JP4810964B2 - Shape retaining device for substantially U-shaped segment and method for retaining shape of generally U-shaped segment using this shape retaining device - Google Patents

Description

  The present invention relates to a shape holding device for a substantially U-shaped segment that is covered by excavation in a shield method, and a shape holding method for a substantially U-shaped segment using the shape holding device.

  In general, in the shield method that constructs a tunnel in the ground, when assembling the segment in the tail part of the shield machine, the outer periphery of the constructed segment is filled with backing material, but a predetermined strength can be obtained in a short time. For this reason, the segment constructed immediately before is subject to deformation due to earth pressure or dead weight from the natural ground, which often hinders connection with the latest segment being assembled. For this purpose, a shape holding device for holding the shape of the segment applied immediately before is used.

For example, Patent Document 1 discloses a support deck projecting rearward from the shield machine main body, a pair of left and right expansion jacks that are installed on both upper and lower sides of the support deck so as to be movable in the tunnel direction, and extend in the vertical direction. FIG. 2 shows a shape holding device including an arc-shaped upper expansion beam and a lower expansion beam that are attached to the upper end portion and the lower end portion of the expansion jack, respectively, along arcuate cross-sectional shapes. This shape holding device supports the vertical load acting on the segment due to earth pressure or natural weight from the natural ground by extending the expansion jack and bringing the upper expansion beam and the lower expansion beam into contact with the inner surface of the segment, This prevents deformation of the segment.
JP 2002-97899 A

  However, in the method using the shape holding device described in Patent Document 1, it is possible to hold a segment closed in a cylindrical shape such as a circle or a rectangle. In the case of holding the letter-shaped segment, there is a problem that the substantially U-shaped segment cannot be held because there is no member for the vertical expansion / contraction means to take a reaction force on the upper side of the substantially U-shaped segment. In addition, in the case of a closed segment, the entire outer peripheral part is restrained by a tail brush provided inside the tail part, and the installation position of the segment is maintained in the tail part. In the case of a substantially U-shaped segment, there is no upper segment, and only the both sides of the tail brush are constrained by the tail brush. There has been a problem that the axis of the U-shaped segment is greatly displaced. And if the tail clearance between the substantially U-shaped segment and the tail part expands beyond the design value due to the large deviation of the shaft center, the water stop function of the tail brush is lost, and the shield machine body There was a problem that groundwater and backfill materials flowed in. In addition, when the shaft center is greatly displaced, the substantially U-shaped segment comes into contact with the tail portion, and when the tail clearance is completely lost, the tail brush is crushed and the water stop function is deteriorated. .

  Therefore, the present invention has been made in view of the conventional problems as described above, and is substantially U-shaped capable of holding the shape and installation position of a substantially U-shaped segment having an opening on the upper side of a concave shape or the like. It is an object of the present invention to provide a shape holding device for a letter-shaped segment and a method for holding a shape of a substantially U-shaped segment using the shape holding device.

  In order to achieve the above object, a substantially U-shaped segment shape retaining device of the present invention is a shape retaining device for retaining the substantially U-shaped segment shape assembled when the shield machine is propelled, A vertical expansion / contraction means that is connected to the rear of the shield machine main body and can be expanded / contracted in the vertical direction, and is attached to the upper outer peripheral surface of the shield machine so as to project to the rear of the shield machine, and the vertical expansion / contraction means is extended. A reaction force receiving stand that serves as a reaction force material at the time is provided (first invention).

  According to the substantially U-shaped segment shape holding device of the present invention, by extending the vertical expansion / contraction means, the upper end portion of the vertical expansion / contraction means is brought into contact with the reaction force receiving base attached to the upper outer peripheral surface of the shield machine. It is possible to obtain a reaction force for maintaining the installation position of the substantially U-shaped segment. Therefore, the shape and installation position of the substantially U-shaped segment can be reliably held. In other words, the vertical clearance means can be expanded and contracted so that the axis of the shield machine and the substantially U-shaped segment can coincide with each other, so that the tail clearance between the approximately U-shaped segment and the tail portion is the design value. Within this range, the water stop function of the tail brush is maintained, and the inflow of groundwater and backfill material from the tail clearance can be prevented.

  Further, the mechanism of the shape holding device of the present invention simply attaches the reaction force receiving stand to the conventional shape holding device, and can be configured simply. Therefore, since the entire shape holding device is configured with a simple mechanism and the shape holding device does not occupy the space in the segment, a work space such as a scaffold for transporting and assembling the segment pieces is secured, and work efficiency is increased. Can be achieved.

The second invention is characterized in that in the first invention, further comprising left and right expansion / contraction means connected to the rear of the shield machine main body and capable of expanding and contracting in the left and right direction.
According to the shape holding device for the substantially U-shaped segment of the present invention, the horizontal shape of the substantially U-shaped segment can be securely held because the left and right extending / contracting means that can expand and contract in the left-right direction is provided. It becomes.

According to a third invention, in the first invention, the reaction force receiving stand is detachably attached to the shield machine.
According to the substantially U-shaped segment shape holding device of the present invention, the reaction force receiving stand can be attached to and detached from the shield machine, and therefore can be easily removed when the shield machine excavates in the ground. .

In a fourth aspect based on the first aspect, the vertical expansion / contraction means includes detection means for detecting an expansion / contraction amount, and maintains the shape and installation position of the substantially U-shaped segment by extending a predetermined expansion amount. It is characterized by that.
According to the substantially U-shaped segment shape holding device of the present invention, the shape and the installation position of the substantially U-shaped segment are accurately retained in order to extend the vertical expansion / contraction means based on a preset extension amount. Is possible.

In a fifth aspect based on the second aspect, the left / right expansion / contraction means includes detection means for detecting an expansion / contraction amount, and maintains a substantially U-shaped segment shape by extending a predetermined expansion amount. And
According to the substantially U-shaped segment shape holding device of the present invention, in order to extend the expansion amount of the left and right extension / contraction means set based on the design inner space of the approximately U-shaped segment, the shape of the approximately U-shaped segment Can be accurately maintained.

  According to a sixth aspect of the present invention, there is provided a method for maintaining the shape of the substantially U-shaped segment, which is connected to the rear of the shield machine main body and can be vertically expanded and contracted, and the shield so as to project to the rear of the shield machine. In a shape holding method for holding the shape of a substantially U-shaped segment using a shape holding device attached to the upper outer peripheral surface of the machine and having a reaction force receiving stand that becomes a reaction force material when the vertical stretching means extends. The upper and lower expansion / contraction means is extended so that the upper end portion and the lower end portion thereof are in contact with the reaction force receiving stand and the substantially U-shaped segment, respectively, and the shape and the installation position of the substantially U-shaped segment are maintained. It is characterized by.

According to a seventh invention, in the sixth invention, the shape of the substantially U-shaped segment is maintained using a shape holding device that is connected to the rear of the shield machine main body and further includes a left / right expansion / contraction means that can expand / contract in the left / right direction. In the shape retaining method, immediately before or immediately after the step of extending the vertical expansion / contraction means, the horizontal expansion / contraction means is extended so that the left and right end portions thereof are in contact with the substantially U-shaped segment, and the substantially U-shaped The shape of the mold segment is maintained.

The eighth invention is characterized in that, in the sixth or seventh invention, the shape of a substantially U-shaped segment installed in a section excavated so as to have an opening upward is performed by the shield machine. .
According to the shape maintaining method of the substantially U-shaped segment of the present invention, a shield machine can be used for an excavation method having an opening above, for example, an open-cut method.

  According to a ninth invention, in the sixth or seventh invention, when excavating a tunnel with the shield machine that can start from the ground and reach the ground, the shield machine starts from the ground before the shield machine Until the rear end enters the ground, or after the shield machine excavates the ground, the shield machine has an opening above the front end of the shield machine from the ground until the shield machine reaches the ground. The shape of the substantially U-shaped segment installed in the section is retained.

  According to the shape holding device and the shape holding method using the shape holding device of the present invention, it is possible to hold the shape and installation position of the substantially U-shaped segment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a front view of a rectangular shield machine according to the first embodiment of the present invention, and FIG. 2 is a side sectional view of the rectangular shield machine according to the first embodiment of the present invention. As shown in FIGS. 1 and 2, the shield machine 1 connects the hood part 3 that excavates the face at the front part in the traveling direction, the tail part 5 that performs lining at the rear part, and the hood part 3 and the tail part 5. A girder part 7 equipped with propulsion equipment and the like is also provided, and a skin plate 9 made of a rectangular cylindrical steel shell is provided for protecting each part described above against a load acting from the outside. Close to the inside of the skin plate 9, shield jacks 11 are provided at equal intervals.

  The shield machine 1 includes a plurality of rectangular main shields 15 which are arranged in a predetermined combination in the skin plate 9 vertically and horizontally, can be independently propelled, and can be independently driven. . The arrangement of the main shield 15 can be an appropriate combination according to the shape and size of the excavation cross section of the tunnel to be constructed. In the present embodiment, for example, the vertical (vertical) direction × the horizontal (horizontal) direction. = 2 (stage) × 3 (column). Each main shield 15 includes a rectangular shield main body 17 provided in the skin plate 9 so as to be movable back and forth, a slide jack 19 for moving the shield main body 17 forward and backward, and a cutter head provided rotatably on the front side of the shield main body 17. 23, a drive source 25 for driving the cutter head 23, and a power transmission mechanism 27 for transmitting the driving force of the drive source 25 to the cutter head 23. Are configured to be independently drivable.

  A segment assembling device 59 for assembling a substantially U-shaped segment 13 composed of a plurality of pieces is provided inside the tail portion 5, and the substantially U-shaped segment 13 is sequentially formed on the inner surface of the tunnel excavated by the segment assembling device 59. Assemble and build the inner wall with a generally U-shaped segment 13. A discharge device 57 for discharging the excavated earth and sand is connected to the girder unit 7.

  With the above-described configuration, the shield machine 1 that starts from the ground and excavates the ground, and can reach the ground, starts from the ground until the rear end of the shield machine 1 enters the ground, and the shield machine 1 After excavating the ground, the substantially U-shaped segment 13 is installed in a section having an opening upward from when the front end of the shield machine 1 appears from the ground until the shield machine 1 reaches the ground. Moreover, the shield machine 1 installs a rectangular cylindrical closed segment when excavating underground. Here, it is assumed that the substantially U-shaped segment 13 is obtained by removing the upper portion of the closed segment and the segments at both corners of the upper portion.

Hereinafter, a method of holding the shape of the substantially U-shaped segment 13 and the installation position will be described.
FIG. 3 is a front sectional view of the tail part 5 of the shield machine 1 according to the first embodiment of the present invention, and FIG. 4 is a side sectional view of the tail part 5 of the shield machine 1 according to the first embodiment of the present invention. is there.

  The shape maintaining device 31 of the substantially U-shaped segment 13 has one end connected to a vertical beam 33 (shown in FIG. 2) installed in the tail portion 5 of the shield machine 1 and the other end protruding rearward of the shield machine 1. A support frame 35 attached to the support frame 35 and attached to the upper outer peripheral surface of the shield machine 1 so as to project to the rear of the shield machine 1. And a reaction force receiving stand 38 which becomes a reaction force material when the vertical extending / contracting means 37 is extended.

  The support frame 35 includes a cylindrical support beam 45 and an extension beam 47 attached to both sides of the support beam 45 in an arm shape. The support beam 45 and the extension beam 47 are detachably connected. In order to secure the lower part of the support beam 45 as a work space for transporting and assembling the segment pieces, the support beam 45 is attached to the vertical beam 33 in a cantilever manner so as to be slightly above the center of the tunnel.

