Segment and segment manufacturing method

Abstract

To provide a segment capable of suppressing falling of concrete of the segment in a tunnel during a large scale earthquake at low cost by efficiently reinforcing a portion of a tunnel cross section, at which generated sectional force becomes strong, and also to provide a segment manufacturing method.SOLUTION: A segment 10 is provided on a tunnel 1 having a circular cross section so that concrete is exposed to a tunnel inner surface. A reinforcement member 11 is provided so as to include at least a portion on the tunnel inner surface side in at least either one of first reinforcement ranges D1 of 30° to 60° and -30° to -60° from a tunnel top portion P0 in a tunnel circumferential direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a segment and a method for producing the segment. [Background technology]

[0002] Conventionally, in shield tunnels with an approximately circular cross-section in which concrete is exposed on the inner surface of the tunnel, when a large earthquake occurs, cracks or damage occur in the concrete on the inner surface of the segments, and there is a risk that the concrete will spall off (see, for example, Patent Document 1).

[0003] Specifically, when an earthquake occurs, a shear force acts on the tunnel cross section in the cross-sectional direction, causing it to deform into an oblique ellipse. At this time, a large negative bending moment is generated by the seismic force in addition to the axial compression force at the diagonally upward and downward diagonal parts of the tunnel. The negative bending moment is compression (tension) on the inner side of the tunnel and tension (compression) on the outer side of the tunnel. In shield tunnels constructed with segments such as RC segments and five-sided steel shell type composite segments, the concrete is exposed on the inner side of the tunnel, so as the seismic load increases, the negative bending moment and the axial compression force in the circumferential direction of the tunnel become dominant in this area, and the compression of the concrete on the inner side of the tunnel becomes dominant. On the other hand, the diagonally upward and downward diagonal parts of the tunnel are subjected to axial compression force and positive bending moment due to seismic force, and although cracks occur in the concrete in these parts, the part where the negative bending moment acts is the most severe condition. In addition, since the seismic load is a repeated load, positive and negative bending are repeatedly applied to the diagonally upward and downward diagonal parts of the tunnel on the left and right. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 7-23098 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned conventional segments having concrete exposed on their inner surfaces have the following problems. As mentioned above, when a large seismic force acts on a shield tunnel, axial force and bending moment act in the direction transverse to the tunnel. In the case of RC segments and composite segments, concrete is exposed on the inner surface of the tunnel, but since concrete has poor deformation performance, it may be destroyed by seismic force (compressive failure (hereinafter referred to as crushing) or splitting failure) and fall into the tunnel, which is an event that must be avoided. As a result of research, the inventors found that concrete is particularly susceptible to destruction by crushing and splitting cracks at diagonal upward and downward angles on the left and right sides of the tunnel (near ±45° and ±135° from the top of the tunnel cross section) due to repeated loads caused by earthquakes, and that there is a particular risk of concrete falling into the tunnel on a large scale at an upward diagonal angle.

[0006] In addition, while it is possible to improve earthquake resistance by using segments made of high-strength materials, this has the problem of being expensive, and it is not possible to reliably prevent the concrete in the segments from falling, so there is room for improvement in this regard.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a segment and a manufacturing method for the segment that can efficiently reinforce areas of the tunnel cross section where the cross-sectional stress generated is severe, thereby preventing large-scale concrete from falling into the tunnel during a large-scale earthquake at low cost. [Means for solving the problem]

[0008] (1) A first aspect of the segment of the present invention is a segment installed in a tunnel with a circular cross-section, with concrete exposed on the inner surface of the tunnel, characterized in that a reinforcing member is provided in a first reinforcement range of at least one of 30° to 60° and -30° to -60° from the tunnel ceiling in the circumferential direction of the tunnel, including at least a part of the tunnel inner surface side.

[0009] In the present invention, when a large-scale earthquake acts on a shield tunnel, axial force and bending moment act in the circumferential direction of the tunnel across the tunnel, and reinforcing members such as steel plates, FRP plates, carbon fiber sheets, resin mortar, and fiber-reinforced concrete are provided to reinforce a first reinforcement range including a part of the inner side of the segment, which is a first reinforcement range including the diagonally upper part of the tunnel where the axial force and bending moment are dominant. Therefore, since the reinforcing members improve the strength and the deformation performance, it is possible to prevent the concrete in the first reinforcement range from collapsing or splitting. In addition, even if the concrete does collapse or splitting, it is supported by the reinforcing members, so that it is possible to prevent the concrete of the segment in the first reinforcement range from falling on a large scale into the interior of the tunnel.

