Composite segment and soil retainer structure

Abstract

To provide a composite segment and a soil retainer structure that can prevent deformation of joint plates of a composite segment that has no longitudinal rib, preventing detachment of concrete.SOLUTION: A composite segment comprises: a pair of girders that extend in the circumference direction of a 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 reinforcement rib that is fixed to the one joint plate of the pair of joint plates in the circumference direction, arranged in the pair of joint plates so as to protrude from the one joint plate to the other on the inner surface of each of the pair of joint plates, suppressing the movement in the circumference direction by being fixed with concrete filled inside the frame body and the skin plate, to compose a part for resisting the tensile force caused on the pair of joint plates.SELECTED DRAWING: Figure 11

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 shafts or tunnels have been 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. In order to resist the tensile force in the axial direction of the tunnel, the synthetic segment is provided with a plate-like member made of steel plate called a plurality of vertical ribs that connect the opposing main girders inside the steel shell (see, for example, Patent Document 1). Both ends of the vertical rib are joined by being welded to the inner surface of the main girder, for example.

[0003] A plurality of synthetic segments are arranged in the circumferential direction of the tunnel, and the joint plates of adjacent synthetic segments are fixed to each other using a fixture such as a bolt, and adjacent synthetic segments are joined together to form an annular segment ring. The segment ring may have a tensile force acting between the pieces of adjacent synthetic segments in the circumferential direction due to, for example, non-uniform earth pressure applied to the segment ring, the self-weight of the segment ring, the state of segment ring support, and other non-uniform pressures. In addition, the segment ring may have a tensile force acting between the pieces of adjacent synthetic segments in the circumferential direction due to the internal pressure of the tunnel formed by the segment ring.

[0004] In order to cope with the tensile force between such pieces, a connecting member that connects the longitudinal ribs and the joint plate at both ends can be considered, and a connecting member arranged in parallel with the main girder can be provided. When the composite segment has a connecting member connected to the longitudinal rib and the joint plate, the composite segment can bear the part that resists the tensile force applied to the joint plate by the longitudinal rib via the connecting member against the tensile force between the pieces.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the composite segment disclosed in Patent Document 1, the longitudinal rib is formed of a rectangular plate-shaped steel material (steel plate) and is arranged substantially perpendicular to the main girder between the main girders. The composite segment of Patent Document 1 uses a plurality of longitudinal ribs arranged at predetermined intervals, and there is a problem that the amount of steel plate used is large and the cost is high. When the longitudinal rib is not used to reduce the cost, since there is no longitudinal rib, the segment ring cannot transmit the bolt tension to the longitudinal rib via the connecting member against the tensile force between the pieces of the composite segment. Therefore, the joint plate of the composite segment may be deformed and peeled off from the concrete.

[0007] The present disclosure solves the above problems, and an object thereof is to provide a composite segment and an earth retaining structure that can prevent deformation of the joint plate and peeling of the concrete in a composite segment having no longitudinal rib.

Means for Solving the Problems

[0008] The synthetic segment according to the present disclosure is a synthetic segment that constitutes a cylindrical body to be embedded as a 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 the frame body constituted by the pair of main girders and the pair of joint plates, and at least one or more reinforcing ribs that are fixed to the concrete filled inside the frame body and the skin plate, are provided on each of the pair of joint plates so as to protrude from one joint plate toward the other joint plate side on the inner surface of the pair of joint plates, suppress circumferential movement, and constitute a portion that resists the tensile force applied to the pair of joint plates.

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

Effect of the Invention

[0010] The synthetic segment of the present disclosure includes reinforcing ribs provided on each of the pair of joint plates so as to be fixed to one of the pair of joint plates in the circumferential direction and protrude from one joint plate toward the other joint plate side on the inner surface of the pair of joint plates. The reinforcing ribs 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, suppress circumferential movement, and constitute a portion that resists the tensile force applied to the pair of joint plates. The synthetic segment can enhance the bonding force with the concrete by the reinforcing ribs to ensure the pull-out resistance and can resist the tensile force applied to the joint plates in the circumferential direction of the tunnel. Therefore, even when the synthetic segment does not have longitudinal ribs which are plate-shaped members of steel plates connecting the main girders, it can prevent the deformation of the joint plates and the peeling of the concrete.

Brief Description of the Drawings

[0011]

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Embodiments for Carrying Out the Invention

[0012] Hereinafter, the synthetic segment and the earth retaining structure according to the embodiment 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 constituent members may be different from the actual ones. Further, in the following drawings, those denoted by the same reference numerals are the same or corresponding thereto, and this shall be common throughout the entire specification. In addition, terms indicating directions (for example, up, down, left, right, front, rear, front and back, etc.) are appropriately used for ease of understanding, but their notations are for convenience of explanation and do not limit the arrangement, direction, and orientation of the device, instrument, or parts, 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, and the circumferential direction CD represents the circumferential direction of the earth retaining structure 200. Further, 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. In addition, 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 necessarily 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 ground. The earth retaining structure 200 is installed underground and is used as an earth retaining wall for tunnels constituting subways, road tunnels, sewers, power, 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 jacked caisson method.

[0015] When the earth retaining structure 200 is used as an earth retaining wall in the shield method, the earth retaining structure 200 covers the underground excavation surface in the 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 in the jacked caisson method, the earth retaining structure 200 covers the underground excavation surface in the construction method such as the jacking 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 in the shield method, the earth retaining structure 200 is arranged so as to extend in the advancing direction of the shield machine. For example, in the ground, the cylindrical axial direction AD extends horizontally or is inclined with respect to the horizontal direction. When the earth retaining structure 200 is used as an earth retaining wall in the jacked 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, for example, when viewed in the axial direction AD, it may be formed in other shapes such as an oval shape, a rectangular shape, or a square shape with rounded corners.

[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 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 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 rectangular shape, or a quadrangular 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 extending direction of the earth retaining structure 200, 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 composed of 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 extending direction of the tunnel 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 an annular shape, and the segment ring 150 is formed by connecting adjacent composite segments 100 to each other by the connecting portion 92. Note that the segment ring 150 shown in FIG. 2 is described such that the sizes of the composite segments 100 are substantially equal in the circumferential direction CD, but the sizes of the composite segments 100 may be formed to be different from each other 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 the axial direction AD are assembled in an arrangement state in which 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 so as to be 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 peripheral side. FIG. 4 is a perspective view of an example of the composite segment 100 according to Embodiment 1 as viewed from the outer peripheral 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.

[0024] 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. Further, the overall structure of the composite segment 100 is explained using FIGS. 3 to 6, and in FIGS. 3 to 6, the illustration of the reinforcing ribs 50, which will be described later, provided on the inner surface side of the joint plate 12 is omitted. FIGS. 3 and 4 are illustrated with the top and bottom reversed. FIG. 7 is a schematic cross-sectional view taken along line A-A in FIG. 6. The composite segment 100 will be described using FIGS. 3 to 7.

[0025] The synthetic segment 100 constitutes a cylindrical body to be embedded as a 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 retaining structure 200 by being connected in a plurality in the circumferential direction CD and the axial direction AD of the retaining structure 200. The synthetic segment 100 has a box-shaped structure formed by combining 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.

[0026] 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.

[0027] [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 bundled and integrated 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.

[0028] As shown in Fig. 7, the steel bar cage 41 is formed by joining a first main reinforcement 42, a second main reinforcement 43, and a second stirrup 45. The first main reinforcement 42 extends in the circumferential direction CD, and a plurality of them are arranged at intervals in the axial direction AD. Also, the second main reinforcement 43 is arranged at an interval in the radial direction RD with respect to the first main reinforcement 42. The second main reinforcement 43 also extends in the circumferential direction CD like the first main reinforcement 42, and a plurality of them are arranged at intervals in the axial direction AD. Note that the number of the first main reinforcement 42 and the second main reinforcement 43 is not limited to a plurality, and may be a single number.

[0029] As shown in Figs. 6 and 7, the steel bar cage 41 includes two rows of main reinforcements, a first main reinforcement 42 arranged on the inner circumferential side and a second main reinforcement 43 arranged on the outer circumferential 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 reinforcements in the radial direction RD, or may include three or more rows of main reinforcements.

[0030] 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 42 and the second main reinforcement 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 the end 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.

[0031] The second stirrup 45 is formed in a shape like a square with a loop or a shape in which a part of the square with a loop is cut out so as to surround the rows of the first main reinforcement 42 and the second main reinforcement 43 from the outside. The second stirrup 45 may be arranged on the inner circumferential side with respect to the first main reinforcement 42 in the radial direction RD as shown in Figs. 3 and 5, or may be arranged on the outer circumferential side with respect to the second main reinforcement 43 as shown in Figs. 5 and 7.

