JP2004190478A - Tunnel reinforcing material separation detecting method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tunnel reinforcing material separation detecting method and a device for accurately measuring separation of a reinforcing material in a reinforcing place in a tunnel at a remote point. <P>SOLUTION: When reinforcing an inner wall surface of a tunnel lining 3 by a reinforcing material 31, after confirming a position of a crack 4, an optical fiber 2 is arranged in the direction orthogonal to the crack 4 on a surface of the reinforcing material 31 after finishing reinforcement, and two points are adhered and fixed by a fixing member 5. A strain measuring instrument 6 for measuring strain of the optical fiber 2 in a separation monitoring position and an arithmetic processing unit 7 are connected to a starting end part of the optical fiber 2. The strain measuring instrument 6 inputs the strain to the arithmetic processing unit 7 by measuring the strain of the optical fiber 2 in the separation monitoring position. The arithmetic processing unit 7 stores the strain measured by the strain measuring instrument 6, and compares strain measured last time with strain measured this time always or with every specific time, and detects separation of the reinforcing material 31 by detecting a state of changing to compression strain from tensile strain. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a method and an apparatus for detecting peeling of a tunnel reinforcing material for detecting peeling of a reinforcing material reinforcing an inner wall surface of a tunnel.

  2. Description of the Related Art Conventionally, inspection of an aged tunnel largely depends on visual inspection and destructive inspection in general. Inspections for cracks in road tunnels are conducted mainly by visual inspection, with workers walking in the tunnel or using aerial vehicles. In addition, core borings are used for exploration of cavities on the back of the lining and measurement of the lining pressure.

  In addition, in the case of railway tunnels, inspections, so-called general inspections, are performed once every two years or less, irrespective of the type of the tunnels, new or old, and structural type. This general inspection is mainly conducted visually on foot, and is conducted with the purpose of finding cracks on the lining surface, breaks in the lining material such as brick concrete blocks, leaks of water, etc. Have been.

  For the places where abnormalities such as abnormalities are found in the above general inspection, it is necessary to investigate the cause of the abnormalities and take appropriate measures. Has been taken.

  As a result of the crack inspection of the tunnel as described above, a reinforcing work such as fixing a reinforcing material such as a fiber sheet with an adhesive is performed at a place where the reinforcing is necessary. At the places where this reinforcement work was performed, the peeling of the fiber sheet was visually inspected similarly to the case of the crack inspection.

On the other hand, recently, monitoring of a structure using a carbon fiber sheet having electrical conductivity as a reinforcing material, and measuring the change in the electric resistance of the carbon fiber thread to detect fatigue and deterioration of the structure. A method has been considered (for example, see Patent Document 1). This is based on the fact that the single yarn of the carbon fiber sheet breaks and the electrical resistance changes in accordance with the fatigue or deterioration state of the structure.
JP-A-10-253561

  In the conventional visual inspection method for tunnel cracks described above, when performing a crack inspection, since the inside of the tunnel is dark, the probability of overlooking the deformation of the tunnel wall surface is high, and it is difficult to grasp the deformation of high places such as arches, In addition, there is a problem in that the obtained test results have individual errors and the like, and the objectivity is poor.

  Further, even when a crack in a tunnel is reinforced with a fiber sheet, an abnormality in the reinforced portion must be visually inspected, which has the same problem as in the crack inspection.

  In addition, using a carbon fiber sheet having electrical conductivity as a reinforcing material, a structure monitoring method that detects fatigue, deterioration of the structure by measuring the change in the electrical resistance of the carbon fiber thread, When electric facilities such as overhead lines are provided as in a railway tunnel, there is a problem in using a carbon fiber sheet as a conductor. That is, when the carbon fiber sheet is peeled from the wall surface, a short circuit accident may occur in the electric equipment due to the peeled carbon fiber sheet. Therefore, the carbon fiber sheet is used for a tunnel provided with the electric equipment. I can't.

  The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a method and an apparatus for detecting a tunnel reinforcing material peeling which can accurately measure the peeling of a reinforcing material at a reinforcing point in a tunnel at a remote point. I do.

