JPH0432196B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a construction method for replacing underground pipes, and more specifically, the present invention relates to a construction method for replacing underground pipes, and more specifically, for replacing underground pipes, etc. with new pipes without digging up the topsoil of the buried location. This article relates to a method for replacing buried pipes that can be replaced.

[Conventional technology]

In recent years, many pipes for domestic water, gas, and electricity have been laid underground, and road construction is also progressing rapidly. Such roads often have sewer pipes and the like buried along them. Many of the old buried pipes are ceramic pipes, and after long-term use they may deteriorate or need to be replaced with larger diameter pipes. In such cases, it would be desirable to be able to bury new pipes so as not to impede traffic such as cars.

For this reason, a replacement method that avoids digging up the road has been used for some time. As an example, as stated in Japanese Patent Publication No. 60-27873,
A known construction method involves breaking an old pipe, inserting a new pipe in its place, and leaving fragments of the old pipe in the ground around the new pipe.

This construction method will be briefly explained based on FIG. Two pits 12,1 are placed in advance on both sides of the road 13.
5 is formed, the new pipe 10 is lowered, and the new pipe 1
A jack 5 and a towing rod 7 for pulling 0 into the ground are lowered. The size of the pit can be kept to the minimum size necessary to successively add new pipes, traction rods, etc. within the pit.
A traction rod 7 is inserted into the old pipe 3 from the pit 12 on the side reinforced with a concrete wall 14 or the like, and is extended until its tip reaches the pit 15. In the pit 15, a crushing head 34 is attached to the tip of the pulling rod 7 via a wire 18, etc., and the new pipe 10 is then pulled via the retracting rod 17 and a backing plate 27.

The crushing head 3 is activated by operating the jack 5, etc.
4, the old pipe 3 is broken by the conical surface of the crushing head 34, and the new pipe 10 is inserted into the ground. The old pipe 3 becomes a fragment 3a and is left around the new pipe 10. When one new pipe 10 enters the underground 2, the next new pipe 10A is lowered at the pitch 15. The traction rod 7 that came out to the pit 12 is cut, the backing plate 27 is removed from the pit 15, and the new pipe 10A is removed.
The retracting rod 17 that has been inserted in advance is connected, and the new pipe 10A is connected after the preceding new pipe 10B. A caul plate 27 is attached to the rear of the new pipe 10A and secured to the retracting rod 17. On the other hand, in the pit 12, the jack 5 again holds the cut tip of the traction rod 7. When the jack 5 operates, the new pipe 10A is also drawn into the underground 2. When such operations are repeated one after another, the tip of the new pipe 10B reaches the pit 12, and the relining is completed. In addition, in the figure, an impact propulsion device 9 is installed after the crushing head 34, and it not only breaks the old pipe 3 with the traction force of the jack 5, but also uses a blower that moves with the compressed air from the air compressor 16. The rupture of the old pipe 3 is also promoted using the impact force of the pipe 3. Regardless of the breaking method, the new pipe is laid without digging up the topsoil in which the old pipe was buried, and the old pipe is left underground as fragments.

On the other hand, Japanese Unexamined Patent Publication No. 62-25697 describes a replacement method in which an old pipe is pushed out when a new pipe is inserted. In this case as well, the old pipe and new pipe are moved by operating the jack in almost the same procedure as above, the old pipe that has been pushed out is recovered, and the new pipe is buried in the position where the old pipe was. Ru.

[Problem to be solved by the invention]

In the former example mentioned above, if the old pipe is a ceramic pipe, it will not be damaged, but depending on the material of the old pipe, there is a risk that it will be damaged when the new pipe advances, and the fragments are useless. In the latter example mentioned above, the old pipe is removed, so
This avoids damage when inserting a new tube due to remaining debris, but if the old tube is old, it will collapse during extrusion and it will no longer be possible to recover the old tube. . In addition, if the collapsed old pipe remains, it becomes even more difficult to insert a new pipe, and the replacement work itself becomes impossible. Therefore, reinforcement such as filling the old pipe with mortar is required, leading to problems such as prolonging construction work and increasing work costs.

By the way, as shown in Fig. 11, if the old pipe 3 is bent at the connection part 3M due to the action of earth pressure, etc.
There are problems in that a large amount of force is required to pull out the old pipe 3, and the insertion position of the new pipe is undesirable, which impairs smooth burying of the new pipe.

