JPH01275984A - Method for replacing existing main pipe with new one and device thereof - Google Patents

Abstract

PURPOSE:To make an old pipe easily replaceable with a new pipe by attaching the new pipe to the rear end of a drilling machine and, when a tip of this drilling machine is inserted into the old pipe, quickly cooling the old pipe from the inner circumferential side before it is broken. CONSTITUTION:A new pipe 6 is attached to the rear end of a drilling machine 2 with a barrel in outer diameter larger in outer diameter than that of an old pipe 1 buried in the ground. A tip of the drilling machine 2 is inserted into the old pipe 1 via a cable 3 attached to the front of this drilling machine 2, thereby opening a void wide as breaking the old pipe 1, and it is replaced with the new pipe 6. At this time, the old pipe 1 is quickly cooled by a refrigerant 8 of liquid nitrogen or the like in a refrigerating vessel 7 from the inside before it is broken. In consequence, the old pipe can be easily broken, so that the old pipe is replaceable with the new one without entailing any hindrance to surrounding traffic.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a method for replacing old pipes buried underground, such as water pipes and gas pipes, with new pipes, and in particular, a method for replacing old and new pipes without digging up the ground surface. It concerns how to replace it.

[Conventional technology] When old pipes, especially cast iron pipes, become aged after being buried and become difficult to perform their functions, or when demand increases and capacity is insufficient to replace them with new pipes, it is necessary to excavate the entire surface above ground. Digging out old pipes is expensive and labor-intensive, and it also obstructs surface traffic, so it is preferable to replace the old and new pipes without digging up the ground.

This is the case with the so-called pipe-in-pipe method, in which a new pipe is inserted into an old pipe underground, but the inner diameter of the new pipe is naturally smaller than the inner diameter of the old pipe, resulting in a reduction in gas and water transport capacity.

The prior art that forms the basis of the present invention is an invention that solves this problem: ``Method and apparatus for replacing existing main pipe with new main pipe.''
(Japanese Patent Publication No. 60-27873 No. 2 to Fig. 3) discloses this in detail.

In this conventional technology, the new pipe is attached to the rear end of the excavator, which has a body with a larger outer diameter than the old pipe, and both move forward together, and the tip of the excavator enters the old pipe, crushing it and filling the void. This is a method and device for expanding and replacing old pipes with new ones.

The contents will be explained in more detail based on the embodiment of this prior art shown in FIGS. 2 and 3.

The excavator 2a consists of a front part that enters the inner wall of the old pipe 1a and breaks this wall, and a tangential part that is fastened to pull the new pipe 6a.

The front part has a head including a cutting edge 9 as a cutting surface, and its front end is connected to a winch 4a via a cable 3a that has been inserted through the tube row of the old pipe.

Based on Figure 2, this work procedure is divided as follows.

(1) Attach the new pipe 6a to the rear end of the excavator 2a, and connect a wire or the like between the rear end of the excavator and the tip of the installed new pipe to integrate the excavator and the new pipe.

At this time, an air hose, a hydraulic hose, etc. for driving the excavator are inserted into the new pipe, and the cable 3a of the winch 4a is connected to the front end of the excavator.

(II) Move the excavator along with the new pipe with the tip of the excavator first,
The old pipe 1a was removed by the excavator using an air hammer installed inside the excavator.
The old pipe is broken by hitting the ends, and the new pipe 6a is inserted into the gap in the broken main pipe and laid.

(I) If a liner is used, insert the fr tube into the liner after the liner is in place. (Normally, a liner is often used.) [Problem to be solved by the invention] Since the old pipe is struck by an air hammer and ruptured, the old pipe has high ductility and excellent impact resistance. It is not easy to break these pipes when they are made of pipes (eg, steel pipes, ductile cast iron pipes, etc.). Therefore, the conventional technology cannot be applied to old pipes made of these materials, and even in areas with frequent traffic in urban areas, if it becomes necessary to replace these old pipes, it will cause problems with surrounding traffic. Replacement work must be carried out using the cut-and-cover method, which causes problems.

In addition, even if the old pipe is made of a material with low impact resistance (for example, ordinary VI iron pipe), by the time it becomes necessary to replace the pipe body, it has already been partially repaired several times. In addition, most of the partial repairs are made with steel pipes, ductile iron pipes, or parts made of these materials, so the pipe body is not impact resistant. It is rare for pipes to be formed with low-quality pipes, which often poses an obstacle to adopting this construction method.

Furthermore, by increasing the impact force of the air hammer, it becomes possible to crush the old pipe, which is highly tough, but if the impact is only enough to break the pipe into large pieces, as shown in Figure 4B, excavation is carried out in step 2a. The pipe pieces 5a of the old pipe 1a are abnormally distributed with respect to the outer diameter, and apply uneven pressing force to the surrounding ground. Figure A shows desirable states arranged for comparison.

When the situation as shown in Figure B occurs, it becomes difficult to avoid the following failures as the construction progresses.

(I) Since the resistance received from the surrounding ground increases, the construction efficiency (construction speed, possible construction length) decreases.

(If> Because the ground will be consolidated more than necessary, there is a risk of the road surface being upheaved and adjacent pipes being moved or bent.

(1) The old pipe piece is being pushed towards the excavator and the new pipe by earth pressure. If the old pipe is broken into larger pieces, there are fewer contact points between the old pipe and the excavator and the new pipe, and the edges of the old pipe come into contact at an acute angle, so the excavator and the new Severe wear and damage to pipes.