  According to a first aspect of the present invention, there is provided a tunnel reinforcing member peeling detecting method for fixing an optical fiber to a surface of a reinforcing material which reinforced a wall surface in a tunnel, measuring a relationship between a distortion and a position of the optical fiber, and detecting peeling of the reinforcing material. At the same time, while applying tension to the surface of the reinforcing material on the inner surface of the tunnel while fixing so that one fixed end is located on the crack, the strain of the optical fiber at the peeling monitoring position is measured with a strain measuring instrument. And detecting a state in which the strain at the peel monitoring position has changed from a tensile strain to a compressive strain to detect the peeling of the reinforcing material.

  According to a second aspect of the present invention, there is provided a tunnel reinforcing member peeling detection device for fixing an optical fiber to a surface of a reinforcing material which reinforces a wall surface in a tunnel, measuring a relation between a strain and a position of the optical fiber, and detecting peeling of the reinforcing material. A fixing means for fixing the optical fiber so that one fixed end is positioned on the crack while applying tension to the surface of the reinforcing material on the inner surface of the tunnel; and a strain measurement for measuring the strain of the optical fiber at the separation monitoring position. And the storage means for storing the strain measured by the strain measuring instrument, and the strain measured this time by the strain measuring instrument is compared with the strain at the previous measurement stored in the storing means, and the strain is measured. Means for detecting a state in which the strain has changed from tensile strain to compressive strain and detecting peeling of the reinforcing material.

  A third invention is characterized in that, in the second invention, the optical fiber is fixed by bending a plurality of times by the fixing means.

  According to the present invention, when detecting the separation of the reinforcing material that has reinforced the inner wall surface of the tunnel lining, an optical fiber is disposed on the surface of the reinforcing material in a direction orthogonal to the crack, and one of the optical fibers is fixed on the crack. Since the end of the optical fiber is fixed so as to be located and the position where the strain of the optical fiber changes from the tensile strain to the compressive strain is detected, the separation of the reinforcing material can be reliably detected.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(1st Embodiment)
FIG. 1 is a diagram showing a configuration of a tunnel crack detection device according to a first embodiment of the present invention. In FIG. 1, an optical fiber 2 is laid on the inner wall along the longitudinal direction of the tunnel 1 in order to detect the progress of a crack in the tunnel lining. When the optical fiber 2 is laid, the optical fiber 2 is fixed to the wall surface with an adhesive so as to straddle the crack 4 of the tunnel lining 3 and not loosen as shown in FIG. In this case, the optical fiber 2 is bonded and fixed to the wall surface by, for example, a fixing member 5 on both sides straddling the crack 4, and a tension is applied between the fixed portions so as not to loosen. The fixed interval of the optical fiber 2 is preferably as close as possible to the width of the crack 4, but is set according to the distance resolution of the optical fiber 2.

  When the distance resolution of the optical fiber 2 is long, the fixed interval is shortened by folding back and fixing as shown in FIGS. 3 (a) and 3 (b). FIG. 3A shows a case where the optical fiber 2 is turned four times to form a loop 2a of 2.5 turns (five). Each turning point of the optical fiber 2 is fixed to a wall surface with an adhesive using a fixing member 5 having a predetermined length.

  FIG. 3B shows a case where two fixing members 5 are provided on both sides of the crack 4, and the optical fiber 2 is wound around the fixing members 5 to form 2.5 (five) loops 2 a. This is an example. The optical fiber 2 is fixed by an adhesive at a place where the optical fiber 2 is wound around the fixing member 5.

  When the optical fiber 2 is folded back to form a loop 2a of 2.5 turns (five) as described above, for example, even if the distance resolution of the optical fiber 2 is 2 m, the optical fiber 2 is fixed to the crack 4 The spacing can be 1/5, 40 cm.

  When there are a plurality of cracks 4, the optical fiber 2 between the next crack 4 is loosened, that is, a play is provided so that the tension of the optical fiber 2 at each crack 4 does not affect each other.

