JPH108887A - Tunnel boring machine and boring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily inspect and change a cutter bit by mounting a cutter head having many cutter bits so as to be capable of being housing in a rotation body, and rotating the rotation body around a rotational axis orthogonal with the excavating direction. SOLUTION: A hollow and polyhedral rotation body 15 is held in the front barrel 11 of an excavator body along a rotation axis O orthogonal with the excavating direction, so as to be capable of freely turning. In addition, a cylindrical travel body 22 is provided within the rotation body 15, so as to be capable of moving in the excavating direction, and a freely rotatable cylinder 24 is mounted on the front of the travel body 22. In this case, a disc type cutter head 25 is fixed to the cylinder 24 and a cutter bit 26 is fitted to the cutter head 25. Also, the rotation body 15 houses the cutter head 25 and an expansion cutter 29. Then, the rotation body 15 is horizontally turned around the rotation axis O and the cutter head 25 is directed toward a position aft of the excavating direction within the front barrel 11, thereby inspecting the abrasion status of the cutter bits 26, 27 and 30, and implementing the change thereof whenever necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tunnel excavator and a tunnel excavation method, and more particularly, to an operation for exchanging a cutter bit mounted on a cutter head of a tunnel excavator.

[0002]

2. Description of the Related Art In a shield excavator for excavating ground, a cutter head which is rotatable and rotatable is mounted on a front part of a cylindrical excavator body, and a plurality of shield heads are circumferentially mounted on a rear part. The jacks are arranged side by side, and the segment elector device is mounted. When excavating and forming a tunnel using this shield excavator, excavating the ground in front by rotating the cutter head, extending the shield jack and advancing the excavator body by the reaction force against the existing segment I do. Then, the excavated earth and sand are discharged to the outside, and the segments are assembled to the tunnel wall surface by the segment elector device to construct a tunnel of a predetermined length.

[0003] In recent years, tunnels formed by excavation have tended to be long-distance, and a cutter bit mounted on a cutter head may be worn out during excavation work by a shield excavator. If the cutter bit is worn, the excavation efficiency of the bedrock is reduced, so the excavation operation must be stopped and the worn cutter bit must be replaced. In the above-mentioned conventional shield excavator, first, the ground in front of the shield excavator for which the cutter bit is to be replaced is solidified and improved by injection of chemicals or freezing, and the tunnel excavator is excavated to this ground improvement point. Let it. Here, the shield excavator is stopped to discharge all excavated earth and sand in the chamber, and the worker enters the chamber to replace the cutter bit,
That is, the worn cutter bit is removed and a new cutter bit is mounted.

However, the work of replacing the cutter bit in this shield excavator is costly and uneconomical due to the use of chemicals and the like used for improving the ground, and requires a long working time. Not good. In addition, since the worker works in a narrow space in the chamber, there is a problem that the work is inconvenient and the burden on the worker increases. Therefore, a cutter head is moved into the body of the excavator so that the cutter bit can be replaced in the body of the excavator, for example, as disclosed in Japanese Patent Application Laid-Open No. H4-224392.

In the shielded excavator disclosed in Japanese Patent Application Laid-Open No. 4-24392, a spherical working chamber is rotatably supported with a horizontal axis in a cylinder, and an excavator is provided in the spherical working chamber. The cutter of this excavator protrudes in front of and is rotatably provided. Therefore, when performing inspection work or replacement work of the cutter bit, the cutter is housed in the spherical working chamber, and then the spherical working chamber is raised by applying a rotational force from the outside to the spherical working chamber with a jack. To rotate. Then, when the spherical work chamber is rotated by approximately 180 degrees and the cutter is positioned in the cylinder, the rotation of the spherical work chamber is stopped, and the cutter bit is replaced in this state.

[0006]

However, in the shielded excavator disclosed in this publication, when inspecting or exchanging the cutter bit, the cutter and the excavator are stored in a spherical working chamber and the spherical excavator is closed. By rotating the working chamber, the cutter is positioned inside the cylinder. In this case, the spherical working chamber is rotated by connecting the inside of the cylindrical body and the spherical working chamber by a jack and driving the jack to expand and contract to apply a rotational force to the spherical working chamber from the outside. However, in order to move the cutter located outside to the inside of the cylinder, it is necessary to rotate the spherical working chamber by approximately 180 degrees, which is not possible with a single reciprocating drive of the jack. Therefore, every time the spherical work chamber is rotated by a predetermined angle by the reciprocating drive of the jack, the connection position between the jack and the spherical work chamber must be changed, and this work must be repeated several times, and the work is troublesome. A long time is required for the work, and the burden on the worker is large, and there are problems in work efficiency and safety.

