JP2545336B2 - Waterproofing method of cable conduit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waterproofing method for a cable conduit opening.

[0002]

2. Description of the Related Art Underground transmission lines are laid in a pipeline buried in the ground, and the pipeline is connected to a pipeline mouth that connects the pipeline and a manhole installed in the pipeline. A waterproof device is installed to prevent water from leaking into the manhole.

When the power transmission line is a single line, water leakage from the conduit can be easily prevented by installing a waterproof device, but a three-phase stranded wire, especially a three-phase stranded power cable used for power transmission between substations. In this case, as shown in FIG. 9, since a comparatively large void portion 2 extending in the cable length direction is formed in the central portion of the power cable 1, it is necessary to take measures to prevent water leakage from the void portion 2. By the way, in the periphery of the void 2,
The three-phase twisted cable single wires 1a, 1a, 1a are in contact with each other to form a seal 1b in the cable length direction, so the above-mentioned void 2 is theoretically blocked from the inside of the pipe line, but in reality, Since the twist may be loosened to some extent, the seal is not perfect, and water will enter the void 2 from the inside of the pipe,
It may cause water leakage from the conduit. Conventionally, various studies have been made to prevent such leakage of water from the void portion 2, but an appropriate measure has not been provided yet.

The present invention has been made for the purpose of solving such a conventional problem.

[0005]

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a waterproofing method for a cable conduit opening for waterproofing by installing a waterproofing device between a three-phase stranded power cable laid in the conduit and the inner circumference of the conduit, within the central cavity portion of the three-phase twisting power cable, the water-swelling fibers of ultra intake <br/> aqueous, together Add packed to occupy the waterproof device and substantially the same position in the cable longitudinal direction, at least of the water expansion fibers The present invention relates to a waterproofing method for a cable conduit opening, which is characterized in that other kinds of fibers are filled inside the conduit.

The super-water-absorbent water-expandable fiber used in the method of the present invention is easily available as a commercial product. In particular, Lanseal F (trademark, manufactured by Toyobo Co., Ltd.) is composed of an acrylic fiber inner layer and a super-water-absorbent resin. It has a two-layer structure with an outer layer, and when it comes into contact with water, it immediately absorbs water and swells. For example, the diameter expands about 12 times and the fiber length is 30 to 60 mm.
It is a long fiber of a certain degree, and the fibers can be firmly entangled with each other, so that it is suitable for use in the method of the present invention.

[0008]

An embodiment of the method of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows one embodiment of the method of the present invention. Between the three-phase twisted power cable 1 laid in the conduit 3 and the inner circumference of the conduit 3, as in the usual manner, inside the conduit port 3a. The water is stopped by the waterproof device 4 installed at.

In the method of the present invention, before the waterproof device 4 is installed or after the waterproof device 4 is installed as shown in FIG. 1, for the purpose of preventing water leakage from the central void 2 of the cable 1, the void 2 is provided. Superabsorbent water-expandable fibers 5 are packed therein.

When filling the water-expandable fiber 5 in the void portion 2, an appropriate tool is used by working in the manhole 6 between the three single wires 1a, 1a, 1a constituting the cable 1. It is applied and forced open. This push-opening condition is shown in FIGS. 1 and 2, and the water-expandable fiber 5 is entangled in a cotton shape and shaped into a rope shape (see FIG. 1), and is pushed into the void 2 through the push-opening gap 7. It can be packed by pushing it in. Since the water-expanded fibers 5 greatly expand due to water absorption, there is no particular problem even if some gaps remain during packing.

After the work of packing the water-expandable fibers 5 is completed, when the cable 1 is released from the forced opening, the cable 1 is automatically restored to the original three-phase twist state due to its elasticity.

The state after the filling operation of the water expansion fibers 5 is completed is shown in FIGS. As shown in FIG. 3, a few gaps 2a are left around the packed water-expansion fibers 5, for example, but there is no particular problem because the gaps 2a can be filled by expansion after water absorption. Further, the packing position needs to coincide with the installation position of the waterproof device 4 as shown in FIG. 4, which means that when the water expansion fiber 5 expands, the cable 1 receives expansion pressure from the inside of the void 2. This is to prevent it from being pushed open to the outside.