  A distortion measuring instrument 6 such as an optical fiber loss distribution measuring instrument (OTDR: Optical Time Domain Reflectometry) or a strain distribution measuring instrument (BOTDR: Brillouin Optical Time Domain Reflectometry) is connected to the starting end of the optical fiber 2. At the end of the optical fiber 2, a termination loop (not shown) is provided. The strain measuring instrument 6 is connected to the optical fiber 2 outside the tunnel, for example, at a remote location. The measurement result of the distortion measuring device 6 is input to the arithmetic processing device 7. The arithmetic processing device 7 is for obtaining the width of the crack 4 from the measured value of the strain measuring device 6, and details thereof will be described later.

  Next, a strain distribution measuring device (BOTDR) used as the strain measuring device 6 will be described. This strain distribution measuring device (BOTDR) measures the amount of strain applied to the optical fiber by analyzing the scattered light of the optical fiber. The frequency shift of the backward Brillouin scattered light, that is, the Brillouin scattering from the optical frequency of the incident light is measured. Focusing on the fact that the value obtained by subtracting the center frequency of the optical spectrum changes with the tensile stress applied to the optical fiber, that is, the elongation strain of the optical fiber, which is the relative elongation due to the equivalent tensile stress, and from the amount of change in the Brillouin frequency shift, The strain distribution of an optical fiber (or optical cable) is measured.

  The BOTDR receives a pulse from one end of the optical fiber and detects the Brillouin scattered light and the backscattered Rayleigh scattered light generated in the optical fiber with good sensitivity by a coherent detection method. At this time, utilizing the fact that the Brillouin scattered light shifted upward and downward with respect to the optical frequency of the incident pulse light by the interaction between the light wave of the scattered light and the sound wave in the optical fiber is detected, The strain distribution of the optical fiber is measured from the frequency shift distribution.

  FIG. 4 is a diagram showing a basic configuration of the distortion distribution measuring device (BOTDR) 10. The CW light of the optical frequency ν emitted from the light source 11 undergoes a frequency shift of Δν by the optical frequency shifter 12, and is incident from one end of the optical fiber 13 to be measured as pulse light of the optical frequency ν + Δν. Scattered light is generated in the optical fiber 13 by the incidence of the pulse light. Of the scattered light, the backscattered light is multiplexed with the CW light (local light) having the optical frequency ν, and is incident on the detector 14.

Since the frequency of the Brillouin scattered light is shifted by the Brillouin frequency shift ν _{B with} respect to the incident pulse light, the frequency shift amount Δν of the optical frequency shifter 12 is set to ν _B , so that the Brillouin back scattered light included in the back scattered light is Only can be detected.

By repeatedly performing the measurement while changing the frequency shift amount of the optical frequency shifter 12, the Brillouin spectrum at each position in the longitudinal direction of the optical fiber, that is, the distribution of the Brillouin frequency shift ν _B can be measured. The Brillouin frequency shift ν _B changes in proportion to the strain generated in the optical fiber. The relationship is shown in the following equation (1).

ν (ε) = ν _B (0) × (1 + K × ε) (1)
ν (ε): frequency of the maximum level of the measured Brillouin spectrum ν _B (0): intrinsic Brillouin frequency shift of the optical fiber
(Zero distortion frequency)
K: strain coefficient ε: strain amount (%)
The strain measuring device 6 such as the strain distribution measuring device 10 measures the strain of the optical fiber in the crack monitoring section, and inputs the measured value to the arithmetic processing device 7. The arithmetic processing unit 7 includes, for example, a CPU (central processing unit) 21, an input device 22, a storage device 23, a display device 24 and the like as shown in FIG. It should be noted that a printer (not shown) for printing calculation results and the like may be provided as necessary. The storage device 23 is provided with various memories such as an initial distortion memory 25, an initial crack width memory 26, a distortion / width table (strain change and crack width change correspondence table) 27, and a data memory 28.

  The initial strain memory 25 measures and stores the optical fiber strain (initial strain) with respect to each crack 4 when the optical fiber 2 is installed by the strain measuring device 6, and the initial crack width memory 26 stores each crack. The initial crack width for No. 4 is measured and stored. Further, the strain / width table 27 stores the correspondence between the previously measured optical fiber strain value change amount and the crack width change amount.

