JP3373396B2 - Propulsion method and pipe joint structure - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to water supply, gas,
The present invention relates to a non-open cutting propulsion method in which a plurality of propulsion pipes in a fluid transportation pipe used for sewerage or the like are sequentially added and propelled into the ground, and a pipe joint structure used in the construction method.

[0002]

2. Description of the Related Art Conventionally, when constructing a buried pipeline such as a ductile cast iron pipe, it has been common to dig the ground and lay it. This is called an excavation method.

However, in recent years, it has become difficult to cut off traffic due to the excavation method because the traffic volume has increased not only on main roads but also on general roads. Therefore, as shown in FIG. 9 (a), only the starting pit P and the reaching pit Q are excavated, and the underground W is horizontally excavated from the starting pit P by the excavating blade R, or the pipe A is press-fitted, and the pipe A is inserted. A so-called propulsion method, in which A is sequentially added and pushed by the jack B, is generally used.

As a pipe joint structure used in this propulsion method, as shown in FIG.
In the state in which the expanded ring-shaped lock ring 3 is installed inside, the insertion port 2 of the other tube A is inserted, and the insertion port 2
The flange 4 provided on the entire circumference of the outer surface of the above is brought into contact with the end surface of the receiving port 1. After this insertion, first, the lock ring 3 is screwed with the set bolts 3a at evenly spaced positions around the lock ring 3 to press-contact with the insertion ports 2, and the bolts 4a are inserted at equally spaced positions around the flange 4 so that the end face of the receiving port 1 is inserted. Screw into.

Next, the rubber ring 5 and the split ring 6 are inserted between the outer surface of the insertion opening 2 and the inner surface of the receiving opening 1, and the pressing ring 7 is applied to the inner surface of the receiving opening 1 and the bolts around the pressing ring 7 are inserted. 7a
Insert the connecting rod 8 into the head. In this state, when the bolt 7a is rotated and retracted, the rear end of the connecting rod 8 comes into contact with the inner peripheral concave wall 1a of the receiving port 1, and thereafter the push wheel 7 advances to move the split ring 6 and the rubber ring 5 together. The inner surface of the receiving opening 1 and the outer surface of the insertion opening 2 are sealed by pressing. Then, a lining material of the same quality as the lining 9 on the inner surface of the pipe A, for example, mortar 9a is provided on the rear portion of the push wheel 7.
To fill.

By these operations, a pipe joint is constructed, and in this state, the other propulsion pipe A is moved from the other propulsion pipe A side.
Then, it is propelled to the side for piping (laying) (Fig. 9 (b)). At this time, the fastening portion by the bolt 4a serves as a propulsive force transmitting portion, and the insertion opening 2 and the receiving opening 1, that is, both tubes A, A are integrally propelled. In the figure, D is exterior concrete, and 4b is a rib for reinforcing the flange.

In this pipe joint structure, when a stretching force in the pipe axial direction is applied to the pipe A due to an earthquake or the like, as shown in FIG.
Is broken, the insertion opening 2 slides with respect to the receiving opening 1, absorbs the expansion and contraction, and the protrusion 2a welded to the outer surface of the insertion opening 2 comes into contact with the lock ring 3 to prevent the insertion opening 2 from coming off. Is done. Further, Japanese Patent Laid-Open No. 8-135843 discloses a pipe joint structure in which the end face of the insertion port 2 is brought into contact with the inner concave wall 1a of the receiving port 1 to propel it, and in this structure, the lock ring 3 is used. It is said that the expansion and contraction of the pipe joint portion is absorbed by sliding in the annular groove on the outer peripheral surface.

[0008]

The contact between the flange 4 and the end surface of the receiving opening 1 and the end surface of the inserting opening 2 and the inner concave wall 1a of the receiving opening 1 are made.
With any of the propulsion means for contacting with each other, when the propulsion is completed, the contact is maintained. That is, the insertion opening 2 is not inserted into the receiving opening 1 any further. Therefore, in the event of an earthquake, not only the extension force but also the compression force will work, so the extension 2
Although there is no amount of compression force that allows movement in the same direction, if excessive force is applied, thrust will occur at the relevant contact part and the flange mounting part or insertion end There is a risk that the insertion part of the pipe will be destroyed.

[0009] By the way, in the excavation method, it is possible to use expansion type earthquake resistant joints and to pipe while securing the amount of expansion and contraction for each joint part, and the joint part expands and contracts even if the ground changes due to an earthquake or the like, Can absorb ground movement.

Further, at the time of propulsion, the propulsive force is similarly exerted by the contact between the flange 4 and the end surface of the receiving opening 1 or the contact between the end surface of the insertion opening 2 and the concave wall 1a of the receiving opening 1 and the curved propulsion portion. At locations containing large ridges, etc., an unbalanced load is applied to the thrust transmission part, that is, local stress concentration occurs,
The flange 4 and the end face of the insertion port 2 may be damaged.

Further, the meandering prevention is ensured by fastening a plurality of circumferential bolts 4a inserted through the flange 4, but it is not sufficient at a place where a large rake is included, and a more effective meandering preventing structure is desired. It is rare.

The first object of the present invention is to disperse the propulsion force transmitting portion so that the joint portion of the pipe laid in the propulsion method can be allowed to move back and forth in the axial direction of the pipe. This is the second problem, and more reliable prevention of meandering is the third problem.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned first problem, according to the present invention, after the propulsion pipe reaches the reaching hole, the leading propulsion pipe is fixed and the rearmost propulsion pipe is fixed. By pulling back each propulsion pipe, between each propulsion pipe,
The propelling pipes can be moved back and forth in the axial direction of the pipe without being separated.

In this way, even if an expansion / contraction force acts in the axial direction back and forth due to an earthquake or the like, as each pipe moves in the axial direction back and forth, the expansion force is absorbed and the pipe joint is destroyed. Is suppressed as much as possible.

In order to solve the above-mentioned second problem, the present invention is a pipe joint structure in which a propelling force is exerted by abutting a flange and a receiving end surface, in which a receiving projection is formed on the inner surface of the receiving opening and an outer surface of the insertion opening is formed. When the other propulsion pipe is inserted into the one propulsion pipe and the flange comes into contact with the receiving end face, the insertion protuberance also comes into contact with the receiving protuberance to generate propulsive force. I took part in it.

As described above, in addition to the contact between the flange and the receiving end face, the contact force between the receiving protrusion and the insertion protrusion causes a propulsive force, that is, the receiving protrusion and the insertion protrusion protrude. If it becomes a transmission part, an eccentric load at a portion including a curved propulsion part or a large rake is reduced as much as possible, and damage to the pipe joint portion can be suppressed as much as possible.

In order to achieve the above-mentioned third object, the present invention is a pipe joint structure in which a propulsive force is exerted by the abutment of a flange and a receptacle, in which a meandering prevention ring is fitted on the outer peripheral surface of the receptacle. When the flange comes into contact with the end face of the insertion opening, the meandering prevention ring is pressed by the front surface of the flange and fitted between the inner surface of the reception opening and the outer peripheral surface of the insertion opening.

As described above, when the meandering prevention ring is fitted to the inner peripheral surface of the receiving opening and fitted to the outer peripheral surface of the opening, the receiving opening and the inserting opening are integrated to effectively suppress the meandering.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION As an embodiment of the invention for achieving the above-mentioned first object, in a pipe joint structure for propelling a flange in contact with a receiving end face, a pull-back bolt that breaks with a tensile force more than required When the other propelling pipe is pulled back, the flange moves the pull-back bolt a required length and contacts the bolt head, and then one of the propelling rods is pushed. A configuration for transmitting a pullback force to the tube may be adopted.

According to this pipe joint structure, a plurality of propulsion pipes are sequentially added to the ground in the starting pit from the starting pit toward the reaching pit, and the propulsion pipe reaches the reaching pit, With the leading propulsion pipe fixed, pull the rearmost propulsion pipe so that at each pipe joint, the flange slides on the pullback bolt and contacts the bolt head, and then pulls back to one of the propulsion pipes. The force is transmitted to form the contractable length of both tubes by the sliding length of the flange.

Therefore, when an expansion and contraction force acts on the pipe due to an earthquake or the like, the pullback bolt is broken by the extension force of a required value or more, and the insertion port slides on the receiving port to absorb the extension. On the other hand, the compressive force is absorbed by sliding the insertion opening within the interval corresponding to the pullback length.

