JP2001227994A - Assembling method for optical fiber sensor and optical fiber sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently assemble an optical fiber to a structure formed with unevenness on the surface such as a concrete structure. SOLUTION: In this assembling method for the optical fiber sensor, a flexible deformation transmission member 3 is fixed to the structure 1 in a line state, while the optical fiber 4 is integrally fixed to the deformation transmission member 3 along the deformation transmission member 3. Thereby, the optical fiber 4 is integrated with the structure 3 through the deformation transmission member 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for assembling an optical fiber sensor for detecting deformation of various structures such as concrete structures such as roads, dams, embankments and buildings, and an optical fiber sensor.

[0002]

2. Description of the Related Art Conventionally, for example, the detection of deformation of a concrete structure such as a retaining wall, a bridge, or a building constructed on a slope such as a road, a dam, an embankment, or a cliff can detect the deformation of the structure. Generally, a method of installing a displacement meter (an electric sensor is used) such as an extensometer or an inclinometer at a location having a characteristic and performing point measurement is used.

[0003]

However, the above-described deformation detection method has the following problems. (1) Since it is point measurement, it is difficult to grasp the state of deformation such as the scale of deformation of the entire structure. In order to grasp the state of deformation of the entire structure, it is necessary to install displacement meters such as extensometers and inclinometers on the entire structure, and the number of installations becomes enormous, so the labor required for installation becomes enormous With
In order to grasp the state of deformation such as the deformation scale of the entire structure, comprehensive analysis is performed from measurement data from a large number of displacement meters, and it takes time to grasp. (2) An electric sensor used as a displacement meter such as an extensometer or an inclinometer requires a power supply for the sensor itself, and thus requires much maintenance and management. (3) Since electric sensors used as displacement meters such as extensometers and inclinometers are easily affected by electromagnetic noise such as induced current, electromagnetic waves radiated from electric devices installed in buildings such as buildings, for example. May cause erroneous measurement.
Further, if an electromagnetic wave shielding structure is adopted for the displacement meter in order to prevent erroneous measurement, the cost will increase significantly. (4) Wiring of a signal line for collecting measurement data of a displacement meter such as an extensometer and an inclinometer is required in addition to the power supply line, and the construction is troublesome.

As a displacement sensor that is not affected by electromagnetic noise such as induced current, attention has been paid to a sensor using an optical fiber, and the continuous distribution of the amount of strain in the longitudinal direction of the optical fiber can be observed with high precision. As a method for performing this, a method has been developed that utilizes the fact that the frequency shift amount of Brillouin scattered light, which is one of the nonlinear phenomena, depends on the distortion of the optical fiber. However, as an optical fiber sensor for detecting deformation of a structure, it is excellent in workability such as attachment to a structure, and efficiently applies deformation of the structure to an optical fiber to deform such as bending, elongation, breakage, etc. It is required that the structure be able to act efficiently.
Until now, there has been no suitable one satisfying these conditions.
Furthermore, there is also a demand for cost reduction, and it has been necessary to develop an optical fiber sensor that satisfies these conditions.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is simple in construction for a structure. It is an object of the present invention to provide a method of assembling an optical fiber sensor that can easily grasp the state of the deformation at low cost.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method for assembling an optical fiber sensor for detecting deformation of a structure by light, comprising arranging a flexible deformation transmitting member on the structure and fixing the member. A method for assembling an optical fiber sensor is characterized in that an optical fiber is attached to the deformation transmitting member so that the optical fiber is attached to a structure via the deformation transmitting member. According to the method for assembling an optical fiber sensor of the present invention, an optical fiber sensor that detects deformation of a structure by light is assembled by laying an optical fiber along a structure via a deformation transmitting member. . In this optical fiber sensor, when the structure is deformed, the optical fiber provided so as to be attached to the structure via the deformation transmitting member is integrally deformed with the structure. Here, as a result of inputting light into the optical fiber and observing the return light, the deformation of the structure can be detected by detecting an increase in the loss of the optical fiber and Brillouin scattered light.

In the optical fiber sensor assembled according to the present invention, the fact that the frequency shift amount of the Brillouin scattered light, which is one of the non-linear phenomena, depends on the distortion of the optical fiber. By observing the continuous distribution with high accuracy, it is possible to detect and monitor the deformation of the structure. That is, the wavelength of Brillouin scattered light, which is one of the backscattered light generated when the test light enters the strained optical fiber, deviates from the wavelength of the test light incident on the optical fiber. Thus, the amount of distortion of the optical fiber can be grasped. In addition, an outline of a strain generation position of the optical fiber can be grasped by a time (return time) from reception of the test light to reception and observation of the Brillouin scattered light.

For example, an optical pulse tester (so-called BOTDR) for observing Brillouin scattered light is connected to an optical fiber fixed to a structure via a deformation transmitting member, and the optical fiber is connected to the optical fiber using the optical pulse tester. By observing Brillouin scattered light by performing an optical test (observation of test light incidence and return light), deformation of a structure can be detected. That is, the optical fiber fixed to the structure via the deformation transmitting member is given a longitudinal elongation strain as an initial strain, and the structure is stretched, cracked (cracked), deformed by compressive deformation, etc., and deformed in the longitudinal direction of the optical fiber. When the amount of strain changes, the deformation of the structure can be detected by observing the Brillouin scattered light by an optical test of the optical fiber. "The distortion amount changes"
“Elongation strain of the optical fiber in the longitudinal direction due to deformation of the structure increases or decreases compared to the initial strain. By detecting a change in the amount of strain (hereinafter referred to as“ stretch strain ”), Can be detected. In other words, when the optical fiber fixed to the structure is deformed integrally with the deformation of the structure and is subjected to expansion and contraction, the expansion and contraction is detected by an optical test of the optical fiber, and the deformation of the structure is detected. Can be detected. In addition, the amount of distortion of the optical fiber can be ascertained from the observed frequency shift amount of the Brillouin scattered light, whereby the degree of deformation of the structure can be ascertained. Further, the deformation position of the structure can be measured from the observed return time of the Brillouin scattered light. However, in the present invention, it is also possible to adopt a configuration in which the deformation of the structure is observed by detecting only the occurrence of the elongational strain of the optical fiber fixed to the structure without giving the initial strain as the expansion and contraction strain. According to the assembling method of the present invention, the optical fiber sensor can be easily assembled over a wide range of the structure by providing one optical fiber so as to be attached to the structure via the deformation transmitting member. There are advantages. In addition, in the optical fiber sensor assembled by one optical fiber, the deformation of the structure can be detected and monitored over a wide range by the optical test of the single optical fiber.

