JP3647242B2 - Pipe-in-pipe construction method for curved pipes - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pipe-in-pipe method for a bent pipe portion.
[0002]
[Prior art]
A pipe-in-pipe method is known as a method for renewing existing pipes.
This pipe-in-pipe method is to push a new pipe with a small diameter around the existing pipe from the opening of one end of the existing pipe and push it in the direction of the pipe axis. Compared with the excavation method that replaces with, it has the advantage of being very economical.
[0003]
In addition, since it is possible to renew a long pipe just by providing a start shaft, it has the advantage that it is very advantageous as a pipe renewal method in urban areas where it is difficult to implement the excavation method due to traffic conditions and underground buried objects. .
[0004]
However, since the pipe-in-pipe method pushes new pipes sequentially into existing pipes, there is a problem that if the pipe 1 has a bent portion 2 as shown in FIG. It was.
[0005]
That is, since the straight pipe 3 that has been traveling straight hits the inner wall of the bent portion 2 and is bent greatly at that portion, the bending angle α of the joint portion 3A of the straight pipe 3 is increased, and the allowable bending at the joint portion is increased. When the folding angle is small, it is not applicable as shown in the figure.
[0006]
For this reason, conventionally, when there is a bent portion in the pipeline, a vertical shaft is provided at the start and end points of the bent portion, and a bent pipe piece is constructed from this vertical shaft to the bent portion, and then a straight pipe is inserted from both sides. A method of connecting to the bent pipe piece at a shaft portion, a short straight pipe that can pass through a bent portion of an existing pipe line, are carried into the existing pipe one by one and connected in the pipe.
[0007]
[Problems to be solved by the invention]
However, the former method of constructing new shafts at both ends of the pipe bend may not be implemented due to road conditions or underground construction, and the latter method of carrying short tubes is used for transporting pipes. When it is very time-consuming and is pulled with a wire, etc., the tube is pulled in, it is troublesome to install and manage the wire support means on the way, and when the wire is stretched, the wire jumps when traction force is applied suddenly In some cases, pulsation may occur, the inner wall of a new pipe or existing pipe may be struck hard and damaged, and it may be very dangerous.
[0008]
The present invention has been made for the purpose of solving the above-mentioned problems, and has been made for the purpose of enabling the pipe-in-pipe method even if the pipe has a bent portion.
[0009]
[Means for Solving the Problems]
That is, the pipe-in-pipe method of the bent pipe portion according to the present invention has a gradual radius larger than the radius of the existing pipe bent portion where the straight pipe connected to both ends of the bent portion is tangent to the outermost peripheral portion of the inner surface of the existing pipe bent portion. A curved surface is formed, and the straight pipe inserted in the tube is sequentially fed from the straight pipe portion toward the curved surface.
[0010]
A curved surface with a radius larger than that of the bent portion is formed on the outer surface of the bent portion so that the straight pipe is tangent, so that the direction of the newly inserted tube that has been propelled through the existing straight pipe can be smoothly changed by the curved surface. Since the radius is increased, the bending angle applied to the joint portion of the new pipe is also reduced.
[0011]
Therefore, it is possible to carry out a pipe-in-pipe method in which straight pipes are joined as they are even if there is a bent portion of the pipe line.
The pipe-in-pipe method for the bent pipe part according to claim 2 is the pipe-in-pipe method for the bent pipe part according to claim 1, wherein the pipe-in-pipe method is formed on the innermost inner peripheral part of the existing pipe bent part at the innermost outer peripheral part of the existing pipe bent part. A curved surface that is substantially parallel to the curved surface and shares the vertex of the innermost inner peripheral portion of the bent portion is formed.
[0012]
Since the innermost peripheral surface corresponding to the curved surface of the outermost curved surface of the bent portion is provided substantially parallel to the outer peripheral curved surface, the new insertion tube that has been propelled is guided in the direction of the outer curved surface by the curved inner surface, and locally Since the bending is prevented, the tube can be pushed more smoothly.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described.
FIG. 1 is a cross-sectional view showing an implementation state of a pipe-in-pipe method for a bent pipe part according to claim 1.
[0014]
In FIG. 1, reference numeral 1 denotes an existing pipe having a bent portion 2.
