JP3518877B2 - Power cable laying method at the bridge end - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for laying a power cable laid on a bridge at an end of the bridge, and more particularly to a bending for expansion and contraction between the bridge end and the ground. The present invention relates to a laying method in a case where there is no sufficient head to form an arc. 2. Description of the Related Art In addition to thermal expansion and contraction of a power cable laid on a bridge, expansion and contraction of a bridge girder and a change in angle (a corner break) occurring at an end of the bridge are required. ) Is added. FIG. 3 is an explanatory view of an example of a conventional method of laying a power cable at an end of a bridge to absorb such expansion and contraction. As shown in the drawing, a power cable 1 attached to a bridge is fixed with a cleat 3 or the like at a bridge girder 2 bridge, laid in a right angle bend 11 with a ground fixed point 12, and the expansion and contraction M at a bridge end is bent as described above. Changes in the bending radius of the arc part 11
It is absorbed by 11 '. However, this method requires a sufficient head H for forming a bent shape between the bridge end and the ground surface, and has a problem that it cannot be applied when the head H is small. FIG. 4 is an explanatory view of another example of a conventional method of laying a power cable at an end of a bridge. As shown in the drawing, the power cable 1 is fixed on the end girders 2 with the cleats 3 and fixed with the fixing anchors 4 provided on the ground side. Then, a cable offset portion 5 for absorbing expansion and contraction M at the end of the bridge is provided on the bridge girder 2, and a corner break absorbing device 13 (details omitted) is provided. Thus, the expansion / contraction M at the bridge end is absorbed by the deformation 5 ′ of the cable offset portion 5, and the corner break generated at the bridge end is absorbed by the corner break absorber 13. However, this method places a heavy load on the bridge because a device to absorb expansion and contraction and a device for absorbing corner breaks are installed on the bridge, and a fixed anchor is installed on the ground to reduce the amount of expansion and contraction at the bridge end. There was a need to ensure that it would join the power cable. SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and makes it possible to absorb expansion and contraction even when there is not a sufficient drop between the bridge end and the ground surface, and to reduce the length of the bridge. intended to provide a laying method of a power cable at the bridge end to reduce the weight burden, its features, in order to form a bending arc for stretching absorption between the bridge end and the ground surface was添架laying power cables This is a method of laying power cables at the bridge end when there is no head drop, where the cable is fixed to the bridge girder at the bridge end, and then the expansion and contraction amount of the cable is directly added to the cable offset section. Through the ground, between the transition frame and the ground-side fixed anchor
It is another object of the present invention to form a convexly bent cable offset portion for absorbing expansion and contraction of a bridge end in a part of a cable laid in a straight line . FIG. 1 is an explanatory view of a concrete example of a laying method according to the present invention. As shown in the drawing, a power cable 1 laid along a bridge is fixed to a bridge girder 2 by cleats 3 at a bridge end, and a head H between a bridge girder 2 provided at a lower portion of the bridge girder 2 and the ground surface is eliminated. The cable 1 is guided to the ground through a transition frame 6 for smoothly transitioning the cable. Then, after forming a cable offset portion 5 for absorbing the expansion and contraction M of the bridge end on the ground, the cable 1 is fixed to the ground by the fixing anchor 4. By such laying, the expansion and contraction M generated at the bridge end is applied to the cable in parallel with the ground surface, and is absorbed by the deformation 5 ′ of the cable offset portion 5. FIG. 2 is an explanatory view of another embodiment of the laying method of the present invention. In the case where only expansion and contraction occurs at the bridge end, the specific example shown in FIG. 1 may be used, but corner breakage may also occur. In this case, a corner break absorbing device is provided between the ground transition point A of the cable 1 and the cable offset portion 5. The angle-break absorbing device includes an intermediate frame 7 and pins 8a and 8b for changing the angle on both sides of the intermediate frame 7. A moving roller 10 and the like are provided between the frame member 9 on the cable offset section 5 side and the ground.
Is made to expand and contract in parallel with the ground surface. Since the angle breaks occurring at the bridge end also occur in the horizontal direction in addition to the vertical angle breaks, the angle changing pins 8a and 8b have a structure that can change the angle in the horizontal direction as well as in the vertical direction. . [0007] As described above, according to the laying method of the present invention, the power cable attached to the bridge is guided to the ground through the transition frame, and the expansion and contraction of the cable is performed in parallel with the ground surface. Therefore, even if there is no sufficient drop between the bridge end and the ground, expansion and contraction can be reliably absorbed by the cable offset portion. In addition, since the absorbing device such as expansion and contraction and corner bending is installed on the ground after descending the bridge end, the installation space on the bridge girder is reduced, and the weight burden is also reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a specific example of a laying method of the present invention. FIG. 2 is an explanatory diagram of another specific example of the laying method of the present invention. FIG. 3 is an explanatory diagram of an example of a conventional laying method. FIG. 4 is an explanatory view of another example of a conventional laying method. [Description of Signs] 1 Power cable 2 Bridge girder 3 Cleat 4 Ground-side fixed anchor 5 Cable offset part 6 Transition frame

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Naohide Urakawa               Kansai, 3-2-2 Nakanoshima, Kita-ku, Osaka-shi               Inside Electric Power Company                (56) References JP-A-3-289317 (JP, A)                 JP-A-3-289316 (JP, A)                 JP-A-3-169215 (JP, A)                 Actual opening 1983-25516 (JP, U)                 "For a 77kVCV cable with a long bridge added               For long and large offsets               Development of Actuating Mechanism '' 1988 National Institute of Electrical Engineers of Japan               Proceedings, Vol. 1988, No.               11, p1677-1678 (1988.03.10)

Claims (1)

(57) [Claims 1] A bridge end in the case where there is no drop to form a curved arc for absorbing and contracting the expansion and contraction between the bridge end on which the power cable is laid and the ground surface. The power cable laying method according to the above, wherein the bridge end extends from the bridge end to the vicinity of the ground surface in order to directly add the cable expansion / contraction amount to the cable offset portion.
Advance comprises a migration frame that, after fixing the cable to the bridge girder at the bridge end is guided on the earth cable through the <br/> in the migration for frame, the migration frame and the ground-side fixing anchor A cable offset portion bent in a convex shape for absorbing expansion and contraction of a bridge end at a part of a cable laid in a straight line between the power cable and the power cable at the bridge end. .