As an embodiment of the invention for achieving the above first and second objects, in the above embodiment, a receiving projection is provided on the inner surface of the receiving opening, and a protruding projection is provided on the outer surface of the receiving opening. , A lock ring in a diameter-expanded state is provided outside the receiving projection on the inner surface of the receiving opening, and the other propulsion tube is inserted into one propulsion tube, and when the flange comes into contact with the receiving end surface, the insertion is performed. The mouth protrusion abuts the mouth protrusion and bears a part of the propulsion force.The lock ring is pressed by the screwing of the bolt from the outer surface of the mouth to reduce the diameter, and is pressed against the outer peripheral surface of the mouth to propel the other side. When the pipe is pulled back and the flange comes into contact with the head of the pullback bolt, the insertion port protrusion may be located in the middle of the lock ring and the receiving protrusion.

In this structure, the amount of movement within the gap between the lock ring of the insertion port projection and the receiving port protrusion becomes the absorption width of the expansion and contraction of the pipe, and the lock ring of the insertion port protrusion or the contact with the receiving port protrusion causes the receiving ring to move. Prevents slipping out of the mouth or excessive insertion of the insertion opening.

In this structure, if the ring which fits the inner surface of the receiving port is provided on the front surface of the flange, the above-mentioned problem 3 can be achieved.

With the pipe joint structures according to the embodiments of both of the above inventions, in the same way as described above, a plurality of propulsion pipes are sequentially added and propelled into the ground from the starting pit toward the reaching pit. After the propulsion pipe reaches the reaching shaft, pulling the last propulsion pipe with the leading propulsion pipe fixed, the flange slides on the pullback bolt at each pipe joint and the bolt head Then, the pulling back force is transmitted to one of the propulsion pipes to form a contractible length of both pipes by the sliding length of the flange, and the expansion and contraction of the pipes is absorbed by the formation.

[0026]

[Embodiment 1] An embodiment of a pipe joint structure is shown in FIGS. 2 to 5, and the same reference numerals as those used above denote the same components. In this example,
First, not the conventional seal (FIG. 10) that is made by the rubber ring 5 that is mounted after the insertion of the insertion slot 2, but the inner surface groove 11 of the receiving slot 11.
A rubber ring (packing) 15 fitted to a is used for sealing. The rubber ring 15 is attached before inserting the insertion opening 12, and then the insertion opening 12 is inserted into the receiving opening 11.

In this way, with the seal structure in which the insertion port 12 is simply inserted, as in the pipe joint structure of FIG. 10, an operator enters the pipe A after the insertion port 2 is inserted and the rubber ring 5 is inserted. ,
The workability is improved because it is not necessary to attach the push wheel 7 or the like. In addition, the diameter is φ70, which does not allow workers to enter and work.
The propulsion method is possible even for a pipe A having a medium or small diameter of 0 mm or less.

In the middle of the inner surface of the socket 11, the socket projections 16 are formed all around the circumference.
Insertion projections 17 are formed on the entire outer surface of the insertion opening 12, respectively. As shown in FIG. 3, when the flange 4 of the insertion opening 12 comes into contact with the end surface of the receiving opening 11, both projections 16 and 17 are formed.
Also contact the flange 4 and the end face of the receiving port, and bear the propulsive force by the contact between the projections 16 and 17. The protrusions 16 and 17 are formed continuously over the entire circumference, and may be formed integrally with the pipe A at the same time or by welding.

Pullback bolt 1 inserted through the flange 4
3 is longer than the conventional one, and as shown in FIG.
When the rear propulsion pipe A is pulled, the flange 4 is
The pipe A is retracted until it comes into contact with the head of the pipe, and thereafter, both pipes A, A are pulled back together through the bolt 13. This action is performed in each pipe joint.

By this pulling back, the insertion port projection 17 is separated from the receiving projection 16 and the lock ring 3 and the receiving projection 16 are separated.
Located in the middle of. That is, as shown in FIG. 4, when the pullback amount is L ₁ , the distance between the protrusions 16 and 17, the distance L ₂ between the lock ring 3 and the insertion opening projection 17, the tip of the insertion opening 12 and the inner concave wall 11b of the receiving opening 11 are shown. The relationship of L ₁ = L ₂ <L ₃ occurs between the intervals L ₃ of. This relationship is generated in each pipe joint portion, and the gap L ₂ becomes the expandable length between the pipes A, the expansion and contraction of the pipe A is absorbed, and
Due to the distance L ₃ , the tip of the insertion port 12 and the inner wall 1 of the receiving port 11
Between 1b, even if there is a movement of the insertion opening 12 toward the rear of the receiving opening 11, the distance is allowed. L ₂ is 1% or more of the effective length of the tube A.