The filling length of the water-expandable fiber 5 may be slightly larger than the installation width of the waterproof device 4 as shown in FIG. 4, but as long as it matches the installation position of the waterproof device 4, the filling The length of the length is not particularly limited.

Water-expanding fibers 5 packed in the voids 2
When it comes into contact with water, it quickly absorbs it and swells, for example, the fiber diameter expands about 12 times, so after the water absorption expansion, the void 2 is filled in a compacted state and the gap is completely eliminated.
Moreover, since the above-mentioned fiber 5 does not allow water once absorbed to escape to the outside, and since it is a fiber, it does not get entangled with each other and is not washed away by water.
This state can be maintained semi-permanently, and stable leakage prevention results can be obtained for a long period of time.

The water-expanded fiber causes sliminess when it comes into contact with water. Thus when not led to yet sufficiently expansion of the filling early, hate there as they may lack the holding stability of the filling state, as shown in FIG. 4, the side receiving the conduit inner or pressure of water-swelling fibers 5 Further, if necessary, fibers 8 and 9 that do not cause slime even if they come into contact with water are filled in the outside of the pipeline that is not subjected to water pressure, for example, in the state of a non-woven fabric, and the water expansion fiber 5
To prevent it from moving from the filling position. Incidentally, since many natural fibers, synthetic fibers, chemical fibers, etc. do not produce slime even when they come into contact with water, the fibers 8 and 9 may be appropriately selected from these fibers and used.

The waterproof device 4 installed between the three-phase twisted power cable 1 and the inner circumference of the conduit 3 is known, and various configurations have been already proposed.

In the construction method of the present invention, various known constructions can be used as the waterproofing device 4, but FIG.
The waterproof device having the structure shown in FIG. 7 is particularly suitable for the method of the present invention because it can maintain excellent water leakage prevention performance for a long period of time.

FIG. 5 shows a waterproof mat 4a which is one of the components of the waterproof device 4. The waterproof mat 4a is made of super absorbent water-expandable fiber and has an outer diameter substantially equal to the inner diameter of the conduit 3. Further, in the central portion, a mounting hole 4a having a shape substantially equal to the cross-sectional shape of the three-phase twisted power cable 1 is formed.
₁ is formed. Waterproof mat 4a is divided into three at the cutting line 4a ₂ in order to allow attachment to three-phase twisting power cable 1 from the outer side, each of the divided parts of the bolt through hole 4a ₃ is formed.

FIG. 6 shows a rubber packing 4b, which is one of the other components of the waterproofing device 4, and the packing 4b is
The outer diameter of the waterproof mat 4a is slightly smaller than that of the waterproof mat 4a.
slightly enlarged mounting holes 4b than mounting hole 4a ₁ of a
₁ and one pair before and after is used. Rubber packing 4
In b, since the mounting hole 4b ₁ is enlarged and the elasticity of the rubber can be utilized, two divisions by the cutting line 4b ₂ are sufficient. Waterproof mat 4a for rubber packing 4b
Bolt holes 4a ₃ and the bolt through hole 4b ₃ at a position matching
Is provided.

FIG. 7 shows a retainer 4c which is one of the remaining components of the waterproof device 4. Retainer 4c has an outer diameter outer diameter or approximately equal to or which slightly less than the rubber packing 4b, mounting holes 4b ₁ having the same shape of the packing 4b, and mounting holes 4c ₁ of the same size, the front and rear pair Is used. The presser foot 4c is divided into three pieces 41, and the piece 41 has concave and convex step portions 41a, 41 for joining at both ends.
b, it is configured to be joined by inserting the bolt 4d into the bolt through holes 41c, 41c formed in the uneven step portions 41a, 41b in a state where the uneven step portions 41a, 41b are overlapped. There is.

