JPH09261831A - Sub-duct fixing method - Google Patents

Abstract

(57) [Abstract] (Correction) [PROBLEMS] To fix a sub-duct used for laying an optical cable in an underground buried pipe at the end of the pipe by a good workability and a simple method. SOLUTION: The power cable 2 and the sub-duct 3 laid in the underground buried pipe 1 are first wound around the power cable at a position where it is easy to work, and a rubber sheet 6 is wound around the power cable as a cushioning material. Contact the sub-duct from the
The sub-duct is fixed by fastening the power cable and the sub-duct together with the band 5 from above the rubber sheet. In this fixing method, a simple member can be used for fixing without being affected by the size of the power cable and the size of the sub duct, and the fixing position can be selected so that it is easy to work.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of fixing a sub-duct used for laying an optical cable in an underground buried conduit at the end of the conduit.

[0002]

2. Description of the Related Art A sub-duct using a special PVC pipe for laying an optical cable is further laid in an underground buried pipeline where an electric power cable has already been laid, and the optical cable is laid therein. The sub-duct method is used. Since the sub-duct is made of plastic material, it expands and contracts under the influence of temperature changes in the pipeline. Therefore, the sub-duct must be fixed at the end of the conduit, and conventionally, a method of fixing the sub-duct using a conduit opening waterproofing device has been performed. FIG. 3 shows a fixing state of the sub-duct when the conduit opening waterproof device is used. Particularly, FIG. 3 (a) is a view of the end of the conduit as seen from the front, and the end portion of the underground buried pipe 1 is shown. A conduit opening waterproof device 4 is installed inside. The conduit opening waterproofing device 4 includes the cables 2 a (u) for each phase of the power cable 2.
Phase), 2b (v phase), 2c (w phase) and a rubber packing provided with holes through which the sub-duct 3 passes, respectively.
As shown in (b), the bolt is pressed against the inner wall of the buried pipe 1 to seal the end of the conduit.

[0003]

However, there are the following problems in the sub-duct fixing method using the conventional conduit opening waterproofing device. 1. It is necessary to prepare various kinds of rubber packing so that different cable sizes and sub-duct sizes can be accommodated. 2. Workability is poor due to work in a narrow space in the pipeline.
In particular, at the end of the pipeline, the cables are congested and the work space is narrow, which further deteriorates workability. 3. The conduit opening waterproofing device was originally developed for the purpose of waterproofing the conduit, and has a complicated structure as a sub-duct fixing device and is high in cost. Therefore, it is useless to use the conduit opening waterproof device for holding the sub-duct at a place where waterproofness is not required. An object of the present invention is to provide a simple sub-duct fixing method that can easily cope with changes in cable size and sub-duct size, and has good workability.

[0004]

According to the present invention, unlike the conventional method, the sub-duct is attached along with the power cable at a position near the end of the pipeline where it is easy to work, without using a waterproofing device for the pipeline inlet. It is a solution to the problem.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION An example of a sub-duct fixing method of the present invention will be described with reference to FIG. FIG. 1A shows a fixed state in the vicinity of the end of the underground buried pipeline. The power cable 2 (triplex cable in the figure) and the sub-duct 3 laid in the underground pipe 1 are made of a cushioning material for protecting the power cable 2 at a position near the end of the pipeline where it is easy to work. The protector, for example, the rubber sheet 6 is wound and fixed, and then the fixing member, for example, the band 5 is used to integrally tighten and fix the electric power cable 2 wound with the rubber sheet 6 and the sub-duct. FIG. 1B is a view of the fixed state as seen from the front of the conduit end, and shows cables of each phase of the power cable as 2a, 2b, and 2c. In addition,
Wrap the rubber sheet so that it does not affect the cable when the band is tightened.

Instead of the rubber sheet, a protector made of sponge tape or impregnated burlap cloth may be used.
Further, as the fixing member, an adhesive tape, a clamp, or the like may be used instead of the band. In the example shown in FIG. 1, a rubber sheet is used to have a cushioning effect. However, when it is not necessary to use such a protector, as shown in FIG. 2, the power cable 2 (2a, 2b) is used. 2c) may be directly attached to the sub-duct 3, and the power cable 2 and the sub-duct 3 may be fixed by using a fixing member such as the adhesive tape 7.

[0007]

According to the sub-duct fixing method of the present invention,
The workability can be remarkably improved because the work can be performed by using a simple member without being affected by the cable size and the sub-duct size, and the workable position can be selected. Therefore, all the problems of the conventional fixing method using the conduit opening waterproof device can be solved.

[Brief description of drawings]

FIG. 1 is a diagram showing a first sub-duct fixing method of the present invention, and FIG. 1 (a) is a perspective view in the vicinity of a pipe end. (B) is a front view of a pipe end.

FIG. 2 is a front view of a pipeline end showing a second sub-duct fixing method of the present invention.

FIG. 3 is a view showing a conventional method for fixing a duct, in which (a) is a front view of a pipe end. (B) is a sectional side view showing a bolted state.

[Explanation of symbols]

 1 Underground pipe 2 Power cable 3 Sub-duct 4 Pipe entrance waterproof device 5 Band 6 Rubber sheet 7 Adhesive tape

Front page continuation (72) Inventor Noboru Shibata 5-1-1, Hidaka-cho, Hitachi-shi, Ibaraki Hitachi Hidden Cable Co., Ltd. (72) Inventor Hitoshi Nojo 5-chome, Hidaka-cho, Hitachi-shi, Ibaraki No. 1 in Hitachi Cable Co., Ltd. Hidaka factory

Claims (4)

[Claims] 1. A power cable is wrapped around a protective body made of a cushioning material in the vicinity of a pipeline end of an underground buried pipeline, and a sub-duct is brought into contact with the power cable from above, and the power cable is fed from above the protective body. And a sub-duct fixing method for integrally fixing the sub-duct with a fixing member. 2. The sub-duct fixing method according to claim 1, wherein the protector is a rubber sheet. 3. A sub-duct fixing method in which a sub-duct is directly attached to a power cable in the vicinity of a conduit end of an underground buried conduit, and the power cable and the sub-duct are integrally fixed using a fixing member. 4. The sub-duct fixing method according to claim 1, wherein the fixing member is an adhesive tape.