Composite segments and earth retaining structures

Abstract

To provide a synthetic segment capable of preventing the displacement between a steel shell and concrete, and an earth retaining structure.SOLUTION: The synthetic segment is a synthetic segment for constructing an earth-retaining structure by connecting multiple segments in the circumferential direction and axial direction of the earth-retaining structure, which includes a steel shell and concrete filled inside the steel shell. The steel shell includes: a pair of main girders spaced apart in the axial direction; a skin plate joined to the outer circumference of the main girder; a pair of joint plates joined to both ends of the main girder in the circumferential direction; and a protruding plate that extends in the circumferential direction inside the steel shell and is formed with through-holes. The protruding plate protrudes from the steel shell into the concrete and engages with the concrete.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a synthetic segment used as an earth retaining structure such as a tunnel and an earth retaining structure.

Background Art

[0002] Conventionally, as a pressing method for an earth retaining structure for constructing a vertical underground structure, the Urban Ring method (registered trademark) is known. In the Urban Ring method, earth retaining panels are assembled into a ring-shaped structure at the sinking site, and the ring-shaped structure is pressed into the ground by a pressing device. Then, after the ring-shaped structure is pressed into the ground, the inside of the ring-shaped structure is excavated and the soil is discharged, and a new ring-shaped structure is added on top of it. By repeating such working steps to a predetermined depth, an underground structure such as a shaft is constructed.

[0003] Also, one of the tunnel construction methods is the shield method. The shield method is a method in which, every time a tunneling machine installed in a shaft is advanced by a certain length, an arc-shaped synthetic segment is assembled into a ring shape at the rear to construct a segment ring, and this is sequentially extended to form a cylindrical lining to construct a shield tunnel.

[0004] The synthetic segment used for a shaft or a tunnel as described above has a filling material such as concrete filled and hardened inside a steel shell having a main girder forming the axial end face of the earth retaining structure, a joint plate forming the circumferential end face, and a skin plate forming the outer peripheral surface (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] A composite segment integrates a steel shell with concrete filled inside the steel shell, thereby exhibiting the composite effect of steel and concrete. Therefore, it is desirable that the composite segment improves rigidity and load-bearing capacity by integrating the steel shell constituting the frame with the concrete filled inside the steel shell, preventing displacement between the steel shell and the concrete, and achieving a composite effect that allows it to behave as a whole against external forces. The invention in Patent Document 1 uses reinforcing members on the main girder to suppress the concrete from bulging inward, but the skin plate side, which is the outer circumference side of the composite segment, does not have a structure to suppress bulging. Therefore, depending on the size of the composite segment or the pressure applied to the composite segment, the invention in Patent Document 1 may not be able to suppress bulging due to displacement between the skin plate and the concrete, and there is a risk that displacement between the steel shell and the concrete may occur.

[0007] The present invention solves the above-mentioned problems and provides a composite segment and earth retaining structure that prevents displacement between a steel shell and concrete. [Means for solving the problem]

[0008] The composite segment according to the present invention is a composite segment that constructs an earth retaining structure by connecting multiple such segments in the circumferential and axial directions of the earth retaining structure, comprising a steel shell and concrete filled inside the steel shell, wherein the steel shell comprises a pair of main girders spaced apart in the axial direction, a skin plate joined to the outer circumference of the main girders, a pair of joint plates joined to both ends of the main girders in the circumferential direction, and inside the steel shell It protrudes from the main girder into the concrete interior, along the main girder. It extends in the circumferential direction, and the hole portion is a through hole. Multiple along the circumferential direction formed Concrete has entered multiple holes and is engaged with the concrete. It has a protruding plate, Within the concrete, there are main reinforcement bars extending in the circumferential direction and distribution reinforcement bars extending in the axial direction. There are inner reinforcement bars arranged on the inner circumference and composed of main reinforcement bars or main reinforcement bars and distribution reinforcement bars, outer reinforcement bars arranged on the outer circumference and composed of main reinforcement bars or main reinforcement bars and distribution reinforcement bars, and connecting reinforcement bars that connect the inner reinforcement bars and the protruding plate. The connecting reinforcement bars are bent at both ends to form a U-shape, with one end hooked onto the inner reinforcement bars and the other end inserted into some of the multiple holes. It is something that exists.

[0009] The earth retaining structure according to the present invention is formed by combining a plurality of the above-mentioned composite segments in the circumferential and axial directions. [Effects of the Invention]

[0010] The composite segment of the present invention has a protruding plate that extends circumferentially within the steel shell and has a through-hole formed therein. The protruding plate extends from the steel shell into the concrete and engages with the concrete. The composite segment can achieve a high anchoring effect of concrete to the steel shell by allowing concrete to fill the hole, thereby preventing displacement between the steel shell and the concrete. [Brief explanation of the drawing]

[0011] [Figure 1] This is a conceptual diagram of the earth retaining structure according to Embodiment 1. [Figure 2] This is a conceptual diagram of the segment ring according to Embodiment 1, viewed in the direction AD of the hole axis. [Figure 3] This is a perspective view of an example of a composite segment according to Embodiment 1, viewed from the inner circumference side. [Figure 4] This is a perspective view of an example of a composite segment according to Embodiment 1, seen from the outer periphery. [Figure 5] This is a perspective view showing an example of the internal structure of a synthetic segment according to Embodiment 1. [Figure 6] This is a side view showing an example of the internal structure of a synthetic segment according to Embodiment 1. [Figure 7] This is a cross-sectional view showing an example of the internal structure of a composite segment according to Embodiment 1. [Figure 8] This is a plan view of the protruding plate of the composite segment according to Embodiment 1, as seen in the direction AD of the hole axis. [Figure 9] This is a cross-sectional view showing an example of the internal structure of a first modified example of a synthetic segment according to Embodiment 1. [Figure 10] This is a cross-sectional view showing an example of the internal structure of a second modified example of the synthetic segment according to Embodiment 1. [Figure 11] This is a cross-sectional view showing an example of the internal structure of a third modified example of the synthetic segment according to Embodiment 1. [Figure 12] This is a cross-sectional view showing an example of the internal structure of a fourth modified example of the synthetic segment according to Embodiment 1. [Figure 13] It is a cross-sectional view showing an example of the internal structure of the composite segment according to Embodiment 2. [Figure 14] It is a cross-sectional view showing an example of the internal structure of the first modification of the composite segment 100 according to Embodiment 2. [Figure 15] It is a cross-sectional view showing an example of the internal structure of the second modification of the composite segment 100 according to Embodiment 2. [Figure 16] It is a cross-sectional view showing an example of the internal structure of the third modification of the composite segment 100 according to Embodiment 2.

Mode for Carrying Out the Invention

[0012] Hereinafter, the composite segment 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 ones, 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 easy understanding, but their notations are for convenience of explanation and do not limit the arrangement, direction, and orientation of the device, instrument, or component, etc.

[0013] Embodiment 1. [Earth retaining structure 200] FIG. 1 is a conceptual diagram of the earth retaining structure 200 according to Embodiment 1. Note that the hole axis direction AD shown in FIG. 1 represents the axial direction of the earth retaining structure 200, the circumferential direction CD represents the circumferential direction of the earth retaining structure 200, the radial direction RD represents the radial direction of the earth retaining structure 200, the Y1 side represents the inner circumferential side of the earth retaining structure 200, and the Y2 side represents the outer circumferential side of the earth retaining structure 200.

[0014] The earth retaining structure 200 is used as an earth retaining wall, for example, in 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 in tunnels that make up subways, road tunnels, water and sewage tunnels, power and communication tunnels, utility tunnels, etc., or in shafts, etc. The earth retaining structure 200 may also be used as an earth retaining wall in the press-in caisson method. When the earth retaining structure 200 is used as an earth retaining wall in the press-in caisson method, the earth retaining structure 200 covers the excavated surface underground in the press-in method or other construction methods and is sunk into the ground.

[0015] The earth retaining structure 200 is formed in a cylindrical shape and has a hollow portion. When the earth retaining structure 200 is used as an earth retaining wall in the press-in caisson method, the earth retaining structure 200 is positioned underground so that the axial direction AD of the cylindrical hole is in the vertical direction.

[0016] The earth retaining structure 200 is formed in a circular shape when viewed in the direction AD of the hole axis, and is formed in a cylindrical shape overall, but is not limited to a cylindrical shape. The earth retaining structure 200 may be formed in other shapes, such as an oval shape, an oval shape, or a square shape with rounded corners, when viewed in the direction AD of the hole axis. The earth retaining structure 200 has at least one segment ring 150, or has multiple segment rings 150, and the multiple segment rings 150 are connected continuously in the direction in which the tunnel extends.

[0017] [Segment Ring 150] Figure 2 is a conceptual diagram of the segment ring 150 according to Embodiment 1, viewed in the direction of the borehole axis AD. The segment ring 150 is a structure that covers the excavated surface underground. The segment ring 150 is formed in an annular shape when viewed in the direction of the borehole axis AD, and is formed in a cylindrical shape overall. The segment ring 150 is formed in a cylindrical shape, for example, but is not limited to a cylindrical shape.

[0018] The earth retaining structure 200 is constructed by connecting multiple segment rings 150 along the direction in which the earth retaining structure 200 extends, that is, along the bore axis direction AD. Alternatively, the earth retaining structure 200 may be composed of a single segment ring 150. When the earth retaining structure 200 is used, for example, in a shield tunneling method, the earth retaining structure 200 is constructed by arranging the segment rings 150 around the entire circumference (one ring) of the tunnel's cross-section. Therefore, in the earth retaining structure 200, the segment ring 150 constitutes one unit in the direction in which the tunnel extends.

[0019] The segment ring 150 is divided into multiple composite segments 100 in the circumferential direction CD. That is, multiple composite segments 100 are arranged in a ring, and adjacent composite segments 100 are connected to each other to form the segment ring 150. In Figure 2, the segment ring 150 is shown with composite segments 100 of approximately equal size in the circumferential direction CD, but the size of the composite segments 100 may be different depending on their installation position in the circumferential direction CD.

[0020] As shown in Figure 1, in the earth retaining structure 200, the segment rings 150 adjacent to each other in the hole axis direction AD are assembled in a state where the positions of the composite segments 100 constituting the segment rings 150 are shifted in the circumferential direction CD. More specifically, in the earth retaining structure 200, the composite segments 100 constituting the segment rings 150 are constructed in a staggered arrangement.

[0021] [Composite Segment 100] Figure 3 is a perspective view of an example of the composite segment 100 according to Embodiment 1, viewed from the inner circumference. Figure 4 is a perspective view of an example of the composite segment 100 according to Embodiment 1, viewed from the outer circumference. Figure 5 is a perspective view showing an example of the internal structure of the composite segment 100 according to Embodiment 1. Figure 6 is a side view showing an example of the internal structure of the composite segment 100 according to Embodiment 1. Figure 7 is a cross-sectional view showing an example of the internal structure of the composite segment 100 according to Embodiment 1. In order to explain the internal structure of the composite segment 100, the illustration of all concrete 80 is omitted in Figure 5, and the illustration of the right half of the concrete 80 is omitted in Figure 6. Figure 7 is a cross-sectional view shown by line AA in Figure 6. The composite segment 100 will be explained using Figures 3 to 7.

[0022] The composite segments 100 are arranged in a ring and connected to each other in the circumferential direction CD, forming a cylindrical segment ring 150 that covers the excavated surface underground. Multiple composite segments 100 are connected to the retaining structure 200 in the circumferential direction CD and the bore axis direction AD, thereby constructing the retaining structure 200. The composite segment 100 is a box-shaped structure made by combining multiple steel materials. When viewed in the bore axis direction AD of the segment ring 150, the composite segment 100 is formed in an arc shape, and the overall shape is curved.

[0023] The composite segment 100 has a steel shell 10 and concrete 80 filled inside the steel shell 10. The composite segment 100 is a composite structure of a box-shaped steel shell 10 and concrete 80 filled inside the steel shell 10 as a filler, and the steel shell 10 and concrete 80 are integrated into one structure.

[0024] Furthermore, the composite segment 100 has multiple main reinforcements 42 within the concrete 80, each extending in the circumferential direction CD and spaced apart in the bore axis direction AD. The number of main reinforcements 42 is not limited to multiple, but may be one. Furthermore, the composite segment 100 has multiple main reinforcements 43 within the concrete 80, each extending in the circumferential direction CD and spaced apart in the bore axis direction AD. The number of main reinforcements 43 is not limited to multiple, but may be one. Furthermore, the composite segment 100 has multiple distribution reinforcements 44 within the concrete 80, each extending in the bore axis direction AD and spaced apart in the circumferential direction CD. The number of distribution reinforcements 44 is not limited to multiple, but may be one. Furthermore, the composite segment 100 has multiple distribution reinforcements 45 within the concrete 80, each extending in the bore axis direction AD and spaced apart in the circumferential direction CD. The number of muscle groups 45 that distribute force is not limited to multiple; it can be one or the same.

[0025] Furthermore, the composite segment 100 has a protruding plate 30 that protrudes into the interior of the steel shell 10. The composite segment 100 may also have connecting reinforcing bars 50 that connect to the protruding plate 30 (see Figure 9).

[0026] As shown in Figure 5, the steel shell 10 of the composite segment 100 has a pair of arc-shaped main girders 11 spaced apart in the hole axis direction AD, a skin plate 16 joined to the outer circumference of the main girders 11, and a pair of joint plates 12 joined to both ends of the main girders 11 in the circumferential direction CD. The steel shell 10 is formed in a box shape by welding and fixing these main girders 11, joint plates 12, and skin plate 16 to each other to form a single unit.

