JP2002238140A - Buried conduit line and its installation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid a movement of a power cable retained in a unit conduit 1. SOLUTION: A cable is retained in a first unit conduit 1 and a second unit conduit 1. The tip of the first unit conduit 1 is coupled with one side inner diameter of a outer cylinder 3, and the tip of the second unit conduit 2 is inserted into the other side inner diameter of the outer cylinder 3. A junction reinforcing part 2 reinforces unifying of the first and second unit conduits 1 and 1 adjacent to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable buried conduit and a method of burying the cable.

[0002]

2. Description of the Related Art Power cables are often laid in buried conduits below roadways. In such a case, it is well known that the power cable moves in the traveling direction of the vehicle traveling thereon. This phenomenon is usually called a surfing phenomenon, and appears remarkably when laid on soft ground and in a place with a large traffic volume. This surfing phenomenon is considered to be caused by the vibration of the vehicle running on the road. A conventional method for eliminating the surfing phenomenon will be described with reference to the drawings.

FIG. 8 is a diagram showing the principle of the conventional cable movement elimination. FIG. 4 is a cross-sectional view of a buried pipeline explaining one method for eliminating a surfing phenomenon of a power cable 30 laid in the pipeline.

[0004] As shown in FIG. 8, in the conventional buried pipeline, the restraint device 34 is fixed on the outer layer of the power cable 30 near the pipeline opening of the manhole. When the power cable 30 attempts to move, the restraint device 34 is restrained by the tip of the buried conduit 32, and the movement is stopped. That is, the above-described method employs a method in which the thrust in the length direction of the power cable 30 generated by the surfing phenomenon is eliminated by the restraint device 34 without dealing with the surfing phenomenon itself.

[0005]

However, the above-mentioned prior art has the following problems to be solved. Since the above method does not deal with the surfing phenomenon itself, the force concentrates on the restraint device 34. Therefore, there is a case where a problem that cannot be predicted in advance occurs at a portion of a long span where the distance between adjacent manholes is large.

[0006]

Means for Solving the Problems <Structure 1> A buried conduit in which a plurality of pipes holding a cable therein are joined in series, and provided at one end of the pipe and adjacent to the pipe. A buried conduit, comprising: an outer cylinder into which a distal end of a pipe alone is inserted; and a joint reinforcing portion that includes the outer cylinder and reinforces a joint with the adjacent pipe alone.

<Structure 2> The buried conduit according to Structure 1, wherein the adjacent pipes are fixed to each other with an adhesive at the joint reinforcing portion.

<Structure 3> A buried conduit according to Structure 2, wherein the adhesive is concrete or epoxy resin.

<Configuration 4> Any one of Configurations 1 to 3
7. The buried pipeline according to claim 1, wherein a tip of the adjacent pipe unit is supported by a ring disposed on an inner surface of the outer cylinder in a longitudinal direction of the cable. .

<Configuration 5> Any one of Configurations 1 to 3
In the buried conduit described in the paragraph, the distal end of the adjacent pipe unit is supported by a group of protrusions separately arranged on the inner surface of the outer cylinder in the length direction of the cable 45. Pipeline.

<Structure 6> In the buried conduit described in Structure 1, the joint reinforcing portion has a semi-cylindrical bend that integrates the adjacent pipe unit with the outer cylinder sandwiched from the radial direction of the outer cylinder. A buried conduit characterized by being constituted by a stopper reinforcement.

<Structure 7> A method of laying a buried conduit in which a plurality of pipes holding a cable inside are joined in series, wherein the polymer mat is any one of Structures 1 to 5.
13. A method of laying a buried pipeline, wherein the method is arranged in contact with the outer diameter of the buried pipeline described in the above item.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The prior art described above eliminates the thrust in the length direction of the power cable 30 generated by the surfing phenomenon by the restraint device 34 (FIG. 8) without dealing with the surfing phenomenon itself. In contrast, the present invention aims to eliminate the surfing phenomenon itself.

Hereinafter, embodiments of the present invention will be described with reference to specific examples. <Embodiment 1> FIG. 1 is a structural view of a buried conduit according to Embodiment 1. (A) is an overall configuration diagram, and (b) is an enlarged view of a portion A in which only a joint portion of a pipe alone is enlarged. Figure 1
From (a), the buried conduit according to the specific example 1 includes a single pipe (first single pipe) 1, a single pipe (second single pipe) 1, a coupling reinforcing portion 2, and an outer cylinder 3. . As shown in FIG.
Is provided with a polymer cylinder 4 therein.

