JP3417850B2 - Method for detecting displacement of concrete structure and sensor used therefor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a displacement (strain) of a non-planar portion in a concrete structure, for example, a road for accommodating a telephone wire, a displacement in the inner space, and a sensor used therefor. .

[0002]

2. Description of the Related Art Conventionally, as a method of detecting various displacements in a concrete structure, an optical fiber is attached to the concrete structure and the strain generated in the optical fiber is measured by a known optical strain measuring machine (OTDR). There was a method to detect.

An optical strain measuring device is a backscattered light (light returning in a direction opposite to the traveling direction of light) generated when light propagates in an optical fiber, and has a magnitude of distortion of the optical fiber. Utilizing light (Brillouin scattered light) whose optical frequency changes in proportion, an optical pulse of a predetermined frequency is incident from one end of the optical fiber, and the change of the optical frequency in the Brillouin scattered light generated by this optical pulse is By measuring the generation position at one end of the optical fiber with time,
This is a device for measuring the strain in the length direction of an optical fiber.

FIG. 1 shows an example of a conventional displacement detection method using an optical strain measuring device. An optical fiber 1 is attached to a structure 2 so as to be integrated with the optical fiber, and one end of the optical fiber is measured. The displacement of the structure 2 is detected by connecting to the machine 3 and measuring the strain generated in the optical fiber 1 by the optical strain measuring machine 3.

FIG. 2 shows another example of the conventional displacement detection method using an optical strain measuring device, here, a method for detecting the dimension (inner displacement) inside a hollow structure.
The rod-shaped elastic body 5 is fixed inside the structure 4 so that both ends thereof contact the upper and lower inner walls of the structure 4, and the optical fiber 1 is attached to the elastic body 5 so as to be integrated with the elastic body 5. , By connecting one end thereof to the optical strain measuring device 3, the displacement 6 generated in the structure 4 is transmitted to the displacement of the elastic body 5 as shown in FIG. The optical strain measuring device 3 measures and detects.

[0006]

By the way, in the case of accurately measuring the strain generated in the structure by the method of FIG. 1,
In order to prevent the optical fiber 1 from being loosened, the optical fiber 1 must be attached with a certain amount of tension applied. It is easy to attach the optical fiber 1 to the planar portion of the structure 2 as shown in FIG. 1 in a state where tension is applied, but the structure 7 having the hollow circular cross section shown in FIG. Regarding a non-planar portion such as the inside, it is difficult to attach the optical fiber 1 in a state where tension is applied, and there is a problem that strain measurement is likely to be inaccurate.

The method shown in FIG. 2 is based on the assumption that the rod-shaped elastic body 5 is elastically deformed. In reality, however, buckling 8 or the like occurs and the elastic body 5 is structured as shown in FIG. There is a problem that the displacement of the object 4 cannot be accurately transmitted to the optical fiber 1 and accurate measurement cannot be performed.

An object of the present invention is to provide a method capable of accurately detecting displacement (strain) of a non-planar portion of a concrete structure.

Another object of the present invention is to provide a method for accurately detecting the inner-air displacement of a hollow concrete structure and a sensor used for the method.

[0010]

According to the present invention, in order to achieve the above object, in a displacement detecting method of a concrete structure for detecting displacement of a non-planar portion of the concrete structure, one optical fiber is connected to the concrete structure. The non-planar part of the optical fiber is attached so that the attached parts to be attached under tension and the extra length part that is not in contact are arranged alternately, and the strain generated in the optical fiber is measured by an optical strain measuring machine. The feature is that the displacement is detected from this.

According to the above construction, it becomes possible to attach the optical fiber even in a non-planar portion of the structure so as not to cause slack, and by measuring the strain produced in the optical fiber, the individual attachments can be made. The strain generated in the portion can be measured, and the displacement (strain) of the non-planar portion of the structure can be detected from this.

Further, at this time, if the respective attachment portions are apparently arranged continuously with respect to the non-planar portion of the structure, the displacement in the entire non-planar portion can be detected as it is.

Further, in order to achieve the above object, the present invention provides a method for detecting displacement of a concrete structure for detecting inner-air displacement of a hollow concrete structure, wherein two rod-shaped rigid bodies and two rigid bodies are used. A sensor consisting of an elastic body sandwiched between the ends of the elastic body and an optical fiber wrapped around the elastic body, and the distance between the ends of the two rigid bodies is displaced according to the in-air displacement of the concrete structure. Place it like
It is characterized in that the strain generated in the optical fiber is measured by an optical strain measuring machine and the displacement is detected from this.

According to the above construction, the displacement in the air of the structure is converted into the radial displacement of the elastic body of the sensor, and thereby the optical fiber wound around the elastic body is expanded and contracted to measure the strain. The internal air displacement of the structure can be accurately detected.