[0027] The pair of main girders 11 are the parts where adjacent composite segments 100 abut each other in the hole axis direction AD of the earth retaining structure 200 and the segment ring 150, and are the parts where adjacent composite segments 100 are connected to each other. The pair of main girders 11 are located at both ends of the composite segment 100 in the hole axis 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 hole axis direction AD of the earth retaining structure 200 and the segment ring 150, and form one face and the other face of the composite segment 100 in the hole axis direction AD.

[0028] The main girder 11 is formed in a flat plate shape. The main girder 11 is formed in an arc shape in a plan view in the direction AD of the borehole axis, according to the cross-sectional shape of the tunnel, and is formed in an annular fan shape. The main girder 11 is formed to extend in the circumferential direction CD and the radial direction RD.

[0029] One of the pair of main girders 11 has multiple bolt holes 13 formed in it for connecting adjacent composite segments 100 stacked vertically in the hole axis direction AD. The number of bolt holes 13 is not limited to multiple; it may be one. For example, one bolt hole 13 is formed in each interval partitioned by the shape-retaining material 20. Also, as shown in Figure 3, bolt boxes 81 are provided in the concrete 80 at locations corresponding to the bolt holes 13. The bolt boxes 81 form a space in the composite segment 100 between the concrete 80 and the main girder 11 that exposes the bolt holes 13. The bolt boxes 81 serve as a working space used for fastening bolts to fasten the main girders 11 of adjacent composite segments 100 together in the hole axis direction AD.

[0030] Of the pair of main girders 11, the other main girder 11 has multiple bosses 14 formed thereon for connecting adjacent composite segments 100 stacked vertically in the hole axis direction AD. The number of bosses 14 is not limited to multiple; it may be one. The bosses 14 have mounting holes with internal threads for threading bolts.

[0031] Adjacent composite segments 100 in the hole axis direction AD are connected by butting the main girder 11 together, utilizing the bolt box 81, and fastening the shaft portion of the bolt, which is inserted through the bolt hole 13, with a nut, using bolts provided on the boss 14. The number of bolt holes 13 and bosses 14 is not limited to the illustrated example and is determined by considering, for example, the size and shape of the composite segment 100. Note that the connection of adjacent composite segments 100 in the hole axis direction AD is not limited to a structure connected by bolts and nuts, but may also be done by, for example, a one-touch joint, or by using other well-known techniques.

[0032] The pair of joint plates 12 are the parts where adjacent composite segments 100 come into contact with each other in the circumferential direction CD of the earth retaining structure 200 and the segment ring 150, and are the parts where adjacent composite segments 100 are connected. The pair of joint plates 12 are members attached to both ends of the composite segment 100 in the circumferential direction CD.

[0033] The joint plate 12 is formed in a plate shape and consists of a rectangular steel plate. The joint plate 12 is formed to extend in the direction AD in the hole axis direction and in the radial direction RD. The joint plate 12 is spanned and fixed between the longitudinal ends of a pair of main girders 11. The longitudinal direction of the main girders 11 is the circumferential direction CD. Joints may be attached to the ends of the composite segments 100 on which the joint plate 12 is located, for connecting the composite segments 100 together to form a single segment ring 150.

[0034] The joint plate 12 is positioned at both ends of the circumferential CD of the composite segment 100 so as to cover the opening formed by the pair of main girders 11 and the skin plate 16 positioned between the pair of main girders 11. The joint plate 12 is provided at both ends of the skin plate 16 in the arc direction and forms the left and right sides of the composite segment 100.

[0035] As shown in Figure 3, the joint plate 12 has multiple bolt holes 15 formed therein for connecting adjacent composite segments 100 arranged in the circumferential direction CD of the excavated hole. The number of bolt holes 15 is not limited to multiple; it may be one. Also, as shown in Figure 3, bolt boxes 82 are provided in the concrete 80 at locations corresponding to the bolt holes 15. The bolt boxes 82 form a space in the composite segment 100 between the concrete 80 and the joint plate 12 that exposes the bolt holes 15. The bolt boxes 82 serve as a working space used for fastening bolts to connect the joint plates 12 of adjacent composite segments 100 in the circumferential direction CD.

[0036] Adjacent composite segments 100 in the circumferential CD direction are connected by butting joint plates 12 together and fastening the shafts of bolts inserted through bolt holes 15 with nuts. The number of bolt holes 15 shown in the illustration is an example and is not limited to this, and is determined by considering, for example, the size and shape of the composite segments 100. Note that the connection of adjacent composite segments 100 in the circumferential CD direction is not limited to a structure connected by bolts and nuts, but may also be done by, for example, a one-touch joint, or by using other well-known techniques.

[0037] The skin plate 16 is a plate-shaped member facing the ground side of the composite segment 100, and is formed by bending a rectangular steel plate into an arc shape in the planar direction. The skin plate 16 is formed in a plate shape with a curved surface. The skin plate 16 is formed to extend in the circumferential direction CD and the hole axis direction AD. The skin plate 16 is formed in an arc shape when viewed in a plan view in the hole axis direction AD, and in a rectangular shape when viewed in a side view in the radial direction RD.

[0038] As shown in Figure 5, the skin plate 16 is joined to close the opening on the ground-side end face of the frame obtained by joining a pair of main girders 11 and a pair of joint plates 12. That is, the skin plate 16 is attached to the outer periphery of the main girders 11 and joint plates 12 that constitute the composite segment 100. When the composite segment 100 is installed in the ground, the skin plate 16 faces the wall of the excavation hole and constitutes the outer periphery wall of the earth retaining structure 200.

[0039] The steel shell 10 is joined between a pair of main girders 11 and may have multiple shape-retaining members 20 extending in the hole axis direction AD. The number of shape-retaining members 20 is not limited to multiple, and may be one. The shape-retaining members 20 are provided to ensure the dimensions between the main girders 11 during the manufacturing of the composite segment 100. It is desirable for the composite segment 100 to have shape-retaining members 20 from the viewpoint of strengthening pressure resistance or from a manufacturing viewpoint, but it is not necessary to have shape-retaining members 20 in relation to other internal structures that constitute the composite segment 100.

[0040] The shape-retaining member 20 is a member that extends in the direction AD of the hole axis. The shape-retaining member 20 is erected in the direction normal to the surface of the main girder 11 and the skin plate 16, and the end of the shape-retaining member 20 is joined to the main girder 11 in the direction AD of the hole axis. The shape-retaining member 20 is composed of a plate-shaped member made of, for example, a steel plate as shown in the figure, or a rod-shaped member made of a reinforcing bar (not shown) or the like.

[0041] In the illustrated example, the shape-retaining members 20 are arranged in pairs with small gaps between them in the circumferential direction CD, and three pairs of shape-retaining members 20 are arranged with large gaps between them in the circumferential direction CD. In other words, six shape-retaining members 20 are arranged in the circumferential direction CD with large and small gaps between them. The shape, number, and position of the shape-retaining members 20 are not limited to the illustrated example and can be determined by considering, for example, the size and shape of the composite segment 100.

