WO1982003644A1

WO1982003644A1 - Road culvert

Info

Publication number: WO1982003644A1
Application number: PCT/FI1982/000013
Authority: WO
Inventors: Matti Mertsalmi
Original assignee: Matti Mertsalmi
Priority date: 1981-04-15
Filing date: 1982-04-14
Publication date: 1982-10-28
Also published as: FI811183L; NO824182L

Abstract

Road culvert comprising at least two plastic pipes (1). In order to prevent lateral flow along the outer surface of the pipes ad for fastening the pipes to each other transverse closure plates (2, 3) surround the pipes, said plates being located near the pipe ends.

Description

Road culvert

The present invention relates to a road culvert comprising at least two plastic pipes to be positioned transversally of the road.

Road culvert pipes made of plastic are lightweight and do not exert stresses even on a soft installation ground. They require no particular foundation nor any insulating or protective layer but the excavation can be filled with excavated earth. One more advantage associat¬ ed with plastic pipes is that debris do not stick to the smooth inner surface.

In connection with floods it sometimes happens that- water penetrates into the ground surrounding the culvert in such quantities that a lateral flow arises along the outer surface of the pipe. Such a lateral flow entrains earth from the side of the pipe. Now it has been noted that lightweight plastic pipes having a smooth outer sur¬ face may easily be longitudinally displaced along with the lateral flow because the frictional holding force of the earth layers is reduced. This displacement may result in the destruction of the entire culvert. Because the lateral flow mainly carries away li^'ght soil material while stones remain in place, the foundation of the pipe will become uneven. Peak loads are then exerted on the pipe as a result of which the plastic pipe may collapse.

Lateral flows can be omitted and the pipe anchored in the ground by providing the pipe with a transverse closure plate, see, for example, U.S. Patent Specification 2 439 488. The closure plate prevents lateral flows along the outer surface of the pipe and thus also the displace¬ ment of the pipe in its longitudinal direction and flatte¬ ning thereof due to peak loads. Also in the event that lateral flows for some reason arise, the closure plates keep the pipe in place because they penetrate into the surrounding ground. In order to limit the construction height, the road culvert is often made of two or more adjacent pipes instead of one large-diameter pipe. The pipes can be loose but most often they are fastened to each other by means of fastening means.

The object of the present invention is to provide a road culvert comprising at least two pipes in which lateral flows are prevented and the pipes are fastened to each other in a very simple manner. The invention is characterized in that the pipes are surrounded by at least one common closure plate perpendicular to the centre line of the pipes. By providing the pipes with common closure_ plates lateral flows are prevented and, at the same time, the pipes will be fastened to each other. Thus, the closure plate having openings for at least two pipes serves two purposes, i.e. to prevent lateral flows and to join the pipes to each other.

In the following, the invention will be described in more detail with reference to the accompanying drawing, in which

Figure 1 shows a road culvert comprising three pipes in which the pipes are positioned side by side, and

Figure 2 shows a road culvert comprising three pipes in which the pipes form a triangle. Often it is advisable to assemble a road culvert from a plurality of pipes in which case closure plates can be used for fastening the pipes to each other to form a culvert element. Figure 1 shows a culvert element com¬ prising three adjacent pipes 1 joined to each other in pairs by means of closure plates 4, 5, 6 and 7. In this case, the closure plates are rectangular and provided with two holes for a pair of pipes. Because both closure plates at the same end are pushed on the middlemost pipe, all three pipes can be joined to form one culvert element. Said three pipes can be positioned to form a triangle by turning one of the lateral pipes on top of the two other pipes and by fastening it to the other lateral pipe by means of the closure plates.

According to the Figure, the closure plates 4, 5, 6 and 7 are mounted close to each end of the pipes. Accor- 5 ding to the situation, the closure plates can also be located at any desired location along the length of the pipe. In general, the best effect is obtained if they are located at some distance from the pipe ends or at the ends. As regards the function of the closure plates, it is 10 moreover essential that their lateral surfaces are large enough. The suitable area mainly depends on the soil. When the closure plate has been pushed on the pipes, it can be either welded to the outer surface of the pipes or be left loose in which case it remains in place by 15 means of friction.

Figure 2 illustrates a triangular road culvert element in which the uppermost pipe serves as overflow pipe for flood waters. In this case the closure plates 8, 9 and 10 are triangular and provided with three holes 20 for the pipes 1. In the middle of the pipes is mounted an additional closure plate 9 which improves the operation of the closure plates. It is also possible to mount a larger number of closure plates along the length of the pipes than as in the embodiment described above. The 25 number of pipes in the road culvert element can also be later increased in the desired manner by connecting pipes to each other by means of closure plates.

Preferably, the closure plates are made of the same

St- plastic material as the pipes in which case they can be 30 hot-air welded to the pipes. Instead of the connection shown in Figure 1 , adjacent pipes can be connected to each other by means of closure plates extending along the entire row of pipes. In some cases it may be advisable to use only one closure plate located, for example, centrally

Claims

Claims :

1. A road culvert comprising at least two inter¬ connected plastic pipes (1) to be positioned transversal- ly of the road, c h a r a c t e r i z e d in that the pipes (1) are surrounded by at least one common closure plate (4-10) perpendicular to the centre line of said pipes.

2. A road culvert according to claim 1 , c h a r- a c t e r i z e d in that a third pipe is connected to a pair of pipes having common closure plates by means of providing said third pipe with closure plates (6,7) surrounding also one of the pipes in said pair of pipes.

3. A road culvert according to claim 1 or 2, c h a r a c t e r i z e d in that the closure plates

(4-10) are fastened to the pipes (1) by means of frictional force or welding.