JP2001221393A - Damage predicting method for underground buried pipe and damage predicting sensor for underground buried pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for predicting damage before an adjacent buried pipe is damaged when a sand blast phenomenon is generated caused by water leakage from a water pipe. SOLUTION: A rubber plate 3 for preventing mechanical damage is wound on a gas pipe 2 buried near a service water pipe 1, and a damage predicting sensor 4 is provided on it in the direction to face the service water pipe 1. A lead wire 5 of the damage predicting sensor 4 is drawn into a box 6 provided on the road source to always or periodically monitor the situation of the damage predicting sensor 4 from the ground. When sand blast 7 is occurred caused by the water leakage of damaged service water pipe 1, the damage predicting sensor 4 detects thereof. The situation of the damage predicting sensor 4 is always or periodically monitored from the ground, and therefore, possibilities of damage of the gas pipe 2 can be predicted before the sand blast 7 affects the gas pipe 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing a buried pipe disposed near a water pipe provided underground from being worn and damaged by a sandblast phenomenon caused by water leakage from the water pipe. The present invention relates to a prediction method and a sensor used for the method.

[0002]

2. Description of the Related Art Underground pipes, such as gas pipes and water pipes, which are buried underground, are often installed so as to run in the same place in parallel. Especially in urban areas, these plumbing
It is common to lay under the sidewalk parallel to the sidewalk, branch from it, and draw in each home. These pipes are often installed close to each other because their installation places are limited. For example, when a gas pipe and a water pipe are laid in parallel, it is not uncommon for the interval to be 10 cm or less.

[0003]

When a pipe such as a gas pipe is laid in parallel with a water pipe, when the water pipe is broken, water leakage may damage the pipe. That is, the sand used for backfill fluidizes and moves due to water leakage from the water pipe, and the sand blast phenomenon occurs when the sand collides with the pipe, causing the pipe to be worn. At this time, the fluidized sand does not flow away with water leakage, but flows convectionly between the water pipe and the pipe, hits the pipe many times, and wears the pipe due to sandblasting.

[0004] In order to protect the piping from such a sandblast phenomenon and other mechanical forces, in the case of a gas pipe, a rubber plate is wound around the gas pipe to protect the gas pipe. I have. However, once the above-mentioned sandblast phenomenon occurs, it cannot be prevented by such a rubber plate.

[0005] As described above, when the water pipe is provided in parallel with the water pipe, if water leaks from the water pipe, the gas pipe may be worn due to sandblasting, and a hole may be opened and gas may flow out. There is. Even if a hole is formed in the gas pipe, it is unlikely that an accident will occur because the surroundings of the gas pipe are usually covered with soil, but such a thing is not preferable in terms of safety.

[0006] The present invention has been made in view of such circumstances, and in the case where a sandblast phenomenon occurs due to water leakage from a water pipe, a method of predicting the damage before the adjacent buried piping is damaged. And a sensor used for the same.

[0007]

A first means for solving the above-mentioned problem is that an underground pipe installed close to a water pipe provided underground prevents leakage from the water pipe. A method for predicting damage due to a sandblast phenomenon caused by the above, wherein a sensor for detecting the occurrence of the sandblast phenomenon is embedded at least on the water pipe side of the underground pipe, and the sandblasting is performed by this sensor. A method for predicting damage to an underground pipe by detecting occurrence of a phenomenon and predicting damage to the underground pipe (claim 1)
It is.

In this means, since a sensor for detecting the occurrence of the sandblast phenomenon is buried at least on the side of the water pipe of the underground pipe, when the sandblast phenomenon occurs, the underground pipe is affected. Before the occurrence of the sandblast phenomenon can be predicted. Therefore, it is possible to quickly repair a damaged portion of the water pipe, so that it is possible to prevent damage to the buried pipe close to the water pipe.

[0009] A second means for solving the above-mentioned problems is as follows.
A sensor used in the first means, wherein a conductor is embedded in a zigzag or spiral shape so as to cover almost the entire surface of the insulator in a plate-shaped insulator which is easily worn by a sandblast phenomenon. A damage prediction sensor for a buried underground pipe (claim 2).