In order to integrate an optical fiber such as an optical fiber cable into various concrete structures such as a road, a building such as a building, a dam, an embankment, and a bridge, for example, an anchor driven into a concrete wall is used. It is conceivable to fix the optical fiber directly by using the fixing parts of this type.However, in such a fixing method, lateral pressure is easily applied to the optical fiber, and unnecessary bending or expansion / contraction strain is applied, so that the optical test of the optical fiber can be performed. This may cause noise light that may be an obstacle. To fix the optical fiber cable directly to the concrete wall, flatten the unevenness of the concrete wall,
It is necessary to sufficiently perform pre-processing such as cleaning, and there is a dissatisfaction that this pre-processing is extremely troublesome. Problems associated with fixing optical fibers, such as lateral pressure applied by fixed components to optical fibers, flattening of irregularities on structures, cleaning, etc., are not limited to concrete structures, but are common to structures other than concrete structures. That is.

Therefore, as a result of diligent studies, the present inventor firstly lays and fixes a flexible deformation transmitting member on a structure, and fixes the structure so that an optical fiber is attached to the deformation transmitting member. Configuration (method) for integration. In this method, since the optical fiber is integrated with the structure via the deformation transmitting member, the direct fixing force on the structure acts only on the deformation transmitting member and does not act on the optical fiber. For fixing the deformation transmitting member to the structure, an appropriate means may be selected and adopted according to the state of the surface of the structure, for example, adhesion with an adhesive or fixing with a fixing component such as an anchor. The fixing of the optical fiber to the deformation transmitting member fixed to the structure is laid along the deformation transmitting member,
It can be performed by a simple method such as bonding, and the workability can be improved. Furthermore, in the configuration in which the optical fiber is integrated with the structure via the deformation transmitting member, even if there are irregularities or cracks on the surface of the structure, a smooth optical fiber mounting surface can be formed by attaching the deformation transmitting member. As a result, the optical fiber can be efficiently attached to and integrated with the structure.

However, it is not always necessary to integrate the entire length of the deformation transmitting member with the structure, and a portion that is not fixed to the structure may exist in the middle. Even if a part that is not fixed to the structure is present in the middle, for example, the deformation transmitting member of the part that is not fixed is deformed by deformation of the structure, and this part has initial strain. If the optical fiber provided so as to be laid in such a manner that expansion and contraction is applied thereto, deformation of the structure can be detected. It is not always necessary to fix the entire length of the optical fiber integrally to the deformation transmitting member, and the fixing to the deformation transmitting member may be partial. The optical fiber is, for example, at least a region (longitudinal region) provided in a structure where there is a high possibility of deformation.
However, it is sufficient that the deformation of the structure is transmitted through the deformation transmitting member, and the deformation of the structure can be detected. In order to more reliably and accurately detect deformation of a structure, a deformation transmitting member is integrally fixed to the structure over its entire length, and an optical fiber is integrated with the deformation transmitting member over its entire length. It is desirable to fix it.

In the present invention, it is more preferable to adopt the following configuration. According to a second aspect of the present invention, in the method of assembling an optical fiber sensor according to the first aspect, a tape-shaped deformation transmitting member is fixed to the structure, and the optical fiber is fixed to the deformation transmitting member. Features. In this optical fiber sensor assembling method, since the tape-shaped deformation transmitting member is used, the deformation transmitting member can be disposed and fixed so as to be laid on the structure, and the deformation transmitting member can be spread over a wide range of the structure. The work of setting up can be performed efficiently. In addition, the tape-shaped deformation transmitting member can be easily laid on the structure and easily configured to deform following the deformation of the structure, so that the deformation of the structure can be efficiently performed with little loss. Good transmission to optical fiber. When the tape-shaped deformation transmitting member is bonded and fixed to the structure using, for example, an adhesive, a wide bonding area can be secured, and it can be integrated into the structure almost in a close contact state,
Since the distortion of the deformation of the structure is efficiently transmitted to the optical fiber, the optical fiber can be efficiently subjected to bending deformation and stretching distortion.

An optical fiber sensor according to a third aspect of the present invention is an optical fiber sensor for detecting deformation of a structure by light, wherein the deformation transmission is provided substantially perpendicular to the extending direction of the structure. A member is erected between the structure and a structure existing at a position separated from the structure and fixed to both structures, and an optical fiber is attached to the deformation transmitting member. It is characterized by being provided. In this optical fiber sensor, deformation or displacement of one or both of the structures on which the deformation transmitting member is erected causes the deformation transmitting member to be deformed (elongated or compressed, slackened, etc.) in the longitudinal direction. An optical fiber provided so as to be attached to the deformation transmitting member is also subjected to a stretching strain. If an initial strain is applied to the optical fiber, deformation of the structure in the compression direction can be detected. Then, by performing an optical test on the optical fiber and observing Brillouin scattered light, it is possible to detect deformation of the structure. Here, the deformation or displacement of the structure that gives the expansion / contraction strain to the deformation transmitting member is not limited to the increase or decrease in the separation distance between the two structures on which the deformation transmitting member is installed. Includes all that increase or decrease the separation distance between the fixed positions of the deformation transmitting member with respect to both structures, such as deformation and displacement in the direction along the structure extending direction. The optical fiber is not required to be stretched between the structures because it is sufficient that the optical fiber is subjected to expansion and contraction by deformation integrally with the deformation transmitting member. By providing with a distortion, it is possible to detect the separation between the structures on which the deformation transmitting member is erected.