Further, in the present invention, in order to achieve the above object, in a displacement detecting method of a concrete structure for detecting an inner-air displacement of a hollow concrete structure, the first and second slidably combined mutually. Member, and a first optical fiber fixed to the first and second parts on the first and second members, the distance between which narrows when the two members come close to each other and widens when the two members separate from each other; And a second optical fiber fixed to the third and fourth parts, the distance between which widens when the two members slide close to each other on the second member and narrows when the two members move away from each other. The second member is arranged so as to slide in accordance with the displacement of the concrete structure in the air, and the strain generated in the first and second optical fibers is measured by an optical strain measuring machine. Characterized in that it out.

According to the above structure, since the internal air displacement of the structure can be transmitted as the extension of either the first or second optical fiber of the sensor, the internal air displacement of the structure can be accurately detected.

[0017]

FIG. 5 shows a first embodiment of the present invention, which is a method for detecting displacement (strain) of a non-planar portion of a concrete structure, in which 11 is a structure. Of the non-planar part (however, it is shown as a plane in the drawing), 12 is one optical fiber.

The optical fiber 12 is attached to the non-planar portion 11 in a state in which tension is applied by an adhesive or the like to the attaching portions 12-1, 12-2, 12-3, 12-4, 12.
-5, 12-6 (shown by thick lines in the figure) and the extra length portions 12-7, 12-8, 12-9, 12-10, which are not in contact with each other.
12-11 and 12-11 are installed so as to be alternately arranged, and one end thereof is connected to an optical strain measuring device (not shown).

Here, each pasting portion 12-1 to 12-6.
Is set to a length (usually 10 to 30 cm (actually, it varies depending on the curvature of the non-planar portion)) such that tension is applied even to the non-planar portion, and each extra length portion 12-7.
The lengths 12 to 11 are set to such a length that each attached portion can be separated from the other attached portions.

Due to such a structure, it is possible to attach the optical fiber even in the non-planar portion of the structure so as not to cause slack.
By measuring the strain generated in No. 2, the strain generated in each attached portion can be measured, and the displacement (strain) of the non-planar portion of the structure can be detected from this.

At this time, each extra length portion 12-7 to 12-11
Is almost unaffected by the displacement of the structure and causes no strain, so the strains corresponding to these sites are not measured,
It can be ignored in the data.

Further, the sticking portions 12-1 to 12-6 are apparently arranged continuously with respect to the non-planar portion 11 of the structure, that is, the end portions of the sticking portions adjacent to each other are not to be detected. If they are arranged so as to coincide with each other in the length direction of the plane portion, the displacement in the entire non-plane portion can be detected as it is.

FIG. 6 shows a second embodiment of the present invention, which is a method for detecting the inner-air displacement of a hollow concrete structure and a sensor used therefor. In the figure, 3 is an optical strain measurement. A machine, 4 is a hollow structure, and 20 is a sensor.

As shown in FIG. 7, the sensor 20 comprises two rod-shaped rigid bodies 21 and 22 made of steel or the like and rigid bodies 21 and 22.
A cylindrical elastic body 23 made of rubber or the like sandwiched between the ends of the elastic body 23 and an optical fiber 24 wound in the circumferential direction of the elastic body 23. The optical fiber 24 is arranged in contact with the upper and lower inner walls of the structure 4, and one end of the optical fiber 24 is connected to the optical strain measuring device 3.

Hereinafter, the method of detecting the vertical displacement of the structure will be described.

In FIG. 6A, the vertical displacement of the structure 4, for example, compressive deformation, is transmitted to the sensor 20 as compressive stress. That is, as shown in FIG. 6B, due to the stress received from the structure 4, the rigid bodies 21 and 22 are displaced so that the distance (distance) between their one ends becomes small, and the compressive stress is transmitted to the elastic body 23. . Due to the compressive stress received, the elastic body 23 is deformed in the radial direction so as to have a large cross-sectional area, whereby stress is applied to the optical fiber 24 in the tensile direction and strain is generated. The strain generated in the optical fiber 24 is measured by the optical strain measuring device 3, and the compressive deformation of the structure 4 can be detected by analyzing the strain.

FIG. 8 illustrates how the internal air displacement of a structure is converted into radial displacement of an elastic body and detected. The height of the elastic body 23 when the displacement of the structure is 0 is h,
The radius is r, and the structure is displaced by Δh (compressive displacement here).
When the radius of the elastic body 23 is R,
Is elastically deformed and there is no volume change, then πr ² h = πR ² (h−Δh) ∴R = {h / (h−Δh)} ^1/2 · r. At this time, assuming that the amount of change in strain of the optical fiber measured by the optical strain measuring device is Δε, Δε = (R−r) / r = {h / (h−Δh)} ^1/2 −1 ∴ Δh = It can be obtained as {1-1 / (Δε + 1) ² } h (In reality, since complete elastic deformation cannot be expected, the relation between the strain change amount Δε and the displacement Δh is obtained in advance and tabulated. Is also good).

When the structure 4 is stretched and deformed, the elastic body 23 is deformed in the radial direction so that the cross-sectional area becomes small, and the optical fiber 24 is subjected to a compressive stress.
In this case as well, detection can be performed in the same manner as described above, and detection can be performed by aligning the direction of the sensor 20 even if the displacement direction is other than vertical.

FIG. 9 shows a third embodiment of the present invention, a method for detecting the inner-air displacement of a hollow concrete structure, and another example of a sensor used therefor.

In FIG. 9, reference numeral 30 denotes a sensor, which is a first and a second member slidably combined with each other,
Here, the outer pipe 31 and the inner pipe 32, and the outer pipe 31 and the inner pipe 3
2, the first and second optical fibers 33 and 34 fixed as will be described later, and the outer pipe 31 and the inner pipe 32 are the spacing adjusting rods 41 and 42 made of an iron pipe or the like and the pad made of an iron plate or an anchor or the like. It is arranged so as to slide on the upper and lower inner walls 45 of the structure via the plates 43 and 44 according to the displacement thereof.

The first optical fiber 33 slides on the outer tube 31 and the inner tube 32 so that the distance between them narrows when they come close to each other and widens when they move away from each other.
1a and 32a are fixed, and the second optical fibers 34 slide on each other on the outer tube 31 and the inner tube 32, and when they come close to each other, the distance between them widens, and when the second optical fibers 34 move away from each other, the distance narrows. It is fixed to 32b. Also,
These first and second optical fibers 33 and 34 are composed of two parts separated by a distance equal to or greater than the distance resolution of the optical strain measuring instrument in one optical fiber, and one end thereof is not shown. An optical strain measuring instrument is connected (it is also possible to separately connect two optical strain measuring instruments as separate optical fibers).

When the structure is stretched and deformed in the vertical direction, that is, when the space between the inner walls 45 is widened, the outer pipe 31 moves upward and the inner pipe 32 moves downward. The optical fiber 33 extends (tensiles), and the second optical fiber 34
Shrinks (compresses). On the other hand, the structure is compressed and deformed in the vertical direction,
That is, when the space between the inner walls 45 becomes narrow, the outer pipe 31 moves downward,
Also, the inner pipe 32 moves upward, and at this time, the first
The optical fiber 33 of the second optical fiber 3
4 stretches (tensile).

Therefore, by measuring the strains of both optical fibers with an optical strain measuring device and measuring which optical fiber is stretched and the stretch, it is possible to detect whether the fiber is stretched or compressed. The amount of displacement can be detected from the strain in the extension direction without causing slack in the optical fiber.

As described above, the displacement detection using the optical strain measuring device can be measured as the strain corresponding to the distance from one end of the optical fiber to the optical fiber. Therefore, various displacements of the structure can be continuously detected by one optical fiber.

FIG. 10 shows a fourth embodiment of the present invention. One end of an optical fiber 50, one end of which is connected to the optical strain measuring device 3, is provided with respect to a tunnel-shaped structure 60. Direction upper part 61 is continuously laid under tension (51), and the inner surface 62 in the circumferential direction is alternately arranged with the sticking parts and the extra length parts as described in the first embodiment. (52), and continuously laying (53) with tension applied to the lower portion 63 in the longitudinal direction.
It is arranged so that the sensors (54, 55) described in the second (or third) embodiment are formed at two locations 64, 65 in the vertical direction.

FIG. 11 shows an example of the measurement results in the embodiment of FIG. 10, in which the broken line shows the initial strain and the solid line shows the strain after displacement. Further, each reference numeral in the drawing is the same as that in FIG.
Corresponding to each part of the optical fiber inside, 5 each
The portion 1 is elongated in the longitudinal direction, the portion 52 is vertically compressed, contracted in the upper and lower portions, and elongated in the left and right portions to be flattened (however, the data of the extra length portion is omitted). , 53 is longitudinally contracted, 54
It is shown that the state of being contracted in the vertical direction is detected in the portion of, and the state of being extended in the vertical direction is detected in the portion of 55.

[0037]

As described above, according to the present invention,
A single optical fiber is attached to a non-planar portion of a structure by alternately arranging a pasting portion and a surplus length portion to be attached in a state in which tension is applied, thereby causing optical distortion in a non-planar section of the structure. Can be accurately detected using a measuring machine.

Further, according to the present invention, the internal displacement of the structure is converted into the displacement of the elastic body in the radial direction and the sensor for expanding and contracting the optical fiber is used, or the internal displacement of the structure is reduced. By using the sensor that transmits as an extension of either the first or the second optical fiber, the inner-air displacement of the structure can be accurately detected by using the optical strain measuring machine.

