JP2001140585A - Free cross sectional shield machine and widening shield tunneling method using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expand or shrink an excavation cross sectional shape in width and increase the degree of freedom of the excavation cross sectional shape. SOLUTION: A rotor 2 is provided in the front of a skin plate 1 capable of being expanded or shrunk in width as a shield machine main body. The rotor 2 is provided with a main cutter 3 and planetary cutters 7 revolved around the axis of the main cutter 3 with the rotation of the main cutter 3 and capable of being displaced in the radial direction of the rotor 2. A control means controlling the revolution locus of the planetary cutters 7 is provided, and the planetary cutter target locus of the control means can be adjusted according to the expanded/shrunk width of the skin plate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield machine having a free section in which the width of a shield machine body can be enlarged and reduced, and a widening shield method using the same.

[0002]

2. Description of the Related Art Conventionally, a shield method using a shield machine is well known as an effective means for excavating a tunnel. According to this method, a tunnel having a uniform shape corresponding to the excavation shape by the cutter of the shield machine and the cross-sectional shape of the shield machine body is excavated.

However, in a road tunnel, it is necessary to change the width and height of the tunnel halfway for the purpose of enlarging the field of view at a curved portion, setting up an emergency stop zone, and the like. Also, when excavating a tunnel while curving it with a relatively large curvature, there is also a demand for securing an extra excavation amount so that the shielding machine body of the shielding machine does not compact with the earth and sand at the curved portion.

Accordingly, in recent years, a shield machine capable of changing the cross section of the excavation has been developed. Specifically, the following is known.

A) Japanese Patent Application Laid-Open No. 8-93381: A cylindrical outer shell plate (shielding machine main body) is divided in the circumferential direction so that the whole can be expanded in diameter. The disk-shaped cutter head at the front of the shield machine is provided with an over-cutter that can protrude radially outward on the outer periphery thereof, so that the ground around the excavator can be widened by the amount of protrusion of the over-cutter.

B) JP-A-6-146775: a shield frame (shield machine body) is divided into a central body and lateral bodies on both outer sides thereof, and the lateral bodies slide with respect to the central body. The entire width of the shield frame is scaled. Furthermore, a main cutter is arranged in front of the central body, and a sub-cutter is arranged in front of both side bodies, and these cutters are arranged side by side in a state of being partially overlapped.
A so-called multiple structure is adopted, and the sub cutter corresponding to the side body slides along with the slide of the side body.

[0007]

In the shielding machine of A), since the overcut is only performed by the overcutter protruding radially outward from the cutter head, the shape of the excavated cross section can be changed even if it can be changed. It is always circular and can only adjust the radius of its circular cross section. As described above, since the overcut amount is always set over the entire circumference of the tunnel, for example, the shape of the tunnel is partially expanded to the side for the purpose of securing a surplus digging amount in a curve excavation or setting up an emergency stop zone. Is impossible, and the degree of freedom in shape setting is extremely low. Therefore, its use is limited to a very narrow range.

In the shield machine of B), since the excavated cross-sectional shapes of the cutters arranged in the horizontal direction are all circular, the cross-sectional shapes of the shield frame main body and the both side portions which take in the sediment following the cuts are also the same. It must be circular or nearly circular, corresponding to the cutter excavation shape. Therefore, the cross-sectional shape of the entire shield frame is a complex shape obtained by combining a plurality of circles. Regardless of the expansion width, since the size relationship between the excavation area of each cutter and the opening area where the shield frame takes in earth and sand is always constant, the amount of extra digging (the amount of overcut outside the cross section of the shield frame) must be reduced. Cannot be set freely.

In view of such circumstances, the present invention provides a shield machine capable of setting the excavated cross-sectional shape with a high degree of freedom while enabling a good extensible cross-sectional shape, and a widened shield using the same. The purpose is to provide a construction method.

[0010]

As a means for solving the above-mentioned problems, the present invention is directed to a shield machine main body which is expandable and contractible, and is supported by the shield machine main body so as to be rotatable around an axis extending in the propulsion direction. Rotating body, a main cutter that rotates integrally with the rotating body and excavates a central portion of an excavation section, a rotating body driving unit that drives the rotating body, and is supported by the rotating body so as to be displaceable in a radial direction thereof. A planetary cutter for excavating a portion of the excavated cross section that is not excavated by the main cutter by revolving with the rotation of the rotating body; and control means for controlling a revolving locus of the planetary cutter. A free-section shield machine configured such that the revolution trajectory of the planetary cutter to be adjusted can be adjusted in accordance with the expansion / contraction width of the shield machine body (claim 1).

In this shield machine, the combination of the main cutter and the planetary cutter is used as the excavating means. Therefore, even if the shield machine body is expanded or contracted, only the orbit of the planetary cutter is changed in accordance with this. The excavation shape can flexibly correspond to the shape of the shield machine body. Therefore, the excavation shape can be easily enlarged and reduced in width, and the shape of the shield machine main body and the form of the expansion and contraction width are less restricted, and the excavation shape can be set with a high degree of freedom.

The control means includes a planetary cutter operating means for displacing each of the planetary cutters in the radial direction of the rotating body, and a revolving locus of each of the planetary cutters associated with the rotation of the rotating body coincides with a set target locus. Planetary cutter operation control means for controlling the operation of the planetary cutter operation means during rotation of the rotating body, and the target trajectory of the planetary cutter operation control means is adjusted according to the expansion / contraction width of the shield machine body. It is preferable that the configuration is such that it is possible (claim 2). With this configuration, it is possible to easily cope with the enlargement / reduction width of the shield machine main body only by changing the target trajectory of the planetary cutter operation control means.

The control target trajectory of the planetary cutter operation control means may be set in an analog manner, but a plurality of control modes having different target trajectories are prepared in advance, and these control modes are set. If a control mode storage means for storing the control mode is provided, and the operation of the planetary cutter operating means is controlled based on a control mode selected from these control modes (Claim 3), the operator can control the control mode. Among them, the enlargement / reduction work can be performed by a simple operation simply by adopting a control mode suitable for the actual width of the shield machine body. Moreover, the program required for the control is greatly simplified.

For example, the shape of the front end of the shield machine body is divided into a plurality of stages from the minimum width shape to the maximum width shape, and the target trajectory in each of the control modes is adjusted according to the shield machine body front end shape at each stage. If the shape is set (claim 4), widening excavation can be dealt with simply by switching the current control mode to a control mode having a larger target trajectory.