[0032] The second force-bearing reinforcement 45 is a reinforcing bar and may be formed by bending a single bar or by combining a plurality of bars. The second force-bearing 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-bearing 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-bearing reinforcements 45 is not limited to a plurality and may be a single one.

[0033] The reinforcing bar unit 40 includes a first force-bearing reinforcement 48 extending in the axial direction AD. Both ends of the first force-bearing reinforcement 48 are fixed to the fixing member 20. The first force-bearing 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-bearing reinforcement 48 is arranged in parallel with the second force-bearing reinforcement 45 in the radial direction RD.

[0034] The first force-bearing reinforcement 48 is arranged adjacent to the second force-bearing reinforcement 45 and is combined with the second force-bearing 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-bearing reinforcement 48 may be arranged at an interval from the second force-bearing reinforcement 45 in the radial direction RD. Also, the first force-bearing reinforcement 48 may be arranged at an interval from the second force-bearing reinforcement 45 in the circumferential direction CD.

[0035] The first force-bearing reinforcement 48 is a reinforcing bar and may be formed by bending a single bar or by combining a plurality of bars. The first force-bearing 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-bearing 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 first through holes 25 provided in the fixing member 20 described later. The main body portion 48b of the first force-bearing reinforcement 48 is arranged adjacent to the first main reinforcement 42 of the reinforcing bar cage 41.

[0036] [Steel shell 10] As shown in FIGS. 3 and 4, the steel shell 10 of the composite segment 100 is provided with a pair of arc-shaped main girders 11 that are spaced apart in the axial direction AD and have 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 sides of the main girder 11 and the joint plates 12. The steel shell 10 is formed in a box shape by welding these main girders 11, joint plates 12, and skin plate 16 to each other. The steel shell 10 of the composite segment 100 does not have so-called longitudinal 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 girders 11.

[0037] 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 are connected to each other in the axial direction AD of the earth retaining structure 200 and the segment ring 150.

[0038] 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 girders 11 are 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 form one end surface and the other end surface of the composite segment 100 in the axial direction AD.

[0039] 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.

[0040] 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. As an example, 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.

[0041] As shown in Fig. 3, in the synthetic segment 100, bolt boxes 81 are provided at positions corresponding to the bolt holes 13 in the concrete 80. The bolt box 81 forms a space in the synthetic segment 100 to expose the bolt holes 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.

[0042] 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. Mounting holes having female threads for screwing bolts are formed in the bosses 14.

[0043] 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 through the bolt holes 13, and screws them into the female 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 through the bolt holes 13 into the female threads of the bosses 14, the two adjacent synthetic segments 100 in the axial direction AD are connected.

[0044] The number of bolt holes 13 and bosses 14 formed is not limited to the illustrated embodiment, and is determined, for example, in consideration of the size and shape of the composite segment 100. Note that 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.

[0045] 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.

[0046] The joint plate 12 is formed in a plate shape and is made of a rectangular steel plate. The joint plate 12 is formed to extend in the axial direction AD and the radial direction RD. The joint plate 12 is spanned and fixed between both ends in the longitudinal direction 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.

[0047] The pair of joint plates 12 are joined to both ends in the circumferential direction CD of each of the pair of main girders 11. The joint plate 12 is arranged to cover an opening formed by the pair of main girders 11 and the skin plate 16 arranged between the pair of main girders 11 at both ends in the circumferential direction CD of the composite segment 100. The joint plate 12 is provided at both ends in the arc direction of the skin plate 16 to form the side surface of the composite segment 100 in the circumferential direction CD.

[0048] As shown in Fig. 3, at least one or more 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 arranged 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.

[0049] 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 at 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.

[0050] 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 in the synthetic segment 100 to expose the bolt hole 15 between the concrete 80 and the joint plate 12. The bolt box 82 serves as a working space for fastening bolts for fastening the joint plates 12 of the adjacent synthetic segments 100 in the circumferential direction CD.

[0051] 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, and may be performed by, for example, a one-touch joint, or other well-known techniques may also be used.

[0052] 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 with 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.

[0053] As shown in FIG. 5, the skin plate 16 is joined so as to close an opening at the end face on the base side of a frame body 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 body 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.

[0054] [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 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 separate.

[0055] 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. In the composite segment 100, the fixing member 20 protrudes from the steel shell 10 toward the inside of the concrete 80 and is joined to 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 bars 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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 to each other 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.

[0060] Since the first part 21 and the second part 22 are integrated and the fixing member 20 has high rigidity and a high bonding force 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.

[0061] 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.

[0062] FIG. 9 is an enlarged view of the fixing member 20 portion of the composite 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 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 distribution rib 48 is inserted into the first through hole 25, and the end portion of the first force distribution rib 48 is positioned inside the first through hole 25.

[0063] The fixing member 20 is disposed between a pair of main girders 11 arranged with their plate surfaces facing each other so as to face each other in the axial direction AD. In the axial direction AD, one end portion of the first force distribution rib 48 is connected to the first through hole 25 of the fixing member 20 provided on one of the main girders 11, and the other end portion of the first force distribution 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 distribution rib 48 are respectively connected to the fixing member 20. Note that the end portion of the first force distribution rib 48 and the fixing member 20 may be fixed by welding.

[0064] The first force distribution rib 48 connects two fixing members 20 arranged opposite to each other in a state where the concrete 80 is filled. The first force distribution 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 composite segment 100, the separation between the main girder 11 and the concrete 80 is suppressed by the first force distribution rib 48 connected to the main girder 11, and the concrete 80 and the main girder 11 are firmly fixed via the first force distribution rib 48 and the fixing member 20. The composite 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 distribution rib 48 is not provided, due to the first force distribution rib 48.

[0065] As in the case of the fixing member 20 of the modification shown in FIG. 8(c), at least one or more second through holes 26 may be formed in the second portion 22. Similar to the first portion 21, the second portion 22 serves as a PBL (Perfo - Bond Leisten) divel.

[0066] 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 number and may be plural. 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.

[0067] [Shape holding 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 holding member 23 is joined to the inner surface of the skin plate 16. The shape holding member 23 protrudes from the skin plate 16 in the radial direction RD.

[0068] The shape holding 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 holding 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 holding 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 holding member 23 can also be joined to both or one of the pair of main girders 11.

[0069] [Reinforcing rib 50] FIG. 11 is a perspective view, a side view, and a plan view of the steel shell 10 of the composite segment 100 according to Embodiment 1. FIG. 11(a) is a perspective view of the inside of the steel shell 10 viewed from the inside in the radial direction RD. FIG. 11(b) is a side view of the inside of the steel shell 10 viewed in the radial direction RD. FIG. 11(c) is a plan view of the inside of the steel shell 10 viewed in the axial direction AD. The composite segment 100 has at least one or more reinforcing ribs 50 inside the joint plate 12.

[0070] As shown in FIG. 11, the steel shell 10 is provided with at least one or more reinforcing ribs 50 that protrude inward from the pair of joint plates 12. The reinforcing ribs 50 are fixed and integrated with the concrete 80 and function as so-called anchors. In the composite segment 100, both sides of the reinforcing ribs 50 are firmly fixed by the concrete 80.

[0071] The reinforcing ribs 50 are provided so as to protrude from one joint plate 12 toward the other joint plate 12 on the inner surface of the pair of joint plates 12. More specifically, in the circumferential direction CD, the reinforcing ribs 50 are fixed to one of the pair of joint plates 12 and are provided on each of the pair of joint plates 12 so as to protrude from one joint plate 12 toward the other joint plate 12 on the inner surface of the pair of joint plates 12.

[0072] The reinforcing ribs 50 are fixed to the concrete 80 filled inside the frame body and the skin plate 16 composed of the pair of main girders 11 and the pair of joint plates 12, suppress the movement in the circumferential direction CD, and constitute a portion that resists the tensile force applied to the pair of joint plates 12.

[0073] The reinforcing ribs 50 are provided on the inner surface of the joint plate 12 and are welded to the inner surface of the joint plate 12. The reinforcing ribs 50 protrude from one of the joint plates 12 and are not connected to the other joint plate 12. That is, the tip of the protruding direction of the reinforcing rib 50 is fixed to the concrete 80 and is not connected to the other joint plate 12. In the composite segment 100, the reinforcing ribs 50 protrude from the steel shell 10 toward the inside of the concrete 80 and are combined with the concrete 80. The reinforcing ribs 50 are members that resist the tensile force applied to the joint plate 12 in the circumferential direction CD and reduce and eliminate the tensile force applied to the joint plate 12.

