JP3232501B2 - Double pipe buried method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double pipe precedent burial method for burying a main pipe of a gas pipe, for example, under a road, and in particular, does not require lining in a section where a permanent work zone cannot be secured on a main road. To reduce the cost of burying pipes and shorten the construction period.

[0002]

2. Description of the Related Art Conventionally, for example, a pipe burial method of burying a main pipe of a gas pipe underground of a main road, firstly, on a road in which a main pipe is to be buried, with a groove width larger than a pipe diameter of the main pipe in advance. Excavating a main injection groove having a predetermined depth, for example, a length of 170 m,
Steel sheet piles are driven into both sides of the main pipe insertion groove for earth retaining, and a steel sheet pile is secured between the steel sheet piles at predetermined intervals by shoring, and the main pipes adjacent to each other in the main pipe insertion groove are connected. At the part where the edge to be located is located, the width of the groove is widened and set as a meeting place in the working area, and steel sheet piles are also driven into the meeting place, and earth retaining is carried out, and a shoring is carried out. Thereafter, for example, the main pipe having a length of 12 m is suspended by a crane from the section start point of the main pipe introduction groove to the section end point one after another, and the main pipes adjacent from the section start point are centered and then joined. The welded ends are joined at the meeting place by welding, and after welding, they are subjected to welding inspection, and welding and inspection are repeated one after another until the section end point. When the main pipe is laid in the main pipe insertion groove in such a manner as to be integrated by welding, soil is buried back in the main pipe insertion groove, and the embedding of the main pipe is completed.

[0003]

In the conventional pipe burying method as described above, a main pipe charging groove of a predetermined length is excavated on a road which is an area where the main pipe is to be buried, and the main pipe charging groove is excavated. A plurality of main pipes are installed from the section start point to the section end point, adjacent main pipes are welded one after another from the section start point to the section end point, the welding inspection is performed, and the main pipe is inserted into the main pipe insertion groove. After the pipes are laid together by welding, the soil is buried back in the mains entrance groove to complete the embedding of the mains, so bury the mains on the road where the mains should be buried. For example, if it takes one week as a construction period, if there is a section of a place where a permanent work zone cannot be secured, such as an intersection of the road, a factory facing the road, a store, an entrance of a parking lot, and the like, a person enters and exits the section. Or allow the car to run Therefore, lining must be performed to cover the main slot in the section with a steel plate, and the lining has sufficient strength compared to the steel sheet pile used for the main slot in terms of safety. Since lining is required, lining is costly and requires extra time for lining, which leads to a longer construction period for burying pipes.

The present invention has been made to solve such a problem, and the area where the main pipe is to be buried is a road, and there is a section where the permanent work zone cannot be secured on the road. However, it is an object of the present invention to obtain a double pipe advance burial method that does not require lining, reduces the cost of burying pipes, and shortens the construction period.

[0005]

According to the double pipe precedent burial method of the present invention, a sheath pipe having a larger diameter than the main pipe is buried in a section where a permanent work zone cannot be secured in an area where the main pipe is to be buried. A plurality of sheath pipes are installed in the sheath pipe embedding groove, and these sheath pipes are connected to each other by a sheath pipe joint band. And a first main pipe having a mooring tool at a tip thereof on a plurality of rollers installed in a main pipe insertion groove provided at one end of the sheath pipe. Then, the first main pipe is suspended on a pipe suspending device installed at a meeting place arranged in parallel with the main pipe introduction groove at one end side of the sheath pipe, and on the outer periphery of the suspended main pipe, Attach a piping smoother made of hard synthetic resin consisting of a band and a number of protrusions provided on its outer surface A main pipe charging / suspending step, and installing in a pipe drawing groove provided on the other end side of the sheath pipe in a mooring tool of a first main pipe suspended by the pipe hanging device and having a piping smoother attached thereto; A rope mooring step of mooring the drawn-in rope of the drawn pipe pulling-in device, charging a second main pipe into the main pipe charging groove, and suspending the second main pipe by the pipe hanging device. A main pipe welding step of welding to the first main pipe, and operating the pipe retraction device to pull a pull-in rope to connect the first main pipe to the second main pipe and the first main pipe. A main pipe drawing-in step of pulling the welded part of the main pipe into the sheath pipe so as to be located at an end of the meeting place; and a main pipe charging / suspending step from a third main pipe to an n-th main pipe. The first main pipe is formed in a pipe-ingoing groove of a sheath pipe by the welding step and the drawing-in step. It reaches the end portion, n
The procedure is repeated in order until the second main pipe is located at the end of the sheath pipe at the meeting place side, so that a plurality of main pipes connected by welding are inserted into the sheath pipe.

