JP2001224112A - Method of removing underground cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently remove for reuse of a conduit an underground cable that is bonded to the inner face of the conduit and is incapable of being withdrawn. SOLUTION: The power cable 3 threaded through the conduit 2 is cut in a manhole 1, and a propelling tube 9 is fit onto the cable, starting at the cut end. The propelling tubes are added and pushed into the conduit 2 by a propulsion device 20, and the bonded portion of the cable is stripped by a bit 10 at the tip of the leading propelling tube. Subsequently, the cable 3 is pulled out of the conduit 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underground cable which is no longer required, and more particularly, an underground cable which can be removed from a power cable which is fixed to a pipeline and cannot be removed by a simple method. The removal method.

[0002]

2. Description of the Related Art It is desired that underground cables that have become used after their useful lives have expired be removed from the pipeline through which the cables pass.

[0003] The removal is usually performed by cutting the power cable to be removed at a manhole or the like, pulling it in one direction by applying a pulling force to one end with a winch, and winding it up on a drum on a removal vehicle that is standing by on the manhole. It is done in a progressive manner.

[0004]

As a result of attempting to remove the power cable by the above-mentioned conventional method, there are not a few power cables remaining in the pipeline without being removed.

[0005] The cause of the inability to remove is the sticking of the cable to the pipeline. The sticking is roughly classified into two types, one due to an external factor and one due to an internal factor.

[0006] As an external factor, for example, a soil conditioner or the like permeates into the pipeline and solidifies over time to adhere the cable and the pipeline.

Further, as an internal factor, there is an example in which the corrosion protection layer swells due to deterioration of the cable, oil leakage, and the like, and the pipe is clogged.

[0008] Withdrawal removal by a simple method cannot cope with an increase in pullout resistance due to sticking. If the tension is applied and the cable is pulled out with force, the cable may be broken, and the jacket or the like of the fixing portion may remain attached to the pipe.
Further, if there is an abnormality in the inside of the conduit or the fixing range is wide, the cable may not move at all.

[0009] A power cable that cannot be removed for such a reason and prevents the pipeline from being reused. Since the construction of a new pipeline not only requires enormous costs but also necessitates the securing of a new site, it is strongly desired that the remaining cables be removed so that the existing pipeline can be reused.

[0010] In order to meet the demand, it has been tried to insert a cutting machine into a pipeline and scrape the entire cable, but this method takes too much time for removal. Further, it is difficult to cut a power cable which is a composite of a metal and a non-metal, and the abrasion and welding of the cutting edge are severe. In addition to this, it is not practical because there are problems such as the difficulty in collecting and processing chips.

Accordingly, an object of the present invention is to provide a highly practical removal method capable of smoothly removing a fixed underground cable.

[0012]

In order to solve the above-mentioned problems, according to the present invention, a power cable to be removed, which is passed through a pipe, is cut at a work site, and is cut from a cut end to the outside of the cable. The propulsion pipe is fitted, the propulsion device is pushed into the pipe while adding the propulsion pipe, and the power cable fixed to the pipe with the scraper or bit provided at the tip of the leading propulsion pipe is peeled off from the pipe. The power cable was pulled out of the pipeline.

Further, if necessary, the propulsion pipe is pushed into the pipeline while rotating, and the cable fixing portion is cut off with a scraper or bit at the tip of the leading propulsion pipe.

Further, when there is a bent portion in the pipeline, a universal joint capable of transmitting a rotational force is provided in the middle of the propulsion tube or at a connection portion, and the propulsion tube added is bent while being bent along the pipeline. It was pushed into the pipeline.

In these construction methods, it is preferable to apply tension to the power cable on the pushing side during pushing of the propulsion pipe.

[0016]

According to the method of the present invention, the propulsion pipe is guided by the inner cable and reliably pushed between the pipe and the cable. Therefore, the fixed cable is reliably scooped by a scraper or a bit provided at the tip of the leading propulsion pipe, and peeled off from the pipe.

When the propulsion pipe is pushed in while being rotated, the fixed portion is cut off by the scraper or the bit, so that even if the cable is firmly adhered to the pipe, reliable peeling is performed.

On the pushing side, when tension is applied to the cable and the propulsion pipe is pushed in this state, the cable is pulled while being lifted by the propulsion pipe.
A preferable form of peeling force is applied to the fixing portion, and the cable is more easily peeled. The adhesive tape stuck on the flat surface is not easily peeled off when one end is pinched and pulled in the longitudinal direction, but can be easily peeled off when pulled upward while being pulled upward. This is the same reason.

Further, if tension is applied to the cable to remove the fixed portion, even if the fixed portion still remains, the cable may move when the pull-out resistance loses the tension, and the cable may be pulled out. In this case, there is no need to continue pushing the propulsion tube any further, and the removal can be performed more efficiently.