[0074] The reinforcing ribs 50 are provided on each of the pair of joint plates 12 so as to be paired at positions facing each other in the circumferential direction CD, for example. In one joint plate 12 of the steel shell 10 according to the first embodiment, the reinforcing ribs 50 are arranged at four positions along the axial direction AD. The quantity and positions of the reinforcing ribs 50 are not limited to the illustrated mode, and are determined in consideration of, for example, the size and shape of the composite segment 100 and the like.

[0075] FIG. 12 is an enlarged view of the installation portion of the reinforcing rib 50 of the composite segment 100 according to the first embodiment. FIG. 12(a) is a side view of the installation portion of the reinforcing rib 50 as viewed in the radial direction RD. FIG. 12(b) is a plan view of the reinforcing rib 50 as viewed in the axial direction AD. In FIG. 12, the broken-line plate-like portion indicates the joint plate 12 of the adjacent composite segment 100.

[0076] As shown in FIG. 12, at least one or more bolt holes 15 for connecting the left and right adjacent composite segments 100 arranged in the circumferential direction CD of the excavation hole are formed in the joint plate 12. The left and right adjacent composite segments 100 in the circumferential direction CD are connected by butting the joint plates 12 and fastening with fixtures 60 such as bolts and nuts inserted through the bolt holes 15. It is desirable that the reinforcing rib 50 be provided near the bolt hole 15 and the fixture 60 to which bolt tension is applied in the joint plate 12.

[0077] In order to correspond to the bolt tension related to the bolt hole 15 and the fixture 60, it is desirable that the reinforcing rib 50 be provided on both sides of the bolt hole 15 and the fixture 60 in the axial direction AD. That is, it is desirable that the composite segment 100 have a structure in which the bolt hole 15 and the fixture 60 are arranged between a pair of reinforcing ribs 50 arranged in the axial direction AD. Note that although it is desirable that the reinforcing rib 50 be provided on both sides of the bolt hole 15 and the fixture 60 in the axial direction AD, it may be provided on one side of the bolt hole 15 and the fixture 60.

[0078] As shown in FIGS. 11(b) and 12(a), the reinforcing rib 50 is a plate piece formed in a straight shape when viewed from the side in the radial direction RD with the main girder 11 facing downward. The reinforcing rib 50 is a plate-like member extending in the circumferential direction CD and the radial direction RD as shown in FIG. 12(b). The reinforcing rib 50 is, for example, a flat plate formed in a rectangular shape when viewed in the axial direction AD.

[0079] As shown in FIG. 11(c), the reinforcing rib 50 is not fixed to the skin plate 16, and a gap is formed between the reinforcing rib 50 and the skin plate 16 in the composite segment 100. Note that the configuration of the composite segment 100 is not limited to this configuration, and the reinforcing rib 50 and the skin plate 16 may be fixed.

[0080] As shown in FIG. 12(b), at least one or more through holes 55 are formed in the reinforcing rib 50. The through hole 55 is a hole penetrating in the plate thickness direction of the reinforcing rib 50 and is a hole penetrating in the axial direction AD. The reinforcing rib 50, for example, serves as a PBL (Perfo-Bond Leisten).

[0081] FIG. 13 is an enlarged view of the reinforcing rib 50 of a modified example of the composite segment 100 according to Embodiment 1. FIG. 13(a) is a plan view of the reinforcing rib 50 of the first modified example viewed in the axial direction AD. FIG. 13(b) is a plan view of the reinforcing rib 50 of the second modified example viewed in the axial direction AD. As shown in FIG. 13(a), the reinforcing rib 50 may be a ribbed steel plate having at least one or more ribs 58. The rib 58 is an elongated protruding portion. The rib 58 is provided on the plate surface of the reinforcing rib 50 facing the axial direction AD.

[0082] In FIG. 13(a), the rib 58 extends in the radial direction RD, but the configuration is not limited thereto, and it may be formed in other shapes such as being inclined with respect to the radial direction RD. Since the composite segment 100 has the rib 58, the concrete 80 is three-dimensionally restrained at these portions, so that a large shear resistance can be obtained and a resistance to the tensile force applied to the joint plate 12 can be obtained.

[0083] As shown in FIG. 13(b), the reinforcing rib 50 may be a corrugated steel plate having a plurality of convex portions 59. The convex portions 59 are provided on the plate surface facing the axial direction AD of the reinforcing rib 50. The pattern formed by the plurality of convex portions 59 shown in FIG. 13(b) is an example, and the reinforcing rib 50 may have at least one or more convex portions 59.

[0084] FIG. 13(b) shows an aspect in which the reinforcing rib 50 has a plurality of convex portions 59. However, if the strength can be ensured, the reinforcing rib 50 may have an aspect with a plurality of concave portions (not shown), or an aspect with both convex portions 59 and concave portions. By the reinforcing rib 50 having convex portions 59 or concave portions or the like, the concrete 80 is three-dimensionally constrained at these portions in the composite segment 100, so that a large shear resistance can be obtained and a resistance to the tensile force applied to the joint plate 12 can be obtained.

[0085] [Modification Example of Composite Segment 100] FIG. 14 is a schematic cross-sectional view showing the internal structure of a modification example of the composite segment 100 according to Embodiment 1. The reinforcing bar unit 40 used in the composite segment 100 can have its structure changed as appropriate. As an example, the reinforcing bar unit 40A shown in FIG. 14 has a shape in which the first force-bearing bars 48A extend linearly, and the ends 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.

[0086] Since the reinforcing bar unit 40A shown in FIG. 14 does not have a structure in which the first force-bearing bars 48A are inserted into the first through holes 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 bars 48A to the fixing member 20 by means such as welding.

[0087] FIG. 15 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 the fixing member 20 does not have the fixing member 20.

[0088] FIG. 16 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. 16, the steel shell 10 may not have the shape-retaining member 23.

[0089] [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 by joining a pair of main girders 11 and a pair of joint plates 12, and the skin plate 16 is disposed outside the frame 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.

[0090] 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.

[0091] In the step of installing the internal structure of the steel shell 10, a step of joining the fixing member 20 to the main girder 11 is performed. Also, a 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.

[0092] The shape-retaining member 23 is installed in alignment with the fixed 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 and the main girders 11 are installed with a gap therebetween. 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.

[0093] FIG. 17 is a perspective view of the state in which the reinforcing cage 41 is accommodated in the steel shell 10 shown in FIG. 10. After the steel shell 10 is assembled, the steel shell 10 is moved to, for example, a factory where concrete 80 is placed. Then, a 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 fixed members 20 of the steel shell 10.

[0094] The reinforcing cage 41 is placed on the shape-retaining member 23 installed inside the steel shell 10. Thereby, the second main reinforcing bars 43 and the second distribution reinforcing bars 45 of the reinforcing cage 41 are arranged at a distance from the skin plate 16. Thereby, the second main reinforcing bars 43 are arranged with an appropriate cover thickness inside the concrete 80 to be filled.

[0095] FIG. 18 is a perspective view of the state in which the first distribution reinforcing bars 48 are arranged in the steel shell 10 shown in FIG. 17. The first distribution reinforcing bars 48 are arranged after the reinforcing cage 41 is arranged at an appropriate position. The first distribution reinforcing bars 48 are arranged through the insertion portions 48a (see FIG. 7) at both ends into the first through holes 25 of the fixed members 20 arranged opposite to each other in the pair of main girders 11. In FIG. 7, the end of the main body portion 48b of the first distribution reinforcing bar 48 is placed on the upper surface of the first portion 21 of the fixed member 20, but the main body portion 48b may be placed on the reinforcing cage 41 and set such that there is a gap between the main body portion 48b and the first portion 21.

[0096] After the first shear reinforcement 48 is arranged, the first main reinforcement 42 of the reinforcing cage 41 and the first shear reinforcement 48 are joined. The joining is performed by welding, bundling with wire, or the like. The first shear reinforcement 48 and the reinforcing cage 41 can be joined in advance and installed in the steel shell 10 as the reinforcing unit 40. In the case of a structure in which the first shear reinforcement 48 is inserted into the first through hole 25 of the fixing member 20, in order to pass all the insertion portions 48a of the plurality of first shear reinforcements 48 through the first through hole 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 unit 40 without performing difficult alignment work by first installing the reinforcing cage 41 in the steel shell 10 and then installing the first shear reinforcement 48 in another process.

[0097] FIG. 19 is a perspective view of the steel shell 10 shown in FIG. 18 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 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 part of the steel shell 10. After the concrete 80 solidifies, the formwork is removed, and the composite segment 100 is completed.