A jack for rotating the spherical working chamber is disposed behind the spherical working chamber, and it is necessary to provide an operating space for the jack in this portion, and a connection position between the jack and the spherical working chamber. It is necessary to secure a work space for the change work, and there is a problem that the machine length of the cylindrical body is increased and the size of the apparatus is increased.

The present invention is intended to solve such a problem, and the work of replacing the cutter bit is performed easily and in a short time, thereby reducing the burden on the operator and improving the safety. An object of the present invention is to provide a tunnel excavator and an excavation method that improve the efficiency of exchange work.

[0009]

According to a first aspect of the present invention, there is provided a tunnel excavator, comprising: a tubular excavator body;
Propulsion means for advancing the excavator body, and a plurality of pressing portions rotatably mounted in the excavator body with a rotation axis substantially orthogonal to the excavation direction and arranged in parallel along the rotation direction. A rotating body having a hollow body, a plurality of rotating body driving units mounted on the excavator body, and sequentially rotating the rotating body by a predetermined angle by sequentially pressing the plurality of pressing portions; and a rotatable rotating body. A cutter head mounted on the excavator main body and capable of protruding forward of the excavator body and capable of being housed in the rotating body; a number of cutter bits mounted on a front portion of the cutter head; and driving and rotating the cutter head. And a cutter head driving means.

Therefore, in a state where the cutter head protrudes from the rotating body toward the front of the excavator body, the propulsion means advances the tubular excavator body while driving and rotating the cutter head by the cutter head driving means. The front ground is excavated by a number of cutter bits mounted on the front portion of the cutter head to form a tunnel. And
When excavation work is performed for a long period of time, it is necessary to inspect the wear state of the cutter bit.In this case, the drive rotation of the cutter head is stopped, and this cutter head is stored in the rotating body, and then rotated by the rotating body driving means. By sequentially pressing a plurality of pressing portions of the body and rotating this rotating body at a predetermined angle with a rotation axis substantially orthogonal to the excavation direction,
The cutter head is positioned in the body of the excavator, and in this state, the state of wear of the cutter bit is inspected, and if replacement is necessary, an operator replaces the cutter bit using a predetermined replacement jig.

In the tunnel excavator of the present invention,
The hollow rotary body has a cylindrical portion and front and rear spherical portions, and a pair of shaft portions provided on an outer peripheral portion of the cylindrical portion are rotatably supported in the excavator body via bearing means. The plurality of pressing portions are formed on the outer peripheral surface of the cylindrical portion, and a driving jack as the rotating body driving means is provided between the excavator body and the cylindrical portion. It is a feature.

Therefore, the rotating body can be rotated with high precision because the shaft provided on the outer periphery of the cylindrical portion is rotatably supported in the excavator body. Since the pressing portion and the drive jack are disposed between the excavator body and the tubular portion, the excavator body does not increase in size.

In the tunnel excavation method of the present invention, the cutter head mounted on the front part of the cylindrical excavator body is driven and rotated while the excavator body is advanced, so that the cutter head is mounted on the front part of the cutter head. In a tunnel excavation method in which a large number of cutter bits crush the ground in front to excavate a tunnel, during tunnel excavation, the cutter head is stopped in the hollow rotary body after stopping the driving rotation of the cutter head, The plurality of rotating body drive jacks provided on the excavator body are sequentially expanded and contracted to sequentially press a plurality of pressing portions arranged side by side along the rotating direction of the rotating body, so that the rotating body is moved in the excavation direction. The cutter head is moved into the body of the excavator by a predetermined angle with a rotation axis substantially perpendicular to the cutter head, and the cutter bit attached to the cutter head in this state is rotated. It is characterized in carrying out the inspection or replacement of worn cutter bit wear condition.