The present invention was made in view of the above-mentioned problems.The purpose of the present invention is to avoid damage to the surrounding area during insertion of a new pipe, and to ensure that even old old pipes can be completely cleaned when new pipes are installed. We provide a method for replacing buried pipes that can be recovered in a short period of time, and also ensures straightness when inserting new pipes, making it easier and faster to replace old and new pipes, and saving materials. It is to be.

[Means to solve the problem]

As shown in Fig. 1, the buried pipe re-laying method of the present invention involves removing an old pipe 3 (see Fig. 2) buried underground 2, and installing a new pipe 10 in the buried position of the old pipe 3.
It is applied to the method of replacing underground piping by inserting a pipe and replacing the old and new pipes. The feature is that the old pipe 3
A sheath pipe 4 having an inner diameter larger than the outer diameter of the sheath pipe 4 is fitted and inserted into the old pipe 3 in the underground 2, and at the time of insertion, the entire old pipe 3 is cut and housed, and the sheath pipe 4 and the sheath pipe 4 are cut. The new pipe 10 is inserted and laid while pushing out the old pipe 3.

In the second invention, as shown in FIGS. 8a to 8f, a sheath pipe 4 having an inner diameter larger than the outer diameter of the old pipe 3 is fitted and inserted into the old pipe 3 in the underground 2, and When inserting the old tube 3, the old tube 3 is cut, and the sheath tube 4 accommodates the cut old tube 3 while all the fragments 3a of the old tube 3 are inserted.
and the soil to be excavated around the old pipe 3 until it has a space with an internal volume that can accommodate it,
While the tip of the sheath tube 4 has not yet cut all the old tubes 3, the uncut old tube 3 is cut while moving the sheath tube 4 forward, and at the same time, the sheath tube 4 and the cut old tube 3 are cut.
The new pipe 10 is inserted and laid while pushing out the soil and the excavated soil.

[Effect]

In the first invention, the sheath pipes 4 having an inner diameter larger than the outer diameter of the old pipe are successively connected and externally fitted and inserted into the old pipe 3 in the underground 2 from one pit. As the insertion progresses, the old pipe 3 in the underground 2 is cut, and the sheath pipe 4 moves forward while accommodating this cut old pipe, and the sheath pipe 4 has reached the other pit when all the old pipes 3 after cutting have reached the other pit. included in.

Next, while pushing out the sheath tube 4 and the cut old tube 3, the new tube 10 is inserted and installed into the space created by the removal of the sheath tube 4. The sheath pipe 4 and the old pipe 3 are recovered in the other pit, and as a result, the old pipe 3 is completely replaced with the new pipe 10 without being left underground 2.

In the second invention, the sheath pipes 4 having an inner diameter larger than the outer diameter of the old pipe 3 are successively connected and externally fitted and inserted into the old pipe 3 in the underground 2 from one pit. As the insertion progresses, the old pipe 3 in the underground 2 is cut,
The sheath pipe 4 advances part way while accommodating the cut old pipe 3 and the soil around it, and is stopped with a space left over that can contain the remaining old pipe 3 and the soil around it.

A new pipe 10 is attached to the rear of the sheath pipe 4 in the pit, and while the sheath pipe 4 is moved forward again, the uncut old pipe 3 is cut and its fragments 3a and surrounding soil are enclosed. At the same time, insert the new pipe 10 while pushing out the sheath pipe 4, the cut old pipe 3, and the excavated soil.
Lay down. The sheath pipe 4 and the old pipe 3, as well as the excavated soil, are collected in the other pit, and as a result, the old pipe 3 is buried in the underground 2.
The pipe 10 is completely replaced with the new pipe 10 without being left behind.

〔Effect of the invention〕

In the first invention, when the sheath pipe is fitted over and inserted into the old underground pipe, the old pipe is cut into fragments, and the fragments and excavated soil are stored in the sheath pipe. Since the sheath pipe is pushed out and no fragments of the old pipe are left in the ground, the new pipe being laid will not be damaged by contact with the fragments of the old pipe. Furthermore, when the sheath pipe is fitted and inserted into the old pipe, even if the old pipe is buried in a crooked position, the old pipe is cut and all pieces become pieces, so the sheath pipe can move straight, and the new The pipes are also laid straight, making the work of replacing old and new pipes much easier.