[0042] In the composite segment 100 according to this embodiment, the shape-retaining material 20 is provided such that a gap 60 is formed between it and the skin plate 16. The outer reinforcing bars 41, described later, are placed in the gap 60, and the inner reinforcing bars 40, described later, are placed on the inner circumference side of the shape-retaining material 20. However, depending on the positional relationship with the outer reinforcing bars 41, the shape-retaining material 20 may be joined to the skin plate 16, and a gap 60 may not be formed between the shape-retaining material 20 and the skin plate 16.

[0043] The composite segment 100 has internal reinforcement bars 40 and external reinforcement bars 41 within the concrete 80. The internal reinforcement bars 40 are arranged on the inner circumference within the concrete 80 and consist of multiple main reinforcement bars 42, or multiple main reinforcement bars 42 and multiple distribution reinforcement bars 44. The external reinforcement bars 41 are arranged on the outer circumference within the concrete 80 and consist of multiple main reinforcement bars 43, or multiple main reinforcement bars 43 and multiple distribution reinforcement bars 45. Note that the number of main reinforcement bars 42, main reinforcement bars 43, distribution reinforcement bars 44, and distribution reinforcement bars 45 constituting the internal reinforcement bars 40 and external reinforcement bars 41 is not limited to multiple, but may be one or more.

[0044] Main reinforcement bars 42 and 43 are embedded inside the concrete 80 as main steel materials and are arranged to extend in the circumferential direction CD of the composite segment 100. Main reinforcement bars 42 are reinforcement bars located on the inner circumference side (Y1 side) of the radial direction RD and are also called inner reinforcement bars 40. Multiple main reinforcement bars 42 are provided along the hole axis direction AD of the segment ring 150. Main reinforcement bars 43 are reinforcement bars located on the outer circumference side of the radial direction RD and are also called outer reinforcement bars 41. Multiple main reinforcement bars 43 are provided along the hole axis direction AD of the segment ring 150.

[0045] In the example composite segment 100 shown in Figure 5, there are four main reinforcement bars 42 along the hole axis AD and one along the radial direction RD, and four main reinforcement bars 43 along the hole axis AD and one along the radial direction RD. However, the number of main reinforcement bars 42 and 43 is not limited to these numbers. Furthermore, the composite segment 100 may have other main reinforcement bars arranged between the main reinforcement bars 42 and 43 so as to extend in the circumferential direction CD of the composite segment 100.

[0046] The reinforcement bars 44 and 45 are embedded inside the concrete 80 and are arranged to extend in the axial direction AD of the hole in the composite segment 100. The reinforcement bars 44 are located on the inner circumference (Y1 side) in the radial direction RD and are also called inner reinforcement bars 40. Multiple reinforcement bars 44 are provided along the circumferential direction CD of the segment ring 150. The reinforcement bars 45 are located on the outer circumference (Y2 side) in the radial direction RD and are also called outer reinforcement bars 41. Multiple reinforcement bars 45 are provided along the circumferential direction CD of the segment ring 150.

[0047] Multiple distribution reinforcement bars 44 are provided in the direction in which the main reinforcement bars 42, which have a circumferential direction CD, extend. Similarly, multiple distribution reinforcement bars 45 are provided in the direction in which the main reinforcement bars 43, which have a circumferential direction CD, extend. The composite segment 100 shown in Figure 5 has six distribution reinforcement bars 44 and six distribution reinforcement bars 45 along the circumferential direction CD, but the number of distribution reinforcement bars 44 and 45 is not limited to this number.

[0048] The distribution reinforcement bars 44 may be formed in a U-shape with both ends bent, thereby restraining multiple main reinforcement bars 42. In the illustrated example, the distribution reinforcement bars 44 surround and restrain the main reinforcement bars 42 from the inner circumference side (Y1 side) in the radial direction RD. Note that the shape of the distribution reinforcement bars 44 is not limited to this shape, and may be formed in a straight line, for example.

[0049] The reinforcement bars 45 are formed in a straight line so as to extend in the direction AD of the hole axis. However, the shape of the reinforcement bars 44 is not limited to this shape, and for example, both ends may be bent and folded into a U-shape.

[0050] The distribution reinforcement bars 44 and 45 may also be parts of hoop reinforcement formed to extend radially RD and in the bore axis direction AD of the composite segment 100. In this case, the distribution reinforcement bar 44 is the inner circumference (Y1 side) of the hoop reinforcement, and the distribution reinforcement bar 45 is the outer circumference (Y2 side) of the hoop reinforcement.

[0051] The positional relationship between the main reinforcement 42 and the distribution reinforcement 44, and the positional relationship between the main reinforcement 43 and the distribution reinforcement 45, in the radial direction RD of the composite segment 100 are not limited. For example, the main reinforcement 42 may be located on the outer circumference side (Y2 side) relative to the distribution reinforcement 44, or the main reinforcement 42 may be located on the inner circumference side (Y1 side) relative to the distribution reinforcement 44. Similarly, the main reinforcement 43 may be located on the outer circumference side (Y2 side) relative to the distribution reinforcement 45, or the main reinforcement 43 may be located on the inner circumference side (Y1 side) relative to the distribution reinforcement 45.

[0052] The main reinforcement bars 42 and the distribution reinforcement bars 44 are engaged and may be welded to each other. Alternatively, the main reinforcement bars 42 and the distribution reinforcement bars 44 are engaged and may be tightly connected to each other with iron wire such as binding wire. The main reinforcement bars 43 and the distribution reinforcement bars 45 are engaged and may be welded to each other. Alternatively, the main reinforcement bars 43 and the distribution reinforcement bars 45 are engaged and may be tightly connected to each other with iron wire such as binding wire.

[0053] [Concrete 80 shear prevention structure] (Protruding plate 30) The composite segment 100 has a protruding plate 30. The protruding plate 30 is provided on the inside of the steel shell 10. The protruding plate 30 extends in the circumferential direction CD inside the steel shell 10, and a plurality of holes 31 are formed along the circumferential direction CD. The number of holes 31 is not limited to a plurality, but may be one. The protruding plate 30 protrudes from the steel shell 10 into the concrete 80 and engages with the concrete 80. In the composite segment 100 according to Embodiment 1, the protruding plate 30 is provided on the inner surface side (Y1 side) of the skin plate 16 in the radial direction RD. The number of protruding plates 30 provided on the skin plate 16 may be one or a plurality.

[0054] Figure 8 is a plan view of the protruding plate 30 of the composite segment 100 according to Embodiment 1, viewed in the direction AD of the hole axis. The protruding plate 30 is made of a flat steel material and is formed to extend circumferentially in the direction CD along the skin plate 16 and radially in the direction RD from the skin plate 16 toward the center of the segment ring 150. The protruding plate 30 is welded and fixed to the inner surface of the skin plate 16.

[0055] The protruding plate 30 is, for example, a PBL (Perfo-Bond Leisten) dowel. The protruding plate 30 has a plurality of holes 31 formed along its longitudinal direction, which is the circumferential direction CD. The holes 31 form holes that penetrate the protruding plate 30 in the hole axis direction AD. The holes formed by the holes 31 are circular holes, but the shape of the holes is not limited to circular holes and may be of other shapes. In the composite segment 100, the holes 31 of the protruding plate 30 function as a shear stopper between the protruding plate 30 and the concrete 80.