FIG. 6 is a graph showing an example of the relationship between the previously measured optical fiber strain value change amount (με) and the crack width change amount (mm), and FIG. 7 shows a part of the measured data by numerical values. The straight line in FIG. 6 is obtained by linearly approximating the above measured data. The measured values as shown in FIGS. 6 and 7 are input to the CPU 21 of the arithmetic processing unit 7, and the CPU 21 uses the measured values, for example, to determine the relationship between the change amount of the optical fiber strain value (με) and the change amount of the crack width (mm). Is created, for example, by linear approximation, and stored in the storage device 23 as the distortion / width table 27. As a result, assuming that a crack width change amount is y and an optical fiber strain value change amount is X, the crack width change amount y is
y = aX
Can be obtained by the following equation. Note that “a” in the above equation is a coefficient indicating the relationship between the amount of change in the crack width and the amount of change in the optical fiber distortion value.

Next, the operation of the arithmetic processing unit 7 in the above embodiment will be described with reference to the flowchart shown in FIG.
First, the CPU 21 in the arithmetic processing unit 7 sets a process number N (indicating a measurement position) (step A1), and measures the strain of the optical fiber 2 in each crack monitoring section by the strain measuring device 6 (step A2). , The position X _N on the optical fiber 2 corresponding to the process number, the initial strain value ε _N0 , and the initial crack width g _N0 are obtained (step A3). Then obtains the distortion value epsilon _N corresponding to crack position (step A4), to obtain the distortion change amount [Delta] [epsilon] _N of the initial strain value epsilon _N0 from the strain value epsilon _N is subtracted (step A5). Next, the CPU 21 substitutes the strain change amount Δε _N into “the relationship between strain and crack width” stored in the strain / width table 27 in advance, and acquires the crack width change amount Δg _N (step A6). ). The current crack width (estimated value) g _N is obtained by adding the initial value g _N0 of the crack width to the crack width change amount Δg _N (step A7). The crack width g _{N is made} to correspond to the time t and stored in the data memory 28 as data g (N, t) (step A8).

Then, the crack width g (N, t) and the crack width change rate (g (N, t) -g (N, t-1)) are compared with the standard crack width gA and the standard crack width change rate ΔgA. Then, it is evaluated whether it is equal to or more than the reference value (step A9). That is,
g (N, t)> gA
g (N, t) -g (N, t-1)> ΔgA
However, “t−1” means one time before or a certain period before.

Is evaluated to determine whether the crack width g (N, t) is equal to or greater than the reference value gA and whether the crack width change rate is equal to or greater than the reference crack width change rate ΔgA.

  As a result of the above evaluation, if the crack width g (N, t) and the crack width change rate are not equal to or larger than the reference value, the position is changed, that is, the value of N is changed and the same processing as described above is executed. (Step A10). Then, after the measurement processing is completed, the measurement result is displayed on the display device 24 and printed as necessary.

  If one or both of the crack width g (N, t) and the crack width change rate are equal to or more than the reference values as a result of the evaluation in step A9, an alarm is issued, a message indicating the alarm, and a measurement. The value is displayed on the display device 24 (step A11). In this case, the information indicating the danger may be further transmitted from the arithmetic processing unit 7 to the monitoring center in a wired or wireless manner.

  The strain measuring device 6 and the arithmetic processing device 7 may be connected to the optical fiber 2 at all times. For example, the strain measuring device 6 and the arithmetic processing device 7 may be connected to the optical fiber 2 to detect a crack width during a periodic inspection. good.

  As described above, the measurement result of the strain measuring device 6 is input to the arithmetic processing unit 7, and the crack width is obtained from the relationship between the strain and the crack width which is measured in advance and stored in the strain / width table 27. Crack width can be detected with high accuracy.

(2nd Embodiment)
Next, a second embodiment of the present invention will be described.
In the second embodiment, as shown in FIG. 9, when the inner wall surface of the tunnel lining 3 is reinforced by a reinforcing material 31 such as a fiber sheet, the separation of the reinforcing material 31 is detected by using the optical fiber 2. This is an example of the case.

