the present invention is to provide detection method.
In order to overcome the deficiency of prior art; Technical scheme of the present invention is to solve like this: a kind of fiber grating detection system device that detects anchor-holding force of anchor bolt comprises nut, anchor ergometer, optical fiber grating anchor ergometer, bearing plate, first fiber-optic grating sensor, cylindrical shell, second fiber-optic grating sensor, anchor pole, the 3rd fiber-optic grating sensor, electric wire strain gauge, machine calculation machine, fiber Bragg grating (FBG) demodulator, elastic body, fiber pigtail, first fiber grating, second fiber grating; Special character of the present invention is that said anchor pole one end connects a nut, an axis force of anchor machine, an optical fiber grating anchor ergometer successively respectively; Said optical fiber grating anchor ergometer is connected with bearing plate; The said anchor pole other end passes bearing plate and is connected with cylindrical shell; Said cylinder lumen successively respectively with first fiber-optic grating sensor, second fiber-optic grating sensor; The 3rd fiber-optic grating sensor connects; Said optical fiber grating anchor ergometer, fiber-optic grating sensor one end are connected with fiber Bragg grating (FBG) demodulator through fiber pigtail; Said fiber Bragg grating (FBG) demodulator is connected with machine calculation machine, and said machine is calculated machine and is connected with electric wire strain gauge, and the said electric wire strain gauge other end is connected with the fiber-optic grating sensor other end through fiber pigtail; Be connected with elastic body and fiber pigtail on said fiber-optic grating sensor one end face, the fiber-optic grating sensor inner chamber is provided with first fiber grating and second fiber grating.
Said cylinder lumen is equipped with at least 3 fiber-optic grating sensors at interval.
Said optical light sensor is that fiber-optic grating sensor is connected in series successively and constitutes 1 linear array, constitutes three arrays after its every linear array is connected in parallel at least.
4 ,-and kind of described detection system Device Testing method, undertaken by following step:
(1), the built-in wideband light source of fiber Bragg grating (FBG) demodulator applies light source through optical cable and gives the 3rd fiber-optic grating sensor and optical fiber grating anchor ergometer; The wavelength value that the optical signals fiber Bragg grating (FBG) demodulator dress that the 3rd fiber-optic grating sensor and optical fiber grating anchor ergometer return changes sensor into inputs to computing machine; Through calculating wavelength shift, wavelength value is converted to the stress value of anchor pole end;
(2), accurate first fiber-optic grating sensor that distributes, second fiber-optic grating sensor, the 3rd fiber-optic grating sensor are through different fiber grating reflection optical wavelength
,
,
; Corresponding with anchor cable, anchor pole along each measurement point; Experience respectively the distribute stress of measuring point of anchor cable, anchor pole respectively along the line; Its catoptrical wavelength is changed; The reflected light that changes spreads out of from measure field through Transmission Fibers; Survey the size of its wavelength by fiber Bragg grating (FBG) demodulator; Through calculating wavelength shift, wavelength value is converted to strain size and the anchor cable of each measuring point of rock bolt shank, the stress distribution of anchor pole;
(3), fiber grating is a kind of optical device responsive simultaneously to temperature and strain, and the sensitivity of temperature is about 10 times of strain sensitivity, when using fiber grating sensing system to detect; Taken into full account the temperature cross sensitivity of fiber grating; Promptly fiber grating sensing system has been carried out temperature compensation, eliminating temperature influences strain, improves the precision of measuring; The temperature compensation that employing does not stress carries out temperature compensation to the fiber grating experimental system; Temperature compensation is that a fiber grating is laid on the anchor ergometer, another root be laid in anchor rod force-measuring and the member that do not stress on, only experience variation of temperature; Fiber-optic grating sensor not stress is reference, has obtained the logarithmic strain value of anchor pole.