  The vertical expansion / contraction means 37 functions as an expansion / contraction mechanism, an outer cylinder 49 whose side surface is connected to one end of the extension beam 47, an inner cylinder 51 slidably inserted into the outer cylinder 49, and the inner cylinder 51 into the outer cylinder 49. An upper and lower jack 53 is provided for sliding in the vertical direction. The vertical expansion / contraction means 37 is swingable forward and backward in the advancing direction of the shield machine 1 at the upper end of each vertical expansion / contraction means 37 as a mechanism for contacting the substantially U-shaped segment 13 and the reaction force support base 38. A bracket 39 connected by pin connection, two sliding portions 43 having a sliding body 41 such as a slidable roller connected to the upper portion of the bracket 39, and the lower end portions of the vertical extending / contracting means 37. Two sliding parts 43 are provided. The sliding portion 43 has a plurality of sliding bodies 41 and is connected to the upper portion of the bracket 39 and the lower end portion of the outer cylinder 49 by pin coupling.

  The reaction force receiving stand 38 is made of a steel frame material such as a shape steel or a steel plate, and is attached to the upper surface of the shield machine 1 by welding.

  An extension member 40 such as H steel is detachably attached to the upper sliding portion 43 of the vertical extension / contraction means 37 with a bolt or the like. When the upper and lower jacks 53 are extended by a predetermined extension amount, the extension member 40 is attached. Comes into contact with the reaction force receiving stand 38. The upper and lower jacks 53 are provided with detection means for detecting the expansion / contraction amount of the jack, and the extension stops when the predetermined extension amount is reached. In this embodiment, the length from the upper end of the upper sliding body 41 to the lower end of the lower sliding body 41 with respect to the paper surface of FIG. 3 is closed when excavating the ground. The extension amount when the upper and lower jacks 53 are extended so as to be the same as the design inner space of the segment is set as the above-described predetermined extension amount.

  The installation position and shape of the substantially U-shaped segment 13 are maintained by extending the upper and lower jacks 53 by a predetermined extension amount, sliding the inner cylinder 51 upward with respect to the outer cylinder 49, and extending the upper side of the upper and lower jacks 53. The material 40 is brought into contact with the inner surface of the reaction force receiving base 38, and the lower sliding portion 43 of the upper and lower jacks 53 is brought into contact with the inner surfaces of the substantially U-shaped segments 13b and 13c. Here, by extending the upper and lower jacks 53 by a predetermined extension amount, the length from the upper end portion of the upper sliding body 41 to the lower end portion of the lower sliding body 41 via the upper and lower expansion / contraction means 37 is reduced. In order to be the same as the design inner space of the segment installed when excavating, the shape of the substantially U-shaped segment 13 in the vertical direction is maintained, and the substantially U-shaped segment 13 is the tail portion 5 of the shield machine 1. It is installed at a predetermined position.

  The shape holding device 31 extends the upper and lower jacks 53 after assembling the latest substantially U-shaped segment 13e in a state where the upper and lower jacks 53 are extended by a predetermined extension amount to hold the shapes of the substantially U-shaped segments 13b and 13c. When the shield machine 1 is propelled without expanding or contracting, the sliding part 43 slides along the inner surface of the substantially U-shaped segment 13 so that the shape holding device 31 moves forward together with the shield machine 1 and the sliding part 43 becomes substantially U-shaped. The mold segments 13c and 13d are moved to a state where the shape of the substantially U-shaped segment 13 is maintained.

  For example, when the excavation in the section from the start of the ground until the rear end of the shield machine 1 enters the ground is completed, and the excavation in the ground is started, the reaction force receiving frame 38 and the extension member 40 are used. Is removed from the shield machine 1.

  In the present embodiment, the method of installing the pair of left and right upper and lower expansion / contraction means 37 and holding the substantially U-shaped segment 13 has been described. However, the present invention is not limited to this method. A method of holding the center of 13 with one vertical expansion / contraction means 37 may be used, and the method is appropriately changed according to field conditions such as ground strength and a substantially U-shaped segment 13 empty cross-sectional area.

  Further, in the present embodiment, the method of attaching the reaction force support base 38 to the shield machine 1 main body by welding has been described. However, the method is not limited to this method, and for example, the reaction force support base 38 may be attached with a bolt, a nut, or the like. .

