JIG AND LAYING METHODS

Abstract

In order to solve the foregoing problems, an object of the present invention is to provide a jig and a laying method capable of laying a branch wire which can avoid a contact with a house or passersby and eliminating an unbalanced load of a utility pole erected in a confined area.

Description

TECHNICAL FIELD

The present disclosure relates to a jig attached to a utility pole and a method of laying a utility pole.

BACKGROUND ART

In the related art, laid utility poles have hollow interior and a tapered shape in a longitudinal direction, are made of metal materials or concrete materials, and are laid for the purpose of laying cables overhead.

For such a utility pole, there is a method of eliminating an unbalanced load generated by laying a cable or the like by sharing a reaction force of an unbalanced load with a branch wire, by bringing down a branch wire configured with a steel strands or the like from a specific portion lower than a top portion of a utility pole to the ground a given distance away from the utility pole, and fixing the branch wire to the ground by an anchor or the like (see, for example, Non Patent Literature 1).

CITATION LIST

Non Patent Literature

• • Non Patent Literature 1: “Shinai senro kensetsu koho (in Japanese) (City Track Construction Method)” published by Nippon Telegraph and Telephone Public Corporation, 4.6 Branch Wire and Utility Pole, 4.6.1 Overview

SUMMARY OF INVENTION

Technical Problem

However, the method of eliminating the unbalanced load has the following problems.

When s utility pole is erected, an anchor 16 or the like may be laid to fix the branch wire 15 to the ground 50. At this time, there is a limitation on a separation distance from the vicinity of the ground at a utility pole 10 to the anchor 16 (hereinafter referred to as base opening). Accordingly, as in FIG. 1, when the branch wire 15 is laid in a confined area where a laying range is limited by a house 20 or the like, there is a first problem that measures for avoiding a contact with the house 20 and a contact with passersby 5 is required.

In addition, there is a second problem that it is difficult to sufficiently obtain the effect of the branch wire such as elimination of an unbalanced load by reducing an attachment angle of the branch wire with respect to the utility pole by confining the base opening between the branch wire and the utility pole on which the branch wire needs to be laid.

In the related art, the foregoing problem has been solved by replacing a utility pole which is erected in such a confined area and in which an unbalanced load occurs with a strong utility pole (a self-supporting pole) that does not require a branch wire. However, the self-supporting pole has a problem that a unit price thereof is higher than that of a general utility pole and an erection cost thereof is high. A heavy machine or the like cannot enter a confined area due to the confined space in some cases. Since it is often necessary to rely on pole erection work by manpower, there is also a problem that it is necessary to pay attention to accidents such as a contact accident or damage to a surrounding house.

Accordingly, in order to solve the above problems, an object of the present invention is to provide a jig and a laying method capable of laying a branch wire which can avoid a contact with a house or a passersby and eliminating an unbalanced load of a utility pole erected in a confined area.

Solution to Problem

In order to achieve the above object, in a laying method according to the present invention, a jig that has a member for fixing a branch wire from a top portion of a utility pole (hereinafter referred to as the upper branch wire) and a member for fixing a branch wire (hereinafter referred to as a lower branch wire) on a ground side at a distal end of the member is fixed to the utility pole.

Specifically, a jig according to as aspect of the present invention is a rodlike jig of which one end is attached to a surface of a utility pole to be perpendicular to the utility pole. The jig includes:

a first member configured to hold an upper branch wire connected to a top portion of the utility pole at the other end; and a second member configured to hold a lower branch wire connected to a ground parallel with the utility pole.

A laying method according to the present invention is a laying method including:

• • attaching one end of a rodlike jig to a surface of a utility pole to be perpendicular to the utility pole;
  • connecting the other end of the jig to a top portion of the utility pole by an upper branch wire; and
  • connecting the other end of the jig to the ground with a lower branch wire so that the lower branch wire is parallel to the utility pole.