Before describing the details of the buried pipeline according to the first embodiment, the configuration of the underground power system constituted by the buried pipeline will be described. FIG. 2 is an underground power system configuration diagram. As shown in FIG. 2, the underground power system includes a pipeline 23 in which pipes 1 each having a total length of about 3 meters that hold a cable therein are continuously connected in series, and a ground 23 for maintenance and management of the pipeline 23. It is constituted by a manhole 21 which is a point of contact with the pipe 23. Usually, the distance between adjacent manholes is about 100 to 300 meters.

Next, the relationship between the underground power system and the road will be described with reference to the drawings. FIG. 3 is a diagram showing the relationship between the roadway and the underground power system. (A) is a side sectional view of a roadway and an underground power system. (B) is a front sectional view of a roadway and an underground power system. As shown in FIG.
An underground power system 25 is arranged at a position of about a meter.
The underground power system 25 includes a plurality of pipelines 23 that hold a power cable 30 therein.

The cause of the surfing phenomenon in the underground power system described above is assumed as follows. Assumption 1 FIG. 4 is an explanatory diagram (part 1) of the surfing phenomenon. Roadway 24
When the vehicle 26 travels above, a Rayleigh wave (surface acoustic wave) is generated in the traveling direction of the vehicle. The individual pipes 1 buried in the ground surface and shorter than the wavelength of the Rayleigh wave also individually perform elliptical movements following the Rayleigh wave. As a result, a thrust in the traveling direction of the vehicle acts on the power cable 30 held inside the pipeline, and the power cable 30 moves.

This phenomenon will be described using an ultrasonic (surface wave) linear motor as an example. In an ultrasonic (surface acoustic wave) linear motor, when a surface acoustic wave is excited in a driver formed of a long strip of elastic material, a moving element in contact with the driver receives a thrust in the traveling direction of the surface acoustic wave. Move. In this case, if the surface acoustic wave is reflected at, for example, the tip of the driver, the elastic wave on the driver becomes a standing wave and is no longer a traveling wave, and the thrust disappears. However, the underground power system has a long manhole interval of 100 to 300 meters. Therefore, since the attenuation of the Rayleigh wave (surface acoustic wave) is large during that time, it is difficult to imagine the generation of a standing wave. As a result, thrust is generated. Here, the Rayleigh wave (surface acoustic wave) is a wave obtained by combining a longitudinal wave and a transverse wave, and is an elastic wave transmitted on the ground surface during an earthquake.

Assumption 2 FIG. 5 is an explanatory view of a surfing phenomenon (No. 2). A phenomenon has been discovered in which, when a synthesized longitudinal wave mixed from a large amplitude to a small amplitude advances, a large-amplitude wave becomes faster than a small-amplitude wave. One example is when the waves hitting the shore break white.

This is because the speed of the leading edge (maximum amplitude wave) of the approaching wave is faster than that of the small amplitude wave. In this case, a thrust is generated in the traveling direction of the wave while being a simple longitudinal wave. One example of application of this thrust is surfing (surfing). This wave is usually called a soliton wave,
In recent years, it has been spotlighted in optical communication technology and the like. In the present invention, it is expressed as an elastic wave propagating in a solid.

In the above-mentioned surfing phenomenon, since the vehicle travels right above the pipeline, a combined longitudinal wave mixed from a large amplitude to a small amplitude advances. Therefore, it is highly probable that the surfing phenomenon is caused by a composite longitudinal wave mixed from the large amplitude to the small amplitude.

The inventor of the present application has assumed the cause of the surfing phenomenon 1
The present invention is configured as follows, assuming one or both of the above and Assumption 2. Returning to FIG. 1, the first example will be described.

The tube unit (first tube unit) 1 is a portion that holds a power cable therein and is buried underground to form a conduit. Usually, the pipe is made of a polymer material, reinforced concrete, asbestos, steel pipe or the like having an outer diameter of 10 cm or less and a total length of several meters or less.

The pipe unit (second pipe unit) 1 is a part that holds a power cable inside and is buried underground to form a pipe line. Usually, the pipe is made of a polymer material, reinforced concrete, asbestos, steel pipe or the like having an outer diameter of 10 cm or less and a total length of several meters or less.

The joint reinforcing portion 2 is a portion for reinforcing the integration of the first tube unit and the second tube unit adjacent to each other with the outer tube 3 described later interposed therebetween. Normally, concrete or epoxy-based adhesive is injected around the outer cylinder 3 and the adjacent first and second pipes are fixed to each other.