[0098] [Effect of the composite segment 100 according to Embodiment 1] The composite segment 100 is fixed to one of the pair of joint plates 12 among the pair of joint plates 12, and is provided on each of the pair of joint plates 12 so as to protrude from one joint plate 12 toward the other joint plate 12 on the inner surface of the pair of joint plates 12. The reinforcing rib 50 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 to suppress the movement in the circumferential direction CD, and constitutes a portion that resists the tensile force applied to the pair of joint plates 12. The composite segment 100 has a strong bonding force with the concrete 80 due to the reinforcing rib 50, secures the pull-out resistance, and can resist the tensile force applied to the joint plate 12 in the circumferential direction CD of the tunnel. Therefore, even when the composite segment 100 does not have a vertical rib which is a plate-like member of a steel plate connecting the main girders 11, it can prevent the deformation of the joint plate 12 and the peeling of the concrete 80. Further, both surfaces of the reinforcing rib 50 of the composite segment 100 are firmly fixed by the concrete 80. Therefore, even when the composite segment 100 does not have a vertical rib which is a plate-like member of a steel plate connecting the main girders 11, it can prevent the deformation of the joint plate 12 and the peeling of the concrete 80.

[0099] The reinforcing rib 50 is a plate-like member extending in the circumferential direction CD and the radial direction RD, and at least one through hole 55 is formed in the reinforcing rib 50. Since the concrete 80 in the through hole 55 of the composite segment 100 is three-dimensionally constrained, a large shear resistance can be obtained by the reinforcing rib 50 having the through hole 55, and a resistance to the tensile force applied to the joint plate 12 can be obtained. The composite segment 100 can further resist the tensile force applied to the joint plate 12 as compared with the case where it does not have the through hole 55, due to the reinforcing rib 50 having the through hole 55. Therefore, even when the composite segment 100 does not have a vertical rib which is a plate-like member of a steel plate connecting the main girders 11, it can prevent the deformation of the joint plate 12 and the peeling of the concrete 80.

[0100] The reinforcing rib 50 has at least one or more ribs 58 which are elongated protruding parts, or at least one or more convex parts 59. Since the concrete 80 is three-dimensionally constrained by the ribs 58 in the composite segment 100, the reinforcing rib 50 having the ribs 58 can obtain a large shear resistance and can obtain a resistance to the tensile force applied to the joint plate 12. Also, since the concrete 80 is three-dimensionally constrained by the convex parts 59 in the composite segment 100, the reinforcing rib 50 having the convex parts 59 can obtain a large shear resistance and can obtain a resistance to the tensile force applied to the joint plate 12.

[0101] The composite segment 100 can further resist the tensile force applied to the joint plate 12 as compared with the case where it does not have the rib 58 or the convex part 59 by the reinforcing rib 50 having the rib 58 or the convex part 59. Therefore, even when the composite segment 100 does not have the longitudinal ribs which are plate-like members of the steel plate connecting the main girders 11 to each other, it can prevent the deformation of the joint plate 12 and prevent the peeling of the concrete 80.

[0102] The reinforcing rib 50 is provided on both sides of the bolt hole 15 of the joint plate 12 in the axial direction AD. Bolt tension is applied to the bolt hole 15 of the joint plate 12 by the force applied to the composite segment 100. Since the reinforcing rib 50 is provided on both sides of the bolt hole 15 of the joint plate 12 in the axial direction AD in the composite segment 100, the composite segment 100 can further resist the tensile force applied to the joint plate 12 as compared with the case where the reinforcing rib 50 is not provided on both sides of the bolt hole 15. Therefore, even when the composite segment 100 does not have the longitudinal ribs which are plate-like members of the steel plate connecting the main girders 11 to each other, it can prevent the deformation of the joint plate 12 and prevent the peeling of the concrete 80.

[0103] In addition, in the composite segment 100, since the reinforcing ribs 50 are provided on both sides of the bolt holes 15 of the joint plate 12 in the axial direction AD, the composite segment 100 can more evenly resist the tensile force applied to the joint plate 12 as compared with the case where the reinforcing ribs 50 are provided only on one side of the bolt holes 15. Therefore, even when the composite segment 100 does not have vertical ribs which are plate-shaped members of steel plates connecting the main girders 11 to each other, the deformation of the joint plate 12 can be prevented and the peeling of the concrete 80 can be prevented.

[0104] Embodiment 2. FIG. 20 is a partially enlarged view of the reinforcing rib 50A of the composite segment 100 according to Embodiment 2. FIG. 21 is a side view and a plan view of the reinforcing rib 50A of the composite segment 100 according to Embodiment 2. FIG. 20(a) is a side view of the reinforcing rib 50A as viewed in the radial direction RD. FIG. 20(b) is a partial side view of a modified example of the reinforcing rib 50A as viewed in the radial direction RD. FIG. 20(c) is a partial side view of another modified example of the reinforcing rib 50A as viewed in the radial direction RD. FIG. 21(a) is a side view of the reinforcing rib 50A as viewed in the circumferential direction CD. FIG. 21(b) is a side view of the reinforcing rib 50A as viewed in the radial direction RD. FIG. 21(c) is a plan view of the reinforcing rib 50A as viewed in the axial direction AD. FIG. 21(d) is a plan view of a modified example of the reinforcing rib 50A as viewed in the axial direction AD.

[0105] Components having the same functions and operations as those of the composite segment 100 according to Embodiment 1 are denoted by the same reference numerals and their descriptions are omitted. Hereinafter, with reference to FIGS. 20 and 21, the configuration of Embodiment 2 will be described focusing on the differences from Embodiment 1, and the configurations not described in Embodiment 2 are the same as those in Embodiment 1.

[0106] The reinforcing rib 50A of Embodiment 2 is a member having the same function as the reinforcing rib 50 of Embodiment 1. The shape of the reinforcing rib 50A of Embodiment 2 is different from that of the reinforcing rib 50 of Embodiment 1. The reinforcing rib 50A shown in FIGS. 20 and 21 is formed in a T shape when the side of the joint plate 12 is downward in the side view seen in the radial direction RD. The number and position of the reinforcing ribs 50A are determined in consideration of, for example, the size and shape of the composite segment 100. Note that the reinforcing rib 50A is not limited to the one in which the first portion 51A and the second portion 52A are formed in a T shape. For example, as shown in FIG. 20(b), in the reinforcing rib 50 of the modified example, the first portion 51A and the second portion 52A may be formed in an L shape. Further, as shown in FIG. 20(c), the reinforcing rib 50A may be formed in a cross shape at the first portion 51A and the second portion 52A.

[0107] As shown in FIG. 20, in order to cope with the bolt tension related to the bolt hole 15 and the fixture 60, it is desirable that the reinforcing rib 50A is provided on both sides of the bolt hole 15 and the fixture 60 in the axial direction AD. That is, it is desirable that the composite segment 100 has a structure in which the bolt hole 15 and the fixture 60 are arranged between a pair of reinforcing ribs 50A arranged in the axial direction AD. Note that although it is desirable that the reinforcing rib 50A is provided on both sides of the bolt hole 15 and the fixture 60 in the axial direction AD, it may be provided on one side of the bolt hole 15 and the fixture 60.

[0108] The reinforcing rib 50A includes a first portion 51A which is a plate-like portion arranged along the radial direction RD, and a second portion 52A which is a plate-like portion arranged along the axial direction AD at the tip of the protruding direction of the first portion 51A. More specifically, the first portion 51A is a plate-like member extending in the radial direction RD and the circumferential direction CD. The second portion 52A is a plate-like member extending in the axial direction AD and the radial direction RD. One plate surface of the second portion 52A faces the inner surface of one of the pair of joint plates 12 in the circumferential direction CD.

[0109] As shown in FIG. 21, the reinforcing rib 50A has a first portion 51A extending from the central portion of the second portion 52A whose plate surface is arranged along the axial direction AD to the joint plate 12 along the circumferential direction CD joined thereto. That is, in the reinforcing rib 50A, the base portion of the first portion 51A is joined to the joint plate 12, and the tip portion of the first portion 51A is joined to the second portion 52A. The reinforcing rib 50A may be formed by joining the first portion 51A and the second portion 52A by means such as welding, or a pre-integrally formed one may be used.

[0110] As in the case of the reinforcing rib 50A of the modification shown in FIG. 21(d), at least one or more first through holes 55A may be formed in the first portion 51A. The first portion 51A serves, for example, as a PBL (Perfo-Bond Leisten) divel.

[0111] The first portion 51A of the reinforcing rib 50A may have at least one or more ribs 58 (see FIG. 13(a)) which are elongated protruding portions, or at least one or more convex portions 59 (FIG. 13(b)).

[0112] [Effect of the composite segment 100 according to Embodiment 2] The reinforcing rib 50A includes a first portion 51A which is a plate-like member extending in the radial direction RD and the circumferential direction CD, and a second portion 52A which is a plate-like member extending in the axial direction AD and the radial direction RD.

