JP4819013B2 - Formwork for lining made of cast-in-place concrete - Google Patents

Description

  The present invention relates to a formwork for lining made of cast-in-place concrete.

Conventionally, in order to construct a lining made of cast-in-place concrete in a tunnel excavated in the ground, a steel formwork made of a plurality of rings adjacent in the axial direction of the tunnel is used (see Patent Document 1). . Each ring is composed of a plurality of pieces adjacent in the circumferential direction of the tunnel.
JP-A-4-216798

  Each piece has a substantially rectangular frame that is open on both sides, and a plate that is fixed to one side of the frame. Two adjacent pieces are connected to each other by a bolt that penetrates the side of the frame of one piece and the side of the frame of the other piece, and a nut that is screwed to the bolt.

  When constructing the lining, the formwork is arranged in the tunnel with an interval from the ground to the inside thereof, and concrete is placed between the formwork and the ground. Thereafter, the ring closest to the tunnel entrance is disassembled and moved to the face side of the ring closest to the face of the tunnel. Thereafter, the moved ring is assembled, a new ring is formed adjacent to the ring closest to the face, and concrete between the new ring and the ground is placed. In this way, the lining is constructed from the wellhead side to the face side.

  The piece includes a disassembling piece in which a distance between the two side portions in the circumferential direction gradually increases from the outside in the radial direction of the tunnel toward the inside. Since the distance between the both sides of the dismantling piece gradually increases from the outside in the radial direction toward the inside, the dismantling piece is moved toward the center of the tunnel when disassembling the ring closest to the wellhead Thus, the dismantling piece can be removed from between two adjacent pieces. When disassembling the ring closest to the wellhead, first, the dismantling piece is removed from between two adjacent pieces, and then pieces other than the dismantling piece are removed.

  Since the distance between both side portions gradually increases from the outside in the radial direction toward the inside, the dismantling piece receives the pressure from the concrete when the concrete is placed between the mold and the ground. Try to move towards the center of the tunnel. At this time, there is a possibility that the bolt breaks due to a shearing force acting on the bolt that joins the disassembly piece and the adjacent piece. When the bolt breaks, the dismantling piece moves toward the center of the tunnel and comes out between two pieces adjacent to the dismantling piece. For this reason, construction of the lining cannot be performed safely.

  An object of the present invention is to prevent the dismantling piece from slipping out between two adjacent pieces.

  In the present invention, the disassembling piece has a protruding portion extending in the circumferential direction on each side portion, and the piece adjacent to the disassembling piece has a receiving portion for receiving the protruding portion of the disassembling piece on its side portion. When the dismantling piece moves toward the center of the tunnel, the overhanging portion of the disassembling piece comes into contact with a portion defining the receiving portion of the adjacent piece so that the disassembling piece stops This prevents the dismantling piece from slipping out between two adjacent pieces.

  The formwork according to the present invention includes a plurality of rings adjacent in the axial direction of the tunnel, and each ring is a plurality of pieces adjacent in the circumferential direction of the tunnel, and the length in the circumferential direction is the face of the tunnel. It consists of a plurality of pieces including at least one dismantling piece that gradually increases from the side toward the wellhead side. In the dismantling piece, the length between one side portion and the other side portion in the circumferential direction gradually increases from the outside in the radial direction of the tunnel toward the inside, and extends in the circumferential direction on each side portion. The overhanging portion includes a side portion that is separated from the side portion to the side, and a bottom portion that is spaced outward from the bottom portion of the dismantling piece in the radial direction. The piece adjacent to the dismantling piece has a receiving portion for receiving the overhang portion of the disassembling piece on a side portion thereof, and the receiving portion is spaced inward from the side portion of the adjacent piece. Defined by a side portion and a bottom portion spaced radially outward from a bottom portion of the adjacent piece, and the radial length of the side portion defining the receiving portion of the adjacent piece is It is longer than the radial length of the side portion of the overhang portion of the dismantling piece.

  Since the radial length of the side portion of the adjacent piece is longer than the radial length of the side portion of the dismantling piece, the bottom portion of the adjacent piece is separated from the bottom portion of the disassembling piece. Spacing is provided inwardly in the radial direction. Since the bottom portion of the adjacent piece is located at a position spaced radially inward from the bottom portion of the dismantling piece, the dismantling piece is subjected to pressure from concrete and the tunnel When moving toward the center, the bottom part of the dismantling piece comes into contact with the bottom part of the adjacent piece and the dismantling piece stops. For this reason, the piece for dismantling does not slip out between two adjacent pieces.

  Since the length between both side portions of the dismantling piece gradually increases from the outside in the radial direction toward the inside, the disassembling piece can be moved toward the center of the tunnel. Since the circumferential length of the dismantling piece gradually increases from the face side to the wellhead side, the dismantling piece can be moved from the face side to the wellhead side. When removing the dismantling piece from between two adjacent pieces, first the dismantling piece is moved toward the center of the tunnel, and then the dismantling piece is directed from the face side to the wellhead side. Move.

  A distance maintaining means is disposed between the bottom portion of the overhang portion of the dismantling piece and the bottom portion defining the receiving portion of the adjacent piece.

  The adjacent piece includes a substantially rectangular frame that is open on both sides, and a plate that is fixed to one side of the frame, and a side portion of the frame extends from the plate in the radial direction. A side wall portion extending inward and a bottom wall portion extending laterally from the side wall portion, wherein the side portion and the bottom portion defining the receiving portion of the adjacent pieces are respectively the side walls of the frame body A bolt that penetrates the bottom wall portion, which is arranged from the bottom wall portion of the frame body toward the bottom portion of the overhang portion of the dismantling piece. And a nut screwed to the bolt and fixed to the bottom wall portion.

  The adjacent piece includes a substantially rectangular frame that is open on both sides, and a plate that is fixed to one side of the frame, and a side portion of the frame extends from the plate in the radial direction. The side portion defining the receiving portion of the adjacent piece comprises the side wall portion of the frame, and the spacing maintaining means penetrates the side wall portion of the frame. And a spacer inserted between the bottom portion of the overhang portion of the dismantling piece and the bottom portion defining the receiving portion of the adjacent piece.

  The spacing maintaining means includes a spacer inserted between the bottom portion of the projecting portion of the dismantling piece and the bottom portion defining the receiving portion of the adjacent piece from the wellhead side toward the face side. Can be.

  The plurality of pieces includes an assembly piece whose length in the circumferential direction gradually increases from the pit side toward the face side.

  According to the present invention, the dismantling piece has the overhanging portion extending in the circumferential direction on each side portion, and the adjacent piece has the receiving portion for receiving the overhanging portion of the dismantling piece on its side portion. The bottom portion defining the receiving portion of the adjacent piece is present at a position spaced radially inward from the bottom portion of the overhang portion of the dismantling piece, When the demolition piece receives pressure from concrete and moves toward the center of the tunnel, the bottom portion of the demolition piece comes into contact with the bottom portion of the adjacent piece, and the demolition piece stops. For this reason, the dismantling piece does not slip out between two adjacent pieces, and the lining can be constructed safely.

  As shown in FIG. 1, in order to construct a lining 12 made of cast-in-place concrete in a tunnel 10, a mold 16 made up of a plurality of rings 14 adjacent in the axial direction of the tunnel 10 is used. The tunnel 10 is excavated in the ground 20 using a shield 18. The formwork 16 is disposed with an interval inward from the ground 20, and the lining 12 is constructed by placing concrete between the formwork 16 and the ground 20.

  As shown in FIG. 2, each ring 14 includes a plurality of pieces 22 adjacent in the circumferential direction of the tunnel 10. The plurality of pieces 22 includes a disassembling piece 24 whose length in the circumferential direction gradually increases from the face side of the tunnel 10 (upward in the drawing) toward the wellhead side (downward in the drawing), and the circumferential length from the wellhead side. And an assembly piece 26 that gradually increases toward the face side. Each piece 22 is made of a metal such as steel or cast iron. In the illustrated example, the plurality of pieces 22 include one disassembly piece 24, but instead, the plurality of pieces 22 may include a plurality of disassembly pieces 24. However, the case where all of the plurality of pieces 22 are dismantling pieces 24 is excluded.

  As shown in FIGS. 3 and 4, in the disassembly piece 24, the length between the one side portion 28 and the other side portion 30 in the circumferential direction gradually increases from the outside in the radial direction of the tunnel 10 toward the inside. And each side part 28 and 30 has the overhang | projection part 32 extended in the said circumferential direction. The overhang portion 32 includes a side portion 34 that is laterally separated from the side portions 28 and 30, and a bottom portion 38 that is radially outwardly separated from the bottom portion 36 of the dismantling piece 24.

  The disassembly piece 24 has a substantially rectangular frame 40 that is open on both sides, and a plate 42 that is fixed to one side of the frame. The side portion of the frame 40 includes a first side wall portion 40a extending inward in the radial direction from the plate 42, a bottom wall portion 40b extending inward from the first side wall portion, and the radial direction from the bottom wall portion. And a second side wall portion 40c parallel to the first side wall portion 40a (FIG. 3). The side portion 34 and the bottom portion 38 of the overhanging portion 32 of the disassembly piece 24 are respectively composed of a first side wall portion 40a and a bottom wall portion 40b of the frame body 40, and the side portions 28 and 30 of the disassembly piece 24 are It consists of the 2nd side wall part 40c.

  The piece 44 adjacent to the dismantling piece 24 has a receiving part 48 for receiving the overhanging part 32 of the dismantling piece 24 on its side 46. The receiving portion 48 is defined by a side portion 50 that is spaced inwardly from the side 46 of the adjacent piece 44 and a bottom portion 54 that is spaced radially outward from the bottom 52 of the adjacent piece 44. ing. The radial length 56 of the side portion 50 defining the receiving portion 48 of the adjacent piece 44 is longer than the radial length 58 of the side portion 34 of the overhanging portion 32 of the dismantling piece 24.

  The side portion 46 of the adjacent piece 44 is in contact with the side portions 28 and 30 of the disassembly piece 24, and the side portion 50 of the adjacent piece 44 is in contact with the side portion 34 of the disassembly piece 24. Since the radial length 56 of the side portion 50 of the adjacent piece 44 is longer than the radial length 58 of the side portion 34 of the dismantling piece 24, the bottom portion 54 of the adjacent piece 44 is the dismantling piece. Spaced from the bottom portion 38 of 44 inwardly in the radial direction.

  Similar to the disassembly piece 24, the adjacent piece 44 includes a substantially rectangular frame body 60 that is open on both sides, and a plate 62 that is fixed to one side of the frame body. The side portion of the frame 60 includes a first side wall portion 60a extending inward in the radial direction from the plate 62, a bottom wall portion 60b extending sideways from the first side wall portion, and the radial direction from the bottom wall portion. And a second side wall portion 60c parallel to the first side wall portion 60a (FIG. 3). The side portion 50 and the bottom portion 54 that define the receiving portion 48 of the adjacent piece 44 are respectively composed of the first side wall portion 60 a and the bottom wall portion 60 b of the frame body 60, and the side portion 46 of the adjacent piece 44 is the side portion 46 of the frame body 60. It consists of the second side wall portion 60c.

  Since the length between both side portions 28 and 30 of the dismantling piece 24 gradually increases from the outside in the radial direction toward the inside, the disassembling piece 24 is a piece to which the bottom portion 38 of the disassembling piece is adjacent. It can be moved towards the center of the tunnel 10 until it touches the bottom portion 54 of 44. Since the circumferential length of the dismantling piece 24 gradually increases from the face side toward the wellhead side, the dismantling piece 24 can be moved from the face side toward the wellhead side. For this reason, the dismantling piece 24 is first moved toward the center of the tunnel 10 and then moved from the face side toward the wellhead side, so that the dismantling piece 24 is located between two adjacent pieces 44. Can be removed.

  The disassembling piece 24 and the adjacent piece 44 include a bolt 64 passing through the second side wall portion 40c of the frame body 40 of the dismantling piece 24 and the second side wall portion 60c of the frame body 60 of the adjacent piece 44, and the bolt They are coupled to each other by a screwed nut 66 (FIG. 3). Of the two adjacent rings 14, the disassembly piece 24 of one ring 14 and the piece 22 of the other ring 14 are the end 68 of the frame 40 of the disassembly piece 24 of one ring 14 and the other ring. 14 pieces 22 are connected to each other by bolts 70 (FIG. 3) penetrating through the ends of the frame (not shown) of the pieces 22 and nuts (not shown) screwed to the bolts.

  Since the distance between the side portions 28 and 30 gradually increases from the outside in the radial direction toward the inside in the dismantling piece 24, the concrete is placed when the concrete is placed between the mold 16 and the ground 20. It is going to move toward the center of the tunnel 10 under the pressure of. At this time, a shearing force acts on the bolt 64 that connects the disassembly piece 24 and the adjacent piece 44 and the bolt 70 that connects the disassembly piece 24 and the piece 22 of the other ring 14, so that these bolts 64 are connected. , 70 may break. When the bolts 64 and 70 are broken, the dismantling piece 24 moves toward the center of the tunnel 10. Since the bottom portion 54 of the adjacent piece 44 exists at a position spaced radially inward from the bottom portion 38 of the dismantling piece 24, the dismantling piece 24 even if the dismantling piece 24 moves. The bottom portion 38 of the metal plate contacts the bottom portion 54 of the adjacent piece 44 and the dismantling piece 24 stops. For this reason, the disassembling piece 24 does not come out from between the two pieces 44 adjacent thereto, and the lining 12 can be constructed safely.

  A distance maintaining means 72 is disposed between the bottom portion 38 of the overhanging portion 32 of the dismantling piece 24 and the bottom portion 54 defining the receiving portion 48 of the adjacent piece 44. The spacing maintaining means 72 maintains a spacing 74 between the bottom portion 38 of the dismantling piece 24 and the bottom portion 54 of the adjacent piece 44.

  The spacing maintaining means 72 is arranged from the bottom wall portion 60b of the frame body 60 of the adjacent piece 44 toward the bottom wall portion 40b of the frame body 40 of the disassembly piece 24, and the bottom wall of the frame 60 of the adjacent piece 44 A bolt 76 that penetrates the portion 60 b and a nut 78 that is screwed to the bolt and is fixed to the bottom wall portion 60 b of the frame body 60 of the adjacent piece 44. By rotating the bolt 76 relative to the nut 78 and moving the bolt 76 in the radial direction, the amount of protrusion of the bolt 76 from the bottom wall portion 60b of the frame body 60 of the adjacent piece 44 can be changed.

  In order to maintain the space 74 between the bottom portion 38 of the dismantling piece 24 and the bottom portion 54 of the adjacent piece 44 by the space maintaining means 72, the dismantling piece 24 can be There is no movement toward the center of the tunnel 10. This eliminates the risk that the dismantling piece 24 moves toward the center of the tunnel 10 and the concrete flows into the ring 14 through the gap between the dismantling piece 24 and the adjacent piece 44. The safety at the time of construction of the work 12 can be improved. Further, since the distance maintaining means 72 prevents the dismantling piece 24 from moving toward the center of the tunnel 10, the bolt 64 and the disassembling piece 24 that connect the disassembling piece 24 and the piece 44 adjacent to the disassembling piece 24 and the other No shearing force is applied to the bolt 70 that joins the piece 22 of the ring 14, and these bolts 64, 70 do not break.

  When constructing the lining 12, as shown in FIG. 1, the formwork 16 is arranged in the tunnel 10 with an interval inward from the ground 20, and concrete is placed between the formwork and the ground 20. Set up. A twill plate 80 is disposed between the shield 18 for excavating the tunnel 10 and the mold 16. The end plate 80 is attached to the shield 18.

  A plurality of jacks 82 are disposed in the shield 18 at intervals in the circumferential direction. Each jack 82 has one end attached to the shield 18 and the other end directed to the mold 16. While placing concrete between the mold 16 and the ground 20, the jack 82 is extended to take a reaction force on the mold 16 and propel the shield 18.

  After the concrete between the ring 14a closest to the wellhead of the tunnel 10 and the ground 20 is hardened, the ring 14a nearest to the wellhead is dismantled. When disassembling the ring 14a closest to the wellhead, first, the disassembly piece 24 of the ring 14a closest to the wellhead is removed from between two adjacent pieces 44, and then the pieces 22 other than the disassembly piece 24 are removed. To do.

  When removing the dismantling piece 24 from between two adjacent pieces 44, first, the disassembly piece 24 and the adjacent piece 44 are joined together, and the disassembly piece 24 and the piece 22 of the other ring 14 are joined. Release the bond. Next, as shown in FIG. 5, by rotating the bolt 76 of the spacing maintaining means 72 relative to the nut 78 and moving the bolt 76 in the radial direction, the bottom wall portion 60b of the frame body 60 of the adjacent piece 44 is obtained. The projecting amount of the bolt 76 from is reduced. Thereafter, as shown in FIGS. 6 and 7, the dismantling piece 24 is moved toward the center of the tunnel 10 by using an erector (not shown) and pulled away from the concrete. After that, as shown in FIG. 8, the dismantling piece 24 is moved from the face side toward the wellhead side using the erector, and is removed from between the two pieces 44 adjacent to the dismantling piece 24.

  If the dismantling piece 24 is moved in the axial direction and pulled away from the concrete, a frictional force acts between the dismantling piece 24 and the concrete, so that the disassembling piece 24 is pulled away from the concrete. A very large force is required, and it becomes difficult to separate the dismantling piece 24 from the concrete. For this reason, the dismantling piece 24 is not moved away from the concrete in the axial direction, but the dismantling piece 24 is moved away from the concrete in the radial direction.

  After disassembling the ring 14a closest to the wellhead, the jack 82 is shrunk, and the disassembled ring 14a is moved between the jack 82 and the ring 14b closest to the face of the tunnel 10. Thereafter, the moved ring 14a is assembled to form a new ring (not shown) adjacent to the ring 14b closest to the face.

  When forming the new ring, first, the pieces 22 other than the assembly pieces 26 are arranged adjacent to each other in the circumferential direction, and finally, between the two pieces 22 that define a space in which the assembly pieces 26 are arranged. The assembly piece 26 is inserted into the assembly. Since the circumferential length of the assembly piece 26 gradually increases from the wellhead side to the face side, the assembly piece 26 can be moved from the face side to the wellhead side and inserted between the two pieces 22.

  After the formation of the new ring, concrete between the new ring and the ground 20 is placed. In this way, the lining 12 is constructed from the wellhead side to the face side.

  In the example shown in FIG. 9, the spacing maintaining means 72 includes a bolt 76 that penetrates the bottom wall portion 60b of the frame body 60 of the adjacent piece 44, and a nut 78 that is screwed to the bolt and fixed to the bottom wall portion 60b. 3 instead of the spacer 84 inserted through the first side wall portion 60a of the frame body 60 and between the bottom portion 38 of the dismantling piece 24 and the bottom portion 54 of the adjacent piece 44. Become.

  In the illustrated example, a plurality of spacers 84 are arranged at intervals in the axial direction. Each spacer 84 is plate-shaped and has a wedge-shaped side surface shape. That is, the thickness of the spacer 84 gradually decreases from the one end portion 84a toward the other end portion 84b. A through hole 86 is provided in the first side wall portion 60a of the frame body 60 of the dismantling piece 24, and the spacer 84 is adjacent to the bottom portion 38 of the disassembling piece 24 through the through hole 86 and from the other end 84b first. Between the bottom portion 54 and the bottom portion 54. Each spacer 84 may have a rod shape instead of the illustrated example having a plate shape.

  The spacer 84 is pulled out from between the bottom portion 38 of the disassembling piece 24 and the bottom portion 54 of the adjacent piece 44 when the ring 14a is disassembled, and is again removed when the new ring is assembled. It is inserted between the bottom portion 38 and the bottom portion 54 of the adjacent piece 44. Since the thickness of the spacer 84 gradually decreases from the one end portion 84a toward the other end portion 84b, it is relatively easy from between the bottom portion 38 of the disassembly piece 24 and the bottom portion 54 of the adjacent piece 44 when the ring 14a is disassembled. Can be pulled out.

  In the example shown in FIGS. 10 and 11, the gap maintaining means 72 is inserted between the bottom portion 38 of the dismantling piece 24 and the bottom portion 54 of the adjacent piece 44 through the first side wall portion 60 a of the frame body 60. 9 consisting of a spacer 84, and a spacer 88 inserted between the bottom portion 38 of the dismantling piece 24 and the bottom portion 54 of the adjacent piece 44 from the wellhead side to the face side. .

  As shown in FIG. 11, the spacer 88 has an L-shaped side shape, and a vertical portion 90 disposed between the bottom portion 38 of the dismantling piece 24 and the bottom portion 54 of the adjacent piece 44, And a horizontal portion 92.

  In the example shown in FIG. 11, the disassembly piece 24 has a constant interval between the bottom portion 36 and the bottom portion 38, and the adjacent piece 44 has an interval between the bottom portion 52 and the bottom portion 54 on the wellhead side. It gradually increases from the (right side of the drawing) to the face side (left side of the drawing). For this reason, the distance between the bottom portion 38 of the dismantling piece 24 and the bottom portion 54 of the adjacent piece 44 gradually decreases from the wellhead side to the face side. The vertical portion 90 of the spacer 88 has a side shape that matches the shape of the space between the bottom portion 38 of the dismantling piece 24 and the bottom portion 54 of the adjacent piece 44. That is, the width of the vertical portion 90 of the spacer 88 gradually decreases from the horizontal portion 92 toward the end portion 90 a of the vertical portion 90.

  The side portion 46 of the adjacent piece 44 has an end portion 94 that is separated from the end on the wellhead side of the adjacent piece 44 toward the face side. The lateral portion 92 of the spacer 88 is in contact with the end portion 94 of the adjacent piece 44, and the width of the lateral portion 92 is substantially equal to the distance between the end portion 94 of the adjacent piece 44 and the end portion on the wellhead side. The length of the horizontal portion 92 of the spacer 88 is longer than the radial length of the end portion 94 of the adjacent piece 44, and the horizontal portion 92 of the spacer 88 protrudes downward from the bottom 52 of the adjacent piece 44.

  The spacer 88 is removed by being pulled out from between the bottom portion 38 of the disassembling piece 24 and the bottom portion 54 of the adjacent piece 44 when the ring 14a is disassembled. At this time, the spacer 88 is a piece adjacent to the bottom portion 38 of the dismantling piece 24 by applying a force toward the wellhead side to a portion protruding downward from the bottom 52 of the adjacent piece 44 of the lateral portion 92 of the spacer 88. It can be easily pulled out from between the bottom portion 54 of 44. Since the width of the vertical portion 90 of the spacer 88 gradually decreases from the horizontal portion 92 toward the end portion 90 a of the vertical portion 90, the spacer is located between the bottom portion 38 of the disassembling piece 24 and the bottom portion 54 of the adjacent piece 44. The extraction of 88 is relatively easy. When the new ring is assembled, the spacer 88 is again inserted between the bottom portion 38 of the dismantling piece 24 and the bottom portion 54 of the adjacent piece 44.

1 is a longitudinal sectional view of a mold according to a first embodiment of the present invention. The perspective view of a formwork when it sees from the wellhead side. Sectional drawing of the piece for dismantling in the line 3 of FIG. The perspective view of the piece for dismantling. Sectional drawing of the piece for disassembly when the volt | bolt of a space | interval maintenance means is moved. Sectional drawing of the piece for disassembly when the piece for disassembly is moved toward the center of a tunnel. The perspective view of the piece for dismantling when the piece for dismantling is moved toward the center of a tunnel. The perspective view of the piece for disassembly when the piece for disassembly is moved toward the wellhead side from the face side. Sectional drawing of the piece for disassembly based on 2nd Example of this invention. The front view of the piece for disassembly based on 3rd Example of this invention. Sectional drawing of the space | interval maintenance means in the line 11 of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Tunnel 12 Covering 14 Ring 16 Formwork 22 Piece 24 Disassembly piece 26 Assembly piece 28 One side part 30 Other side part 32 Overhang | projection part 34,50 Side part 36,52 Bottom part 38,54 Bottom part 40,60 Frame 40a, 60a 1st side wall part 40b, 60b Bottom wall part 42, 62 Plate 44 Adjacent piece 46 Side part 48 Receiving part 56, 58 Radial length 72 Spacing maintenance means 76 Bolt 78 Nut 84 Spacer 88 Spacer

Claims (6)

  The ring is composed of a plurality of rings adjacent in the axial direction of the tunnel, and each ring is a plurality of pieces adjacent in the circumferential direction of the tunnel, and the length in the circumferential direction gradually increases from the face side of the tunnel toward the wellhead side. A plurality of pieces including at least one dismantling piece that has a length between one side portion and the other side portion in the circumferential direction from the outer side in the radial direction of the tunnel. Each of the side portions has a projecting portion extending in the circumferential direction, and the projecting portion has a side portion spaced laterally from the side portion and a bottom portion of the dismantling piece in the radial direction. And a piece adjacent to the dismantling piece has a receiving part on its side for receiving the overhang of the dismantling piece, the receiving part comprising: Inwardly spaced from the side of the adjacent piece The radial length of the side portion defined by the side portion defined by the bottom portion and the bottom portion spaced radially outward from the bottom portion of the adjacent piece and defining the receiving portion of the adjacent piece. Is a formwork longer than the radial length of the side portion of the overhang portion of the dismantling piece.   The formwork of Claim 1 by which the space | interval maintenance means is arrange | positioned between the said bottom part which prescribes | regulates the said receiving part of the said adjacent piece and the said bottom part of the said overhang | projection part of the said demolition piece.   The adjacent piece includes a substantially rectangular frame that is open on both sides, and a plate that is fixed to one side of the frame, and a side portion of the frame extends from the plate in the radial direction. A side wall portion extending inward and a bottom wall portion extending laterally from the side wall portion, wherein the side portion and the bottom portion defining the receiving portion of the adjacent pieces are respectively the side walls of the frame body A bolt that penetrates the bottom wall portion, which is arranged from the bottom wall portion of the frame body toward the bottom portion of the overhang portion of the dismantling piece. And a nut screwed to the bolt and fixed to the bottom wall portion.   The adjacent piece includes a substantially rectangular frame that is open on both sides, and a plate that is fixed to one side of the frame, and a side portion of the frame extends from the plate in the radial direction. The side portion defining the receiving portion of the adjacent piece comprises the side wall portion of the frame, and the spacing maintaining means penetrates the side wall portion of the frame. The mold according to claim 2, comprising a spacer inserted between the bottom portion of the overhang portion of the dismantling piece and the bottom portion defining the receiving portion of the adjacent piece.   The interval maintaining means is inserted between the bottom portion of the overhang portion of the dismantling piece and the bottom portion defining the receiving portion of the adjacent piece from the wellhead side toward the face side. The mold according to claim 2, comprising a spacer.   2. The formwork according to claim 1, wherein the plurality of pieces includes an assembly piece whose length in the circumferential direction gradually increases from the pit side toward the face side.

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