In the present invention, in a region where the main pipe is to be buried, in a section where a permanent working zone cannot be secured, a sheath pipe having a predetermined length for burying a sheath pipe having a pipe diameter larger than the main pipe is buried. A trench is excavated, a plurality of sheath tubes are installed in the sheath tube embedding groove, and these sheath tubes are connected to each other by a sheath joint band, and then the sheath tube is buried by burying earth and sand in the sheath tube embedding groove. Therefore, the connection between the sheath pipes can be performed in a very short time, and the embedding work time of the sheath pipes is excavated in the conventional groove,
In this groove, multiple main pipes are installed.These main pipes are welded together, inspected, coated, covered with earth and sand, and the main pipe is buried. Therefore, the number of cases where lining is required is reduced, and when the section where the permanent work zone cannot be secured is short, it is possible to restore the same day, so there is no need to provide lining. Becomes

[0007] After the embedding of the sheath tube is completed, the first main tube is charged into the main tube charging groove, and the main tube is then placed in a meeting place located next to the main line charging groove. In the hall, the second main pipe is then inserted into the main slot, and the end of the second main pipe having most of the main slot and the pipes of the hall are suspended in the hall. Welding is performed with the end of the first main pipe suspended on the suspension device, and then the first main pipe suspended on the welded pipe suspension device is welded at the joint. Is drawn into the sheath tube by the pipe drawing device so as to be positioned at the end of the main pipe, and the main pipe charging / suspending step, the welding step, and the drawing step are performed from the third main pipe to the n-th main pipe. The first main pipe reaches the end of the sheath pipe on the side of the pipe drawing groove, and the n-th main pipe is the end of the sheath pipe on the meeting place side. It is repeated repeatedly until it is located at the position, and multiple main pipes connected by welding are inserted into the sheath pipe, so that pipe work can be intensively performed separately from civil engineering work. If the mains in the mains slot were suspended by the pipe lifting device and the mains were to be welded to the mains newly inserted in the mains slot, the main Welding inspection of the welded part located at the end can be performed, and welding and welding inspection can always be performed in the same place. Therefore, there is no need to carry the welding equipment and the inspection equipment, and the welding work efficiency is reduced. Significantly improved.

Further, in the main pipe charging / suspending step, the outer circumference of the main pipe suspended by the pipe suspension device installed at the meeting place is
By attaching a piping smoother made of a hard synthetic resin consisting of a band and a number of protrusions provided on its outer surface, when the main pipe is pulled by a pipe retraction device, the main pipe directly contacts the sheath pipe. The contact area with the sheath tube is reduced and the sliding resistance is reduced as compared with the case where the tube is retracted, and the pulling force of the main tube by the tube drawing device is reduced.

Further, a moving pulley may be attached to a mooring tool provided at the tip of the first main pipe.
By using one moving pulley, the pulling force of the main pipe by the pipe retraction device can be reduced to one half of that in the case of directly pulling the main pipe. It is effective when pulling in.

[0010] Further, after a plurality of main pipes connected by welding are inserted into the sheath pipe, a filler may be filled between the sheath pipe and the main pipe. With such a configuration,
Since the main pipe is buried under the ground, and the sheath pipe is provided around the main pipe, it is not necessary to provide a conventional protective iron plate. Further, when the occupation position of the gas pipe is less than 3 m from the public-private boundary, it is necessary to install a protection-side iron plate. However, by using the sheath tube, the protection-side iron plate is not required.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a process diagram showing the steps of a double pipe preceding embedding method according to an embodiment of the present invention, and FIG. 2 is a sheath pipe joint used in the double pipe preceding embedding method. FIG. 3 is a sectional view of a sheath pipe joint band, FIG. 4 is a longitudinal sectional view of a main pipe insertion groove, FIG. 5 is a longitudinal sectional view of a meeting place, and FIG. 6 is piping in a sheath pipe. It is sectional drawing which shows the state in which the main pipe | tube which attached the smoother was inserted. Next, a double pipe preceding burying method according to an embodiment of the present invention will be described with reference to the drawings.