In the second invention, in addition to the above effects,
The sheath pipe was inserted into the ground until it had enough space to accommodate all the pieces of the old pipe to be cut and the soil to be excavated around the old pipe, so the sheath pipe was inserted into both pits. There is no need to insert the tube into the entire gap, which saves on sheath tubes, and makes the work of replacing old and new tubes even faster, more efficient, and at a lower cost.

〔Example〕

Hereinafter, the present invention will be explained in detail based on examples thereof. FIG. 1 is an overall longitudinal cross-sectional view of a state in which the underground pipe resurfacing method according to the first invention is implemented by a resurfacing device 1. This device 1 pulls in a sheath pipe 4 that is fitted over an old pipe 3 buried underground 2 (see Figure 2), cuts the old pipe 3, and removes old pipes that have become fragments 3a together with the sheath pipe 4. A traction means 6 consisting of a pipe 3 and two hydraulic jacks 5, 5 for pushing out the excavated soil, a pressing head 8 connected to the traction means 6 via a traction rod 7, and the pressing head 8. Impact type propulsion machine 9 integrated into
and a retracting means 11 for attaching the new pipe 10 to the pressing head 8.

The above-mentioned jack 5 is installed in a pit 12 on the side where old pipes such as ceramic pipes are pushed out, and is made of concrete that reinforces the soil surface around the tip of the old pipe buried underground 2 across the road 13. Recover the sheath pipe 4 and the cut old pipe while taking the reaction force with the wall 14, etc.
Moreover, it generates a force to push the new pipe 10 into the position where the old pipe was located. In addition, this pit 12
At this point, the extracted sheath tube 4 is cut, so the pit 12 has the minimum length necessary for that purpose.

Sheath pipes such as steel pipes 4 and new pipes such as Huum pipes 10
The pit 15 on the side into which the sheath pipe 4 or the new pipe 1 is inserted is
The length is such that one 0 can be lowered, and the length is approximately the same as the pit 12 described above. In this pit 15, when inserting the sheath pipe 4 etc. into the underground 2,
An impact type propulsion device 9 is attached to the pressing head 8 to assist the pulling force by the traction means 6 and to apply an impact to smooth the insertion into the underground 2. An air compressor 16, which is a supply source of compressed air for operating the impact propulsion device 9, is installed on the ground near the pit 15. In addition, in this pit 15, the connection of the sheath pipe 4 to be inserted into the ground, the connection of the new pipe 10 that follows, and the connection of the retraction rod 17 constituting the retraction means 11 are also performed.

A wire 18 is hung around a pin shaft 8a provided at the tip of the pressing head 8, and the pressing head 8 moves forward when the jack 5 is extended. The main body 8A of the pressing head 8 has a conical shape, and its outer diameter is approximately equal to the outer diameter of the sheath tube 4. As a result, when inserting the sheath pipe 4 into the underground 2, its end face can be pushed in with the main body 8A, and when inserting the new pipe 10, the new pipe 10
Secure insertion space. Note that this pressing head 8
The tip of the above-mentioned impact type propulsion device 9 is fitted into the
The impact force of the striking element (not shown) that reciprocates inside the
It is possible to act on the sheath tube 4 via the pressure head 8.

On the other hand, among the sheath pipes 4 inserted into the underground 2, the leading end of the sheath pipe 4A shown in FIG.
A cutter 19 for cutting the old pipe 3 is provided. In this example, as shown in FIG. 3a, the upper and lower ends of the cutter body 19A are fixed inside the sheath tube 4, and the cutting edge 19a cuts the old tube 3 shown by the imaginary line in the left-right direction. It is becoming possible to do this. The wire 18 is passed through the hole 20 passing through the cutter body 19A, and as the jack 5 expands, the sheath pipe 4 is inserted into the ground 2 via the traction rod 7, the wire 18, and the cutter body 19A. Incidentally, the cutting edge 19a may be horizontal as shown in FIG. 3b, or may be formed only on the left and right or top and bottom portions by attaching a holding member 21 or the like. Furthermore, as shown in FIGS. 3c and d, the cutting edge 19a may be tilted forward or the third
As shown in FIG.
The sheath tube 4 may be preceded by the sheath tube 9a. In the case of such a cutter, the old pipe 3 can be cut or broken from the inner surface. In any case, it is sufficient that the cutting edge is located at a position where the old pipe 3 can be reliably cut and crushed.