In this means, when the sandblast phenomenon occurs, the insulator is worn and damaged, and the conductor embedded therein is disconnected. Therefore, the occurrence of the sandblast phenomenon can be detected by constantly or periodically monitoring the conduction of the conductor. Note that “to cover almost the entire surface of the insulator” does not mean that the surface of the insulator is covered without a gap, but covers the insulator in a zigzag or spiral shape at a certain interval. This means that the conductor extends over almost the entire area of the insulator, so that the conductor can be disconnected even if any part of the insulator is damaged.

A third means for solving the above-mentioned problem is as follows.
The second means, wherein the zigzag or spiral interval of the embedded conductor is 10 mm or less (Claim 3).

According to experiments by the inventors, it has been found that the minimum range in which the sandblast phenomenon occurs is about 10 mmφ. Therefore, the distance between the embedded conductors is 10 mm.
The following can reliably detect the occurrence of the sandblast phenomenon.

A fourth means for solving the above-mentioned problem is as follows.
Either the second means or the third means, wherein an adhesive is provided on one surface of the plate-shaped insulating plate (claim 4).

In this means, the sensor can be bonded and fixed to the buried pipe by using an adhesive provided on one side of the plate-shaped insulating plate. At this time, it is easy to apply the adhesive on the side opposite to the insulating plate side by peeling off release paper etc., peeling it off at the time of construction to expose the adhesive, and attaching it to the piping is there.

[0015] A fifth means for solving the above problems is as follows.
A sensor used in the first means, wherein most of the planar conductor is wrapped with an insulator which is easily worn by sandblasting, and is buried underground. This is a tube damage prediction sensor (claim 5).

In this means, a lead wire connected to the conductor is pulled out to the ground, and the ground resistance of the conductor is observed. In a normal state, the ground resistance is high because most of the conductor is covered with the insulator. However, when the insulator is damaged by the sandblast phenomenon, a part of the conductor is grounded through the part, and the ground resistance is reduced. Therefore, the occurrence of the sandblast phenomenon can be detected by constantly or periodically monitoring the ground resistance of the conductor.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows Embodiment 1 of the present invention.
It is a figure which shows the installation situation of the apparatus used for the damage prediction method of the underground pipe which is an example. In FIG. 1, 1 is a water pipe, 2 is a gas pipe, 3 is a rubber plate, 4 is a loss prediction sensor, 5 is a lead wire, 6 is a box, and 7 is sandblast.

A rubber plate 3 is wound around the gas pipe 2 buried in the vicinity of the water pipe 1 so as to prevent mechanical damage. A prediction sensor 4 is provided. Damage prediction sensor 4
The lead wire 5 is drawn into a box 6 provided on the road surface, so that the condition of the damage prediction sensor 4 can be constantly or periodically monitored from the ground.

When the water pipe 1 is damaged and water leaks, and a sandblast 7 is generated due to the water leak, the damage prediction sensor 4 detects this. Therefore, by monitoring the condition of the damage prediction sensor 4 from the ground constantly or periodically, it is possible to predict the possibility of damage to the gas pipe 2 before the sandblast 7 affects the gas pipe 2.

FIG. 2 is a schematic view showing an example of a sensor for predicting breakage of an underground pipe according to an embodiment of the present invention. In the following drawings, the same components as those shown in the preceding drawings are denoted by the same reference numerals, and description thereof will be omitted. Of FIG.
(a) is a front view, (b) is an AA ′ cross-sectional view, and (a ′) is another front view. 8 is a copper wire as a conductor, 9 is polyethylene as an insulator, 10 is an adhesive, and 11 is a release paper.

In order to arrange the damage prediction sensor 4 along the gas pipe, the release paper 11 is peeled off to expose the adhesive 10, and the adhesive 10 is pressed against the gas pipe.
The damage prediction sensor 4 is attached along the outer surface of the gas pipe so as to cover the gas pipe. The distance between the copper wires 8 arranged in a zigzag shape is about 9 mm, and the thickness of the polyethylene 9 and the thickness of the adhesive 10 are both 1 mm.

When the sand blast phenomenon occurs, sand collides with the surface of the polyethylene 9 and scrapes the polyethylene 9 to cut the copper wire 8. Therefore, the copper wire 8
The occurrence of the sandblast phenomenon can be detected by the absence of continuity between the lead wires 5 drawn from both ends.

In FIG. 2, (a) shows the copper wires 8 arranged in a zigzag pattern, while (a ') shows the copper wires 8 arranged in a spiral. The spacing between the spirals is about 9 mm. Such a device also has the same action as that shown in FIG.

FIG. 3 shows a schematic diagram of another example of a sensor for predicting damage to an underground pipe according to an embodiment of the present invention. FIG.
In FIG. 1, (a) is a front view, (b), (b ′) are AA ′ cross-sectional views, 12 is a thin steel plate as a conductor, and 13 is a rubber as an insulator.

In this embodiment, as shown in the sectional view (b), the thin steel plate 12 is completely covered with the rubber 13, and as shown in FIG. 5, or as shown in the cross-sectional view (b '), the thin steel plate 12 is put in the rubber 13 and supported by the hollow rubber 13,
The structure is such that the lead wire 5 extends from a part thereof.

When using this damage prediction sensor,
One lead wire 5 is pulled out to the ground, and the ground resistance of this lead wire is constantly or periodically measured. When the sand blast phenomenon occurs, the rubber 13 is worn by the sand and a hole is opened. Then, the ground resistance of the thin steel plate 12 and the underground decreases, so that the occurrence of the sandblast phenomenon can be detected. In this case, the ground resistance does not increase so much even if there is no rubber at the portion C in FIG.

In the case of the cross-sectional structure as shown in (b), since only a decrease in the grounding resistance according to the damaged area of the rubber 13 is observed, there is a possibility that the detection sensitivity cannot be sufficiently obtained.
When a cross-sectional structure as shown in FIG.
Even if a part of the ground is damaged, the ground resistance decreases rapidly due to water entering inside. The reduction rate of the ground resistance depends on the area of the thin steel sheet 12, and the larger the area, the larger. Therefore, in FIG.
The area of the central thin steel sheet 11 supported by the support part 3 is:
It is preferably 200 cm ² or more.

[0028]

As described above, according to the present invention,
When sandblasting occurs, it is possible to predict the occurrence of the sandblasting before the underground pipe is affected.

[Brief description of the drawings]

FIG. 1 is a diagram showing an installation state of equipment used for a method of predicting damage to an underground pipe as an example of an embodiment of the present invention.

FIG. 2 is a diagram showing an outline of an example of a sensor for predicting breakage of an underground pipe as an embodiment of the present invention.

FIG. 3 is a diagram showing an outline of another example of a sensor for predicting breakage of an underground pipe according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Water pipe 2 ... Gas pipe 3 ... Rubber plate 4 ... Breakage prediction sensor 5 ... Lead wire 6 ... Box 7 ... Sand blast 8 ... Copper wire 9 ... Polyethylene 10 ... Adhesive 11 ... Release paper 12 ... Thin steel plate 13 ... Rubber

Claims (5)

[Claims] 1. A method for predicting that an underground pipe installed close to a water pipe installed underground is damaged by a sandblast phenomenon caused by leakage from the water pipe. A sensor for detecting the occurrence of the sandblast phenomenon is embedded at least on the water pipe side of the underground pipe, and the occurrence of the sandblast phenomenon is detected by this sensor to predict the damage of the underground pipe. A method for predicting damage to an underground pipe. 2. A sensor for use in the method for predicting breakage of an underground pipe according to claim 1, wherein a substantially whole surface of the insulator is covered by a plate-like insulator which is easily worn by sandblasting. A sensor for predicting breakage of an underground pipe, comprising a conductor embedded in a zigzag or spiral shape. 3. The underground buried pipe damage detection sensor according to claim 2, wherein a zigzag or spiral interval of the buried conductor is 10 mm or less. Damage prediction sensor. 4. An underground pipe according to claim 2 or 3, wherein an adhesive is provided on one surface of said insulating plate. Damage prediction sensor. 5. A sensor used in the method for predicting breakage of an underground pipe according to claim 1, wherein most of the planar conductor is wrapped with an insulator which is easily worn by sandblasting. A sensor for predicting breakage of underground pipes, comprising: