JPH11294068A - Shielding construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce clearance with bedrock by boring along a tunnel external shape in the boring machine frong/rear parts by using the boring machine having an overbreak device and expanded width cylinders in the radial direction and capable varying an expanded width quantity in the shield longitudinal direction. SOLUTION: Overbreak is started from when a front face 20F of a shielding boring machine 20 reaches this side by the machine length L from a first taper starting point P1, and the front face 20F reaches the taper starting point P1 to become a maximum overbreak quantity. Next, expanded with cylinders 3L, 3R are expanded to perform excavation while expanding a longitudinal expanded width of the boring machine 20 until the front face 20F reaches a taper end point Q1. Next, boring is propelled by an expanded shield up to reaching a second taper starting point P2, and the boring is propelled by reducing the front face 20F until the tail 20T reaches the taper starting point P2. In that case, the overbreak is resumed from when the front face 20F advances to this side by the machine length L from a taper end point Q2, and afterwards, an overbreak quantity is reduced, and after the tail 20T passes through the taper end point Q2, the boring is ordinarily advanced. Therefore, clearance with bedrock can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield construction method for excavating tunnels having different cross-sectional shapes in an excavation direction using a shield machine capable of widening the tunnel in the left and right directions.

[0002]

2. Description of the Related Art Conventionally, as a construction method for enlarging a tunnel section, there are an open-cutting method and an underground cutting and expanding method. The excavation method not only needs to secure land for the excavated part,
Significant impact on road traffic and local environment. In particular, underground development is progressing in urban areas, and the construction depth of new tunnels must be increased, making it difficult to apply open-cutting methods. In addition, the underground cutting and spreading method is to solidify the surrounding ground to be expanded by auxiliary methods such as chemical injection method and ground freezing method, then remove the segment of the section to be expanded and enlarge the tunnel cross section, for that reason,
When the construction position is deep or the expanded section is long, the increase in construction cost and construction period due to the above-mentioned auxiliary construction method has been a serious problem. There is also a method in which an intermediate shaft is provided, the shield is drawn into the intermediate shaft, the shield is remodeled to have a required cross section, and re-excavation is performed. In this case, the intermediate shaft is indispensable. Therefore, for example, a technique of enlarging a tunnel cross section using a shield excavator having a circular cross section described in Japanese Patent Application Laid-Open No. 58-207494 and having a mechanism for widening the shield in a radial direction has been proposed. As shown in FIG. 15, a wide box 52 having a closed box structure is provided at the rear of a main cutter 51 provided on the front surface of the shield body 50.
(Bold line portion in the drawing), a plurality of widening excavating means 54 each having a cutter disk 53 for widening and excavating are arranged and housed in an arc shape inside the widening cylinder 52, and the widening is performed. The trunk 52 is moved in the radial direction of the shield body 50 to widen the tunnel. FIG.
(A) is a figure which shows the moving mechanism of the widening cylinder 52,
2 has a widening jack 55 for moving in the radial direction of the shield.
As shown in (b), the widening jack 55 is extended, and the sliding portion 52s of the widening cylinder 52 housed in the guide portion 50s of the shield body 50 is moved to the guide portion 50s.
Along with the shield body 50
From the radial direction. It should be noted that the shield propulsion jack 56 and the elector 57 on the widening cylinder 52 side
The rear body 50a of the widening cylinder 52 that accommodates the rear body 50a is also movable in the radial direction of the shield.
0a is also widened to the same shape as the widening cylinder 52, and a segment 58 is assembled at the rear of the shield.

[0003]

However, in the shield machine described above, the rigidity of the slide portion 52s and the guide portion 50s is not provided, so that the strength thereof is weak, and the length of the slide portion 52s is limited structurally. Therefore, there has been a problem that the widening amount cannot be increased. In addition, when the widening width of the tunnel is large, a method of excavating the tunnel by providing a tapered portion where the widening width gradually changes between the general portion of the tunnel having a circular cross section and the widening portion having the widened excavation cross section. However, in the conventional shield machine described above, the widening cylinder 5
2 and the rear trunk 50a have a structure in which the widening amount is changed independently of each other, so that the shield main body 50 at the time of widening has a shape which is widened in parallel in front and rear directions of the shield. The conventional shield excavator cannot be excavated along the shape of the tunnel provided with the tapered portion. In other words, when the conventional shield machine is excavated in the tapered portion with the left and right trunks parallel, not only does it need to increase the amount of extra excavation,
As a result of the excavation, there is a problem that a large clearance is generated between the shield excavator and the ground, and it is difficult to stabilize the ground.

