Composite segments and earth retaining structures

Abstract

To provide a synthetic segment capable of improving the strength of the outer peripheral side of concrete filling the inside of a steel shell while maintaining the strength and rigidity of the steel shell, and an earth retaining structure.SOLUTION: The synthetic segment is a synthetic segment for constructing an earth-retaining structure by connecting multiple segments including a steel shell and concrete filling the inside of the steel shell in the circumferential direction and axial direction of the earth-retaining structure. The steel shell includes: a pair of main girders spaced apart in the axial direction; a skin plate joined to the outer peripheral side of the main girders; a pair of joint plates joined to both circumferential ends of the main girders; and a plurality of shape-retaining members joined between the pair of main girders and extending in the axial direction. The shape-retaining member has a concave shape that the central part in the axial direction of the side surface of the skin plate is concave from the outer circumference to the inner circumference of the earth-retaining structure, and an opening is formed between the skin plate and each shape-retaining member.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a composite segment that forms an earth retaining structure sunk into the ground, and to the earth retaining structure. [Background technology]

[0002] The Urban Ring Method (registered trademark) is a conventionally known method for press-in construction of earth-retaining structures to build vertical underground structures. In the Urban Ring Method, earth-retaining panels are assembled into a ring-shaped structure at the installation site, and the ring-shaped structure is pressed into the ground using a press-in device. After the ring-shaped structure is pressed into the ground, the inside of the ring-shaped structure is excavated and soil is removed, and a new ring-shaped structure is added on top of it. This work process is repeated up to a predetermined depth to construct an underground structure such as a shaft.

[0003] Another tunnel construction method is the shield tunneling method, in which a tunneling machine installed inside a vertical shaft excavates a certain distance, and then at the rear of the tunnel, a segment ring is constructed by assembling, for example, arc-shaped composite segments into a ring, and these are then successively extended to form a cylindrical lining, thereby constructing a shield tunnel.

[0004] Composite segments used in shafts or tunnels such as those described above are formed by filling a filler material such as concrete inside a steel shell having main girders that form the axial end faces of the earth-retaining structure, joint plates that form the circumferential end faces, and skin plates that form the outer peripheral surface, and then hardening the filler material (see, for example, Patent Document 1). Such composite segments can withstand earth pressure from the surrounding ground by ensuring strength and rigidity by integrally forming the steel shell and concrete. Furthermore, because composite segments are subject to tensile or compressive stress in the axial direction of the earth-retaining structure, shape-retaining members are provided inside the steel shell in a direction along the axial direction of the earth-retaining structure and are joined between the opposing main girders. The shape-retaining members stably maintain the dimensions of the steel shell between the main girders. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-047265 Summary of the Invention [Problem to be solved by the invention]

[0006] When shape-retaining members are provided, as in the composite segment of Patent Document 1, the strength and rigidity of the steel shell itself can be ensured, but the filled concrete between the shape-retaining members and located on the inner periphery of the shape-retaining members is displaced so that the concrete bulges out radially inward of the earth-retaining structure when subjected to the circumferential load of the earth-retaining structure. Therefore, in Patent Document 1, flanges are protruded in opposite directions from each of the pair of main girders to prevent the filled concrete from slipping, and reinforcing bars are placed inside the filled concrete located on the inner side of the earth-retaining structure relative to the shape-retaining members, extending circumferentially, to reinforce the concrete.

[0007] However, in the composite segment described in Patent Document 1, the filled concrete located on the outer periphery cannot be reinforced because a shape-retaining member is placed there, and there was a risk that the strength of the concrete on the outer periphery would be insufficient.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide a composite segment and an earth retaining structure that can improve the strength of the outer periphery of the concrete filled inside the steel shell while maintaining the strength and rigidity of the steel shell. [Means for solving the problem]

[0009] The composite segment according to the present invention is a composite segment that constructs an earth-retaining structure by being connected in multiple ways in the circumferential and axial directions of the earth-retaining structure, and comprises a steel shell and concrete filled inside the steel shell, wherein the steel shell has a pair of main girders spaced apart in the axial direction, a skin plate joined to the outer periphery of the main girders, a pair of joint plates joined to both ends of the main girders in the circumferential direction, and a plurality of shape-retaining members joined between the pair of main girders and extending in the axial direction, wherein each of the shape-retaining members has a concave shape in which a central portion in the axial direction of a side surface on the skin plate side is concave from the outer periphery side to the inner periphery side of the earth-retaining structure, and an opening is formed between the skin plate and each of the shape-retaining members, and an outer reinforcing bar is provided in the concrete, the outer reinforcing bar being made up of a plurality of main reinforcing bars extending in the circumferential direction and spaced apart in the axial direction, and a plurality of distribution reinforcing bars extending in the axial direction and spaced apart in the circumferential direction, the outer reinforcing bar being placed in the opening, and a tip end of the distribution reinforcing bar of the outer reinforcing bar being joined to the shape-retaining member. It is something.

[0010] The earth retaining structure according to the present invention is formed by combining a plurality of the above-described composite segments in the circumferential direction and the axial direction. [Effects of the Invention]

[0011] According to the composite segment of the present invention, each shape-retaining member has a concave shape in the axial center of its skin-plate-side side, recessed from the outer periphery toward the inner periphery of the earth-retaining structure, and an opening is formed between the skin plate and each shape-retaining member. Therefore, reinforcing bars consisting of main reinforcement and distribution reinforcement can be placed in the openings between the skin plate and the shape-retaining members, thereby improving the strength of the outer periphery of the concrete filled inside the steel shell. Furthermore, the openings between the skin plate and the shape-retaining members allow the concrete on both sides of the shape-retaining members to continue circumferentially through the openings, enabling smooth load transfer and achieving radial shear resistance of the earth-retaining structure. Furthermore, if multiple circumferentially extending shear-stop bars joined to the skin plate are installed in the openings between the skin plate and the shape-retaining members in the axial direction of the earth-retaining structure, the radial shear resistance of the earth-retaining structure can be improved. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a conceptual diagram of an earth retaining structure according to an embodiment. [Figure 2] FIG. 2 is a conceptual diagram of a segment ring according to an embodiment, viewed in the axial direction. [Figure 3] FIG. 2 is a perspective view schematically illustrating a composite segment according to an embodiment. [Figure 4] FIG. 2 is a perspective view of a steel shell of a composite segment according to an embodiment, as viewed from the inner periphery side. [Figure 5] FIG. 2 is a perspective view of a steel shell of a composite segment according to an embodiment, as viewed from the outer periphery side. [Figure 6] FIG. 2 is a schematic vertical cross-sectional view of a steel shell of a composite segment according to an embodiment, as viewed from the side. [Figure 7] FIG. 4 is a schematic vertical cross-sectional view of a steel shell according to a first modified example of the composite segment according to the embodiment, as viewed from the side. [Figure 8] FIG. 10 is a schematic vertical cross-sectional view of a steel shell according to a second modified example of the composite segment of the embodiment, as viewed from the side. DETAILED DESCRIPTION OF THE INVENTION

[0013] The composite segment according to the embodiment will be described below with reference to the drawings. Note that in the following drawings, including FIG. 1, the relative dimensional relationships and shapes of the components may differ from the actual ones. In the following drawings, the same reference numerals denote the same or equivalent components, and this applies throughout the entire specification. To facilitate understanding, terms indicating directions (e.g., up, down, left, right, front, rear, front and back, etc.) are used as appropriate, but these notations are for the convenience of explanation and do not limit the arrangement, direction or orientation of devices, instruments, parts, etc.