  When reinforcing the inner wall surface of the tunnel lining 3 with the reinforcing material 31, the positions of the cracks 4 are confirmed, and after the reinforcement is completed, the optical fiber 2 is arranged on the surface of the reinforcing material 31 in a direction orthogonal to the cracks 4. Then, two points are bonded and fixed with the fixing member 5. In this case, the optical fiber 2 is bonded and fixed using a fixing member 5 having a diameter of, for example, about 60 mm so that one fixed end is located on the crack 4. A tension is applied between the fixed portions of the optical fiber 2 so as not to loosen, and the fixing interval is set according to the distance resolution of the optical fiber 2. When the distance resolution of the optical fiber 2 is long, the fixed interval is shortened by folding back and fixing as shown in FIG. Further, the optical fiber 2 is similarly fixed by the fixing member 5 so that one fixed end is located on the crack 4 in the other reinforcing portion.

  At the start end of the optical fiber 2, a strain measuring instrument 6 for measuring the strain of the optical fiber 2 at the peel monitoring position and an arithmetic processing unit 7 are connected, and at the end of the optical fiber 2, a termination processing loop (FIG. (Not shown).

  In the above configuration, when the tunnel 1 is deformed and the width of the crack 4 is widened, a tensile strain is generated in the reinforcing member 31 as shown by an arrow in FIG. 10 and, accordingly, a tensile strain is generated in the optical fiber 2. . The tensile strain of the optical fiber 2 is measured by the strain measuring device 6, and the measured value is input to the arithmetic processing device 7.

  Thereafter, the deformation of the tunnel 1 progresses, and the tensile strain of the optical fiber 2 increases as the width of the crack 4 increases, and the reinforcing material 31 eventually peels off from the inner wall surface of the tunnel lining 3 as shown in FIG. . When the reinforcing member 31 peels off from the inner wall surface of the tunnel lining 3, the fixing member 5 at the peeling start position, that is, the position of the crack 4 floats together with the reinforcing member 31 from the wall surface, so that the tension of the optical fiber 2 decreases. Apparently, compression distortion occurs. Therefore, the distortion of the optical fiber 2 measured by the distortion measuring device 6 is stored in the memory by the arithmetic processing unit 7, and the previously measured distortion is compared with the previously measured distortion at all times or at predetermined time intervals. By detecting the position where the tensile strain changes to the compressive strain, the position where the reinforcing material 31 has peeled can be detected.

  FIG. 12 shows the state of change in the strain distribution of the optical fiber 2 due to the separation of the reinforcing material 31 using a large tunnel as a model. The horizontal axis indicates the position (mm) of the optical fiber, and the vertical axis indicates the optical fiber The strain (με) is shown. FIG. 12A shows a state in which the optical fiber 2 is strained before the reinforcing material 31 is peeled off, and a large tensile strain is generated at the position where the crack 4 is generated. FIG. 12B shows a state in which the optical fiber 2 is distorted when the reinforcing member 31 is separated from the wall surface, and a large compressive strain is generated at the separated position.

  When the reinforcing member 31 peels off from the inner wall surface of the tunnel lining 3 as described above, the tension of the optical fiber 2 decreases because the fixing member 5 at the peeling start position floats from the wall surface together with the reinforcing member 31 and apparently decreases. Since a compressive strain occurs, the position where the reinforcing material 31 has peeled off can be reliably detected by detecting the position where the tensile strain changes to the compressive strain by the arithmetic processing unit 7. Also, since the point at which the optical fiber changes from tensile strain to compressive strain is detected, the peeling of the reinforcing material 31 can be detected without using a conductive material as the reinforcing material 31, and electric equipment is installed. It can be used safely even in railway tunnels.

  The detection result of the arithmetic processing unit 7 is displayed on the display device as in the first embodiment, and is printed if necessary. Further, when the arithmetic processing device 7 detects the separation of the reinforcing member 31, an alarm is issued and information on the position where the reinforcing member 31 has separated is displayed on the display device 24. In this case, danger information indicating that the reinforcing member 31 has peeled off may be transmitted from the arithmetic processing unit 7 to a monitoring center by wire or wirelessly.