  Therefore, according to the shape retaining device 31 of the substantially U-shaped segment 13 of the present embodiment, the upper and lower expansion / contraction means 37 is extended, and the upper end of the vertical expansion / contraction means 37 is connected to the upper outer periphery of the shield machine 1 via the extension member 40. By coming into contact with the reaction force receiving base 38 attached to the surface, it is possible to obtain a reaction force for maintaining the installation position of the substantially U-shaped segment 13. Therefore, the shape and installation position of the substantially U-shaped segment 13 can be reliably and accurately held. That is, the vertical expansion / contraction means 37 can be expanded and contracted so that the axial centers of the shield machine 1 and the substantially U-shaped segment 13 can coincide with each other. The tail clearance falls within the design value range, the water stopping function of the tail brush 42 is maintained, and it becomes possible to prevent the inflow of groundwater and backfill material from the tail clearance.

  Further, the mechanism of the shape holding device 31 is simply to attach the reaction force receiving base 38 to the conventional shape holding device, and can be configured in a simple manner. Accordingly, since the entire shape holding device 31 is configured by a simple mechanism and the shape holding device 31 of the substantially U-shaped segment 13 does not occupy the space in the segment, the transportation of the segment pieces, the scaffold for assembly, etc. A work space is secured, and work efficiency can be improved.

  And since the reaction force receiving stand 38 is detachable with respect to the shield machine 1, it can be easily removed when the shield machine 1 excavates in the ground.

  Further, the shape holding device 31 can accurately hold the shape and the installation position of the substantially U-shaped segment 13 in order to extend a predetermined extension amount of the vertical expansion / contraction means 37.

  Next, a second embodiment of the present invention will be described. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 5 is a front sectional view of the tail portion 5 of the shield machine 1 according to the second embodiment of the present invention, and FIG. 6 is a view taken along the line A-A ′ of FIG. 5.

  As shown in FIGS. 5 and 6, the shape retaining device 61 of the substantially U-shaped segment 13 includes a support frame 35, a pair of left and right vertical expansion / contraction means 37, a bracket 39, a sliding portion 43, and a reaction force receiving base. 38, a pair of left and right expansion / contraction means 67 attached to each of the vertical expansion / contraction means 37 and extendable in the left and right directions, and a bracket that is swingably connected to the outer side of each of the left / right expansion / contraction means 67 in the tunnel direction. 39 and two sliding portions 43 connected to the outside of each bracket 39.

  The left / right expansion / contraction means 67 includes an outer cylinder 69 whose side surfaces are connected to the vertical expansion / contraction means 37, an inner cylinder 71 slidably inserted into the outer cylinder 69, and the inner cylinder 71 with respect to the outer cylinder 69 in the horizontal direction. And left and right jacks 73 for sliding them.

  The left and right jacks 73 include detection means for detecting the expansion / contraction amount of the jacks, and the extension stops when the predetermined extension amount is reached. In the present embodiment, the length from the left end of the left sliding body 41 to the right end of the right sliding body 41 with respect to the paper surface of FIG. Thus, the respective extension amounts when the left and right jacks 73 are extended equally are set as the above-described predetermined extension amounts.

  The installation position of the substantially U-shaped segment 13 and the holding of the shape in the vertical direction are the same as in the first embodiment by extending the upper and lower jacks 53 by a predetermined extension amount and causing the extension member 40 on the upper side of the upper and lower jacks 53 to be opposite. Abutting on the inner surface of the force receiving stand 38, the lower sliding portion 43 of the upper and lower jacks 53 is in contact with inner surfaces of the substantially U-shaped segments 13b and 13c.

  Further, the horizontal shape of the substantially U-shaped segment 13 is maintained by extending the left and right jacks 73 by a predetermined extension amount and sliding the inner cylinders 51 and 71 with respect to the outer cylinders 49 and 69. The sliding portions 43 are brought into contact with the inner surfaces of the substantially U-shaped segments 13b and 13c. Here, when the left and right jacks 73 are each extended by a predetermined extension amount, the length from the left end of the left sliding body 41 to the right end of the right sliding body 41 with respect to the paper surface of FIG. The design segment 13 is empty in the design.