[0014] Embodiment [Earth retaining structure 200] Fig. 1 is a conceptual diagram of an earth-retaining structure 200 according to an embodiment. Note that, in Fig. 1, an axial direction AD represents the axial direction of the earth-retaining structure 200, and a circumferential direction CD represents the circumferential direction of the earth-retaining structure 200. Furthermore, a radial direction RD represents the radial direction of the earth-retaining structure 200, with the Y1 side representing the inner circumferential side of the earth-retaining structure 200 and the Y2 side representing the outer circumferential side of the earth-retaining structure 200.

[0015] The earth-retaining structure 200 is a structure used, for example, as an earth-retaining wall in the press-in caisson method, and is a structure that covers an excavated surface underground in construction methods such as the press-in method. The earth-retaining structure 200 is sunk into the ground. The earth-retaining structure 200 is formed in a cylindrical shape and has a hollow portion. The earth-retaining structure 200 has a plurality of segment rings 150, which are formed by connecting the plurality of segment rings 150 in succession in the direction in which the tunnel extends.

[0016] [Segment Ring 150] 2 is a conceptual diagram of a segment ring 150 according to an embodiment, viewed in the axial direction AD. The segment ring 150 is a structure that covers an excavation surface underground. The segment ring 150 is formed in an annular shape when viewed in the axial direction AD, and is formed in a cylindrical shape overall. The segment ring 150 is formed, for example, in a cylindrical shape, but is not limited to a cylindrical shape and may be an elliptical or rectangular shape when viewed in the axial direction.

[0017] The earth-retaining structure 200 is constructed by connecting a plurality of segment rings 150 in the direction in which the earth-retaining structure 200 extends, i.e., along the axial direction AD. When the earth-retaining structure 200 is used in a shield tunneling method, for example, the earth-retaining structure 200 is constructed by arranging the segment rings 150 one around the cross section of the tunnel (one ring). Therefore, the segment ring 150 constitutes one unit of the earth-retaining structure 200 in the direction in which the tunnel extends.

[0018] The segment ring 150 is divided into a plurality of combined segments 100 in the circumferential direction CD. That is, a plurality of combined segments 100 are arranged in a ring shape, and adjacent combined segments 100 are connected to each other to form the segment ring 150. Note that, although the segment ring 150 shown in FIG. 2 is illustrated as if the combined segments 100 are approximately equal in size in the circumferential direction CD, the combined segments 100 may be formed to have different sizes depending on their installation positions in the circumferential direction CD.

[0019] 1, in the earth-retaining structure 200, adjacent segment rings 150 in the axial direction AD are assembled in a state in which the composite segments 100 constituting the segment ring 150 are displaced in the circumferential direction CD. More specifically, in the earth-retaining structure 200, the composite segments 100 constituting the segment ring 150 are constructed in a staggered arrangement.

[0020] [Synthetic Segment 100] Fig. 3 is a perspective view schematically showing a composite segment 100 according to an embodiment. Fig. 4 is a perspective view of the steel shell 10 of the composite segment 100 according to an embodiment, as viewed from the inner peripheral side. Fig. 5 is a perspective view of the steel shell 10 of the composite segment 100 according to an embodiment, as viewed from the outer peripheral side. Fig. 6 is a schematic vertical cross-sectional view of the steel shell 10 of the composite segment 100 according to an embodiment, as viewed from the side.

[0021] The composite segments 100 are arranged in a ring shape and connected to each other in the circumferential direction CD to form a cylindrical segment ring 150 that covers the excavation surface underground. The segment rings 150 are also connected along the axial direction AD to construct the earth-retaining structure 200. In other words, the earth-retaining structure 200 is constructed by connecting multiple composite segments 100 in the circumferential direction CD and the axial direction AD.

[0022] The composite segment 100 is a box-shaped structure made by combining multiple steel materials. The composite 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.

[0023] In addition, the composite segment 100 has an arc-shaped steel shell 10 surrounded by five sides and open on the Y1 side in the radial direction RD, and concrete 80 as a filler filled inside it, and the steel shell 10 and the concrete 80 are integrated.

[0024] As shown in Figures 3 to 6, the steel shell 10 comprises a pair of main girders 11 made of steel plates formed in an arc shape along the circumferential direction CD, a skin plate 16 made of steel plate welded to the outer periphery of the pair of main girders 11, a pair of joint plates 12 made of steel plates formed in a rectangular shape and welded to both ends of the pair of main girders 11 and the skin plate 16, and a plurality of shape-retaining members 20 arranged at intervals in the circumferential direction CD between the pair of joint plates 12 and extending in the axial direction AD, and is open on the Y1 side (inner peripheral side) in the radial direction RD.

[0025] The skin plate 16 is formed in an arc shape when viewed in the axial direction AD and in a rectangular shape when viewed in the radial direction RD. The skin plate 16 forms the peripheral wall of the composite segment 100 when the steel shell 10 is installed underground.

[0026] The main girders 11 are provided at both ends of the skin plate 16 in the axial direction AD, i.e., at the upper and lower ends, and form the upper and lower surfaces of the steel shell 10. When the steel shell 10 is installed underground, the main girders 11 provided at the upper ends of the skin plates 16 form the ceiling wall of the composite segment 100, and the main girders 11 provided at the lower ends of the skin plates 16 form the bottom wall of the composite segment 100.

[0027] The joint plates 12 are provided at both ends of the skin plate 16 in the circumferential direction CD, i.e., at the left and right ends, and form the left and right sides of the steel shell 10. When the steel shell 10 is installed underground, the joint plates 12 provided at both ends of the skin plate 16 in the circumferential direction CD form the side walls of the composite segment 100.

[0028] The steel shell 10 is provided with a shape-retaining member 20 extending in the axial direction AD between a pair of main girders 11. A plurality of shape-retaining members 20 are provided at intervals in the circumferential direction CD and are arranged perpendicular to the pair of main girders 11. The shape-retaining member 20 is a plate-like member made of, for example, a steel plate. The central portion of the axial direction AD on the side surface of the skin plate 16 has a concave shape recessed from the Y2 side (outer circumferential side) to the Y1 side (inner circumferential side). An opening 60 is formed between the skin plate 16 and the shape-retaining member 20. However, the shape-retaining member 20 is not limited to a steel plate. The transverse dimension of the shape-retaining member 20 is shorter than the transverse dimension of the joint plate 12. The shape-retaining member 20 is provided to ensure the dimension between the main girders 11 during the fabrication of the composite segment 100.

[0029] In the illustrated example, the shape-retaining members 20 are arranged in pairs with a small gap between them in the circumferential direction CD, and three pairs of shape-retaining members 20 are arranged with a large gap between them in the circumferential direction CD. In other words, six shape-retaining members 20 are arranged with varying gaps between them in the circumferential direction CD. The shape-retaining members 20 do not have to be arranged in pairs with a small gap between them in the circumferential direction CD, and the shape and number of the shape-retaining members 20 are not limited to those in the illustrated example and are determined in consideration of, for example, the size and shape of the steel shell 10.

[0030] The main girders 11 are formed with a plurality of connecting holes 13 for connecting vertically adjacent steel shells 10 arranged in the axial direction AD. Vertically adjacent steel shells 10 are connected by butting the main girders 11 together and fastening the shanks of bolts inserted into the connecting holes 13 with nuts. Note that one-touch joints may be used instead of bolts and nuts as components for connecting vertically adjacent steel shells 10.

[0031] The joint plates 12 are formed with a plurality of connecting holes 14 for connecting adjacent steel shells 10 on the left and right in the circumferential direction CD. The adjacent steel shells 10 on the left and right are connected by butting the joint plates 12 together and fastening the shanks of bolts inserted into the connecting holes 14 with nuts.