A gentle curved surface 5 having a radius R larger than the radius r of the existing tube bent portion 2 is formed on the outermost inner surface 2A of the bent portion 2 with the straight pipes 4 and 4 connected to both ends of the bent portion 2 as tangents. Then, as shown in the figure, the in-tube insertion straight pipes 3... 3 are fed toward the curved surface 5 while being sequentially joined.
[0015]
Accordingly, the bending angle θ of the in-tube insertion straight pipes 3... 3 is smaller than the bending angle α of the bent portion 2 of the existing pipe 1, so that even the long straight pipe 3 can be easily passed through the bent portion 2.
In the above, since the curved surface 5 only needs to be guided by contact with the outermost peripheral portion of the insertion straight pipe 3, it is only necessary to bend and install a member such as a wooden or FRP bar having a small surface friction. It is enough. Note that the curved surface 5 may be formed by placing concrete as indicated by the dotted diagonal lines.
[0016]
FIG. 2 is a cross-sectional view showing an implementation state of the pipe-in-pipe method for the bent pipe part of claim 2.
In this case, in the above pipe-in-pipe method, the bent portion 2 is substantially parallel to the curved surface 5 formed in the innermost outermost peripheral portion 2A of the existing pipe bent portion 2 on the innermost inner peripheral portion 2B of the existing pipe bent portion 2. A curved surface 6 sharing the vertex 2P of the innermost innermost peripheral portion of the inner surface is formed.
[0017]
Then, as shown in FIG. 2, the straight pipe 3 is inserted toward the bent portion 2.
Since the curved surface 6 only needs to be guided by contact with the innermost peripheral portion of the insertion straight pipe 3 in the same manner as the curved surface 5, the curved surface 6 bends a member such as a wood having a small surface friction or a FRP bar. It is enough to install it.
[0018]
Needless to say, the curved surfaces 5 and 6 may be formed by placing concrete as indicated by the dotted diagonal lines.
When configured as described above, even when the insertion straight pipe 3 advances along the inner surface side of the existing pipe 1 as shown at the right end of FIG. Since the direction is smoothly changed in the direction of the surface 5, the tube can be surely propelled.
[0019]
Therefore, it is preferably used when the difference between the inner diameter of the existing pipe 1 and the outer diameter of the new pipe 3 is large and the position of the new pipe fluctuates within the existing pipe.
[0020]
【The invention's effect】
As described above, according to the invention of claim 1, when the new straight pipe is inserted into the existing pipe while being sequentially joined, the refraction angle of each new straight pipe at the bent portion is considerably reduced. Even straight pipes that are somewhat long can be applied to the pipe-in-pipe method, and it is possible to easily lay bent pipes without using special means.
[0021]
According to the invention of claim 2, the insertion straight pipe is guided by the inner side curved surface and the outer side curved surface, so that the insertion straight pipe is reliably guided, and there is a large diameter difference between the existing pipe and the new pipe. But it has the effect of being able to work safely.
[Brief description of the drawings]
1 is an explanatory sectional view showing an embodiment of the invention of claim 1;
FIG. 2 is an explanatory sectional view showing an embodiment of the invention of claim 2;
FIG. 3 is an explanatory sectional view of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Existing pipe 2 Bending part 2A Outermost-periphery inner surface 2P of a bending part The vertex 3 of the innermost inner peripheral part of a bending part 3 In-tube straight pipe 4 Straight pipe 5 connected to both ends of a bending part 5 Curved surface 6 Curved surface r Radius R Radius of curved surface θ Bending angle of straight pipe inserted in pipe α Bending angle of existing pipe bending part

Claims (2)

A gradual curved surface having a radius larger than the radius of the existing pipe bending portion, which is tangent to the straight pipe connected to both ends of the bending portion, is formed on the outermost inner peripheral portion of the inner surface of the existing pipe bending portion. Pipe-in-pipe construction method for curved pipes, which feeds straight pipes inserted into the pipes while being sequentially joined. 2. The pipe-in-pipe method for a bent pipe part according to claim 1, wherein an innermost inner surface of the bent part is substantially parallel to a curved surface formed on an innermost outermost part of the existing pipe bent part at an innermost inner peripheral part of the existing pipe bent part. A pipe-in-pipe construction method for a curved pipe part, characterized in that a curved surface sharing the vertex of the peripheral part is formed.

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