JPH09219917A - Underground conduit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an embedded conduit difficult to be damaged by absorbing the displacement even when the displacement in the axial direction and in the direction orthogonal to the axial direction is applied due to the displacement of the ground. SOLUTION: Non-expandable pipes 1 such as straight pipes and corrugated pipes embedded underground are connected to each other through a bellows pipe 2 capable of keeping its shape in the expanded condition and the contracted condition in the axial direction. The bellows pipe 2 is installed in the condition having both an expanded part 2a and a contracted part 2b. The displacement in the axial direction can be absorbed by contraction or expansion of the bellows pipe 2. The displacement in the direction orthogonal to the axis of the conduit can be absorbed by the bend of the bellows pipe 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underground buried pipeline used for laying cables underground.

[0002]

2. Description of the Related Art An underground buried pipeline is generally constructed by burying a straight pipe made of metal or plastic or a corrugated pipe made of plastic in the ground along a predetermined route. A work box such as a manhole or a handhole is provided in the middle of the pipeline to connect cables. In the case of a straight pipe, since it is not flexible and the length of one piece is short, there are many connection points. In the case of a corrugated pipe, since it is flexible and can be coiled and transported, the length of one pipe can be increased and the number of connection points can be reduced. Further, in the case of a corrugated pipe, bending and laying is easy.

[0003]

When a conventional underground buried pipeline is subjected to ground vibration or displacement, such as vibration or ground subsidence due to an earthquake, liquefaction of soil, or uneven subsidence due to normal load, It is easy for the pipe to crack, the pipe joint or the pipe to come off, and the pipe to work box connection to break. This is because the conventional underground buried pipeline can hardly cope with displacement in the pipe axis direction (expansion and contraction) and displacement in the direction perpendicular to the pipe axis (displacement of the pipe axis). Since the corrugated pipe is flexible, it can withstand the vibration of the ground and the bending of the pipeline to some extent, but since it has almost no elasticity in the pipe axis direction, it is almost forceless for displacement in the pipe axis direction. is there.

To solve this problem, it has been proposed to use universal joints and expansion joints at the connecting portions between pipes and pipes and work boxes. However, the universal joint can cope with vibration, but is ineffective against displacement of the pipe axis, particularly displacement (expansion and contraction) in the pipe axis direction. Further, since the expansion joint has a structure in which the sleeve is doubled, it can follow the displacement in the pipe axis direction, but cannot respond to the displacement in the direction perpendicular to the pipe axis.

In view of the above problems, an object of the present invention is to bury underground pipes that are not easily damaged even if displacement in the pipe axis direction or displacement in the direction perpendicular to the pipe axis occurs due to vibration or displacement of the ground. To provide a path.

[0006]

In order to achieve this object, in the underground buried pipeline of the present invention, a part or all of the tube buried in the ground is shrunk to the shape when extended in the axial direction. It is characterized in that it is composed of a bellows tube that can hold the shape of itself.

When the bellows tube as described above is installed in an expanded state, it can cope with a displacement which shrinks mainly in the axial direction of the tube, and when installed in a contracted state, it can cope with a displacement which mainly stretches in the axial direction of the tube. If it is installed in a state that it has both a bent portion and a contracted portion, it is possible to cope with the displacement extending in the pipe axis direction and the contracting displacement. Therefore, the bellows tube is in a stretched state mainly in a location where a contraction in the tube axis direction is expected to be extended, and in a retracted state mainly in a location where a displacement that is expected to extend in the tube axis direction is contracted, and a displacement that expands and contracts in the tube axis direction. Both are expected to be installed with both extended and contracted parts.

Further, since the elastic bellows tube is easily bent, it is possible to sufficiently cope with the displacement in the direction perpendicular to the tube axis (displacement of the tube axis). Further, the bellows tube used in the present invention can self-hold the two shapes of the expanded state and the contracted state, so that it is not necessary to apply a compressive force or a tensile force in the axial direction of the pipe when it is buried in the ground, Easy installation work.

From the economical viewpoint, it is preferable that the bellows pipe having the shape-retaining property as described above is partially installed in the underground buried conduit of the present invention, not in its entire length. In that case, the underground buried pipeline according to the present invention is used as a non-stretchable pipe (such as a straight stretchable pipe or a corrugated pipe buried in the ground, which includes difficult stretchability, the same applies hereinafter) or a non-stretchable pipe. It is preferable that a work box such as a manhole or a handhole is connected via a bellows tube capable of self-holding the shape when extended in the tube axis direction and the shape when contracted.