[0032] The numbers of connecting holes 13, 14 shown in the drawings are merely examples and are not limited to the examples shown in the drawings. The numbers are determined taking into consideration the size and shape of the steel shell 10, for example.

[0033] A plurality of bolt boxes 81 are formed below the concrete 80 at intervals in the circumferential direction CD. These bolt boxes 81 are formed at positions corresponding to the connecting holes 13. After the steel shell 10 is filled with concrete 80, bolts can be inserted from the bolt boxes 81 into the connecting holes 13 and fastened with nuts. Furthermore, at both ends of the concrete 80 in the circumferential direction CD, a plurality of bolt boxes 82 are formed at intervals in the axial direction AD. These bolt boxes 82 are formed at positions corresponding to the connecting holes 14. After the steel shell 10 is filled with concrete 80, bolts can be inserted from the bolt boxes 82 into the connecting holes 14 and fastened with nuts.

[0034] Shear stop rebars 52 extending in the circumferential direction CD are provided on the inner surface of the skin plate 16. A plurality of these shear stop rebars 52 are provided in the opening 60 at intervals in the axial direction AD, and abut the inner surface of the skin plate 16, being welded at the abutting points. In the illustrated example, two shear stop rebars 52 are provided at intervals in the axial direction AD. The shear stop rebars 52 are concrete anchoring members that anchor the concrete 80 to the steel shell 10 and prevent the concrete 80 from peeling off from the steel shell 10. In other words, the shear stop rebars 52 strengthen the integration between the steel shell 10 and the concrete 80.

[0035] The shear stop rebars 52 do not have to be welded to all of the contact points with the skin plate 16, but may be welded to some of the contact points with the skin plate 16. The shape and number of the shear stop rebars 52 are not limited to the illustrated example, and are determined taking into consideration the size and shape of the steel shell 10, for example.

[0036] In this way, by providing the anti-slip rebars 52 on the inner surface of the skin plate 16, it is possible to suppress the concrete 80 from slipping toward the Y1 side (inner periphery) in the radial direction RD, which is the direction in which the concrete 80 peels off, thereby achieving a high anchoring effect for the concrete 80. Furthermore, by providing the anti-slip rebars 52, it is possible to improve the strength of the composite segment 100 against loads applied in the circumferential direction CD.

[0037] Furthermore, the concrete 80 is provided with inner reinforcing bars 40 arranged on the Y1 side (inner circumferential side) in the radial direction RD, and outer reinforcing bars 41 arranged on the Y2 side (outer circumferential side). Specifically, the outer reinforcing bars 41 are arranged in openings 60 formed between the shape-retaining member 20 and the skin plate 16, and the inner reinforcing bars 40 are arranged on the inner circumferential side of the shape-retaining member 20. In this way, the inner reinforcing bars 40 and the outer reinforcing bars 41 are arranged in the space within the steel shell 10 secured by abutting the shear stop bars 52 against the inner surfaces of the main girder 11 and the skin plate 16.

[0038] The inner reinforcing bars 40 are composed of multiple main reinforcements 42 arranged at intervals in the axial direction AD and extending in the circumferential direction CD, and multiple distribution reinforcements 44 arranged at intervals in the circumferential direction CD and extending in the axial direction AD. The main reinforcements 42 abut the distribution reinforcements 44 on the side opposite the skin plate 16, and the abutting points are joined to form an integrated structure. The distribution reinforcements 44 have L-shaped curved ends, sandwiching the multiple main reinforcements 42. The ends of the distribution reinforcements 44 are welded to the shape-retaining member 20. Joining the distribution reinforcements 44 to the shape-retaining member 20 in this manner improves resistance to abdominal pressure. Here, abdominal pressure refers to a secondary normal force acting toward the center of the cylindrical earth-retaining structure 200 when tensile force is generated in the main reinforcements 42 arranged in the earth-retaining structure 200 in a section where the cylindrical earth-retaining structure 200 is subjected to tension.

[0039] The outer reinforcing bars 41 are composed of a plurality of main reinforcements 43 arranged at intervals in the axial direction AD and extending in the circumferential direction CD, and a plurality of distribution reinforcements 45 arranged at intervals in the circumferential direction CD and extending in the axial direction AD. The main reinforcements 43 abut the side of the distribution reinforcements 45 opposite the skin plate 16, and the abutting points are joined together, integrating them. The distribution reinforcements 45 have linear tips that are welded to the shape-retaining member 20. Joining the distribution reinforcements 45 and the shape-retaining member 20 in this way improves resistance to abdominal pressure.

[0040] The main reinforcements 42, 43 do not have to be welded to the distribution reinforcements 44, 45 at all of their contact points, but may be welded to some of their contact points. Although the distribution reinforcement 44 has been described above as having an L-shaped curved tip, this is not limited to the illustrated example, and the tip may be straight. Although the distribution reinforcement 45 has been described as having a straight tip, this is not limited to the illustrated example, and the tip may be L-shaped. Although the main reinforcements 42, 43 have been described as contacting the side of the distribution reinforcement 44, 45 opposite the skin plate 16, this is not limited to the illustrated example, and the main reinforcement 42, 43 may be contacting the side of the distribution reinforcement 44, 45 facing the skin plate 16.

[0041] In the illustrated example, four main reinforcements 42, 43 are arranged at intervals in the axial direction AD. In addition, in the illustrated example, two distribution reinforcements 44 are arranged at offset positions in the axial direction AD, and these two are arranged in pairs with a small gap in the circumferential direction CD, and three pairs of distribution reinforcements 44 are arranged with a large gap in the circumferential direction CD. In addition, in the illustrated example, distribution reinforcements 45 are arranged in pairs with a small gap in the circumferential direction CD, and three pairs of distribution reinforcements 45 are arranged with a large gap in the circumferential direction CD. In other words, twelve distribution reinforcements 44 are arranged with varying gaps in the circumferential direction CD, and six distribution reinforcements 45 are arranged with varying gaps in the circumferential direction CD.

[0042] The inner reinforcing bars 40 and the outer reinforcing bars 41 are embedded and fixed in the concrete 80, thereby improving the strength of the concrete 80. The shapes and the number of the inner reinforcing bars 40 and the outer reinforcing bars 41 are not limited to the illustrated example, and are determined taking into consideration the size and shape of the composite segment 100, for example.

[0043] FIG. 7 is a schematic vertical cross-sectional view of a steel shell 10 according to a first modified example of the composite segment 100 of the embodiment, as viewed from the side.

[0044] In the first modified example of the embodiment, connecting rebars 46 are provided in the concrete 80 to connect the inner rebars 40 and the outer rebars 41. In the illustrated example, two connecting rebars 46 are provided at intervals in the axial direction AD, and six connecting rebars 46 are provided at intervals in the circumferential direction CD. The connecting rebars 46 surround the main rebars 42 on both sides of the inner rebar 40 in the axial direction AD and the main rebars 43 on both sides of the outer rebar 41 in the axial direction AD. In other words, the connecting rebars 46 straddle the main rebars 42, 43 in the radial direction RD, connecting the inner rebar 40 and the outer rebar 41 and maintaining their positions. In this way, the provision of connecting rebars 46 connecting the inner rebars 40 and the outer rebars 41 further improves the strength of the concrete 80. Note that the shape and number of connecting rebars 46 are not limited to those in the illustrated example, and any shape and number may be used as long as they can maintain the positions of the inner rebars 40 and the outer rebars 41. Furthermore, the connecting reinforcing bars 46 are described as connecting the inner reinforcing bars 40 and the outer reinforcing bars 41 and maintaining their positions by surrounding the main reinforcing bars 42 on both sides of the axial direction AD of the inner reinforcing bars 40 and the main reinforcing bars 43 on both sides of the axial direction AD of the outer reinforcing bars 41, but are not limited to the illustrated example. For example, any other structure may be used as long as it can maintain the positions of the inner reinforcing bars 40 and the outer reinforcing bars 41, such as connecting the main reinforcing bars 42 of the inner reinforcing bars 40 and the main reinforcing bars 43 of the outer reinforcing bars 41 with a steel wire.