With the re-laying device 1 having the above configuration, it is possible to bury the new pipe 10 while cutting and recovering the old pipe 3 in the following manner.

As shown in FIG. 2, a pit 12 is formed, and its soil surface is reinforced with concrete walls 14. Then, the traction rod 7 is inserted into the buried old pipe 3, and the traction rods 7 are successively connected by welding or the like until reaching the other pit 15. In the pit 15, a wire 18 is connected to the tip of the pulling rod 7, and the tip of the wire 18 is attached to the cutter body 19A of the leading sheath tube 4A.

On the other hand, in the pit 12, the tip of the traction rod 7 is attached to the jack 5 via a traction fitting 22. When the jack 5 is extended while taking the reaction force from the concrete wall 14, the sheath pipe 4A is pushed into the ground 2 by its traction force so as to be fitted and inserted into the old pipe 3, as shown in FIG. At this time, the cutting edge 19a of the cutter 19 cuts and breaks the old pipe 3 from the end surface. For example, the large and small fragments 3a broken in the left and right direction are placed in the space 23 on the side of the cutter body 19a.
[See FIG. 3a], the soil is taken into the sheath pipe 4A together with the soil around the old pipe 3. Note that the jack 5 with the maximum stroke of the jack 5 is reduced, and a spacer 25 is inserted between the concrete wall 14 and the press fitting 24. The jack 5 is extended again, and this is repeated to insert one sheath tube 4A.

The jack 5 is reduced in size and the spacer 25 is also completely removed. The next sheath tube 4 without a cutter is lowered into the pit 15, and a threaded portion (not shown) formed at its tip is screwed into a threaded portion at the rear of the leading sheath tube 4A. After that, the same operation as described above is repeated by extending the jack 5 and so on. In this way, when the pulling means 6 pulls the tip of the leading sheath tube 4A, the straightness of the sheath tube 4 is extremely high, and the work of laying a new tube 10 at the position where the sheath tube 4 is removed in the later process is also possible. It becomes easier. In addition, Figures 2 and 4
As shown by the imaginary line in the figure, if the pressing head 8 is pressed after the sheath pipe 4 and the impact propulsion device 9 is attached and activated, the cutting of the old pipe 3 by the cutter 19 will reciprocate internally. This becomes even easier due to the impact force of the striker.

As shown in FIG. 5, when the leading sheath tube 4A reaches the pit 12, the series of insertions of the sheath tubes 4 is completed. At this time, all the fragments 3a of the old pipe 3 and the soil around them are contained in the sheath pipe 4, but a space corresponding to the internal space volume of the old pipe 3 is left inside the sheath pipe 4. ing. The cutter 19 and wire 18 are removed by cutting the tip of the sheath tube 4A, and the shortened traction rod 7 is also removed from the traction fitting 22.
From the pit 12, the traction rod 7 is inserted into the sheath tube 4 with a space left, and is extended toward the pit 15 while being successively joined.

In the pit 15, as shown in FIG. 6, a wire 18 is connected to the tip of the pulling rod 7, and the pin shaft 8
The conical surface of the pressure head 8 is applied to the rear end of the sheath tube 4 via a. After the impact type propulsion device 9 is attached as necessary, the wire 26 and the retracting rod 17, which are the retracting means 11, are installed after the pressing head 8.
The new pipe 10 is attached via a backing plate 27 or the like. The jack 5 is extended in the same way as when the sheath pipe 4 is inserted into the ground 2, and the pressing head 8 is inserted into the sheath pipe 4.
The new pipe 10 is inserted while pushing out the debris 3a and excavated soil contained therein. The outer diameter of the pressing head 8 is approximately the same diameter, either slightly larger or slightly smaller than the outer diameter of the new pipe 10;
The new tube 10 is smoothly inserted into the space after the sheath tube 4 has been removed.

When one new pipe 10 enters the underground 2, the sheath pipe 4 and the traction rod 7 are moved to the pit 12 side by the length of the new pipe 10, and the debris 3a
The towing rod 7 is removed from the jack 5 and removed by cutting or the like, and the tip of the towing rod 7 is reattached to the jack 5. In the pit 15, remove the cover plate 27 of the new pipe 10 inserted into the ground, lower the next new pipe 10A into which the retractable rod 17A has been inserted, and remove the tip of the retractable rod 17A, as shown in Fig. 1. It is connected to the rear end of the preceding retractable rod 17B with a connecting fitting or the like. The preceding new pipe 10B and the following new pipe 10A are connected, a backing plate 27 is attached to the rear part, and they are secured to the retractable rod 17A. In this way, when new pipes 10 are added and inserted one after another, all the old pipes 3 that have become fragments 3a along with the sheath pipe 4 and the surrounding soil are pushed out, and the new pipes 10 are buried in the positions. It goes without saying that if the impact propulsion device 9 is driven by compressed air supplied through a hose 28 connected to the air compressor 16, the removal operation will be easier.