[0113] The synthetic segment 100 has its bonding force with the joint plate 12 and the concrete 80 strengthened by the reinforcing rib 50A with the above structure provided on the joint plate 12, so that peeling from the concrete 80 is suppressed, and the concrete 80 and the joint plate 12 are firmly fixed via the reinforcing rib 50A. Further, the second portion 52A serves as a resistance when moving in the circumferential direction CD, and suppresses the movement of the reinforcing rib 50A in the circumferential direction CD. Therefore, the synthetic segment 100 can ensure the withdrawal resistance by the reinforcing rib 50A and can resist the tensile force applied to the joint plate 12 as compared with the case without the reinforcing rib 50A. By having the above structure, the synthetic segment 100 can prevent the deformation of the joint plate 12 and prevent the peeling of the concrete 80 even when there is no longitudinal rib which is a plate-shaped member of the steel plate connecting the main girders 11 to each other.

[0114] A first through hole 55A is formed in the first portion 51A of the reinforcing rib 50A. Since the concrete 80 in the first through hole 55A is three-dimensionally constrained, the synthetic segment 100 can obtain a large shear resistance by the reinforcing rib 50A having the first through hole 55A and can obtain a resistance to the tensile force applied to the joint plate 12. The synthetic segment 100 can further resist the tensile force applied to the joint plate 12 by the reinforcing rib 50A having the first through hole 55A as compared with the case without the first through hole 55A. Therefore, the synthetic segment 100 can prevent the deformation of the joint plate 12 and prevent the peeling of the concrete 80 even when there is no longitudinal rib which is a plate-shaped member of the steel plate connecting the main girders 11 to each other.

[0115] The reinforcing rib 50A has at least one or more ribs 58 which are elongated protruding portions, or at least one or more convex portions 59. The synthetic segment 100 can further resist the tensile force applied to the joint plate 12 by the reinforcing rib 50A having the rib 58 or the convex portion 59 as compared with the case without the rib 58 or the convex portion 59. Therefore, the synthetic segment 100 can prevent the deformation of the joint plate 12 and prevent the peeling of the concrete 80 even when there is no longitudinal rib which is a plate-shaped member of the steel plate connecting the main girders 11 to each other.

[0116] The reinforcing rib 50A is provided on both sides of the bolt hole 15 of the joint plate 12 in the axial direction AD. Since the reinforcing rib 50A of the composite segment 100 is provided on both sides of the bolt hole 15 of the joint plate 12 in the axial direction AD, the composite segment 100 can further resist the tensile force applied to the joint plate 12 as compared with the case where the reinforcing rib 50A is not provided on both sides of the bolt hole 15. Since the reinforcing rib 50A of the composite segment 100 is provided on both sides of the bolt hole 15 of the joint plate 12 in the axial direction AD, the composite segment 100 can resist the tensile force applied to the joint plate 12 in a more balanced manner as compared with the case where the reinforcing rib 50A is provided only on one side of the bolt hole 15. Therefore, even when the composite segment 100 does not have the vertical ribs which are plate-shaped members of the steel plate connecting the main girders 11 to each other, the deformation of the joint plate 12 can be prevented and the peeling of the concrete 80 can be prevented.

[0117] Embodiment 3. FIG. 22 is a partially enlarged view of the reinforcing rib 50B of the composite segment 100 according to Embodiment 3. FIG. 23 is a side view and a plan view of the reinforcing rib 50B of the composite segment 100 according to Embodiment 3. FIG. 24 is a plan view of the reinforcing rib 50B of a modified example of the composite segment 100 according to Embodiment 3. Note that FIG. 23(a) is a side view of the reinforcing rib 50B viewed in the circumferential direction CD. FIG. 23(b) is a side view of the reinforcing rib 50B viewed in the radial direction RD. FIGS. 23(c) and 24 are plan views of the reinforcing rib 50B viewed in the axial direction AD.

[0118] 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. 22 to 24, the configuration of Embodiment 3 will be described centering on the differences from Embodiment 1 and Embodiment 2. The configurations not described in Embodiment 3 are the same as those in Embodiment 1 and Embodiment 2.

[0119] The reinforcing rib 50B of Embodiment 3 is a member having the same function as the reinforcing rib 50 and the like of Embodiment 1. The reinforcing rib 50B of Embodiment 3 has a different configuration from that of the reinforcing rib 50B of Embodiment 1. The reinforcing rib 50B shown in FIGS. 22 to 24 has a first portion 51B and at least one or more anchor portions 57. The reinforcing rib 50B may be formed by joining the first portion 51B and the anchor portion 57 by means such as welding, or a pre-formed integral one may be used.

[0120] The first portion 51B is a plate piece formed in a straight shape when viewed from the side in the radial direction RD with the main girder 11 facing downward, and is a plate piece formed in an I shape when the joint plate 12 side is facing downward. The quantity and position of the first portion 51B are determined in consideration of, for example, the size and shape of the composite segment 100. The first portion 51B is a plate-like member extending in the radial direction RD and the circumferential direction CD.

[0121] The anchor portion 57 is combined with the concrete 80 and functions as a so-called anchor. The anchor portion 57 is a rod-shaped member. The anchor portion 57 has, for example, joints and is a reinforcing bar such as deformed steel bar. The anchor portion 57 is fixed to the plate surface of the first portion 51B facing the axial direction AD. The anchor portion 57 is arranged so as to extend in the circumferential direction CD. The anchor portion 57 is arranged so as to project from the tip of the first portion 51B and extend toward the center side of the composite segment 100 in the circumferential direction CD. The anchor portion 57 may be parallel to the circumferential direction CD or may be inclined with respect to the circumferential direction CD.

[0122] In FIG. 23, the reinforcing rib 50B has two anchor portions 57 arranged in the radial direction RD in the first portion 51B, but the number of the anchor portions 57 is not limited to two, and may be one or three or more. The quantity and position of the anchor portion 57 are determined in consideration of, for example, the size and shape of the composite segment 100.

[0123] Similar to the reinforcing rib 50B of the modification shown in FIG. 24, at least one or more first through holes 55B may be formed in the first portion 51B. The first portion 51B serves, for example, as a PBL (Perfo - Bond Leisten) girder.

[0124] As shown in FIG. 22, in order to withstand the bolt tension related to the bolt hole 15 and the fixture 60, the reinforcing rib 50B is preferably provided on both sides of the bolt hole 15 and the fixture 60 in the axial direction AD. That is, it is desirable that the composite segment 100 has a structure in which the bolt hole 15 and the fixture 60 are arranged between a pair of reinforcing ribs 50B arranged in the axial direction AD. Note that although the reinforcing rib 50B is preferably provided on both sides of the bolt hole 15 and the fixture 60 in the axial direction AD, it may be provided on one side of the bolt hole 15 and the fixture 60.

[0125] The first portion 51B of the reinforcing rib 50B may have at least one or more ribs 58 (see FIG. 13(a)), which are elongated protruding portions, or at least one or more convex portions 59 (FIG. 13(b)).

[0126] [Effect of the composite segment 100 according to Embodiment 3] The reinforcing rib 50B includes a first portion 51B, which is a plate - like member extending in the radial direction RD and the circumferential direction CD, and at least one or more anchor portions 57. The anchor portion 57 is a rod - shaped member fixed to the plate surface of the first portion 51B facing the axial direction AD, and is arranged so as to protrude and extend from the tip of the first portion 51B in the circumferential direction CD.

[0127] The synthetic segment 100 has its bonding strength with the concrete 80 enhanced by the reinforcing rib 50B with the above-described configuration provided on the joint plate 12, thus suppressing the peeling from the concrete 80, and the concrete 80 and the joint plate 12 are firmly fixed via the reinforcing rib 50B. Therefore, the synthetic segment 100 can secure the pull-out bearing capacity by the reinforcing rib 50B and can resist the tensile force applied to the joint plate 12 as compared with the case without the reinforcing rib 50B. Therefore, even when the synthetic segment 100 does not have the vertical rib which is a plate-shaped member of the steel plate connecting the main girders 11 to each other, it can prevent the deformation of the joint plate 12 and the peeling of the concrete 80.

[0128] A first through-hole 55B is formed in the first portion 51B of the reinforcing rib 50B. Since the concrete 80 in the first through-hole 55B is three-dimensionally constrained in the synthetic segment 100, a large shear bearing capacity can be obtained by the reinforcing rib 50B having the first through-hole 55B, and a resistance can be obtained against the tensile force applied to the joint plate 12. The synthetic segment 100 can further resist the tensile force applied to the joint plate 12 by the reinforcing rib 50B having the first through-hole 55B as compared with the case without the first through-hole 55B. Therefore, even when the synthetic segment 100 does not have the vertical rib which is a plate-shaped member of the steel plate connecting the main girders 11 to each other, it can prevent the deformation of the joint plate 12 and the peeling of the concrete 80.

[0129] The reinforcing rib 50B has at least one or more ribs 58 which are elongated protruding portions, or at least one or more convex portions 59. The synthetic segment 100 can further resist the tensile force applied to the joint plate 12 by the reinforcing rib 50B having the rib 58 or the convex portion 59 as compared with the case without the rib 58 or the convex portion 59. Therefore, even when the synthetic segment 100 does not have the vertical rib which is a plate-shaped member of the steel plate connecting the main girders 11 to each other, it can prevent the deformation of the joint plate 12 and the peeling of the concrete 80.

[0130] The reinforcing rib 50B is provided on both sides of the bolt hole 15 of the joint plate 12 in the axial direction AD. Since the reinforcing rib 50B is provided on both sides of the bolt hole 15 of the joint plate 12 in the axial direction AD, the composite segment 100 can resist the tensile force applied to the joint plate 12 more effectively compared to the case where the reinforcing rib 50B is not provided on both sides of the bolt hole 15. Since the reinforcing rib 50B is provided on both sides of the bolt hole 15 of the joint plate 12 in the axial direction AD, the composite segment 100 can resist the tensile force applied to the joint plate 12 in a more balanced manner compared to the case where the reinforcing rib 50B is provided only on one side of the bolt hole 15. Therefore, even when the composite segment 100 does not have the longitudinal ribs which are plate-shaped members of the steel plate connecting the main girders 11 to each other, it can prevent the deformation of the joint plate 12 and the peeling of the concrete 80.

[0131] Embodiment 4. FIG. 25 is a partially enlarged view of the reinforcing rib 50C of the composite segment 100 according to Embodiment 4. FIG. 26 is a side view and a plan view of the reinforcing rib 50C of the composite segment 100 according to Embodiment 4. FIG. 26(a) is a side view of the reinforcing rib 50C viewed in the circumferential direction CD. FIG. 26(b) is a side view of the reinforcing rib 50C viewed in the radial direction RD. FIG. 26(c) is a plan view of the reinforcing rib 50C viewed in the axial direction AD. FIG. 26(d) is a plan view of a modified example of the reinforcing rib 50C viewed in the axial direction AD.

[0132] 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. 25 and 26, 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.

[0133] The reinforcing rib 50C of Embodiment 4 is a member having the same function as the reinforcing rib 50 of Embodiment 1 and the like. The reinforcing rib 50C of Embodiment 4 has a different configuration from the reinforcing rib 50 of Embodiment 1 and the like. The reinforcing rib 50C shown in FIGS. 25 and 26 is formed in a U shape when the side view in the radial direction RD has the joint plate 12 side downward, and is formed in a U shape when the main girder 11 side is downward. The number and position of the reinforcing ribs 50C are determined in consideration of, for example, the size and shape of the composite segment 100 and the like.

[0134] The reinforcing rib 50C includes a first portion 51C that is a plate-like portion disposed on the joint plate 12 along the axial direction AD, and a pair of second portions 52C that are plate-like portions disposed along the radial direction RD at both ends of the first portion 51C in the axial direction AD. More specifically, the first portion 51C is a plate-like member extending in the axial direction AD and the radial direction RD. The second portion 52C is a plate-like member extending in the circumferential direction CD and the radial direction RD. One plate surface of the first portion 51C abuts against the inner surface of one of the pair of joint plates 12 in the circumferential direction CD.

[0135] The reinforcing rib 50C has a pair of second portions 52C extending from both ends of the first portion 51C whose plate surface is disposed along the axial direction AD toward the center side of the composite segment 100 along the circumferential direction CD joined to the first portion 51C. The reinforcing rib 50C may be formed by joining the first portion 51C and the second portion 52C by means such as welding, or a pre-formed integral one may be used.

[0136] A fixing through-hole 56C for inserting a fixture 60 for connecting the joint plates 12 of adjacent composite segments 100 is formed in the first portion 51C. As shown in FIG. 25, the fixture 60 is inserted into the fixing through-hole 56C. The fixture 60 is also inserted into the joint plates 12 of the composite segments 100 adjacent in the circumferential direction CD, and is used for fixing the joint plates 12 of the composite segments 100 adjacent in the circumferential direction CD. The fixture 60 is, for example, a bolt and a nut or the like. The reinforcing rib 50C is fixed to the joint plate 12 by the fixture 60.

[0137] As shown in Fig. 25, the reinforcing rib 50C does not need to be fixed to the joint plate 12 by welding, and is fixed to the joint plate 12 by a fixture 60 that fixes the joint plates 12 to each other when fixing the joint plates 12 of the synthetic segments 100 adjacent to each other in the circumferential direction CD. The reinforcing rib 50C is fixed to, for example, the bolt hole 15 or the like. Note that the fixing method of the reinforcing rib 50C is not limited to this method, and it may be fixed to the joint plate 12 by welding.

[0138] As shown in Fig. 26(d), at least one or more first through-holes 55C may be formed in the second portion 52C. The second portion 52C serves as, for example, a PBL (Perfo-Bond Leisten) divel.

[0139] Fig. 27 is a side view of the reinforcing rib 50C of another modified example of the synthetic segment 100 according to Embodiment 4. Fig. 27(a) is an example of a modified example of the reinforcing rib 50C, and Figs. 27(b) and 27(c) are examples of other modified examples of the reinforcing rib 50C.

[0140] As shown in Fig. 27, the reinforcing rib 50C may have a third portion 53C. The reinforcing rib 50C of the modified example includes a third portion 53C, which is a plate-like portion arranged along the axial direction AD at the tip of the protruding direction of the second portion 52C. The third portion 53C is a plate-like member extending in the axial direction AD and the radial direction RD. A part of one plate surface of the third portion 53C faces the inner surface of one of the pair of joint plates 12 in the circumferential direction CD. Also, another part of one plate surface of the third portion 53C faces the first portion 51C in the circumferential direction CD.

[0141] In the modified example of the reinforcing rib 50C shown in Fig. 27(a), when viewed in the radial direction RD, the portions of the second portion 52C and the third portion 53C are formed in a T shape. The modified example of the reinforcing rib 50C has T-shaped portions formed by the portions of the second portion 52C and the third portion 53C at both ends of the first portion 51C in the axial direction AD. That is, the reinforcing rib 50C has two T-shaped portions in the axial direction AD.

[0142] The reinforcing rib 50C is not limited to the case where the portions of the second part 52C and the third part 53C are formed in a T shape. For example, as shown in FIG. 27(b), in the reinforcing rib 50 of the modified example, the portions of the second part 52C and the third part 53C may be formed in an L shape. Further, as shown in FIG. 27(c), the reinforcing rib 50C may have the portions of the second part 52C and the third part 53C formed in a cross shape.

[0143] The second part 52C of the reinforcing rib 50C may have at least one or more ribs 58 (see FIG. 13(a)) which are elongated protrusion-shaped parts, or at least one or more convex parts 59 (FIG. 13(b)).

[0144] [Effect of the composite segment 100 according to Embodiment 4] The reinforcing rib 50C is formed in a U shape when viewed in the radial direction RD. The reinforcing rib 50C includes a first part 51C and a pair of second parts 52C. The first part 51C is a plate-like member extending in the axial direction AD and the radial direction RD, and one plate surface abuts against the inner surface of one of the pair of joint plates 12 in the circumferential direction CD. The second part 52C is a plate-like member extending in the circumferential direction CD and the radial direction RD, and is provided at both ends of the first part 51C in the axial direction AD. A fixing through-hole 56C for inserting a fixture 60 for connecting the joint plates 12 of adjacent composite segments 100 is formed in the first part 51C. The reinforcing rib 50C is fixed to the pair of joint plates 12 by the fixture 60.

[0145] The synthetic segment 100 has the bonding strength between the joint plate 12 and the concrete 80 enhanced by the reinforcing rib 50C configured as described above provided on the joint plate 12, so that peeling from the concrete 80 is suppressed, and the concrete 80 and the joint plate 12 are firmly fixed via the reinforcing rib 50C. Therefore, the synthetic segment 100 can secure the pull-out resistance force by the reinforcing rib 50C and can resist the tensile force applied to the joint plate 12 as compared with the case where the reinforcing rib 50C is not provided. Therefore, the synthetic segment 100 can prevent deformation of the joint plate 12 and prevent peeling of the concrete 80 even when it does not have a longitudinal rib which is a plate-shaped member of a steel plate connecting the main girders 11 to each other. Further, since the reinforcing rib 50C can be fixed to the joint plate 12 by the fixture 60, welding is not required for fixing the reinforcing rib 50C and the joint plate 12, and the assembling process of the synthetic segment 100 becomes easier as compared with the case where the reinforcing rib 50C is not provided.

[0146] The reinforcing rib 50C further includes a third portion 53C. The third portion 53C is a plate-shaped member extending in the axial direction AD and the radial direction RD, and a part of one plate surface faces the inner surface of one of the pair of joint plates 12 in the circumferential direction CD, and another part of one plate surface faces the first portion 51C.

[0147] The synthetic segment 100 has the bonding strength between the joint plate 12 and the concrete 80 enhanced by the reinforcing rib 50C configured as described above provided on the joint plate 12, so that peeling from the concrete 80 is suppressed, and the concrete 80 and the joint plate 12 are firmly fixed via the reinforcing rib 50C. Further, the third portion 53C serves as a resistance when moving in the circumferential direction CD and suppresses the movement of the reinforcing rib 50C in the circumferential direction CD. Therefore, the synthetic segment 100 can secure the pull-out resistance force by the reinforcing rib 50C and can resist the tensile force applied to the joint plate 12 as compared with the case where the reinforcing rib 50C is not provided. The synthetic segment 100 can prevent deformation of the joint plate 12 and prevent peeling of the concrete 80 even when it does not have a longitudinal rib which is a plate-shaped member of a steel plate connecting the main girders 11 to each other by having the above-described configuration.

[0148] Further, a first through hole 55C is formed in the second portion 52C of the reinforcing rib 50C. Since the concrete 80 in the first through hole 55C is three-dimensionally constrained in the composite segment 100, the reinforcing rib 50C having the first through hole 55C can provide a large shear strength and can resist the tensile force applied to the joint plate 12. The composite segment 100 can further resist the tensile force applied to the joint plate 12 by the reinforcing rib 50C having the first through hole 55C as compared with the case where it does not have the first through hole 55C. Therefore, even when the composite segment 100 does not have a longitudinal rib which is a plate-like member of a steel plate connecting the main girders 11, the deformation of the joint plate 12 can be prevented and the peeling of the concrete 80 can be prevented.

[0149] The reinforcing rib 50C has at least one or more ribs 58 which are elongated protruding portions, or at least one or more convex portions 59. The composite segment 100 can further resist the tensile force applied to the joint plate 12 by the reinforcing rib 50C having the rib 58 or the convex portion 59 as compared with the case where it does not have the rib 58 or the convex portion 59. Therefore, even when the composite segment 100 does not have a longitudinal rib which is a plate-like member of a steel plate connecting the main girders 11, the deformation of the joint plate 12 can be prevented and the peeling of the concrete 80 can be prevented.

[0150] Embodiment 5. FIG. 28 is a partially enlarged view of the reinforcing rib 50D of the composite segment 100 according to Embodiment 5. FIG. 29 is a side view and a plan view of the reinforcing rib 50D of the composite segment 100 according to Embodiment 5. FIG. 29(a) is a side view of the reinforcing rib 50D viewed in the circumferential direction CD. FIG. 29(b) is a side view of the reinforcing rib 50D viewed in the radial direction RD. FIG. 29(c) is a plan view of the reinforcing rib 50D viewed in the axial direction AD.

[0151] For components having the same functions and operations as the composite segment 100 according to Embodiments 1 to 4, the same reference numerals are given and their descriptions are omitted. Hereinafter, with reference to FIGS. 28 and 29, the configuration of Embodiment 5 will be described centering on the points different from Embodiments 1 to 4, and the configurations not described in Embodiment 5 are the same as those in Embodiments 1 to 4.

[0152] The reinforcing rib 50D of Embodiment 5 is a member having the same function as the reinforcing rib 50 etc. of Embodiment 1. The reinforcing rib 50D of Embodiment 5 has a different configuration from the reinforcing rib 50 of Embodiment 1. The reinforcing rib 50D shown in FIGS. 28 and 29 is formed in a U shape when the side view seen in the radial direction RD has the joint plate 12 side downward, and is formed in a U shape when the main girder 11 side is downward. The number and position of the reinforcing ribs 50D are determined in consideration of, for example, the size and shape of the composite segment 100.

[0153] The reinforcing rib 50D includes a first portion 51D which is a plate-like portion arranged on the joint plate 12 along the axial direction AD, and a pair of second portions 52D which are plate-like portions arranged along the radial direction RD at both ends of the first portion 51D in the axial direction AD. More specifically, the first portion 51D is a plate-like member extending in the axial direction AD and the radial direction RD. The second portion 52D is a plate-like member extending in the circumferential direction CD and the radial direction RD. One plate surface of the first portion 51D abuts on the inner surface of one of the pair of joint plates 12 in the circumferential direction CD.

[0154] The reinforcing rib 50D has a pair of second portions 52D extending from both ends of the first portion 51D whose plate surface is arranged along the axial direction AD toward the center side of the composite segment 100 along the circumferential direction CD joined to the first portion 51D. The reinforcing rib 50D may be formed by joining the first portion 51D and the second portion 52D by means such as welding, or a pre-integrally formed one may be used.

[0155] In the first part 51D, a fixing through-hole 56D is formed which serves the same role as the fixing through-hole 56C of the fourth embodiment. As shown in FIG. 28, a fixture 60 is inserted into the fixing through-hole 56D.

[0156] The reinforcing rib 50D has at least one or more anchor portions 57D in the second part 52D. The reinforcing rib 50D may be formed by joining the second part 52D and the anchor portion 57D by means such as welding, or a pre-integrally formed one may be used. The anchor portion 57D is a rod-shaped member and is the same member as the anchor portion 57 of the third embodiment.

[0157] The anchor portion 57D is fixed to the plate surface of the second part 52D facing the axial direction AD. The anchor portion 57D is arranged to extend in the circumferential direction CD. The anchor portion 57D is arranged to project from the tip of the second part 52D in the circumferential direction CD and extend toward the center side of the composite segment 100.

[0158] In FIG. 29, the reinforcing rib 50D in the second part 52D has two anchor portions 57D arranged in the radial direction RD. However, the number of the anchor portions 57D is not limited to two, and may be one or three or more. The quantity and position of the anchor portions 57D are determined in consideration of, for example, the size and shape of the composite segment 100.

[0159] FIG. 30 is a plan view of a reinforcing rib 50D of a modified example of the composite segment 100 according to the fifth embodiment. As in the case of the reinforcing rib 50D of the modified example shown in FIG. 30, at least one or more first through-holes 55D may be formed in the second part 52D. The second part 52D serves, for example, as a PBL (Perfo-Bond Leisten).

[0160] The second part 52D of the reinforcing rib 50D may have at least one or more ribs 58 (see FIG. 13(a)) which are elongated protruding portions, or at least one or more convex portions 59 (FIG. 13(b)).

[0161] [Effect of the composite segment 100 according to Embodiment 5] The reinforcing rib 50D is a rod-shaped member fixed to the plate surface of the second portion 52D facing the axial direction AD, and includes at least one or more anchor portions 57D arranged to protrude and extend from the tip of the second portion 52D in the circumferential direction CD.

[0162] In the composite segment 100, the bonding force between the joint plate 12 and the concrete 80 is strengthened by the reinforcing rib 50D having such a configuration, peeling from the concrete 80 is suppressed, and the concrete 80 and the joint plate 12 are firmly fixed via the reinforcing rib 50D. Therefore, the composite segment 100 can secure the pull-out resistance force by the reinforcing rib 50D and can resist the tensile force applied to the joint plate 12 as compared with the case where the reinforcing rib 50D is not provided. By having the above configuration, the composite segment 100 can prevent deformation of the joint plate 12 and peeling of the concrete 80 even when there is no vertical rib which is a plate-shaped member of the steel plate connecting the main girders 11 to each other. Further, since the reinforcing rib 50D can be fixed to the joint plate 12 by the fixture 60, welding is not required for fixing the reinforcing rib 50D and the joint plate 12, and the assembly process of the composite segment 100 becomes easier as compared with the case where the reinforcing rib 50D is not provided.

[0163] Further, a first through hole 55D is formed in the second portion 52D of the reinforcing rib 50D. In the composite segment 100, since the concrete 80 in the first through hole 55D is three-dimensionally constrained, a large shear resistance force can be obtained by the reinforcing rib 50D having the first through hole 55D, and a resistance force can be obtained against the tensile force applied to the joint plate 12. The composite segment 100 can further resist the tensile force applied to the joint plate 12 by the reinforcing rib 50D having the first through hole 55D as compared with the case where the first through hole 55D is not provided. Therefore, the composite segment 100 can prevent deformation of the joint plate 12 and peeling of the concrete 80 even when there is no vertical rib which is a plate-shaped member of the steel plate connecting the main girders 11 to each other.