The lock ring 3 has a shape shown in FIG. 5 (a) and is always given a diametrical expansion force. When the lock ring 3 is fitted in the groove of the receiving port 11 as shown in FIG. Most of them are depressed to prevent the insertion of the insertion opening 12 having the protrusion 17 from being hindered. After the insertion, as shown in FIG.
When the set bolt 3a is screwed in, the lock ring 3 is reduced in diameter and pressed against the outer peripheral surface of the insertion port 12, and when the two pipes A, A of the joint portion are pulled out, the insertion port projection 1
A locking portion is formed to engage 7 and prevent further slipping out. Further, the lock ring 3 integrates the two pipes A, A (the insertion opening 12 and the receiving opening 11) and suppresses the meandering to some extent.

Further, a meandering prevention ring 18 shown in FIG. 5B is fitted on the front surface of the flange 4, and when this ring 18 is given a diameter reducing force and fitted into the insertion opening 12, The diameter reducing force firmly fits the insertion opening 12. The cross section of the ring 18 is shaped so as to fit snugly inside the tip portion of the receiving port 11. As shown in FIG. 3, when the flange 4 abuts the receiving end face, the contact force causes the ring 18 to move. It fits tightly between the receiving opening 11 and the insertion opening 12, and the receiving opening 11 and the insertion opening 12 are integrated with the lock ring 3 to prevent the meandering.

In the case of the curved pipe propulsion method, the meandering prevention ring 18 is not provided. Both rings 3, 18 are FC
A metal material having high strength and elasticity such as D, SS, SUS is used. Incidentally, the pull-back bolt 13 responds to the bending by the play in the through hole of the flange 4 when propelling the bending portion.

This embodiment is constructed as described above, and in order to lay it in the ground by the propulsion method, as shown in FIG. 1, as in the conventional case, it goes from the starting pit P to the reaching pit Q. In the starting pit P in the ground W, the propulsion pipe A is sequentially added, and the jack B is propelled and buried.

When the pipe A is replenished, as shown in FIG. 2, the insertion opening 12 fitted with the ring 18 is inserted into the receiving opening 11 provided with the rubber ring 15, and as shown in FIG. 17 is brought into contact with the receiving projection 16, the flange 4 is brought into contact with the receiving end surface, the ring 18 is fitted onto the inner surface of the receiving opening 11, and the pull-back bolt 13 is screwed into the receiving end surface. Promote in this state.

If the propulsion pipe A reaches the reaching pit Q as shown in FIG. 1 (a) as the continuous propelling is advanced, as shown in FIG. Propulsion tube A
Is fixed in the reaching pit Q, and the jack B is used to pull back the rearmost propulsion pipe A. As shown in FIG. 4, the pullback force causes the rear propulsion pipe A to retreat the length L ₁ with respect to the front propulsion pipe A in each pipe joint portion, as shown in FIG. 1 (b). A gap S is generated in the pipe joint portion. Installation is completed in this state. Since each pipe joint portion is in the state of FIG. 4, even if the pipe A expands or contracts in the axial direction of the pipe A due to an earthquake or the like as described above, the expansion and contraction of the bolt 13 due to the breakage of the bolt 13 and the movement of the protrusion 17 cause the expansion and contraction. Absorbed and also protrusion 1
The contact of 7 with the lock ring 3 or the protrusion 16 prevents the insertion opening 12 from slipping out or being pushed.

