JP2000303779A - Small-bore propulsion machine, method for recovering leading pipe, and method for inserting leading pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-bore propulsion machine, a method for recovering a leading pipe, and a method for inserting the leading pipe, whereby the leading pipe can be propelled at reduced propulsion resistance and high accuracy with respect to a wide range of soil qualities from sand and conglomerate layers to bedrock layers and can be easily recovered to a starting vertical shaft through buried pipes laid in place and the recovered leading pipe or a new leading pipe can be inserted for re-boring into the buried pipes laid in advance. SOLUTION: A leading pipe C and an outer cylinder A are connected together, and the leading pipe C is advanced for digging while the diameter of a cutter head 6 is increased, so as to lay buried pipes 2 in sequence. To pull back the leading pipe C, the diameter of the cutter head 6 is reduced and the connection is undone, after which the force to pull back is imparted to the leading pipe C to pull it back into a starting vertical shaft. To perform re-boring work using the leading pipe C, the cutter head 6 is inserted into the outer cylinder A and connected thereto and its diameter is increased to advance the leading pipe C for digging.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small-diameter thruster used for laying a buried pipe, a method of recovering a front conduit provided in the small-diameter propulsion by pulling back and collecting the same, and a method of laying underground. The present invention also relates to a method for charging a front pipe into the buried pipe.

[0002]

2. Description of the Related Art As a conventional small-diameter thruster, there is used a small-diameter thruster having a leading conduit in which a cutter head is rotatably mounted at a front end portion of a trunk having substantially the same outer diameter as a buried pipe. I have. When laying a buried pipe with this small-diameter thruster, the cutter head is rotated, and a propulsion device installed in advance in the starting shaft is pressed against the rear end of the front pipe to extend the front pipe. Propelling force is transmitted, and the leading pipe penetrates the ground. Next, the propulsion device is contracted to connect the buried pipe to the rear end of the front pipe, and the propulsion device is pressed against the rear end of the buried pipe to extend the propulsion force to the front pipe via the buried pipe. introduce. By repeating this process, the buried pipes are sequentially connected to lay the buried pipes. When the laying work of the buried pipe is completed in this way, only the leading pipe exposed to the reaching shaft is collected from the reaching shaft. When the direction of the leading pipe deviates from the planned laying line during propulsion, it is general to correct the direction by swinging the leading pipe.

However, in such a small-diameter thruster, since the leading conduit cannot be recovered until it reaches the reaching shaft, if the reaching shaft cannot be constructed due to the circumstances around the place where the buried pipe is laid, the burial can be buried. There is a problem that pipes cannot be laid.

[0004] As a method of solving such a problem,
In Japanese Utility Model Registration No. 2537753 and Utility Model Registration No. 2559261, a small-diameter propulsion configured to reduce the outer diameter of a leading pipe to the inner diameter of a buried pipe and recover the leading pipe through a buried pipe to a starting shaft. Machine has been proposed.

However, these utility model registrations No. 25377
In the small-diameter thruster disclosed in JP-A-53-53 and Utility Model Registration No. 2559261, since the outer diameter of the leading pipe is smaller than the inner diameter of the buried pipe, a portion outside the inner diameter of the buried pipe is excavated. Instead, the buried pipe will be propelled, and the ground outside the inner diameter of the buried pipe will be compacted, which will increase the propulsion resistance and reduce the construction efficiency.

[0006] To deal with such problems,
JP-A-7-269284, JP-A-8-28414
No. 0 and JP-A-9-144485 disclose that the excavation diameter of the leading pipe is substantially the same as the outer diameter of the buried pipe, and that the starting pipe passes through the buried pipe while avoiding interference with the buried pipe. A small-diameter thruster configured to be retrievable on the side has been proposed.

In the small-diameter thruster 100 described in Japanese Patent Application Laid-Open No. 7-269284, as shown in FIG. The wedge-shaped slider 106 is mounted between the rear end portion of the holding member 102 of the crushable bit 101 and the outer tube 103 by moving the inner tube 105 forward and swingably attached.
Is provided at the tip of the inner tube 107. The wedge-shaped slider 106 is supported in a state where the wedge-shaped slider 106 is completely inserted and opened outward.
Is moved rearward to release the support of the crushable bit 101. This small-diameter thruster 100 is configured to be pulled back to the starting shaft while the support of the crushable bit 101 is released. In addition, this small-diameter thruster 100
Means that the entire inner cylinder 105 rotates and the excavated material is
08.

As shown in FIG. 11, a small-diameter thruster 110 described in Japanese Patent Application Laid-Open No. 8-284140 has an outer cylinder 113 provided on the outer circumference of a front conduit 112 provided with a cutter head 111 on the front surface. Is installed, and the pipe 1
The outer cylinder 12 and the outer cylinder 113 are connected by a shear pin that is sheared when a shear force equal to or more than a predetermined value acts. The outer diameter of the cutter head 111 is smaller than the inner diameter of the outer cylinder 113, and the earth and sand in front of the outer cylinder 113 is not excavated by the cutter head 111, but the inner circumferential surface at the tip of the outer cylinder 113 increases in diameter toward the tip. When the propulsive force is applied, it is sunk into the ground to introduce earth and sand into the front conduit 112. Also,
After the excavation by the small-diameter thruster 110, the shear pin is sheared by the pulling force applied to the leading conduit 112, and the connection between the outer cylinder 113 and the leading conduit 112 is released,
The leading conduit 112 is pulled back through the inside of the outer cylinder 113.

The small-diameter thruster 120 described in Japanese Patent Application Laid-Open No. 9-144485 has an outer peripheral bit 121 attached to the tip end as shown in FIG. 12, and has a plurality of spokes 122 that can bend toward the excavation surface. It comprises a cutter head 123 arranged in the radial direction, a front pipe 124 for rotatably mounting the cutter head 123 on the front surface, and an outer cylinder 125 arranged on the outer periphery of the front pipe 124,
When the cutter head 123 is rotated, the trajectory of the outer peripheral bit 121 is made substantially equal to the outer diameter of the outer cylinder 125, and when the shear force of a predetermined value or more acts on the leading conduit 124 and the outer cylinder 125, Are connected via a shear pin (not shown) which is sheared.

In this small-diameter thruster 120, the drawing force is transmitted to the leading conduit 124 after the excavation is completed, the shearing force acting on the shear pin increases, and when the shear pin reaches a predetermined value, the shear pin is sheared and the outer cylinder 125 And the connection with the leading conduit 124 is released. Then, the tip of the spoke 122 is
25, the spoke 122 is bent toward the excavation surface side by the subsequent withdrawal of the leading conduit 124, and the outer cylinder 12
5 is pulled back through the inside of the outer cylinder 125 while avoiding interference with the outer cylinder 125.