[0014] More specifically, the optical fiber sensor is provided with at least one of, for example, between opposing side walls of a road, between buildings, between columns or between beams, or between structural members constituting a bridge girder of a bridge. The optical fiber is fixed and integrated with the deformation transmitting member which is erected and fixed so as to be perpendicular or almost perpendicular to the extending direction of the structure. The opposing side walls of the road, the building walls, columns and beams, and the structural materials constituting the bridge girder of the bridge are part of structures such as roads, buildings and bridges, and the opposing side walls of these roads Parts, building walls, pillars and beams, structural materials of bridge girders, etc. can also be considered as structures.
Deformation transmission members installed between the opposing side walls of the road, between the pillars and beams of the building, and between the structural materials constituting the bridge girder of the bridge, etc., are separated from each other between the structures, specifically, the same structure. That is, it is erected between the parts existing at the set positions. Deformation and displacement of the structure by the deformation transmitting members installed between the structures such as the side walls facing the road, the building materials such as the walls, columns and beams of the building, and the structural materials that make up the bridge girder of the bridge When the deformation in the longitudinal direction is given, the optical fiber integrated with the deformation transmitting member is subjected to expansion and contraction strain. Therefore, the deformation of the structure can be detected by observing the Brillouin scattered light in the optical test of the optical fiber. In addition, this makes it possible to detect deformation of structures such as roads, buildings, and bridges.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. 1 (a) and 1 (b), reference numeral 1
Is a structure, and here, a road made of a concrete structure having a ring-shaped cross section is exemplified. Reference numeral 2 denotes an optical fiber sensor, and a ceiling 1 of a road which is a structure 1.
a is provided in a laid state.

FIG. 2 is a sectional view showing a structure 1 (more specifically, a ceiling 1a) to which the optical fiber sensor 2 is fixed, and FIG. 3 is a perspective view showing a deformation transmitting member 3 constituting the optical fiber sensor 2. In this case, the structure 1 is omitted. As shown in FIGS. 2 and 3, the optical fiber sensor 2 includes a structure 1 (in FIGS. 2 and 3, specifically, a ceiling 1 of the structure 1).
a) a tape-shaped deformation transmitting member 3 laid in accordance with a);
The optical fiber 4 has a tape-shaped optical fiber 4 which is tightly fixed to the deformation transmitting member 3 by adhesion or the like and integrated. The optical fiber 4 is fixed to and integrated with the deformation transmitting member 3 in a state where an initial strain is applied. However, the deformation transmitting member 3
In order to detect deformation of the entire structure 1 with high accuracy, it is preferable to integrate the entire length of the structure 1 with the structure 1. The pipes and the like that are provided are installed so as to straddle these as appropriate, and are not integrated with the structure 1 at the installation locations as described above. However, since the deformation transmitting member 3 has excellent flexibility, it is easy to arrange the deformation transmitting member 3 while avoiding the recesses and projections existing in the structure 1 and the pipes arranged in the structure 1. In addition, the installation workability for the structure 1 can be improved. In order to detect the deformation of the entire structure 1 with high accuracy, it is preferable that the entire length of the optical fiber 4 be fixed to the deformation transmitting member 3. However, the present invention is not limited to this. The fixation to the deformation transmitting member 3 may be partial. Here, it is assumed that the deformation transmitting member 3 is integrated with the structure 1 over the entire length, and the optical fiber 4 is integrated with the deformation transmitting member 3 over the entire length.

The deformation transmitting member 3 is formed from a thin metal plate such as a thin stainless steel plate or a resin plate into a tape shape which can be easily deformed, and has excellent flexibility. Therefore, even if the deformation transmitting member 3 is fixed to the structure 1,
Is not restricted, and is deformed integrally with the structure 1.

In FIGS. 2 and 3, reference numeral 5 denotes a joining material, and reference numeral 6 denotes a stud. Each of the joining material 5 and the stud 6 functions as fixing means for fixing the deformation transmitting member 3 to the structure 1, and the deformation transmitting member 3 is provided on one surface in a layered manner. And a stud 6 that is inserted into the structure 1 through the deformation transmitting member 3.
And fixed to the structure 1 by the fixing force. The studs 6 are driven into a plurality of locations of the deformation transmitting member 3, so that when the structure 1 is deformed, the deformation transmitting member 3 is also integrally deformed with the structure 1.
As the joining material 5, for example, a structure 1 such as a resin foam such as an acrylic foam kneaded with an adhesive, or a resin foam containing no adhesive and having an adhesive layer provided on the surface thereof.
Adhesive and plastic materials are used. Therefore, the deformation transmitting member 3 is easily bonded and fixed to the structure 1 by pressing the bonding material 5 against the surface of the structure 1.

The optical fiber 4 is, for example, a sheet-type optical fiber cable having a structure in which an optical fiber (an optical fiber core wire or the like) is embedded and fixed in a resin, and has excellent flexibility. FIG. 4 shows an example of the optical fiber 4 used here. In FIG. 4, an optical fiber 4 is formed by laminating a bonding material 8 made of a resin foam such as an acrylic foam on one surface of a flexible resin film 7 such as a polyimide film. The optical fiber 9 (hereinafter, “internal optical fiber”) such as a fiber core is embedded and fixed, and has flexibility as a whole. As the bonding material 8, a resin foam such as an acrylic foam kneaded with an adhesive, a resin foam having no adhesive and a surface provided with an adhesive layer, or the like is employed. Further, as the bonding material 8, a material having plasticity is employed. As the internal optical fiber 9, a fiber having excellent durability, for example, a single-core carbon-coated optical fiber is used.

In the optical fiber sensor 2, since the optical fiber 4 is integrated with the structure 1 via the easily deformable deformation transmitting member 3, the deformation transmitting member 3 is deformed by the deformation of the structure 1. Then, the optical fiber 4 is also deformed integrally with the deformation transmitting member 3. After all, when the structure 1 is deformed, it is integrated with the structure 1 via the deformation transmitting member 3. The optical fiber 4 is also deformed integrally with the structure 1. Therefore, an optical pulse tester (BOTD) connected to one end of the optical fiber 4
R), an optical test (observation of test light incidence and return light) of the optical fiber 4 is performed, and the structure 1
Can be detected and monitored.