Therefore, when inspecting the worn state of the cutter bit attached to the cutter head or replacing the worn cutter bit, the driving rotation of the cutter head is stopped, and the cutter head is housed in a hollow rotating body. The rotary body drive jack is sequentially expanded and contracted to sequentially press a plurality of pressing portions of the rotary body, thereby rotating the rotary body by a predetermined angle, moving the cutter head into the excavator body, and performing various operations. As a result, each task becomes easier, the burden on the worker is reduced, and safety is improved.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic vertical section of a shield excavator according to an embodiment of the present invention, FIG. 2 is a schematic cross section of the shield excavator, FIG. 3 is a cross section showing a support structure of a rotating body, and FIG. 5 to 7 schematically illustrate a rotation operation of the rotating body, and FIG. 8 illustrates a bottom view schematically illustrating the operation of the rotating mechanism of the rotating body. An outline is shown.

In the shield excavator of the present embodiment, FIG.
As shown in FIG. 2 and FIG. 2, the excavator body has a front body 11 and a rear body 12 each having a cylindrical shape, which are swingably connected via a spherical bearing 13 between the front body 11 and the rear body 12. Is provided with a folding jack 14. In the front body 11, a rotating body 15 forming a hollow polyhedron with a rotation axis O substantially orthogonal to the excavation direction is rotatably supported. The rotating body 15 includes an outer cylindrical portion 15a and an inner cylindrical portion 15b, a front spherical portion 15c and a rear spherical portion 15d integrally formed before and after the cylindrical portions 15a and 15b,
It comprises upper and lower bearing mounting portions 15e attached to the outer cylindrical portion 15a and the inner cylindrical portion 15b. As shown in FIGS. 1 and 3, the rotating body 15 includes a pair of upper and lower rotating shafts 1 fixed to the upper and lower inner peripheral surfaces of the front body 11.
Each of the bearings 6 is provided with a bearing mounting portion 15 e via a bearing 17, so that the front body 11 is rotatable about a vertical rotation axis O in the front body 11. As shown in FIGS. 1 and 2, the rotating body 15 includes a front end spherical portion 15 c and a rear end spherical portion 1.
5d is supported by seal members 20, 21 attached to support frames 18, 19 at the front and rear of the front body 11, respectively.

A cylindrical moving body 22 is movably fitted on the inner peripheral surface of the inner cylindrical portion 15b of the rotating body 15 configured as described above along the digging direction. Can be moved back and forth by a plurality of slide jacks 23 arranged in the rotating body 15. A cylindrical body 24 is rotatably attached to the front of the moving body 22. A disk-shaped cutter head 25 is fixed to the cylindrical body 24. A bit 26 is mounted, and a number of fixed cutter bits 27 are fixed around the bit 26. The cutter head 25 is provided with a telescopic cutter 29 which can be retracted outward by a hydraulic jack 28, and a number of fixed cutter bits 30 are also fixed to the telescopic cutter 29. Then, a cylindrical body 24 integrated with the cutter head 25 is formed.
A ring gear 31 is fixed to a rear portion of the motor, and a driving gear 33 of a cutter driving motor 32 mounted on the moving body 22 meshes with the ring gear 31. On the other hand, the rotating body 15 is provided with an opening / closing door 34 at the rear end portion of the rear end spherical portion 15 d through which an operator enters and exits the inside of the rotating body 15. An opening / closing door 35 is provided to enter and exit from the front side of the front trunk 11 from the side 12.

Accordingly, when the movable body 22 moves forward by extending the slide jack 23, and when the telescopic cutter 29 projects outward by extending the hydraulic jack 28, the cutter head 2
5 is located in front of the front trunk 11, and the tip of the telescopic cutter 29 is located on the outer periphery of the front trunk 11. In this state,
When the drive motor 32 is driven, the cylindrical body 24 rotates via the drive gear 33 and the ring gear 31, and the cylindrical body 24
By rotating the cutter head 25 integral with the front cutter 11, the preceding ground can be excavated by the leading cutter bit 26 and the fixed cutter bits 27 and 30, and a tunnel having substantially the same diameter as the front trunk 11 can be excavated.