[0011]

However, the small-diameter thruster 10 disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-269284 has a problem.
In the case of 0, since the entire inner cylinder 105 rotates and cannot be bent, the direction cannot be corrected, and there is a problem that accurate construction is difficult. Further, since the excavated earth and sand is directly taken in from the opening 108, there is a problem that it is impossible to return the excavated earth and sand to the starting shaft while the earth and sand are stored in the inner cylinder. In addition, since there is no means for supporting the earth pressure in front of the cutter, it is not possible to cope with construction in an aquifer or highly collapsible soil.

In the small-diameter thruster 110 described in Japanese Patent Application Laid-Open No. 8-284140, the outer cylinder 113 is propelled by piercing the tip of the outer cylinder 113 into the ground. There is a problem that it is difficult to propel the outer cylinder 113 to a robust stratum such as a gravel layer. In addition, since the shear pin connecting the front pipe 112 and the outer cylinder 113 is sheared and the front pipe 112 is pulled back, there is a problem in that the front pipe 112 cannot be inserted into the outer cylinder 113 again and excavated.

On the other hand, in the small-diameter thruster 120 described in Japanese Patent Application Laid-Open No. 9-144485, since the excavation of earth and sand is performed by the outer peripheral bit 121 attached to the spoke 122, excavation of the gravel layer Is difficult. Further, the front pipe 124 and the outer cylinder 125
Is sheared to separate the leading conduit 124 and the outer tube 125 so that the leading tube 124 is pulled back. Therefore, the leading tube 124 once pulled back is inserted into the outer tube 125 again and connected. Since the diameter of the bent spoke 122 cannot be increased with respect to the face face, it is impossible to re-enter and re-enter the leading conduit 124.

The present invention has been made in order to solve such a problem, and it is possible to protrude a front pipe with low propulsion resistance and with high precision in a wide range of soil from a gravel layer to a bedrock layer. It is possible to easily recover the leading conduit to the starting shaft through the laid buried pipe, and to re-excavate by introducing the recovered leading pipe or a new leading pipe into the previously laid buried pipe. It is an object of the present invention to provide a small-diameter excavator, a method for collecting a leading pipe, and a method for charging a leading pipe.

[0015]

In order to achieve the above-mentioned object, a small-diameter thruster according to a first aspect of the present invention is connected to a tip of a buried pipe and has a diameter substantially equal to the outer diameter of the buried pipe. A small-diameter thruster comprising: an outer cylinder having an outer diameter of: and a front conduit whose rear portion is inserted into the outer cylinder when the buried pipe is laid. And a cutter head that can expand and contract its outer diameter,
(B) When laying the buried pipe, the outer diameter of the cutter head is enlarged so as to be substantially the same as the outer diameter of the buried pipe, and when the leading pipe is passed through the outer cylinder and the buried pipe, Expansion and contraction means for reducing the outer diameter of the cutter head to be smaller than the inner diameter of the buried pipe; and (c) connecting the front pipe and the outer cylinder when laying the buried pipe, and connecting the front pipe to the outer pipe. When passing through the cylinder and the buried pipe, there is provided a connecting means for releasing the connection and separating the front pipe and the outer cylinder.

In the present invention, the connecting pipe is connected to the outer pipe by the connecting means, and the outer diameter of the cutter head is expanded by the expanding / contracting means so as to be substantially the same as the outer diameter of the buried pipe (outer pipe). By applying the propulsive force to the outer cylinder, the propulsive force is transmitted to the leading conduit, and the buried pipe is sequentially added to the rear of the outer cylinder, thus laying the buried pipe. On the other hand, when the laying operation of the buried pipe is completed or when the laying work of the buried pipe is interrupted and the front pipe is pulled back, the connection between the front pipe and the outer cylinder is released by the connecting means, and the expansion and contraction means is used. After reducing the outer diameter of the cutter head to be smaller than the inner diameter of the buried pipe (outer cylinder),
When a retraction force is applied to the leading conduit, the leading conduit is pulled backward through the outer tube and the buried tube without interfering with the outer tube and the buried tube. Further, the leading pipe is put into the buried pipe and the outer cylinder under the ground, that is, the cutter pipe whose diameter is reduced is inserted into the outer pipe through the buried pipe, and the leading pipe is connected to the outer pipe by the connecting means. After connecting the tube and expanding the cutter head by the expanding / contracting means, the propulsion force is applied to the leading conduit, so that the burying pipe can be laid again.

According to the present invention, the outer diameter of the outer cylinder and the buried pipe are excavated by the cutter head, so that the outer cylinder and the buried pipe can be smoothly propelled. This has an effect that a buried pipe can be laid without difficulty in a robust stratum such as a bedrock or a gravel layer, for which propulsion has been difficult. In addition, after the laying of the buried pipe is completed, the leading pipe can be pulled back and collected, so that the reaching shaft conventionally required for collecting the leading pipe becomes unnecessary, and cost reduction and shortening of the construction period can be achieved. . Since the front pipe can be pulled back and inserted into an underground outer cylinder and the laying work of the buried pipe can be resumed, for example, repair of the front pipe or an underground obstacle occurs during the laying of the buried pipe. Even in such a case, it is not necessary to construct an intermediate shaft or the like, and the work of repairing the leading pipe and the work of removing the underground obstacle can be performed.

Next, in the method of recovering a leading pipe according to the second invention, the buried pipe is connected to the tip of the buried pipe and has an outer diameter substantially equal to the outer diameter of the buried pipe. A small-diameter thruster having an outer diameter that is substantially the same as the outer diameter of the pipe and having a front end provided with a scalable cutter head having an outer diameter smaller than the inner diameter of the buried pipe at the time of reducing the diameter so that the front pipe can be connected and separated. In the method for collecting the front pipe through the buried pipe laid using the method, the cutter head is reduced in diameter, and after the connection between the front pipe and the outer pipe is released, the tip of the outer pipe becomes The outer cylinder and the buried pipe are pushed in until reaching the approximate tip position of the cutter head, and then a retraction force is applied to the leading pipe to recover the leading pipe through the inside of the outer cylinder and the buried pipe. .

In the present invention, a buried pipe connected to the outer cylinder is laid in a tunnel having a diameter substantially equal to the outer diameter of the outer cylinder excavated by the cutter head in an enlarged state at the front end of the front pipe, When the front pipe is pulled back through the buried pipe, the outer cylinder and the buried pipe are propelled forward so as to cover in advance a cavity formed by the retraction of the front pipe, and then returned to the front pipe. Apply force and collect to starting shaft.

According to the present invention, since the upper portion of the cavity is covered by the outer cylinder and the buried pipe before the withdrawal of the leading conduit, the danger of collapse of the ground can be avoided, and the leading conduit can be collected safely. It works. In this way, there is an effect that the cost and the construction period can be reduced. In addition, since the cutter head excavates with the same diameter as the outer diameter of the outer cylinder, it can be applied to a robust stratum such as a bedrock or a gravel layer. Can be smoothly propelled until the tip position of the cutter head reaches the tip position of the cutter head.

In the method for recovering a leading pipe according to the third aspect of the present invention, the outer diameter of the buried pipe is increased when the diameter of the buried pipe is increased. It is laid using a small-diameter thruster with a front pipe equipped with a scalable cutter head that has an outer diameter smaller than the inner diameter of the buried pipe when the diameter is reduced. In the method of recovering the leading pipe through the buried pipe, the cutter head is reduced in diameter, and after the connection between the leading pipe and the outer cylinder is released, a chemical solution is injected in front of the leading pipe. A protective wall is formed by applying a retraction force to the leading conduit while retracting it by a predetermined amount, and thereafter collecting the leading conduit through the outer cylinder and the buried pipe.

In the present invention, a buried pipe connected to the outer cylinder is laid in a tunnel having a diameter substantially the same as the outer diameter of the outer cylinder excavated by the cutter head in an enlarged state at the front end of the front pipe, When the leading conduit is pulled back through the buried pipe, a chemical solution is injected into a cavity formed by pulling back the leading conduit. While the chemical is being injected, the front conduit is retracted by a predetermined amount (preferably to the outer cylinder tip position) to terminate the injection of the chemical, and then the front conduit is pulled back and collected.

According to the present invention, since the protective solution is formed by injecting the chemical solution into the cavity formed by pulling back the front pipe, the buried pipe can be reliably formed even on a spring ground or a highly collapsed ground. Laying and recovery of the leading conduit are possible, and can be adapted to a wider range of soil properties. Further, similarly to the effect of the second invention, there is an effect that the outer cylinder and the buried pipe can be accurately propelled with a small propulsion resistance.

In the method for recovering a leading pipe according to a fourth aspect of the present invention, the outer diameter of the buried pipe is increased when the diameter of the buried pipe is increased. It is laid using a small-diameter thruster with a front pipe equipped with a scalable cutter head that has an outer diameter smaller than the inner diameter of the buried pipe when the diameter is reduced. In the method of recovering the leading pipe through the buried pipe, the cutter head is reduced in diameter, and after the connection between the leading pipe and the outer cylinder is released, the tip of the outer pipe becomes the cutter head. Push the outer cylinder and the buried pipe until the tip position is reached, and then apply a retraction force to the front pipe while injecting a chemical solution in front of the front pipe to retreat a predetermined amount to form a protective wall. Inside and buried pipe Is characterized in that the collecting through.

In the present invention, when the front conduit is pulled back, the outer cylinder and the buried pipe are propelled forward so as to cover in advance the cavity formed by the retraction of the front conduit, and furthermore, the predetermined amount is set while the front conduit is being retracted. Is performed to form a protective wall. By doing so, for example, even in the case of spring ground or highly collapsed ground, the laying of buried pipes and the recovery of the leading pipe are possible, and the chemical solution injection section can be shortened. Shortening and cost reduction can be achieved. In addition, the same effect as the third invention can be obtained.

According to the fifth aspect of the present invention, there is provided a method for inserting a front pipe into a buried pipe laid in the ground and an outer cylinder connected to the tip of the buried pipe, the diameter of which is substantially the same as the outer diameter of the buried pipe when the diameter is expanded. An outer diameter, and a retractable cutter head having an outer diameter smaller than the inner diameter of the buried pipe at the front end when the diameter is reduced, and a method of charging a front pipe that can be connected to and separated from the outer cylinder. After the cutter head has inserted the leading pipe in a reduced diameter state so as to pass through the buried pipe, a pulling force is applied to the buried pipe to pull the outer cylinder back to a connection position with the leading pipe. The cutter head is connected to an outer cylinder, and the diameter of the cutter head is increased.

In the present invention, the leading pipe is introduced through the buried pipe and the outer cylinder, and the leading pipe and the outer pipe are connected to each other. The laying of the buried pipe can be resumed. Therefore, for example, even if repair of a front pipe or an underground obstacle occurs during the laying of a buried pipe, there is no need to construct an intermediate shaft, etc., and repair work on the front pipe and removal of underground obstacles Can be performed, and there is an effect that the construction cost can be reduced and the construction period can be shortened.

[0028] In the method for charging a front pipe according to the sixth invention, the inside diameter of the buried pipe and the outer cylinder connected to the tip of the buried pipe are substantially the same as the outer diameter of the buried pipe when the diameter is expanded. An outer diameter, and a retractable cutter head having an outer diameter smaller than the inner diameter of the buried pipe at the front end when the diameter is reduced, and a method of charging a front pipe that can be connected to and separated from the outer cylinder. After the cutter head is inserted so that the leading pipe in the reduced diameter state passes through the buried pipe, after expanding the diameter of the cutter head, or after expanding the diameter while excavating the cutter head, the leading pipe is connected to the outer cylinder. The leading pipe and the outer cylinder are connected by excavating to the connecting position of (1).

According to the present invention, similarly to the fifth invention, even if, for example, repair of a front pipe or an underground obstacle occurs during the laying of a buried pipe, the front pipe can be constructed without constructing an intermediate shaft or the like. Repair work and underground obstruction removal work can be performed, and there is an effect that the construction cost can be reduced and the construction period can be shortened.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, specific embodiments of a small-diameter thruster, a method for recovering a leading pipe, and a method for charging a leading pipe according to the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a leading pipe of a small-diameter thruster according to a first embodiment of the present invention. FIG. 2 is a sectional view taken along the line PP of FIG.

The small-diameter thruster 1 of the first embodiment has a buried pipe 2
An outer cylinder A having an outer diameter substantially the same as that of the outer cylinder A and connected to the tip of the buried pipe 2, a front pipe C connectable to and separable from the outer cylinder A, and disposed in a starting shaft (not shown) And a propulsion device (not shown) for applying a propulsive force to the leading conduit C by pressing the rear end face of the buried pipe 2.

The front pipe C has a buried pipe 2 and an outer cylinder A
A body 3 having an outer diameter smaller than the inner diameter of the body 3 is provided. The body 3 is divided into a front body 3a and a rear body 3b, and the front body 3a and the rear body 3b are rocked by a rocking jack (not shown). It is swingably connected by the moving part 4 and has a structure capable of correcting the propulsion direction. A cutter head 6 having a plurality of disk cutters 5 on the front side is provided forward of the front trunk 3a in the propulsion direction, and soil and the like are externally applied between the bulkhead 7 behind the cutter head 6 and the disk cutter 5. A take-in chamber 8 is provided. The cutter head 6 is rotatably supported on the front body 3a by a cutter head driving unit 6a provided in the front body 3a. In FIG. 1, the leading conduit C of the small-diameter thruster 1 is illustrated as being divided into two parts, front and rear.

An earth discharging device 9 for discharging earth and sand taken into the chamber 8 is provided through the body 3 to a position slightly behind the rear body 3b along the central axis thereof. The discharging device 9 comprises a screw conveyor 10 and a casing 11 thereof.
The zero screw shaft 12 is rotatable forward and backward around the axis by a drive motor 13 attached to the rear end.

The disk cutter 5 disposed on the outer peripheral portion of the cutter head 6 has a cross section substantially L which is pivotally supported by a bracket 15 projecting forward from the bulkhead 7.
It is supported by the distal end of the support member 14 having the shape of a letter, and is swingable from a position substantially equal to the outer diameter of the outer cylinder A to a position slightly closer to the center than the inner diameter of the outer cylinder A. The front side of the bulkhead 7 is closer to the base end than the corner of the support member 14 when the diameter of the cutter head 6 is expanded, that is, when the disk cutter 5 is swung to a position substantially equal to the outer diameter of the outer cylinder A. A stopper 16 is provided for holding the position of the disk cutter 5 by abutting the back surface. In the outermost part of the front surface of the stopper 16,
When the support member 14 is not in contact with the stopper 16, the gravel is prevented from being trapped between the back surface of the base end side of the support member 14 and the bulkhead 7 so that sand and gravel do not enter the tunnel shaft wall. A rubber 17 protrudes.

On the front surface of the cutter head 6, an expansion / contraction mechanism D for operating the swing of the disk cutter 5 to expand / contract the outer diameter of the cutter head 6 is provided. The expansion / contraction mechanism D is radially and radially projected from a slide case 20 in which the disk cutter 5 can swing back and forth along the outer periphery of a shaft 19 disposed at the center of the front surface of the cutter head 6. It is linked and connected via a link member 22 pivotally supported by the bracket 21. That is, when the slide case 20 is slid forward,
A pressing force is applied to the disk cutter 5 radially outward of the cutter head 6 via the link member 22 to enlarge the outer diameter of the cutter head 6 (shown by a solid line in FIG. 1). On the other hand, when the slide case 20 is slid rearward, a retraction force is applied to the disk cutter 5 via the link member 22 inward in the radial direction of the cutter head 6 to reduce the outer diameter of the cutter head 6. (Indicated by the two-dot chain line in FIG. 1).

The slide case 20 is connected to the front end of the screw shaft 12 via a ball joint 20a, and only the forward and backward movements of the screw shaft 12 are transmitted to the slide case 20 by the ball joint 20a. The rotation speed difference between the rotation of the cutter head 6 and the rotation of the screw shaft 12 is allowed.

The rear end portion of the casing 11 of the earth discharging device 9 is divided into front and rear portions, and the rear casing portion is fitted to the front casing portion so as to be slidable back and forth.
A slide case sliding jack 23 is attached to the casing portion divided into the front and rear portions so as to straddle the divided portion. Therefore, the screw shaft 12 is pulled back by the extension of the slide case sliding jack 23, and the screw shaft 12 is pushed forward by the contraction of the slide case sliding jack 23.

At the rear of the casing 11, an earth discharging pipe 24 connected to the excavated earth and sand discharge space between the screw shaft 12 and the casing 11 is connected.
4, a suction-side pipe 26 provided with a vacuum pump P <b> 1 that discharges excavated earth and sand backward through a switching valve 25;
A delivery-side pipe 27 having a pressure pump P2 for delivering a filler to the front surface of the cutter head 6 through the excavated earth and sand space is connected. The filler is a one-pack type solidifying agent whose curing time is adjusted so that it hardens after reaching the front of the cutter head 6 through the excavated earth and sand space.

At the rear end of the rear trunk 3b, a pair of upper and lower thrust transmitting members 30a and 30b made of a substantially arc-shaped plate are provided. As shown in FIG. 2, one end of each of the propulsion force transmitting members 30a and 30b is rotatably pin-coupled to each other, and the other end is connected via a jack 31. The propulsion force transmitting members 30a and 30b expand and contract in the radial direction.

Further, at the inner periphery of the rear portion of the outer cylinder A and at a position corresponding to the driving force transmitting members 30a and 30b, when the driving force transmitting members 30a and 30b are expanded in diameter, the driving force transmitting members 30a and 30b An engaging member 33 having an engaging groove 32 for engaging the outer peripheral portion of 30b is fixedly provided. In this manner, the jack 31 is extended so that the thrust transmitting members 30a, 30b
The outer cylinder A and the rear trunk 3b are connected to each other by pressing the rear end face of the buried pipe 2 to apply a propulsive force, Conduit C
Is provided with propulsion. Also, when the jack 31 is contracted to reduce the diameter of the thrust transmitting members 30a, 30b, the outer peripheral portions of the thrust transmitting members 30a, 30b are disengaged from the engaging grooves 32, and the outer cylinder A and the rear body The connection with 3b is released.

In order to lay the buried pipe 2 using the small-diameter thruster 1 constructed as described above, first, the front pipe C is inserted into the outer cylinder A.
The disk cutter 5 is pushed out in the radial direction of the cutter head 6 by pushing the screw shaft 12 forward to move the slide case 20 forward, thereby contracting the slide case sliding jack 23 to push the disk cutter 5 forward. To increase the diameter. Next, the thrust transmitting member 30
The outer cylinder A and the front conduit C are integrated with each other by engaging the engagement groove 32 of the engagement member 33 with the diameter increase of the a and 30b. In this manner, with the front cutter head 6 rotated, the rear end face of the outer cylinder A is pressed by the propulsion device installed in the starting shaft to apply a propulsive force to the leading conduit C, and Excavation is performed with a diameter substantially equal to the diameter, and the outer cylinder A penetrates into the ground.

Next, the buried pipe 2 is connected to the rear end face of the outer cylinder A. When the rear end face of the buried pipe 2 is pressed by the propulsion device, the buried pipe 2 is propelled to the leading conduit C via the buried pipe 2 and the outer cylinder A. Power is transmitted and excavation work is performed. Thus buried pipe 2
A new buried pipe 2 is successively added to the rear end face, and the digging operation is repeated to lay the buried pipe 2. During the excavation work, the discharging pipe 24 is connected to the suction pipe 26 by the switching valve 25, and the sediment taken in the chamber 8 is rotated by the forward rotation of the screw conveyor 10, and the excavated sediment discharging space of the discharging apparatus 9. Is supplied to the earth discharging pipe 24 and is sucked into the suction side pipe 26 by the operation of the vacuum pump P1.

FIG. 3 is an explanatory view for explaining a procedure for collecting the leading pipe C of the first embodiment in the starting shaft.

In the first embodiment, when the excavation work (laying work of the buried pipe 2) by the small-diameter propulsion device 1 is completed and the leading pipe C is collected in the starting shaft, or when the leading pipe C is stopped, the leading pipe C is stopped. When collecting in the starting shaft (FIG. 3 (a)), first, the slide case 20 is moved backward by extending the slide case sliding jack 23 and sliding the screw shaft 12 backward. Disk cutter 5
Is drawn toward the center of the cutter head 6 in the radial direction so that the outer diameter of the cutter head 6 is reduced to be smaller than the inner diameter of the outer cylinder A (FIG. 3B). After this, the jack 31
Is contracted to reduce the diameters of the propulsion force transmitting members 30a and 30b, and the connection between the outer tube A and the front conduit C is released, so that the distal end surface of the outer cylinder A is substantially at the same position as the distal end surface of the front conduit 2. Until then, the rear end face of the buried pipe 2 is pressed by the propulsion device to propel the outer cylinder A and the buried pipe 2 forward (FIG. 3C). continue,
The leading conduit C is pulled back (FIGS. 3D and 3E) and collected in the starting shaft.

By propelling the outer cylinder A and the buried pipe 2 forward in this manner, the cutter head 6 and the front trunk 3a of the front conduit C not covered by the outer cylinder A during the excavation work.
It is possible to cover the upper part of the cavity created by pulling the leading conduit C back to the part. Therefore, it is possible to avoid the danger that the ground collapses, and it is possible to safely recover the leading pipe. The pull-back procedure of the first embodiment is as follows.
This is effective for a ground with high ground strength or a ground that does not immediately collapse due to lack of water due to injection of a chemical solution or the like in advance.

According to the first embodiment, since the excavation work is performed by the disk cutter 5 provided in front of the cutter head 6, it is possible to cope with a wide range of soils such as gravel and bedrock. As a result, since the excavation having the same diameter as the outer diameter of the outer cylinder A is performed, the outer cylinder A and the buried pipe 2 can be smoothly propelled.

According to the first embodiment, the leading conduit C can be recovered in the starting shaft in a reusable state.
For this reason, for example, when exchanging the disk cutter 5 during the excavation work or when an obstacle that cannot be excavated appears during the excavation, the leading pipe C is temporarily collected in the starting shaft, and the cutter steel pipe work and the obstacle removal are performed. There is an effect that after the work is completed, the leading pipe C can be re-entered and re-excavated.

In the first embodiment, the leading pipe C and the outer cylinder A
However, the diameter of the cutter head 6 may be expanded after the leading conduit C and the outer tube A are connected, and the leading tube C and the outer tube A may be connected to each other. And the diameter expansion of the cutter head 6 may be performed simultaneously.

Further, in the first embodiment, the outer cylinder A and the buried pipe 2 disconnected from the leading pipe C by the propulsion device are propelled forward, but the invention is not limited to this. As shown in the schematic diagram of FIG.
Was a double tube structure, so as to push the slide jack 35 provided inside the cylinder A ₁ to the outside of the cylinder A ₂ forward, the tip of the inner cylinder A ₁ and the tip of the leading pipe C Position. In this case, the stroke of the slide jack 35 is not set to a necessary slide amount, but is pushed out by successively adding the spacers 36 with a short stroke.

Next, a method of recovering the leading conduit according to the second embodiment will be described. In the second embodiment, there is no difference from the first embodiment except that only the procedure for collecting the leading conduit C into the starting shaft is different. Hereinafter, the configuration common to the first embodiment will be described using the same reference numerals.

FIG. 5 is an explanatory view for explaining a procedure for recovering the leading conduit C of the second embodiment.

In the second embodiment, when the excavation work by the small-diameter thruster 1 is completed and the leading conduit C is collected in the starting shaft, or when the excavation is suspended and the leading conduit C is collected in the starting shaft, (FIG. 5A), the slide case 20 is moved rearward by extending the slide case slide jack 23 and sliding the screw shaft 12 rearward, and the disc cutter 5 is moved to the cutter head 6. The outer diameter of the cutter head 6 is reduced so as to be smaller than the inner diameter of the outer cylinder A by being retracted toward the center in the radial direction (FIG. 5).
(B)).

Next, the jack 31 is contracted to reduce the diameter of the propulsion force transmitting members 30a and 30b, and the connection between the outer cylinder A and the leading pipe C is released. Pull back. At the same time as the return of the leading conduit C, the switching valve 25 is connected to the delivery-side piping, and the screw conveyor 10 is connected.
Is rotated in the reverse direction to feed the filler material forward of the cutter head 6 (FIG. 5C).

After the hollow formed by the retreat of the front conduit C and the tip in the outer cylinder A are solidified by this filler (FIG. 5 (d)), the pump is stopped and the filler is stopped. Is finished, the leading conduit C is pulled back and collected in the starting shaft (FIG. 5 (e)).

According to the second embodiment, since the cavity formed by the retreat of the leading conduit C and the tip of the outer cylinder A are closed by the filler, the ground is a spring ground or a ground which has a strong collapse. Can be constructed reliably, and it is possible to cope with a wider range of soil properties.

According to the second embodiment, as in the first embodiment, the outer cylinder A and the buried pipe 2 can be propelled with a small propulsion resistance and with high accuracy. In addition, since the front pipe C is collected in a reusable state, the collected front pipe C can be re-introduced into the outer cylinder A and re-excavated.

In the second embodiment, a one-component type solidifying agent is used as a filler, but the present invention is not limited to this. For example, a two-component type solidifying agent can be used. In this case, for example, the screw shaft 12 is made hollow, and one of the two-liquid mixing type chemicals is supplied to the front of the cutter head 6 through the screw shaft 12, and the other chemical is supplied to the cutter head 6 through the excavated earth and sand discharge space. 6 in front of the cutter head 6 and 2
What is necessary is just to mix and harden the seed chemicals.