FIG. 8 shows a condition when the waterproof device 4 is installed. Under the temporary assembled condition shown on the right side of FIG. 8, each component is moved along the cable 1 to a predetermined portion of the conduit opening 3a, and then, , The bolts 4d and the nuts 4e are fastened to fasten the respective components to form the main assembly, so that the waterproof device 4 can be installed at a predetermined portion.

In this installed state, the outer peripheral portion of the waterproof mat 4a is exposed to the outside due to the small outer diameters of the presser tool 4c and the rubber packing 4b, and the mounting hole 4c provided therein.
_Since the inner diameter of the waterproof mat 4a is also exposed to the outside due to the expansion of the diameters of ₁ and 4b _1, the water-expanding fibers constituting the waterproof mat 4a are quickly exposed to the water in the conduit 3 at the exposed portion. It comes into contact with and absorbs water and expands. Due to this water absorption expansion, the waterproof mat 4a is crimped to the inner peripheral surface of the conduit 3 on the outer peripheral side and to the outer peripheral surface of the three-phase twisted power cable 1 on the inner peripheral side, and on the inner peripheral side, the outer peripheral portion of the cable 1 described above. Enter into the narrow gap. Due to the water-absorption expansion of the water-expansion fibers constituting the prevention mat 4a, even between the cable 1 and the inner circumference of the pipe line 3, a high degree of water leakage prevention effect can be obtained similarly to the case of the central void portion 2. It can be stably maintained for a long period of time.

[0024]

In the method of the present invention, since the water-expandable fibers packed in the central void portion of the three-phase twisted power cable come into contact with the water invading from inside the pipe and absorb water to expand, the water-expandable fiber is particularly dense during construction. Even if it is not filled, it can quickly become a compaction-filled state after construction, and since the fibers do not escape the absorbed water to the outside and are not swept into the water due to the entanglement of the fibers, It can be stably maintained for a long period of time, and water leakage from the central void can be reliably and reliably prevented for a long period of time. In addition,
Water-expanded fibers cause sliming when they come into contact with water and therefore fill
If the initial expansion has not yet reached full expansion,
Insufficient retention stability at the filling position, but in the present invention, a water-expanded fiber
Other fibers filled at least inside the duct than the fibers are swollen
Keep the tension fiber from the water pressure in the pipeline until it is fully expanded.
Since it functions as a protective barrier, the filling position of the water expansion fiber
It will not move out of place, and waterproof performance will be established.
It can be held as usual.

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing one implementation state of a method of the present invention.

FIG. 2 is an explanatory diagram showing the outward push-open condition of the three-phase twisted power cable.

FIG. 3 is an explanatory view showing a situation in which a water-expanded fiber is packed in a central void portion of a three-phase twisted power cable.

4 is a cross-sectional view taken along line 4-4 of FIG.

FIG. 5 is a plan view of the waterproof mat.

FIG. 6 is a plan view of rubber packing.

FIG. 7 is a plan view of a presser foot.

FIG. 8 is an explanatory diagram showing a situation from the temporary assembled state of the prevention device to the assembled state of the present invention.

FIG. 9 is an explanatory diagram showing a situation of a central void portion of a three-phase twisted power cable.

[Explanation of symbols]

 1 Three-Phase Twisted Power Cable 2 Center Gap 3 Pipeline 4 Waterproof Device 5 Water Expansion Fiber 6 Manhole 7 Push Open Gap

Claims (2)

(57) [Claims] 1. A three-phase twisted power cable laid in a pipeline.
In the waterproofing method of the cable conduit opening, where a waterproof device is installed between the pipe and the inner circumference of the conduit, a super absorbent water-expandable fiber is waterproofed in the length direction of the cable in the central void of the three-phase twisted power cable. It is packed so as to occupy substantially the same position as the device, and at least the inside of the conduit of the water-expandable fiber
A method for waterproofing a cable conduit opening, characterized in that it is filled with another type of fiber . 2. The waterproof device comprises, as a component, a waterproof mat made of super absorbent water-expandable fiber capable of waterproofing between the three-phase twisted power cable and the inner circumference of the conduit. The waterproof device according to 1 .