[0056] If the composite segment 100 has a shape-retaining material 20, the tip of the protruding plate 30 may be brought into contact with the shape-retaining material 20. Alternatively, the tip of the protruding plate 30 in the protruding direction may be joined to the shape-retaining material 20. In the radial direction RD, bringing the tip of the protruding plate 30 into contact with the edge of the shape-retaining material 20 can improve the strength of the composite segment 100 against abdominal pressure.

[0057] The protruding plate 30 and the shape-retaining material 20 may be joined by welding or other means, or they may not be joined by welding or other means. When the protruding plate 30 and the shape-retaining material 20 are joined by welding or other means, even greater strength can be ensured compared to when they are not joined.

[0058] Here, "internal pressure" refers to a secondary normal force directed toward the center of the retaining structure 200 when tensile force is generated in the main reinforcement bars placed in the retaining structure 200 in a section of the retaining structure 200 that is subjected to positive bending. In other words, "internal pressure" refers to a secondary normal force directed toward the center of the retaining structure 200 when tensile force is generated in the main reinforcement bars placed in the retaining structure 200 in a section of the retaining structure 200 that is subjected to tension.

[0059] (Connected reinforcing bars 50) Figure 9 is a cross-sectional view showing an example of the internal structure of a first modified example of the composite segment 100 according to Embodiment 1. The composite segment 100 may have connecting reinforcement bars 50, as shown in Figure 9. The connecting reinforcement bars 50 are reinforcement bars that bridge the inner reinforcement bars 40 and the protruding plate 30. The connecting reinforcement bars 50 are also reinforcement bars that connect the inner reinforcement bars 40 and the protruding plate 30. Here, the inner reinforcement bars 40 to which the connecting reinforcement bars 50 are connected are main reinforcement bars 42 arranged on the inside (Y1 side) in the radial direction RD. The inner reinforcement bars 40 to which the connecting reinforcement bars 50 are connected may also be connected to distribution reinforcement bars 44 arranged on the inside (Y1 side) in the radial direction RD.

[0060] The connecting reinforcing bar 50 is a reinforcing bar that extends radially RD in the composite segment 100. The connecting reinforcing bar 50 is bent at both ends and is formed in a U-shape overall. The connecting reinforcing bar 50 is bent at both ends and is formed so that both ends extend in the hole axis direction AD. Because the connecting reinforcing bar 50 is formed in a U-shape, when the composite segment 100 is manufactured, one end of the connecting reinforcing bar 50 is hooked onto the inner reinforcing bar 40 and the other end is inserted into the hole 31 of the protruding plate 30, thereby engaging the connecting reinforcing bar 50 with the inner reinforcing bar 40 and the protruding plate 30. Therefore, because the connecting reinforcing bar 50 is formed in a U-shape, it is easier to install the connecting reinforcing bar 50 inside the steel shell 10, and the manufacturing of the composite segment 100 is facilitated.

[0061] The connecting reinforcing bars 50, the inner reinforcing bars 40, and the protruding plates 30 are not joined by welding or the like. When concrete 80 is poured into the steel shell 10 and the concrete 80 hardens, the connecting reinforcing bars 50, the inner reinforcing bars 40, and the protruding plates 30 are joined together. However, the connecting reinforcing bars 50, the inner reinforcing bars 40, and the protruding plates 30 may be joined by welding or the like before the concrete 80 is poured.

[0062] The connecting reinforcing bar 50 shown in Figure 9 is an example of a U-shaped structure, but the shape of the connecting reinforcing bar 50 is not limited as long as it connects the inner reinforcing bar 40 and the protruding plate 30. For example, the connecting reinforcing bar 50 may be formed in a straight line in the middle and bent so that both ends face in opposite directions. Alternatively, the connecting reinforcing bar 50 may be formed in a straight line and both ends may be joined to the inner reinforcing bar 40 and the protruding plate 30 by welding or the like. Furthermore, the connecting reinforcing bar 50 may be rod-shaped or plate-shaped.

[0063] In the illustrated example, two connecting reinforcing bars 50 are arranged with an interval between them in the hole axis direction AD. The number of connecting reinforcing bars 50 installed in the hole axis direction AD is not limited to the illustrated example and is determined by considering, for example, the size and shape of the composite segment 100. Similarly, the number of connecting reinforcing bars 50 installed in the circumferential direction CD is determined by considering, for example, the size and shape of the composite segment 100.

[0064] [Effects of synthetic segment 100] The composite segment 100 extends circumferentially in the CD direction within the steel shell 10 and has a protruding plate 30 with a through-hole 31 formed therein. The protruding plate 30 protrudes from the steel shell 10 into the concrete 80 and engages with the concrete 80. The composite segment 100 can achieve a high anchoring effect of the concrete 80 to the steel shell 10 by allowing the concrete 80 to fill the hole 31, thereby preventing displacement between the steel shell 10 and the concrete 80.

[0065] Furthermore, the steel shell 10 has a shape-retaining member 20 joined between a pair of main girders. Therefore, the composite segment 100 can have its strength improved by the shape-retaining member 20, and the dimensions between the main girders 11 can be ensured during the manufacturing of the composite segment 100.

[0066] Furthermore, the tip of the protruding plate 30 is joined to the shape-retaining material 20 in the protruding direction. The composite segment 100 can be strengthened against abdominal pressure by the joining of the tip of the protruding plate 30 and the shape-retaining material 20 in the radial direction RD.

[0067] Furthermore, the composite segment 100 is provided with main reinforcement extending in the circumferential direction CD and distribution reinforcement extending in the bore axis direction AD within the concrete 80. By having this configuration, the composite segment 100 can improve the strength of the concrete 80.

[0068] Furthermore, the composite segment 100 is provided with an inner reinforcing bar 40, which is arranged on the inner circumference side and consists of main reinforcement bars 42, or main reinforcement bars 42 and distribution reinforcement bars 44, and an outer reinforcing bar 41, which is arranged on the outer circumference side and consists of main reinforcement bars 43, or main reinforcement bars 43 and distribution reinforcement bars 45. The composite segment 100 can improve the strength of the concrete 80 by having this configuration.

[0069] Furthermore, the composite segment 100 has connecting reinforcing bars 50 within the concrete 80 that connect the internal reinforcing bars 40 and the protruding plate 30. By having the connecting reinforcing bars 50, the composite segment 100 can improve its strength against the internal pressure applied to the earth retaining structure 200. In other words, the composite segment 100 can achieve both the shear prevention of the concrete 80 by having the protruding plate 30 and the improvement of strength against internal pressure by having the connecting reinforcing bars 50 that utilize the protruding plate 30.

[0070] Furthermore, the connecting reinforcing bars 50 are bent at both ends to form a U-shape, with one end of the connecting reinforcing bar 50 hooked onto the inner reinforcing bar 40 and the other end inserted through the hole 31 of the protruding plate 30. As a result, the U-shape of the connecting reinforcing bars 50 makes it easier to install the connecting reinforcing bars 50 inside the steel shell 10 during the manufacturing of the composite segment 100, thereby facilitating the manufacturing of the composite segment 100.

[0071] Furthermore, the protruding plate 30 is provided on the skin plate 16. Because the protruding plate 30 is provided on the skin plate 16, it is easier to install the protruding plate 30 on the bottom side of the skin plate 16 during the manufacturing of the composite segment 100, making the manufacturing of the composite segment 100 easier compared to when the protruding plate 30 is provided on another part. In addition, because the protruding plate 30 is provided on the skin plate 16, the rigidity of the skin plate 16 is increased, and the pressure resistance strength of the composite segment 100 can be strengthened.

[0072] Furthermore, since the earth retaining structure 200 has composite segments 100, the effects of the composite segments 100 described above can be realized.

[0073] In addition, the composite segment 100 of the first modified example has outer reinforcement bars 41, but the outer reinforcement bars 41 may not be necessary depending on the strength required by the composite segment 100 or the size of the composite segment 100. Also, as shown in Figure 9, the composite segment 100 of the first modified example has both main reinforcement bars 42 and distribution reinforcement bars 44 as inner reinforcement bars 40. However, the composite segment 100 of the first modified example may have only one of the main reinforcement bars 42 or distribution reinforcement bars 44, depending on the strength required by the composite segment 100 or the size of the composite segment 100.

[0074] Figure 10 is a cross-sectional view showing an example of the internal structure of a second modified example of the composite segment 100 according to Embodiment 1. As shown in Figure 10, the composite segment 100 may be installed by welding the main reinforcement bars 43 of the outer reinforcement bars 41 to the skin plate 16. Figure 11 is a cross-sectional view showing an example of the internal structure of a third modified example of the composite segment 100 according to Embodiment 1. As shown in Figure 11, the composite segment 100 may not have a shape-retaining material 20, depending on the strength required of the composite segment 100, or the size of the composite segment 100.

[0075] Figure 12 is a cross-sectional view showing an example of the internal structure of a fourth modified example of the composite segment 100 according to Embodiment 1. As shown in Figure 12, the composite segment 100 does not necessarily have inner reinforcement bars 40 and outer reinforcement bars 41, in relation to the strength required of the composite segment 100 or the size of the composite segment 100.

[0076] Embodiment 2. Figure 13 is a cross-sectional view showing an example of the internal structure of the composite segment 100 according to Embodiment 2. Components having the same function and operation as those in the composite segment 100 according to Embodiment 1 are denoted by the same reference numerals and their descriptions are omitted. Hereinafter, using Figure 13, Embodiment 2 will be described focusing on the differences between Embodiment 2 and Embodiment 1, while components not described in Embodiment 2 are the same as those in Embodiment 1.

[0077] (Protruding plate 30a) The composite segment 100 has a protruding plate 30a. The protruding plate 30a is provided on the inside of the steel shell 10. In the composite segment 100, the protruding plate 30a protrudes from the steel shell 10 toward the interior of the concrete 80 and engages with the concrete 80. In the composite segment 100 according to Embodiment 2, the protruding plate 30a is provided on the inner surface side of the main girder 11 in the hole axis direction AD. The number of protruding plates 30a provided on the main girder 11 may be one or multiple.

[0078] The protruding plate 30a is made of a flat steel plate and extends circumferentially in the direction CD along the main girder 11. The protruding plate 30a also protrudes from one main girder 11 toward the other main girder 11 in a pair of main girders 11. The protruding plate 30a is welded and fixed to the inner surface of the main girder 11.

[0079] The protruding plate 30a is, for example, a PBL (Perfo-Bond Leisten) dowel. The protruding plate 30a has multiple holes 31a formed along its longitudinal direction, which is the circumferential direction CD. The number of holes 31a is not limited to multiple, but may be one. The holes 31a form holes that penetrate the protruding plate 30a in the radial direction RD. The holes formed by the holes 31a are circular holes, but the shape of the holes is not limited to circular holes, and may be of other shapes. The composite segment 100 uses the holes 31a of the protruding plate 30a as a shear stopper between the protruding plate 30a and the concrete 80.

[0080] (Connected reinforcing bars 50a) Figure 14 is a cross-sectional view showing an example of the internal structure of a first modified example of the composite segment 100 according to Embodiment 2. The composite segment 100 may have connecting reinforcement bars 50a, as shown in Figure 14. The connecting reinforcement bars 50a are reinforcement bars that bridge the inner reinforcement bars 40 and the protruding plate 30a. The connecting reinforcement bars 50a are also reinforcement bars that connect the inner reinforcement bars 40 and the protruding plate 30a. Here, the inner reinforcement bars 40 to which the connecting reinforcement bars 50a connect are main reinforcement bars 42 arranged on the inside (Y1 side) in the radial direction RD. The inner reinforcement bars 40 to which the connecting reinforcement bars 50a connect may also be connected to distribution reinforcement bars 44 arranged on the inside (Y1 side) in the radial direction RD.

[0081] The connecting reinforcing bar 50a is a reinforcing bar that extends in the hole axis direction AD in the composite segment 100. The connecting reinforcing bar 50a is bent at both ends and is formed in a U-shape overall. The connecting reinforcing bar 50a is bent at both ends and is formed so that both ends extend in the radial direction RD. Because the connecting reinforcing bar 50a is formed in a U-shape, one end of the connecting reinforcing bar 50a is hooked onto the inner reinforcing bar 40 and the other end is inserted into the hole 31a of the protruding plate 30a, thereby engaging the connecting reinforcing bar 50a with the inner reinforcing bar 40 and the protruding plate 30a. Therefore, because the connecting reinforcing bar 50a is formed in a U-shape, it becomes easier to install the connecting reinforcing bar 50a inside the steel shell 10, and the manufacturing of the composite segment 100 becomes easier.

[0082] The connecting reinforcing bars 50a and the inner reinforcing bars 40 and protruding plates 30a are not joined by welding or the like. When concrete 80 is poured into the steel shell 10 and the concrete 80 hardens, the connecting reinforcing bars 50a and the inner reinforcing bars 40 and protruding plates 30a are joined together. However, the connecting reinforcing bars 50a and the inner reinforcing bars 40 and protruding plates 30a may be joined by welding or the like before the concrete 80 is poured.

[0083] The connecting reinforcing bar 50a shown in Figure 14 is an example formed in a U-shape, but the shape of the connecting reinforcing bar 50a is not limited as long as it connects the inner reinforcing bar 40 and the protruding plate 30a. For example, the connecting reinforcing bar 50a may be formed in a straight line in the middle and bent so that both ends face in opposite directions. Alternatively, the connecting reinforcing bar 50a may be formed in a straight line and both ends may be joined to the inner reinforcing bar 40 and the protruding plate 30a by welding or the like. Furthermore, the connecting reinforcing bar 50a may be in the shape of a rod or a plate.

[0084] Two connecting reinforcing bars 50a are arranged with an interval between them in the hole axis direction AD. The composite segment 100 has a connecting reinforcing bar 50a that engages with a protruding plate 30a provided on one of the pair of main girders 11, and another connecting reinforcing bar 50a that engages with a protruding plate 30a provided on the other main girder 11. However, the composite segment 100 may have only one of the connecting reinforcing bars 50a, for example, taking into consideration the size and shape of the composite segment 100. The number of connecting reinforcing bars 50a installed in the circumferential direction CD is determined, for example, taking into consideration the size and shape of the composite segment 100.

[0085] (Connected reinforcing bars 50b) Figure 15 is a cross-sectional view showing an example of the internal structure of a second modified example of the composite segment 100 according to Embodiment 2. The composite segment 100 may have connecting reinforcing bars 50b, as shown in Figure 15. The connecting reinforcing bars 50b are reinforcing bars that bridge the inner reinforcing bars 40 and the protruding plate 30a. The connecting reinforcing bars 50b are also reinforcing bars that connect the inner reinforcing bars 40 and the protruding plate 30a.

[0086] The connecting reinforcing bar 50b is a reinforcing bar that extends radially RD in the composite segment 100. The connecting reinforcing bar 50b is bent at both ends and is formed in a U-shape overall. The connecting reinforcing bar 50b is bent at both ends and is formed so that both ends extend in the hole axis direction AD. Because the connecting reinforcing bar 50b is formed in a U-shape, one end of the connecting reinforcing bar 50b is hooked onto the inner reinforcing bar 40 and the other end is inserted through the hole 31a of the protruding plate 30a, thereby engaging the connecting reinforcing bar 50b with the inner reinforcing bar 40 and the protruding plate 30a. Therefore, because the connecting reinforcing bar 50b is formed in a U-shape, it is easier to install the connecting reinforcing bar 50b inside the steel shell 10, and the manufacturing of the composite segment 100 is made easier. In the composite segment 100 of the second modified example, the straight-extending main body portion 50b1 of the connecting reinforcing bar 50b is inserted through the hole 31a of the protruding plate 30a.

[0087] The connecting reinforcing bars 50b, the inner reinforcing bars 40, and the protruding plates 30a are not joined by welding or the like. When concrete 80 is poured into the steel shell 10 and the concrete 80 hardens, the connecting reinforcing bars 50b, the inner reinforcing bars 40, and the protruding plates 30a are joined. However, the connecting reinforcing bars 50b, the inner reinforcing bars 40, and the protruding plates 30a may be joined by welding or the like before the concrete 80 is poured.

[0088] The connecting reinforcing bar 50b shown in Figure 15 is an example formed in a U-shape, but the shape of the connecting reinforcing bar 50b is not limited as long as it connects the inner reinforcing bar 40 and the protruding plate 30a. For example, the connecting reinforcing bar 50b may be formed in a straight line in the middle and bent so that both ends face in opposite directions. Alternatively, the connecting reinforcing bar 50b may be formed in a straight line and both ends may be joined to the inner reinforcing bar 40 and the protruding plate 30a by welding or the like. Furthermore, the connecting reinforcing bar 50b may be in the shape of a rod or a plate.

[0089] Two connecting reinforcing bars 50b are arranged with an interval between them in the hole axis direction AD. The composite segment 100 has a connecting reinforcing bar 50b that engages with a protruding plate 30a provided on one of the pair of main girders 11, and another connecting reinforcing bar 50b that engages with a protruding plate 30a provided on the other main girder 11. However, the composite segment 100 may have only one of the connecting reinforcing bars 50b, for example, taking into consideration the size and shape of the composite segment 100. The number of connecting reinforcing bars 50b installed in the circumferential direction CD is determined by taking into consideration, for example, the size and shape of the composite segment 100.

[0090] Furthermore, the composite segment 100 of the first and second modified examples according to Embodiment 2 has outer reinforcement bars 41, but the outer reinforcement bars 41 may not be necessary depending on the strength required by the composite segment 100 or the size of the composite segment 100. Also, the composite segment 100 according to Embodiment 2 has both main reinforcement bars 42 and distribution reinforcement bars 44 as inner reinforcement bars 40. However, the composite segment 100 according to Embodiment 2 may have only one of the main reinforcement bars 42 or distribution reinforcement bars 44, depending on the strength required by the composite segment 100 or the size of the composite segment 100.

[0091] (Connected reinforcing bars 50c) Figure 16 is a cross-sectional view showing an example of the internal structure of a third modified example of the composite segment 100 according to Embodiment 2. As shown in Figure 16, the composite segment 100 may be provided with connecting reinforcing bars 50c that connect the inner reinforcing bars 40 and the outer reinforcing bars 41 by inserting them through the holes 31a of the protruding plate 30a within the concrete 80. The connecting reinforcing bars 50c are reinforcing bars that bridge the inner reinforcing bars 40 and the outer reinforcing bars 41 with the protruding plate 30a. Furthermore, the connecting reinforcing bars 50c are reinforcing bars that connect the inner reinforcing bars 40, the outer reinforcing bars 41, and the protruding plate 30a.

[0092] The connecting reinforcing bar 50c is a reinforcing bar that extends radially RD in the composite segment 100. The connecting reinforcing bar 50c is bent at both ends and is formed in a U-shape overall. The connecting reinforcing bar 50c is bent at both ends and is formed so that both ends extend in the hole axis direction AD. In the composite segment 100 of the third modified example, the straight-extending main body portion 50c1 of the connecting reinforcing bar 50c is inserted through the hole portion 31a of the protruding plate 30a.

[0093] In the manufacturing of the composite segment 100 of the third modified example, one end of the connecting reinforcing bar 50c is hooked onto the inner reinforcing bar 40, the main body portion 50c1 is inserted through the hole 31a of the protruding plate 30a, and the other end of the connecting reinforcing bar 50c is hooked onto the outer reinforcing bar 41. In the composite segment 100 of the third modified example, the connecting reinforcing bar 50c engages with the inner reinforcing bar 40, the outer reinforcing bar 41, and the protruding plate 30a. In the composite segment 100 of the third modified example, the connecting reinforcing bar 50c is formed in a U-shape, making it easier to install the connecting reinforcing bar 50c inside the steel shell 10, and thus facilitating the manufacturing of the composite segment 100.

[0094] The connecting reinforcing bars 50c, the inner reinforcing bars 40, the outer reinforcing bars 41, and the protruding plates 30a are not joined by welding or the like. The connecting reinforcing bars 50c, the inner reinforcing bars 40, the outer reinforcing bars 41, and the protruding plates 30a are joined by pouring concrete 80 into the steel shell 10 and allowing the concrete 80 to harden. However, the connecting reinforcing bars 50c, the inner reinforcing bars 40, the outer reinforcing bars 41, and the protruding plates 30a may be joined by welding or the like before pouring the concrete 80.

[0095] The connecting reinforcing bar 50c shown in Figure 16 is an example formed in a U-shape, but the shape of the connecting reinforcing bar 50c is not limited as long as it connects the inner reinforcing bar 40, the outer reinforcing bar 41, and the protruding plate 30a. For example, the connecting reinforcing bar 50c may be formed in a straight line in the middle and bent so that both ends face in opposite directions. Alternatively, the connecting reinforcing bar 50c may be formed in a straight line and both ends may be joined to the inner reinforcing bar 40 and the outer reinforcing bar 41 by welding or the like. Furthermore, the connecting reinforcing bar 50c may be in the shape of a rod or a plate.

[0096] Two connecting reinforcing bars 50c are arranged with an interval between them in the hole axis direction AD. The composite segment 100 has a connecting reinforcing bar 50c that engages with a protruding plate 30a provided on one of the pair of main girders 11, and another connecting reinforcing bar 50c that engages with a protruding plate 30a provided on the other main girder 11. However, the composite segment 100 may have only one of the connecting reinforcing bars 50c, for example, taking into consideration the size and shape of the composite segment 100. The number of connecting reinforcing bars 50c installed in the circumferential direction CD is determined, for example, taking into consideration the size and shape of the composite segment 100.

[0097] [Effects of synthetic segment 100] The composite segment 100 extends in the circumferential direction CD within the steel shell 10 and has a protruding plate 30a with a plurality of holes 31 formed along the circumferential direction CD. The protruding plate 30a protrudes from the steel shell 10 into the concrete 80 and engages with the concrete 80. The composite segment 100 can achieve a high anchoring effect of the concrete 80 to the steel shell 10 by allowing the concrete 80 to fill the holes 31, thereby preventing displacement between the steel shell 10 and the concrete 80.

[0098] The composite segment 100 according to Embodiment 2 has connecting bars 50a, 50b, or 50c within the concrete 80 that connect the internal reinforcement 40 and the protruding plate 30. By having connecting bars 50a, 50b, or 50c, the composite segment 100 can improve its strength against the internal pressure applied to the earth retaining structure 200. In other words, the composite segment 100 according to Embodiment 2 can achieve both the prevention of shearing of the concrete 80 by having the protruding plate 30a and the improvement of strength against internal pressure by having connecting bars 50a etc. that utilize the protruding plate 30a.

[0099] Furthermore, the composite segment 100 is provided with connecting reinforcing bars 50c that connect the inner reinforcing bars 40 and the outer reinforcing bars 41 by inserting the holes 31a of the protruding plate 30a into the concrete 80. By having this configuration, the composite segment 100 can improve the strength of the concrete 80.

[0100] Furthermore, the connecting reinforcing bar 50a is bent at both ends to form a U-shape, with one end of the connecting reinforcing bar 50 hooked onto the inner reinforcing bar 40 and the other end inserted through the hole 31 of the protruding plate 30. As a result, the U-shape of the connecting reinforcing bar 50a makes it easier to install the connecting reinforcing bar 50a inside the steel shell 10 during the manufacturing of the composite segment 100, thereby facilitating the manufacturing of the composite segment 100.

[0101] Furthermore, the connecting reinforcing bars 50b and 50c are bent at both ends to form a U-shape, with one end of the connecting reinforcing bar 50 hooked onto the inner reinforcing bar 40 and the other end hooked onto the outer reinforcing bar 41. As a result, the U-shape of the connecting reinforcing bars 50b and 50c makes it easier to install them inside the steel shell 10 during the manufacture of the composite segment 100, thereby facilitating the manufacture of the composite segment 100.

[0102] Furthermore, the protruding plate 30a is provided on the main girder 11. By providing the protruding plate 30a on the main girder 11, the rigidity of the main girder 11 is increased, and the compressive strength of the composite segment 100 can be strengthened. In addition, by providing the protruding plate 30a on the main girder 11, it becomes easier to install the U-shaped connecting reinforcing bars 50a, etc., on the protruding plate 30a, making the manufacturing of the composite segment 100 easier compared to a composite segment that does not have this configuration.

[0103] Furthermore, since the earth retaining structure 200 has composite segments 100, the effects of the composite segments 100 described above can be realized.

[0104] The configurations shown in the above embodiments are merely examples, and can be combined with other known technologies. It is also possible to omit or modify parts of the configuration without departing from the gist of the invention. [Explanation of Symbols]

[0105] 10 Steel shell, 11 Main girder, 12 Joint plate, 13 Bolt hole, 14 Boss, 15 Bolt hole, 16 Skin plate, 20 Shape-retaining material, 30 Protruding plate, 30a Protruding plate, 31 Hole section, 31a Hole section, 40 Inner reinforcement, 41 Outer reinforcement, 42 Main reinforcement, 43 Main reinforcement, 44 Distribution reinforcement, 45 Distribution reinforcement, 50 Connecting reinforcement, 50a Connecting reinforcement, 50b Connecting reinforcement, 50b1 Main body section, 50c Connecting reinforcement, 50c1 Main body section, 60 Gap, 80 Concrete, 81 Bolt box, 82 Bolt box, 100 Composite segment, 150 Segment ring, 200 Earth retaining structure, AD Hole axis direction, CD Circumferential direction, RD Radial direction.

Claims

1. A composite segment that is connected in multiple ways in the circumferential and axial directions of the earth retaining structure to construct the earth retaining structure, Steel shell and, The steel shell is filled with concrete, The aforementioned steel shell is A pair of main girders 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 in the circumferential direction of the main girder, Within the steel shell, a protruding plate extends from the main girder into the concrete, extends circumferentially along the main girder, has multiple through-holes formed along the circumferential direction, and the concrete enters into the multiple holes and engages with the concrete; It has, Within the aforementioned concrete, The main reinforcement extending in the circumferential direction, The aforementioned axially extending force distribution reinforcement is provided, An inner reinforcing bar arranged on the inner circumference, which is composed of the main reinforcement or the main reinforcement and the distribution reinforcement, Outer reinforcement bars are arranged on the outer periphery and consist of the main reinforcement bars or the main reinforcement bars and the distribution reinforcement bars, A connecting reinforcing bar that connects the inner reinforcing bar and the protruding plate, It has, The aforementioned connecting reinforcement is Both ends are bent to form a U-shape, with one end hooked onto the inner reinforcing bar and the other end inserted into some of the multiple holes. Synthetic segment.

2. The aforementioned steel shell is It has a shape-retaining member joined between the pair of main girders. The synthetic segment according to claim 1.

3. The aforementioned protruding plate is The tip in the protruding direction is joined to the shape-retaining material. The synthetic segment according to claim 2.

4. The connecting reinforcing bar is The inner reinforcing bar and the outer reinforcing bar are connected by inserting them through the holes in the protruding plate. A synthetic segment according to any one of claims 1 to 3.

5. The aforementioned connecting reinforcement is One end is hooked onto the inner reinforcing bar, and the other end is hooked onto the outer reinforcing bar. A synthetic segment according to any one of claims 1 to 3.

6. A retaining structure formed by combining a plurality of composite segments according to any one of claims 1 to 5 in the circumferential and axial directions.

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