Next, a method of recovering the leading conduit according to the third embodiment will be described with reference to FIG. In the third embodiment, there is basically no difference from the first embodiment except that the configuration for injecting the filler into the cutter head 6 and the configuration of the outer cylinder A 'are different. Therefore, configurations common to the first embodiment will be described using the same reference numerals.

In the small-diameter thruster 1 'of the third embodiment, the filler passage pipe extends from a part of the outer periphery of the outer cylinder A' (the lower part in this embodiment) and from the front end to the rear end. A filler 40 is provided so that the filler is injected into the front of the cutter head 6 through the filler flow pipe 40. The rear part of the filler channel pipe 40 is disposed in the buried pipe 2, and the tip of the filler channel pipe 40 is connected to the outer cylinder A ′.
It is communicated with the tip inside. In addition, there is no need to provide the switching valve 25 on the downstream side of the discharge pipe 24,
4 is a suction side pipe 26 provided with a vacuum pump P1.
As long as they are connected.

The outer cylinder A ′ is connected to the
In order to secure the length of pulling back the leading conduit C while injecting the filler from 0, the length is set longer than the outer cylinder A of the small-diameter thruster 1 used in the first embodiment.

FIG. 6 is an explanatory view for explaining a procedure for recovering the leading conduit C of the third embodiment.

In the third embodiment, when the excavation operation by the small-diameter propulsion unit 1 'is completed in the same procedure as in the first embodiment, or when the excavation work is interrupted and the leading pipe C is returned to the starting shaft, ( 6A, first, the disk cutter 5 is pulled toward the center of the cutter head 6 in the radial direction, and the outer diameter of the cutter head 6 is reduced to be smaller than the inner diameter of the outer cylinder A '(FIG. 6B). Next, the jack 31 is contracted to reduce the diameter of the propulsion force transmitting members 30a and 30b.
Then, the outer tube A and the buried pipe 2 are propelled forward until the distal end surface of the outer tube A is substantially at the same position as the distal end surface of the front conduit 2 (FIG. 6C).

Next, while moving the leading conduit C backward,
The filler is sent out from the tip of the outer cylinder A to the front of the cutter head 6 through the inside of the filler channel pipe 40, and the filler is injected into the tip space of the outer cylinder A from the tunnel face to protect the filler. After forming the wall (FIG. 6 (d)), the injection of the filler is terminated and the leading conduit C is pulled back and collected in the starting shaft (FIG. 6 (e)).

According to the third embodiment, substantially the same effects as those of the second embodiment can be obtained. Further, since the amount of the filler to be injected can be reduced, the cost and the construction period can be reduced. Also, the filler flow pipe 4
Since 0 is provided on the outer peripheral portion of the outer cylinder A ′ and the size of the leading conduit C can be reduced, the present invention can be applied to laying a buried pipe having a smaller diameter.

In the third embodiment, the filler flow pipe 4
0, the leading pipe C is pulled back while the filler is being injected in front of the cutter head 6, but the present invention is not limited to this, and the reverse rotation of the screw shaft 12 is performed using the same small-diameter thruster 1 as in the first embodiment. While the filler is being injected by the above procedure,
It is also possible to pull back.

In each of the above embodiments, the cutter head 6
The connection between the leading pipe C and the outer cylinder A is released after the diameter of the cutter head 6 is reduced. However, the present invention is not limited to this, and the diameter of the cutter head 6 is reduced after the connection between the leading pipe C and the outer cylinder A is released. Alternatively, the connection between the leading conduit C and the outer cylinder A and the diameter reduction of the cutter head 6 may be performed simultaneously.

Next, a description will be given of a method of charging the leading conduit C according to the fourth embodiment. In the fourth embodiment, the same small-diameter thruster 1 used in the first embodiment and the second embodiment is used, and the small-diameter thruster 1 is buried through a buried pipe 2 laid underground. The leading pipe C is introduced into the outer cylinder A connected to the tip of the pipe 2. The configuration common to the first and second embodiments will be described using the same reference numerals.

FIG. 7 shows that the front pipe C of the fourth embodiment is connected to the outer cylinder A.
An explanatory diagram for explaining a procedure of charging the inside is shown.

In the fourth embodiment, the outer diameter of the leading pipe C having the cutter head 6 on the front surface is reduced by extending the slide case sliding jack 23 and sliding the screw shaft 12 backward. In a reduced state, the cutter head 6 penetrates through the buried pipe 2 and the outer cylinder A laid underground until the front surface of the cutter head 6 comes into contact with the tunnel face (FIGS. 7A and 7B).

Next, the outer cylinder A and the buried pipe 2 are pulled rearward so that the engaging groove 32 of the outer cylinder A is located at a position facing the propulsion force transmitting members 30a, 30b of the leading conduit C (FIG. 7 ( c)). Thereafter, the jack 31 is extended to engage the propulsion force transmitting members 30a, 30b with the engagement grooves 32, thereby integrating the leading conduit C and the outer cylinder A, and the slide case sliding jack 23 is moved. The outer diameter of the cutter head 6 is increased so that the outer diameter of the cutter head 6 becomes substantially the same as that of the outer cylinder A by contracting and sliding the screw shaft 12 forward (FIG. 7).
(D)). In this manner, the rear end face of the buried pipe 2 is pressed against the propulsion device while rotating the cutter head 6, and the propulsion force is transmitted to the leading conduit C to perform the re-digging work and the laying work of the buried pipe 2.

As described above, the leading pipe C can be connected to the outer cylinder A through the buried pipe 2 underground, and the leading pipe C can be re-excavated with the diameter of the front cutter head 6 expanded. When repairing the front pipe C or removing underground obstacles during excavation by the pipe C, the conventionally constructed intermediate shaft is unnecessary, so the construction cost can be reduced and the construction period can be shortened. This has the effect that it can be performed.

In the fourth embodiment, the diameter of the cutter head 6 is expanded after the pulled back outer cylinder A and the leading pipe C are connected. However, the present invention is not limited to this. The diameter of the cutter head may be increased at the same time as the outer cylinder A is pulled back.

Next, a description will be given of a method of charging the leading conduit C according to the fifth embodiment. In the fifth embodiment, the same small-diameter thruster 1 used in the first and second embodiments is used, and the buried pipe 2 passes through the buried pipe 2 laid underground. The leading pipe C is put into the outer cylinder A connected to the tip of the pipe. The configuration common to the first and second embodiments will be described using the same reference numerals.