(IV) Since a gap is formed between the new pipe and the old pipe piece, if the old pipe piece breaks due to corrosion etc. in the future, it will have a large impact on the surrounding ground and cause problems such as road surface collapse. I'm afraid. Furthermore, there is a high possibility that groundwater will pass through these voids, and there is a risk that the new pipes will be worn out by ground runoff and quicksand.

In order to solve the above-mentioned problems, the present invention provides a method and installation for replacing an old pipe with a new pipe, which can be easily applied to old pipes made of highly tough materials such as steel pipes and ductile cast iron. With the goal.

[Means for Solving the Problems] The method of replacing an old pipe with a new pipe according to the present invention solves the above problems by rapidly cooling the old pipe from its inner peripheral side immediately before it is crushed.

In addition, as a device used only for implementing this method, a new pipe is attached to the rear end of the excavator, which has a body with a larger outer diameter than the old pipe buried underground, and a front traction device is attached to the tip of the excavator. A refrigerant container is interposed between the excavator and the traction means to connect a cable connected to the excavator and the traction means, and to squirt a refrigerant into the inner periphery of each pipe while making a turn in the former pipe together ahead of the excavator. do.

[Operation/Example] FIG. 1 does not show an example of the present invention. An excavator 2 with a larger outer diameter enters the end of the old pipe 1 buried underground, and its tip is pulled forward by a winch 4 via a cable 3, crushing the old pipe and cutting it into pieces. It becomes 5. Connected to the rear of the excavator is pipe @6, which replaces the old pipe. A refrigerant container 7 that spouts refrigerant 8 is attached to the front of the excavator 2 and moves forward in synchronization via a cable 3. In this embodiment, a shell-shaped cylinder containing liquid nitrogen is inserted into the old pipe, and the liquid nitrogen is sprayed onto the inner surface of the old pipe from the rear. Ductile cast iron pipes, which are the most common type of water supply pipes, have a high impact resistance value at room temperature, recording 2KgTry/mu2 in the case of Si Half reduction (transition temperature) at L-40℃ is 0.5 K'j m/
Because it falls down to 2 mm2, it not only breaks easily with a mild impact, but also has the characteristic that the tube fragments become as fine as glass or ceramic pieces. In this embodiment, the cylinder is connected just before the excavator and only the crushed portion of the old pipe is locally and rapidly cooled, so the old pipe never becomes a large piece of pipe. Also, for the same reason, the old pipe will not break before the excavator reaches it, so there is no need to worry about the ground sinking.

The same can be said for vinyl chloride pipes (PVC pipes) as for steel pipes and ductile pipes. However, the transition temperature is much higher than that of steel pipes or ductile cast iron pipes, so cooling is easier.

Further, other coolants other than liquid nitrogen may be used as long as they satisfy the above effects. In addition, as long as the cooling device can be inserted into the old pipe, the cooling temperature, cooling area, and cooling depth can be adjusted depending on the material and thickness of the old pipe, and the advancing speed of the excavator, regardless of the type or construction. If you set it up, you will achieve your goal.

The operational feature of this method and device is that instead of cooling the entire old pipe in advance, it is only necessary to cool a small part in front of the excavator for a short period of time before it breaks, so there is no loss in cooling. There is no need for cooling equipment, which is a big deal.

Furthermore, since only a portion of the old pipe is cooled for a short period of time, there is no need for excessive cooling, so freezing of the surrounding ground is limited to only a small portion, and there is no problem with construction.

If the old pipes are cooled in a lattice pattern, the volume of the part to be cooled can be reduced and efficiency is improved. This method also makes it possible to control the size of the fragments.

[Effect of the invention] As stated above, the present invention solves all the problems mentioned in the problem section, greatly expands the applicable range of the prior art, and applies exceptions to all materials that are normally buried underground. produces an effect that can be applied without any restrictions.

Furthermore, since a separate cooling device from the excavator is simply attached to the front of the excavator, it is easy to implement, and the construction procedure is no different from conventional methods.

If liquid nitrogen is used as a refrigerant, it will be easier to obtain, more efficient,
It seems possible to achieve the most satisfactory results in terms of safety and health.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing an embodiment of the present invention, FIGS. 2 and 3 are front sectional views showing a prior art, and FIGS. 4A and 4B are side sectional views showing problems of the prior art.

Claims (2)

[Claims] (1) A liner (hereinafter referred to as the "old pipe") at the rear end of the excavator that has a body with a larger outside diameter than the existing main buried underground or serves as a protective sleeve for the new main. In this method, the old pipe is replaced with the new pipe by installing the new pipe (hereinafter referred to as "new pipe"), moving forward together, and inserting the tip of the excavator into the old pipe, crushing it and expanding the gap. A method of replacing an old pipe with a new one, which is characterized by rapid cooling from the inner circumferential side of the pipe immediately before it is crushed. (2) Attach a new pipe to the rear end of the excavator, which has a body with a larger outer diameter than the old pipe buried underground, and connect the cable to the front traction means to the tip of the excavator. In this device, the tip of the excavator moves forward together and the tip of the excavator enters the inside of the old pipe, crushing it and expanding the gap to replace the old pipe with a new pipe. A device for replacing an old pipe with a new pipe, characterized by having a refrigerant container interposed therein that spouts refrigerant onto the inner periphery of the pipe while moving forward together with the machine.