Assuming that the effective sectional area of the bolt 13 is A, the stress at the breaking point of the bolt 13 is σ, and the number of bolts is N, the constraint force F _B of the pipe joint portion by the bolt 13 is F _B = A · σ
・ N. In addition, the maximum tensile force when pulling back the pipe A with the jack B after the end of propulsion is F _J , and the tensile force in the axial direction of the pipe that must withstand during an earthquake is F _A (= 0.3 Dtf, D: nominal diameter m
m), the bolts 13 are selected so that they have the relationship shown in the following equation. F _j <F _B = A ・ σ ・ N <F _A

[0038]

[Embodiment 2] In this embodiment, as shown in FIGS.
Instead of the pullback bolt 13, a protruding contact portion 13a is formed on the entire circumference of the lock ring 3, and at the time of pullback, the insertion protrusion 17 is brought into contact with the contact portion 13a.
The propulsion pipe A on the rear side is made to move following the propulsion pipe A on the front side.

In this embodiment, the lock ring 3 is inserted into the groove 3 thereof.
Inserting the insertion port 12 into the receiving port 11 in the retracted state in b, and tightening the set bolt 3a as shown in FIG. 6, the contact portion 13a is brought into contact with the moving area of the insertion port protrusion 17.
To project. In this state, propulsion is performed in the same manner as in the past. When reaching the reaching pit Q, the rearmost propulsion pipe A is pulled back to bring the insertion port projection 17 into contact with the contact portion 13a in each pipe joint portion as shown in FIG. This state becomes the state shown in FIG.

In this state, when the pipe A expands and contracts back and forth in the axial direction of the pipe due to an earthquake or the like, as shown in FIG. 8, the insertion opening projection 17 bends or breaks the contact portion 13a. The lock ring 3 can be moved. That is,
The insertion port projection 17 is movable between the lock ring 3 and the receiving projection 16 to absorb the expansion and contraction of the pipe A.

In this embodiment, the pullback bolt 13
Can be provided. At this time, the contact of the insertion protrusion 17 with the contact portion 13a and the contact of the flange 4 with the head of the bolt 13 may be performed at the same time, or either one may be contacted earlier. it can.

[0042]

As described above, according to the present invention, the movement of the pipe in the axial direction of the pipe due to an earthquake or the like can be absorbed, and the damage of the pipe joint portion can be effectively prevented. That is, since the joint expansion and contraction amount can be secured in both the pulling-out direction and the pushing-in direction, even if the ground greatly changes due to an earthquake or the like, the joint can follow the ground change, and a more reliable earthquake-resistant pipeline can be constructed.

Further, a propulsive force deviation during propulsion is unlikely to occur greatly, and smooth propulsion can be performed. That is, since the propulsive force is dispersed and transmitted by the flange and the insertion protrusion, even if the propulsive force locally increases at the curved part or the rake during the propulsion work, the force applied to the flange can be suppressed to be small. It can be done and smooth promotion can be performed.

Further, by fitting the meandering prevention ring onto the inner surface of the receiving port, the receiving port and the insertion port in the pipe radial direction are firmly integrated, and the straightness at the time of propulsion can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a propulsion method of the present invention.

FIG. 2 is a sectional view of an essential part for explaining the operation of one embodiment of the pipe joint structure of the present invention.

FIG. 3 is a sectional view for explaining the operation of the same embodiment.

FIG. 4 is a sectional view for explaining the operation of the same embodiment.

FIG. 5 (a) is a front view of the lock ring of the embodiment,
(B) is a front view of the meandering prevention ring

FIG. 6 is a sectional view for explaining the operation of another embodiment.

FIG. 7 is a sectional view for explaining the operation of the same embodiment.

FIG. 8 is a sectional view for explaining the operation of the same embodiment.

FIG. 9 is an explanatory diagram of a conventional example of a propulsion method.

FIG. 10 is a sectional view of an essential part for explaining the operation of the conventional example.

FIG. 11 is a cross-sectional view of an essential part for explaining the same action.

[Explanation of symbols]

A propulsion pipe B original push jack E pipe fixing jig P start pit Q arrival pit W ground (underground) 1, 11 mouth 2, 12 insertion holes 3 lock ring 3a set bolt 4 Insertion flange 13 Pullback bolt 13a contact part 15 Rubber ring for seal 16 Mouth protrusion 17 Insert protrusion 18 Meandering prevention ring

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliographic data Sho 60-18190 (JP, U) Real development Sho 54-3623 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16L 1/024

Claims (6)