The outer tube 3 has one inner diameter fitted with the tip of the tube unit 1 (first tube unit), and the other inner diameter inserted with the second tube unit via the rubber tube. Part.
In many cases, it is often made of the same material as the single pipe (first pipe) 1 and the single pipe (second pipe) 1. However, a single pipe (first single pipe) 1 and a single pipe (second single pipe) 1
A different material may be used. Alternatively, the single tube (first tube) 1 and the single tube (second tube) 1 may be integrally formed of the same material.

The polymer tube 4 is a portion for absorbing the vibration between the above-mentioned single tube (first single tube) 1 and the single tube (second single tube) 1. It is usually made of a cylindrical rubber material, and is attached to the outer diameter portion at the tip of the pipe unit (second tube unit) 1. Depending on the application, several wedge-shaped grooves may be provided in the inner diameter portion.

By adopting the above configuration, the pipe unit 1 (first tube unit) and the tube unit (second tube unit) 1 constituting the pipe are equivalent to having the entire length increased. It can be assumed that it becomes difficult to individually follow the Rayleigh wave or the soliton wave. That is, the tube single 1 that is shorter than the wavelength of the Rayleigh wave or soliton wave propagating in the pipe line individually follows the Rayleigh wave or soliton wave individually, but is connected in series and equivalently has a longer overall length. In this state, it no longer follows the Rayleigh wave or the soliton wave.

In order to increase this effect, FIG.
As shown in (b), the outer tube 3 supports the tube unit (second tube unit) 1 with a ring-shaped projection provided inside the outer tube 3, a first support portion 5, and a second support. It may be supported by the part 6. That is, the outside of the tip of the adjacent pipe unit may be supported by two projections provided on the circumference of the outer cylinder 3 and provided separately in the length direction of the cable.
The projections need not be ring-shaped over the entire circumference, but may be, for example, a group of projections arranged on the circumference.

The inventor of the present application installed a vibrometer inside the pipe having the above configuration, and made the vehicle run immediately above the vibrometer. As a result, the vibration meter was larger than in the case where the configuration of this embodiment was not adopted. A significant difference could be detected. That is, the movement of the power cable held inside the pipeline was hardly detected.

<Specific Example 2> In the specific example 2, the above specific example 1
In order to further increase the effect of the above, the connection between the pipes is further strengthened. In order to achieve this object, the buried conduit according to the second embodiment is configured as follows.

FIG. 6 is a configuration diagram of a buried conduit according to the second embodiment. From FIG. 6, the buried conduit according to the specific example 2 includes a single pipe (first single pipe) 1, a single pipe (second single pipe) 1,
A polymer cylinder 2, an outer cylinder 3, a bending-reinforcing reinforcement 7, a bolt 8 and a nut 9 are provided.

The bending-preventing reinforcing member 7 integrally reinforces the single pipe (first single pipe) 1 and the single pipe (second single pipe) 1 by sandwiching the outer cylinder 3 from the radial direction. This is a semi-cylindrical metal fitting. The single pipe (first single pipe) 1, the single pipe (second single pipe) 1, and the outer cylinder 3 are enclosed by two bending-reinforcing reinforcements 7 and fastened by bolts 8 and nuts 9. The other components are exactly the same as those in the first embodiment, and thus the description is omitted.

In the buried conduit according to the second embodiment, by adopting such a configuration, the individual pipes 1 are more difficult to move individually, and the individual pipes 1 are less likely to follow Rayleigh waves or soliton waves. As a result, the power cable held inside the pipe unit 1 becomes difficult to move.
Note that the structure of the joint reinforcing portion 7 is not limited to the structure shown in FIG. That is, instead of the structure in which the two anti-bending reinforcements 7 shown in FIG. 6 are tightened with the bolts 8 and the nuts 9, for example, three or more circumferentially divided anti-bending reinforcements 7 are tightened with a ring. It may have a structure.

<Embodiment 3> This embodiment relates to the method of laying a buried conduit described in the embodiment 1 or 2. FIG.
FIG. 3 is an explanatory view of a pipeline laying method. In the pipeline laying method according to the present invention, at the bottom of a trench excavated to bury a pipeline,
First, the foundation sand 11 is laid. The purpose is to flatten the bottom of the groove. Next, a rubber mat 12 is laid on the foundation sand 11.

On the rubber mat 12, a plurality of conduits 23 for holding the power cables inside are arranged. In this state, the backfill sand 13 is laid to the upper surface of the pipeline 23. The rubber mat 12 is laid again on the upper surface of the pipe 23. A plurality of conduits 23 are arranged on the rubber mat 12.

In this state, the backfilled sand 13 is again filled with the pipe 23.
Lay down to the top of Finally, the local soil 14 is filled up to the ground. This specific example is different from the conventional laying method in that a polymer mat (rubber mat 1) that absorbs vibration propagating on the pipeline 23 is used.
2) is replaced by the pipe line 23 described in the specific example 1 or the specific example 2.
It is characterized in that it is arranged above and below and embedded.

The points to be noted here are as follows. In the specific examples 1 and 2, the plurality of pipes 1 (FIG. 1) are assumed to be prevented from individually performing an elliptical motion following a Rayleigh wave or a soliton wave.
(FIG. 1) was firmly connected to form a single tube having a long overall length equivalently.

In such a case, it can be assumed that the single tube 1 (FIG. 1) can be prevented from individually performing an elliptical movement following the Rayleigh wave or the soliton wave, but the following inconvenience occurs. That is, if the total length of the tube itself (equivalent total length) becomes longer than the wavelength of the Rayleigh wave or soliton wave,
There is a possibility of propagating inside the pipe alone (within the wall thickness of the pipe).

As a result, on the same principle as that of the ultrasonic (surface acoustic wave) linear motor of the assumption 1, the tube, which is firmly connected and equivalently elongated, serves as a driver. The power cable held in the tube itself acts as a moving element and moves by receiving a thrust in the traveling direction of the Rayleigh wave or soliton wave.

The rubber mat 12 plays the role of eliminating such inconvenience. A conduit 23 is placed on the rubber mat 12. Therefore, the vibration propagating in the pipe alone (within the thickness of the pipe) is absorbed. As a result, the power cable held by the pipe alone stops moving.

[0042]

As described above, by firmly connecting a plurality of pipes, the pipes are prevented from being individually moved by following the vibration excited by a vehicle running immediately above the pipes. I can do it. As a result, there is no movement of the power cable held inside the pipe alone.
Also, by laying the pipe on the rubber mat when laying the pipe, it is possible to absorb the vibration that is assumed to propagate inside the pipe itself (within the thickness of the pipe), so the power cable held inside the pipe alone Movement is lost.

[Brief description of the drawings]

FIG. 1 is a structural diagram of a buried pipeline according to a specific example 1.

FIG. 2 is an underground power system configuration diagram.

FIG. 3 is a diagram illustrating a relationship between a roadway and an underground power system.

FIG. 4 is an explanatory view (1) of a surfing phenomenon.

FIG. 5 is an explanatory view of a surfing phenomenon (No. 1).

FIG. 6 is a configuration diagram of a buried conduit according to a specific example 2.

FIG. 7 is an explanatory diagram of a pipe laying method.

FIG. 8 is a principle diagram of conventional cable movement elimination.

[Explanation of symbols]

 1 pipe alone (first pipe alone), pipe alone (second pipe alone) 2 joining reinforcement part 3 outer cylinder

Claims (7)

[Claims] 1. A buried conduit in which a plurality of pipes holding a cable therein are joined in series, provided at one end of the pipe, and the tip of an adjacent pipe is inserted. A buried conduit comprising: an outer cylinder; and a joint reinforcing portion that includes the outer cylinder and reinforces a joint between the adjacent pipe unit. 2. The buried conduit according to claim 1, wherein the adjacent pipes are fixed to each other with an adhesive in the joint reinforcing portion. 3. The buried pipeline according to claim 2, wherein the adhesive is concrete or epoxy resin. 4. The buried conduit according to claim 1, wherein a tip of the adjacent single pipe is separated from an inner surface of the outer cylinder in a length direction of the cable. A buried conduit characterized by being supported by an arranged ring. 5. The buried conduit according to claim 1, wherein a tip of the adjacent single pipe is separated from an inner surface of the outer cylinder in a length direction of the cable. A buried conduit characterized by being supported by a group of arranged projections. 6. The buried conduit according to claim 1, wherein the joint reinforcing portion is a semi-cylindrical bending stopper that integrates the adjacent pipe unit with the outer cylinder sandwiched from a radial direction of the outer cylinder. A buried conduit characterized by being constituted by a reinforcing tool. 7. A method for laying a buried conduit in which a plurality of pipes holding a cable therein are joined in series, wherein the polymer mat is according to any one of claims 1 to 5. A method of laying a buried conduit, wherein the method is arranged in contact with an outer diameter of the buried conduit.