Further, the control mode may include a control mode having a target trajectory corresponding to a front end shape of the shield machine main body when the shield machine main body is widened to only one side (claim 5).

[0016] The control means may be such that guide means for guiding the planetary cutters is provided on the main body of the shield machine so that each of the planetary cutters draws a predetermined orbit along with the rotation of the rotating body. . In this case, the guide shape of the planetary cutter by the guide means may be configured to change in accordance with the width of expansion and contraction of the shield machine body.

Specifically, a guide rail is provided on the inner surface of the shield machine main body so as to expand and contract with the shield machine main body, and the planetary cutter or the planetary cutter is integrally formed during rotation of the rotating body. It is preferable that the apparatus has a pressing means for pressing the displaceable member against the guide rail (claim 7).

In the shield machine according to the present invention, the shield machine is provided with expanding / contracting width means for enlarging / reducing the width of the shield machine main body, and the enlarging / contracting width means is provided so that the front end width of the shield machine main body is larger than the rear end width. It is more preferable that the taper shape is adopted so that the width can be enlarged and reduced (claim 8). By adopting such a tapered shape as the shield machine main body shape, it is possible to secure a large sediment intake at the front of the shield machine main body while avoiding consolidation between the rear part of the shield machine body and the ground, and to excavate well. Can be performed.

More specifically, a plurality of expanding / contracting width means are arranged side by side in the front-rear direction of the shield machine main body, and the width of the shield machine main body by each expanding / contracting width means can be set independently in front and rear. The one configured is preferable (claim 9). In this configuration, the shield machine body shape can be tapered as described above by making the shield machine body width by the front-side enlargement / reduction width means larger than the shield machine body width by the rear-side enlargement / reduction width means. The degree of taper can be freely adjusted according to the excavation state.

The shield machine according to the present invention not only constructs a tunnel having the same shape as the excavated cross section, but also constructs a tunnel having a cross section larger than the excavated cross section by connecting a plurality of the excavated cross sections. It is also possible. However, when the excavated cross-sectional shape and the shield machine main body shape are substantially equivalent to the segment assembled shape, the excavated cross-sections cannot be overlapped with each other. It will take time to improve.

On the other hand, if a part of the shield machine body is made to protrude outside the segment assembly shape, and the protruding portion is provided with an auxiliary cutter for excavating earth and sand ahead (claim 10), The protruding portions can easily overlap each other.
This makes it possible to efficiently construct a large-section tunnel without performing a troublesome operation such as the injection of the chemical solution.

For example, when the segment assembling shape is substantially rectangular, the sectional shape of the shield machine main body is set to a shape protruding outward at a corner portion, and the auxiliary cutter is provided at the protruding portion. Item 1
1) The excavated sections can easily overlap each other at the corner portion.

According to the present invention, there is also provided a widening shield method for excavating while increasing the tunnel width by using the free-section shield machine according to any one of claims 2 to 5, wherein the revolving locus of the planetary cutter at the start of widening is defined. The excavation is performed by enlarging the shield machine body at a time by the target enlarging width, and thereafter gradually expanding the shield machine main body from the enlarging start width to the enlarging completion width.

According to this method, the width of the shield machine body gradually increases from the expansion start width to the expansion completion width.
Since the expansion of the excavation area by the planetary cutter (that is, the change of the revolving locus) is performed at the same time when the widening is started, the program required for controlling the revolving locus of the planetary cutter can be greatly simplified.

In particular, when the free-section shield machine according to the fourth aspect is used, it is only necessary to switch the current control mode to a control mode in which the width of the target trajectory is one rank higher than that at the start of widening, and thereafter. By digging while gradually widening the shield machine main body from the expansion start width to the expansion completion width (claim 13), it is possible to perform good widening excavation.

In the case where the free-section shield machine according to claim 8 or 9 is used, the revolving locus of the planetary cutter is expanded at once at the start of widening by the target widening, and then the main body of the shield machine has its front side shape changed. By digging while gradually widening the front end width of the shield machine main body from the expansion start width to the expansion completion width while making the front end width of the shield machine main body tapered in a direction larger than the rear side shape (claim 14), A large frontage of the shield machine body is secured while avoiding consolidation with the ground, so that sediment can be taken in during widening excavation satisfactorily, and smooth widening excavation can be realized.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings.

The shield machine shown here comprises a skin plate (shield machine body) 1 and a rotating body 2 provided at the front end thereof.

The skin plate 1 has a cylindrical shape as shown in FIGS. 1 to 6, and a ring composed of the segments SG is sequentially assembled in the rear inner region. The ring shape (two-dot chain line SG in FIGS. 1 and 12)
R) is set in a substantially square shape in this embodiment.

A plurality of shield jacks 37 are fixed inside the skin plate 1. In these shield jacks 37, the pushing portion 37a at the rod end pushes the front end surface of the foremost end segment SG by the extension operation. At this time, the reaction force received by the shield jack 37 becomes the driving force of the shield machine.

The skin plate 1 basically has a substantially square (substantially rectangular) cross-sectional shape, and a protruding portion (protruding portion) protruding outside the assembled shape of the segment SG is formed at a corner thereof. Part 1a is formed.

The skin plate 1 further includes a central skin plate 1C at the center in the left-right direction, and left and right outer skin plates 1L and 1R on both left and right sides.
And is divided into: The inner ends of the left and right skin plates 1L, 1R overlap the left and right side edges of the upper and lower walls of the central skin plate 1C from the outside. When the left skin plate 1L and the right skin plate 1R slide left and right with respect to the central skin plate 1C while maintaining the overlapping state, the entire width of the skin plate 1 is enlarged and reduced (solid line in FIG. 12). And two-dot chain line).

As means for expanding and contracting the skin plate 1, expansion and contraction width cylinders (expansion and contraction width means) 12F and 12R are provided at a front end portion and an intermediate portion of the skin plate 1, respectively. Since the mounting states of the expansion and contraction width cylinders 12F and 12R are the same, the mounting structure of the rear expansion and contraction width cylinder 12R will be described as an example.