As described above, the rotating body 15 is rotatably supported in the front body 11, and has a horizontal axis O with the cutter head 25 and the telescopic cutter 29 housed therein. Can rotate. As shown in FIGS. 3 and 4, a plurality of fixing pins 36a, 36b, 36c, 36d, 36e... Are provided on the lower surface (or upper surface) of the rotating body 15 at the same radial position from the rotation axis O.
Are fixed at a pitch of a predetermined angle θ (for example, 20 degrees). On the other hand, four rotating jacks 37, 38, 39, and 40 are provided at the lower portion (or upper surface portion) of the front trunk 11.
Are provided side by side, and the rotary jacks 37 and 38 are
5 is rotated to the right.
Is for rotating the rotating body 15 counterclockwise, but the rotary jacks 37, 38, 39, and 40 have substantially the same structure.

That is, each of the rotary jacks 37, 38, 3
9 and 40 are drive rods 37a and 38 which can be moved in and out, respectively.
a, 39a, and 40a are connected to a reaction member 19a integrally formed with the support frame 19 of the front body 11, and guides 37c, to which the jack bodies 37b, 38b, 39b, and 40b are fixed to the front body 11, 38c, 39c, and 40c are slidably supported. And the rotating jacks 37, 3
When 8, 39, and 40 are extended by one stroke, the pressing portions 37d, 37d, of the jack bodies 37b, 38b, 39b, 40b,
Fixing pins 36a, 3 corresponding to 38d, 39d, 40d
6b, 36c, 36d, 36e,..., The rotating body 15 is rotated at an angle of θ / 2 (for example, 10
(Degree).

As shown in FIG. 1 and FIG.
A plurality of shield jacks 41 are arranged side by side in the circumferential direction, and a segment erector device 42 is provided in 2. By pushing the shield jack 41 against the existing segment S assembled on the inner peripheral surface of the excavated tunnel by the extension driving, the front trunk 11 and the rear trunk 12 can be advanced by the reaction force. In addition, the segment erector device 42 is movable in the circumferential direction and the radial direction of the existing tunnel, grasps the segment S carried into the existing tunnel, moves to a predetermined position, and moves the front trunk 11 and the existing segment S together. A tunnel can be constructed by mounting the segment S in a space between the two. Note that a chamber chamber 43 is formed in the front body 11 between the cutter head 25 and the rotating body 15, and one end is extended to a muddy water treatment (not shown) and disposed so as to pass through the inside of the front body 11. Water pipe 44
The other end of the sludge pipe 45 is open to the chamber 43.

In order to excavate and form a tunnel with the above-described shield excavator according to the present embodiment, FIGS.
As shown in FIG. 3, the slide jack 23 is extended to move the moving body 22 forward, and the hydraulic jack 28 is extended to project the telescopic cutter 29 outward, so that the cutter head 25 is moved forward of the front body 11. Position. In this state, first, the plurality of shield jacks 41 are extended while rotating the cutter head 25 by the drive motor 32, and the front body 11 and the rear body 12 constituting the excavator body are formed by the reaction force against the existing segment S. To move forward. Then, the ground ahead is crushed by the leading cutter bit 26 and the fixed cutter bits 27 and 30, and a tunnel is excavated. The earth and sand excavated by the cutter bits 26, 27, 30 is taken into the chamber 43, and is discharged to the outside through the drain pipe 45 together with the water supplied from the water pipe 44. Next, one of the shield jacks 41 is operated in the contracting direction to form a space between the shield segment 41 and the existing segment S, and a new segment S is mounted in the space by the segment elector device 42. By repeating this operation, a tunnel of a predetermined length is excavated and formed.

When the excavation work by such a shield excavator is continued for a long time, the cutter bits 26, 27, 30
Is worn out, it is necessary to inspect the state of wear.
In this case, first, the cutter head 2
5 and the driving of the shield jack 41 is stopped, and the operator opens the opening / closing doors 34 and 35 to enter the working chamber in the rotating body 15 where the wiring of the electric system such as the driving motor 32 and the like are removed. Separate hydraulic system wiring and water pipe 4
After performing the work of disconnecting the pipes from the drain pipe 4 and the exhaust pipe 45, the doors 34 and 35 are closed. And as shown in FIG.
By contracting the hydraulic jack 28, the telescopic cutter 29 is moved inward and housed in the cutter head 25, and then by contracting the slide jack 23, the moving body 22 is retracted, and the cutter head 25 and the telescopic cutter 29 are retracted. The rotating body 1
5. Next, each rotating jack 3
The rotary body 15 is rotated by a predetermined angle by sequentially extending and retracting the cutters 7 and 38, and the cutter head 25 is directed rearward in the excavation direction in the front body 11, and the wear state of the cutter bits 26, 27 and 30 is inspected or replaced. I do.

