Composite segment and soil retainer structure

Abstract

To provide a composite segment and a soil retainer structure which can resist a tensile force caused in the axial direction of a tunnel and can reduce cost.SOLUTION: A composite segment is a component of a cylindrical body buried as a soil retainer structure, comprising: a pair of girders that extend in the circumference direction of the cylindrical body, being arranged with their plane surfaces facing each other in the axis direction of the cylindrical body; a pair of joint plates that are connected to both circumference ends of the pair of the girders; a skin plate that is arranged on a frame body constituted with the pair of girders and the pair of joint plates, being connected to the outer peripheral side in the radial direction of the cylindrical body; and at least one or more of securing member that is arranged on the inner surface of each of the pair of the girders, protruding from one girder towards the other, being fixed in the concrete filled inside the frame body and the skin plate, to compose a part for resisting the tensile force that acts on the pair of girders to be pulled away from each other.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a synthetic segment for forming an earth retaining structure buried in the ground and an earth retaining structure.

Background Art

[0002] Conventionally, synthetic segments for forming earth retaining structures such as tunnels are known. A synthetic segment is formed by arranging a reinforcing cage inside a steel shell having a main girder forming an axial end face of the earth retaining structure, a joint plate forming a circumferential end face, and a skin plate forming an outer peripheral face, and filling it with a filler such as concrete. Since the synthetic segment integrally forms the steel shell and the filler to ensure strength and rigidity, it can resist the earth pressure from the surrounding ground.

[0003] One of the tunnel construction methods is the shield method. The shield method is a method of constructing a shield tunnel in which, every time a shield machine installed in a shaft is advanced by a certain length, an arc-shaped synthetic segment is assembled in a ring shape at the rear to construct a segment ring, and this is sequentially extended to form a cylindrical lining. In the shield method, the shield machine is advanced using the segment ring as a reaction force receiver to construct a tunnel.

[0004] When constructing a curved portion of a tunnel, the shield machine needs to gradually change the propulsion direction by applying a rotational force to the shield by pushing the outer side of the curved portion of the tunnel with a propulsion jack. Therefore, in the curved portion of the tunnel, an eccentric force is generated with respect to the tunnel cross-section because the tunnel is pushed unidirectionally by the propulsion jack. Along with this, a relatively large tensile force acts in the axial direction of the tunnel at a part inside the curved portion of the tunnel in reaction to the unidirectional push of the propulsion jack. To resist the tensile force, the synthetic segment is provided with plate-like members made of steel plates called a plurality of vertical ribs that connect the opposing main girders inside the steel shell (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005] Patent Document 1 Japanese Patent Application Laid-Open No. 2020-63613 Summary of the Invention Problems to be Solved by the Invention

[0006] In the synthetic segment disclosed in Patent Document 1, the vertical ribs are formed of rectangular plate-shaped steel materials (steel plates) and are arranged substantially perpendicular to the main girders between the main girders. The synthetic segment of Patent Document 1 uses a plurality of vertical ribs arranged at predetermined intervals, and there is a problem that the amount of steel plate used is large and the cost is high.

[0007] The present disclosure solves the above problems, and can resist tensile forces in the axial direction of the tunnel, and can reduce the amount of steel plate used and the cost as compared with the case of using vertical ribs, and aims to provide a synthetic segment and an earth retaining structure. Means for Solving the Problems

[0008] The synthetic segment according to the present disclosure is a synthetic segment that constitutes a cylindrical body buried as an earth retaining structure, and includes a pair of main girders that extend in the circumferential direction of the cylindrical body and are arranged with their plate surfaces facing each other in the axial direction of the cylindrical body, a pair of joint plates joined to both circumferential ends of each of the pair of main girders, a skin plate joined to the outer peripheral side in the radial direction of the cylindrical body with respect to a frame body constituted by the pair of main girders and the pair of joint plates, and at least one or more fixing members provided so as to protrude from one main girder toward the other main girder on the inner surfaces of the pair of main girders, and fixed to the concrete filled inside the frame body and the skin plate, and configured to resist the tensile force applied to the pair of main girders in the direction in which the pair of main girders move away from each other.

[0009] The earth retaining structure of the present disclosure is formed by combining a plurality of the above synthetic segments in the circumferential direction and the axial direction.

Advantages of the Invention

[0010] The composite segment of the present disclosure includes at least one or more fixing members provided so as to protrude from one main girder toward the other main girder on the inner surfaces of a pair of main girders. The fixing members are fixed to the concrete filled inside the frame body and the skin plate constituted by the pair of main girders and the pair of joint plates, and constitute a portion that resists the tensile force applied to the pair of main girders in the direction in which the pair of main girders move apart. The composite segment has a stronger bonding force with the concrete due to the fixing members and can resist the tensile force in the axial direction of the tunnel. In addition, since the composite segment does not use vertical ribs that are plate-shaped members of steel plates for resisting the tensile force applied to the main girders, the amount of steel plates used can be reduced and the cost can be reduced as compared with the case of using vertical ribs.

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0012] Hereinafter, the composite segment and the earth retaining structure according to the embodiments will be described with reference to the drawings and the like. In the following drawings including FIG. 1, the relative dimensional relationships and shapes of the respective components may be different from the actual ones. Also, in the following drawings, those with the same reference numerals are the same or corresponding thereto, and this shall be common throughout the entire text of the specification. In addition, terms indicating directions (for example, up, down, left, right, front, back, front and back, etc.) are appropriately used for ease of understanding, but their notations are for the convenience of explanation and do not limit the arrangement, direction, and orientation of the device, instrument, or component, etc.

[0013] Embodiment 1. [Earth retaining structure 200] FIG. 1 is a conceptual diagram of the earth retaining structure 200 according to Embodiment 1. Note that the axial direction AD shown in FIG. 1 represents the axial direction of the earth retaining structure 200, the circumferential direction CD represents the circumferential direction of the earth retaining structure 200, the radial direction RD represents the radial direction of the earth retaining structure 200, the Y1 side represents the inner circumferential side of the earth retaining structure 200, and the Y2 side represents the outer circumferential side of the earth retaining structure 200. Also, in the description of the following various members, the description that they extend along various directions such as the axial direction AD, the circumferential direction CD, or the radial direction RD only needs to extend generally along that direction and does not have to be strictly along that direction.

[0014] The earth retaining structure 200 is used, for example, as an earth retaining wall for the lining of a tunnel and is installed on the wall surface of an excavation hole formed by excavating the natural ground. The earth retaining structure 200 is installed underground and is used as an earth retaining wall for tunnels that constitute subways, road tunnels, sewers, power and communication ducts, utility tunnels, etc., or for shafts, etc. Further, the earth retaining structure 200 may be used as an earth retaining wall for other construction methods such as the pressed-in caisson method.

[0015] When the earth retaining structure 200 is used as an earth retaining wall for the shield method, the earth retaining structure 200 covers the underground excavation surface in a construction method such as the shield method and is installed in the ground 90. When the earth retaining structure 200 is used as an earth retaining wall for the pressed-in caisson method, the earth retaining structure 200 covers the underground excavation surface in a construction method such as the pressing-in method and is sunk into the ground 90.

[0016] The earth retaining structure 200 is formed in a cylindrical shape and has a hollow portion 91. When the earth retaining structure 200 is used as an earth retaining wall for the shield method, the earth retaining structure 200 is arranged, for example, so as to extend in the advancing direction of the shield machine, that is, so that the cylindrical axial direction AD extends horizontally in the ground or in a state inclined with respect to the horizontal direction. When the earth retaining structure 200 is used as an earth retaining wall for the pressed-in caisson method, the earth retaining structure 200 is arranged, for example, so that the cylindrical axial direction AD is in the vertical direction in the ground.

[0017] The earth retaining structure 200 is formed in a circular shape when viewed in the axial direction AD and is formed in a cylindrical shape as a whole, but is not limited to the cylindrical shape. As long as the earth retaining structure 200 is a cylindrical body, it may be formed in other shapes such as an oval shape, a oval-shaped coin shape, or a square shape with rounded corners when viewed in the axial direction AD.

[0018] The earth retaining structure 200 has at least one segment ring 150, or has a plurality of segment rings 150, and the plurality of segment rings 150 are formed by being continuously connected in the axial direction AD in which the tunnel extends. The earth retaining structure 200 is formed by combining a plurality of synthetic segments 100, which will be described later, in the circumferential direction CD and the axial direction AD.

[0019] [Segment Ring 150] FIG. 2 is a conceptual diagram of the segment ring 150 according to Embodiment 1 as viewed in the axial direction AD. The segment ring 150 is a structure that covers the excavation surface in the ground. The segment ring 150 is formed in an annular shape when viewed in the axial direction AD, and is formed as a cylindrical body as a whole. The segment ring 150 is formed, for example, in a cylindrical shape, but is not limited to the cylindrical shape. As long as the segment ring 150 is a cylindrical body, it may be formed in other shapes, for example, an oval shape, a oval coin shape, or a square shape with rounded corners when viewed in the axial direction AD.

[0020] The earth retaining structure 200 is constructed by connecting a plurality of segment rings 150 in the direction in which the earth retaining structure 200 extends, that is, along the axial direction AD as shown in FIG. 1, by the connecting portion 93. Note that the earth retaining structure 200 may be constituted by one segment ring 150. When the earth retaining structure 200 is used, for example, in the shield method, the earth retaining structure 200 is constructed by arranging the segment rings 150 one by one for one circumference (one ring) of the cross section of the tunnel. Therefore, the segment ring 150 constitutes one unit in the direction in which the tunnel extends in the earth retaining structure 200.

[0021] The segment ring 150 is divided into a plurality of composite segments 100 in the circumferential direction CD. That is, as shown in FIGS. 1 and 2, a plurality of composite segments 100 are arranged in a ring shape, and the adjacent composite segments 100 are connected to each other at the connecting portion 92 to form the segment ring 150. Note that although the segment ring 150 shown in FIG. 2 is described as having substantially equal sizes of the composite segments 100 in the circumferential direction CD, the sizes of the composite segments 100 may be formed in different sizes and shapes depending on the installation positions in the circumferential direction CD.

[0022] As shown in FIG. 1, in the earth retaining structure 200, the segment rings 150 adjacent to each other in the axial direction AD are assembled in a state where the positions of the composite segments 100 constituting the segment rings 150 are shifted in the circumferential direction CD. For example, in the earth retaining structure 200, the composite segments 100 constituting the segment rings 150 are constructed in a staggered relationship. Note that the arrangement of the composite segments 100 is not limited to the staggered arrangement.