[0020]

FIG. 1 shows an outline of the method of the present invention. In the figure, 1 is a manhole, 2 is an underground pipe line opened to the manhole 1, 3 is a power cable to be removed remaining in the pipe line 2, 4 is a hydraulic unit arranged on the manhole, 5 is A temporary frame having a reaction force receiver 6, 2
Reference numeral 0 denotes a propulsion device installed in the manhole 1.

As shown in the figure, a temporary frame 5 is installed in the manhole 1 and the propulsion device 2 is placed on the temporary frame 5.
Set 0. At this time, the slide unit 22 of the propulsion device 20 is positioned on the extension of the pipeline 2 where the work is performed by adjusting the height with the temporary frame 5.

As shown in FIGS. 1 and 2, the propulsion device 20 includes a slide unit 22 supported by a slide base 21.
, A hydraulic cylinder 24 provided between the slide unit 22 and the support body 23, a face plate 25 provided at the front end of the slide unit 22, and a rotary drive device for the face plate built in the slide unit 22 (in FIG. And a power transmission gear 27). The cylinder 24 is operated by the hydraulic pressure supplied from the hydraulic unit 4 to push the face plate 25 together with the slide unit 22, and the hydraulic motor 26 moves the face plate 25. It is designed to rotate.

As this propulsion device, a device employed in a commercially available casing excavator or the like can be used, and is not limited to the one shown in the drawings.
It is necessary to have a hole through which the pulling wire 7 passes.
The illustrated device provides a guide tube 28 to create the hole.

Before setting the propulsion device 20, the power cable 3 is cut at two manholes. When tension is applied to the cable, an eye fitting 8 for connecting the pulling wire 7 is attached to the cut end.

When the above preparations are completed, the propulsion pipe 9 is fitted to the outside of the power cable 3 from the cut end, the rear end of the pipe is fixed to the face plate 25, and further connected to the eye fitting 8, and the guide pipe 28 is connected. The pulling wire 7 pulled out of the cable 7 is retained at an appropriate position, tension is applied to the cable 3 by the wire 7, and then pushing of the propulsion pipe 9 is started.

The first propulsion pipe to be pushed in first has a cutting bit or a scraper provided at the tip. 3 to 5 show specific examples of the cutting bit 10. FIG. The bit shown in FIGS. 3 and 4 is effective when the fixed portion is solidified by a concrete material, a ground improvement agent, or the like. The bit 10 of FIG. 5 has a taper angle of α at the tip and θ at the tip edge.
It has a rake angle, making it suitable as a scraper. The bit shown in FIG. 5 is effective for peeling off a relatively soft fixed portion caused by swelling of the cable and for propulsion. When used for propulsion, good results were obtained in experiments when α was 0 ° and θ was 60 °. When peeling off the fixed portion due to swelling of the cable, both α and θ are preferably 45 ° to 60 °. The bit suitable for propulsion and the bit suitable for peeling off the fixed portion can be used while being replaced depending on the situation.

The propulsion pipe 9 is pushed into the pipe 2 while being rotated by the propulsion device 20. When the slide unit 22 reaches the end point of the stroke, the pushing is temporarily stopped, the slide unit 22 is retracted to the initial position, the propulsion pipe 9 is added, and the pushing is resumed.

In this way, the propulsion pipe 9 is pushed into the pipe line 2 while being sequentially added. If the tensioned power cable 3 moves during the pushing, the pushing is stopped at that stage, and the cable 3 is pulled out from the pipeline 2. The pulling-out is performed by winding the wire 7 with a winch or the like, pulling the cable end out of the manhole, and winding the wire 7 on a drum on the removing vehicle while applying a removing force with a removing device of a removing vehicle that is standing by on the ground. I can do it. The illustrated propulsion device 20
The cable 3 can be pulled out through the guide tube 28, and the work is easy.

If the cable does not move on the way, the pushing is continued while adding the propulsion pipe.

If the span between the manholes is too long and the pushing from one side cannot be performed stably, after peeling off the cable to the middle point of the pipeline 2, the propulsion device 20 is moved to the adjacent manhole. Do the same from the other side.

The rotation of the propulsion pipe 9 in this method may be any of continuous rotation in one direction, rotation while being reversed at a constant period, and rolling motion within a predetermined angle range. The rotation speed should not be too high in order to reduce the power consumption, protect the connection portion of the propulsion pipe, and prevent the cable from being cut off. In high-speed rotation, there is a possibility that the cable is scraped off by the bit at the tip. Also, the propulsion device installed in the manhole is preferably a small one, but as this device increases the rotational speed, the pushing force decreases, so
If the rotation is accelerated with a device with limited ability, the pushability is also sacrificed. Depending on the situation of sticking, even if the propulsion tube is pushed in without rotation, the purpose of peeling is achieved. A particularly preferred method is to apply rotation only when the indentation pressure exceeds a set value, and to proceed without rotation when tight indentation resistance does not work.

When the propulsion pipe 9 is pushed in while being rotated, the fixed portion is scraped off and chips are generated. Therefore, it is preferable to reduce the amount of chips generated by rotating the propulsion tube 9 to a minimum necessary amount.

Chips can also form when no rotation is applied. If the chips flow between the cable and the propulsion pipe and become clogged in the propulsion pipe, it will not be able to be pushed in smoothly.If there is a concern that the chips may be clogged, pressurized water or compressed air may be introduced to flush the chips, It is possible to adopt a method of suppressing the inflow of chips by pushing the pipe while periodically reversing and retreating the pipe.

When the pipe 2 has a bent portion, it is necessary to bend the extended propulsion pipe along the bent portion of the pipe. At that time, a universal joint is provided in the longitudinal direction of the propulsion pipe 9 or at a connection portion to give a degree of freedom of bending. The universal joint needs to be capable of transmitting a rotational force when performing a rotational push. There are various types of such universal joints including a universal joint. An appropriate one may be selected and used.

The underground cable conduit has a gentle curve at the bent portion because the underground cable is subject to bending restrictions.
Thus, the universal joint may be slightly bendable. In the construction method of the present invention, the leading propulsion pipe is guided by the cable and the pipeline, so if the propulsion pipe is given a degree of freedom of bending,
Work can be carried out without problems even in a bent pipe.

When the propulsion pipe 9 is attached with a spherical or hemispherical tip made of a wear-resistant material (for example, cemented carbide) on its outer surface, friction with the pipe line 2 is reduced. it can.

This propulsion pipe 9 is shorter than the stroke of the propulsion device 20 in order to make it possible to replenish it.
If it is too short, the number of refills increases, which is not desirable.
An appropriate length is set in consideration of these factors and the curvature of the pipeline 2. Appropriate lengths are expected to be on the order of 500-1000 mm, but are not so limited.

If there is no problem in strength and reliability, it is conceivable to divide the propulsion pipe 9 vertically into two parts so that it can be opened halfway. Also, when tension is applied to the cable 3, the extension propulsion pipe can be attached without removing the wire 7.

[0039]

As described above, in the method of the present invention, the propulsion pipe is fitted to the outside of the cable, and the propulsion pipe is pushed into the pipe while adding the propulsion pipe, and is fixed by the scraper or the bit at the tip of the head propulsion pipe. Since the cable is peeled off from the pipeline, the cable that has not been pulled out by the conventional method can be reliably and efficiently removed and the existing pipeline can be reused.

In the case where the propulsion tube is pushed in while being rotated or the cable is tensioned to proceed with the work, the peeling of the fixed portion proceeds more smoothly, and the work efficiency is further improved.

Further, by giving a degree of freedom to the propulsion pipe added by using a universal joint, it is possible to cope with a pipe having a bent portion, and the cable remaining in the pipe is completely eliminated, and the existing pipe is removed. It is possible to make the best use of the pipeline.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an outline of a method of the present invention.

FIG. 2 is a cross-sectional plan view schematically illustrating an example of a propulsion device.

FIG. 3 is a perspective view showing an example of a cutting bit.

FIG. 4 is a perspective view showing another example of a cutting bit.

5A is a perspective view showing still another example of the cutting bit, and FIG. 5B is a sectional view of the bit shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Manhole 2 Pipeline 3 Power cable 4 Hydraulic unit 5 Temporary frame 7 Traction wire 8 Eye fitting 9 Propulsion pipe 10 Cutting bit 20 Propulsion device

Claims (4)

[Claims] 1. A power cable to be removed, which is passed through a pipeline, is cut at a work place, a propulsion pipe is fitted to the outside of the cable from a cut end, and the propulsion device adds the propulsion pipe to the inside of the pipeline while adding the propulsion pipe. The underground cable is characterized in that the power cable fixed to the pipeline is peeled off from the pipeline by a scraper or bit provided at the tip of the leading propulsion pipe and then the power cable is pulled out from the pipeline. Removal method. 2. The underground cable removing method according to claim 1, wherein the propulsion pipe is pushed into the conduit while rotating, and the cable fixing portion is cut off with a scraper or a bit at the tip of the leading propulsion pipe. 3. A universal joint capable of transmitting a rotational force is provided in the middle of the propulsion pipe or at a connection portion thereof, and the propulsion pipe added is bent along the pipe while being pushed into the pipe having the bent portion. 3. The method according to claim 1, wherein the underground cable is removed. 4. The underground cable removal method according to claim 1, wherein a tension is applied to the power cable on the pushing side while the propulsion pipe is being pushed.