[0164] The reinforcing rib 50D has at least one or more ribs 58 which are elongated protruding portions, or at least one or more convex portions 59. The composite segment 100 can resist the tensile force applied to the joint plate 12 more than when it does not have the rib 58 or the convex portion 59, due to the reinforcing rib 50D having the rib 58 or the convex portion 59. Therefore, even when the composite segment 100 does not have a longitudinal rib which is a plate-shaped member of a steel plate connecting the main girders 11 to each other, it can prevent the deformation of the joint plate 12 and prevent the peeling of the concrete 80.

[0165] [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 5 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 5.

[0166] 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 combination in the embodiments, and can be changed as appropriate. For example, the reinforcing rib 50 can also be used in combination with the reinforcing ribs 50A to 50D which are modification examples. Also, as a precaution, the scope of various changes, applications, and uses made by those skilled in the art as necessary is also included in the technical scope.

[0167] The composite segment 100 described above may also include combinations of the respective features shown in the following Supplementary Notes 1 to 14. The combinations are shown below. [Supplementary Note 1] A composite segment constituting a cylindrical body buried as an earth retaining structure, A pair of main girders extending in the circumferential direction of the cylindrical body and 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 cylindrical body with respect to the frame body composed of the pair of main girders and the pair of joint plates, In the circumferential direction, it is fixed to one of the pair of joint plates, and is provided on each of the pair of joint plates so as to protrude from one joint plate toward the other joint plate on the inner surface of the pair of joint plates. At least one or more reinforcing ribs that are fixed to the concrete filled inside the frame body and the skin plate to suppress movement in the circumferential direction and constitute a portion that resists the tensile force applied to the pair of joint plates, A composite segment comprising: [Appendix 2] The reinforcing rib is, A plate-like member extending in the circumferential direction and the radial direction, On the reinforcing rib, The composite segment according to Appendix 1, in which at least one or more through holes are formed. [Appendix 3] The reinforcing rib is, At least one or more ribs that are elongated protruding portions, or the composite segment according to Appendix 1 or 2 having at least one or more convex portions. [Appendix 4] The reinforcing rib is, A first portion that is a plate-like member extending in the radial direction and the circumferential direction, A second portion that is a plate-like member extending in the axial direction and the radial direction, The composite segment according to Appendix 1, comprising: [Appendix 5] The reinforcing rib is, A first portion that is a plate-like member extending in the radial direction and the circumferential direction, A rod-like member fixed to the plate surface of the first portion facing the axial direction, and at least one or more anchor portions arranged so as to protrude and extend from the tip of the first portion in the circumferential direction, The composite segment according to Appendix 1, comprising: [Appendix 6] In the first portion, a through hole is formed. The composite segment according to Appendix 4 or 5. [Appendix 7] The first part is at least one rib in the form of an elongated protruding part, or the composite segment according to any one of Appendices 4 to 6 having at least one convex part. [Appendix 8] On each of the pair of joint plates, at least one bolt hole is formed for connecting the circumferentially arranged synthetic segments adjacent to each other on the left and right, The reinforcing rib is the composite segment according to any one of Appendices 1 to 6 provided on both sides of the bolt hole in the axial direction. [Appendix 9] The reinforcing rib is formed in a U shape when viewed in the radial direction, a plate-like member extending in the axial direction and the radial direction, with one plate surface having a first part that abuts against the inner surface of one of the pair of joint plates in the circumferential direction, a plate-like member extending in the circumferential direction and the radial direction, and a pair of second parts provided at both ends of the first part in the axial direction, and includes In the first part, a fixing through hole is formed for inserting a fixture for connecting the joint plates of adjacent composite segments, The reinforcing rib is the composite segment according to Appendix 1 fixed to the pair of joint plates by the fixture. [Appendix 10] The reinforcing rib is a plate-like member extending in the axial direction and the radial direction, with a part of one plate surface facing the inner surface of one of the pair of joint plates in the circumferential direction, and further including a third part where another part of one plate surface faces the first part, which is the composite segment according to Appendix 9. [Appendix 11] The reinforcing rib is A rod-shaped member fixed to the axially facing plate surfaces of the pair of second parts, and having at least one anchor part arranged so as to project and extend from the tips of the pair of second parts in the circumferential direction. The composite segment according to appended note 9. [Appended note 12] The composite segment according to any one of appended notes 9 to 11, in which through holes are formed in each of the pair of second parts. [Appended note 13] In each of the pair of second parts, The composite segment according to any one of appended notes 9 to 12, having at least one or more ribs which are elongated protruding parts, or at least one or more convex parts. [Appended note 14] An earth retaining structure formed by combining a plurality of the composite segments according to any one of appended notes 1 to 13 in the circumferential direction and the axial direction.

Explanation of reference signs

[0168] 10 Steel shell, 11 Main girder, 12 Joint plate, 13 Bolt hole, 14 Boss, 15 Bolt hole, 16 Skin plate, 20 Fixing member, 21 First part, 22 Second part, 23 Shape retaining member, 23a End face, 25 First through hole, 26 Second through hole, 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, 50 Reinforcement rib, 50A Reinforcement rib, 50B Reinforcement rib, 50C Reinforcement rib, 50D Reinforcement rib, 51A First part, 51B First part, 51C First part, 51D First part, 52A Second part, 52C Second part, 52D Second part, 53C Third part, 55 Through hole, 55A First through hole, 55B First through hole, 55C First through hole, 55D First through hole, 56C Fixing through hole, 56D Fixing through hole, 57 Anchor part, 57D Anchor part, 58 Rib, 59 Protrusion, 60 Fixture, 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, AD Axial direction, CD Circumferential direction, RD Radial direction.

Claims

1. A synthetic 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 reinforcing ribs that are fixed to the concrete filled inside the frame body and the skin plate, are provided on each of the pair of joint plates so as to protrude from one joint plate toward the other joint plate on the inner surface of the pair of joint plates in the circumferential direction, suppress the movement in the circumferential direction, and constitute a portion that resists the tensile force applied to the pair of joint plates, A synthetic segment comprising the above.

2. The reinforcing rib is, a plate-like member extending in the circumferential direction and the radial direction, In the reinforcing rib, The synthetic segment according to claim 1, wherein at least one or more through holes are formed.

3. The reinforcing rib is, The synthetic segment according to claim 1 or 2, comprising at least one or more ribs that are elongated protruding portions, or at least one or more convex portions.

4. The reinforcing rib is, a first portion that is a plate-like member extending in the radial direction and the circumferential direction, a second portion that is a plate-like member extending in the axial direction and the radial direction, The synthetic segment according to claim 1, comprising the above.

5. The reinforcing rib is, a first portion that is a plate-like member extending in the radial direction and the circumferential direction, a rod-like member fixed to the plate surface facing the axial direction 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 circumferential direction, The synthetic segment according to claim 1, comprising the above.

6. The synthetic segment according to claim 4 or 5, wherein a through hole is formed in the first portion.

7. The first portion is, The synthetic segment according to claim 4 or 5, comprising at least one or more ribs that are elongated protruding portions, or at least one or more convex portions.

8. On each of the pair of joint plates, at least one or more bolt holes are formed for connecting synthetic segments adjacent to each other left and right in the circumferential direction, The reinforcing rib is, The composite segment according to any one of claims 1, 4, and 5, provided on both sides of the bolt hole in the axial direction.

9. The reinforcing rib is formed in a U-shape when viewed in the radial direction, a plate-like member extending in the axial direction and the radial direction, and one plate surface thereof has a first portion that abuts against the inner surface of one of the pair of joint plates in the circumferential direction, a plate-like member extending in the circumferential direction and the radial direction, and a pair of second portions provided at both ends of the first portion in the axial direction, and includes In the first portion, a fixing through hole is formed for inserting a fixture that connects the joint plates of adjacent composite segments. The reinforcing rib is The composite segment according to claim 1, fixed to the pair of joint plates by the fixture.

10. The reinforcing rib is a plate-like member extending in the axial direction and the radial direction, a part of one plate surface faces the inner surface of one of the pair of joint plates in the circumferential direction, and the composite segment according to claim 9, further including a third portion where another part of one plate surface faces the first portion.

11. The reinforcing rib is a rod-shaped member fixed to the plate surfaces of the pair of second portions facing the axial direction, and includes at least one or more anchor portions arranged to protrude and extend from the tips of the pair of second portions in the circumferential direction. The composite segment according to claim 9.

12. The composite segment according to any one of claims 9 to 11, in which through holes are formed in each of the pair of second portions.

13. In each of the pair of second portions, The composite segment according to any one of claims 9 to 11, having at least one or more ribs that are elongated protruding portions, or at least one or more convex portions.

14. An earth retaining structure formed by combining a plurality of the composite segments according to any one of claims 1, 4, 5, 9, 10, and 11 in the circumferential direction and the axial direction.

Images