According to such a resurfacing method, the sheath pipe 4 is covered with debris 3.
Since it encloses the old pipe 3 that has become a, the sheath pipe 4 is inserted while maintaining its straightness, and the old pipe 3 does not remain in the underground 2, and if the fragments 3a of the old pipe 3 remain. Damage to the new tube 10 that may occur is avoided. Since the outer diameter of the new tube 10 is approximately equal to the outer diameter of the sheath tube 4 or the outer diameter of the pressing head 8, no void is created around the new tube 10.

Incidentally, in the above example, jacks are mainly used to push the sheath tube, new pipe, etc., but it is also possible to use jacks in combination with an impact type propulsion device, or by using only an impact type propulsion device. Depending on the location where the pipe is to be buried, the soil quality, etc., the device that generates the pushing force may be selected and used as appropriate. In addition, if the new pipe 10 is considerably larger than the old pipe 3, the diameter of the sheath pipe 4 should also match the diameter of the new pipe 10, but the sheath pipe 4 should be slightly larger than the old pipe 3. , the diameter of the pressing head 8 may be increased in accordance with the diameter of the new pipe 10.

FIG. 7a shows an example in which a rotary cutter 19 is adopted, and as shown in FIG. 7b, the cutter roller 29 supports the side surface of a support body 31 that protrudes forward from a support member 30 fixed to the leading sheath tube 4A. It is supported by the plate 32. Note that the vertical height of the cutter rollers 29, 29 is larger than the inner diameter of the old pipe 3, and the cutter rollers 29, 29 are designed to break the old pipe 3 from the inner surface.

The wire 18 is inserted into the support body 31 whose axial center is a space, and the sheath tube 4A is pulled through the pin 33 of the support member 30 shown in FIG. 7a. At this time, the cutter roller 29 cuts the old pipe 3 by rotating as a result of being pulled by the jack 5 or by being driven by a motor (not shown). Incidentally, as shown in FIG. 7c, the wire 18A may be attached to the pin 33 so that the press head 8 can be pulled at the same time, or the cutter 1 may be pulled at the same time.
9 may be attached so as to protrude forward of the sheath tube 4A.

FIGS. 8a to 8f are process diagrams in the second invention,
By the relining device 1 equipped with the cutter 19, the sheath pipe 4 is
is inserted halfway into the ground and the old pipe 3 is cut.After that, while burying the new pipe 10, the sheath pipe 4 is pushed out to the other pit 12, and the remaining old pipe 3 is cut in the meantime. It consists of the process of

Jack 5 in pit 12 shown in Fig. 8a
and the cutter 19 in the sheath tube 4A in the pit 15.
are connected via a traction rod 7 and a wire 18 that pass through the old tube 3. When the jack 5 is extended, the tip of the sheath pipe 4A fits over the old pipe 3 and is inserted into the underground 2. At the same time, the old pipe 3 is cut by the cutter 19 shown in FIG. 8b, and the sheath is removed. Pipe 4A is fragment 3a
It progresses while collecting soil that has formed around the old pipe 3. When most of the sheath tube 4A is inserted, the subsequent sheath tube 4 is connected to the rear end at the pit 15,
After the pulling rod 7 protruding into the pit 12 is cut off, its tip is attached to the jack 5 again. The sheath tubes 4 are sequentially inserted, and when the first sheath tube 4A reaches the intermediate position between the two pits 12 and 15, the insertion of the sheath tubes 4 is stopped for the time being. At this time, the sheath pipe 4 accommodates the fragments 3a of the cut old pipe 3 and the soil surrounding it, but since there was a space in the old pipe 3, the outer diameter of the old pipe 3 Some space remains within the sheath tube 4, although this varies depending on the size, wall thickness, and inner diameter of the sheath tube 4. Therefore, as long as there is space left to accommodate the remaining old pipe 3 and the soil around it, it is possible to accommodate them without adding any more sheath pipes 4. That is, in the present invention, the sheath pipes 4 are inserted one after another until a space with an internal volume capable of accommodating the fragments 3a of all the old pipes 3 to be cut and the soil to be excavated around the old pipes 3 is provided. Then, the sheath pipe 4 is no longer added. This is because all the fragments 3a of the old tube 3 can be taken in until the leading sheath tube 4A reaches the pit 12. In other words, if the inside of the sheath tube 4 is filled with debris 3a etc. before reaching the pit 12,
The remaining old pipe 3 and the surrounding soil will be pushed out by the front of the sheath pipe 4A and the excavated soil stored there, which will cause the ground to collapse, but this can be avoided and The number of sheath tubes 4 used can be reduced.