[0023] [Composite segment 100] FIG. 3 is a perspective view of an example of the composite segment 100 according to Embodiment 1 as viewed from the inner circumferential side. FIG. 4 is a perspective view of an example of the composite segment 100 according to Embodiment 1 as viewed from the outer circumferential side. FIG. 5 is a plan view showing an example of the internal structure of the composite segment 100 according to Embodiment 1. FIG. 6 is a side view showing an example of the internal structure of the composite segment 100 according to Embodiment 1. FIG. 7 is a schematic cross-sectional view showing an example of the internal structure of the composite segment 100 according to Embodiment 1. Note that in order to explain the internal structure of the composite segment 100, in FIG. 3, the illustration of the concrete 80 is partially omitted, and in FIGS. 5 to 7, the illustration of all the concrete 80 is omitted. FIGS. 3 and 4 are illustrated with the top and bottom reversed. FIG. 7 is a schematic cross-sectional view taken along the line A-A in FIG. 6. The composite segment 100 will be described with reference to FIGS. 3 to 7.

[0024] The synthetic segment 100 constitutes a cylindrical body to be embedded as an earth retaining structure. The synthetic segment 100 constitutes a segment ring 150 formed in a cylindrical shape that covers the underground excavation surface by being arranged annularly and connected to each other in the circumferential direction CD. The synthetic segment 100 constructs the earth retaining structure 200 by being connected in a plurality in the circumferential direction CD and the axial direction AD of the earth retaining structure 200. The synthetic segment 100 has a box-shaped structure composed of a combination of a plurality of steel materials. The synthetic segment 100 is formed in an arc shape when viewed in the axial direction AD of the segment ring 150, and is formed in a curved shape as a whole. One synthetic segment 100 may also be referred to as a piece.

[0025] The synthetic segment 100 has a steel shell 10 and concrete 80 filled inside the steel shell 10. The synthetic segment 100 has a composite structure of a box-shaped steel shell 10 and concrete 80 filled as a filler inside the steel shell 10, and the steel shell 10 and the concrete 80 are integrally formed.

[0026] [Reinforcement unit 40] As shown in FIG. 3, the synthetic segment 100 includes a reinforcement unit 40 in the concrete 80. The reinforcement unit 40 is arranged between a pair of main girders 11. The reinforcement unit 40 is composed of a reinforcing cage 41 and a first force-bearing reinforcement 48. In Embodiment 1, the reinforcing cage 41 and the first force-bearing reinforcement 48 are joined, and are integrated by being tied together using, for example, welding or wire binding. The reinforcement unit 40 is not limited to this configuration, and the reinforcing cage 41 and the first force-bearing reinforcement 48 do not have to be joined.

[0027] As shown in FIG. 7, the steel bar cage 41 is formed by joining a first main reinforcement bar 42, a second main reinforcement bar 43, and a second stirrup 45. The first main reinforcement bar 42 extends in the circumferential direction CD, and a plurality of them are arranged at intervals in the axial direction AD. Further, the second main reinforcement bar 43 is arranged at an interval from the first main reinforcement bar 42 in the radial direction RD. The second main reinforcement bar 43 also extends in the circumferential direction CD like the first main reinforcement bar 42, and a plurality of them are arranged at intervals in the axial direction AD. Note that the number of the first main reinforcement bar 42 and the second main reinforcement bar 43 is not limited to a plurality, and may be a single number.

[0028] As shown in FIGS. 6 and 7, the steel bar cage 41 includes two rows of main reinforcement bars, a first main reinforcement bar 42 arranged on the inner peripheral side and a second main reinforcement bar 43 arranged on the outer peripheral side, in the radial direction RD. However, the steel bar cage 41 is not limited to such a configuration, and may include a single row of main reinforcement bars in the radial direction RD, or may include three or more rows of main reinforcement bars.

[0029] As shown in FIGS. 3 and 5, a plurality of second stirrups 45 are arranged along the longitudinal direction, that is, the circumferential direction CD, of the first main reinforcement bar 42 and the second main reinforcement bar 43. As shown in FIG. 7, the second stirrup 45 has a main body portion 45a extending along the axial direction AD, an arm portion 45b formed by bending an end portion of the main body portion 45a in the radial direction RD, and a tip portion 45c formed by bending the tip of the arm portion 45b in the axial direction AD.

[0030] The second stirrup 45 is formed in a U-shape or a shape in which a part of the U-shape is cut out so as to surround the rows of the first main reinforcement bar 42 and the second main reinforcement bar 43 from the outside. The second stirrup 45 may be arranged on the inner peripheral side of the first main reinforcement bar 42 in the radial direction RD as shown in FIGS. 3 and 5, or may be arranged on the outer peripheral side of the second main reinforcement bar 43 as shown in FIGS. 5 and 7.

[0031] The second force - distributing reinforcement 45 is a reinforcing bar, which may be formed by bending a single bar or by combining a plurality of bars. The second force - distributing reinforcement 45 forms an integral reinforcing - bar cage 41 by connecting between a plurality of first main reinforcements 42 and second main reinforcements 43 arranged in parallel. The second force - distributing reinforcement 45 may transmit the load applied to the first main reinforcement 42 and the second main reinforcement 43 to the adjacent first main reinforcement 42 and second main reinforcement 43 and disperse the load. Note that the number of the second force - distributing reinforcements 45 is not limited to a plurality and may be a single one.

[0032] The reinforcing - bar unit 40 includes a first force - distributing reinforcement 48 extending in the axial direction AD. Both ends of the first force - distributing reinforcement 48 are fixed to the fixing member 20. The first force - distributing reinforcement 48, together with the fixing member 20 described later, is a member that resists the tensile force applied to the main girder 11 in the axial direction AD and reduces and eliminates the tensile force applied to the main girder 11. As shown in FIG. 5, the first force - distributing reinforcement 48 is arranged in parallel with the second force - distributing reinforcement 45 in the radial direction RD.

[0033] The first force - distributing reinforcement 48 is arranged adjacent to the second force - distributing reinforcement 45 and is combined with the second force - distributing reinforcement 45 having a shape with a part of a square - bracket shape cut out, and is formed to surround the first main reinforcement 42 and the second main reinforcement 43 as shown in FIG. 7. However, the first force - distributing reinforcement 48 may be arranged at an interval from the second force - distributing reinforcement 45 in the radial direction RD. Also, the first force - distributing reinforcement 48 may be arranged at an interval from the second force - distributing reinforcement 45 in the circumferential direction CD.

[0034] The first force - distributing reinforcement 48 is a reinforcing bar, which may be formed by bending a single bar or by combining a plurality of bars. The first force - distributing reinforcement 48 includes a main body portion 48b extending along the axial direction AD and insertion portions 48a extending in the radial direction RD from both ends of the main body portion 48b as shown in FIG. 7. That is, the first force - distributing reinforcement 48 is formed in a U - shape. Both end portions of the main body portion 48b are placed on the fixing member 20 described later, and the insertion portions 48a are inserted into the first through - holes 25 provided in the fixing member 20 described later. The main body portion 48b of the first force - distributing reinforcement 48 is arranged adjacent to the first main reinforcement 42 of the reinforcing - bar cage 41.

[0035] [Steel shell 10] As shown in FIGS. 3 and 4, the steel shell 10 of the composite segment 100 is provided at a distance in the axial direction AD, and has a pair of arc-shaped main girders 11 arranged with their plate surfaces facing each other, and a pair of joint plates 12 joined to both ends of the main girder 11 in the circumferential direction CD. Further, the steel shell 10 has a skin plate 16 joined to the outer peripheral side of the main girder 11 and the joint plate 12. The steel shell 10 is formed in a box shape by welding these main girders 11, joint plates 12, and skin plates 16 to each other. The steel shell 10 of the composite segment 100 does not have so-called vertical ribs, which are plate-shaped members of steel plates for connecting a pair of main girders 11 to each other and resisting the tensile force applied to the main girder 11.

[0036] The pair of main girders 11 extend in the circumferential direction CD of the earth retaining structure 200 or the segment ring 150, which is a cylindrical body, and are arranged with their plate surfaces facing each other in the axial direction AD of the cylindrical body. The pair of main girders 11 are portions where adjacent composite segments 100 abut against each other and where adjacent composite segments 100 are connected to each other in the axial direction AD of the earth retaining structure 200 and the segment ring 150.

[0037] The pair of main girders 11 are located at both ends of the composite segment 100 in the axial direction AD of the earth retaining structure 200 and the segment ring 150. That is, the main girder 11 is provided at both ends of the skin plate 16 in the axial direction AD of the earth retaining structure 200 and the segment ring 150, and forms one end surface and the other end surface of the composite segment 100 in the axial direction AD.

[0038] As shown in FIG. 5, the main girder 11 is formed in a flat plate shape. As shown in FIG. 6, the main girder 11 is formed in an arc shape in a plan view seen in the axial direction AD according to the cross-sectional shape of the tunnel, and is formed in a fan shape that constitutes a part of the segment ring 150, which is an annular body. The plate surface of the main girder 11 extends in the circumferential direction CD and the radial direction RD and is parallel to the circumferential direction CD and the radial direction RD.

[0039] As shown in FIG. 3, among a pair of main girders 11, a plurality of bolt holes 13 are formed in one of the main girders 11 for connecting adjacent synthetic segments 100 connected in the axial direction AD before and after. The number of bolt holes 13 is not limited to a plurality and may be a single number. The bolt holes 13 are formed one by one in the central region and both end regions in the circumferential direction CD where the fixing member 20 is not arranged as an example.

[0040] As shown in FIG. 3, in the synthetic segment 100, a bolt box 81 is provided at a location corresponding to the bolt hole 13 in the concrete 80. The bolt box 81 forms a space in the synthetic segment 100 to expose the bolt hole 13 between the concrete 80 and the main girder 11. The bolt box 81 serves as a working space for fastening bolts for fastening the main girders 11 of adjacent synthetic segments 100 in the axial direction AD.

[0041] As shown in FIGS. 3 and 4, among a pair of main girders 11, a plurality of bosses 14 are formed in the other main girder 11 for connecting adjacent synthetic segments 100 connected in the axial direction AD before and after. The number of bosses 14 is not limited to a plurality and may be a single number. An attachment hole having an internal thread for screwing a bolt is formed in the boss 14.