[0004] The present invention has been made in view of the conventional problems, and provides a shield method capable of reducing the clearance between the shield and the ground when excavating a tunnel provided with a tapered portion. The purpose is to do.

[0005]

According to a first aspect of the present invention, there is provided a shield construction method, comprising: an extra excavation device which can be extended and contracted in a radial direction of a shield; and a pair of widening members which move to the left and right in the excavation direction of the shield. Using a shield excavator that can change the width of each of the widening cylinders in front of and behind the shield, and excavating the front and rear of the shield excavator along the outer shape of the tunnel. Is performed.

The shield method according to a second aspect of the present invention is characterized in that the above-mentioned excavation device performs extra excavation such that the excavation shape near the boundary between the general portion or the widened portion and the tapered portion becomes smooth. And

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a shield machine 20 according to an embodiment of the present invention.
1A is an overall sectional view, and FIG. 1B is a front view. In the figure, 1 is a main cutter mounted on the front surface of a shield machine 20 for excavating a face, and 2 is a pair of main cutters mounted on the main cutter 1 and capable of expanding and contracting in the radial direction of the main cutter 1 (radial direction of the shield). Equipment of 3L, 3
R is a left and right widening cylinder having an arc-shaped cross section that moves left and right respectively, 4 is a disk-shaped partition wall arranged at the rear of the main cutter 1, 5A and 5B are a plurality of sub-cutters 5k on the front surface. And a flat horizontal frame extending parallel to the axial direction of the shield machine 20. Reference numeral 5A denotes an upper horizontal frame constituting an upper trunk, and 5B denotes a lower horizontal frame constituting a lower trunk. The horizontal frames 5A, 5B
Constitutes the shield body 3 together with the left and right widening cylinders 3L and 3R. Further, 6 is provided inside the middle body of the shield, and the horizontal frame 5 is provided together with the partition 4.
A column for supporting A and 5B, 7 is the horizontal frame 5A and 5
B, attached to the inside of the shield of B
A slide jack for moving L and 3R to the left and right respectively, 8 is a shaft portion of the main cutter 1, 9 is a driving device of the main cutter 1, and 10 is a shield propulsion for pushing the segment 11 to advance the shield excavator. A jack, 12 is an erector for assembling the segment 11 into a ring shape, and 13 is the segment 11 and the shield machine 2
This is a tail seal for stopping water installed between the tail seal. In the upper and lower horizontal frames 5A and 5B, a driving device 5m for the sub-cutter 5k is provided at the rear of the sub-cutter 5k.
Is stored. Further, in order to simplify the drawing, a mud pipe 14 for sending high-pressure muddy water in front of the partition wall 4 and a drainage for sending earth and sand excavated by the main cutter 1 and the above muddy water to the rear of the shield. The mud pipe 15 is indicated by a two-dot chain line.

FIG. 2A is a sectional view taken along the line AA in FIG. 1A. Three sub-cutters 5k are provided at both ends of each of the horizontal frames 5A and 5B. Among the sub-cutters, the center sub-cutter is located on the front side of the other sub-cutters (see FIG. 1B). Further, a mud pipe 14 is provided at the center of the front surface of the upper horizontal frame 5A.
The agitator 16 for stirring the excavated earth and sand and the muddy water from the mud port 14a and the mud port 15 of the mud pipe 15 are provided in the center of the front surface of the lower horizontal frame 5B.
a. One of the outlets 15a in the figure is a spare outlet. Also, the left and right widening cylinders 3L,
Moving portions 3p and 3q are provided on a portion corresponding to the back side of the partition 4 of the 3R so as to be in close contact with the partition 4 with a waterproof seal (not shown) interposed therebetween. FIG.
In the sectional view taken along the line BB of FIG.
It is composed of two parallel bar-like members which are vertically built between the horizontal frames 5A and 5B between 5B. The drive device 9 for the main cutter 1 is provided concentrically with the shield body 3 at left and right three each.
Numeral 0 is provided concentrically inside the shield body 3. Specifically, the horizontal frame 5 which is an upper trunk and a lower trunk
A, the shield propulsion jack arranged inside 5B,
The other shield propulsion jack, which is arranged at the rear of the driving device 5m of the sub cutter 5k, moves the left and right widening cylinders 3
It is arranged inside L, 3R. In FIG. 1B, the erector 12 attached to the column 6 is omitted.