[0045] FIG. 8 is a schematic vertical cross-sectional view of a steel shell 10 according to a second modified example of the composite segment 100 of the embodiment, as viewed from the side.

[0046] In the above, the outer reinforcing bars 41 are described as being composed of a plurality of main reinforcements 43 and a plurality of distribution reinforcements 45, but this is not limiting, and as shown in Fig. 8, the outer reinforcing bars 41 may be composed of only a plurality of main reinforcements 43. This is because the outer reinforcing bars 41 are arranged close to the skin plate 16, and the strength against the load applied in the circumferential direction CD by the distribution reinforcements 45 can be compensated for by the skin plate 16. However, providing the distribution reinforcements 45 can improve the strength against the load applied in the circumferential direction CD.

[0047] As described above, the composite segment 100 according to the embodiment is a composite segment 100 that is connected in multiple ways in the circumferential direction CD and the axial direction AD to construct an earth-retaining structure 200, and comprises a steel shell 10 and concrete 80 filled inside the steel shell 10, and the steel shell 10 has a pair of main girders 11 spaced apart in the axial direction AD, a skin plate 16 joined to the outer periphery of the main girders 11, a pair of joint plates 12 joined to both ends of the main girders 11 in the circumferential direction CD, and a plurality of shape-retaining members 20 joined between the pair of main girders 11 and extending in the axial direction AD, and each shape-retaining member 20 has a concave shape in which the central portion in the axial direction AD of the side surface of the skin plate 16 is concave from the outer periphery to the inner periphery of the earth-retaining structure 200, and an opening 60 is formed between the skin plate 16 and each shape-retaining member 20.

[0048] According to the composite segment 100 of the embodiment, each shape-retaining member 20 has a concave shape recessed from the outer periphery to the inner periphery of the earth-retaining structure 200 at the center in the axial direction AD of the skin plate 16-side side, and an opening 60 is formed between the skin plate 16 and each shape-retaining member 20. Therefore, reinforcing bars consisting of main reinforcement bars 43 and distribution bars 45 can be placed in the openings 60 between the skin plate 16 and the shape-retaining member 20, thereby improving the strength of the outer periphery of the concrete 80 filled inside the steel shell 10. Furthermore, the openings 60 between the skin plate 16 and the shape-retaining member 20 allow the concrete 80 on both sides of the shape-retaining member 20 to be continuous in the circumferential direction CD through the openings, enabling smooth load transmission and achieving a radial direction RD shear stop effect. Furthermore, if multiple shear stop reinforcing bars 52 extending in the circumferential direction CD and joining the skin plate 16 are provided in the openings 60 between the skin plate 16 and the shape-retaining member 20 in the axial direction AD, the shear stop effect in the radial direction RD can be improved.

[0049] In addition, in the composite segment 100 of the embodiment, inner reinforcing bars 40 and outer reinforcing bars 41 are provided within the concrete 80, each of which consists of a plurality of main reinforcements 42, 43 extending in the circumferential direction CD and spaced apart in the axial direction AD, and a plurality of distribution reinforcements 44, 45 extending in the axial direction AD and spaced apart in the circumferential direction CD, and the outer reinforcing bars 41 are arranged in the opening 60, and the inner reinforcing bars 40 are arranged closer to the inner periphery of the retaining structure 200 than the shape retention member 20.

[0050] According to the composite segment 100 of this embodiment, by placing an outer reinforcing bar 41 in the opening 60 between the skin plate 16 and the shape-retaining member 20, the strength of the outer periphery of the concrete 80 filled inside the steel shell 10 can be improved.

[0051] In the composite segment 100 according to the embodiment, a connecting reinforcing bar 46 that connects the inner reinforcing bar 40 and the outer reinforcing bar 41 is provided in the concrete 80 .

[0052] According to the composite segment 100 of the embodiment, the connecting reinforcing bars 46 that connect the inner reinforcing bars 40 and the outer reinforcing bars 41 are provided in the concrete 80. By doing so, the strength of the concrete 80 can be further improved.

[0053] In addition, in the composite segment 100 according to the embodiment, the steel shell 10 has shear stop bars 52 extending in the circumferential direction CD, and the shear stop bars 52 are arranged at intervals in the axial direction AD within the opening 60 and joined to the inner surface of the skin plate 16.

[0054] According to the composite segment 100 of the embodiment, by providing the anti-slip rebars 52 on the inner surface of the skin plate 16, it is possible to suppress the concrete 80 from slipping toward the Y1 side (inner periphery) in the radial direction RD, which is the direction in which the concrete 80 peels off, thereby achieving a high anchoring effect for the concrete 80. Furthermore, by providing the anti-slip rebars 52, it is possible to improve the strength of the composite segment 100 against a load applied in the circumferential direction CD. [Explanation of symbols]

[0055] 10 Steel shell, 11 Main girder, 12 Joint plate, 13 Connecting hole, 14 Connecting hole, 16 Skin plate, 20 Shape retaining member, 40 Inner rebar, 41 Outer rebar, 42 Main rebar, 43 Main rebar, 44 Distribution bar, 45 Distribution bar, 46 Connecting bar, 52 Shear stop bar, 60 Opening, 80 Concrete, 81 Bolt box, 82 Bolt box, 100 Composite segment, 150 Segment ring, 200 Earth retaining structure.

Claims

1. A composite segment that constructs an earth retaining structure by being connected in multiple circumferential and axial directions of the earth retaining structure, Steel shell and and concrete filled inside the steel shell, The steel shell comprises: A pair of main beams spaced apart in the axial direction; a skin plate joined to the outer periphery of the main girder; A pair of joint plates joined to both ends of the main girder in the circumferential direction; A plurality of shape-retaining members joined between the pair of main beams and extending in the axial direction, Each of the shape-retaining members is A central portion of the skin plate side surface in the axial direction has a concave shape that is concave from the outer circumferential side to the inner circumferential side of the earth retaining structure, An opening is formed between the skin plate and each of the shape-retaining members, The concrete contains: A plurality of main reinforcements extending in the circumferential direction and spaced apart in the axial direction; An outer reinforcing bar is provided, which is composed of a plurality of reinforcing bars extending in the axial direction and spaced apart in the circumferential direction, The outer reinforcing bar is disposed in the opening, The tip of the distribution bar of the outer reinforcing bar is joined to the shape-retaining member. Synthetic segment.

2. The concrete contains: A plurality of main reinforcements extending in the circumferential direction and spaced apart in the axial direction; An inner reinforcing bar is provided, which is composed of a plurality of distribution bars extending in the axial direction and spaced apart in the circumferential direction, The inner reinforcing bar is disposed on the inner circumferential side of the shape-retaining member. The synthetic segment of claim 1 .

3. The concrete contains: A connecting reinforcing bar is provided to connect the inner reinforcing bar and the outer reinforcing bar. The synthetic segment of claim 2 .

4. The steel shell comprises: A shear stop reinforcing bar extending in the circumferential direction is provided, The shear stop rebar is A plurality of the axially spaced axial grooves are provided in the opening and joined to the inner surface of the skin plate. A synthetic segment according to any one of claims 1 to 3.

5. A composite segment formed by combining a plurality of composite segments according to any one of claims 1 to 4 in the circumferential direction and the axial direction. Earth retaining structures.

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