As shown in FIGS. 1 and 6, on the inner surfaces of the skin plates 1C, 1L, and 1R, there are provided inwardly projecting frames 1d, and the shield jacks 37 are fixed to the frames 1d. Have been. The upper and lower frames 1d of the center skin plate 1C are provided with head support portions 1f projecting inward, and the frames 1d of the left and right skin plates 1L and 1R are provided.
, A vertically extending rod connecting frame 1e is fixed. The head support 1f and the expansion / contraction cylinder 1
The head side end of the 2R is connected by a spherical pair, and the rod connecting frame 1e and the rod end of the expansion / contraction cylinder 12R are connected by a spherical pair. The expansion and contraction of the expansion and contraction width cylinders 12R causes the left skin plate 1L and the right skin plate 1R to slide in the left-right direction with respect to the center skin plate 1C, and as a result, the skin plate 1 expands and contracts.

Further, in this embodiment, the front, rear, left and right
The expansion / contraction strokes of the two expansion / contraction cylinders 12F and 12R can be adjusted individually. Therefore, for example, by extending only the left expanding / reducing cylinders 12F and 12R, only the left skin plate 1L can be extended in the expanding direction. Also, the front-side expansion / contraction width cylinder 12
By making the amount of extension of F larger than the amount of extension of the rear-side enlarging / reducing cylinder 12R, it is possible to widen the skin plate 1 while keeping it in a tapered shape in which the front end width is larger than the rear end width. (The construction method by such expansion and contraction in a tapered shape will be described later in detail).

As described above, each of the enlarging / reducing cylinders 12
To enable individual adjustment of the stroke of F, 12R,
For example, a common hydraulic pressure source and each of the expansion and contraction width cylinders 12F and 12R
A directional control valve may be provided for each of the expansion and contraction width cylinders, and the directional control valve may be operated manually or by inputting a pilot signal or an electric signal. Further, the hydraulic pressure source can be shared with the shield jack 37.

A seal portion 8 is formed at the overlapping portion between the center skin plate 1C and the left and right outer skin plates 1L and 1R. The specific structure of the seal portion 8 can be variously set. In the illustrated example, as shown in FIG. 8 (a), a plurality of grooves 1b extending in the front-rear direction (in the depth direction in the figure) are formed on the inner surfaces of the left and right skin plates 1L, 1R. 1b is a sealing elastic body 8a
Is fitted. Then, these sealing elastic bodies 8
When a contacts the outer surface of the central skin plate 1C in an elastically deformed state, the seal is secured.

As shown in the figure, a seal plate 8c is fixed to the ends of the left and right skin plates 1L, 1R with a stopper 8d or the like, and the seal plate 8c is also bent and deformed to the center. If the outer surface of the skin plate 1C is kept in contact, a more reliable seal can be obtained. As shown in FIG. 8B, a plurality of types of elastic bodies 8a and 8b having different shapes may be used in combination.

Further, at the rear end of the skin plate 1, a tail seal 20 as shown in FIGS. 9 and 10 (a) to 10 (c) is provided. The tail seal 20 is for sealing a gap between the rear end of the skin plate and the segment SG.

More specifically, a seal mounting plate 21C extends rearward from the rear end of the central skin plate 1C, and a plurality of sealing elastic members 22C are fixed to the inner surface thereof. Are in direct contact with the outer surface of the segment SG. Further, from the rear ends of the left and right skin plates 1L and 1R, the seal mounting plate 21 is so covered as to cover the seal mounting plate 21C from outside.
L and 21R are extended, and a plurality of sealing elastic bodies 22L and 22R are fixed to the inner surface thereof. These sealing elastic bodies 22L and 22R are attached to the outer surface of the seal mounting plate 21C and the outer surface of the segment SG. In contact.

The rotating body 2 includes a front plate 3 and a rear plate 10.
The plates 3 and 10 are connected in the front-rear direction via a torque transmission shaft 2b, and a chamber 2a for taking in earth and sand is secured between the plates 3 and 10. Rear panel 10
A bearing 9 and a sealing material are interposed between the outer periphery of the skin plate 1 and the skin plate 1. Further, a ring 11 extends rearward from the rear face plate 10 of the rotating body 2, and a bearing and a sealing material are interposed between the ring 11 and a fixed ring 15 provided at a central portion of the skin plate 1. . With these bearings and the like, the entire rotating body 2 is rotatably supported around the central axis (the axis extending in the propulsion direction) of the skin plate 1.

A screw conveyor 30 is inserted into the inside of the fixing ring 15, and the excavated earth and sand in the chamber 2a is carried out backward by the screw conveyor 30.

As shown in FIG. 3, the front plate 3 has a substantially propeller shape in which a plurality of small-width plate-like members extend radially from a central portion thereof. A center bit 4 is provided at a center portion of the front plate 3, and a large number of cutter bits 5 are provided at a peripheral portion of the narrow plate-shaped body, thereby excavating a central circular portion of the excavated cross section. Main cutter 6
Is configured.

A plurality of (three in the illustrated example) planetary cutters 7 revolving with the rotation of the rotating body 2 are provided at positions between the small-width plate-like bodies of the front plate 3. These planetary cutters 7 are for excavating portions of the excavated cross section that are not excavated by the main cutter 6 (the outer peripheral portion excluding the central circular portion), have a cutter bit 7 a for excavation, and have a rotating body 2. Is mounted so as to be movable in the radial direction and to be able to rotate.

As a specific mounting structure, the same number of torsion bars as the planetary cutters 7 (rotational center axes of the planetary cutters) are provided on the rear face plate 10 of the rotating body 2 so as to penetrate the rear face plate 10 in the front-rear direction. ) 23 are attached, and a turning arm 24 is fixed to a front end of each torsion bar 23, and the planetary cutter 7 is rotatably provided at a turning end of each turning arm 24. Accordingly, each rotation arm 24 rotates with the rotation of each torsion bar 23, and each rotation causes each planetary cutter 7 to be displaced in the radial direction of the rotating body.

The input shaft protrudes rearward from the rear end of the torsion bar 23, and a planetary cutter driving pinion 18a is provided at the protruding end. When torque is input to the planetary cutter driving pinion 18a,
The torque is applied to each rotating arm 24 and torsion bar 23.
The planetary cutters 7 are transmitted to the planetary cutters 7 via a drive transmission mechanism (not shown) built therein, and as a result, each of the planetary cutters 7 is driven to rotate.

The means for inputting torque to the planetary cutter 7 and the rotator 2 are as follows.

A rotating body driving motor (rotating body driving means) 35 with a speed reducer is provided behind the ring 11 described above. The rotating body driving motor 35 is fixed to the skin plate 1, and a pinion 18 b provided on the output shaft of the rotating body driving motor 35 is connected to the ring 11 of the rotating body 2 via the drive transmission mechanism 17. ing. Further, a planetary cutter driving motor 45 is provided at a position circumferentially different from the position where the rotating body driving motor 35 is provided, and a pinion 18 d formed on an output shaft thereof is driven by the drive transmission mechanism 17 via the drive transmission mechanism 17. It is connected to the planetary cutter 7 side.

That is, in this shield machine, a torque for rotating the whole of the rotating body 2 is input from the rotating body driving motor 35 to the rotating body 2 via the drive transmission mechanism 17 and the planetary cutter driving motor 45 is rotated. Then, a torque for rotating the planetary cutter 7 is input to the planetary cutter driving pinion 18a through the same drive transmission mechanism 17.

The details of the drive transmission mechanism 17 are shown in FIG. Bearing support members 40 and 41 are fixed by bolts 42 to the inner peripheral edge of the ring-shaped bracket 13 fixed to the skin plate 1. Specifically, a bolt 42 is inserted into bolt through holes 13 a and 40 a provided in the bracket 13 and the bearing support member 40, and is screwed into a screw hole 41 a provided in the bearing support member 41, so that the bearing The support members 40 and 41 are fastened to the bracket 13 in a state where they are arranged in the axial direction (the left-right direction in the drawing). The fixing ring 15 is fixed to the front end surface (left end surface in the figure) of the bearing support member 41 using a bolt 43 in a cantilever state.

On the outer peripheral surfaces of the dual bearing support members 40 and 41,
Ring-shaped rotating body driving gear (rotating body drive transmitting member) 4
4 is rotatably supported. Specifically, large-diameter portions 40b and 41b are formed at the rear end of the bearing support member 40 and the front end of the bearing support member 41, respectively, and the front end of the bearing support member 40 is provided with a concave groove 40c that extends over the entire circumference. On the other hand, on the inner peripheral surface of the rotating body driving gear 44, a ridge 44a is formed over the entire circumference. And this ridge 4
A thrust bearing 45a is provided between a rear end surface of the large diameter portion 40b and a front end surface of the large diameter portion 40b, and a thrust bearing 45b is provided between a front end surface of the ridge 44a and a rear end surface of the large diameter portion 41b. A radial bearing 45c is provided between the outer peripheral surface of the ridge 44a and the outer peripheral surface of the concave groove 40c.

A tooth portion 44b is integrally formed on the outer peripheral surface of the rear half portion of the rotating body driving gear 44, and the front half portion is a small diameter portion 44c having a smaller diameter than the tooth portion 44b. The tooth portion 44b is connected to the pinion 1 on the rotating body driving motor 35 side.
8b (see FIG. 3), and a planetary cutter drive transmission gear 47 is rotatably supported on the outer peripheral surface of the small diameter portion 44c.

The planetary cutter drive transmission gear 47 includes a ring-shaped cutter-side gear member 48 and a motor-side gear member 49.
And both modules are set to values different from each other. The two gear members 48 and 49 are connected to each other by bolts 50 in a state where they are arranged in front and rear, and the motor-side gear member 49 is attached to the rotating body drive transmission gear 44 by a ball bearing 52 around the same axis as its rotation center axis. It is rotatably supported. The planetary cutter driving pinion 18a is engaged with the cutter-side gear member 48, and the pinion 18d of the planetary cutter driving motor 45 is engaged with the motor-side gear member 49 at the same time.

In this structure, the rotating body driving motor 3
5, the output torque is transmitted to the ring 11 on the rotating body 2 via the pinion 18b and the rotating body driving gear 44.
In addition, the output torque is input to the planetary cutter driving pinion 18a on the torsion bar 23 side via the pinion 18d and the planetary cutter driving gear 48 by the operation of the planetary cutter driving motor 45. That is, the output of the rotating body driving motor 35 causes the rotating body 2 to rotate.
, And the planetary cutter 7 is revolved, and at the same time, each planetary cutter 7 can be rotationally driven at a predetermined rotational speed by the output of the planetary cutter driving motor 45.

Further, the shield machine is provided with the rotating body 2
A planetary cutter operating means for integrally rotating each of the torsion bar 23 and the rotating arm 24 at the time of the rotation of the planetary gear. It is possible to cause the cutter 7 to draw a desired orbit. The structure is shown in FIG.

At the rear end of each torsion bar 23,
A control lever 29 extending in the radial direction is fixed.
A roller 28 is attached to a rotation end of the control lever 29 so as to be rotatable around a pin 27a.

On the other hand, the same number (three in this embodiment) of brackets 11a as the number of torsion bars 23 are provided on the outer periphery of the ring 11, and each of the brackets 11a is provided with a hydraulic cylinder so as to be swingable about a pin 27b. (Planetary cutter operating means) 33 is attached. The control lever 29 is connected to the movable end of the hydraulic cylinder 33 by the pin 2.
It is rotatably connected via 7c.

Therefore, by expanding and contracting each hydraulic cylinder 33, the control lever 29, the torsion bar 23, and the entire rotating arm 24 connected thereto can be rotated around the torsion bar 23 as a whole. The rotation allows the planetary cutter 7 to be displaced in the radial direction of the rotating body.

The guide rails 34C, 34L, 34R are provided on the inner surfaces of the center skin plate 1C, the left skin plate 1L, and the right skin plate 1R, respectively.
Has been fixed. At the joint between the guide rails 34C and 34L and the joint between the guide rails 34C and 34R, small-width projections 34 as shown in FIG.
a is formed, and even when the width of the skin plate 1 is expanded or contracted, the protruding portions 34a are always in the front-rear direction (vertical direction in FIG. 7).
, That is, the guide rail 34C and the guide rails 34L and 34R maintain continuity. In other words, the guide rails 34C, 34L, 34R
Ring-shaped guide rail consisting of skin plate 1
It is designed to expand and contract integrally.

The guide rail is provided on the hydraulic cylinder 3
When the stroke of No. 3 becomes excessive, each control lever 29
And restricts the outward rotation of the control lever 29 by contact with the roller 28 at the end of the planetary cutter 7, thereby preventing the radial position of the planetary cutter 7 from deviating from the allowable range to the outside. Therefore,
During normal operation, the guide rail and roller 2
8 does not come into contact.

FIG. 14 shows means for operating the stroke of each of the hydraulic cylinders 33 during rotation of the rotating body, that is, means for controlling the orbit of the planetary cutter 7.

In the figure, a rotating body rotation angle detector 38 is constituted by an encoder and the like, and detects the current rotating angle θ of the rotating body 2. The hydraulic cylinder stroke detector 39 is
The hydraulic cylinder 33 is provided in each of the hydraulic cylinders 33 and detects the expansion / contraction stroke d. These detection signals are input to an electronic control unit 70 including a microcomputer or the like.

The electronic control unit 70 stores a combination of the rotating body rotation angle θ and the hydraulic cylinder stroke d for causing the planetary cutter 7 to draw a desired revolution trajectory in the form of a function f (θ, d) or a data map. Then, the stroke d of the hydraulic cylinder 33 is determined based on the currently detected rotating body rotation angle θ, and a control signal is output to the hydraulic servo valve 32 in the hydraulic circuit to adjust the stroke of the hydraulic cylinder 33. is there. By this operation, the orbit of the planetary cutter 7 associated with the rotation of the rotating body 2 is appropriately controlled.

Further, the electronic control unit 70 has a control mode storage unit 72 and a hydraulic cylinder stroke control unit (planetary cutter operation control unit) 74 as a feature thereof, and a mode selection switch 76 is connected thereto. .

The control mode storage means 72 stores a total of M control modes up to a first control mode, a second control mode,..., An M-th control mode. In each control mode,
Different target trajectories are set for the orbit of the planetary cutter 7, and control data (function f (θ, d), data map, etc.) for realizing the target trajectory is assigned to each control mode. . That is, in this shield machine, a total of M target trajectories are set, and M control modes for executing the revolution trajectory control based on each target trajectory are prepared in advance.

In this embodiment, the shape process from the minimum width (solid line in FIG. 12) to the maximum width (two-dot chain line in FIG. 12) of the front end of the skin plate 1 is divided into M stages, corresponding to each stage. The revolving locus of the planetary cutter 7 corresponding to the shape of the front end of the skin plate is set as the target locus of each control mode. For example, in the first control mode, a target trajectory corresponding to the skin plate front end shape in the minimum width state is set, and in the Mth control mode, a target trajectory corresponding to the skin plate cross-sectional shape in the maximum width state is set.

The mode selection switch 76 is operated by an operator or the like to select an appropriate control mode from the M control modes. By the operation, the mode selection switch 76 inputs a mode selection signal to the hydraulic cylinder stroke control means 74. The hydraulic cylinder stroke control means 74 receiving this calls up the data relating to the selected control mode from the control mode storage means 72 and controls the stroke of each hydraulic cylinder 33 using the control data. In addition, information such as the currently selected control mode is displayed on the display 78.

In this embodiment, the “target trajectory corresponding to the skin plate cross-sectional shape” is defined as the planetary cutter revolution required to excavate an area one size larger than the skin plate cross-sectional shape by an appropriate extra depth. The trajectory is set.

In this shield machine, the main cutter 6
In addition to the planetary cutter 7, a void cutter 60 for excavating the front of the above-mentioned bulging portion 1 a (a skin plate portion protruding outward from a segment ring-shaped corner portion shown by a two-dot chain line SGR in FIG. 1 and the like) is provided. ing. The configuration is shown in FIGS. 3 and 13 (a) and 13 (b).

As shown in FIGS. 13 (a) and 13 (b), a thick boss portion 1h penetrating the skin plate 1 in the front-rear direction is formed on the front wall 1g at the periphery. A swing shaft 61 is inserted through the boss 1h, and is supported by a bearing 62 so as to be swingable around its own axis.

A cutter body 63 extending in the radial direction is fixed to the front end of the swing shaft 61, and a cutter bit 63 a is fixed to the peripheral edge of the cutter body 63. The swing shaft 61 is located substantially at the center of each of the bulging portions 1a having a substantially arc shape, and the cutter body 63 is arranged to oscillate in the region of each of the bulging portions 1a.

An operation lever 64 extending in the radial direction is fixed to the rear end of the swing shaft 61. The rod end of the oscillating cylinder 65 is connected to the oscillating end of the operating lever 64 via a pin 66, and the head-side end of the oscillating cylinder 65 is connected to the skin plate 1 via the pin 67. Are linked. Due to the expansion and contraction of the swing cylinder 65, the operation lever 64, the swing shaft 61, and the cutter body 63 swing integrally about the swing shaft 61, thereby excavating the front soil. .

Next, a shield method using the shield machine will be described. First, as a general example, a straight excavation method with a constant tunnel width will be described.

When excavation is performed, the width of the skin plate 1 and the target orbit of the planetary cutter 7 are set. Specifically, each of the expansion / contraction width cylinders 12F, 1F is adjusted so that the left and right widths of the skin plate 1 become a width suitable for a desired excavation cross-sectional shape.
The control mode in which the 2R expansion / contraction stroke is adjusted and a target trajectory corresponding to the cross-sectional shape of the skin plate 1 is set by operating the mode selection switch 76.

In this control mode, when the rotating body drive motor 35 and the planetary cutter drive motor 45 are operated, their outputs are input to the ring 11 and the planetary cutter drive pinion 18a via the drive transmission mechanism 17, and the rotating body 2
The rotation driving of the whole and the rotation driving of each planetary cutter 7 are performed in parallel.

As the rotating body 2 rotates, the planetary cutter 7
Also revolves integrally around the same axis, but during the rotation of the rotating body, each hydraulic cylinder 33
Is expanded and contracted in accordance with the rotation angle of the rotating body,
The planetary cutter 7 revolves along a revolving locus corresponding to the current skin plate front end shape (opening shape).

In parallel with such driving, the entire shield machine is propelled by the operating force of the shield jack 37, so that the center bit 4 and the cutter bit 5 rotating at the center excavate the central circular portion of the front ground. At the same time, the outer periphery is excavated by the cutter bit 7a of the planetary cutter 7 which revolves while drawing a specific trajectory around the periphery and rotates. As a result, a tunnel having a desired cross-sectional shape as a whole is excavated, and the excavated earth and sand is taken into the chamber 2a inside the skin plate 1 adjusted to the front end width corresponding to the excavated shape. This earth and sand is sequentially carried out backward by the screw conveyor 30, and finally carried out to the ground by a belt conveyor or the like (not shown).

The soil and sand in front of each bulging portion 1a protruding from the segment ring shape is also removed from each void cutter 60.
Therefore, the earth and sand can be converted into the improved ground without injecting a chemical solution or the like.