  The strain measuring device 6 and the arithmetic processing device 7 may be connected to the optical fiber 2 at all times. For example, the strain measuring device 6 and the arithmetic processing device 7 may be connected to the optical fiber 2 to detect peeling of the reinforcing member 31 during a periodic inspection. You may do it.

The figure which shows the structure of the tunnel crack detection apparatus which concerns on one Embodiment of this invention. FIG. 3 is a diagram showing a laid state of the optical fibers in the embodiment. The figure which shows the example of loop attachment of the optical fiber with respect to the crack in the embodiment. FIG. 2 is a diagram showing a basic configuration of a distortion distribution measuring device (BOTDR) according to the embodiment. FIG. 2 is a block diagram showing a configuration example of an arithmetic processing device in the embodiment. 5 is a graph showing a relationship between a previously measured optical fiber strain value change amount and a crack width value change amount in the embodiment. The figure which shows the relationship between the optical fiber distortion value change amount and the crack width value change amount measured in advance in the embodiment by numerical data. 4 is a flowchart showing the operation of the arithmetic processing device according to the embodiment. The figure which shows the laying state of the optical fiber of the tunnel reinforcement peeling inspection apparatus which concerns on 2nd Embodiment of this invention. The figure in the same embodiment which shows the tensile strain generation state before the peeling of the reinforcement material. The figure which shows the compression strain state when the reinforcement material in the same embodiment peels off from the wall surface. (A) is a figure which shows the tensile strain generation state of the optical fiber before the reinforcing material peels off in the embodiment, (b) is a figure which shows the compressive distortion generating state of the optical fiber when the reinforcing material peels off from the wall surface.

Explanation of reference numerals

  DESCRIPTION OF SYMBOLS 1 ... Tunnel, 2 ... Optical fiber, 3 ... Tunnel lining, 4 ... Cracking, 5 ... Fixing member, 6 ... Strain measuring device, 7 ... Processing device, 10 ... Strain distribution measuring device, 11 ... Light source, 12 ... Light Frequency shifter 13, 13 optical fiber under measurement, 14 detector, 21 CPU, 22 input device, 23 storage device, 24 display device, 25 initial distortion memory, 26 initial crack width memory, 27 ... Strain / width table, 28 ... Data memory, 31 ... Reinforcing material.

Claims (3)

An optical fiber is fixed to the surface of a reinforcing material that reinforces a wall surface in a tunnel, and in a tunnel reinforcing material peeling detection method for detecting the peeling of the reinforcing material by measuring the relationship between the strain and the position of the optical fiber,
Affixing the optical fiber to the surface of the reinforcing material on the inner surface of the tunnel so that one fixed end is located on the crack while applying tension, and measuring the strain of the optical fiber at the peel monitoring position with a strain measuring instrument, A method for detecting peeling of a tunnel reinforcing material, comprising detecting a state in which a strain at a peel monitoring position changes from a tensile strain to a compressive strain to detect peeling of a reinforcing material. An optical fiber is fixed to a surface of a reinforcing material that reinforces a wall surface in a tunnel, and a tunnel reinforcing material peeling detection device that detects a peeling of the reinforcing material by measuring a relationship between a strain and a position of the optical fiber,
A fixing means for fixing the optical fiber on the surface of the reinforcing material on the inner surface of the tunnel so that one fixed end is located on the crack while applying tension, and a strain measuring instrument for measuring the strain of the optical fiber at the peeling monitoring position. A storage means for storing the strain measured by the strain measuring instrument, and comparing the strain measured this time by the strain measuring instrument with the strain at the previous measurement stored in the storage means, and A means for detecting a state in which the tensile strain has changed from a compressive strain to a compressive strain and detecting peeling of the reinforcing material.   The device for detecting separation of a tunnel reinforcing member according to claim 2, wherein the fixing means fixes the optical fiber by bending the optical fiber a plurality of times.

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