Next, the operation of the shield machine 20 configured as described above will be described. The excavation of the cutting face is performed by rotating the main cutter 1 while feeding high-pressure muddy water from a mud feed port 14a of a mud feed pipe 14 provided on the upper horizontal frame 5A, and a segment assembled in a ring shape by the shield propulsion jack 10. Press 11 to move the shield machine 20 forward. At this time, excavation of a long hole extending in the upper and lower horizontal directions by the sub-cutter 5k provided in the upper and lower horizontal frames 5A and 5B is performed at the same time. Excavated earth and sand
The slurry is stirred together with the mud by the main cutter 1 and the agitator 16, and is sent from the mud outlet 15 a through the mud pipe 14 to a sludge treatment device (not shown) outside the shield machine 20. When the excavation of one segment width is completed, the segment 11 is assembled using the erector 12 at the rear of the shield machine 20. A tail seal 13 is attached to a gap between the segment 11 and the shield machine 20 so as to prevent earth and sand and water from entering.

FIG. 3 shows a partition wall 4 in the front body of the shield, a column 6 built at right angles inside the middle body of the shield, and upper and lower parts mounted on and below the partition 4 and the column 6, respectively. FIG. 5 is a perspective view showing the configuration of a reinforcing frame composed of the horizontal frames 5A and 5B, and details of the arrangement of a slide jack 7 as a moving mechanism of the left and right widening cylinders 3L and 3R. The four slide jacks 7 are attached to the inside of the shield of the horizontal frames 5A and 5B, four at the top and four at the bottom.
Front and rear to move the right wide body slide jacks 7R and 7r, and the front and rear to move the left wide body 3L.
It consists of the rear two left body slide jacks 7L, 7l,
The right body slide jacks 7R, 7r and the left body slide jacks 7L, 7l are arranged alternately in the front and rear directions.
In FIG. 1, reference numeral 5P denotes a partition of the horizontal frames 5A and 5B, which are upper and lower trunks, and is formed integrally with the partition 4 (omitted in FIG. 1A). FIG. 4 is a perspective view showing a shield body (left and right widening bodies 3L, 3R) moving left and right in the shield excavation direction by the slide jack 7, and a main cutter is provided at the rear of the partition wall 4. Moving partition 3 having a rectangular notch for avoiding one of the shafts
p and 3q are located so as to overlap with the partition wall 4.
In addition, a plate-like extension extending in the axial direction of the shield is formed at the rear part of each of the moving bulkheads 3p and 3q, and above and below the left and right widening cylinders 3L and 3R, A jack receiving portion 3x for receiving the distal end portion of the slide jack 7 is provided at a position corresponding to the distal end portion of the slide jack 7 on the inner end surface of the extension portion inside the shield.
The slide jack 7 pushes the jack receiving portion 3x leftward and rightward of the shield, respectively, so that the left and right widening cylinders 3L and 3R move leftward and rightward, respectively, and the shield trunk 3 widens left and right. Is done. In addition, the moving partition walls 3p, 3
A water stop seal (not shown) is provided at a moving portion at the time of widening such as between q and the partition wall 4.

FIG. 5A is a view showing an example of the slide jack 7. The slide jack 7 extends and contracts a rod 7p by a cylinder 7a housed in a guide member 7b, and is shown in FIG. 5B. So, shield machine 20
Before and after the slide jacks 7R, 7L, 7r, 7
The amount of expansion and contraction of each rod 7p is appropriately set, and the amount of widening in the front and rear directions of the shield body (left and right widening bodies 3L and 3R) is changed. Note that even when the left and right widening cylinders 3L and 3R are not parallel, the jack receiving portion 3x is pressed uniformly,
The tip 7x of the rod 7p is formed as a curved surface so that the left and right widening cylinders 3L and 3R can move smoothly.
Reference numeral 7q denotes a receiving portion of the movable partition walls 3p and 3q, which is normally in contact with the jack receiving portion 3x.