Since a first member of the jig is connected to a distal end of the utility pole by an upper branch wire and a second member of the jig is connected to the ground by a lower branch wire perpendicular to the ground, the utility pole can be laid in a confined area while securing an attachment angle of the upper branch wire with respect to the utility pole and eliminating an unbalanced load of the utility pole. By securing an optimum separation distance between the utility pole and the lower branch wire, a risk of contact with a house or passersby can be reduced.

Further, the jig according to the aspect of the present invention further includes an expansible mechanism that makes a length in a longitudinal direction variable

The laying method according to the aspect of the present invention may further include:

• • calculating an unbalanced load applied to the utility pole;
  • acquiring a relationship between a length of the jig in a longitudinal direction and a load amount generated in the upper branch wire;
  • finding the length of the jig for eliminating the unbalanced load from the relationship; and
  • setting the length of the jig attached to the utility pole to the length found from the relationship.

By attaching a variable mechanism capable of adjusting the length of the jig, it is possible to perform erection more flexibly in a confined area appropriate for a surrounding environment, and it is possible to implement long-term safe use of the utility pole and a reduction in a re-erection cost by eliminating an unbalanced load in the confined area which has not been able to be implement in the related art.

It is possible to combine the above inventions as far as possible.

Advantageous Effects of Invention

The present invention can provide a jig and a laying method capable of laying a branch wire which can avoid a contact with a house or passersby and can eliminate an unbalanced load of a utility pole erected in a confined area.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a branch wire laid in a confined area where an installation range is limited by a house or the like and is a diagram illustrating problems of the present invention.

FIG. 2 is a diagram illustrating a jig according to the present invention.

FIG. 3 is a diagram illustrating a jig according to the present invention.

FIG. 4 is a flowchart illustrating a laying method according to the present invention.

FIG. 5 is a diagram illustrating an advantageous effect of the jig according to the present invention.

FIG. 6 is a view illustrating an advantageous effect of the jig according to the present invention.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments to be described below are examples of the present invention and the present invention is not limited to the following embodiments. Components denoted by the same reference numerals in the present specification and the drawings indicate the same components.

Embodiment 1

FIGS. 2 and 3 are diagrams illustrating a jig 30 according to the present embodiment. The jig 30 is a rodlike jig in which one end 30a is attached to the surface of the utility pole 10 to be perpendicular to the utility pole 10, and includes, at the other end 30b, a first member 31 that holds an upper branch wire 15-1 connected to the top portion 10a of the utility pole 10 and a second member 32 that holds a lower branch wire 15-2 connected to the ground 50 in parallel with the utility pole 10.

The jig 30 has, at the other end 30b, the first member 31 for fixing the upper branch wire 15-1 and the second member 32 for fixing the lower branch wire 15-2. The jig 30 is formed of a metal material or the like and has a columnar or cylindrical shape such as a round shape or a square shape.

The jig 30 fixes one end 30a to the surface of the utility pole 10 such that the central axis of the jig 30 is perpendicular to the central axis of the utility pole 10. It is preferable to use a band 33 for fixing the jig 30. The first member 31 and the top portion 10a (a wire extension portion) of the utility pole 10 are connected by the upper branch wire 15-1, and the second member 32 and the ground 50 are connected by the lower branch wire 15-2 perpendicular to the ground 50 (parallel to the utility pole 10). By laying a branch wire using the jig 30, it is possible to lay the branch wire in a confined area while securing an attachment angle θ of the upper branch wire 15-1 with respect to the utility pole 10 and eliminating an unbalanced load of the utility pole 10. By separating the utility pole 10 and the lower branch wire 15-2 appropriately from each other, it is possible to secure a space A for passersby to walk or the like and to reduce a contact risk B with the house 20.

The jig 30 further includes an expansible mechanism 34 that has a variable length in the longitudinal direction. By using the expansible mechanism 34 capable of adjusting the length of the jig 30, it is possible to perform erection more flexibly in a confined area appropriate for a surrounding environment, and it is possible to implement long-term safe use of the utility pole and a reduction in a re-erection cost by eliminating the unbalanced load in the confined area which has not been able to be implemented in the related art.

Embodiment 2

FIG. 4 is a flowchart illustrating a procedure of the laying method according to an embodiment. The laying method includes:

• • attaching one end 30a of the jig 30 to the surface of the utility pole 10 so that the rodlike jig 30 is perpendicular to the utility pole 10 (step S01);
  • connecting the other end 30b of the jig 30 to the top portion 10a of the utility pole 10 by the upper branch wire 15-1 (step S02); and
  • connecting the other end 30b of the jig 30 to the ground 50 by a lower branch wire 15-2 so that the lower branch wire 15-2 is parallel to the utility pole 10 (steps S03 and S04).

Step S01: one end 30a of the jig 30 is fixed at a specific height from the ground of the utility pole 10.

Step S02: the upper branch wire 15-1 is stretched from the top portion 10a of the utility pole 10 (a wire extension portion: metal object for anchoring a cable or the like) to the other end 30b of the jig 30, and the jig 30 is horizontally fixed to the ground 50.

Step S03: the anchor 16 or the like is installed on the ground 50 around the utility pole 10.

Step S04: the lower branch wire 15-2 is stretched perpendicularly to the ground 50 from the other end 30b of the installed jig 30 and is fixed to the anchor 16 or the like.

Step S05: when the branch wire connected to the jig 30 is slackened, the advantageous effect of eliminating the unbalanced load is reduced, to adjust tension of the branch wire. Accordingly, a reaction force of the unbalanced load can be shared and eliminated.

Next, step S06 will be described. The length of the jig 30 is adjusted in accordance with magnitude of the unbalanced load applied to the utility pole. Step S06 is performed in the following procedure:

• • (Procedure 1) calculating the unbalanced load applied to the utility pole 10;
  • (Procedure 2) acquiring a relationship between the length of the jig 30 in the longitudinal direction and a load amount caused by the upper branch wire 15-1;
  • (Procedure 3) finding the length of the jig 30 that eliminates the unbalanced load from the relationship; and
  • (Procedure 4) setting the length of the jig 30 attached to the utility pole 10 to the length found from the relationship.

First, Procedure 1 will be described.

Tension T of a cable laid on the utility pole 10 during no wind is expressed by the following Expression (1).

$\left[\mathrm{Math}.1\right]$ $\begin{array}{cc}T=\frac{{\mathrm{WS}}^2}{8d}& \left(1\right)\end{array}$

Here, W is a weight per unit length [kg] of an installed power line and a communication line, S is a horizontal distance [m] to an adjacent utility pole, and d is the slackness [m] of the cable.

An unbalanced load applied to the utility pole by the power line and the communication line increases during a wind, compared with the unbalanced load during no wind. A load generated in the power line and the communication line due to a wind is expressed by the following Expression (2).

$\left[\mathrm{Math}.2\right]$ $\begin{array}{cc}{W}_c=K·\sum D·S& \left(2\right)\end{array}$

Here, W_c (N) indicates a load generated in the cable, K (N/m²) represents a coefficient depending on a type of wind pressure load, ED (m) represents a sum of outer diameters of cables, and S (m) represents a distance between utility poles. The sum of the outer diameters means a diameter including all the electric wires when the cable includes a plurality of electric wires.

A weight W₁ (N/m) of a cable per unit length in consideration of a wind pressure load is expressed by the following Expression (3).

$\left[\mathrm{Math}.3\right]$ $\begin{array}{cc}{W}_1=\sqrt{W_0^2+W_c^2}& \left(3\right)\end{array}$

When Expression (3) is substituted into W in Expression (1), un unbalanced load T applied to a utility pole when a cable is laid is obtained.

$\left[\mathrm{Math}.4\right]$ $\begin{array}{cc}T=\frac{W_1{S}^2}{8d}& \left(4\right)\end{array}$

As described above, the unbalanced load T applied to the utility pole is calculated by converting an influence of the wind.

Next, Procedure 2 will be described.

FIG. 5 is a diagram illustrating a force generated in the utility pole 10 on which the jig 30 is installed. At this time, the force exerted on the utility pole 10 by the cable 11 laid on the utility pole 10 is an unbalanced load F. The height of the attachment position of the jig 30 from the ground 50 is h [m], the height of the attachment position of the upper branch wire 15-1 with respect to the utility pole 10 from the ground 50 is H [m], an attachment angle of the upper branch wire 15-1 is θ [°], and a length of the jig 30 is a [m].

At this time, on the assumption that the upper branch wire 15-1 is stretched by a tension of F [kN], a load amount P [kN] that can be shared by the upper branch wire 15-1 can be expressed in the following Expression (5).

$\left[\mathrm{Math}.5\right]$ $\begin{array}{cc}P=F\sin \theta & \left(5\right)\end{array}$

A relationship between the angle θ and the length a is expressed in the following Expression (6).

$\left[\mathrm{Math}.6\right]$ $\begin{array}{cc}a=\left(H-h\right)\tan \theta & \left(6\right)\end{array}$

For example, when the jig 30 is attached at a position of H=6 m and h=3 m and a branch wire tension is reached at F=10 kN, the relationship between the length a [m] of the jig 30 and the load amount P [kN] secured by the branch wire is as illustrated in FIG. 6.

FIG. 6 is a graph illustrating the relationship between a and P when the length a of the jig 30 is represented by the horizontal axis and the load amount P that can be shared by the upper branch wire 15-1 is represented by the vertical axis when the branch wire angle θ is changed from 0° to 60°. As illustrated in the graph, only when the length of the jig 30 is changed by about a=0.1 m, a difference in the load amount P that can be secured by the upper branch wire 15-1 is 0.1 to 0.35 kN.

Next, Procedure 3 will be described.

The load amount of the utility pole depends on a type of utility pole and is about 2 kN at the minimum. As in the relationship of FIG. 6, a difference occurs in the load amount in accordance with the length a of the jig 30. Therefore, an unbalanced load of around 10% remains unless the length a of the jig 30 is adjusted. Accordingly, based on the relationship of FIG. 6, the length a of the jig 30 that generates the load amount P cancelling the unbalanced load T calculated in Procedure 1 is found.

Finally, Procedure 4 is performed. The expansible mechanism 34 of the jig 30 is adjusted so that the length a found in Procedure 3 is obtained.

As described above, it is necessary for the expansible mechanism 34 to be able to adjust the length a of the jig 30 in the order of 10 cm to eliminate an unbalanced load of around 10%. In this way, in order to appropriately eliminate the unbalanced load T generated on the utility pole 10, it is necessary for the jig 30 to have a function of adjusting the length a flexibly.

REFERENCE SIGNS LIST

• • 10 Utility pole
  • 10 a Top portion
  • 15 Branch wire
  • 15-1 Upper branch wire
  • 15-2 Lower branch wire
  • 16 Anchor
  • 20 House
  • 30 Jig
  • 30 a One end
  • 30 b Other end
  • 31 First member
  • 32 Second member
  • 33 Band
  • 34 Expansible mechanism
  • 50 Ground surface

Claims

1. A jig of which one end is configured to be attached to a surface of a utility pole to be perpendicular to the utility pole, the jig comprising: a first member configured to hold an upper branch wire connected to a top portion of the utility pole at another end; anda second member configured to hold a lower branch wire connected to a ground in parallel with the utility pole.

2. The jig according to claim 1, further comprising an expansible mechanism that makes a length in a longitudinal direction variable.

3. A laying method comprising: attaching one end of a rodlike jig to a surface of a utility pole to be perpendicular to the utility pole;connecting another end of the rodlike jig to a top portion of the utility pole by an upper branch wire; andconnecting the other end of the rodlike jig to a ground by a lower branch wire so that the lower branch wire is parallel to the utility pole.

4. The laying method according to claim 3, further comprising: calculating an unbalanced load applied to the utility pole;acquiring a relationship between a length of the rodlike jig in a longitudinal direction and a load amount generated in the upper branch wire;finding the length of the rodlike jig for eliminating the unbalanced load from the relationship; andsetting the length of the rodlike jig attached to the utility pole to the length found from the relationship.