In this case, the bellows tube is installed in a state having both an extended part and a contracted part so that the bellows tube can cope with a displacement that extends in the pipe axis direction and a displacement that contracts in the pipe axis direction. It is preferable to do so.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1] FIGS. 1 to 3 show an embodiment of the present invention. In this embodiment, a non-stretchable pipe 1 such as a straight pipe or a corrugated pipe buried in the ground is provided with a bellows pipe 2 capable of self-holding a shape when extended in a pipe axis direction and a shape when contracted. Connected. Reference numeral 3 is a non-stretchable tube 1.
It is a pipe joint that connects the bellows pipe 2 with the. 1 shows a state where the bellows tube 2 is extended, FIG. 2 shows a state where the bellows tube 2 is contracted, and FIG. 3 shows a state where the bellows tube 2 has an extended portion 2a and a contracted portion 2b.

The bellows tube 2 is formed as shown in FIG. 1 so that the bellows tube 2 can hold the shape when it is stretched and the shape when it is contracted. That is, each corrugation forming the bellows has a length G from the top of the mountain to the bottom of one of the valleys,
It is formed so that the length H to the bottom of the other valley is different (serrated). In other words, the angle θg formed by the surface perpendicular to the pipe axis passing through the top of the mountain and one slope g is formed larger than the angle θh formed by the vertical surface and the other slope h (that is, the bellows pipe 2 extends). In this state, the angles θh and θg formed by the slopes h and g with respect to the plane perpendicular to the tube axis are different, and the angle θg formed by the longer slope g is larger.
The angle θh formed by the shorter slope h is not 0 °. ). The diameter of the top of the peak and the diameter of the bottom of the valley are constant for each waveform. With such a shape, the bellows tube 2 maintains its shape stably with the long slope g and the short slope h on both sides of the top of the mountain (extended state) as shown in FIG. As long as possible, the short slope h is long and the long slope g is long as shown in FIG.
The shape can be stably maintained even when it is inside (shrinked). Therefore, the stretched state and the contracted state can be self-maintained.

The bellows pipe 2 is stretched as shown in FIG. 1 at the end of the non-stretchable pipe 1 at a position where the distance between the ends of the non-stretchable pipe 1 is expected to be reduced due to the displacement of the ground. Connect between. By doing so, the contraction of the end-to-end distance of the non-stretchable tube 1 can be absorbed until the bellows tube 2 becomes the state of FIG. Further, since the bellows tube 2 can be slightly extended from the state shown in FIG. 1, it is possible to cope with a slight extension of the distance between the ends of the non-stretchable tube 1. Furthermore, since the bellows tube 2 in the state shown in FIG. 1 can be easily bent, the non-stretchable tubes 1, 1
It is also possible to absorb the deviation of the tube axis.

The bellows tube 2 is contracted as shown in FIG. 2 at the end of the non-stretchable tube 1 at a location where the distance between the ends of the non-stretchable tube 1 is expected to increase due to the displacement of the ground. Connect departments. By doing so, the extension of the end-to-end distance of the non-stretchable tube 1 can be absorbed until the bellows tube 2 reaches the state shown in FIG. Further, since the bellows tube 2 can be slightly contracted from the state shown in FIG. 2, it is possible to cope with a slight contraction of the distance between the end portions of the non-stretchable tube 1. Further, since the bellows tube 2 in the state shown in FIG. 2 is easily bent, the non-stretchable tubes 1, 1
It is also possible to absorb the deviation of the tube axis.

Further, the bellows tube 2 contracts with the extended portion 2a as shown in FIG. 3 at a place where it is expected that the distance between the ends of the non-stretchable tube 1 will be reduced or increased due to the displacement of the ground. The ends of the non-stretchable tube 1 are connected to each other with both of the portions 2b. By doing so, it is possible to absorb the extension of the distance between the end portions of the non-stretchable tube 1 until the bellows tube 2 reaches the state of FIG. 1 and until the bellows tube 2 reaches the state of FIG. The contraction of the distance between the ends of the non-stretchable tube 1 can be absorbed. Further, since the bellows tube 2 in the state shown in FIG. 3 is easily bent, it is possible to absorb the deviation of the tube axes of the non-stretchable tubes 1 and 1.

[Second Embodiment] FIG. 4 shows another embodiment of the present invention. In this embodiment, a work box 4 such as a manhole or a handhole and a non-stretchable tube 1 are connected via the same bellows tube 2 used in the first embodiment. The bellows tube 2 is installed in the state shown in FIG. 1, FIG. 2 or FIG. 3 and can absorb expansion or contraction in the tube axis direction or deviation of the tube axis as in the first embodiment. Also bellows tube 2
Is bendable, the two can be connected even when the axis of the non-stretchable tube 1 is inclined with respect to the axis of the connection port of the work box 4, as shown on the left side of FIG.

[Other Embodiments] FIG. 5 shows a non-stretchable tube 1
And the bellows tube 2 are separately manufactured, and the non-stretchable tube 1 and the bellows tube 2 are alternately connected to form an underground buried pipeline. The first embodiment is of this type. The bellows tube 2 can be manufactured by an injection molding method or a blow molding method. The connection between the non-stretchable tube 1 and the bellows tube 2 was performed by the pipe joint in the first embodiment, but the fitting portions with the non-stretchable tube 1 are formed at both ends of the bellows tube 2 by fitting them. It can be carried out, or it can be carried out by adhesion or fusion. The plurality of bellows tubes 2 alternate,
It is good to keep it in a stretched state and in a contracted state.

FIG. 6 shows an example in which a bellows tube 2 is integrally formed at one end of a non-stretchable tube 1 having an appropriate length, which is connected in the longitudinal direction to form an underground buried pipeline. is there. The non-stretchable tube 1 and the bellows tube 2 can be connected by the same means as in the case of FIG.

FIG. 7 shows an example in which a non-stretchable tube 1 and a bellows tube 2 are alternately integrally molded to form a buried underground pipeline. In order to alternately form the non-stretchable tube 1 and the bellows tube 2 integrally with each other, the bellows tube 2 is formed by a press molding method or the like for each length while continuously manufacturing the non-stretchable tube 1 by an extrusion molding method. Good.

FIG. 8 shows an example in which the present invention is applied to a pipeline drawn from the building 5 to the ground. In this example, the portion having a predetermined length from the portion penetrating the underground outer wall 5a of the building toward the outside is the bellows tube 2 capable of self-holding both the extended shape and the contracted shape. The bellows tube 2 is constructed in a contracted shape. With this arrangement, when the outer non-stretchable pipe 1 is lowered relative to the building 5 due to ground subsidence, the portion of the bellows pipe 2 is stretched and bent to absorb the influence of ground subsidence. It is possible to prevent damage to underground buried pipelines.

[0021]

As described above, according to the present invention, by using a bellows tube capable of self-holding the shape when it is extended in the axial direction and the shape when it is contracted, in part or all of the conduit. Even when a displacement in the pipe axis direction or a displacement in a direction perpendicular to the pipe axis is applied due to the displacement of the ground, it is possible to absorb those displacements and obtain an underground buried pipeline that is not easily damaged.
Further, since the bellows tube has a simple structure, there is an advantage that the manufacturing cost is low.

[Brief description of drawings]

FIG. 1 shows an embodiment of an underground buried pipeline according to the present invention,
The front view of the half incision shown with the bellows tube extended.

FIG. 2 shows an embodiment of an underground buried pipeline according to the present invention,
The front view of the half incision shown with the bellows tube contracted.

FIG. 3 shows an embodiment of an underground buried pipeline according to the present invention,
The half-incision front view shown in the state which the bellows tube has the extended part and the contracted part.

FIG. 4 is a plan view showing another embodiment of the underground buried pipeline according to the present invention.

FIG. 5 is an explanatory view showing still another embodiment of the underground buried pipeline according to the present invention.

FIG. 6 is an explanatory view showing still another embodiment of the underground buried pipeline according to the present invention.

FIG. 7 is an explanatory view showing still another embodiment of the underground buried pipeline according to the present invention.

FIG. 8 is an explanatory view showing still another embodiment of the underground buried pipeline according to the present invention.

[Explanation of symbols]

 1: Non-stretchable pipe such as straight pipe or corrugated pipe 2: Bellows pipe 3: Pipe fitting 4: Work box such as manhole or handhole

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shozo Yano 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (3)

[Claims] 1. A part or all of a pipe buried underground,
An underground buried pipeline characterized by being constituted by a bellows pipe (2) capable of self-holding a shape when extended in an axial direction and a shape when contracted. 2. Non-stretchable pipes (1) embedded in the ground (including hard-to-stretch, same below) or non-stretchable pipes (1) and work boxes (4) such as manholes and handholes. ) Is connected via a bellows pipe (2) capable of self-holding a shape when extended in the axial direction and a shape when contracted in the axial direction. 3. The underground buried pipeline according to claim 2, wherein the bellows tube (2) is installed in a state having both an extended portion (2a) and a contracted portion (2b).