Further, according to the present invention, since various kinds of displacements of the structure can be measured as strains of the optical fiber from one end of the optical fiber, the displacement of an arbitrary detection position of the structure can be detected by one optical fiber. Fiber allows continuous measurement, and
Since it is only necessary to install a sensor that combines an optical fiber or a simple member with it at the detection position, it is possible to detect without power equipment etc. near the detection position,
Even if flammable gas or the like is generated near the detection position, there is no danger of causing an accident, and further, the detection accuracy can be improved according to the improvement of the measurement accuracy of the optical distortion measuring device.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of a conventional displacement detection method using an optical distortion measuring device.

FIG. 2 is a configuration diagram showing another example of a conventional displacement detection method using an optical distortion measuring device.

FIG. 3 is an explanatory diagram of problems in the method of FIG.

FIG. 4 is an explanatory diagram of problems in the method of FIG.

FIG. 5 is a configuration diagram showing a first embodiment of the present invention.

FIG. 6 is a configuration diagram showing a second embodiment of the present invention.

7 is a configuration diagram showing details of a sensor in FIG.

FIG. 8 is an explanatory diagram of a relationship between displacement of a structure and deformation of an elastic body.

FIG. 9 is a configuration diagram showing a third embodiment of the present invention.

FIG. 10 is a configuration diagram showing a fourth embodiment of the present invention.

FIG. 11 is a diagram showing an example of a strain measurement result in the fourth embodiment.

[Explanation of symbols]

3: Optical strain measuring device, 4, 50: Structure, 11: Non-planar part of structure, 12, 24, 33, 34, 60: Optical fiber, 12-1 to 12-6: Sticking part, 12-7 ~ 12
-11: extra length part, 20, 30: sensor, 21, 22: rigid body, 23: elastic body, 31: outer tube, 32: inner tube.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuo Okamine 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Kazuomi Koga 3-chome, Nishishinjuku, Shinjuku-ku, Tokyo 19-2 Nihon Telegraph and Telephone Corporation (72) Inventor Tetsuya Uehara 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Nihon Telegraph and Telephone Corporation (56) Reference JP-A-11-351983 (JP , A) JP-A-11-258356 (JP, A) JP-A-11-230840 (JP, A) JP-A-62-220823 (JP, A) JP-A-61-258131 (JP, A) JP-A 57-122304 (JP, A) Actual development Sho 63-145114 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01B 11/16 G01D 21/00 G01L 1/24

Claims (6)

(57) [Claims] 1. A displacement detection method for a concrete structure for detecting displacement of a non-planar portion of the concrete structure, wherein one optical fiber is attached to the non-planar portion of the concrete structure under tension. A concrete structure characterized by being attached so that the sticking portions and the extra length portions that do not come into contact are arranged alternately, measuring the strain generated in the optical fiber with an optical strain measuring machine, and detecting the displacement from this. Displacement detection method for objects. 2. The method for detecting displacement of a concrete structure according to claim 1, wherein the pasting portion is arranged apparently continuously with respect to the non-planar portion of the concrete structure. 3. A displacement detection method for a concrete structure for detecting the inner-air displacement of a hollow concrete structure, comprising: two rod-shaped rigid bodies; and an elastic body sandwiched between one ends of the two rigid bodies. , A sensor consisting of an optical fiber wound around an elastic body is arranged so that the distance between the ends of the two rigid bodies is displaced according to the in-air displacement of the concrete structure. A method for detecting the displacement of a concrete structure, characterized in that the measured strain is measured by an optical strain measuring machine and the displacement is detected from the measured strain. 4. A concrete structure characterized by comprising two rod-shaped rigid bodies, an elastic body sandwiched between one ends of the two rigid bodies, and an optical fiber wound around the elastic body. Displacement detection sensor. 5. A method for detecting displacement of a concrete structure for detecting inner-air displacement of a hollow concrete structure, comprising first and second members slidably combined with each other, and first and second members. A first optical fiber fixed to the first and second portions, where the space narrows when the two slide close to each other, and widens when the two move away from each other;
A sensor comprising a second optical fiber fixed to third and fourth portions, the distance between which spreads when the two members slide and approach each other on the first and second members, and narrows when the two members separate from each other, And the second member are arranged so as to slide in accordance with the displacement of the concrete structure in the air, and the strain generated in the first and second optical fibers is measured by an optical strain measuring machine, and the displacement is detected from this. A method for detecting the displacement of a concrete structure, characterized by: 6. A first member and a second member which are slidably combined with each other, and a first member and a second member on the first member and the second member, which are slidably close to each other and have a narrower interval, and when separated from each other, the interval is wider. The first optical fiber fixed to the second portion and the first and second members are fixed to the third and fourth portions on the first and second members, where the distance is widened when they come close to each other and narrowed when they are separated from each other. Displacement detection sensor for a concrete structure, characterized by comprising: