JP5404285B2 - Circular shape holding device - Google Patents

Description

  The present invention relates to a circular shape holding device that holds a shape by stretching a primary lining material such as a segment assembled in a ring shape or an inner mold frame from the inside during primary lining under tunnel construction.

  Conventionally, in a shield excavator, when a segment ring is formed by assembling segments (pieces), a perfect circle holding device as a shape holding device is often used to hold the segment ring in a perfect circle. Are known.

  For example, as shown in FIG. 9, the conventional perfect circle holding device is disposed on the rear deck of the shield excavator and has two arcuate segment support frames 100a and 100b. The upper and lower two segment support frames 100a and 100b are connected by a pair of left and right hydraulic jacks 101a and 101b that expand and contract in the vertical direction so that the top end portion is held with the bottom plate portion of the segment ring 102 as a reaction force receiver. (See Patent Document 1). In the figure, reference numeral 102 denotes a skin plate of the shield excavator.

  However, in the perfect circle holding device shown in FIG. 9, the top and bottom portions of the segment ring 102 are supported by the upper and lower segment support frames 100a and 100b. Since it does not hold a perfect circle around the circumference, there is a problem that the strength as designed cannot be obtained. The parts indicated by the distances L1 and L2 in FIG. 9 are not supported.

  Therefore, in recent years, Patent Document 1 has proposed a perfect circle holding device that can hold the perfect circle of the segment ring more accurately.

  As shown in FIG. 10, a plurality of (three in the illustrated example) arcuate members are connected in a ring shape by pins 200, and a pair of front and rear segment support frames 201 having the same curvature as the inner surface of a segment not shown. By extending the circumferential expansion / contraction portion 202 provided between the open ends of the segment support frame 201, the segment support frame 201 is brought into contact with the inner space of the segment as a perfect circle, and contracted in the opposite direction. It is to be separated from the sky surface in the segment. Further, when the perfect circle holding device is replaced, a plurality of (four in the illustrated example) are annularly arranged along the inner space of the segment, and both ends are connected between the pair of front and rear segment support frames 201. By expanding and contracting the portion 203, the refilling is performed by moving forward like a so-called scale insect.

Japanese Patent No. 4034207

  However, in the perfect circle holding device shown in FIG. 10, when the perfect circle holding device described above is replaced, even if the circumferentially extending / contracting portion 202 is contracted, the segment support frame 201 is separated from the inner space of the segment. Since the segment support frame 201 cannot be reduced in diameter around the entire structure, it is impossible to completely separate the entire circumference of the segment support frame 201 from the inner space of the segment.

  Therefore, when the segment support frame 201 is moved in the digging direction, the entire circumference of the segment support frame 201 cannot be completely lifted from the inner space of the segment, and parts that interfere with each other are generated. There was a problem that it could not be carried out smoothly.

  Further, since the perfect circle holding device shown in FIG. 10 obtains the shape holding force of the segment support frame 201 only by the extension force of the circumferential expansion / contraction part 202, there is a problem that the holding force is uneasy and the reliability of the device is low. There was also a point.

  Then, an object of this invention is to provide the circular shape holding | maintenance apparatus which can perform refilling smoothly and has high reliability of an apparatus.

In order to achieve such an object, the circular shape holding device according to the present invention includes:
A circular shape holding device that holds the shape by stretching the primary lining material assembled in a ring shape at the time of primary lining under tunnel construction,
A pair of left and right long support frames having a curvature corresponding to the primary lining material that is hinged at the bottom of the primary lining material and extends to the top of the primary lining material;
The base end portion is coupled to the upper end of the long support frame with a first pin, and the distal end side is overlapped with the second pin at two locations in the circumferential direction by overlapping in the front-rear direction on the ceiling portion of the primary lining material. A pair of front and rear short support frames having a curvature corresponding to the primary lining material which can be;
Two stopper pins that are located respectively above the joint portion by the first pin and can further pin-couple the long support frame and the short support frame;
Two push-up jacks that can push up the two short support frames individually;
Two expansion jacks capable of individually expanding the two long support frames;
A movable frame that supports the head portion of the push-up jack and the expansion jack and is movable in the tunnel digging direction;
It is provided with.

Also,
A pair of left and right support beam jacks are suspended from the movable frame, and a support beam having a curvature corresponding to the bottom of the pair of left and right long support frames connected to the hinge is supported by the support beam jack. It is characterized by that.

Also,
The first pin has play.

Also,
The pair of left and right long support frames are disposed so as to be displaced in the front-rear direction corresponding to the pair of front and rear short support frames, and are disposed so as to overlap in the front-rear direction at the hinge coupling portion. The width dimension of the contact surface with the primary lining material in the portion is set to be twice the width dimension of the contact surface with the primary lining material in the hinge coupling portion or the pin coupling portion.

Also,
The primary lining material is an inner mold used for lining with directly-cast concrete.

Also,
The primary lining material is a segment used in lining by a segment.

  According to the circular shape holding device according to the present invention, at the time of holding the shape, the pair of left and right long support frames hinged at the bottom of the primary lining material and the base end portions of the upper ends of the long support frames are respectively connected to the upper ends. The pair of front and rear short support frames connected by a single pin can be pressed against the inner peripheral surface of the primary lining material by extending the push-up jack and the expansion jack. It can be supported around the circumference and can hold a perfect circle.

  On the other hand, at the time of replacement, a pair of left and right long support frames hinged at the bottom of the primary lining material and the upper end of the long support frame with the second pins of the pair of front and rear short support frames removed. A pair of front and rear short support frames, each of which has a base end connected by a first pin, is displaced (reduced diameter) inward of the primary lining material by contracting the push-up jack and the expansion jack. By connecting the upper end of the scale support frame and the base end of the short support frame with the stopper pin in addition to the first pin, and then extending the push-up jack, the pair of left and right long support frames and this long support frame A pair of front and rear short support frames rigidly connected to each other are completely separated from the inner peripheral surface of the primary lining material. As a result, refilling can be performed smoothly, and the push-up force is shared by the two push-up jacks, so that the reliability of the apparatus is high.

1 is a schematic configuration diagram of a mud pressure shield excavator showing an embodiment of the present invention. It is a rear view of a mud pressure type shield excavator. 3A is an explanatory view of a circular shape holding device, FIG. 3A is a view as viewed from an arrow A in FIG. 2, FIG. 3B is a view as viewed from an arrow B in FIG. 2, and FIG. FIG. 4A and 4B are explanatory views of a circular shape holding device, in which FIG. 4A is a DD cross-sectional view of FIG. 2 and FIG. 4B is a cross-sectional view of FIG. It is operation | movement explanatory drawing at the time of replacement of a circular shape holding | maintenance apparatus. It is operation | movement explanatory drawing at the time of replacement of a circular shape holding | maintenance apparatus. It is operation | movement explanatory drawing at the time of replacement of a circular shape holding | maintenance apparatus. It is operation | movement explanatory drawing at the time of replacement of a circular shape holding | maintenance apparatus. It is a rear view of the conventional perfect circle holding device. It is a rear view of the conventional different perfect circle holding | maintenance apparatus.

  Hereinafter, the circular shape holding device according to the present invention will be described in detail with reference to the drawings by way of examples.

  1 is a schematic configuration diagram of a mud pressure shield excavator showing an embodiment of the present invention, FIG. 2 is a rear view of the mud pressure shield excavator, FIGS. 3 and 4 are explanatory views of a circular shape holding device, FIG. FIG. 8 to FIG. 8 are explanatory diagrams of the operation when the circular shape holding device is refilled.

  The tunnel excavator described in this embodiment is a mud pressure shield excavation that builds a tunnel while stabilizing the face by filling the chamber with excavated earth and sand and maintaining the inside of the chamber at a predetermined pressure. The machine employs a so-called ECL (Excluded Concrete Lining) method in which concrete is cast directly as a lining method, and lining is performed after curing and hardening.

  In this mud pressure shield excavator, as shown in FIG. 1, the excavator main body 11 has a front barrel 12 and a rear barrel 13 which are formed in a cylindrical shape having substantially the same diameter, and are connected to each other by a connecting shaft 14 so as to be bent right and left. It can be bent by a plurality of middle folding jacks 15 installed between them. A rotating ring 16 is rotatably supported on the front portion of the front barrel 12, and a cutter head 18 is connected to the rotating ring 16 via a connecting beam 17.

  The cutter head 18 is configured such that a plurality of cutter spokes 19 are arranged radially from the center portion, and the respective front end portions are connected by an outer peripheral ring 20. A fishtail cutter 21 is attached to the center of the cutter head 18, while a plurality of cutter bits 22 are attached to both sides of each cutter pork 19 along the longitudinal direction thereof. A copy cutter 23a and a rescue bit 23b for performing excessive digging are provided at the front end portion so as to freely appear and disappear.