[0042] Two adjacent synthetic segments 100 in the axial direction AD butt the main girders 11 against each other and are joined by bolts. The joining utilizes the bolt box 81, inserts the bolts into the bolt holes 13, and screws them into the internal threads of the bosses 14 provided on the main girders 11 of the adjacent synthetic segments 100. By screwing and fastening the shaft portions of the bolts inserted into the bolt holes 13 into the internal threads of the bosses 14, the two adjacent synthetic segments 100 in the axial direction AD are connected.

[0043] The number of bolt holes 13 and bosses 14 formed is not limited to the illustrated embodiment, and is determined in consideration of, for example, the size and shape of the composite segment 100. In addition, the connection between adjacent composite segments 100 in the axial direction AD is not limited to a structure connected by bolts and nuts. For example, it may be performed by a one-touch joint, or other well-known techniques may also be used.

[0044] The pair of joint plates 12 are portions where adjacent composite segments 100 abut and are connected to each other in the circumferential direction CD of the earth retaining structure 200 and the segment ring 150. The pair of joint plates 12 are members attached to both ends of the composite segment 100 in the circumferential direction CD.

[0045] The joint plate 12 is formed in a plate shape and is made of a rectangular steel plate. The joint plate 12 is formed so as to extend in the axial direction AD and the radial direction RD. The joint plate 12 is spanned and fixed between both longitudinal ends of the pair of main girders 11. Note that the longitudinal direction of the main girder 11 is the circumferential direction CD. A joint for connecting the composite segments 100 to form one segment ring 150 may be attached to the end of the composite segment 100 where the joint plate 12 is located.

[0046] The pair of joint plates 12 are joined to both ends of each of the pair of main girders 11 in the circumferential direction CD. The joint plate 12 is disposed so as to cover an opening formed by the pair of main girders 11 and the skin plate 16 disposed between the pair of main girders 11 at both ends of the composite segment 100 in the circumferential direction CD. The joint plate 12 is provided at both ends of the skin plate 16 in the arc direction to form the side surface of the composite segment 100 in the circumferential direction CD.

[0047] As shown in Fig. 3, a plurality of bolt holes 15 are formed in the joint plate 12 for connecting the synthetic segments 100 adjacent to each other on the left and right in the circumferential direction CD of the excavation hole. The number and formation positions of the bolt holes 15 shown in Figs. 3 to 5 are examples and are not limited to the illustrated embodiments. The number and formation positions of the bolt holes 15 are determined in consideration of, for example, the size and shape of the synthetic segment 100 and the like.

[0048] The number of the bolt holes 15 is not limited to a plurality and may be a single number. That is, the bolt hole 15 may be provided at one location or a plurality of locations in the axial direction AD. Further, the position of the bolt hole 15 is not limited to both end positions in the axial direction AD as shown in Figs. 3 to 5, and may be provided closer to the center side in the axial direction AD than the illustrated embodiments.

[0049] As shown in Fig. 3, in the synthetic segment 100, a bolt box 82 is provided at a location corresponding to the bolt hole 15 in the concrete 80. The bolt box 82 forms a space for exposing the bolt hole 15 between the concrete 80 and the joint plate 12 in the synthetic segment 100. The bolt box 82 serves as a working space for fastening bolts for fastening the joint plates 12 of adjacent synthetic segments 100 in the circumferential direction CD.

[0050] The synthetic segments 100 adjacent to each other on the left and right in the circumferential direction CD are connected by butting the joint plates 12 and fastening the shaft portions of the bolts inserted through the bolt holes 15 with nuts. Note that the connection between the synthetic segments 100 adjacent to each other in the circumferential direction CD is not limited to a structure connected by bolts and nuts. For example, it may be performed by a one-touch joint, or other well-known techniques may also be used.

[0051] The skin plate 16 is a plate-like member facing the base side of the synthetic segment 100, and is formed by bending a rectangular steel plate into an arc shape in the plane direction. The skin plate 16 is formed in a plate shape having a curved surface. The skin plate 16 is formed so as to extend in the circumferential direction CD and the axial direction AD. The skin plate 16 is formed in an arc shape in a plan view seen in the axial direction AD, and is formed in a rectangular shape in a side view seen in the radial direction RD.

[0052] As shown in FIG. 5, the skin plate 16 is joined so as to close the opening at the end face on the base side of the frame obtained by joining a pair of main girders 11 and a pair of joint plates 12. That is, the skin plate 16 is joined to the outside in the radial direction RD of the cylindrical body with respect to the frame constituted by the pair of main girders 11 and the pair of joint plates 12. The skin plate 16 faces the wall surface of the excavation hole in a state where the synthetic segment 100 is installed in the ground, and constitutes the peripheral wall on the outer peripheral side of the earth retaining structure 200.

[0053] [Fixing member 20] As shown in FIG. 3, the steel shell 10 includes at least one or more fixing members 20 that project inward from the pair of main girders 11. The fixing member 20 is fixed and integrated with the concrete 80 and functions as a so-called anchor. The fixing member 20 is provided so as to project from one main girder 11 toward the other main girder 11 on the inner surface of the pair of main girders 11. The fixing member 20 is fixed to the concrete 80 filled inside the frame and the skin plate 16 constituted by the pair of main girders 11 and the pair of joint plates 12, and constitutes a portion that resists the tensile force applied to the pair of main girders 11 so as to move in a direction in which the pair of main girders 11 move apart.

[0054] The fixing member 20 is provided on the inner surface of the main girder 11 and is welded to the inner surface of the main girder 11. The fixing member 20 protrudes from one of the main girders 11 inside one of the main girders 11 and is not connected to the other main girder 11. That is, the tip of the fixing member 20 in the protruding direction is fixed to the concrete 80 and is not connected to the other main girder 11. The fixing member 20 protrudes from the steel shell 10 toward the inside of the concrete 80 in the composite segment 100 and is combined with the concrete 80. The fixing member 20 is a member that resists the tensile force applied to the main girder 11 in the axial direction AD and reduces and eliminates the tensile force applied to the main girder 11. Further, the fixing member 20, together with the first force reinforcing bar 48, is a member that resists the tensile force applied to the main girder 11 in the axial direction AD, reduces the tensile force applied to the main girder 11, and eliminates it.

[0055] The fixing members 20 are provided at positions facing each other in the axial direction AD on each of the pair of main girders 11. In one of the main girders 11 of the steel shell 10 according to the first embodiment, the fixing members 20 are arranged at six positions along the circumferential direction CD. The number and positions of the fixing members 20 are not limited to the illustrated mode, and are determined in consideration of, for example, the size and shape of the composite segment 100.

[0056] FIG. 8 is a perspective view and a plan view of the fixing member 20 of the composite segment 100 according to the first embodiment. FIG. 8(a) is a perspective view of the fixing member 20 viewed from the inside in the radial direction RD. FIG. 8(b) is a plan view of the fixing member 20 viewed in the axial direction AD. FIG. 8(c) is a perspective view of a modified example of the fixing member 20 viewed from the inside in the radial direction RD. The fixing member 20 includes a first portion 21 that is a plate-like portion arranged along the circumferential direction CD, and a second portion 22 that is a plate-like portion arranged along the radial direction RD. In FIG. 8, the second portion 22 is provided on the right side of the first portion 21, but the second portion 22 may be provided on the left side of the first portion 21.

[0057] The first part 21 is arranged such that the plate surface extends in the circumferential direction CD and the axial direction AD, and the second part 22 is arranged such that the plate surface extends in the radial direction RD and the axial direction AD. In Embodiment 1, the fixing member 20 is an angle formed integrally with the plate surfaces of the first part 21 and the second part 22 being orthogonal to each other, and is a channel steel. The fixing member 20 may be formed by welding together the first part 21 and the second part 22 each formed from a separate plate material. Further, the fixing member 20 may be formed by bending a single steel plate into an L shape.

[0058] The second part 22 of the fixing member 20 along the radial direction RD holds the wedge-shaped (sector-shaped) concrete 80 between the second parts 22 adjacent in the circumferential direction CD, thereby suppressing the displacement between the concrete 80 and the steel shell 10. Further, the fixing member 20 suppresses the displacement or protrusion of the concrete 80 in the radial direction RD by the first part 21 extending along the circumferential direction CD.

[0059] Since the first part 21 and the second part 22 are integrated and the fixing member 20 has high rigidity and high bonding strength with the main girder 11, the effect of suppressing the displacement between the concrete 80 and the steel shell 10 is improved. By having the fixing member 20, the composite segment 100 strengthens the integration between the concrete 80 and the main girder 11 via the fixing member 20.

[0060] The first part 21 is formed such that the plate surface extends parallel to the tangential direction of the circumferential direction CD and the axial direction AD. As shown in FIG. 8(a), a first through-hole 25 is formed in the first part 21. The first part 21 serves as, for example, a PBL (Perfo-Bond Leisten). The first part 21 is provided at the inner diameter side end of the second part 22 extending along the radial direction RD.

[0061] FIG. 9 is an enlarged view of the fixing member 20 portion of the synthetic segment 100 according to Embodiment 1. As shown in FIGS. 8 and 9, the first through-hole 25 is a hole penetrating in the plate thickness direction and is a hole penetrating the first portion 21 in the radial direction RD. The number of the first through-holes 25 is not limited to a single number and may be plural. The first through-hole 25 is a circular hole, but the shape of the hole is not limited to a circular hole, and holes with other opening shapes may also be used. As shown in FIG. 9, an insertion portion 48a of the first force-bearing rib 48 is inserted into the first through-hole 25, and the end portion of the first force-bearing rib 48 is positioned inside the first through-hole 25.

[0062] The fixing member 20 is arranged so as to face each other in the axial direction AD between a pair of main girders 11 arranged with their plate surfaces facing each other. In the axial direction AD, one end portion of the first force-bearing rib 48 is connected to the first through-hole 25 of the fixing member 20 provided on one main girder 11, and the other end portion of the first force-bearing rib 48 is connected to the first through-hole 25 of the fixing member 20 provided on the other main girder 11. Both end portions of the first force-bearing rib 48 are respectively connected to the fixing member 20. Note that the end portion of the first force-bearing rib 48 and the fixing member 20 may be fixed by welding.

[0063] The first force-bearing rib 48 connects two fixing members 20 arranged to face each other in a state where the concrete 80 is filled. The first force-bearing rib 48 strengthens the integrality between one main girder 11 and the other main girder 11 in the axial direction AD and suppresses the deformation and movement of the main girder 11. In the synthetic segment 100, the separation between the main girder 11 and the concrete 80 is suppressed by the first force-bearing rib 48 connected to the main girder 11, and the concrete 80 and the main girder 11 are firmly fixed via the first force-bearing rib 48 and the fixing member 20. The synthetic segment 100 has improved strength against loads in the direction in which the space between the pair of main girders 11 opens as compared with the case where the first force-bearing rib 48 is not provided, due to the first force-bearing rib 48.