First, the step of embedding the sheath tube will be described.
In order to bury the sheath pipe 1 which is a steel pipe having a diameter larger than the main pipe in advance in the section 2 where the permanent work zone cannot be secured in the area where the main pipe as the gas pipe is to be buried, for example, the length is 83 m.
Then, a sheath pipe embedding groove having a width of 1400 mm and a depth of 2600 mm is excavated. Next, for example, 14 sheath pipes 1 each having a diameter of 800 mm and a length of 6 m are inserted into the sheath pipe embedding groove from the starting point side to the end point side by a truck equipped with a crane. After setting the height of the sheath tube 1, the connecting portions 3a are connected to each other with the bolts 4 to connect the adjacent sheath tubes 1 to each other using a pair of split sheath joint bands 3 shown in FIG. As shown in FIG. 2, an integrated sheath tube 1 is installed in a sheath tube embedding groove 2. Thus, the sheath tube 1 is inserted into the sheath tube burying groove 2.
Is installed, earth and sand are buried in the upper portion of the sheath tube 1 except for both ends of the integrated sheath tube 1, and as shown in FIG. 1A, a section where the sheath tube 1 cannot secure a permanent working zone. 2 buried.

In the section 2 where the permanent work zone cannot be secured, the sheath pipes 1 are buried by connecting the sheath pipes 1 to each other with the sheath pipe joint band 3 and then backfilling the soil into the sheath pipe embedding groove. Therefore, the connection between the sheath pipes 1 can be performed in a very short time, and the embedding work of the sheath pipes 1 requires excavating a conventional groove, installing a plurality of main pipes in the groove, and connecting these main pipes. Inspection after welding, coating and coating, and then backfilling the earth and sand, greatly shortening the method compared to the method of burying the main pipe. Therefore, the number of cases where lining should be performed is reduced, and when the section 2 in which the permanent work zone cannot be secured is short, it is possible to recover the same day, and it is not necessary to provide lining. Becomes

Next, the step of inserting the main tube through the sheath tube will be described. First, working grooves are provided on both sides of the integrated sheath tube 1. That is, a meeting place 6 slightly longer than the length of one main pipe 5 and a book adjacent to the meeting place 6 and slightly longer than the length of one main pipe 5 are shown on the left side in FIG. A pipe introduction groove 7 is provided. The meeting place 6 is provided with a pipe hanging device 8. As shown in FIG. 5, the pipe suspension device 8 includes a plurality of H-shaped steel supports 11 supported on columns 10 provided along lightweight steel sheet piles 9 provided on both sides of the meeting place 6.
I-shaped steel rails 12 fixed to the rails, a plurality of Plenty trucks 13 running on the rails 12, and each Plenty truck 1
3 and a chain blow 14 and a chain blow 1
4 and a tube support band 15 suspended from the tube support band 4. In addition, light steel sheet piles 9 are provided on both sides of the main pipe introduction groove 7, and as shown in FIG. And a pipe receiving roller 17 is provided at the bottom of the main pipe introduction groove 7.

Further, as shown in FIG. 1, a pipe lead-in groove 20 is provided on the right side of the integrated sheath tube 1. Light steel sheet piles are also provided on both sides of the pipe drawing groove 20, supports are provided between the light steel sheet piles, and a pipe drawing device 21 is provided at the bottom of the pipe drawing groove 20. The pipe retraction device 21
The pull-in rope 22 includes a pull-in rope 22, a mooring device 23 for mooring one end of the pull-in rope 22, and a mechanism for pulling the other end of the pull-in rope 22, for example, a chill hole and a rope winding device 24.

Next, after inserting the main pipe into the main pipe insertion groove,
A process until the main tube is inserted through the sheath tube will be described.
First, as shown in FIG. 1 (a), the first main pipe 5 is temporarily placed on a pipe receiving roller 17 in a main pipe insertion groove 7 by using an integrated hanging apparatus (not shown). I do. A cap 25 having a hanging metal fitting 26 is attached to the tip of the first main pipe 5, and a pulling movable pulley 28 is connected to the hanging metal fitting 26 via a shackle 27. Next, as shown in FIG. 1A, the first main pipe 5 temporarily placed on the pipe receiving roller 17 is rolled toward the meeting place 6, and the pipe hanging device 8 installed in the meeting place 6. Suspended on a plurality of tube support bands 15
And run to the welding position. Thereafter, the pull-in rope 22 of the pipe pull-in device 21 provided in the pipe pull-in groove 20 is wrapped around the moving pulley 28 of the first main pipe 5. By using the moving pulley 28, the pipe retraction device 2
The pull-in force 1 is used to connect the pull-in rope 22 to the hanging fitting 2 of the main pipe 5.
It takes only half the force of pulling by mooring directly to 5. In addition, the pull-in rope 22 is connected to the hanging bracket 26
May be moored directly.

