JPS5855729B2 - How to prevent gearoping in self-supporting cables - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing gear roping of a self-supporting cable (a phenomenon in which when a non-circular cable receives wind from the side, a lifting force is exerted and the cable vibrates like a jump rope).

When a self-supporting cable 1 such as the self-supporting leaky coaxial cable shown in FIG. 1A receives wind from the side, the cable main body 1B is larger than the messenger wire portion 1A as shown in FIG. 1B. The disadvantage is that the self-supporting cable is easily cut off by the support part, such as a utility pole, when it is blown away and receives lift, causing jump-rope-like vibrations with the support parts such as telephone poles as nodes of vibration and the center between the support parts as the antinode of vibration. was there.

At present, no proper method has been established to prevent such gearropping.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for preventing gear lopping of a self-supporting cable, which can easily prevent gear lopping.

An example of the method of the present invention will be described in detail below with reference to FIGS. 2 to 9.

The present inventors stretched the self-supporting cable 1 between the supports 2 and 2' as shown in FIG. Clamp the sender wire 3 to the sender wire part 1A of the self-supporting cable with a clamping tool 4 at appropriate intervals in the length direction, and set the distance of the second messenger wire 3 for one person to the sender wire part. When wind cylinder experiments were conducted with various changes and the locus of the center of the span of the self-supporting cable 1 was measured, the results shown in FIG. 3 were obtained.

In the figure, O is the position of the self-supporting cable when there is no wind, and A is the position of the self-supporting cable when only the self-supporting cable 1 is stretched as shown in Figure 4A. 1, the locus B is a double messenger wire type in which the second messenger wire 3 is stretched over the self-supporting cable 1 and both are clamped with a clamping tool 4, as shown in FIG. 4B. In addition, the trajectory of the cable 1 when the relationship between the distance 1 between the second messenger wire 3 and a part of the messenger wire and the diameter of the cable main body 1B is 2D, C is the same double messenger wire as B. The locus of the self-supporting cable 1 when the distance between l and D is l≧2D in a single cable cable type is shown.

In addition, each condition in this experiment was as follows.

Span length: 8m Self-supporting cable: Messenger wire part 1 person's diameter 5J Messenger wire part The Messenger wire in 1A is a 1.2 #φ pier wire, the length of the neck 1C is 1.
5M, the width of the neck 1C is 1.0M, the diameter of the cable main body 1B is 20W1, the thickness of the plastic coating is 1.0M.Second Mesenger wire: Same clamp tool spacing as part of the Messenger wire of self-supporting cable: 1 .5 m Wind for laying cables 13 to 19: 10 m/sec Through the above experiments, it was found that gear roping can be prevented by setting the relationship between l and D to be l≧2D.

This is because the second messenger wire 3 (a) prevents the self-supporting cable 1 from tilting and increasing lift when it receives crosswinds, and (b) suppresses the natural vibration of the self-supporting cable 1. This is to create a damper effect that causes disturbance.

In particular, both effects (a) and (b) indicate that the second messenger wire 3 does not appear unless it is a certain distance away from the self-supporting cable 1 (i.e., l≧2D). .

As explained above, according to the present invention, the second messenger wire is stretched over the self-supporting cable, and the second
The distance l between the messenger wire and a part of the messenger wire of the self-supporting cable was set to l≧2D with respect to the diameter of the cable body, and the two were clamped at appropriate intervals in the length direction with a clamping tool. , (/1') to prevent the self-supporting cable from tilting and increasing lift force;
(b) The damper action that disturbs the natural vibration of the self-supporting cable can be effectively exerted, and especially in the method of the present invention, if the second messenger wire is stretched and clamped to the self-supporting cable. Therefore, it is very easy to implement, and the cost does not increase much, so it is very advantageous in practice.

[Brief explanation of the drawing]

Figure 1A is a cross-sectional view of a self-supporting cable, Figure 1B is an illustration of the cause of gearropping in a self-supporting cable,
Figure 2 is an explanatory diagram of the gearropping prevention experiment, Figure 3 is a locus diagram of the points formed by the self-supporting cable showing the results of the wind cylinder experiment, and Figure 4 A, B, 0 are explanatory diagrams showing each state of the experiment. It is. 1...Metssenja wire 1A...
・Metsuse 1 Njawire part, 1B...Kefle body, 2゜2'...Strut, 3...
2nd measuring wire 4... Clamping tool.

Claims (1)

[Claims] 1. A second messenger wire is stretched over the stretched self-supporting cable, and the distance l between the second messenger wire and a portion of the messenger wire of the self-supporting cable is adjusted to the self-supporting cable. l≧D with respect to the diameter of the cable main body of the type cable, and the part of the second messenger wire is clamped to the part of the messenger wire by a clamping tool at an appropriate interval in the length direction. A method for preventing gearropping in self-supporting cables.