(57) [Claims] 1. The underground W from the starting pit P to the reaching pit Q
To, in said starting pit P, and a plurality of propulsion tube A, the promotion of one
Insert the insertion port 12 of the other propulsion pipe A into the socket 11 of the pipe A.
Then, while sequentially adding and promoting it, each pipe joint
In the pipe axial direction with respect to the insertion port 12 with respect to the receiving port 11
Required length within the range where the propulsion pipe A is not separated back and forth
In the pipe joint structure of the propulsion pipe A used for the propulsion method of laying so as to be movable, in a state in which the propulsion pipe A at the head is fixed after the propulsion pipe A reaches the reaching pit Q. , By pulling back the propulsion pipe A, pull back each propulsion pipe A ,
Propulsion pipe A with the insertion port 12 forward and backward with respect to the receiving port 11 in the axial direction of the pipe.
Within the required length that can move without being separated
Pipe joint structure, characterized in that was set to extent. 2. The pipe joint structure according to claim 1,
The flange 4 provided on the outer peripheral surface of the insertion port 12 is used as the receiving port 1
In contact with the end surface of the 1, a pipe joint structure of one of the propulsion tube A the propulsion pipe has been implementing the side A from the other propulsion tube A side, fitting a meandering prevention ring 18 to the insert opening 12 outer peripheral surface Wear
In the meandering prevention ring 18, the flange 4 has a receiving port 11
A pipe joint structure characterized in that, when it comes into contact with an end face, it is pressed against the front face of the flange 4 and is fitted between the inner face of the receiving port 11 and the outer peripheral face of the insertion port 12 to prevent meandering during propulsion. 3. A pipe joint structure according to claim 1 or 2, in contact with flange 4 provided on the upper Symbol inserting opening 12 outer periphery above Symbol receiving port 11 end face those, one from the other propulsion tube A side A pipe joint structure of the propulsion pipe A that is propelled by the propulsion pipe A, and a pull-back bolt 13 that breaks by a tensile force more than required at the time of an earthquake or the like is passed through the flange 4 and the receiving port 11
Screwed to the end face, when pulled back the other propulsion tube A, the flange 4 abuts on the bolt head to move the retraction bolt 13 in the tube joint, the inserted port
12 is the propulsion pipe A separated from the inlet 11 in the pipe axial direction
A pipe joint structure characterized by transmitting a pull-back force to one of the propulsion pipes A after reaching a middle of a required length capable of moving in a range that is not affected. 4. The pipe joint structure according to claim 3 ,
The receiving projection 16 is provided on the inner surface of the receiving opening 11 and the insertion projection 17 is provided on the outer surface of the insertion opening 12, and the receiving opening is provided.
11 Lock-li in the state where the diameter is expanded outside the socket projection 16 on the inner surface.
Between the socket projection 16 and the lock ring 3
The insertion opening projection 17 is located on the
By abutting on the mouth protrusions 16, the
The insertion on the top is blocked, and the insertion port protrusion 17
By contacting the lock ring 3, the insertion opening 12
Is prevented from further exiting, and the insertion port 12 is received.
11 The propulsion pipe A should be separated from the front and rear in the axial direction of the pipe.
It is designed to be able to move for the required length without
When the other propulsion pipe A is inserted into the one propulsion pipe A and the flange 4 comes into contact with the end face of the receiving port 11, the insertion port projection 17 also comes into contact with the receiving port projection 16 and the propulsive force is applied. Pipe joint structure characterized by carrying a part of 5. The underground W from the starting pit P to the reaching pit Q
To, in said starting pit P, and a plurality of propulsion tube A, the promotion of one
Insert the insertion port 12 of the other propulsion pipe A into the socket 11 of the pipe A.
Nde to propel while sequentially topped Rutotomoni, each pipe fittings
In the pipe axial direction with respect to the insertion port 12 with respect to the receiving port 11
Required length within the range where the propulsion pipe A is not separated back and forth
It is a propulsion method of laying so that it can move , after the propulsion pipe A reaches the reaching pit Q, with the leading propulsion pipe A fixed, pulling the last propulsion pipe A Pull back the propulsion pipe A, and at each pipe joint,
The above-mentioned insertion port 12 and the receiving port 11 are forward and backward in the axial direction of the pipe.
A of the required length that can move in the range that is not separated
A propulsion method characterized by making it in the middle . 6. A propulsion method comprising performing the propulsion method according to claim 5 with the pipe joint structure according to any one of claims 1 to 4 .