FIGS. 6A and 6B are a front view and a sectional view taken along the line AA (see FIG. 1) of the shield machine 20 when the widening section is constructed. 3R is moved left and right by the slide jack 7 described above,
The over-digging device 2 provided on the main cutter 1 is driven to perform left and right widening excavation. Excavation device 2 is shown in FIG.
As shown in (a), an excavating cutter 2b is attached to the tip of an expanding and contracting arm 2a, and one excavating cutter 2b is attached to each of the symmetrical positions of the main cutter 1. Left and right widened cylinders 3L, 3R
Main cutter 1
The length of the arm 2a is controlled in synchronization with the rotation of the arm. At this time, the movable partition walls 3p and 3q are widened to the left and right while overlapping with the partition wall 4. Since the shield excavator 20 is reinforced by the above-mentioned reinforcing frame, the rigidity of the shield excavator 20 as a whole is high, and therefore, it is possible to sufficiently receive the reaction force received by the left and right widening cylinders 3L and 3R during widening excavation. it can.

FIG. 6 (c) is a view showing the state of the shield machine 20 during the widening construction in the sectional view taken along the line BB (see FIG. 1). The slide jack 71 pushes the left widening cylinder 3L and the right widening body slide jack 7r pushes the right widening cylinder 3R to the left and right, respectively.
At this time, the respective propulsion jacks 10 arranged inside the left and right widening cylinders 3L, 3R move left and right, respectively, integrally with the widening cylinders 3L, 3R. When the excavation of one segment width is completed, the segment 1
Assemble 1. FIG. 7A is a diagram illustrating a digging shape of a general portion by the shield machine 20, and FIG. 7B is a diagram illustrating a digging shape of the widened portion. In the figure, a backfill material made of a mixture of cement, water glass and the like is injected and filled into a tail void 17v (hatched portion in the figure) generated by excavation by the subcutter 5k. Further, as described later, the segment 11 used for the general portion and the widening portion is used in accordance with the excavation shape of the tunnel.

FIG. 8 shows a shield machine 2 according to the present embodiment.
FIG. 4 schematically shows how to excavate a tunnel 18 provided with a tapered portion in the excavation direction using 0, and the amount of widening of the shield body 3 in the left and right directions is measured before the shield excavator 20. Since it can be changed in the backward direction, the entire shield excavator 20 can be moved along the tunnel shape. Therefore, the amount of extra excavation can be reduced, and as a result of excavation,
The clearance between the shield machine and the ground can be reduced.

Next, a method of excavating a tunnel whose cross section changes in the left and right directions will be described in detail. FIG. 9 (a)
Is to provide a tapered portion with an extension of 10 m before and after the widened portion when providing a widened portion with a width of 6 m and an extension of 10 m for a general portion having a circular cross section with an outer diameter of φ5 m (tunnel width; w = 5 m) FIG. 21 is a diagram showing a planar shape of a tunnel when a tunnel is excavated, where 21 is a first general portion from a first taper start point P1, and 22 is a left and right direction from a point P1 to a first taper end point Q1. A first tapered portion where the tunnel width gradually increases, 23 is a widened portion in which the left and right tunnel width W from the first taper end point Q1 to the second taper start point P2 is W = 6 m, and 24 is A second tapered portion in which the tunnel width is gradually reduced leftward and rightward from the second taper start point P2 to the second taper end point Q2, 25 is a second general portion after the second taper end point Q2. It is. FIG. 9B is a diagram schematically illustrating the excavation position of the shield machine 20 and the history of the widening state. The shield machine 20 first includes the first general unit 21.
Then, the tunnel is excavated without expanding the widening cylinders 3L and 3R left and right. Then, from the time when the shield front 20F of the shield machine 20 has reached the front by the captain amount L from the first taper starting point P1 (a point p ₁ in FIG. 9 (a)), the outbreak device 2, FIG. 9 ( a) Excavation of the width indicated by the dotted line is started, and the amount of extra excavation is increased as the excavation proceeds.
When 0F reaches the first taper start point P1, the maximum remaining amount (for example, 81 mm) is set. After the shield front surface 20F reaches the first taper start point P1, tunnel excavation is performed while gradually widening the widening cylinders 3L and 3R so that the shield front surface 20F follows the planned tunnel shape. At this time, the surplus digging amount gradually decreases, and the shield front surface 20F moves to the first taper start point P1.
At point (point r _{1 in} FIG. 9 (a)) at the point when the aircraft has advanced by the length of the aircraft. Thereafter, until the shield front face 20F reaches the first taper end point Q1, the width of the shield front face 20F and the shield tail 20T is adjusted so as to follow the tunnel shape so that the shield front face 20F and the shield tail 20T extend along the tunnel shape. Excavation while gradually expanding each.

