JP2000298009A - Method for arranging optical fiber for measuring deformation of structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To build a method for quickly installing an optical fiber by setting a bendable pipe along a surface of a structure, inserting the optical fiber inside the pipe and uniting the optical fiber and the pipe. SOLUTION: A pipe 2 is arranged while curved to trace an inner surface of a tunnel 1. The pipe 2 is bendable and can be arranged to trace the surface while being freely bent even if the surface of the structure is not flat. After the pipe 2 is arranged by a desired length, an optical fiber 3 is inserted in the pipe 2. As a method for inserting the optical fiber 3, for example, an air flow is sent by blowing the air into the pipe 2 and the optical fiber 3 is inserted in the pipe 2 by this air flow. Although it is necessary to unite the optical fiber 3 and the pipe 2 after the optical fiber is inserted to the pipe 2, a method used for the uniting is, e.g. forming the pipe 2 of a thermally shrinkable synthetic resin, applying heat by pouring hot water to the pipe 2 after inserting the optical fiber or by the like manner and, thermally shrinking the pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for arranging an optical fiber for measuring deformation of a structure.

[0002]

2. Description of the Related Art When an optical fiber is deformed by an external force, the light transmission characteristic changes due to the distortion. Therefore, by measuring the change in the light transmission characteristic, the degree of deformation and the deformed portion can be obtained.

It is conceivable to measure the deformation of a structure using such optical characteristics of an optical fiber. For example, if an optical fiber is provided along the inner surface of the tunnel, it is possible to detect the deformation of the tunnel caused by a landslide or the like.

[0004]

However, if an optical fiber is to be provided on the inner surface of an existing tunnel, for example, a problem of the construction period arises. In other words, since trains and trains pass through the tunnel on a daily basis, it is practically not permissible to lay out fiber optics easily, and work must be done promptly during limited hours such as late at night. .

Accordingly, it is an object of the present invention to provide a method of arranging an optical fiber for measuring deformation of a structure, which can quickly arrange an optical fiber.

[0006]

According to the present invention, there is provided a method for arranging an optical fiber for measuring deformation of a structure, comprising the steps of arranging a bendable pipe along the surface of the structure, and then arranging the optical fiber inside the pipe. And then the optical fiber and the pipe are integrated.

In the above structure, a pipe is provided on the surface of a structure such as a tunnel. In this case, the pipe is arranged while being bent along the surface of the uneven structure. Next, the optical fiber is inserted through the inside of the pipe at a stretch by air blow or pulling of a pull cord, and the optical fiber and the pipe are integrated.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view of a tunnel provided with a pipe through which an optical fiber is inserted, FIG. 2 is a cross-sectional view of the tunnel during insertion of the optical fiber, FIG. 3 is an explanatory view of a method of inserting the optical fiber, and FIG. It is sectional drawing of the inserted pipe.

In FIG. 1 and FIG. 2, a pipe 2 is disposed along an arch-like inner surface of a tunnel 1. In the tunnel 1, a number of pipes 2 are connected and arranged. The pipe 2 is fixed to the inner surface of the tunnel 1 by a fastener such as a metal fitting or a bond (not shown).

The pipe 2 is a flexible pipe made of a synthetic resin or the like, and can be disposed along the surface of a structure such as a tunnel while freely bending the pipe. An optical fiber 3 is inserted into the inside of the pipe 2. The optical fiber 3 is wound around a spool 4 and inserted into the pipe 2 while being led out of the spool 4.

Next, a method of disposing an optical fiber will be described in the order of steps. First, as shown in FIGS. 1 and 2, the pipe 2 is disposed while being bent along the inner surface of the tunnel 1. In this case, since the pipe 2 is freely bendable, even if the surface of a structure such as the tunnel 1 is non-planar and has irregularities or curvature, the pipe 2 can be bent freely along the surface thereof. Can be arranged. After arranging the desired length of the pipe 2, the optical fiber 3 is inserted into the pipe 2.

FIG. 3A shows a first method of inserting the optical fiber 3 into the pipe 2. In this method, an air flow N is caused to flow through the pipe 2 by air blow, and the air flow N
To insert the optical fiber 3 into the pipe 2.