FIG. 8 is an explanatory view for explaining a procedure for charging the front pipe C into the outer cylinder A according to the fifth embodiment.

In the fifth embodiment, the cutter head 6 is inserted deeper than the front end of the outer cylinder A connected to the front end of the buried pipe 2 laid underground.
A space having substantially the same diameter as the outer diameter of the outer cylinder A is formed in advance (FIG. 8A), and the leading conduit C having the cutter head 6 on the front surface is screwed by extending the slide case sliding jack 23. With the outer diameter of the cutter head 6 reduced by sliding the shaft 12 rearward, the cutter head 6 penetrates through the embedded tube 2 and the outer cylinder A so as to be disposed in the space (FIG. 8 (b)).

Subsequently, the slide head 23 is contracted to expand the cutter head 6 so that its outer diameter becomes substantially the same as the outer diameter of the outer cylinder A (FIG. 8).
(C)). Thereafter, excavation is performed while rotating the cutter head 6, and the propulsion force transmitting members 30a, 3
0b reaches the position where the engagement groove 32 of the outer cylinder A faces the engagement groove 32, the jack 31 is extended, and the thrust transmitting member 3
The leading conduit C and the outer tube A are integrated by engaging the engagement grooves 32 with the engagement grooves 32. Thus, as described above, the buried pipe 2
Then, the rear end face is pressed against the propulsion device, and the propulsion force is transmitted to the leading conduit C to perform the redigging operation and the laying of the buried pipe (FIG. 8D).

In the fifth embodiment, after the cutter head 6 has been placed in the space, the propulsion force transmitting members 30a and 30b are coupled to the engagement grooves 32 of the outer cylinder A, and the rear end of the front conduit C is connected. A propulsion tube (not shown) is sequentially added to the propulsion device, and the rear end face of the propulsion tube is pressed by a propulsion device to transmit a propulsion force. As another method of transmitting the propulsive force to the leading conduit C, as shown in a schematic configuration diagram of FIG. 4B, a slide jack 41 is attached to the inner periphery of the buried pipe 2 and the slide jack 41 is attached. The driving force may be transmitted to the front conduit 2 by adding a spacer 42 between the front conduit 2 and the front conduit C. When the stroke amount of the slide jack 41 is large, it is not necessary to transmit the propulsive force via the spacer 42.

According to the fifth embodiment, substantially the same effects as in the fourth embodiment can be obtained. In addition, even when the filler is injected into the distal end portion of the outer cylinder or the like, the excavation work can be performed by inserting the leading pipe C, and the laying work of the buried pipe can be restarted.

Next, a description will be given of a method of charging the leading conduit C according to the sixth embodiment. In the sixth embodiment,
Small-diameter thruster 1 used in first and second embodiments
The same one is used. FIG. 9 is an explanatory diagram for explaining a procedure of charging the leading conduit C of the sixth embodiment. The configuration common to the first and second embodiments will be described using the same reference numerals.

In the sixth embodiment, the outer diameter of the cutter head 6 is adjusted by extending the slide case sliding jack 23 and sliding the screw shaft 12 backward by moving the leading conduit C having the cutter head 6 on the front surface. In the reduced state, the cutter head 6 penetrates through the buried pipe 2 laid underground and the outer cylinder A until the front surface of the cutter head 6 comes into contact with the tunnel face at the same position as the tip surface of the outer cylinder A (FIG. ) (B)). When the filler is injected into the outer cylinder A, the leading pipe C is propelled while rotating the cutter head 6 to cause the outer cylinder A to rotate.
Dig to the same position as the tip surface of. The propulsion force is transmitted to the forward conduit C in the same manner as in the fifth embodiment.

Next, a driving force is transmitted to the leading conduit C to rotate the cutter head 6 and gradually contract the slide case sliding jack 23 to gradually reduce the outer diameter of the outer cylinder A. It is enlarged so as to approach the outer diameter (FIGS. 9C and 9D). When the cutter head 6 is excavated while the diameter thereof is expanded (FIG. 9E), the propulsion force transmitting members 30a and 30b of the leading conduit C reach the position facing the engaging groove 32 of the outer cylinder A. At this point, the jack 31 is extended, the propulsion force transmitting members 30a and 30b are engaged with the engagement grooves 32, and the leading pipe C and the outer cylinder A are integrated. After the leading pipe C and the outer tube A are integrated in this way, the rear end face of the buried pipe 2 is pressed by the propulsion device, and the propulsion work and the laying work of the buried pipe are performed again. Thus, the same effect as in the fifth embodiment can be obtained.

In the fourth, fifth and sixth embodiments, the same small-diameter thruster 1 as in the first and second embodiments is used.
However, even if the small-diameter thruster 1 'of the third embodiment is used, the front pipe C can be introduced into the underground buried pipe and the outer cylinder by the same procedure, and the same effect can be obtained. Can be obtained.

In each of the above-described embodiments, the screw conveyor 10 is used as the earth discharging device 9; however, the present invention is not limited to this, and a vacuum earth discharging device or a muddy water discharging device may be used. In such a case, the filler flow path piping may be provided inside the front conduit C or on the outer peripheral portion of the outer cylinder A, and each of the earth discharging devices may be used as the filler flow path pipe. When using the vacuum type earth removal device or the muddy water earth removal device, for example, a slide shaft (not shown) having a spherical tip is provided, and the distal end of the slide shaft is connected to the slide case 20. Thus, the slide case 20 needs to be slidable in the front-rear direction.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a front pipe of a small-diameter thruster according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line PP of FIG. 1;

FIG. 3 is an explanatory diagram for explaining a procedure for collecting a leading conduit according to the first embodiment.

FIG. 4 is an explanatory view (a) for explaining another method for propelling the outer cylinder forward, and an explanatory view (b) for explaining another method for propelling the front conduit forward.

FIG. 5 is an explanatory diagram for explaining a procedure for collecting a leading conduit according to a second embodiment.

FIG. 6 is an explanatory diagram for explaining a procedure for collecting a leading conduit according to a third embodiment.

FIG. 7 is an explanatory diagram for explaining a procedure for charging a front conduit according to a fourth embodiment.

FIG. 8 is an explanatory diagram for explaining a procedure for charging a front conduit according to a fifth embodiment.

FIG. 9 is an explanatory diagram for explaining a procedure for charging a front conduit according to a sixth embodiment.

FIG. 10 is a longitudinal sectional view of a leading pipe of a conventional small-diameter thruster.

FIG. 11 is a plan view of a leading pipe of a conventional small-diameter thruster.

FIG. 12 is a longitudinal sectional view of a leading conduit of a conventional small-diameter thruster.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Small-diameter propulsion machine 2 Buried pipe 3 Trunk part 3a Front trunk 3b Rear trunk 4 Swinging part 5 Disk cutter 6 Cutter head 6a Cutter head driving unit 7 Bulkhead 8 Chamber 9 Discharge device 10 Screw conveyor 11 Casing 12 Screw shaft 13 Drive motor 14 Support member 15 Bracket 16 Stopper 17 Gravel bite prevention rubber 19 Shaft 20 Slide case 21 Bracket 22 Link member 23 Slide case sliding jack 24 Drainage pipe 25 Switching valve 26 Suction side pipe 27 Delivery side pipe 30a, 30b Thrust transmission Member (connecting means) 31 jack 32 engaging groove 33 engaging member 35, 41 slide jack 36, 42 spacer 40 filler flow pipe A outer cylinder C tip conduit D expansion / contraction mechanism (expansion / contraction means)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsuneo Sugiraira 5 Yokaichi Town, Komatsu City, Ishikawa Prefecture Inside the Komatsu Plant, Ltd. (72) Inventor Hiroshi Akiyama 5 Yokaichi Town, Komatsu City, Ishikawa Prefecture 5 Komatsu Manufacturing Co., Ltd. Inside the Komatsu Plant (72) Inventor Matsuyuki Fujii 2-3-6 Akasaka, Minato-ku, Tokyo Komatsu Seisakusho Headquarters (72) Inventor Shouichi Abo 2-3-6-6 Akasaka, Minato-ku, Tokyo Komatsu Seisakusho In-house (72) Inventor Sadamasa Kodaira 5 Yokaichi-cho, Komatsu-shi, Ishikawa Pref. Komatsu, Ltd. Komatsu Plant F-term (reference) 2D054 AC18 AD32 BA03 DA03 DA13

Claims (6)

[Claims] 1. An outer cylinder connected to a tip of a buried pipe and having an outer diameter substantially the same as the outer diameter of the buried pipe, and a rear end to be inserted into the outer cylinder when the buried pipe is laid. A small-diameter thruster having a conduit, (a) a cutter head rotatably provided at a front portion of the leading conduit, the cutter head being capable of expanding and contracting an outer diameter thereof, and (b) the laying of the buried pipe when laying the buried pipe. The outer diameter of the cutter head is enlarged so as to be substantially the same as the outer diameter of the buried pipe, and the outer diameter of the cutter head is made smaller than the inner diameter of the buried pipe when passing the leading conduit through the outer cylinder and the buried pipe. And (c) connecting the leading pipe and the outer cylinder when laying the buried pipe, and connecting the leading pipe in the outer cylinder and the buried pipe when connecting the leading pipe. Connection means for releasing and separating the leading conduit and the outer cylinder is provided. Small caliber thruster. 2. An outer cylinder connected to a tip of a buried pipe and having an outer diameter substantially the same as the outer diameter of the buried pipe. The front pipe is recovered through a buried pipe laid using a small-diameter thruster having a front pipe provided with a scalable cutter head having an outer diameter smaller than the inner diameter of the buried pipe at a front end so as to be connectable and separable. In the method of collecting a front pipe, the cutter head is reduced in diameter, and after the connection between the front pipe and the outer pipe is released, the outer pipe and the embedded pipe are inserted until the front end of the outer pipe reaches the substantially front end position of the cutter head. A method for recovering a front conduit, comprising pushing in a pipe and then applying a retraction force to the front conduit to recover the front conduit through the outer cylinder and the buried pipe. 3. An outer cylinder connected to the tip of a buried pipe and having an outer diameter substantially the same as the outer diameter of the buried pipe. The front pipe is recovered through a buried pipe laid using a small-diameter thruster having a front pipe provided with a scalable cutter head having an outer diameter smaller than the inner diameter of the buried pipe at a front end so as to be connectable and separable. In the method of recovering the leading conduit, the cutter head is reduced in diameter, and after disconnecting the leading conduit and the outer cylinder, a pull-back force is applied to the leading conduit while injecting a chemical solution in front of the leading conduit. A protective wall by retracting the protective pipe by a predetermined amount, and then recovering the leading pipe through the outer cylinder and the buried pipe. 4. An outer cylinder connected to the tip of a buried pipe and having an outer diameter substantially the same as the outer diameter of the buried pipe. The front pipe is recovered through a buried pipe laid using a small-diameter thruster having a front pipe provided with a scalable cutter head having an outer diameter smaller than the inner diameter of the buried pipe at a front end so as to be connectable and separable. In the method for collecting a leading pipe, the cutter head is reduced in diameter, and after the leading pipe is disconnected from the outer pipe, the outer pipe and the buried pipe are moved until the tip of the outer pipe reaches the tip position of the cutter head. After that, a protective wall is formed by applying a retraction force to the front conduit while injecting a chemical solution in front of the front conduit and retracting it by a predetermined amount, and then collecting the front conduit through the outer cylinder and the buried pipe. And the destination conduit Osamu way. 5. A buried pipe laid in the ground and an outer cylinder connected to a tip of the buried pipe, the outer diameter of which is substantially the same as the outer diameter of the buried pipe when the diameter is increased, and the buried pipe which is smaller when the diameter is reduced. A method of providing a front conduit having an expandable / contractible cutter head having an outer diameter smaller than the inner diameter at the front end portion and supplying a front conduit capable of being connected to and separated from the outer cylinder, wherein the cutter head includes a front conduit whose diameter is reduced. After being inserted so as to pass through the buried pipe, a retraction force is applied to the buried pipe to pull back the outer cylinder to a connection position with the front pipe, connect the front pipe with the outer pipe, and cut the cutter. A method for inserting a leading conduit, wherein the diameter of the head is increased. 6. The inside of a buried pipe laid underground and an outer cylinder connected to the tip of the buried pipe have an outer diameter substantially the same as the outer diameter of the buried pipe when the diameter is expanded, and the buried pipe when the diameter is reduced. A method of providing a front conduit having an expandable / contractible cutter head having an outer diameter smaller than the inner diameter at the front end portion and supplying a front conduit capable of being connected to and separated from the outer cylinder, wherein the cutter head includes a front conduit whose diameter is reduced. After being inserted so as to pass through the buried pipe, the diameter of the cutter head is expanded, or the diameter of the cutter head is expanded while being excavated, and then the front pipe is excavated to a connection position with an outer cylinder, and the front pipe is excavated. And connecting the outer tube to the outer tube.