Thereafter, the second main pipe 5 is set in the main pipe introduction groove 7, and the second main pipe 5 and the pipe suspending device 8 are installed.
First main pipe 5 suspended on the pipe support band 15
Are centered by an internal clamp (not shown), and then externally welded by a welding machine (not shown) as shown in FIG. The (n-1) + n-th joint is inspected and coated simultaneously with the (n +) (n + 1) -th welding, and is provided on the outer periphery of the main body 5 shown in FIG. A piping smoother 30 formed of a hard synthetic resin having a large number of projections 32 formed at specified intervals,
For example, they are mounted at a pitch of 2 m. Attaching the piping smoother 30 to the outer periphery of the main pipe 5 in this way protects the coating of the main pipe 5 when the main pipe 5 is pulled by the pipe retraction device 21 and at the same time, the main pipe 5 is attached to the sheath pipe 1. As compared with the case of direct contact, the contact area with the sheath tube 1 is reduced and the sliding resistance is reduced, and the friction coefficient of the piping smoother 30 is low. Because it's easy. When the welding is completed, the rope winding device 24 of the pipe drawing-in device 21 is operated as shown in FIG.
The first main pipe 5 is drawn into the sheath pipe 1 so that the welded portion with the second main pipe 5 is located at the meeting place 6.

From the third main pipe 5 to the fourteenth main pipe 5, the main pipe 5 is inserted into the main pipe insertion groove 7, suspended by the pipe suspension device 8, and the main pipes 5 are connected to each other. As shown in FIG. 1D, the first main pipe 5 reaches the end of the sheath pipe 1 on the device housing groove 20 side, and the fourteenth main pipe 5 is pulled into the sheath pipe 1 by welding. The procedure is sequentially repeated until the pipe 5 is located at the end of the sheath pipe 1 at the meeting place side, so that 14 welded main pipes 5 are inserted into the sheath pipe 1. The third main pipe 5 to the fourteenth main pipe 5 are respectively connected to the next main pipe 5.
When welding is performed at the left end of the meeting place 6, the welded part performed before that is subjected to welding inspection at the right end of the meeting place 6,
At the same time, the coating layer and the piping smoother 30 are attached to the main pipe 5 located at the meeting place 6. As described above, at the meeting place 6, the main pipes 5 are welded to each other at one end,
At the other end, a weld inspection of the welded portion of the main pipe 5 is performed,
Since welding and inspection can always be performed in the same place, there is no need to carry a welding device and an inspection device, and the work efficiency of these devices has been significantly improved.

In comparison with the conventional example, such a welding operation will be described in detail. In the conventional method, when the steps of piping, welding, inspection and coating of the main pipe are completed, the next main pipe is connected to the welded main pipe. Since the steps of piping, welding, inspection, and coating are performed, and such steps are repeated one after another, for example, for one main pipe, 0.5 hour for main pipe, one hour for welding,
Assuming that it takes 1 hour for inspection and 0.5 hour for coating and covering, a total of 3 hours, welding work in normal burial can be performed only once or twice a day, if the working time per day is 7 hours. However, in the double pipe precedent burial method according to the embodiment of the present invention, the civil engineering work and the plumbing work are separated, and the piping work of the main pipe 5 is performed on the sheath pipe 1 buried by the civil engineering work. Work time is 0.5 hours for main pipes by performing station welding, 1.0 hours for welding, inspection and coating,
A total of about 2 hours, 0.5 hours for retraction, 1 weld
The welding can be performed three to four times a day, and high-efficiency welding can be performed.