[0064] Similar to the first portion 21, at least one or more second through-holes 26 may be formed in the second portion 22, like the fixing member 20 of the modification shown in FIG. 8(c). The second portion 22 serves the same role as a PBL (Perfo-Bond Leisten) divel as the first portion 21.

[0065] The second through-hole 26 is a hole that penetrates in the plate thickness direction and is a hole that penetrates the second portion 22 in the circumferential direction CD. The number of the second through-holes 26 is not limited to a single one, and a plurality of them may be provided. The second through-hole 26 is a circular hole, but the shape of the hole is not limited to a circular hole, and holes with other opening shapes may also be used.

[0066] [Shape retaining member 23] FIG. 10 is a perspective view of the steel shell 10 of the composite segment 100 according to Embodiment 1. FIG. 10 shows a state in which the reinforcing bar unit 40 is not disposed inside the steel shell 10. As shown in FIG. 10, a shape retaining member 23 is joined to the inner surface of the skin plate 16. The shape retaining member 23 protrudes from the skin plate 16 in the radial direction RD.

[0067] The shape retaining member 23 is a member that suppresses the deformation of the skin plate 16 so as to bulge out when installed on the skin plate 16. The shape retaining member 23 is a plate-like member, the longitudinal direction thereof is arranged along the axial direction AD, and both ends in the longitudinal direction are arranged at intervals from a pair of main girders 11. The shape retaining member 23 can be easily installed between the pair of main girders 11 because the end faces 23a on both sides in the axial direction AD are arranged at a distance from the main girders 11. However, both ends of the shape retaining member 23 can also be joined to both or one of the pair of main girders 11.

[0068] [Modification example of the composite segment 100] FIG. 11 is a schematic cross-sectional view showing the internal structure of a modification example of the composite segment 100 according to Embodiment 1. The structure of the reinforcing bar unit 40 used in the composite segment 100 can be changed as appropriate. As an example, the reinforcing bar unit 40A shown in FIG. 11 has a shape in which the first force-bearing bars 48A extend linearly, and the ends thereof protrude from the reinforcing bar cage 41 in the axial direction AD and are placed on the first portion 21 of the fixing member 20. In this case, the first force-bearing bars 48A may be joined to the reinforcing bar cage 41 in advance.

[0069] Since the reinforcing bar unit 40A shown in Fig. 11 is not structured to insert the first force-bearing bar 48A into the first through-hole 25, it can be arranged without requiring highly accurate positioning with respect to the steel shell 10. Further, the reinforcing bar unit 40A can enhance the bonding force with the steel shell 10 by joining the first force-bearing bar 48A to the fixing member 20 by means such as welding.

[0070] Fig. 12 is a schematic cross-sectional view showing the internal structure of a modified example of the composite segment 100 according to Embodiment 1. The reinforcing bar unit 40 of the composite segment 100 can also omit the first force-bearing bar 48. Even in this case, the composite segment 100 can resist the tensile force applied to the main girder 11 as compared with the case where it does not have the fixing member 20 by the fixing member 20.

[0071] Fig. 13 is a schematic view showing the internal structure of a modified example of the steel shell 10 of the composite segment 100 according to Embodiment 1. As shown in Fig. 13, the steel shell 10 may not have the shape-retaining member 23.

[0072] [Manufacturing method of the composite segment 100] Next, the manufacturing method of the composite segment 100 will be described. First, a step of assembling the steel shell 10 is performed. As shown in Fig. 10, the steel shell 10 forms a frame body by joining a pair of main girders 11 and a pair of joint plates 12, and a skin plate 16 is arranged outside the frame body in the radial direction RD. The pair of main girders 11, the pair of joint plates 12, and the skin plate 16 are arranged on, for example, a jig and combined into the shape of the steel shell 10, and the members are joined by joining means such as welding.

[0073] After the pair of main girders 11, the pair of joint plates 12, and the skin plate 16 are combined, a step of installing the internal structure of the steel shell 10 is performed. For example, the members constituting the bolt box 82 for connecting the circumferential direction CD of the composite segment 100 are joined to the main girder 11, the joint plate 12, and the skin plate 16.

[0074] In the process of installing the internal structure of the steel shell 10, the step of joining the fixing member 20 to the main girder 11 is performed. Further, the step of joining the shape retaining member 23 to the skin plate 16 is performed. Note that the fixing member 20 may be joined to the main girder 11 in advance before combining the main girder 11 into the shape of the steel shell 10. Also, the shape retaining member 23 may be joined to the skin plate 16 in advance.

[0075] The shape retaining member 23 is installed in alignment with the fixing member 20 in the circumferential direction CD. Also, the shape retaining member 23 is set such that its longitudinal dimension is smaller than the width between the pair of main girders 11, and both end faces in the longitudinal direction are installed at a distance from the main girder 11. Through the above steps, the steel shell 10 is formed in the state shown in FIG. 10. Note that the shape retaining member 23 may not be provided.

[0076] FIG. 14 is a perspective view of a state in which the steel shell 10 shown in FIG. 10 houses the reinforcing cage 41. After the steel shell 10 is assembled, the steel shell 10 is moved to, for example, a factory where concrete 80 is placed. Then, the step of installing the reinforcing bar unit 40 inside the steel shell 10 is performed. First, among the reinforcing bar units 40, the reinforcing cage 41 is disposed between the opposing fixing members 20 of the steel shell 10.

[0077] The reinforcing cage 41 is placed on the shape retaining member 23 installed inside the steel shell 10. Thereby, the secondary main reinforcing bars 43 and the second force - distributing bars 45 of the reinforcing cage 41 are disposed at a distance from the skin plate 16. Thereby, the secondary main reinforcing bars 43 are disposed with an appropriate cover thickness inside the concrete 80 to be filled.

[0078] FIG. 15 is a perspective view of the steel shell 10 shown in FIG. 14 with the first force-reinforcing bars 48 arranged. The first force-reinforcing bars 48 are arranged after the reinforcing bar cage 41 is arranged at an appropriate position. The first force-reinforcing bars 48 are arranged in the first through-holes 25 of the fixing members 20 arranged oppositely in the pair of main girders 11 through the insertion portions 48a (see FIG. 7) at both ends. In FIG. 7, the end of the main body portion 48b of the first force-reinforcing bar 48 is placed on the upper surface of the first portion 21 of the fixing member 20, but the main body portion 48b may be placed on the reinforcing bar cage 41 and set so that there is a gap between the main body portion 48b and the first portion 21.

[0079] After the first force-reinforcing bars 48 are arranged, the first main reinforcing bars 42 of the reinforcing bar cage 41 and the first force-reinforcing bars 48 are joined. The joining is performed by welding or bundling with wire. The first force-reinforcing bars 48 and the reinforcing bar cage 41 may be joined in advance and installed in the steel shell 10 as a reinforcing bar unit 40. In the case of the structure in which the first force-reinforcing bars 48 are inserted into the first through-holes 25 of the fixing members 20, in order to pass all the insertion portions 48a of the plurality of first force-reinforcing bars 48 through the first through-holes 25, highly accurate alignment is required, and the work is difficult depending on the environment at the assembly site. Therefore, the operator can install the reinforcing bar unit 40 without performing difficult alignment work by first installing the reinforcing bar cage 41 in the steel shell 10 and then installing the first force-reinforcing bars 48 in another process.

[0080] FIG. 16 is a perspective view of the steel shell 10 shown in FIG. 15 filled with concrete 80. Note that a part of the concrete 80 is omitted to show the internal structure of the steel shell 10. After the reinforcing bar unit 40 is arranged inside the steel shell 10, the concrete 80 is filled. A formwork is installed on the opening side of the steel shell 10, and the concrete 80 is filled into the space formed by the steel shell 10 and the formwork through an injection port (not shown) installed at the central portion of the steel shell 10. After the concrete 80 solidifies, the formwork is removed, and the composite segment 100 is completed.

[0081] [Effect of the composite segment 100 according to Embodiment 1] The composite segment 100 includes at least one or more fixing members 20 provided so as to protrude from one main girder 11 toward the other main girder 11 on the inner surfaces of the pair of main girders 11. The fixing member 20 is fixed to the concrete 80 filled inside the frame body and the skin plate 16 constituted by the pair of main girders 11 and the pair of joint plates 12, and constitutes a portion that resists the tensile force applied to the pair of main girders 11 in the direction in which the pair of main girders 11 move apart. The composite segment 100 has a stronger bonding force with the concrete 80 due to the fixing member 20 and can resist the tensile force in the axial direction AD of the tunnel. Further, since the composite segment 100 does not use the vertical ribs that connect the pair of main girders 11, which are plate-shaped members of steel plates for resisting the tensile force applied to the main girders 11, the amount of steel plates used can be reduced and the cost can be reduced as compared with the case of using vertical ribs.

[0082] FIG. 17 is a conceptual diagram showing the relationship between the shield machine 300 and the soil retaining structure 200 in the curved section. As shown in FIG. 17, when constructing the curved portion of the soil retaining structure 200 such as a tunnel, the shield machine 300 needs to gradually change the propulsion direction by applying a rotational force to the shield by pushing the outside of the curved portion of the tunnel with the propulsion jack. Therefore, in the curved portion of the tunnel, an eccentric force is generated with respect to the tunnel cross section because the tunnel is pushed unidirectionally by the propulsion jack. Along with this, on the inner side of the curved portion of the tunnel, a relatively large tensile force acts in part in the axial direction AD of the tunnel in response to the reaction force of the unidirectional push of the propulsion jack.

[0083] The composite segment 100 has its bonding force with the concrete 80 strengthened by the fixing member 20 provided on the main girder 11, so that peeling from the concrete 80 is suppressed, and the concrete 80 and the main girder 11 are firmly fixed via the fixing member 20. Therefore, the composite segment 100 can, by means of the fixing member 20, resist the tensile force applied to the main girder 11 as compared with the case where the fixing member 20 is not provided. Further, since the composite segment 100 does not use the longitudinal ribs connecting the pair of main girders 11 which are plate-shaped members of steel plates for resisting the tensile force applied to the main girder 11, the amount of steel plates used can be reduced and the cost can be reduced as compared with the case where longitudinal ribs are used.

[0084] Further, the fixing member 20 includes a first portion 21 arranged such that the plate surface extends in the circumferential direction CD and the axial direction AD, and a second portion 22 arranged such that the plate surface extends in the radial direction RD and the axial direction AD. Due to this configuration, the composite segment 100 has a higher bonding force between the main girder 11 and the concrete 80, and the strength against the load in the direction in which the pair of main girders 11 open is improved as compared with the case where this configuration is not present.

[0085] Further, a first through hole 25 is formed in the first portion 21 of the fixing member 20. Since the concrete 80 in the first through hole 25 is three-dimensionally constrained in the composite segment 100, a large shear resistance can be obtained by the fixing member 20 having the first through hole 25, and a resistance to the tensile force applied to the main girder 11 can be obtained. The composite segment 100 can, by means of the fixing member 20 having the first through hole 25, further resist the tensile force applied to the main girder 11 as compared with the case where the first through hole 25 is not provided.

[0086] Further, the fixing member 20 has a second through hole 26 formed in the second portion 22. Since the concrete 80 in the second through hole 26 of the composite segment 100 is three-dimensionally constrained, the fixing member 20 having the second through hole 26 can obtain a large shear resistance and can obtain a resistance to the tensile force applied to the main girder 11. The composite segment 100 can further resist the tensile force applied to the main girder 11 as compared with the case where it does not have the second through hole 26 by the fixing member 20 having the second through hole 26.

[0087] Further, in the composite segment 100, the fixing member 20 is provided so as to be paired with each of the pair of main girders 11 at positions facing each other in the axial direction AD, and both ends of the first force reinforcing bar 48 are configured to be fixed to the fixing member 20. In the composite segment 100, a force such as a tensile force applied to the main girder 11 is transmitted to the first force reinforcing bar 48 via the fixing member 20.

[0088] Both ends of the first force reinforcing bar 48 are connected to the fixing member 20 provided on the main girder 11, and the tensile force applied to the main girder 11 is transmitted via the fixing member 20, generating a resistance to the tensile force applied to the main girder 11. The composite segment 100 has improved strength against tensile force, that is, a load in the direction in which the pair of main girders 11 open, as compared with the case where the first force reinforcing bar 48 is not provided, by the first force reinforcing bar 48.

[0089] When the composite segment 100 has the first force reinforcing bar 48, the strength against the load in the direction in which the pair of main girders 11 open is further improved by the combined action of the fixing member 20 and the first force reinforcing bar 48 as compared with the case where only one of these members is provided. That is, the composite segment 100 can further resist the tensile force applied to the main girder 11 as compared with the case where only one of these members is provided, by the fixing member 20 and the first force reinforcing bar 48.

[0090] Further, the fixing member 20 has a first through hole 25 formed in the first portion 21, and the first force transmitting rib 48 includes a main body portion 48b extending in the axial direction AD and insertion portions 48a extending in the radial direction RD from both ends of the main body portion 48b. The insertion portions 48a of the first force transmitting rib 48 are inserted into the first through hole 25.

[0091] Both ends of the first force transmitting rib 48 are connected to the fixing member 20 provided on the main girder 11, and the tensile force applied to the main girder 11 is transmitted through the fixing member 20, generating a resistance force against the tensile force applied to the main girder 11. The composite segment 100 is improved in strength against a load in a direction in which the space between the pair of main girders 11 opens as compared with the case where there is no first force transmitting rib 48, by the first force transmitting rib 48 inserted into the first through holes 25 provided in the first portions 21 of the two opposing fixing members 20. Further, since the first force transmitting rib 48 only needs to be inserted into the first through hole 25, positioning becomes easy, and the composite segment 100 is easier to assemble as compared with welding the first force transmitting rib 48 and the fixing member 20.

[0092] Embodiment 2. FIG. 18 is a partially enlarged view of the composite segment 100 according to Embodiment 2. FIG. 19 is a plan view and a side view of the fixing member 20A of the composite segment 100 according to Embodiment 2. FIG. 19(a) is a plan view of the fixing member 20A viewed in the axial direction AD. FIG. 19(b) is a side view of the fixing member 20A viewed in the radial direction RD. FIG. 19(c) is a side view of the fixing member 20A viewed in the circumferential direction CD. FIG. 19(d) is a side view of a modified example of the fixing member 20A viewed in the circumferential direction CD. For components having the same functions and operations as those of the composite segment 100 according to Embodiment 1, the same reference numerals are given and their descriptions are omitted. Hereinafter, with reference to FIGS. 18 and 19, the configuration of Embodiment 2 will be described focusing on the differences from Embodiment 1, and the configuration not described in Embodiment 2 is the same as that in Embodiment 1.

[0093] The fixing member 20A of Embodiment 2 is a member having the same function as the fixing member 20 of Embodiment 1. The fixing member 20A of Embodiment 2 has a different shape from the fixing member 20 of Embodiment 1. The fixing member 20A shown in FIGS. 18 and 19 is formed in a T shape in a side view seen in the radial direction RD. The quantity and position of the fixing member 20A are determined in consideration of, for example, the size and shape of the composite segment 100 and the like.

[0094] The fixing member 20A includes a first portion 21A which is a plate-like portion arranged along the radial direction RD, and a second portion 22A which is a plate-like portion arranged along the circumferential direction CD at the tip portion in the protruding direction of the first portion 21A. More specifically, the first portion 21A is a plate-like member extending in the radial direction RD and the axial direction AD. The second portion 22A is a plate-like member extending in the circumferential direction CD and the radial direction RD. One plate surface of the second portion 22A faces the inner surface of one of the pair of main girders 11 in the axial direction AD.

[0095] The fixing member 20A has the first portion 21A joined to the main girder 11 along the axial direction AD from the central portion of the second portion 22A whose plate surface is arranged along the circumferential direction CD. That is, in the fixing member 20A, the base portion of the first portion 21A is joined to the main girder 11, and the tip portion of the first portion 21A is joined to the second portion 22A. The fixing member 20A may be formed by joining the first portion 21A and the second portion 22A by means such as welding, or a pre-integrally formed one may be used.

[0096] As in the case of the fixing member 20A of the modified example shown in FIG. 19(d), at least one or more first through holes 25A may be formed in the first portion 21A. The first portion 21A serves as, for example, a PBL (Perfo-Bond Leisten).

[0097] As shown in FIG. 18, the first force member 48 of the composite segment 100 may be fixed to the fixing member 20A. The composite segment 100 may resist the tensile force applied to the main girder 11 by the fixing member 20A without using the first force member 48.

[0098] [Effect of the composite segment 100 according to Embodiment 2] The fixing member 20A is formed in a T shape when viewed in the radial direction RD. The fixing member 20A includes a first portion 21A that is a plate-like member extending in the radial direction RD and the axial direction AD, and a second portion 22A that is a plate-like member extending in the circumferential direction CD and the radial direction RD, and one plate surface thereof faces the inner surface of one of the pair of main girders 11 in the axial direction AD.

[0099] In the composite segment 100, the bonding force between the main girder 11 and the concrete 80 is strengthened by the fixing member 20A provided on the main girder 11, and peeling from the concrete 80 is suppressed, and the concrete 80 and the main girder 11 are firmly fixed via the fixing member 20A. Therefore, the composite segment 100 can resist the tensile force applied to the main girder 11 by the fixing member 20A as compared with the case where it does not have the fixing member 20A. Further, since the composite segment 100 does not use a vertical rib that connects the pair of main girders 11, which are plate-like members of steel plates, for resisting the tensile force applied to the main girder 11, the amount of steel plate used can be reduced and the cost can be reduced as compared with the case where a vertical rib is used.

[0100] A first through hole 25A is formed in the first portion 21A of the fixing member 20A. In the composite segment 100, since the concrete 80 in the first through hole 25A is three-dimensionally constrained, a large shear strength can be obtained by the fixing member 20A having the first through hole 25A, and a resistance to the tensile force applied to the main girder 11 can be obtained. The composite segment 100 can further resist the tensile force applied to the main girder 11 by the fixing member 20A having the first through hole 25A as compared with the case where it does not have the first through hole 25A.

[0101] When the composite segment 100 has the first force-bearing tendon 48, the strength against loads in the direction in which the distance between the pair of main girders 11 opens is further improved by the combined action of the fixing member 20A and the first force-bearing tendon 48 as compared with the case where only one of these members is present. That is, the composite segment 100 can further resist the tensile force applied to the main girder 11 by the fixing member 20A and the first force-bearing tendon 48 as compared with the case where only one of these members is present.

[0102] Embodiment 3. FIG. 20 is a schematic view showing the internal structure of the steel shell 10 of the composite segment 100 according to Embodiment 3. FIG. 21 is a partially enlarged view of the composite segment 100 according to Embodiment 3. FIG. 22 is a plan view and a side view of the fixing member 20B of the composite segment 100 according to Embodiment 3. FIG. 22(a) is a plan view of the fixing member 20B as viewed in the axial direction AD. FIG. 22(b) is a side view of the fixing member 20B as viewed in the radial direction RD. FIG. 22(c) is a side view of the fixing member 20B as viewed in the circumferential direction CD. For components having the same functions and actions as those of the composite segment 100 according to Embodiment 1 and Embodiment 2, the same reference numerals are given and their descriptions are omitted. Hereinafter, with reference to FIGS. 20 to 22, the configuration of Embodiment 3 will be described centering on the differences from Embodiment 1 and Embodiment 2, and the configurations not described in Embodiment 3 are the same as those in Embodiment 1 and Embodiment 2.

[0103] The fixing member 20B of Embodiment 3 is a member having the same function as the fixing member 20 of Embodiment 1 and the like. The fixing member 20B of Embodiment 3 has a different shape from the fixing member 20 of Embodiment 1. The fixing member 20B shown in FIGS. 20 to 22 is a plate piece formed in an I shape in a side view as viewed in the radial direction RD. The number and position of the fixing members 20B are determined in consideration of, for example, the size and shape of the composite segment 100.

[0104] The fixing member 20B is a plate-shaped member extending in the radial direction RD and the axial direction AD. At least one or more first through-holes 25B are formed in the fixing member 20B. The fixing member 20B serves as, for example, a PBL (Perfo-Bond Leisten).

[0105] As shown in FIG. 21, in the composite segment 100, the first force-carrying bar 48 may be fixed to the fixing member 20B. The composite segment 100 may also be configured to resist the tensile force applied to the main girder 11 by the fixing member 20B without using the first force-carrying bar 48.

[0106] [Effect of the composite segment 100 according to Embodiment 3] The fixing member 20B is a plate-shaped member extending in the radial direction RD and the axial direction AD, and a first through-hole 25B is formed in the fixing member 20B. In the composite segment 100, since the concrete 80 in the first through-hole 25B is three-dimensionally constrained, a large shear resistance can be obtained by the fixing member 20B having the first through-hole 25B, and a resistance to the tensile force applied to the main girder 11 can be obtained. The composite segment 100 can further resist the tensile force applied to the main girder 11 by the fixing member 20B having the first through-hole 25B as compared with the case where the fixing member 20B does not have the first through-hole 25B.

[0107] In the composite segment 100, the bonding force between the main girder 11 and the concrete 80 is strengthened by the fixing member 20B provided on the main girder 11, so that peeling from the concrete 80 is suppressed, and the concrete 80 and the main girder 11 are firmly fixed via the fixing member 20B. Therefore, the composite segment 100 can resist the tensile force applied to the main girder 11 by the fixing member 20B as compared with the case where the fixing member 20B is not provided. Further, since the composite segment 100 does not use vertical ribs connecting the pair of main girders 11, which are plate-shaped members of steel plates for resisting the tensile force applied to the main girders 11, the amount of steel plates used can be reduced and the cost can be reduced as compared with the case of using vertical ribs.

[0108] When the composite segment 100 has the first force-bearing tendon 48, the strength against loads in the direction in which the pair of main girders 11 open wider is improved by the combined action of the fixing member 20B and the first force-bearing tendon 48 as compared with the case where it has only one of these members. That is, the composite segment 100 can resist tensile forces applied to the main girder 11 more effectively by the fixing member 20B and the first force-bearing tendon 48 as compared with the case where it has only one of these members.

[0109] Embodiment 4. FIG. 23 is a partially enlarged view of the composite segment 100 according to Embodiment 4. FIG. 24 is a plan view and a side view of the fixing member 20C of the composite segment 100 according to Embodiment 4. FIG. 24(a) is a plan view of the fixing member 20C as viewed in the axial direction AD. FIG. 24(b) is a side view of the fixing member 20C as viewed in the radial direction RD. FIG. 24(c) is a side view of the fixing member 20C as viewed in the circumferential direction CD. FIG. 24(d) is a side view of a modified fixing member 20C as viewed in the circumferential direction CD. Components having the same functions and actions as those of the composite segment 100 according to Embodiments 1 to 3 are denoted by the same reference numerals and their descriptions are omitted. Hereinafter, with reference to FIGS. 23 and 24, the configuration of Embodiment 4 will be described focusing on the differences from Embodiments 1 to 3, and the configurations not described in Embodiment 4 are the same as those in Embodiments 1 to 3.

[0110] The fixing member 20C of Embodiment 4 is a member having the same function as the fixing member 20 and the like of Embodiment 1. The fixing member 20C of Embodiment 4 has a different configuration from the fixing member 20C of Embodiment 1. The fixing member 20C shown in FIGS. 23 and 24 has a first portion 21C and at least one anchor portion 27. The fixing member 20C may be formed by joining the first portion 21C and the anchor portion 27 by means such as welding, or a pre-formed integral member may be used.

[0111] The first part 21C is a plate piece formed in an I shape in a side view seen in the radial direction RD. The quantity and position of the first part 21C are determined in consideration of, for example, the size and shape of the composite segment 100. The first part 21C is a plate-like member extending in the radial direction RD and the axial direction AD.

[0112] The anchor part 27 is fixed and integrated with the concrete 80 and functions as a so-called anchor. The anchor part 27 is a rod-shaped member. The anchor part 27 has, for example, joints and is a reinforcing bar such as deformed steel bar. The anchor part 27 is fixed to the plate surface facing the circumferential direction CD of the first part 21C. The anchor part 27 is arranged to extend in the axial direction AD. The anchor part 27 is arranged to project from the tip of the first part 21C in the axial direction AD and extend toward the center side of the composite segment 100. The anchor part 27 may be parallel to the axial direction AD or may be inclined with respect to the axial direction AD.

[0113] In FIG. 24, the fixing member 20C has two anchor parts 27 arranged in the radial direction RD, but the number of the anchor parts 27 is not limited to two, and may be one or three or more. The quantity and position of the anchor part 27 are determined in consideration of, for example, the size and shape of the composite segment 100.

[0114] As in the fixing member 20C of the modification shown in FIG. 24(d), at least one or more first through holes 25C may be formed in the first part 21C. The first part 21C serves as, for example, a PBL (Perfo - Bond Leisten).

[0115] The composite segment 100 may have the first force - resisting bars 48 (not shown) fixed to the first part 21C of the fixing member 20C. The composite segment 100 may also resist the tensile force applied to the main girder 11 by the fixing member 20C without using the first force - resisting bars 48.

[0116] [Effect of the composite segment 100 according to Embodiment 4] The fixing member 20C includes a first portion 21C which is a plate-like member extending in the radial direction RD and the axial direction AD, and at least one or more anchor portions 27. The anchor portion 27 is a rod-shaped member fixed to the plate surface of the first portion 21C facing the circumferential direction CD, and is arranged so as to protrude and extend from the tip of the first portion 21C in the axial direction AD.

[0117] In the composite segment 100, the bonding force between the main girder 11 and the concrete 80 is strengthened by the fixing member 20C provided on the main girder 11, and peeling from the concrete 80 is suppressed, and the concrete 80 and the main girder 11 are firmly fixed via the fixing member 20C. Therefore, the composite segment 100 can resist the tensile force applied to the main girder 11 by the fixing member 20C as compared with the case where the fixing member 20C is not provided. Further, since the composite segment 100 does not use the vertical ribs connecting the pair of main girders 11 which are plate-like members of steel plates for resisting the tensile force applied to the main girder 11, the amount of steel plate used can be reduced and the cost can be reduced as compared with the case where vertical ribs are used.

[0118] A first through-hole 25C is formed in the first portion 21C of the fixing member 20C. Since the concrete 80 in the first through-hole 25C of the composite segment 100 is three-dimensionally constrained, a large shear strength can be obtained by the fixing member 20C having the first through-hole 25C, and a resistance to the tensile force applied to the main girder 11 can be obtained. The composite segment 100 can further resist the tensile force applied to the main girder 11 by the fixing member 20C having the first through-hole 25C as compared with the case where the first through-hole 25C is not provided.

[0119] When the composite segment 100 has the first force-reinforcing bars 48, the strength against the load in the direction in which the pair of main girders 11 open is further improved by the combined action of the fixing member 20C and the first force-reinforcing bars 48 as compared with the case where only one of these members is provided. That is, the composite segment 100 can further resist the tensile force applied to the main girder 11 by the fixing member 20C and the first force-reinforcing bars 48 as compared with the case where only one of these members is provided.

[0120] Embodiment 5. FIG. 25 is a partially enlarged view of the composite segment 100 according to Embodiment 5. FIG. 26 is a plan view and a side view of the fixing member 20D of the composite segment 100 according to Embodiment 5. FIG. 26(a) is a plan view of the fixing member 20D viewed in the axial direction AD. FIG. 26(b) is a side view of the fixing member 20D viewed in the radial direction RD. FIG. 26(c) is a side view of the fixing member 20D viewed in the circumferential direction CD. FIG. 26(d) is a side view of a modified example of the fixing member 20D viewed in the radial direction RD. Components having the same functions and actions as those of the composite segment 100 according to Embodiments 1 to 4 are denoted by the same reference numerals and their descriptions are omitted. Hereinafter, with reference to FIGS. 25 and 26, the configuration of Embodiment 5 will be described centering on the points different from those of Embodiments 1 to 4, and the configurations not described in Embodiment 5 are the same as those of Embodiments 1 to 4.

[0121] The fixing member 20D of Embodiment 5 is a member having the same function as the fixing member 20 or the like of Embodiment 1. The fixing member 20D of Embodiment 5 has a different configuration from that of the fixing member 20 of Embodiment 1. The fixing member 20D shown in FIGS. 25 and 26 is formed in a U shape in a side view viewed in the radial direction RD. The quantity and position of the fixing member 20D are determined in consideration of, for example, the size and shape of the composite segment 100 and the like.

[0122] The fixing member 20D includes a first portion 21D that is a plate-like portion arranged along the circumferential direction CD, and a pair of second portions 22D that are plate-like portions arranged along the radial direction RD at both ends of the first portion 21D in the circumferential direction CD. More specifically, the first portion 21D is a plate-like member extending in the circumferential direction CD and the radial direction RD. The second portion 22D is a plate-like member extending in the radial direction RD and the axial direction AD. One plate surface of the first portion 21D abuts on the inner surface of one of the pair of main girders 11 in the axial direction AD.

[0123] The fixing member 20D has a pair of second portions 22D extending from both ends of the first portion 21D whose plate surface is arranged along the circumferential direction CD toward the center side of the composite segment 100 along the axial direction AD, and the second portions 22D are joined to the first portion 21D. The fixing member 20D may be formed by joining the first portion 21D and the second portions 22D by means such as welding, or a pre-formed integral member may be used.

[0124] In the first portion 21D, a fixing through-hole 26D for inserting a fixture 30 that connects the main girders 11 of adjacent composite segments 100 is formed. As shown in FIG. 25, the fixture 30 is inserted into the fixing through-hole 26D. The fixture 30 is also inserted into the main girders 11 of the composite segments 100 adjacent in the axial direction AD and is used for fixing the main girders 11 of the composite segments 100 adjacent in the axial direction AD to each other. The fixture 30 is, for example, a bolt and a nut or the like. The fixing member 20D is fixed to the pair of main girders 11 by the fixture 30.

[0125] As shown in FIG. 25, the fixing member 20D does not need to be fixed to the main girder 11 by welding, and is fixed to the main girder 11 by a fixture 30 that fixes the main girders 11 to each other when fixing the main girders 11 of the composite segments 100 adjacent in the axial direction AD. The fixing member 20D is fixed to, for example, a bolt hole 13 (see FIG. 3) or the like. Note that the fixing method of the fixing member 20D is not limited to this method, and it may be fixed to the main girder 11 by welding.

[0126] As shown in FIG. 26(c), at least one or more first through-holes 25D are formed in the second portion 22D. The second portion 22D serves as, for example, a PBL (Perfo-Bond Leisten).

[0127] In the composite segment 100, a first force member 48 (not shown) may be fixed to the fixing member 20D. The composite segment 100 may be configured to resist the tensile force applied to the main girder 11 by the fixing member 20D without using the first force member 48.

[0128] As shown in FIG. 26(d), the fixing member 20D may have a third portion 23D. The fixing member 20D of the modified example includes a third portion 23D which is a plate-like portion arranged along the circumferential direction CD at the tip of the protruding direction of the second portion 22D. The third portion 23D is a plate-like member extending in the circumferential direction CD and the radial direction RD. One plate surface of the third portion 23D faces the inner surface of one of the pair of main girders 11 in the axial direction AD.

[0129] In the case of viewing the fixing member 20D of the modified example in the radial direction RD, the portions of the second portion 22D and the third portion 23D are formed in a T shape. The fixing member 20D of the modified example has T-shaped portions formed by the second portion 22D and the third portion 23D at both ends of the first portion 21D in the circumferential direction CD. That is, the fixing member 20D has two T-shaped portions in the circumferential direction CD.

[0130] [Effect of the composite segment 100 according to Embodiment 5] The fixing member 20D is formed in a U shape when viewed in the radial direction RD. The fixing member 20D includes a first portion 21D and a pair of second portions 22D. The first portion 21D is a plate-like member extending in the circumferential direction CD and the radial direction RD, and one plate surface abuts against the inner surface of one of the pair of main girders 11 in the axial direction AD. The second portion 22D is a plate-like member extending in the radial direction RD and the axial direction AD, and is provided at both ends of the first portion 21D in the circumferential direction CD. A fixing through hole 26D for inserting a fixture 30 that connects the main girders 11 of adjacent composite segments 100 is formed in the first portion 21D. The fixing member 20D is fixed to the pair of main girders 11 by the fixture 30.

[0131] The composite segment 100 has its bonding force with the concrete 80 strengthened by the fixing member 20D provided on the main girder 11, thus suppressing the peeling from the concrete 80, and the concrete 80 and the main girder 11 are firmly fixed via the fixing member 20D. Therefore, the composite segment 100 can, by means of the fixing member 20D, resist the tensile force applied to the main girder 11 as compared with the case without the fixing member 20D. Further, since the composite segment 100 does not use the vertical ribs connecting the pair of main girders 11 which are plate-shaped members of steel plates for resisting the tensile force applied to the main girder 11, the amount of steel plate used can be reduced and the cost can be reduced as compared with the case of using the vertical ribs. Also, since the fixing member 20D can be fixed to the main girder 11 by the fixture 30, welding is not required for fixing the fixing member 20D and the main girder 11.

[0132] Further, a first through-hole 25D is formed in the second portion 22D of the fixing member 20D. Since the concrete 80 in the first through-hole 25D of the composite segment 100 is three-dimensionally constrained, a large shear resistance can be obtained by the fixing member 20D having the first through-hole 25D, and a resistance to the tensile force applied to the main girder 11 can be obtained. The composite segment 100 can, by means of the fixing member 20D having the first through-hole 25D, further resist the tensile force applied to the main girder 11 as compared with the case without the first through-hole 25D.

[0133] Also, the fixing member 20D is a plate-shaped member extending in the circumferential direction CD and the radial direction RD, and further includes a third portion 23D whose one plate surface faces the inner surface of one of the pair of main girders 11 in the axial direction AD. The fixing member 20D is formed in a T shape when viewed in the radial direction RD at the portions of the second portion 22D and the third portion 23D.

[0134] The composite segment 100 has its bonding force with the main girder 11 and the concrete 80 strengthened by a fixing member 20D having a T-shaped portion, and peeling from the concrete 80 is suppressed, and the concrete 80 and the main girder 11 are firmly fixed via the fixing member 20D. Therefore, the composite segment 100 can, by means of the fixing member 20D, resist the tensile force applied to the main girder 11 as compared with the case where the fixing member 20D is not provided.

[0135] When the composite segment 100 has the first force-resistant bars 48, due to the combined action of the fixing member 20D and the first force-resistant bars 48, the strength against loads in the direction in which the space between the pair of main girders 11 opens is further improved as compared with the case where only one of these members is provided. That is, the composite segment 100 can, by means of the fixing member 20D and the first force-resistant bars 48, further resist the tensile force applied to the main girder 11 as compared with the case where only one of these members is provided.

[0136] Embodiment 6. FIG. 27 is a partially enlarged view of the composite segment 100 according to Embodiment 6. FIG. 28 is a plan view and a side view of the fixing member 20E of the composite segment 100 according to Embodiment 6. FIG. 28(a) is a plan view of the fixing member 20E as viewed in the axial direction AD. FIG. 28(b) is a side view of the fixing member 20E as viewed in the radial direction RD. FIG. 28(c) is a side view of the fixing member 20E as viewed in the circumferential direction CD. FIG. 28(d) is a side view of a modified example of the fixing member 20E as viewed in the radial direction RD. For components having the same functions and actions as those of the composite segment 100 according to Embodiments 1 to 5, the same reference numerals are given and their descriptions are omitted. Hereinafter, with reference to FIGS. 27 and 28, the configuration of Embodiment 6 will be described focusing on the differences from Embodiments 1 to 5, and the configurations not described in Embodiment 6 are the same as those in Embodiments 1 to 5.

[0137] The fixing member 20E of Embodiment 6 is a member having the same function as the fixing member 20 and the like of Embodiment 1. The fixing member 20E of Embodiment 6 has a different configuration from the fixing member 20 of Embodiment 1. The fixing member 20E shown in FIGS. 27 and 28 is formed in a U shape in a side view seen in the radial direction RD. The quantity and position of the fixing member 20E are determined in consideration of, for example, the size and shape of the composite segment 100 and the like.

[0138] The fixing member 20E includes a first portion 21E that is a plate-like portion arranged along the circumferential direction CD, and second portions 22E that are plate-like portions arranged along the radial direction RD at both ends of the first portion 21E in the circumferential direction CD. More specifically, the first portion 21E is a plate-like member extending in the circumferential direction CD and the radial direction RD. The second portion 22E is a plate-like member extending in the radial direction RD and the axial direction AD. One plate surface of the first portion 21E faces and abuts against the inner surface of the main girder 11 in the axial direction AD.

[0139] The fixing member 20E has a pair of second portions 22E that extend from both ends of the first portion 21E whose plate surface is arranged along the circumferential direction CD toward the center side of the composite segment 100 along the axial direction AD and are joined to the first portion 21E. The fixing member 20E may be formed by joining the first portion 21E and the second portions 22E by means such as welding, or a pre-formed integral member may be used.

[0140] A fixing through hole 26E that serves the same role as the fixing through hole 26D of Embodiment 5 is formed in the first portion 21E. As shown in FIG. 27, a fixture 30 is inserted through the fixing through hole 26E.

[0141] The fixing member 20E has at least one or more anchor portions 27E in the second portion 22E. The fixing member 20E may be formed by joining the second portion 22E and the anchor portions 27E by means such as welding, or a pre-formed integral member may be used. The anchor portion 27E is a rod-shaped member and is the same member as the anchor portion 27 of Embodiment 4.

[0142] The anchor part 27E is fixed to the plate surface of the second part 22E facing the circumferential direction CD. The anchor part 27E is arranged to extend in the axial direction AD. The anchor part 27E is arranged to project from the tip of the second part 22E in the axial direction AD and extend toward the center side of the composite segment 100.

[0143] In FIG. 28, the fixing member 20E has two anchor parts 27E arranged in the radial direction RD in the second part 22E. However, the number of the anchor parts 27E is not limited to two, and may be one or three or more. The quantity and position of the anchor parts 27E are determined in consideration of, for example, the size and shape of the composite segment 100.

[0144] As in the fixing member 20E of the modification shown in FIG. 28(d), at least one or more first through holes 25E may be formed in the second part 22E. The second part 22E serves as, for example, a PBL (Perfo - Bond Leisten) divel.

[0145] The composite segment 100 may have the first force - resisting bars 48 (not shown) fixed to the fixing member 20E. The composite segment 100 may also resist the tensile force applied to the main girder 11 by the fixing member 20E without using the first force - resisting bars 48.

[0146] [Effect of the composite segment 100 according to Embodiment 6] The fixing member 20E is a rod - shaped member fixed to the plate surface of the second part 22E facing the circumferential direction CD, and includes at least one or more anchor parts 27E arranged to project and extend from the tip of the second part 22E in the axial direction AD.

[0147] The composite segment 100 has its bonding force with the main girder 11 and the concrete 80 strengthened by the fixing member 20E of this structure, and peeling from the concrete 80 is suppressed, and the concrete 80 and the main girder 11 are firmly fixed via the fixing member 20E. Therefore, the composite segment 100 can resist the tensile force applied to the main girder 11 by the fixing member 20E as compared with the case where the fixing member 20E is not provided. Further, since the composite segment 100 does not use the vertical ribs that connect the pair of main girders 11 which are plate-shaped members of steel plates for resisting the tensile force applied to the main girder 11, the amount of steel plate used can be reduced and the cost can be reduced as compared with the case where vertical ribs are used.

[0148] Further, a first through hole 25E is formed in the second portion 22E of the fixing member 20E. Since the concrete 80 in the first through hole 25E is three-dimensionally constrained in the composite segment 100, a large shear strength can be obtained by the fixing member 20E having the first through hole 25E, and a resistance to the tensile force applied to the main girder 11 can be obtained. The composite segment 100 can further resist the tensile force applied to the main girder 11 by the fixing member 20E having the first through hole 25E as compared with the case where the first through hole 25E is not provided.

[0149] When the composite segment 100 has the first force reinforcement 48, the strength against the load in the direction in which the pair of main girders 11 open is further improved by the combined action of the fixing member 20E and the first force reinforcement 48 as compared with the case where only one of these members is provided. That is, the composite segment 100 can further resist the tensile force applied to the main girder 11 by the fixing member 20E and the first force reinforcement 48 as compared with the case where only one of these members is provided.

[0150] [Effect of the earth retaining structure 200] The earth retaining structure 200 is formed by combining a plurality of the composite segments 100 of any one or more of Embodiments 1 to 6 in the circumferential direction CD and the axial direction AD. Therefore, the earth retaining structure 200 exhibits the same effects as the composite segment 100 of Embodiments 1 to 6.

[0151] Although the embodiments have been described above, the present disclosure is not limited only to the configurations of the above embodiments. In particular, the combination of components is not limited only to the combinations in the embodiments, and can be changed as appropriate. For example, the fixing member 20 can also be used in combination with the fixing members 20A to 20E, etc., which are modification examples. Also, for the sake of reminder, the scope of various changes, applications, and uses made by those skilled in the art as needed is also included in the technical scope.

[0152] The composite segment 100 described above may also include combinations of each of the features shown in the following Appendices 1 to 15. The combinations are shown below. [Appendix 1] A composite segment that constitutes a cylindrical body embedded as an earth retaining structure, A pair of main girders extending in the circumferential direction of the cylindrical body and having plate surfaces facing each other in the axial direction of the cylindrical body, A pair of joint plates joined to both ends in the circumferential direction of each of the pair of main girders, A skin plate joined to the outer peripheral side in the radial direction of the cylindrical body with respect to the frame body constituted by the pair of main girders and the pair of joint plates, At least one or more fixing members provided so as to protrude from one main girder toward the other main girder on the inner surfaces of the pair of main girders, fixed to the concrete filled inside the frame body and the skin plate, and configured to resist the tensile force applied to the pair of main girders in the direction in which the pair of main girders move apart, A composite segment comprising. [Appendix 2] The fixing member is, A first portion arranged such that the plate surface extends in the circumferential direction and the axial direction, A second portion arranged such that the plate surface extends in the radial direction and the axial direction, Comprising, The fixing member is, The composite segment according to Appendix 1, in which a first through hole is formed in the first portion. [Appendix 3] The fixing member is the synthetic segment according to Appendix 2, in which a second through hole is formed in the second portion. [Appendix 4] further provided with a reinforcing bar unit disposed between the pair of main girders, the reinforcing bar unit is provided with a first force-bearing bar extending in the axial direction, the fixing member is provided at positions facing each other in the axial direction on each of the pair of main girders so as to be in pairs, both ends of the first force-bearing bar are fixed to the fixing member, the synthetic segment according to Appendix 2 or 3. [Appendix 5] the first force-bearing bar is provided with a main body portion extending in the axial direction, and insertion portions extending in the radial direction from both ends of the main body portion, and is the insertion portions are inserted into the first through hole, the synthetic segment according to Appendix 4. [Appendix 6] the fixing member is formed in a T shape when viewed in the radial direction, a first portion which is a plate-like member extending in the radial direction and the axial direction, and a second portion which is a plate-like member extending in the circumferential direction and the radial direction, and one plate surface thereof faces the inner surface of one of the pair of main girders in the axial direction, the synthetic segment according to Appendix 1. [Appendix 7] the fixing member is a plate-like member extending in the radial direction and the axial direction, the fixing member is provided with a first through hole, the synthetic segment according to Appendix 1. [Appendix 8] the fixing member is a first portion which is a plate-like member extending in the radial direction and the axial direction, and A rod-shaped member fixed to the circumferentially facing plate surface of the first portion, and at least one or more anchor portions arranged to project and extend from the tip of the first portion in the axial direction. The composite segment according to appended claim 1, comprising . [Appended claim 9] The composite segment according to appended claim 6 or 8, wherein a through hole is formed in the first portion. [Appended claim 10] The fixing member is formed in a U shape when viewed in the radial direction, is a plate-shaped member extending in the circumferential direction and the radial direction, and a first portion whose one plate surface abuts against the inner surface of one of the pair of main girders in the axial direction; is a plate-shaped member extending in the radial direction and the axial direction, and a pair of second portions provided at both ends of the first portion in the circumferential direction; comprises In the first portion, a fixing through hole for inserting a fixture connecting the main girders of adjacent composite segments is formed, The fixing member is fixed to the pair of main girders by the fixture, and is the composite segment according to appended claim 1. [Appended claim 11] The composite segment according to appended claim 10, wherein a first through hole is formed in the second portion. [Appended claim 12] The fixing member is a plate-shaped member extending in the circumferential direction and the radial direction, and further comprises a third portion whose one plate surface faces the inner surface of one of the pair of main girders in the axial direction, The composite segment according to appended claim 10 or 11, wherein the portion composed of the pair of second portions and the third portion is formed in a T shape when viewed in the radial direction. [Appended claim 13] The fixing member A rod-shaped member fixed to the circumferentially facing plate surfaces of the pair of second parts, and comprising at least one or more anchor parts arranged so as to project and extend from the tips of the pair of second parts in the axial direction. The composite segment according to appended claim 10 or 11. [Appended claim 14] Further comprising a reinforcing bar unit arranged between the pair of main girders, The reinforcing bar unit, Comprises a first force-bearing bar extending in the axial direction, The fixing member, Is provided at positions facing each other in the axial direction on each of the pair of main girders so as to be paired, Both ends of the first force-bearing bar, Are fixed to the fixing member. The composite segment according to any one of appended claims 6 to 8. [Appended claim 15] An earth retaining structure formed by combining a plurality of the composite segments according to any one of appended claims 1 to 14 in the circumferential direction and the axial direction.

Explanation of reference signs

[0153] 10 Steel shell, 11 Main girder, 12 Joint plate, 13 Bolt hole, 14 Boss, 15 Bolt hole, 16 Skin plate, 20 Fixing member, 20A Fixing member, 20B Fixing member, 20C Fixing member, 20D Fixing member, 20E Fixing member, 21 First part, 21A First part, 21C First part, 21D First part, 21E First part, 22 Second part, 22A Second part, 22D Second part, 22E Second part, 23 Shape retaining member, 23D Third part, 23a End face, 25 First through hole, 25A First through hole, 25B First through hole, 25C First through hole, 25D First through hole, 25E First through hole, 26 Second through hole, 26D Fixing through hole, 26E Fixing through hole, 27 Anchor part, 27E Anchor part, 30 Fixture, 40 Reinforcement unit, 40A Reinforcement unit, 41 Reinforcement cage, 42 First main reinforcement, 43 Second main reinforcement, 45 Second distribution reinforcement, 45a Body part, 45b Arm part, 45c Tip part, 48 First distribution reinforcement, 48A First distribution reinforcement, 48a Insertion part, 48b Body part, 80 Concrete, 81 Bolt box, 82 Bolt box, 90 Ground, 91 Hollow part, 92 Connecting part, 93 Connecting part, 100 Composite segment, 150 Segment ring, 200 Earth retaining structure, 300 Shield machine, AD Axial direction, CD Circumferential direction, RD Radial direction.

Claims

1. A composite segment that constitutes a cylindrical body embedded as a soil retaining structure, a pair of main girders that extend in the circumferential direction of the cylindrical body and are arranged with their plate surfaces facing each other in the axial direction of the cylindrical body, a pair of joint plates joined to both ends in the circumferential direction of each of the pair of main girders, a skin plate joined to the outer peripheral side in the radial direction of the frame body constituted by the pair of main girders and the pair of joint plates, at least one or more fixing members provided so as to protrude from one main girder toward the other main girder on the inner surfaces of the pair of main girders, fixed to the concrete filled inside the frame body and the skin plate, and configured to resist the tensile force applied to the pair of main girders in the direction in which the pair of main girders separate, A composite segment comprising the above.

2. The fixing member, a first portion arranged such that its plate surface extends in the circumferential direction and the axial direction, a second portion arranged such that its plate surface extends in the radial direction and the axial direction, and comprises, The fixing member, The composite segment according to claim 1, wherein a first through hole is formed in the first portion.

3. The fixing member, The composite segment according to claim 2, wherein a second through hole is formed in the second portion.

4. Further comprising a reinforcing bar unit arranged between the pair of main girders, The reinforcing bar unit, comprises a first force-bearing bar extending in the axial direction, The fixing member, is provided at positions opposite to each other in the axial direction on each of the pair of main girders, Both ends of the first force-bearing bar, are fixed to the fixing member. The composite segment according to claim 2 or 3.

5. The first force-bearing bar, a main body portion extending in the axial direction, insertion portions extending in the radial direction from both ends of the main body portion, and comprises, The insertion portion, is inserted into the first through hole. The composite segment according to claim 4.

6. The fixing member, is formed in a T shape when viewed in the radial direction, a first portion that is a plate-like member extending in the radial direction and the axial direction, a second portion that is a plate-like member extending in the circumferential direction and the radial direction, and one plate surface of which faces the inner surface of one of the pair of main girders in the axial direction, and comprises. The composite segment according to claim 1.

7. The fixing member, is a plate-like member extending in the radial direction and the axial direction, In the fixing member, The composite segment according to claim 1, in which a first through hole is formed.

8. The fixing member is a first portion which is a plate-like member extending in the radial direction and the axial direction, a rod-like member fixed to the circumferentially facing plate surface of the first portion, and at least one or more anchor portions arranged so as to protrude and extend from the tip of the first portion in the axial direction, The composite segment according to claim 1, comprising:

9. The composite segment according to claim 6 or 8, in which a through hole is formed in the first portion.

10. The fixing member is formed in a U shape when viewed in the radial direction, a plate-like member extending in the circumferential direction and the radial direction, a first portion in which one plate surface abuts against the inner surface of one of the pair of main girders in the axial direction, a plate-like member extending in the radial direction and the axial direction, and a pair of second portions provided at both ends of the first portion in the circumferential direction, comprising In the first portion, a fixing through hole for inserting a fixture for connecting the main girders of adjacent composite segments is formed, The fixing member is fixed to the pair of main girders by the fixture. The composite segment according to claim 1.

11. The composite segment according to claim 10, in which a first through hole is formed in each of the pair of second portions.

12. The fixing member is a plate-like member extending in the circumferential direction and the radial direction, and further includes a third portion in which one plate surface faces the inner surface of one of the pair of main girders in the axial direction, The composite segment according to claim 10 or 11, in which the portion constituted by the pair of second portions and the third portion is formed in a T shape when viewed in the radial direction.

13. The fixing member is a rod-like member fixed to the circumferentially facing plate surfaces of the pair of second portions, and includes at least one or more anchor portions arranged so as to protrude and extend from the tips of the pair of second portions in the axial direction. The composite segment according to claim 10 or 11.

14. Further provided with a reinforcing bar unit arranged between the pair of main girders, The reinforcing bar unit is provided with a first force-bearing bar extending in the axial direction, The fixing member is provided at positions facing each other in the axial direction on each of the pair of main girders, Both ends of the first force-bearing bar are The synthetic segment according to any one of claims 6 to 8, which is fixed to the fixing member. **Claim 15** An earth retaining structure formed by combining a plurality of the synthetic segments according to any one of claims 1 to 3 in the circumferential direction and the axial direction.

Images