FIG. 3B shows a second method of inserting the optical fiber 3 into the pipe 2. In this method, a pulling string 5 such as a wire is attached to the tip of the optical fiber 3 and the string 5 protruding from the downstream end of the pipe 2 is held and pulled by a fingertip to pull the optical fiber 3. This is a method of towing and inserting (see arrow). String-like body 5
For example, the pipe 2 may be previously inserted into the pipe 2 by the above-described air flow, or the pipe 2 in which the string 5 is inserted in advance may be disposed on the inner surface of the tunnel 1. Due to its nature, the installation work of the pipe 2 may be interrupted on the way, and when the work is stopped, the extra length of the pipe may be cut and the cut portion may be connected to be connected in the next work. Therefore, even if the pipe arrangement is interrupted on the way, there is no particular inconvenience in the passage of trains and vehicles, but the optical fiber is easily damaged, and if the cut one is reconnected, the signal at the connection point will be lost. Loss occurs. For this reason, it is desirable that the insertion of the optical fiber 3 into the pipe 2 be completed all at once in a short time.

The optical fiber 3 must be integrally deformed with the pipe 2 by an external force. Therefore, after the optical fiber 3 is inserted through the pipe 2, the optical fiber 3 and the pipe 2 must be integrated. Therefore, next, some examples of this integration method will be described.

FIG. 4 shows a first method. In this example, the pipe 2 is made of a heat-shrinkable synthetic resin. FIG. 4A shows a state before the heat shrinkage. Optical fiber 3
As shown in the figure, the inner diameter of the pipe 2 is considerably larger than the diameter of the optical fiber 3 so as to facilitate the insertion.

Heat is applied to the pipe 2 by, for example, pouring hot water, so that the pipe 2 is thermally contracted. FIG. 4B shows a state after the heat shrinkage, and the pipe 2 and the optical fiber 3 are completely integrated. This method has an advantage that the entire outer peripheral surface of the optical fiber 3 is integrated with the entire inner peripheral surface of the pipe 2 so that the pipe 2 and the optical fiber 3 can be reliably and integrally deformed. When the pipe 2 and the optical fiber 3 are integrated as described above, when the pipe 2 is deformed by an external force, the optical fiber 3 is similarly deformed with good responsiveness. The degree of this deformation and the location of the deformation can be easily obtained by well-known optical measuring means.

FIG. 5 is a cross-sectional view of a pipe through which an optical fiber is inserted, and shows another method of integrating the pipe and the optical fiber. A thermosetting resin or U
Fast-curing bond 6 such as photo-curing resin such as V resin
After the optical fiber 3 is inserted into the pipe 2, the bond 6 is cured by heating H or irradiating light to integrate the optical fiber 3 with the pipe 2. When a photocurable resin is used as the bond 6, the pipe 2 should have a light transmitting property.

FIG. 6 is a sectional view of a pipe through which an optical fiber is inserted, and shows still another method. In this example, the bond 6 similar to the above is applied to the surface of the optical fiber 3, and is heated H or irradiated with light to form the bond 6.
Is cured to integrate the optical fiber 3 with the pipe 2. As described above, various methods are possible for integrating the pipe and the optical fiber. In the above-described embodiment, a tunnel has been described as an example. However, a target structure is not limited to a tunnel.

[0019]

As described above, according to the present invention, a bendable pipe is first provided on the surface of a structure, and then the optical fiber is inserted through the pipe. And can be quickly arranged. Further, the pipe can be arranged along the uneven surface or the curved surface of the structure while bending the pipe, so that the degree of freedom in design and construction is extremely large.

[Brief description of the drawings]

FIG. 1 is a perspective view of a tunnel provided with a pipe through which an optical fiber is inserted.

FIG. 2 is a cross-sectional view of a tunnel during insertion of an optical fiber.

FIG. 3 is an explanatory diagram of a method of inserting an optical fiber.

FIG. 4 is a sectional view of a pipe through which an optical fiber is inserted.

FIG. 5 is a cross-sectional view of a pipe through which an optical fiber is inserted.

FIG. 6 is a sectional view of a pipe through which an optical fiber is inserted.

[Explanation of symbols]

 Reference Signs List 1 tunnel 2 pipe 3 optical fiber 5 string 6 bond

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiaki Inoue 5-717-1 Fukahori-cho, Nagasaki-city, Nagasaki Prefecture Inside Nagasaki Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Toshio Nakamura 5-chome, Fukahori-cho, Nagasaki-city, Nagasaki Prefecture No. 717 No. 1 F-term in Nagasaki Laboratory, Mitsubishi Heavy Industries, Ltd. (reference) 2F065 AA65 CC40 LL02 2G086 DD05 2H038 AA02 CA68 CA69

Claims (1)

[Claims] 1. A structure according to claim 1, wherein a flexible pipe is provided along the surface of the structure, an optical fiber is inserted into the pipe, and the optical fiber and the pipe are integrated. How to install optical fiber for deformation measurement.