Next, an example of a method of assembling the optical fiber sensor 2 will be described. First, as shown in FIGS. 5A and 5B, the deformation transmitting member 3 is laid in a line shape on the structure 1 and fixed. In FIGS. 5A and 5B, the tape-shaped deformation transmitting member 3 in which the bonding material 5 having adhesiveness is fixed to one surface is adhered along the structure 1 while being pressed by a roller 10 or the like. Thus, the deformation transmitting member 3 adhered to the structure 1 is fixed to the structure 1 by driving the studs 6. Here, as the joining material 5, it is particularly preferable to employ a pressure-sensitive adhesive type made of a resin foam kneaded with a pressure-sensitive adhesive, and in this case, the joining material 5 Since the adhesive force is weak or not developed until it is pressed, for example, by positioning the structure 1 at a target fixed position and then pressing the structure 1 against the structure 1, the structure 1 is bonded to a position other than the target fixed position. There are advantages that inconvenience can be prevented and handling becomes easy.

The deformation transmitting member 3 is carried into the construction site while being wound around the drum 11, and is sequentially fixed to the structure 1 while unwinding from the drum 11. First, the deformation transmitting member 3 unwound from the drum 11 is successively adhered and fixed to the structure 1 while peeling off the easily peelable release paper 5b attached to the joining surface 5a of the joining material 5. Here, the deformation transmitting member 3 absorbs irregularities on the surface of the structure 1 by deformation of the layered joining material 5 made of resin foam when the structure 1 is pressed against the structure 1 by the roller 10 or the like.
After the bonding to the optical fiber 1 is completed, the surface opposite to the structure 1, that is, the lower surface in FIG. 5A forms a smooth optical fiber fixing surface 12 that is flat or gently curved. . Next, as shown in FIGS. 6A and 6B, the deformation transmitting member 3 which has been bonded and fixed to the structure 1 is completed.
Are sequentially fixed to the structure 1 with the studs 6.

5 (b) and 6 (b), the deformation transmitting member 3 is provided on both sides in the width direction (perpendicular to the longitudinal direction; upper and lower sides in FIGS. 5 (b) and 6 (b)). A tack fixing portion 3 which is a region extending over the entire length of the deformation transmitting member 3 in the longitudinal direction.
At a plurality of locations in the extending direction of b, tack driving holes 13 are formed, and the tack 6 is driven into the structure 1 using the driving holes 13. By the way, when the linear expansion coefficient between the structure 1 and the deformation transmitting member 3 is different, such as the deformation transmitting member 3 made of a concrete structure 1 and a stainless steel thin plate, the light of the optical fiber 4 is changed by the temperature change. This may cause detection noise in the detection of expansion and contraction strain by the test. For this reason, the driving positions of the studs 6 on the deformation transmitting member 3 are arranged along the extending direction of the deformation transmitting member 3 at intervals smaller than the detection resolution of the optical pulse tester, calculated from the linear expansion coefficient difference. It is preferable to set so that.

As shown in FIGS. 5A and 5B,
When the deformation transmitting members 3 are continuously fixed to the structure 1 such that the longitudinal ends of the deformation transmitting members 3 abut against each other, the deformation transmitting member 3 is elongated along the structure 1 without any gap. It is also possible to install them continuously on a scale.

After the fixing of the deformation transmitting member 3 to the structure 1 is completed, next, as shown in FIGS. 7 (a) and 7 (b),
By tightly fixing the optical fiber 4 to the deformation transmitting member 3, the optical fiber 4 is integrated with the structure 1 via the deformation transmitting member 3. The optical fiber 4 is laid on the deformation transmitting member 3 while being pressed by the roller 10 or the like, and the bonding material 8 (not shown in FIGS. 7A and 7B).
(See FIG. 4). here,
As the joining material 8, it is particularly preferable to adopt a pressure-sensitive adhesive type made of a resin foam in which a pressure-sensitive adhesive is kneaded. In this case, the joining material 8 is pressed against the deformation transmitting member 3. Since the adhesive force is weak or not developed until then, for example, by pressing after being positioned with respect to the deformation transmitting member 3, it is possible to prevent inconvenience such as adhering to a position other than the target position, and there is an advantage that handling becomes easy. is there. Since the optical fiber 4 is bonded and fixed to the smooth optical fiber fixing surface 12 formed by the deformation transmitting member 3 fixed to the structure 1, this fixing operation can be performed very efficiently and in a short time. it can. Further, even if there is a step or a gap in the joint portion between the deformation transmitting members 3 in the longitudinal direction, this can be absorbed by the deformation of the joining material 8, so that the optical fiber 4 is not locally bent or the like. It can be arranged in a laid state.

The optical fiber 4 is transported to a construction site while being wound around a drum 14, and is sequentially fixed to the deformation transmitting member 3 while unwinding from the drum 14. Drum 14
The optical fiber 4 unwound from the bonding material 8a
The release paper 8b, which is easily peelable, is sequentially adhered and fixed to the structure 1. Here, the optical fiber 4 is, for example, a portion where the deformation transmitting members 3 are connected to each other in the longitudinal direction by deformation of the layered bonding material 8 made of a resin foam during pressure bonding by the roller 10 or the like (FIG. 7B).
Since the unevenness such as the step of the connecting portion 15) can be absorbed, even if the connecting portion 15 has a step, it is bent in the middle of the optical fiber (such as the internal optical fiber 9 illustrated in FIG. 4) built in the optical fiber 4 even if the step is formed. The formation of a portion or the like can be prevented.

When the fixing of the optical fiber 4 to the deformation transmitting member 3 is completed, the optical fiber 4 is integrated with the structure 1 via the deformation transmitting member 3, and the optical fiber 4 is integrated by the deformation of the structure 1. It becomes deformed,
Thus, the optical fiber sensor 2 is completed.

FIG. 8 shows an example of a deformation detection system for detecting and monitoring deformation of a structure using the optical fiber sensor 2. The deformation detection system 20 includes an optical fiber sensor 2 assembled on structures 21A and 21B which are both roads (for convenience of explanation, the optical fiber sensor 2 assembled on the structure 21B is denoted by reference numeral 2a). The optical fiber 4 to be tested is subjected to an optical test (incident of test light and observation of return light) by an optical pulse tester 23 installed in a monitoring station 22 to detect deformation of the structures 21A and 21B,
To monitor. Here, a so-called BOTDR for observing Brillouin scattered light is used as the optical pulse tester 23.
A configuration for detecting and monitoring the deformation of the structures 21A and 21B, which are ring-shaped concrete roads, by observing the continuous distribution of the amount of strain in the longitudinal direction of the optical fiber with high accuracy. Will be described as an example. In FIG. 8, reference numerals 24 and 25 are both vertical shafts, and the structures 21A and 21B, which are access roads, extend from the vertical shaft 24 in different directions. The shaft 24 is in communication with the monitoring station 22 via a cableway 26 to the monitoring station 22.

In FIG. 8, the optical fiber 4 of the optical fiber sensor 2 assembled on the structure 21A is guided to the monitoring station 22 through the shaft 24 and the shaft 26, and is sent to the conversion unit 27 installed in the monitoring station 22. To the communication optical fiber cable 28. On the other hand, the optical fiber 4 of the optical fiber sensor 2a assembled on the structure 21B is connected to the communication optical fiber cable 30 by the conversion unit 29 installed in the shaft 24. The monitoring station 22
An optical switch 22a and a termination box 22b are installed,
At the optical switch 22a (core selection device), the optical fiber of the optical pulse tester 23 is connected to the optical fiber cable 2 for communication.
The optical fibers 4 of the optical fiber sensors 2 and 2a (specifically, the optical fiber inside the optical fiber 4 which is an optical fiber cable) are selectively switched and connected to the optical fibers 8 and 30. , Communication optical fiber cable 2
The optical pulse tester 23 is connected to the optical pulse tester 23 via the reference numerals 8 and 30 so that test light can be incident thereon.

The optical fiber sensors 2 and 2a indicated by broken lines in FIG. 8 are fixed to the ceilings of the structures 21A and 21B (the upper portions of the structures 21A and 21B in FIG. 8).
The structures 21A and 21B are assembled along the extending direction (axial direction of the road). In addition to the optical fiber sensors 2 and 2a, an optical fiber sensor 32 is also provided on the structures 21A and 21B which are roads. The optical fiber sensor 32 is a deformation transmitting member which is formed by folding the optical fiber 4 constituting the optical fiber sensors 2 and 2a at a position away from the shaft 24 and erected along the diametrical direction of the road. It is configured by wiring and fixing along 33 (primary plate). Deformation transmission member 33
Is made of a metal plate such as a thin steel plate, a resin plate, or the like, and is easily deformed in response to the deformation of the structures 21A and 21B, so as not to restrict the deformation of the structures 21A and 21B. It has become.

As shown in FIGS. 9 (a) and 9 (b), the deformation transmitting member 33 is specifically provided between the ceiling 21a and the bottom 21b of the road which is the structure 21A, 21B. In addition, both the ceiling part 21a and the bottom part 21b are fixed and integrated by fixing parts 35 such as anchor bolts. Ceiling 21a and bottom 21b
Functions as a part of the structures 21A and 21B, the deformation transmitting member 32 is bridged between the structures 21a and 21b which are separated from each other.

The optical fiber sensor 32 is folded at a point away from the shaft 24 and is routed in the middle of the optical fiber 4 wired toward the shaft 24 to a structure 21A which is a road.
It is pulled out in the direction along the diametrical direction of the path inside 21B, fixed to the plate-shaped deformation transmitting member 33 by bonding or the like, and integrated. The optical fiber 4 between the optical fiber sensors 32 is wired along the extending direction of the structures 21A and 21B (axial direction of the road), but is displaceable with respect to the structures 21A and 21B. Has been
The structures 21A and 21B are not affected by elongation deformation in the extending direction.

The leading end of the optical fiber 4 constituting the optical fiber sensor 32 in the drawing direction is connected to one of the structures 21b (FIG. 9).
(A) and (b) are folded around the R guide 34 installed near the bottom of the road (in the bottom of the road), and are wired along both surfaces of the plate-shaped deformation transmitting member 33 to be bonded and fixed. Are integrated. And
The optical fiber sensor 32 is folded at a point away from the shaft 24 and is pulled out at a plurality of places along the optical fiber 4 wired toward the shaft 24, so that the structures 21 A, 21
It is provided continuously at a plurality of locations in the extending direction of the road B.

The optical fibers 4 constituting the optical fiber sensors 2, 2a, 32 are given an initial strain, and any of the optical fiber sensors 2, 2a, 32 detects expansion / contraction strain of the optical fiber 4, that is, A change in the amount of strain in the longitudinal direction can be detected. This makes it possible to detect the deformation of the structures 21A and 21B in any direction of expansion and contraction of the optical fiber 4 by an optical test of the optical fiber 4. It is appropriate that the end of each optical fiber 4 farthest from the optical pulse tester 23 be subjected to anti-reflection processing.

For example, when the deformation of the structures 21A and 21B in the extending direction, for example, the deformation such as the expansion and contraction in the axial direction locally occurs in a part of the road of the structures 21A and 21B, the structure 21A The optical fibers 4 of the optical fiber sensors 2 and 2a located in the deformed portions of the
The optical fiber 4 is deformed integrally with A and 21B, so that the optical fiber 4 is given a stretching strain. Here, the optical fiber sensors 2, 2a
Optical test using the optical pulse tester 23 for the optical fiber 4 constituting the optical fiber 4 (specifically, incidence of test light on the internal optical fiber 9 and observation of return light), and observation of Brillouin scattered light. Thus, the occurrence of deformation in the axial direction of the structures 21A and 21B can be detected. Further, the position of the deformed portion of the structure can be grasped from the return time of the return light.

On the other hand, deformation in the direction perpendicular to the direction in which the structures 21A and 21B extend. In FIG.
The deformation in the sectional direction of the road A, 21B can be detected by an optical test of the optical fiber 4 constituting the optical fiber sensor 32. In FIGS. 9A and 9B, the deformation transmitting member 33 is installed between the walls on the both sides in the diameter direction (specifically, between the upper and lower walls) in the structures 21A and 21B which are the roads. When deformations such that the walls on both sides are separated or approach each other act on the structures 21A and 21B, the structures 21A and 21B
The deformation transmitting member 33 is deformed in the longitudinal direction corresponding to the deformation distortion of the deformation transmitting member 21B, and the optical fiber 4 integrated with the deformation transmitting member 33 is expanded and contracted. Therefore, the optical fiber 4 constituting the optical fiber sensor 32
By observing the Brillouin scattered light caused by the stretching strain of the optical fiber 4 by the optical test of
Deformation in a direction substantially perpendicular to the extending direction of B can be detected and monitored. For example, the structure 21A which is a road,
The depression of the bottom 21b due to the subsidence of the ground under 21B can be detected by the optical fiber sensor 32. Further, the optical fiber sensor 32 can detect various deformations of the structures 21A and 21B as long as the deformation transmitting member 33 deforms in the longitudinal direction.

As shown in FIG. 8, in this deformation detection system 20, the optical fiber sensors 2 and 2a for detecting deformation of the structures 21A and 21B in the extending direction, and the structures 21A and 21B,
Since the optical fiber sensor 32 for detecting the deformation in the direction substantially perpendicular to the extending direction of the optical fiber 1B is constituted by one optical fiber 4, the Brillouin scattered light obtained by the optical test of the optical fiber 4 is used as an observation result. , Structures 21A, 21
B deformation can be detected and monitored over a wide range.

As shown in FIGS. 10A and 10B, in the deformation detection system 20, an optical fiber sensor 35 in which the deformation transmitting member 3 and the optical fiber 4 are fixed is also provided in the shaft 24. Since it is assembled, the deformation of the shaft 24 can be detected and monitored. The deformation transmitting member 3
The optical fiber sensor in which the optical fiber 4 is fixed to the structure can be easily assembled to various structures.
It can be easily installed inside, inside and outside the monitoring station 22, and the optical test of one optical fiber 4 can easily detect and monitor the deformation of a plurality of structures such as shafts and tunnels.

The optical fiber sensors 2 and 2a are very simple in construction and easy to construct, so that the assembly and installation of the structure over a wide range can be performed efficiently in a short time. Moreover, since it is not necessary to lay a power supply or a separate signal line for data transmission, installation inside a narrow structure such as a road does not narrow the internal space of the structure. Also, there is no obstacle to drawing in the communication optical fiber cable or electric cable to the road after the installation of the optical fiber sensors 2 and 2a.

If the Fresnel reflected light is detected when the test light enters the optical fiber 4 from the optical pulse tester 23, a disconnection such as breakage of the optical fiber 4 is detected. In this case, since the broken position of the optical fiber 4 can be roughly specified by the elapsed time from the entrance of the test light to the reception of the Fresnel reflected light, the cut portion of the optical fiber 4 that has been erroneously cut due to, for example, construction can be easily found. , Repair work time and the like can be reduced. As described above, according to the deformation detection system 20, by performing the optical test of the optical fiber 4 by the optical pulse tester 23 as needed, it is possible to monitor the failure related to the optical transmission system.

FIGS. 11 and 12 are sectional views showing examples of the structure of the optical fiber 4. The optical fiber 4 shown in FIG.
In order to distinguish them from each other, reference numeral 4a (4) is used for the optical fiber shown in FIG. 11, and reference numeral 4b is used for the optical fiber shown in FIG.
(4), but in the following description, the optical fiber 4
a and the optical fiber 4b.

In the optical fiber 4a shown in FIG. 11, a bonding material 42 made of resin foam or the like is provided in a layer on one surface of a resin film 41 made of polyimide or the like.
2 is a long sheet-shaped optical fiber cable in which a multi-core tape-shaped optical fiber 43 (hereinafter referred to as an internal optical fiber 43; in FIG. 11, a four-core optical fiber ribbon) is embedded and fixed. In FIG. 11, reference numeral 44 denotes release paper. The optical fiber 4a is superior to the optical fiber 4 shown in FIG. 4 in mechanical properties such as lateral pressure characteristics (the internal optical fiber 43 is less likely to be deformed by the lateral pressure), tensile strength, and scratch resistance. I have. Further, since the carbon fiber coated optical fiber tape is used as the internal optical fiber 43, the durability can be improved and the strain sensing characteristics can be maintained for a long time. Further, the detection of the strain in the longitudinal direction of the optical fiber 4a can be performed by performing an optical test on any one of the plurality of optical fibers built in the internal optical fiber 43.
Even if the optical fiber initially used as the object of the optical test can no longer be used due to breakage or the like, the object of the optical test may be changed to another optical fiber. As a result, the same optical fiber 4a can be used for detecting the deformation of the structure for a long period of time, and the life of the optical fiber sensor constituted by using this optical fiber 4a can be extended.

In the optical fiber 4b shown in FIG. 12, a bonding material 52 made of a resin foam or the like is provided in a layer on one surface of a resin film 51 made of a polyimide or the like.
An optical fiber 53 (hereinafter referred to as an internal optical fiber 53)
And a temperature correcting optical fiber 54 embedded and fixed. In FIG. 12, reference numeral 55 denotes release paper. As the internal optical fiber 53,
Optical fiber single core wire and the like are used, especially,
From the viewpoint of extending the life, it is preferable to use a carbon-coated optical fiber or the like as the optical fiber core. The temperature compensating optical fiber 54 is made of a protective tube 54 made of stainless steel or the like.
The optical fiber 54b (the optical fiber for temperature correction) is loosely housed in a, and even if the optical fiber 4b is subjected to the elongation strain, the elongation distortion does not act on the optical fiber 54b for the temperature correction. The optical characteristics of the temperature compensating optical fiber 54b are not affected at all. Even if stretching strain is given to the internal optical fiber 53 giving initial strain,
It goes without saying that the optical characteristics of the temperature correcting optical fiber 54b are not affected at all. The temperature compensating optical fiber 5
Also as 4b, it is more preferable to use an optical fiber core made of a carbon-coated optical fiber from the viewpoint of extending the durability.

The frequency shift amount of the Brillouin scattered light with respect to the incident light is about 1M even when the optical fiber has no distortion.
Since it has a temperature dependency of about Hz / ° C., it is necessary to correct measurement data when a large temperature change over several tens of degrees C. occurs. The optical fiber is used for
For example, the sun may be heated to several tens of degrees Celsius or more than normal temperature due to the sunshine or the geothermal heat of the volcanic zone. For more accurate monitoring, temperature correction of Brillouin scattered light measurement data is required. Is essential. In consideration of this, in the optical fiber 4b, a temperature correcting optical fiber core wire 54 is juxtaposed separately from the internal optical fiber 53 to which elongation strain is applied. That is, the optical test data of the temperature correcting optical fiber 54b to which no distortion in the longitudinal direction is given is:
Since only the influence of the temperature change is reflected, the optical test data of the internal optical fiber 53 for distortion detection can be corrected by using the optical test data of the optical fiber 54b for temperature correction. From the optical test data of the temperature compensating optical fiber 54b, the shift amount of the frequency of the Brillouin scattered light with respect to the incident light due to the temperature change can be grasped. The grasped frequency shift amount is observed by the optical test of the internal optical fiber 53. By subtracting from the calculated shift amount of the frequency of the Brillouin scattered light, the shift amount of the Brillouin scattered light frequency caused by the expansion and contraction of the internal optical fiber 53 can be grasped.

At the end of the optical fiber 4b farther from the optical pulse tester 23 side, an optical fiber 53 for distortion detection and an optical fiber 54b for temperature correction are connected to form a loop. An optical test is performed on both optical fibers 53 and 54b by incidence of test light from one of the fibers 53 and 54b,
Observing Brillouin scattered light also enables temperature correction of the measured data. In this case, the optical fiber 53
Although the data of the Brillouin scattered light due to the initial strain can be obtained from the optical test result of the above, the detection data of the Brillouin scattered light can hardly be obtained from the optical test result of the optical fiber 54b for temperature correction. Each optical fiber 53,5 from the measurement data obtained by one optical test
It is possible to determine the measurement data of 4b and grasp them individually. Then, as described above, the shift amount due to the temperature change of the frequency with respect to the incident light of the Brillouin scattered light, which is grasped from the optical test data of the temperature correcting optical fiber 54b,
By subtracting from the shift amount of the frequency of the Brillouin scattered light observed by the optical test of the internal optical fiber 53, the shift amount of the frequency of the Brillouin scattered light due to the stretching strain of the internal optical fiber 53 can be grasped. According to this temperature correction method, both optical fibers 53 and 54b of the optical fiber 53 for distortion detection and the optical fiber 54b for temperature correction can be optically tested by one optical test. In the case of monitoring the occurrence of distortion while switching the optical fibers of the sensor to the optical pulse tester, the number of switching of the optical fibers to the optical pulse tester can be reduced, which simplifies the monitoring work, It is possible to shorten the optical test interval (time) of the optical fiber of the fiber sensor. In addition, it is also possible to easily identify the connection point by giving a particularly large elongation strain to the optical fiber connecting the two optical fibers 53 and 54b, thereby making it possible to determine the connection point. It becomes even easier to grasp the discrimination of the optical test results individually.

The method of correcting the temperature of the measured data is not limited to the above-described method.
It is also possible to adopt a method of correcting measurement data of Brillouin scattered light from data obtained by receiving and observing backscattered light of Raman scattered light of the incident light to 4b with an optical pulse tester. In addition,
Since it is necessary to maintain the distortion-free optical fiber 54b, for example, the temperature-correcting optical fiber 5b is placed in a termination box installed at an appropriate position in the middle of the optical fiber 4b.
When the optical fiber 4b is stretched and strained, the elongate strain is applied to the internal optical fiber 53 for detecting Brillouin scattered light, while the temperature correcting optical fiber 54b is stretched when the optical fiber 4b is stretched. A configuration in which the length is drawn into the optical fiber 4b (specifically, the protection tube 54a) to maintain a distortion-free state can be adopted.

FIG. 13 shows a method for repairing the optical fiber sensor 2. For example, if the optical fiber 4 is damaged due to damage by rats, careless contact of workers passing through the road, etc., the existing optical fiber 4
The optical fiber 4n (hereinafter referred to as “optical fiber 4n” for the sake of distinction) can be easily newly provided next to the optical fiber 4n, and the optical fiber sensor 2 can be easily repaired. In FIG. 7B, a plurality of optical fibers 4 and 4n (FIG.
(B), a deformation transmitting member 3 having an optical fiber fixing region 3a having a width dimension T capable of fixing two in parallel is adopted, and an optical fiber 4 first fixed to the deformation transmitting member 3 is:
The optical fiber fixing region 3a extending toward the center in the width direction of the deformation transmitting member 3 is fixed to one side in the width direction (direction perpendicular to the longitudinal direction of the deformation transmitting member 3), and is fixed to the optical fiber fixing region 3a. On the opposite side in the width direction, a new optical fiber 4
An area where n can be fixed is secured. Therefore, by fixing the newly provided optical fiber 4n in the remaining area of the optical fiber fixing region 3, the new optical fiber 4n can be easily provided. The optical fiber fixing region 3a is a region between the tack fixing portions 3b secured on both sides in the width direction of the deformation transmitting member 3, and if the optical fibers 4, 4n are fixed in the range of the optical fiber fixing region 3a. The optical fibers 4 and 4n do not buffer the studs 6 driven into a plurality of places of the stud fixing portion 3b. In the optical fiber sensor 32 as well, the deformation transmitting member 3
By securing an area in which a plurality of optical fibers 4 and 4n can be fixed in parallel to 3, it becomes possible to easily install new optical fibers 4 and 4n similar to the deformation transmitting member 3. Thereby, repair workability can be improved.

It should be noted that the present invention is not limited to the configuration exemplified in the above embodiment, and various modifications are possible. For example,
The method of assembling the optical fiber sensor according to claims 1 and 2 and the structure of the optical fiber applied to the optical fiber sensor according to claim 3 are not limited to those illustrated in FIGS. 4, 11, and 12. Instead of the bonding material 8 having the function of absorbing unevenness of the deformation transmitting member due to plastic deformation, an adhesive layer having only an adhesive function can be applied. FIGS. 4, 11 and 12 show optical fibers applicable to the present invention.
However, the present invention is not limited to the sheet-type optical fiber cable as exemplified in the above, and may be, for example, a single-core or multi-core optical fiber cable. However, in the case of the sheet-type optical fiber cable illustrated in FIGS. 4, 11 and 12, securing of adhesive force to the deformation transmitting member, improvement of workability, securing of durability, contact of workers and animals, etc. This is advantageous in terms of preventing erroneous detection due to, for example,

[0049]

According to the method of assembling the optical fiber sensor of the present invention, the optical fiber is attached to the deformation transmitting member laid on the structure, so that the optical fiber is structured via the deformation transmitting member. Since it is provided so that it can be attached to the object, it is possible to reduce the trouble of processing the surface of the structure,
The optical fiber can be efficiently fixed to the structure, and an excellent effect that the optical fiber sensor can be assembled in a short time can be obtained.

In the method for assembling an optical fiber sensor according to the second aspect, a tape-shaped deformation transmitting member is fixed to the structure, and the optical fiber is fixed to the deformation transmitting member. It can be laid and fixed on the structure as it is laid, and the work of installing the deformation transmitting member over a wide area of the structure can be performed efficiently, and the optical fiber sensor can be assembled efficiently in a short time. It has an excellent effect of being able to do it.

According to the optical fiber sensor of the third aspect, the deformation in the direction perpendicular to the extending direction of the structure can be efficiently detected and monitored. In addition, since the optical fiber sensor is assembled so that the optical fiber is attached to the deformation transmitting member installed between the structures, the optical fiber sensor can be assembled at any place where the deformation transmitting member can be installed, and the shape of the structure can be adjusted. An excellent effect is obtained in that the deformation of the structure can be detected and monitored in a wide range.

[Brief description of the drawings]

FIG. 1 is a view showing an example of an optical fiber sensor assembled into a structure by an optical fiber sensor assembling method according to the present invention, wherein (a) is a cross section showing a cross-sectional structure perpendicular to the axial direction of a road. FIG. 3B is a cross-sectional view in the direction along the axial direction of the road.

FIG. 2 is a cross-sectional view showing a ceiling of a structure in which the optical fiber sensor of FIG. 1 is assembled.

FIG. 3 is a perspective view showing a deformation transmitting member of the optical fiber sensor of FIG. 1;

FIG. 4 is a sectional view showing an example of a sectional structure of an optical fiber applied to the optical fiber sensor of FIG.

5A and 5B are diagrams illustrating a work of fixing a deformation transmitting member to a structure, and FIG. 5A illustrates a state in which a tape-shaped deformation transmitting member is pressed against a structure (a ceiling of a road) by a roller. FIG. 3B is a bottom view of FIG.

6A and 6B are diagrams showing a fixing operation of the deformation transmitting member to the structure, wherein FIG. 6A is a diagram showing a state before driving of a tack for fixing the deformation transmitting member to the structure, and FIG. It is a figure which shows the rivet driven into the member, and the rivet driving hole into which the rivet is driven.

FIGS. 7A and 7B are diagrams illustrating an operation of fixing an optical fiber to a deformation transmitting member fixed to a structure, and FIG. 7A illustrates a state where the optical fiber is pressed against the deformation transmitting member using a roller; (B) is a diagram showing a state where the optical fiber is fixed to the deformation transmitting member.

FIG. 8 is an overall view showing a deformation detection system.

FIGS. 9A and 9B are diagrams showing an installation state of an optical fiber sensor for detecting deformation in a direction substantially perpendicular to an extending direction of a structure (a road), and FIG. 9A shows a cross section perpendicular to the extending direction. FIG. 3B is a cross-sectional view in a direction along the extending direction.

FIG. 10 is a perspective view showing a state in which optical fibers are laid in a shaft and an optical fiber sensor assembled in the shaft.

FIG. 11 is a cross-sectional view showing a cross-sectional structure of an optical fiber applied to the present invention, showing an optical fiber provided with a multi-core optical fiber tape.

FIG. 12 is a cross-sectional view showing a cross-sectional structure of an optical fiber applied to the present invention, showing an optical fiber provided with a temperature correcting optical fiber.

13A and 13B are diagrams showing a method for repairing an optical fiber sensor assembled by the method for assembling an optical fiber sensor according to the present invention, wherein FIG. 13A shows a state in which a new optical fiber is pressed against a structure by a roller. (B) is a diagram showing a fixed position of a newly provided optical fiber in the deformation transmitting member.

[Explanation of symbols]

1 ... Structure (toll road), 1a ... Structure (ceiling), 1b
... structure (bottom), 2, 2a ... optical fiber sensor, 3 ...
Deformation transmission member, 4, 4a, 4b, 4n: optical fiber (optical fiber cable), 21A, 21B: structure (toll road), 21a: structure (tower ceiling), 21b: structure (tower bottom) ), 24: structure (vertical shaft), 32: optical fiber sensor, 33: deformation transmitting member (primary plate).

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yoshikazu Nomura 1440 Mutsuzaki, Sakura City, Chiba Prefecture Fujikura Sakura Office F-term (reference) 2F065 AA65 CC00 CC40 FF41 UU07 2F076 BB09 BD06 2F103 CA07 GA15 2H038 AA05 CA63

Claims (3)

[Claims] 1. Structures (1, 1a, 21A, 21B, 2
An optical fiber sensor (2,
2a), wherein a flexible deformation transmitting member (3) is laid on the structure and fixed, and the optical fibers (4, 4a, 4
b, 4n) to attach the optical fiber to a structure via the deformation transmitting member. 2. The method for assembling an optical fiber sensor according to claim 1, wherein a tape-shaped deformation transmitting member is fixed to the structure, and the optical fiber is fixed to the deformation transmitting member. 3. An optical fiber sensor for detecting deformation of a structure by light, wherein the deformation is provided substantially perpendicular to the extending direction of the structure (21A, 21B, 21a, 21b). A transmission member (33) is bridged between the structure and a structure located at a position separated from the structure and fixed to both structures, and an optical fiber (4) is attached to the deformation transmission member. , 4a, 4b) provided so as to be attached to the optical fiber sensor (32).