After the shield front surface 20F reaches the first taper end point Q1, the widened width of the shield front surface 20F is maintained at a constant width substantially equal to the widened width W of the widened portion 23, and the shield tail 20T is moved to the first position. Until the taper end point Q1 is reached, excavation is performed while gradually increasing the width of the shield tail 20T along the tunnel shape of the first tapered portion 22. When the shield tail 20T reaches the first taper end point Q1, the enlargement of the shield tail 20T is finished, and the shield tail 20F excavates with the enlarged shield having a constant width until the shield front face 20F reaches the second taper start point P2. Next, until the shield tail 20T reaches the second taper start point P2, the shield front face 20F is excavated while being reduced in accordance with the tunnel shape, and the shield front face 20F is moved forward by the length L from the second taper end point Q2. Excavation is resumed from the point in time (point p _{2 in} FIG. 9A). As shown by the dotted line in FIG. 9A, the amount of extra excavation is set to be the maximum amount of extra excavation (for example, 81 mm) at the second taper end point Q2. After the shield front surface 20F reaches the second taper end point Q2, the shield front surface 20F is kept constant in width and excavated while the shield tail 20T is continuously reduced.
At this time, the surplus digging gradually decreases, and the shield tail 20
When T reaches the second taper end point Q2 (FIG. 9A)
At point r ₂ ). Shield tail 20
After T passes the second taper end point Q2, normal excavation is performed.

[0019] The surplus section p ₁ shown by the dotted line in FIG.
Ｒr ₁ and p ₂ ｒr ₂ are provided because the shield excavator 2 is located near the first taper start point P1 and the second taper end point Q2.
Since the maximum outer trajectory of 0 is located outside the outer shape of the tunnel, in actual excavation, the clearance between the shield excavator 20 and the ground is ensured so that the shield excavator 20 can pass smoothly. is there. In addition, in the vicinity of the first taper start point P1 and the second taper end point Q2 where the surplus amount becomes maximum, the segment outer peripheral line can be rounded to further reduce the clearance.
In the vicinity of the first taper end point Q1 and the second taper start point P2, the minimum outer trajectory of the shield machine 20 is located inside the shield front face 20F. Since the clearance between the ridges is increased, the segment outer peripheral line is rounded also near the first taper end point Q1 and the second taper start point P2, so that the clearance can be further reduced. When the amount of extra excavation and the clearance are constant, the shield propulsion device 20 according to the present embodiment has a widening amount before the shield,
Later, the slope of the tapered portion can be increased as compared with a constant parallel expansion / contraction type shield propulsion device, so that the length of the tapered portion can be shortened.