According to this shield machine, by adjusting the revolving trajectory of the planetary cutter 7 in accordance with the expansion and contraction width of the skin plate 1, regardless of the expansion and contraction width, good excavation and the excavated earth and sand inside the skin plate 1 are performed. Can be imported to Therefore, the degree of freedom in setting the tunnel shape is very high, and it is possible to widely meet various needs such as installation of an emergency stop zone, widening excavation, and curve excavation.

Further, in this embodiment, a plurality of control modes having different target trajectories are prepared in advance,
Since the operator can select an appropriate one of them, the excavation shape can be easily changed, and the program stored in the electronic control unit 70 can be simplified, thereby realizing the excavation at low cost. be able to.

In particular, in the shield machine according to this embodiment, as the target trajectory in each of the control modes, the front end of the skin plate 1 extends from the minimum width (solid line in FIG. 12) to the maximum width (two-dot chain line in FIG. 12). Since the orbit of the planetary cutter 7 corresponding to the skin plate cross-sectional shape corresponding to each stage when the shape process is divided into M stages is set,
It has a remarkable effect on the widening shield method that excavates while expanding the tunnel width. An example of the widening shield method will be described with reference to a work state diagram of FIG.

In this example, a predetermined widening point P shown in FIG.
The widening of the tunnel with the target widening amount δ is started from s, and excavation is performed such that the widening of the tunnel ends when the ground G1 is excavated from the point Ps by a predetermined distance Lw. Specifically, the following steps are taken.

1) First, when the front end of the planetary cutter 7 reaches the point Ps, the orbit of the planetary cutter 7 is enlarged at once by the target widening amount δ. At this time,
The difference between the target trajectory of the m-th control mode (1 ≦ m <M) stored in the mode storage unit 72 and the target trajectory of the (m + 1) -th control mode on the next rank is the target widening amount δ. If each target trajectory is set to be equal,
Widening excavation can be started only by switching the control mode to the control mode one rank higher.

2) As described above, the skin plate 1 is excavated in a state in which only the excavation area by the planetary cutter 7 is enlarged by one rank without widening. Then, when the propulsion is made by the distance ΔL from the front end of the planetary cutter 7 to the front end of the skin plate 1 (that is, the front end of the skin plate 1
), The front end of the skin plate 1 is widened before the rear end.
The stroke of the front-side enlarged / reduced width cylinder 12F is made larger than the stroke of the rear-side enlarged / reduced width cylinder 12R while giving a difference to the stroke of the 2R (that is, the skin plate 1 is tapered so that the front end width is larger than the rear end width). While keeping it large), the width of the skin plate 1 is gradually increased. If the skin plate is widened while maintaining the tapered shape in this manner, the opening at the front end of the skin plate 1, that is, the sediment intake port can be secured large while avoiding compaction between the rear portion of the skin plate 1 and the ground G <b> 1. Smooth widening excavation can be realized.

3) Finally, when excavating by the distance (ΔL + Lo + Lw) from the widening start point Ps, that is,
When the rear end of the shield machine body has passed the widening transition area,
The enlarging / reducing cylinders 12F, 12R during excavation so that the front and rear ends of the skin plate 1 are also widened by the target widening δ.
Adjust the stroke. From the point where such widening of the tunnel is completely completed, the assembly of the segment ring one size larger is started.

According to the above procedure, the excavation area is immediately expanded from the point Ps by the target width δ.
Since the front end width of the skin plate 1 for taking in the excavated earth and sand gradually increases, as a result, the tunnel excavation width expands in a tapered shape at the angle α in the widening region of the distance Lw. That is, in the widened area, an area G2 (mesh area in FIG. 15) that is excavated by the planetary cutter 7 but remains without being taken into the skin plate 1 is generated.

By repeating such widening excavation a predetermined number of times, the tunnel width can be finally expanded by a desired widening amount. Therefore, the larger the target widening amount δ is set, the smaller the required number of repetitions of the widening excavation, but if the target widening amount δ is excessively increased, the taper angle α exceeds the allowable angle, In addition, since the tail seal 20 cannot get over the segment step, it is necessary to set the target widening amount δ in consideration of such circumstances.

The stroke of each of the expansion / contraction cylinders 12F and 12R may be adjusted manually while monitoring each stroke, or may be adjusted automatically. Even in the case of manual operation, if the present strokes of the respective enlargement / reduction width cylinders 12F and 12R and the difference between the strokes and the target values SF and SR are displayed on the display 78, the work efficiency will be dramatically improved. .

In both cases of manual and automatic control,
Current shield machine excavation position and each expansion / contraction width cylinder 12F,
It is preferable to prepare a correspondence table between the stroke target values SF and SR of 12R. The excavation position is determined by the number n of the segment ring (the foremost ring) at which the shield jack 37 is receiving the reaction force, and the shield jack 3
7 can be specified by a combination with the stroke l. An example is shown in Table 1 below.

[0090]

[Table 1]

This table shows that the Ns-th segment SG
(Ns), the shield jack 37 receives a reaction force, and widening excavation starts at a point where the stroke 1 of the shield jack 37 is ls, and thereafter, every time the jack stroke l increases by Δl, the widening cylinder 12F,
The stroke target values SF and SR of the 12R are reviewed, and the distance ΔL from the widening excavation start point (in the table example, 2Δl <ΔL ≦
From the point excavated by 3Δl)
F and SR are changed from initial values SFo (SRo) to SF ₁ , SF ₂ ,
.. (SR ₁ , SR ₂ ,...), And finally the widening is completed before the assembly of the No. No. segment SG (No), that is, the stroke target values SF, S
An example is shown in which R reaches the final target values SFe and SRe. FIG. 16 shows a flowchart of this procedure.

First, as the control mode in the electronic control unit 70, the m-th control mode (1 ≦ m <N) corresponding to the cross-sectional shape before widening excavation is selected (step S in FIG. 16).
1). On the other hand, the stroke target values SF, SR of the front / rear expansion / contraction width cylinders 12F, 12R are respectively set to the initial target value SF.
o and SRo (step S2).

From the predetermined widening start point, that is, from the Ns-th segment SG (Ns) to the shield jack 37
Until the vehicle receives the reaction force and reaches the point where the jack stroke is 1 s (NO in step S3 or NO in step S5), the stroke target values SF, SR
Are maintained at the target values SFo and SRo, and the target value S
F, SR width cylinder 12F, 12R based on F, SR
Is adjusted (step S6). Each time excavation for one segment is completed (step S
Then, the count number (segment number) n of the assembly segment is updated (step S8).

After the shield jack 37 receives a reaction force from the expansion / contraction start point, that is, the Ns-th segment SG (Ns), and reaches a point where the jack stroke is ls (steps S3 and S4). , S5), the control mode of the electronic control unit 70 is shifted from the m-th control mode to the (m + 1) -th control mode one rank higher (step S9).

Then, until the segment number n reaches No, that is, the No. segment SG (N
o) Until the start of assembly (YE in step S10)
S), the stroke target values SF, S according to the above table from the segment number n and the shield jack stroke l.
R is read (step S11), and the actual strokes of the expansion and contraction width cylinders 12F and 12R are adjusted based on the target value (step S6). After the segment number n reaches No (NO in step S10), the stroke target values SF and SR are set to the final target values SFe and SRe, and are maintained (step S12).

In addition to such widening excavation, the present invention relates to FIG.
It is also effective for curve excavation as shown in Fig. That is, in such a curve excavation, especially when the curvature is relatively large, prevention of compaction between the skin plate 1 and the ground is an important issue. However, if the shield machine according to the present invention is used, a planetary cutter is used. By appropriately adjusting the excavation area by means of 7 and appropriately setting an appropriate amount of extra excavation, and more preferably, by projecting the skin plate 1 in a tapered shape, smooth curved excavation can be realized. Therefore, for example,
It is possible to realize good shield excavation with a simple configuration, without employing a complicated skin plate folding structure as disclosed in JP-A-331573.

In addition, the present invention can be embodied in, for example, the following forms.

In the above embodiment, the planetary cutter 7 is driven to rotate, but depending on the configuration, the driving of the planetary cutter 7 itself can be omitted. In other words, whether or not the planetary cutter 7 has a planetary cutter rotation drive unit that rotationally drives each planetary cutter 7 may be appropriately determined according to the configuration of the planetary cutter. Further, even in the case where the planetary cutter rotation driving means is provided, the present invention is not limited to driving the plurality of planetary cutters 7 collectively as described above, and for example, a motor may be provided for each planetary cutter 7.

In the above embodiment, the orbit of the orbit of the planetary cutter 7 is electrically controlled. However, for example, the guide rails 34C, 34L and 34R shown in FIG. If a guide rail whose shape expands and contracts is provided, it is possible to mechanically control the revolution trajectory by the guide of the guide rail. In the illustrated shield machine, the roller 2 at the tip of the control lever 29 is extended by the extension force of each hydraulic cylinder 33.
The planetary cutter 7 revolves while always pressing the guide cutter 8 against the guide rails 34C, 34L, 34R, so that the planetary cutter 7 has a locus corresponding to the shape of the guide rail,
That is, the orbit revolves along a locus corresponding to the cross-sectional shape of the skin plate 1.

The bulging portion (skin plate protruding portion) 1a and the void cutter 60 can be omitted as appropriate. However, by providing these, an excellent effect is obtained for excavation of a large-section tunnel (for example, a multi-lane underground tunnel) as shown in FIG.

That is, when excavating a tunnel having a section much larger than the section excavated by the shield machine alone,
The outer section of the large-section tunnel is excavated by joining a plurality of excavation sections (in the example shown, the machine A and the machine B each including the single main cutter of the type shown in the above embodiment and the main cutter are used). The method is used in combination with a plurality of multiple D machines equipped with multiple units, both of which have an expansion / contraction function), but if there is no protruding part from the segment ring in the excavated cross-sectional area of the shield machine, The excavated cross-sectional areas cannot overlap each other. Therefore, in this case, a troublesome operation such as injecting a chemical solution into the earth and sand remaining between the excavated sections becomes necessary. On the other hand, if a protruding excavation region (a region corresponding to the bulging portion 1a) by the void cutter 60 as described above is provided, the protruding excavation region is overlapped as shown in FIG. It is possible to efficiently construct a large-section tunnel without performing such operations.

In the above embodiment, the planetary cutter 7 is displaced in the radial direction of the rotating body by the rotation of the rotating arm 24. However, the planetary cutter 7 is linearly displaced in the radial direction of the rotating body. Alternatively, the planetary cutter 7 may be supported by the rotating body 2.

In the present invention, the width direction of the shield machine body (skin plate 1) is not limited. For example, the construction may be performed in such a manner that the shield machine body expands and contracts in the vertical direction.

In the present invention, a specific structure for enlarging or reducing the width of the shield machine body does not matter. For example, the shield machine body may be divided into a right part and a left part, and the other part may slide relative to one part so that the width can be enlarged or reduced. The structure of the enlarging / reducing means itself is not particularly limited, and in addition to using the hydraulic cylinder, for example, a motor and a drive transmission mechanism (such as a rack and pinion mechanism) may be combined.

When a plurality of control modes are stored in the control means such as the electronic control unit 70, the target trajectory set in each control mode corresponds to the shape in which the left and right skin plates 1L and 1R are uniformly extended. Not limited to For example, the control mode may include a mode having a target trajectory corresponding to a shape in which the left skin plate 1L or the right skin plate 1R is overhanged.

[0106]

As described above, the present invention is provided with a shield machine main body capable of expanding and contracting, a main cutter and a planetary cutter, and the orbit of the planetary cutter can be adjusted in accordance with the expansion and contraction width of the shield machine main body. Therefore, it is possible to increase and decrease the width of the excavated cross-sectional shape and increase the degree of freedom of the excavated cross-sectional shape, thereby providing an effect of flexibly responding to various needs.

[Brief description of the drawings]

FIG. 1 is a cross-sectional side view of a free-section shield machine according to an embodiment of the present invention.

FIG. 2 is a plan view of the free-section shield machine.

FIG. 3 is a front view of the free-section shield machine.

FIG. 4 is a sectional view taken along line AA of FIG. 1;

FIG. 5 is a sectional view taken along line BB of FIG. 1;

FIG. 6 is a sectional view taken along line DD of FIG. 1;

FIG. 7 is a view taken along line EE of FIG. 5;

FIGS. 8A and 8B are cross-sectional views showing an example of a sealing structure of a joint portion between a central skin plate and left and right skin plates in the free-section shield machine.

FIG. 9 is a view taken along the line FF in FIG. 1;

10A is a sectional view taken along line GG of FIG. 9, FIG. 10B is a sectional view taken along line HH of FIG. 9, and FIG. 10C is a sectional view taken along line II of FIG.

FIG. 11 is a sectional view showing a drive conversion mechanism for rotating and driving a rotating body and a planetary cutter in the free-section shield machine.

FIG. 12 is a conceptual diagram showing the expansion and contraction width of the skin plate.

13A is a partial cross-sectional side view showing a driving mechanism of a void cutter provided on the skin plate, and FIG. 13B is a rear view showing the driving mechanism.

FIG. 14 is a block diagram showing a functional configuration of an electronic control device provided in the free-section shield machine.

FIG. 15 is a cross-sectional plan view showing an example of a widening shield method using the free-section shield machine.

FIG. 16 is a flowchart showing a procedure of the widening shield method.

FIG. 17 is a cross-sectional plan view showing a curved excavation state using the free-section shield machine.

FIG. 18 is a view showing a construction example of a large-section tunnel using the free-section shield machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Skin plate (shield machine main body) 1C Center skin plate 1L Left skin plate 1R Right skin plate 1a Swelling part (protruding part) 2 Rotating body 6 Main cutter 7 Planetary cutter 12F Front expanding / reducing cylinder (front expanding / reducing means) 12R Rear Side expansion / contraction width cylinder (rear side expansion / contraction width means) 33 Hydraulic cylinder (planetary cutter operating means) 35 Rotating body drive motor (rotary body driving means) 60 Void cutter (auxiliary cutter) 70 Electronic control device (control means) 72 Control data storage means 74 Hydraulic cylinder stroke control means 76 Mode selection switch SG segment SGR Segment ring shape (segment assembly shape)

Claims (14)

[Claims] 1. A shield machine main body capable of expanding and contracting, a rotating body rotatably supported on an axis extending in a propulsion direction of the shield machine main body, and a rotating body integrally rotating with the rotating body to form a center of an excavated cross section. A main cutter for excavating a portion, a rotating body driving means for driving the rotating body, and supported by the rotating body so as to be displaceable in a radial direction thereof, and the main body of the excavated cross section is revolved by rotation of the rotating body. A planetary cutter for excavating a portion that is not excavated by the cutter, and control means for controlling the revolving locus of the planetary cutter, wherein the revolving locus of the planetary cutter controlled by the control means is adjusted according to the expansion and contraction width of the shield machine body. A free-section shield machine characterized in that it is configured to be adjustable. 2. The free-section shield machine according to claim 1, wherein said control means includes: planetary cutter operating means for displacing each of said planetary cutters in a radial direction of said rotating body; and said planets accompanying rotation of said rotating body. Planetary cutter operation control means for controlling the operation of the planetary cutter operation means during the rotation of the rotating body so that the orbit of the cutter coincides with the set target trajectory, wherein the target trajectory of the planetary cutter operation control means is A free-section shield machine characterized in that it is configured to be adjustable in accordance with the width of expansion and contraction of the shield machine body. 3. The free-section shield machine according to claim 2, wherein said planetary cutter operation control means includes control mode storage means for storing a plurality of control modes having different target trajectories, and selecting one of these control modes. A free-section shield machine configured to control the operation of the planetary cutter operating means based on the set control mode. 4. The free-section shield machine according to claim 3, wherein the front end shape of the shield machine body is divided into a plurality of stages from a minimum width shape to a maximum width shape, and the target trajectory in each of the control modes is determined. A free-section shield machine characterized in that the shape is set according to the shape of the front end of the shield machine body at each stage. 5. The shield machine according to claim 3, wherein the control mode has a target trajectory corresponding to a front end shape of the shield machine body when the shield machine body is widened to only one side as the control mode. A free-section shield machine characterized by including a mode. 6. A free-section shield machine according to claim 1, wherein said control means includes a guide means for guiding said planetary cutters so that each of said planetary cutters draws a predetermined orbit along with the rotation of said rotating body. A free-section shield machine provided on the shield machine main body, wherein a guide shape of the planetary cutter by the guide means is changed according to an expansion / contraction width of the shield machine main body. 7. The free-section shield machine according to claim 6, wherein a guide rail that expands and contracts integrally with the shield machine main body is provided on an inner surface of the shield machine main body, and the planetary gear is rotated during rotation of the rotating body. A free-section shield machine comprising a pressing means for pressing a cutter or a member displaced integrally with the planetary cutter against the guide rail. 8. The free-section shield machine according to claim 1, further comprising an expansion / contraction width means for enlarging / reducing the width of the shield machine main body, wherein the expansion / contraction width means is provided with the shield machine main body. A free-section shield machine characterized in that it can be expanded and contracted while being tapered so that the front end width is larger than the rear end width. 9. The free-section shield machine according to claim 8, wherein a plurality of enlargement / reduction means are arranged side by side in the front-rear direction of the shield machine body, and the enlargement / reduction width of the shield machine body by each enlargement / reduction means is independent in the front and rear. A free-section shield machine characterized by being configured to be able to be set. 10. A free-section shield machine characterized in that a part of the shield machine body protrudes outside the segment assembly shape and an auxiliary cutter for excavating earth and sand ahead at the protruding portion. 11. The free-section shield machine according to claim 10, wherein the segment assembly shape is substantially rectangular, and the cross-sectional shape of the shield machine main body is set to a shape protruding outward from a corner portion thereof. A free-section shield machine provided with the auxiliary cutter. 12. A shield construction method in which a tunnel is excavated while enlarging a tunnel width by the free-section shield machine according to any one of claims 2 to 5. A wide-width shield method using a free-section shield machine, characterized in that the shield body is excavated while gradually widening the main body of the shield machine from the expansion start width to the expansion completion width. 13. A shield method for excavating while increasing the tunnel width by the free-section shield machine according to claim 4, wherein the width of the target locus is higher by one rank than the current control mode at the start of the widening. A wide-width shield method using a free-section shield machine, which switches to the control mode, and then excavates while gradually widening the shield machine body from the start width of expansion to the completion width. 14. A shield method in which a tunnel is excavated while enlarging a tunnel width by the free-section shield machine according to claim 8 or 9. Thereafter, the excavation is performed while gradually widening the front end width of the shield machine main body from the enlargement start width to the enlargement complete width while making the shield machine main body tapered in a direction in which the front side shape is larger than the rear side shape. Widening shield method using a free-section shield machine.