Therefore, as shown in FIG. 8d, a pressing head 8 is applied to the rear part of the sheath pipe 4 of the pit 15 together with an impact propulsion device 9 which is glued as necessary, and the new pipe 10 can be towed at the rear part. can be attached to. As the jack 5 is extended, the impact propulsion device 9 is also operated as required, and the cutting of the old tube 3, the insertion of the sheath tube 4, and the burying of the new tube 10 are performed simultaneously as shown in FIG. 8e. When the pressing head 8 reaches the pit 12, the sheath tube 4 and the debris 3a it contains are removed.
etc. are taken out into the pit 12, and the burial of the new pipe 10 is completed as shown in FIG. 8(f). In addition, Figure 8a
Although the pressing head 8 to which the impact-type propulsion device 9 is attached is not attached in the examples to c, it goes without saying that the impact force generated by the pressing head 8 may be utilized.

In the example shown in FIG. 9, a cutter 19 having a cutter roller 29 is used, but regardless of the form of the cutter 19, in FIGS. 9a and b and FIGS. 1
8A, the new pipe 10 can be inserted in the state shown in FIGS. 9c and 9d by pulling the pressing head 8 that will be attached subsequently.

[Brief explanation of drawings]

Fig. 1 is an overall longitudinal cross-sectional view of the buried pipe re-laying method of the present invention being carried out, Fig. 2 is an explanatory diagram of the operation in the first invention, and Fig. 3a is the - of Fig. 2.
Fig. 3b is a front view of a different cutter, Fig. 3c is a side view of a cutter with a different shape, Fig. 3d is a view taken from the - line of Fig. 3c, Fig. 3e is a side view of an example in which the cutter is attached to the front end of the leading sheath tube, Figures 4 to 6 are operation explanatory diagrams, and Figure 7
Figure a is an explanatory diagram of the operation when a cutter roller is adopted, Figure 7b is a view taken along the - line in Figure 7a, and Figure 7c is a side view of a different example of how the cutter roller is installed.
Figures 8 and 9 are explanatory diagrams of the operation in the second invention, Figure 10 is a sectional view of an example in which the conventional underground piping replacement method is applied, and Figure 11 is an explanatory diagram of the operation of the second invention. It is a state diagram in which the pipe is bent at the connection part. 2...Underground, 3...Old pipe, 3a...Fragment, 4...
...sheath pipe, 10... new pipe.

Claims (1)

[Scope of Claims] 1. A method for replacing old pipes by removing old pipes buried underground and inserting new pipes in the buried position of the old pipes to replace the old and new pipes, A sheath pipe with an inner diameter larger than the outer diameter is fitted over and inserted into the old underground pipe, and at the time of insertion, the entire old pipe is cut and accommodated, and the sheath pipe and the cut old pipe are pushed out. ,
A method for replacing buried pipes characterized by inserting and laying new pipes. 2. In the method of replacing old pipes buried underground by removing old pipes and inserting new pipes in the buried position of the old pipes to replace the old and new pipes, The sheath pipe with the sheath pipe is externally fitted and inserted into the old underground pipe, and the old pipe is cut at the time of insertion, and the sheath pipe accommodates the cut old pipe, and
It is inserted until it has a space with an internal volume that can accommodate the fragments of all the old pipes and the soil to be excavated around the old pipes, and the tip of the sheath pipe has not yet severed all the old pipes. A buried pipe characterized in that the uncut old pipe is cut while advancing the sheath pipe, and at the same time, the new pipe is inserted and laid while pushing out the sheath pipe, the cut old pipe, and excavated soil. Resurfacing method.