The present invention compared with prior art; Have simple in structure, volume is little, corrosion-resistant, anti-electromagnetic-radiation, light path is flexible, easy for installation, detection speed is fast; Protection and maintenance are reused, are easy to remote monitor, is convenient to realize remote measurement; Can detect in real time anchor pole is stressed, and can realize the characteristics of distributed measurement; Because fiber-optical grating temperature sensor adopts the Wavelength-encoding technology, eliminated the influence of light source power fluctuation and system loss, be applicable to long term monitoring; Individual fiber grating is together in series, and forms quasi-distributed temperature measurement system, uses the optical cable connection line, can realize remote monitoring; Simultaneously, also have measuring accuracy high, steady signal transmission, the advantage that long-time stability are good.This pick-up unit can effectively carry out the anchor pole quality testing, for the security maintenance of realizing tunnel, tunnel, side slope provides the science guarantee.Be widely used in the tunnel and the side slope of excavations such as colliery, metallurgical mine, water conservancy, railway, highway, national defence.
Embodiment
Accompanying drawing is embodiments of the invention.
Below in conjunction with accompanying drawing and embodiment summary of the invention is described further: with reference to Fig. 1, shown in Figure 2; A kind of fiber grating detection system device that detects anchor-holding force of anchor bolt comprises nut, anchor ergometer, optical fiber grating anchor ergometer, bearing plate, first fiber-optic grating sensor, cylindrical shell, second fiber-optic grating sensor, anchor pole, the 3rd fiber-optic grating sensor, electric wire strain gauge, machine calculation machine, fiber Bragg grating (FBG) demodulator, elastic body, fiber pigtail, first fiber grating, second fiber grating; Said anchor pole 8 one ends connect a nut 1, axis force of anchor machine 2, an optical fiber grating anchor ergometer 3 successively respectively; Said optical fiber grating anchor ergometer 3 is connected with bearing plate 4; Said anchor pole 8 other ends pass bearing plate 4 and are connected with cylindrical shell 5; Said cylindrical shell 5 inner chambers successively respectively with first fiber-optic grating sensor 6, second fiber-optic grating sensor 7; The 3rd fiber-optic grating sensor 9; Connect, said optical fiber grating anchor ergometer 3, fiber-optic grating sensor one end are connected with fiber Bragg grating (FBG) demodulator 12 through fiber pigtail 14, and said fiber Bragg grating (FBG) demodulator 12 is connected with machine calculation machine 11; Be connected with elastic body 13 and fiber pigtail 14 on said fiber-optic grating sensor one end face, the fiber-optic grating sensor inner chamber is provided with first fiber grating 15 and second fiber grating 16.
Said cylindrical shell 5 inner chambers are equipped with at least 3 fiber-optic grating sensors at interval.
Said optical light sensor is that fiber-optic grating sensor is connected in series successively and constitutes 1 linear array, constitutes three arrays after its every linear array is connected in parallel at least.
Shown in Figure 3, inner two measuring points of optical fiber grating anchor ergometer are with the plus load change curve.
Can know that by figure the wavelength variable quantity of FBG1 is greater than FBG2, in axial 12 loading procedures, the maximum wavelength drift value of two fiber gratings is respectively 1.09nm and 0.915nm.The mean wavelength drift value FBG1 of adjacent twice loading is that 0.091nm, FBG2 are 0.076nm, loads back two rate of curve for the second time and diminishes, and the wavelength shift of FBG1 is 0.058nm, and the wavelength shift of FBG2 is 0.05nm.
Shown in Figure 4, shaft fiber grating strain amount is with the anchorage length change curve,
Can know by figure; Rock bolt shank fiber grating strain change curve can be found out under the different loads; The curve population distribution is more even; When being loaded on 6.53kN for the first time; The dependent variable of the FBG1 of first measuring point place is maximum; The strain variation amount reach 216
; Along with the increase gradually of plus load, the strain variation amount progressively reduces, load at every turn strain variation increase about 109.58
; The maximum strain variable quantity amount of FBG2 be 156
, the average each strain value that loads increase by 104.75
; The maximum strain variable quantity amount of FBG2 be 46
, the average each strain value that loads increase by 3.83
.
Shown in Figure 5, three measuring points are with the external applied load change curve on the grating anchor rod body of rod, and the strain variation amount that reflects anchor rod body FBG1, FBG2, FBG3 under the different load gets development trend.