  The shape holding device 61 assembles the latest substantially U-shaped segment 13e with the upper and lower jacks 53 and the left and right jacks 73 stretched by their predetermined extension amounts and the shapes of the substantially U-shaped segments 13c and 13d are retained. After that, when the shield machine 1 is propelled without expanding and contracting the upper and lower jacks 53 and the left and right jacks 73, the sliding portion 43 slides along the inner surface of the substantially U-shaped segment 13, so that the shape holding device 61 is moved together with the shield machine 1. It moves forward, and the sliding part 43 moves to the substantially U-shaped segments 13d and 13e, and maintains the shape of the substantially U-shaped segment 13.

  In the present embodiment, the left and right expansion / contraction means 67 is installed in the vicinity of the center axis of the tunnel and the method for holding the substantially U-shaped segment 13 is shown. However, the present invention is not limited to this position. The upper part or the lower part of the segment 13 may be held, and is changed as appropriate according to the field conditions such as the shape of the substantially U-shaped segment 13 and the ground strength. Furthermore, for example, a method of holding a plurality of locations such as an upper portion and a lower portion of the substantially U-shaped segment 13 may be used.

  Therefore, according to the shape holding device 61 of the substantially U-shaped segment 13 of the present embodiment, since it includes the vertical expansion / contraction means 37 that can be expanded and contracted in the vertical direction and the left and right expansion / contraction means 67 that can be expanded and contracted in the horizontal direction, It becomes possible to hold the shape of the substantially U-shaped segment 13 in the vertical direction and the horizontal direction. The shape of the substantially U-shaped segment 13 is accurately determined in order to expand the predetermined expansion amounts of the vertical expansion / contraction means 37 and the left / right expansion / contraction means 67 set based on the design space of the substantially U-shaped segment 13. It is possible to hold it.

  In all the above embodiments, the extension member 40 is provided, the upper and lower jacks 53 are extended, and the extension member 40 is brought into contact with the reaction force receiving base 38. However, the present invention is not limited to this. For example, the sliding body 41 of the upper and lower jacks 53 is attached to the reaction force receiving base 38 only by using the upper and lower jacks having a long expansion / contraction stroke that can contact the reaction force receiving base 38 without using the extension member 40. You may use the method to contact | abut.

  In all the embodiments described above, when the upper and lower jacks 53 are extended by a predetermined extension amount, the length of the upper and lower extension means 37 is the same as the design inner space of the closed segment, and the extension member 40 receives the reaction force. Although the method of contacting the gantry 38 has been described, the present invention is not limited to this. For example, if the predetermined extension amount of the upper and lower jacks 53 is lengthened and extended by the predetermined extension amount without using the extension member 40, A method of increasing the predetermined extension amount may be used so that the length of the expansion / contraction means 37 extends from the lower end surface of the reaction force receiving base 38 to the inner surface of the substantially U-shaped segment 13.

  In all of the above embodiments, the method of advancing the shape holding devices 31 and 61 in a state where the upper and lower jacks 53 are extended to hold the shape of the substantially U-shaped segment 13 has been described. Instead of this, a method of advancing the shape holding device 31 in a state where the upper and lower jacks 53 are contracted to release the holding of the substantially U-shaped segment 13 may be used.

  In all the above embodiments, the method of advancing the shield machine 1 main body and the shape holding devices 31 and 61 simultaneously has been described. However, the present invention is not limited to this. For example, the extension beam 47 is used as the support beam 45. A method may be used in which the shape holding devices 31 and 61 are slid along the support beam 45 and moved forward after the shield machine 1 is propelled by a predetermined distance. Further, when this method is used, a replaceable plate-like sliding material having a small friction coefficient is pasted on the upper surface of the extension member 40 in order to reduce the frictional resistance with the reaction force receiving base 38. It is desirable.

It is a front view of the rectangular shield machine concerning a first embodiment of the present invention. It is a sectional side view of the rectangular shield machine concerning a first embodiment of the present invention. It is a front sectional view of the tail part of the shield machine concerning a first embodiment of the present invention. It is a sectional side view of the tail part of the shield machine concerning a first embodiment of the present invention. It is a front sectional view of a tail part of a shield machine concerning a second embodiment of the present invention. It is a sectional side view of the tail part of the shield machine concerning a second embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shield machine 3 Hood part 5 Tail part 7 Girder part 9 Skin plate 11 Shield jack 13 U-shaped segment 15 Main shield 17 Shield main body 19 Slide jack 23 Cutter head 25 Drive source 27 Power transmission mechanism 31 Shape holding device 33 Vertical beam 35 Support frame 37 Vertical expansion / contraction means 38 Reaction force receiving base 39 Bracket 40 Extension material 41 Slide body 42 Tail brush 43 Slide part 45 Support beam 47 Extension beam 49 Outer cylinder 51 Inner cylinder 53 Vertical jack 57 Discharge device 59 Segment assembly device 61 Shape Holding device 67 Left / right telescopic means 69 Outer cylinder 71 Inner cylinder 73 Left / right jack

Claims (9)

A shape holding device for holding the shape of a substantially U-shaped segment assembled when the shield machine is propelled,
Up and down expansion and contraction means connected to the rear of the shield machine main body and capable of expanding and contracting in the vertical direction;
A substantially U-shaped reaction force receiving base that is attached to the upper outer peripheral surface of the shield machine so as to project rearward of the shield machine and serves as a reaction force material when the vertical expansion / contraction means extends. Shape-holding device for letter-shaped segments.   The shape maintaining device for a substantially U-shaped segment according to claim 1, further comprising left and right expansion and contraction means connected to the rear of the shield machine main body and capable of extending and contracting in the left and right direction.   The substantially U-shaped segment shape holding device according to claim 1, wherein the reaction force receiving stand is detachably attached to the shield machine.   The said vertical expansion-contraction means is provided with the detection means which detects the expansion-contraction amount, The shape and installation position of a substantially U-shaped segment are hold | maintained by extending | stretching a predetermined expansion amount. U-shaped segment shape retention device.   3. The substantially U-shaped segment according to claim 2, wherein the left / right expansion / contraction means includes a detection unit that detects an expansion / contraction amount, and maintains a substantially U-shaped segment shape by extending a predetermined extension amount. Segment shape retention device. Connected to the rear of the shield machine main body, and vertically extending and contracting means that can be expanded and contracted in the vertical direction, and attached to the upper outer peripheral surface of the shield machine so as to project to the rear of the shield machine. In a shape holding method for holding the shape of a substantially U-shaped segment using a shape holding device including a reaction force receiving stand that is a reaction force material of
The upper and lower expansion / contraction means is extended so that the upper end portion and the lower end portion thereof are in contact with the reaction force receiving stand and the substantially U-shaped segment, respectively, and the shape and the installation position of the substantially U-shaped segment are maintained. A method for maintaining the shape of a substantially U-shaped segment, characterized by: In the shape holding method that holds the shape of the substantially U-shaped segment using a shape holding device that is connected to the rear of the shield machine main body and further includes a left and right extending and contracting means that can expand and contract in the left and right direction.
Immediately before or immediately after the step of extending the vertical expansion / contraction means, the right / left expansion / contraction means is extended so that the left and right ends thereof are in contact with the substantially U-shaped segment, and the shape of the substantially U-shaped segment is maintained. The method for maintaining the shape of the substantially U-shaped segment according to claim 6.   The shape of the substantially U-shaped segment installed in the section excavated so as to have an opening above the shield machine is maintained. Shape retention method. When excavating a tunnel with the shield machine that can start from the ground and reach the ground, the shield machine starts from the ground until the rear end of the shield machine enters the ground, or the shield machine After the excavation of the ground, the shape of the substantially U-shaped segment installed in the section having an opening above the shield machine from the ground until the shield machine reaches the ground is maintained. The method for maintaining a shape of a substantially U-shaped segment according to claim 6, wherein the method is performed.

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