  A ring gear 24 is fixed to the rear portion of the rotary ring 16, and a plurality of cutter turning motors (drive means) 25 are attached to the front body 12 of the excavator body 11. The drive gears 26 are meshed with the ring gear 24, respectively. Accordingly, when the cutter turning motor 25 is driven to drive the drive gear 26 to rotate, the cutter head 18 can be rotated via the ring gear 24, the rotating ring 16, and the connecting beam 17.

  In addition, a bulkhead 27 is provided at the front portion of the front cylinder 12 so as to be located behind the cutter head 18, and a chamber 28 is formed between the cutter head 18 and the bulkhead 27 for filling excavated earth and sand. Yes. A plurality of fixed stirring rods 29 project from the front side of the bulkhead 27, while a plurality of swirling stirring rods 30 project from the rear surface side of the cutter head 18. A part of the fixed stirring rod 29 is provided with a not-shown mud-material injection port for injecting a mud-material into the excavated soil in the chamber 28, and a not-shown chemical-solution injection pipe for injecting a chemical solution (consolidated material). Is provided. In the excavator main body 11, a screw conveyor 33 for carrying the excavated earth and sand to the outside is disposed, and the front portion is inclined downward to penetrate the bulkhead 27 and open into the chamber 28. ing.

  A ring garter 34 is fixed to the rear cylinder 13 of the excavator body 11 along the inner peripheral surface thereof, and a plurality of shield jacks (propulsion jacks) 35 are arranged on the ring garter 34 in the circumferential direction of the rear cylinder 13. The excavator body 11 advances by the reaction force by extending the shield jack 35 rearward and pressing the spreader 36 for pressing the inner mold against the existing inner mold M. be able to.

  A plurality of the inner molds M are assembled in a ring shape in the circumferential direction with a predetermined interval on the inner wall surface of the tunnel (the peripheral wall of the natural ground G). The concrete is cast directly into the space (concrete placement space E) between the peripheral wall of the inner mold M and the outer peripheral surface of the inner frame M assembled in a ring shape by a concrete placement device described later, thereby A lining tunnel is constructed. Further, the inner mold frame M is assembled in a plurality of stages in the longitudinal direction of the tunnel.

  Further, the ring garter 34 supports a turning ring 38 so as to be turnable along the circumferential direction of the inner wall surface of the tunnel, and can be driven and turned by a drive motor (not shown). The inner frame M is assembled to the turning ring 38. An erector 39 is provided. Further, a pair of left and right columns 40 are fixed to the ring gutter 34, and a substantially horizontal frame 41 is extended rearward from the column 40, and this frame 41 assists in assembling the inner mold frame M. A circular shape holding device 50, which will be described later, is mounted so as to be movable in the front-rear direction (tunnel excavation direction) together with the turning ring 51 for the worker.

  In addition, a plurality of transfer carts (not shown) are connected to the rear end of the gantry 41, and an inner mold release device for releasing the inner mold M at the rear stage, and the inner mold release device are connected to these transfer carts. A hoist 42 (see FIG. 2) for transporting the inner mold frame M removed in step 1 to the front of the tunnel, a power unit of a concrete placing device, and the like are mounted.

  Furthermore, between the rear trunk (skin plate) 13 and the inner mold frame M, there is a ring-shaped wife mold frame 43 that forms a concrete placement space E between the inner mold frame M and the peripheral wall of the natural ground G. In addition to being disposed, a plurality of wife formwork jacks 44 are juxtaposed along the circumferential direction at the front thereof, and the head base end portion passes through the ring gutter 34 and is connected to the inner peripheral portion of the rear barrel 13. On the other hand, the rod tip is connected to the end form frame 43. A rubber seal member (not shown) is mounted on the outer peripheral surface of the wife mold frame 43 along the circumferential direction, and a metal brush seal 45 is mounted on the inner peripheral surface of the wife mold frame 46 along the circumferential direction. Is installed.

  Therefore, by expanding and contracting the wife form frame jack 44, the ring-shaped wife form frame 43 can be moved back and forth. At this time, a seal member (not shown) presses against the inner peripheral surface of the rear barrel 13, and By pressing the brush seal 45 against the outer peripheral surface of the existing inner mold M assembled in a ring shape, it is possible to prevent water from entering the excavator body 11.

  A plurality of concrete placement pipes 46 are inserted into the end form frame 43 at a predetermined interval in the circumferential direction toward the rear of the excavation direction, and the concrete placement pipes 46 are closed valve devices 47 described later. It is possible to communicate with a concrete placement pipe (hose: concrete placement line) 48 by switching the switch. These concrete placement pipes 48 are communicated with a concrete supply source via the power unit on the transport carriage described above.

  Therefore, under the state where the concrete placement pipe 46 and the concrete placement pipe 48 are communicated with each other by the closing valve device 47, the ready-mixed concrete fed from the concrete supply source is connected to the concrete placement pipe 48 and the concrete placement pipe 46. It passes through the concrete placement space E described above. At this time, in the concrete placement space E, the concrete placement pipes 46 are sequentially placed in the circumferential direction.

  The inner mold M, the end mold 43, the concrete placing pipe 46, the concrete placing pipe 48, the closing valve device 47 and the like constitute a concrete placing apparatus.

  As shown in FIG. 2, the circular shape holding device 50 described above has an inner mold frame M (primary cover) assembled in a ring shape at the time of primary lining under tunnel construction by the mud pressure shield excavator described above. The construction material) is stretched from the inside to hold the shape.

  The circular shape holding device 50 includes a pair of left and right long support frames 53a and 53b that are hinged at the bottom of the inner mold frame M using pins 52 and extend to the top of the inner mold frame M, and these long support frames. The base ends of the frames 53a and 53b are pin-coupled with the first pins 54 with a little play, and the tip ends overlap in the front-rear direction (tunneling direction of the tunnel) at the ceiling of the inner frame M. And a pair of front and rear short support frames 56a and 56b that can be pin-coupled with the second pin 55 at two locations in the circumferential direction. The long support frames 53a and 53b and the short support frames 56a and 56b have a curvature corresponding to the inner mold frame M.

  The long support frames 53a and 53b are disposed to be displaced in the front-rear direction corresponding to the pair of front and rear short support frames 56a and 56b, and are respectively fitted to the corresponding short support frames 56a and 56b at the concave and convex portions. In addition to being pin-coupled (see FIGS. 3A and 3B), the hinge coupling portion overlaps in the front-rear direction and is hinge-coupled by the pin 52 in the same manner as the short support frames 56a and 56b. (See (c) of FIG. 3).

  Further, as shown in FIG. 4, the long support frames 53a and 53b are composed of aggregates 57a and 57b having an H-shaped cross section, reinforcing members 58a and 58b contacting the inner mold frame M, and ribs 59a and 59b. The width dimension of the general portions of the reinforcing members 58a and 58b is set to be twice the width dimension of the pin coupling portion with the hinge coupling portion and the short support frames 56a and 56b.

  Further, the pin coupling portions of the long support frames 53a and 53b and the short support frames 56a and 56b are positioned above the pin coupling portions by the first pins 54, and both are further pin-coupled by the stopper pins 60. It has come to be able to do.

  A portal-shaped movable frame 61 composed of a horizontal frame portion 61a and a pair of left and right vertical frame portions 61b is installed on the frame 41 so as to be movable in the tunnel excavation direction. That is, two pairs of front and rear wheels 62 are provided on both sides of the vertical frame portion 61b, and the wheels 62 roll on a pair of left and right rails 63 laid on the left and right sides of the gantry 41, respectively. It has become. As shown in FIG. 1, a pair of left and right vertical frame portions 61 b are connected to the tip ends of piston rods of a moving jack 64 with head portions supported on both the left and right sides of the gantry 41.

  A jack support block 65 is installed on the upper surface of the horizontal frame portion 61a, and two push-up jacks 66a and 66b capable of individually pushing up the two short support frames 56a and 56b are provided on the jack support block 65. Two expansion jacks 67a and 67b that are supported in the vertical direction and can individually expand the two long support frames 53a and 53b are supported in the horizontal direction. In FIG. 2, 68a and 68b are brackets fixed to the inner surfaces of the two long support frames 53a and 53b and connected to the piston rod tips of the two expansion jacks 67a and 67b, respectively. 69a and 69b are the two Spreaders connected to the piston rod tips of the push-up jacks 66a and 66b are in sliding contact with the inner surfaces of the two short support frames 56a and 56b.

  Support beam jacks 70a and 70b are respectively suspended inside the pair of left and right vertical frame portions 61b of the movable frame 61, and the pair of left and right hinges coupled to the tip ends of the piston rods of the support beam jacks 70a and 70b. A support beam 71 having a curvature corresponding to the lower ends of the long support frames 53a and 53b is supported. 2, the support beam jack 70a is contracted and the support beam 71 is separated from the lower ends of the pair of left and right long support frames 53a and 53b. In the right side of FIG. A state is shown in which the support beam jack 70a is extended and the support beam 71 pushes down the lower ends of the pair of left and right long support frames 53a and 53b.

  Since the cutter head 18 is rotated by the cutter turning motor 25, the shield jack 35 is extended and the excavator main body 11 is assembled over the plurality of rings in the longitudinal direction of the tunnel. The reaction force is taken and propelled (advanced), so that a number of cutter bits 22 attached to the cutter head 18 excavate the ground in front, and the excavated earth and sand are removed from the chamber 28 by the screw conveyor 33 etc. It is discharged outside.

  In synchronism with the propulsion (advance) of the excavator body 11, the inner mold frame M is assembled in a ring shape by the erector 39 and the circular shape holding device 50, and the true circle is held. Then, concrete is cast in the space between the assembled inner formwork M and the peripheral wall of the excavated tunnel almost continuously from the placement opening opened in the wife formwork 43. A lining wall is formed after curing. By repeating this, a tunnel having a predetermined length is excavated and formed.

  In the present embodiment, when holding the shape in the circular shape holding device 50, as shown in FIG. 2, a pair of left and right long support frames 53a and 53b hinged by pins 52 at the bottom of the inner mold frame M, A pair of front and rear short support frames 56a and 56b whose base ends are coupled to the upper ends of the long support frames 53a and 53b by the first pins 54 are respectively connected to push-up jacks 66a and 66b and expansion jacks 67a, By extending 67b, it presses against the inner peripheral surface of the inner mold frame M assembled in a ring shape. Further, by extending the pair of left and right support beam jacks 70a and 70b and pushing down the lower ends of the pair of left and right long support frames 53a and 53b hinged by the support beam 71 by the pin 52, the pair of left and right long beams are supported. The lower end portions of the scale support frames 53a and 53b are pressed against the inner peripheral surface of the bottom portion of the inner mold frame M. Note that the stopper pin 60 is not used when maintaining this shape.

  As a result, a tensile force is applied to the inner mold frame M from the upper, lower, left and right directions, and the inner mold frame M can be supported over the entire circumference of the inner mold frame M, so that a perfect circle can be reliably held. Note that the support beam 71 is not an essential component and may be used as necessary.

  On the other hand, at the time of replacement, as shown in FIGS. 5 to 8, first, the pair of left and right support beam jacks 70a and 70b are contracted, and the pair of left and right long support frames 53a in which the support beam 71 is hinged by the pins 52 are used. , 53b. For convenience, FIGS. 5 and 7 show the behavior of the long support frame 53a and the short support frame 56a on the left side (on the drawing), and FIGS. 6 and 8 show the long support frame 53b and the short support on the right side (on the drawing). The behavior of the support frame 56b is shown.

  Next, with the second pin 55 removed from the pair of front and rear short support frames 56a and 56b (a pin hole is shown in FIGS. 5 to 8), the pin 52 is formed at the bottom of the inner mold frame M. A pair of left and right long support frames 53a and 53b which are hinged and a pair of front and rear short support frames 56a and 56b whose base ends are coupled to the upper ends of the long support frames 53a and 53b by first pins 54, respectively. Then, the push-up jacks 66a and 66b and the expansion jacks 67a and 67b are contracted to be displaced (reduced diameter) inward of the inner mold frame M (see FIGS. 5 and 6). At this time, the relative displacement between the pair of left and right long support frames 53a and 53b and the pair of front and rear short support frames 56a and 56b is effectively absorbed by play (backlash) of the first pin 54.

  Next, the upper ends of the pair of left and right long support frames 53a and 53b and the base end portions of the pair of front and rear short support frames 56a and 56b are coupled to the first pin 54 by the stopper pin 60 and then pushed up again. 66a and 66b are extended to push up a pair of left and right long support frames 53a and 53b and a pair of front and rear short support frames 56a and 56b rigidly connected to the pair of left and right long support frames 53a and 53b, respectively (FIG. 7). And FIG. 8).

  Accordingly, the pair of left and right long support frames 53a and 53b and the pair of front and rear short support frames 56a and 56b are completely separated from the inner peripheral surface of the inner mold frame M (the gaps G1 to G1 in FIGS. 7 and 8). As a result, the circular shape holding device 50 can be refilled smoothly by extending the movable jack 64 and moving the movable frame 61 in the tunnel digging direction.

  Further, in this embodiment, the push-up force is shared by the two push-up jacks 66a and 66b, so that a stable push-up force can be obtained at the time of replacement, and the reliability of the apparatus is high. Furthermore, the width dimension in the general part of the reinforcing members 58a and 58b in the long support frames 53a and 53b is set to a dimension that is twice the width dimension in the pin coupling part with the hinge coupling part and the short support frames 56a and 56b. Therefore, a stable shape retention force can be obtained by increasing the pressing area. Furthermore, when the shape is maintained, the inner mold (piece) M can be smoothly conveyed by the pair of left and right hoists 42 in the inner space between the pair of left and right support beam jacks 70 a and 70 b and the support beam 71.

  Needless to say, the present invention is not limited to the above-described embodiment, and various modifications such as automating the attachment and detachment of the stopper pin 60 are possible without departing from the scope of the present invention. Moreover, it can replace with the mud pressure type shield excavator which employ | adopted the ECL method, and can apply this invention to the mud pressure type shield excavator which employ | adopted the lining method by a segment. Furthermore, the tunnel excavator provided with the circular shape holding device according to the present invention is not limited to the mud pressure shield excavator, but may be a mud shield excavator, a mechanical shield excavator, a tunnel boring machine (TBM), or the like.

DESCRIPTION OF SYMBOLS 11 Excavator main body 12 Front trunk 13 Rear trunk 15 Folding jack 18 Cutter head 34 Ring gutter 35 Shield jack 36 Spreader for inner-frame press-fit 41 Mount 42 Hoist 43 Wife mold 44 Wife mold jack 47 Stop valve device 46 Concrete placement pipe 48 Concrete placement pipe 50 Circular shape holding device 51 Swivel ring for worker 52 Pin 53a, 53b Long support frame 54 First pin 55 Second pin 56a, 56b Short support frame 60 Stopper pin 61 Movable frame 62 Wheel 63 Rail 64 Moving jack 66a, 66b Push-up jack 67a, 67b Expansion jack 70a, 70b Support beam jack 71 Support beam E Concrete placement space G Ground mountain M Inner formwork

Claims (6)

A circular shape holding device that holds the shape by stretching the primary lining material assembled in a ring shape at the time of primary lining under tunnel construction,
A pair of left and right long support frames having a curvature corresponding to the primary lining material that is hinged at the bottom of the primary lining material and extends to the top of the primary lining material;
The base end portion is coupled to the upper end of the long support frame with a first pin, and the distal end side is overlapped with the second pin at two locations in the circumferential direction by overlapping in the front-rear direction on the ceiling portion of the primary lining material. A pair of front and rear short support frames having a curvature corresponding to the primary lining material which can be;
Two stopper pins that are located respectively above the joint portion by the first pin and can further pin-couple the long support frame and the short support frame;
Two push-up jacks that can push up the two short support frames individually;
Two expansion jacks capable of individually expanding the two long support frames;
A movable frame that supports the head portion of the push-up jack and the expansion jack and is movable in the tunnel digging direction;
A circular shape holding device comprising:   A pair of left and right support beam jacks are suspended from the movable frame, and a support beam having a curvature corresponding to the bottom of the pair of left and right long support frames connected to the hinge is supported by the support beam jack. The circular shape holding device according to claim 1.   The circular shape holding device according to claim 1, wherein the first pin has play.   The pair of left and right long support frames are disposed so as to be displaced in the front-rear direction corresponding to the pair of front and rear short support frames, and are disposed so as to overlap in the front-rear direction at the hinge coupling portion. The width dimension of the contact surface with the primary lining material in the portion is set to be twice the width dimension of the contact surface with the primary lining material in the hinge coupling portion or the pin coupling portion. , 2 or 3 circular shape holding device.   5. The circular shape holding device according to claim 1, wherein the primary lining material is an inner mold used for lining with direct-stretch concrete.   6. The circular shape holding device according to claim 1, 2, 3, 4, or 5, wherein the primary lining material is a segment used in lining with a segment.

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