Shown in Figure 6, the data variation figure of the bolt shaft power that account temperature influence back optical fiber grating anchor ergometer is measured.
Can know that by figure an axle force data that carries out the optical fibre optical fibre grating anchor ergometer after the temperature compensation approaches the real load value more.Load for the first time wherein that anchor ergometer axle power is 6.36kN before one temperature compensation of 6.53kN measuring point, carry out that bolt shaft power is 6.51kN after the temperature compensation.It is thus clear that the method to adopting fiber grating is accurately measured bolt shaft power, it is necessary that fiber grating is carried out temperature compensation.
-kind of described detection system Device Testing method, undertaken by following step:
(1), fiber Bragg grating (FBG) demodulator 12 built-in wideband light sources apply light source through optical cable 14 and give the 3rd fiber-optic grating sensor 9 and optical fiber grating anchor ergometer 3; The wavelength value that optical signals fiber Bragg grating (FBG) demodulator 12 dresses that the 3rd fiber-optic grating sensor 9 and optical fiber grating anchor ergometer 3 return change sensor into inputs to computing machine 11; Through calculating wavelength shift, wavelength value is converted to the stress value of anchor pole end;
(2), accurate first fiber-
optic grating sensor 6 that distributes, second fiber-
optic grating sensor 7, the 3rd fiber-optic grating sensor 9 are through different fiber grating reflection optical wavelength
,
,
; Corresponding with anchor cable, anchor pole along each measurement point; Experience respectively the distribute stress of measuring point of anchor cable, anchor pole respectively along the line; Its catoptrical wavelength is changed; The reflected light that changes spreads out of from measure field through Transmission Fibers; Survey the size of its wavelength by fiber Bragg grating (FBG) demodulator; Through calculating wavelength shift, wavelength value is converted to strain size and the anchor cable of each measuring point of rock bolt shank, the stress distribution of anchor pole;
(3), fiber grating is a kind of optical device responsive simultaneously to temperature and strain, and the sensitivity of temperature is about 10 times of strain sensitivity, when using fiber grating sensing system to detect; Taken into full account the temperature cross sensitivity of fiber grating; Promptly fiber grating sensing system has been carried out temperature compensation, eliminating temperature influences strain, improves the precision of measuring; The temperature compensation that employing does not stress carries out temperature compensation to the fiber grating experimental system; Temperature compensation is that a fiber grating is laid on the anchor ergometer, another root be laid in anchor rod force-measuring and the member that do not stress on, only experience variation of temperature; Fiber-optic grating sensor not stress is reference, has obtained the logarithmic strain value of anchor pole.
According to the stressed characteristics of drawing anchor rod body, bolt shaft power is maximum in the anchoring port, reduce rapidly then, and axle power is almost 0 in the anchoring section bottom.The layout of body of rod fiber grating of the present invention as far as possible near anchor rod anchored termination portion, effectively reflects body of rod strain variation trend, embodies the stressed variation of anchor rod body.
The present invention adopts specialty optical fiber grating termination formula anchor ergometer, and is as shown in Figure 2, the detection that can be used for measuring anchor pole, anchor cable, rockbolt, crab-bolt, bridge and other load.Anchor ergometer this as high-intensity alloy cylinder, built-in 1~3 the high-precision fiber-optic grating sensor of cylindrical shell.Instrument can be measured the total load (TL) that acts on the anchor ergometer, reads each sensor respectively and can also measure inhomogeneous load or eccentric load.Being built-in with temperature sensor can the testing environment temperature and temperature compensation is provided.Instrument has high sensitivity and remarkable water resistance, and by an armouring optical cable output signal, transmission range can reach 30km farthest.This type of fiber grating dynamometer has following characteristics: what fiber grating transmitted is full light signal, and signal to noise ratio (S/N ratio) is high, and long-time stability are good.
Embodiment 1
After grating anchor rod pick-up unit and anchor pole connected, anchor rod anchored process is detected.Through fiber Bragg grating (FBG) demodulator software, data acquiring frequency is set at 2Hz, promptly gather two groups of fiber grating sensor wavelength data p.s., get the each fiber grating transient wave long value that writes down when finishing of its mean value conduct.
Adopt the online detection anchor pole of method of optical fiber grating sensing stressed at certain coal mine roadway, be suitable for the anchor pole drawbench anchor pole is carried out pull-out test.At first, 3 FBG sensors are installed on anchor pole.Optical fiber grating anchor ergometer is installed in end at anchor pole, is used to detect bolt shaft power; This anchor pole test specimen is put into the steel pipe for preparing with similar material carry out anchoring, treat that anchoring fully is being in free-ended anchor head skyhook puller system in the back, and carry out pull-out test, gradient loads and writes down corresponding FBG wavelength change.Set up the relation of sensor wavelength variation and anchor pole strain increment through the data that detect; Analyze the strain sensing characteristic of FBG sensor; Testing result with optical fiber grating anchor ergometer compares simultaneously; Optical fiber grating anchor ergometer Application feasibility in bolt shaft power detects in checking end is for practical applications provides reference.
Anchor rod anchored length is 1100mm, and injecting cement mortar proportion number is 564, at the external end head of anchor pole optical fiber grating anchor ergometer has been installed.Anchor pole adopts the mode that applies pulling capacity repeatedly to load, and the maximum load that applies for the first time is controlled within system's maximum anchorage power scope, increases load then for the second time, for the third time gradually, breaks away from up to anchor pole and grouting body.
The way that drawing takes constant gradient load to load is repeatedly carried out, and loses efficacy the whole process from beginning to be loaded into anchoring, divides 12 grades of loadings.At first begin to load,, increase 6.53kN at every turn, load altogether 9 times to 58.8kN from 0kN; From 58.8kN to 76.44kN, load 5.88kN at every turn, load altogether 3 times.By the time read the change value of centre wavelength after distortion is stable.When being loaded into 74.66kN, unload.Because the axis force of anchor meter that adopts is manually unloading, tonsure unloading such as manually uncontrollable at all during 58.8kN, therefore experiment is not done unloading and is circulated.By the time after grating centre wavelength was stablized, beginning repeated to load for the second time.When being loaded into 74.66kN, be unloaded to 0kN again.By the time after Wavelength stabilized, the destruction of carrying out for the third time loads.After axis force of anchor meter and anchor pole connected, begin anchor pole is pressurizeed.In the process of pressurization since anchor pole and sand-cement slurry contact position can't observe.Through careful observation has been carried out in the end, when pulling capacity hour, the anchoring end does not change, and after pulling capacity acquired a certain degree, the end screw began outside small distance and moves.At this moment, axis force of anchor meter reading can continue to increase, and is not going up until the tautness meter reading, explains that anchor pole will be pulled out this moment.
Shown in Figure 7, inner two measuring points of optical fiber grating anchor ergometer are with the plus load change curve.
Can know that by figure the wavelength variable quantity of FBG1 is greater than FBG2, in axial 12 loading procedures, the maximum wavelength drift value of two fiber gratings is respectively 1.09nm and 0.915nm.The mean wavelength drift value FBG1 of adjacent twice loading is that 0.091nm, FBG2 are 0.076nm, loads back two rate of curve for the second time and diminishes, and the wavelength shift of FBG1 is 0.058nm, and the wavelength shift of FBG2 is 0.05nm.
Shown in Figure 8, three measuring points are with the external applied load change curve on the grating anchor rod body of rod, and the strain variation amount that reflects anchor rod body FBG1, FBG2, FBG3 under the different load gets development trend.
Shown in Figure 9, the data variation figure of the bolt shaft power that account temperature influence back optical fiber grating anchor ergometer is measured.
Can know that by figure an axle force data that carries out the optical fibre optical fibre grating anchor ergometer after the temperature compensation approaches the real load value more.Load for the first time wherein that anchor ergometer axle power is 6.36kN before one temperature compensation of 6.53kN measuring point, carry out that bolt shaft power is 6.51kN after the temperature compensation.It is thus clear that the method to adopting fiber grating is accurately measured bolt shaft power, it is necessary that fiber grating is carried out temperature compensation.