After the main pipe 5 is drawn into the sheath pipe 1 in this way, as shown in FIG. 6, the space between the sheath pipe 1 and the main pipe 5 is filled with cement bentonite 33 as a filler. I do. In this filling, the mouths of the sheath tube 1 and the main tube 5 are closed with a mold, for example, a shrink tube, a confirmation port is provided at the top of one end of the sheath tube 1, and the other end of the sheath tube 1 is provided. The cement bentonite 33 is filled from the filling port, and the filling is completed when the cement bentonite 33 comes up to the confirmation port. When the main pipe 5 is drawn into the sheath pipe 1 and the cement can be filled with cement bentonite 33, the meeting place 6
The pipe pull-in device 8 is taken out from the pipe, the pipe pull-in device 21 is pulled out from the pipe pull-in groove 20, and the earth and sand are back-filled in the meeting place 6, the main pipe charging groove 7, and the pipe pull-in groove 20, and the double pipe leading embedding method is completed. . As described above, after the plurality of main pipes 5 connected by welding are inserted into the sheath pipe 1, the filler is filled between the sheath pipe 1 and the main pipe 5 because the sheath pipe 1 and the main pipe 5 are filled with the filler. This is because the presence of the filler between the main pipe 5 makes the same state as the main pipe 5 is buried in the ground, and the presence of the sheath pipe 1 around the main pipe 5 It is no longer necessary to provide a conventional protective iron plate, and in some cases, a protective iron plate. The reason why cement bentonite 33 was used as the filler is that it has excellent filling properties, for example, fluidity.

[0021]

As described above, according to the present invention, in a region where the main pipe is to be buried, in a section where a permanent working zone cannot be secured, a sheath pipe having a pipe diameter larger than the main pipe is buried. Excavating a sheath buried pipe groove of a predetermined length, installing a plurality of sheath pipes in the sheath buried pipe groove, connecting these sheath pipes with a sheath pipe joint band, and then backfilling the sheath buried pipe groove with earth and sand. Since the sheath pipes are buried, the connection between the sheath pipes can be performed in a very short time, and the embedding work of the sheath pipes requires excavating a conventional groove, and a plurality of main pipes are provided in the groove. Inspection after welding these main pipes to each other, applying coating and coating, and then backfilling the earth and sand to bury the main pipe. If the section where the permanent work zone cannot be secured is short, it can be restored on the same day. Provided need no longer, since the lining work and time associated therewith becomes unnecessary, an effect that can be reduced reduction and shortening of the construction period of the cost of pipe burying.

Further, after the embedding of the sheath pipe is completed, the first main pipe is charged into the main pipe charging groove, and the main pipe is thereafter placed in a meeting place arranged in parallel with the main pipe charging groove. In the hall, the second main pipe is then inserted into the main slot, and the end of the second main pipe having most of the main slot and the pipes of the hall are suspended in the hall. Welding is performed with the end of the first main pipe suspended on the suspension device, and then the first main pipe suspended on the welded pipe suspension device is welded at the joint. Is drawn into the sheath tube by the pipe drawing device so as to be positioned at the end of the main pipe, and the main pipe charging / suspending step, the welding step, and the drawing step are performed from the third main pipe to the n-th main pipe. The first main pipe reaches the end of the sheath pipe on the side of the pipe drawing groove, and the n-th main pipe is the end of the sheath pipe on the meeting place side. It is repeated repeatedly until it is located at the position, and multiple main pipes connected by welding are inserted into the sheath pipe, so that pipe work can be intensively performed separately from civil engineering work. If the mains in the mains slot were suspended by the pipe lifting device and the mains were to be welded to the mains newly inserted in the mains slot, the main Welding and inspection equipment can be carried out because welding inspection and coating of the welded part located at the end can be performed, and welding and inspection of the welded part can always be performed in the same place. This eliminates the need and has the effect of significantly improving the welding work efficiency.

Further, in the main pipe charging / suspending step, the outer circumference of the main pipe suspended by the pipe suspending device installed at the meeting place,
A piping smoother made of a hard synthetic resin consisting of a band and a number of protrusions provided on the outer surface is attached.When pulling the main pipe with a pipe retraction device, the main pipe is directly attached to the sheath pipe. Compared to the case of contact, it protects the coating and coating of the main pipe, reduces the contact area with the sheath pipe and reduces sliding resistance, and the pipe smoother has a low coefficient of friction. This has the effect of reducing the pulling force of the tube.

Further, since the movable pulley is attached to the mooring tool provided at the tip of the first main pipe, the pulling force of the main pipe by the pipe retraction device is one-half that of the case where the main pipe is directly pulled. This is effective only when a plurality of connected main pipes are drawn in, and also has an effect that the pipe drawing-in device can be reduced in size.

Further, after a plurality of welded main pipes are inserted into the sheath pipe, a filler is filled between the sheath pipe and the main pipe, so that the main pipe is buried in the ground. By providing a sheath tube around the surroundings, it is possible to eliminate the need to provide a conventional protective iron plate.

[Brief description of the drawings]

FIG. 1 is a process diagram showing a process of a double-pipe pre-burial method according to an embodiment of the present invention.

FIG. 2 is a front view showing a state in which a sheath pipe used in the double pipe preceding embedding method is connected by a sheath pipe joint band.

FIG. 3 is a sectional view of a sheath pipe joint band.

FIG. 4 is a longitudinal sectional view of a main pipe charging groove.

FIG. 5 is a vertical sectional view of a meeting place.

FIG. 6 is a cross-sectional view showing a state where a main pipe with a piping smoother attached is inserted into a sheath pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sheath pipe 2 Sheath pipe embedding groove 3 Sheath pipe joint band 5 Main pipe 6 Meeting place 7 Main pipe insertion groove 8 Pipe hanging device 17 Pipe cradle roller 20 Pipe drawing groove 21 Pipe drawing device 22 Pull rope 26 Hanging fitting )

Continuation of the front page (72) Inventor Kiyotaka Ishimori 5-6-23-403, Tsunashimahigashi, Kohoku-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Naomasa Takada 1-14-8 Omorinaka, Ota-ku, Tokyo Bears Sankei 302 (72) ) Inventor Kazuyuki Ota 5-24 Miharucho, Yokosuka City, Kanagawa Prefecture (72) Yoshiki Aizawa 1-25-13 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa Prefecture (72) Inventor Takayuki Shinozaki 2- Togane, Togane-shi, Chiba Prefecture 29 (72) Inventor Hiroya Kishino 3-28-70-410, Minamisenju, Arakawa-ku, Tokyo (72) Inventor Takafumi Takada 2-15-6, Kamedarijaku, Mitaka-shi, Tokyo (72) Inventor Issey Suzuki, Katsushika-ku, Tokyo Takasago 3-2-7-116 (56) Reference JP-A-63-189531 (JP, A) JP-A-6-129187 (JP, A) JP-A-7-268853 (JP, A) JP-A-8 −158426 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) E02D 29/10 E02B 9/06 E02F 5/10 F16L 1/038 F16L 1/024

Claims (3)

(57) [Claims] 1. In a region where a main pipe is to be buried, in a section where a permanent working zone cannot be secured, a sheath pipe burying groove of a predetermined length for burying a sheath pipe having a pipe diameter larger than the main pipe is excavated. A plurality of sheath pipes are installed in the sheath pipe embedding groove, and after connecting these sheath pipes to each other with a sheath pipe joint band, the sheath pipe is embedded in the sheath pipe embedding groove to embed the sheath pipe, and the sheath pipe embedding step, A first main pipe having a mooring tool at its tip is loaded onto a plurality of rollers provided in a main pipe loading groove provided at one end of the sheath pipe, and then a main pipe feeding groove is placed at one end of the sheath pipe. The first main pipe is suspended on a pipe suspension device installed at a meeting place located side by side, and a belt and the outside thereof are provided around the suspended main pipe.
Formed with hard synthetic resin consisting of a number of protrusions provided on the surface
A main pipe loading / suspending step of attaching the formed piping smoother; and a first main pipe mooring tool suspended by the pipe hanging device and having the piping smoother attached thereto, at the other end side of the sheath pipe. A rope mooring step for mooring a pull-in rope of a pipe pull-in device installed in a provided pipe pull-in groove, and charging a second main pipe into the main pipe charging groove, and connecting the second main pipe to the pipe A main pipe welding step of welding to a first main pipe suspended on a suspension device; and operating the pipe retraction device to pull a drop rope and connect the first main pipe to a second main pipe. A main pipe drawing-in step of pulling the welded portion between the main pipe and the first main pipe into the sheath pipe so as to be located at an end of the meeting place; and the third main pipe to the n-th main pipe, Main pipe loading / suspending process, the welding process, and the retracting process Were repeated until the first main pipe reached the end of the sheath pipe on the side of the pipe drawing groove, and the n-th main pipe was located at the meeting place end of the sheath pipe, and was welded and connected to the inside of the sheath pipe. A double pipe pre-burial method characterized by inserting a plurality of main pipes. 2. A moving pulley is attached to a mooring tool provided at a tip of the first main pipe.
Double pipe prior burial method as described. 3. After inserting the plurality of weld connected mains to the sheath tube, claim 1 or 2, characterized in that the filler is filled between the sleeve pipe and the main pipe Double pipe prior burial method as described.