FIG. 10A shows a state where the segments 11 are assembled in the general parts 21 and 25, and FIG.
Is the segment 1 in the tapered portions 22 and 24 and the widened portion 23.
FIG. 3 is a diagram showing a state in which 1 is assembled. In the general portions 21 and 25, segments 11A, 11B and 11K, which are RC segments made of a concrete material reinforced with reinforcing steel, are used. In the tapered portions 22 and 24 and the widened portion 23, the segments 11A and 11K and the steel segments are used. 11
M and 11N are used. The above segment 11
A, 11B, and 11K are arc-shaped segments having a fixed segment shape as shown in FIG. 11A, and the segment K is assembled into a ring shape by connecting the segments 11A and 11B with a ring bolt (not shown). Later, the segment is inserted between adjacent segments and connected by a ring bolt. The ring bolts are tightened so that force is transmitted between the assembled segments. The segment 11B is a segment adjacent to the segment K and has substantially the same shape as the segment 11A. However, the segment 11B is tapered in the insertion direction on the side of the connection portion with the segment K so that the segment K can be inserted. Segment 11M, 11N
Is a segment having a horizontal portion 11y between two arc portions 11x as shown in FIG.
1M is a segment adjacent to the front side of the segment K in the clockwise direction in the cross section, and the segment 11N is a segment adjacent to the rear side of the segment K. The length of the horizontal portion 11y of the segments 11M and 11N is the left of the tunnel,
It is set to a length according to the right widening amount, for example,
In places where the widening amount is large as shown in FIG.
1y long segments 11M and 11N (hatched portions in the figure)
Is used. In a tunnel section having a horizontal portion on the upper side or the lower side, a large bending moment is generated in the horizontal portion. Therefore, if a segment is used in which the horizontal portion has a joint that crosses the horizontal portion, a displacement occurs between the segments due to the bending moment, and water leaks from the joint or the tunnel due to water leakage, etc. May deteriorate early. Segment 11M, 11N
As described above, since there is no joint portion that crosses the horizontal portion, the rigidity of the assembled segment is large, and sufficient strength performance against the bending moment can be secured. Further, since the segments 11M and 11N are made of steel, the weight is lighter than that of the RC segment, and the handling is easy even when the horizontal portion is long.

When the segment is a segment used for the tapered portions 22 and 24, the segment width direction (digging direction) is formed in a tapered shape. For example, in the arc-shaped segment 11A, as shown in FIG.
The outer peripheral side in the segment width direction is formed in a tapered shape on both side surfaces 11z, 11z of the segment 11A so that a step does not occur between the rings on the outer surface of the segment. Alternatively, as shown in FIG. 13B, the cross section in the segment width direction is formed as a parallelogram so that no step is formed on both the inner and outer surfaces of the segment. However, the taper is not formed in the segment 11K, which is the K segment, and the segment K
No taper is formed on the side surface on the segment K side of each of the segments 11B, 11M, and 11N adjacent to. FIG. 14 is a view in which the segments having the parallelogram segment cross section are assembled into the widened portion. Since the outer surface of the segment 11A is formed in a tapered shape, the seal tail plate 13 of the tail seal 13 is formed.
Since a can be set so as to follow the outer periphery of the segment, the tail seal 13 can be attached without increasing the length of the seal brush 13b or increasing the number of hairs, and the water stoppage can be easily improved.

As described above, according to the present embodiment, the extra cutter 2 that can be extended and contracted in the radial direction of the shield is attached to the main cutter 1 and the column 6 that is built at right angles inside the middle body of the shield. And the partition 4 on the front body of the shield body
The upper and lower horizontal frames 5A and 5B having a sub-cutter 5k on the front surface are provided above and below, and the slide jack 7 provided inside the upper and lower horizontal frames 5A and 5B. The left and right widening cylinders 3L and 3R are moved to the left and right in the direction of excavation of the shield, so that the widening work is performed, so that the bulkhead 4, the columns 6 and the upper and lower horizontal frames 5A and 5B. The rigidity of the shield machine 20 as a whole is increased due to the reinforcing frame configured, and the widening cylinder 3L,
Since the reaction force received by the 3R can be sufficiently received, the widening work can be stably performed. Further, two slide jacks 7 are provided in the front and rear directions of the shield body, respectively.
When the tunnel 18 having the tapered portion is excavated, the entire shield excavator 20 is moved along the shape of the tunnel, because the width of the rightward widening can be changed in front and rear directions of the shield propulsion device 20. As a result, the clearance between the shield machine and the ground can be reduced.

In the present embodiment, the excavation is performed while continuously expanding and contracting the shield front face 20F and the shield tail 20T. However, the width of each of the shield front face 20F and the shield tail 20T is kept constant to a predetermined value. After excavating by the distance of 距離, the shield excavator 20 may be stopped and construction may be performed to change the respective widening amounts. In this case, the tail clearance is slightly increased, but the shield machine 20 includes the left and right widened cylinders 3L, 3L.
Since the forward movement is performed with the R widening amount and the excess digging amount by the extra digging device 2 controlled, the control of the extra digging device 2 and the slide jack 7 becomes easy.

[0022]

As described above, the shield method according to the first aspect uses a shield excavator in which the width of the left and right sides of the shield can be changed in front of and behind the shield, and before the shield excavator. Since the excavation work is performed with the part and the rear part along the outer shape of the tunnel, the entire shield excavator can be moved along the tunnel shape, and as a result of excavation, between the shield excavator and the ground Not only can reduce the clearance, but also can increase the slope of the tapered part compared to the conventional parallel expansion / contraction type shield propulsion machine.
The length of the tapered portion can be reduced.

The shield method according to claim 2 is
Since the extra excavation device performs extra excavation so that the excavated shape near the boundary between the general portion or the widened portion and the tapered portion is smoothed, the clearance at the boundary can be further reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a shield machine according to an embodiment of the present invention.

FIG. 2 is a sectional view of the shield machine according to the embodiment of the present invention.

FIG. 3 is a diagram showing a frame structure of the shield machine according to the embodiment of the present invention.

FIG. 4 is a diagram showing a widening cylinder of the shield machine according to the embodiment of the present invention.

FIG. 5 is a diagram for explaining a mechanism for moving the widening cylinder according to the embodiment of the present invention.

FIG. 6 is a diagram showing a front view of the shield machine when widening and a cross section of the shield body.

FIG. 7 is a diagram showing an excavation shape by the shield machine according to the embodiment.

FIG. 8 is a diagram showing a state of excavation in a tapered portion of the shield excavator according to the embodiment.

FIG. 9 is a diagram illustrating a method of excavating a tunnel provided with a tapered portion according to the present embodiment.

FIG. 10 is a diagram showing an assembled state of segments according to the embodiment of the present invention.

FIG. 11 is a diagram showing an example of a segment shape according to the embodiment of the present invention.

FIG. 12 is a diagram illustrating a segment assembled state according to the embodiment of the present invention.

FIG. 13 is an example of a segment having a taper according to the embodiment of the present invention.

FIG. 14 is a diagram showing a tunnel cross section of a tapered portion using a segment having a parallelogram cross section according to the embodiment of the present invention.

FIG. 15 is a diagram showing a configuration of a conventional shield machine.

FIG. 16 is a view showing a widening mechanism of a conventional shield machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main cutter 2 Extra digging device 3 Shield trunk 3L Left widening cylinder 3R Right widening cylinder 4 Partition wall 5A, 5B Horizontal frame 6 Post 7 Slide jack 8 (Main cutter) shaft 9 (Main cutter) drive 10 Shield propulsion jack 11 Segment 12 Elector 13 Tail seal 14 Mud feed pipe 15 Drain pipe 16 Agitator 20 Shield excavator 21, 25 General part 22, 24 Tapered part 23 Widening part

Continued on the front page (72) Inventor Shin Koda 2-1 Tsukudo-cho, Shinjuku-ku, Tokyo Tokyo Main Office (72) Inventor Tomoo Mimura 2-1 Tsukudo-cho, Shinjuku-ku, Tokyo Kumagaya Gumi Tokyo head office

Claims (2)

[Claims] 1. A tunnel in which a cross-sectional shape in an excavation direction is different, wherein a tunnel having a tapered portion having a widening width is provided between a general portion having a circular cross-section and a widening portion obtained by widening the cross-section in a radial direction. In this case, an extra excavation device that can expand and contract in the radial direction of the shield, and a pair of widening cylinders that move to the left and right in the direction of excavation of the shield are provided. A shield method, wherein a shield excavator that can be changed in a rearward direction is used, and excavation work is performed so that a front part and a rear part of the shield excavator are along the outer shape of a tunnel. 2. The excavation device according to claim 1, wherein the excavation device is controlled along a smooth excavation shape near a boundary between the general portion or the widened portion and the tapered portion, and the excavation is performed so that the excavation shape becomes smooth. The shield method according to claim 1, wherein: