JPH11149022A - Optical sensor composite pipe cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical composite cable usable as a sensor for monitoring a state of a dike and also usable as an optical cable for general communication. SOLUTION: Optical fibers 1 for detecting distortion and pipes 5 for force-feeding the air are combined with a sheath 10 in one body, and a steel tape armor 11 is provided on this sheath. Changes in the state of a dike, etc., are monitored from distortion changes by connecting the distortion detecting optical sensors 1 to a BOTDR (Brillov in Optical Time Domain Reflectometer), and optical fiber units 13 are inserted into the pipes 5 for force-feeding the air and these optical fiber units 13 are used for general communication.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical sensor composite pipe cable that can be used for monitoring the condition of long-distance structures such as embankments and roads and for transmitting general information.

[0002]

2. Description of the Related Art Conventionally, installation of a sensor for monitoring the condition of a dike or a road and installation of an optical fiber cable for general communication have been performed separately. For example, various types of sensors, such as a resistance change type and a capacitance type, are used as sensors for monitoring changes in the ground of a dike, but optical fiber cables for general communication are completely separate from these sensors. Has been laid.

[0003]

However, the above sensor is a point sensor and cannot monitor a long-distance structure such as an embankment or a road along a longitudinal direction. In addition, in order to collect measurement results, a transducer and a data transmission device are required at a location where each sensor is installed, and these power sources and transmission paths also need to be separately laid. Therefore, the burden is high in terms of cost and management.

[0004] Further, if the optical fiber for general communication and the transmission path of the sensor are separately laid, two cables must be laid, and there is a problem that material costs and construction costs increase.

Accordingly, an object of the present invention is to provide an optical composite cable which can be used as a condition monitoring sensor for a dike or the like and also can be used as an optical cable for general communication.

[0006]

SUMMARY OF THE INVENTION The cable of the present invention has been made in order to achieve the above-mentioned object, and comprises an optical fiber for strain detection and a pipe for pneumatic feeding integrally integrated with a sheath,
It is characterized in that a metal sheath is provided on the outer periphery of the sheath.

Here, it is preferable that the strain detecting optical fiber is one in which a single mode optical fiber is built in a metal tube, and a filler is injected between the metal tube and the single mode optical fiber. The material of the metal tube is preferably stainless steel. Jelly, various resins, rubber, and the like can be used as the filler.

To use this optical fiber as a sensor, a BOTDR (Brillou
in Optical Time Domain Reflectometer). Thus, the strain in the optical fiber is detected to monitor the behavior of the dike or road soil in which the composite cable is embedded.

In order to integrally combine the optical fiber for strain detection and the pipe for pneumatic feeding, for example, the optical fiber for strain detection and an intervening cord are wound around the outer periphery of a core material to make the outer shape substantially circular. Winding a pneumatic feed pipe around its outer periphery may be combined. In this case, by making the outer diameter of the intervening cord equal to the outer diameter of the optical fiber for strain detection, the outer diameter after winding can be easily adjusted to a circular shape. Then, a sheath may be provided on the outer circumference of the air pressure feeding pipe, and a metal sheath may be further provided on the outer circumference.

Further, an anticorrosion layer may be formed on the outer periphery of the metal sheath provided on the outer periphery of the sheath, and the sheath may be of a direct buried type. Examples of the material of the anticorrosion layer include jute. The metal sheath may be formed by winding a steel strip or a steel wire.

The optical fiber unit is inserted into the air pressure pipe by air pressure after the composite cable is laid.
Since no tension is applied to this optical fiber unit, it is suitable for use as an information transmission path for general communication and the like. The pipe is preferably made of polyethylene or the like.

[0012] In the above-described composite cable, it is desirable that the tension member be composited together in the sheath. For example, in a cable in which a strain detection optical fiber and an intervening cord are wound around the outer periphery of the core, the core may be a tension member. As a material of the tension member, a steel wire or an aramid fiber is preferable.

[0013]

Embodiments of the present invention will be described below. FIG. 1 is a sectional view showing an optical fiber 1 for strain detection used in the composite cable of the present invention. This optical fiber 1
The single-mode optical fiber 2 is housed in a stainless steel tube 3 and a filler 4 is injected between the two.

The composite optical fiber cable shown in FIG. 2 is constituted by using the optical fiber 1 for strain detection and the pipe 5 for pneumatic feeding. This cable has a tension member 6 made of a coated steel stranded wire at the center, and several twisted optical fibers 1 for strain detection and an intervening cord 7 twisted around its outer periphery. The intervening cord 7 has substantially the same outer diameter as the strain detecting optical fiber 1, and the outer periphery of the twisted strain detecting optical fiber 1 and intervening cord 7 is wound around the holding tape 8 to form a substantially circular outer shape. I have.

A plurality of pneumatic feeding pipes 5 are twisted on the holding tape 8. The pipe 5 is for inserting an optical fiber unit 13 described later. Each of the pneumatic feeding pipes 5 is integrated by applying a wrap sheath 9 on the outer periphery, and further, a polyethylene sheath is provided on the outer periphery thereof.
10 has been given. Then, a steel strip armor 11 was provided on the polyethylene sheath 10, and an anticorrosion layer 12 was further formed thereon so that it could be directly buried and used.

When such a composite cable is used, BOTD is attached to the end of the single mode optical fiber 2.
R (not shown). In this method, a light pulse is incident on an optical fiber, and the generation wavelength of Brillouin scattered light in the backscattered light is measured to detect distortion. Then, the position where the Brillouin scattered light of a certain wavelength occurs is specified by the time from when the light pulse is incident to when the backscattered light returns to the incident end. Therefore, data of Brillouin scattered light along the longitudinal direction of the optical fiber can be obtained, and a change in strain due to a change in tension of the optical fiber can be detected.

The strain detecting optical fiber 1 is twisted and compounded together with the intervening cord 7 having the same diameter, and the tension at the time of manufacture remains as residual strain. Observed as a change in distortion. Therefore, if the strain is monitored by the BOTDR, the behavior of the soil in which the composite cable is buried can be monitored.
In this case, the optical fiber for strain detection itself functions as a sensor and a transmission path for measurement results, so that measurement results can be monitored collectively at the BOTDR installation location, and an individual power supply can be installed or transmission paths can be installed. There is no need to lay.

After the cable is laid in the pipe 5, the optical fiber unit 13 is pumped by air. Since no tension is applied to the optical fiber unit 13, it may be used for general communication. It is desirable that a plurality of pipes 5 are prepared in consideration of an increase in the amount of transmission in the future, and that the optical fiber unit 13 can be pressure-fed inside if necessary.

As described above, the optical fiber for strain sensor 1 and the pipe 5 are integrally combined to form a directly buried cable, so that monitoring of soil behavior and information transmission can be performed with a single cable. Can be. For example, when buried in a dike,
It can be used not only for transmission of river information systems, but also for monitoring the behavior of levees during floods. Further, when laid on a road, it can be used not only as a transmission path for a road disaster prevention (information) system but also for monitoring road abnormalities such as cracks.

[0020]

As described above, according to the composite cable of the present invention, a single composite cable can have a function as a general information transmission path and a function as a strain monitoring sensor. In that case, there is no need to separately install special sensors and power supplies or lay transmission lines, which is economical.
In addition, it is possible to continuously monitor a change in distortion along an installation road, and is most suitable for installation on a long-distance structure such as a road.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a strain detection optical fiber used for a cable of the present invention.

FIG. 2 is a sectional view of the cable of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Strain detection optical fiber 2 Single mode optical fiber strand 3 Stainless steel tube 4 Filler 5 Pneumatic feed pipe 6 Tension member 7 Intermediate string 8 Holding tape 9 Wrap sheath 10 Polyethylene sheath 11 Steel strip armor 12 Corrosion prevention layer 13 Optical fiber unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01B 11/00 G02B 6/00 B (72) Inventor Kazuki Sogabe 1-3-1 Shimaya, Konohana-ku, Osaka Sumitomo Electric Industries, Ltd. (72) Inventor Tsuneo Mori 1-3-1, Shimaya, Konohana-ku, Osaka-shi Sumitomo Electric Industries, Ltd.Osaka Works (72) Inventor Toshihiko Nishihata 2-2-10 Shinmachi, Hirakata-shi, Osaka Ministry of Construction Kinki Regional Construction Bureau Yodogawa Construction Office

Claims (4)

[Claims] 1. An optical sensor composite pipe cable comprising: an optical fiber for strain detection and a pipe for pneumatic feeding integrally formed with a sheath; and a metal sheath on the outer periphery of the sheath. 2. The strain detecting optical fiber according to claim 1, wherein a single mode optical fiber is built in the metal tube, and a filler is injected between the metal tube and the single mode optical fiber. 2. The optical sensor composite pipe cable according to 1. 3. An optical fiber for strain detection and an intermediary cord having the same outer diameter as the optical fiber are arranged and arranged on the outer periphery of the core material, and an air pressure feeding pipe is assembled on the outer periphery and integrated with a sheath. 2. The optical sensor composite pipe cable according to claim 1, wherein an anticorrosion layer is formed on the outer periphery of the metal sheath to form a directly embedded type. 4. The optical sensor composite pipe cable according to claim 1, wherein the tension member is also composited together.