That is, as shown in FIG. 8A, when the rotary jack 37 is operated to extend the drive rod 37a, the jack body 37b moves along the guide 37c, and the pressing portion 37d is fixed to the fixing pin 37d. 36a. Then, as shown in FIG. 6B, when the rotary jack 37 is extended by a full stroke, the pressing portion 37d presses the fixing pin 36a, so that the rotating body 15 is rotated by an angle of θ / 2.
Next, as shown in FIG.
The 7th drive rod 37a is contracted and returned to the original position. On the other hand, the rotation jack 38 is operated to extend the drive rod 38a, and the pressing portion 38d presses the fixing pin 36b, thereby rotating the rotating body 15 by an angle of θ / 2. At this point, the rotating body 15 is moved by the angle θ, that is, the fixed pins 36a and 36
It rotates by the interval of b, and by repeatedly performing this operation, the rotating body 15 rotates as shown in FIG.

When the rotating body 15 is rotated by a predetermined angle α (for example, 120 degrees) as shown in FIG. 7, the cutter head 25 in the rotating body 15 faces rearward in the digging direction and the front body. Since there are sealing members 20 and 21 between the rotating body 15 and the front body 11, excavated earth and sand and muddy water do not enter the rotating body 15. In this state, the operator operates the cutter bit 26 attached to the cutter head 25,
Inspection of the wear conditions of 27 and 30 is carried out. If the progress of wear is severe, the work of replacing the cutter bit is carried out using a replacement jig (not shown).

After that, when the inspection work and the replacement work of the cutter bit are completed, the rotating body 15 is rotated by a predetermined angle α in a direction opposite to the above by using the rotating jacks 39 and 40.
Return to the original position. Then, the movable body 22 is advanced by extending the slide jack 23, the cutter head 25 and the telescopic cutter 29 are projected forward from the rotating body 15, and then the hydraulic jack 28 is extended to extend the telescopic cutter 29.
Is moved outward, and as shown in FIG. 1 and FIG. Then, as described above, the cutter head 2
5 is driven to rotate to excavate the ground in front to form a tunnel.

[0028]

As described above in detail with reference to the embodiments, according to the tunnel excavator of the present invention, the excavator main body which can be propelled is rotatable with the rotation axis substantially orthogonal to the excavation direction. Along with mounting a hollow rotating body having a plurality of pressing portions arranged in parallel along the rotation direction,
The rotating body is rotatable by a predetermined angle by sequentially pressing the plurality of pressing portions by a plurality of rotating body driving means, and is a drive rotatable cutter head that can protrude forward of the excavator body and can be housed therein. Is mounted on the rotating body, and a number of cutter bits are mounted on the front surface of the cutter head.After storing the cutter head in the rotating body, the rotating body driving means sequentially presses a plurality of pressing portions of the rotating body. By rotating the lever body by a predetermined angle, the cutter head can be positioned in the excavator body, and in this state, the wear state of the cutter bit can be easily inspected, and if it is necessary to replace the cutter bit, The cutter bit can be replaced using a predetermined replacement jig, and the work of replacing the cutter bit can be performed easily and in a short time to reduce the burden on an operator and improve safety. In, it is possible to improve the work efficiency of the replacement work.

According to the tunnel excavator of the present invention,
The hollow rotating body has a cylindrical portion and front and rear spherical portions, and rotatably supports a pair of shaft portions provided on the outer peripheral portion of the cylindrical portion in the excavator body via bearing means, Since the plurality of pressing portions are formed on the outer peripheral surface of the cylindrical portion, and a driving jack as a rotating body driving means is disposed between the excavator body and the cylindrical portion, the rotating body is formed on the outer periphery of the cylindrical portion. The rotating body can be rotated with high precision because the shaft portion provided in the portion is rotatably supported in the excavator body, and the pressing portion and the driving jack are connected to the excavator body and the cylindrical portion. And the size of the excavator body can be reduced.

Further, according to the tunnel excavation method of the present invention, during the excavation of the tunnel, after the driving rotation of the cutter head is stopped, the cutter head is housed in the hollow rotating body, and the plurality of rotating heads provided on the excavator body are provided. The body drive jack is sequentially expanded and contracted to sequentially press a plurality of pressing portions arranged side by side along the rotating direction of the rotating body, thereby rotating the rotating body at a predetermined angle with a rotation axis substantially orthogonal to the excavation direction. By rotating the cutter head into the body of the excavator, and in this state, inspecting the worn state of the cutter bit attached to the cutter head or replacing the worn cutter bit, the inspection and inspection of the cutter bit were performed. By performing the replacement work easily and in a short time, the burden on the worker can be reduced, safety can be improved, and work efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a shield excavator according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a shield excavator.

FIG. 3 is a cross-sectional view illustrating a support structure of a rotating body.

FIG. 4 is a schematic bottom view showing a rotating mechanism of a rotating body.

FIG. 5 is a schematic top view for explaining the rotation operation of the rotating body.

FIG. 6 is a schematic top view for explaining the rotation operation of the rotating body.

FIG. 7 is a schematic top view for explaining the rotation operation of the rotating body.

FIG. 8 is a schematic bottom view for explaining the operation of the rotating mechanism of the rotating body.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Front trunk (excavator main body) 12 Rear trunk (excavator main body) 15 Rotating body 15a, 15b Cylindrical part (cylindrical part) 15c, 15d Spherical part 15e Bearing mounting part 16 Rotating shaft 17 Bearing 20, 21 Seal member 22 Moving body 23 Slide jack 25 Cutter head 27, 30 Fixed cutter bit 29 Telescopic cutter 32 Cutter drive motor (cutter head drive means) 36a, 36b, 36c ... Fixed pin (pressing portion) 37, 38, 39, 40 Rotation Jack (rotating body driving means) 41 Shield jack (propulsion means) O Rotation axis

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshihiko Bessho 1-25-1, Nishishinjuku, Shinjuku-ku, Tokyo Taisei Construction Co., Ltd. (72) Inventor Kenichi Kaneko 1-25-1, Nishishinjuku, Shinjuku-ku, Tokyo Taisei Corporation

Claims (3)

[Claims] 1. An excavator body having a cylindrical shape, a propulsion means for advancing the excavator body, and mounted rotatably in the excavator body with a rotation axis substantially orthogonal to a digging direction. A hollow rotating body having a plurality of pressing portions arranged side by side along a rotation direction, and a plurality of rotating members mounted on the excavator body and rotating the rotating body by a predetermined angle by sequentially pressing the plurality of pressing portions. Rotating body driving means, a cutter head rotatably mounted on the rotating body and capable of protruding forward of the excavator body and being housed in the rotating body,
A tunnel excavator comprising: a plurality of cutter bits mounted on a front portion of the cutter head; and cutter head driving means for driving and rotating the cutter head. 2. The tunnel excavator according to claim 1, wherein said hollow rotary body has a cylindrical portion and front and rear spherical portions, and a pair of shaft portions provided on an outer peripheral portion of said cylindrical portion are bearings. The excavator body is rotatably supported in the excavator body via a unit, the plurality of pressing portions are formed on an outer peripheral surface of the cylindrical portion, and a driving jack as the rotating body driving means is connected to the excavator body. And a tubular excavator disposed between the tubular portion and the tubular portion. 3. A plurality of cutter bits mounted on a front portion of the cutter head are moved forward by driving the cutter head mounted on the front portion of the cylindrical excavator body while driving and rotating the cutter head. In the tunnel excavation method of crushing the ground and excavating a tunnel, during the tunnel excavation, the cutter head is stopped in the hollow rotary body after the driving rotation of the cutter head is stopped, and the cutter head is provided in the excavator body. By sequentially expanding and contracting a plurality of rotating body driving jacks and sequentially pressing a plurality of pressing portions arranged side by side along the rotating direction of the rotating body, the rotating body is substantially perpendicular to the excavation direction. The cutter head is moved into the excavator body by a predetermined angle, and in this state, the cutter bit mounted on the cutter head is inspected for wear or worn. A tunnel excavation method, wherein a cutter bit is replaced.