[0010] Furthermore, in the present invention, a reinforcing member is provided on at least a portion of the inner surface side of the tunnel in the first reinforcement range, which is at least one of 30° to 60° and -30° to -60° from the tunnel top in the circumferential direction of the tunnel, and since reinforcement is not provided around the entire circumference of the tunnel in the circumferential direction, material costs can be reduced. Furthermore, in the present invention, since reinforcing members are provided for each individual segment, it is possible to manufacture segments equipped with reinforcing members at the time of segment manufacture, allowing for more efficient and effective reinforcement than when the tunnel is reinforced after the segments are assembled inside the tunnel. In this way, the present invention makes it possible to efficiently reinforce the structure and prevent the concrete in the segments from falling, thereby reducing costs and achieving earthquake-resistance reinforcement.

[0011] (2) A second aspect of the present invention may be characterized in that, in the segment of the first aspect, the tunnel segments are staggered, and a first segment joint connecting the segment ends is arranged in the first reinforcement range in the tunnel circumferential direction, and the reinforcing member is provided at least in a range that includes the first segment joint in the tunnel circumferential direction and in a range that is connected to the segment body of a ring adjacent in the tunnel axial direction to the range that includes the first segment joint.

[0012] In this case, the area including the first segment joint and the area of ​​the adjacent ring can be reliably reinforced by the reinforcing member.

[0013] (3) A third aspect of the present invention may be characterized in that, in the segment of the first aspect, the tunnel segments are staggered, a first segment joint connecting the segment ends in the tunnel circumferential direction is arranged in the first reinforcement range, and the reinforcing member is provided on only the segment body of the ring adjacent in the tunnel axial direction to the first segment joint arranged in the first reinforcement range.

[0014] In this case, by staggering the segments, the bending moment that the segment joint should bear is reduced, and the bending moment of the segment body of the adjacent ring is increased (this is called the splice effect). In other words, the bending rigidity of the first segment joint (as well as general segment joints) is smaller than that of the segment body, so force tends to flow to the side with the larger bending rigidity. Therefore, crushing or splitting of the concrete in one ring adjacent to the segment joint surface of the other ring is likely to occur. Therefore, by providing reinforcing members only in the reinforcement area of ​​the other ring adjacent to the segment joint surface of one ring, reinforcement can be achieved efficiently while reducing the number of reinforcing members. In other words, reinforcing members can be arranged efficiently and effectively.

[0015] (4) A fourth aspect of the segment of the present invention is a segment installed in a tunnel with a circular cross-section, with the concrete exposed on the inner surface of the tunnel, characterized in that a reinforcing member is provided in at least one of a second reinforcement range of 120° to 150° and -120° to -150° from the tunnel ceiling in the circumferential direction of the tunnel, including at least a part of the tunnel inner surface side.

[0016] In the present invention, when a large-scale earthquake acts on a shield tunnel, axial force and bending moment act in the circumferential direction of the tunnel to cross the tunnel, and reinforcing members such as steel plates, FRP plates, carbon fiber sheets, resin mortar, and fiber-reinforced concrete are provided to reinforce a range including a part of the inner side of the segment in the second reinforcement range including the diagonally downward part of the tunnel where the axial force and bending moment are dominant. Therefore, since the reinforcing members improve the strength and the deformation performance, it is possible to prevent the concrete in the second reinforcement range from collapsing or splitting. In addition, even if the concrete does collapse or splitting, it is supported by the reinforcing members, so that it is possible to prevent the concrete of the segment in the second reinforcement range from falling on a large scale into the interior of the tunnel.

[0017] (5) A fifth aspect of the present invention may be characterized in that, in the segment of the fourth aspect, the tunnel segments are staggered, a second segment joint connecting the segment ends in the tunnel circumferential direction is arranged in the second reinforcement range, and the reinforcing member is provided in at least a range including the second segment joint in the tunnel circumferential direction and a range connected to the segment body of a ring adjacent in the tunnel axial direction to the range including the second segment joint.

[0018] In this case, the area including the second segment joint and the area of ​​the adjacent ring can be reliably reinforced by the reinforcing member.

[0019] (6) A sixth aspect of the present invention may be characterized in that, in the segment of the fourth aspect, the tunnel segments are staggered, second segment joints connecting the segment ends in the tunnel circumferential direction are arranged in the second reinforcement range, and the reinforcing member is provided on the segment body only of the ring adjacent in the tunnel axial direction to the second segment joint arranged in the second reinforcement range.

[0020] In this case, by staggering the segments, the concrete of one ring adjacent to the segment joint surface of the other ring is likely to be crushed or split due to the splice effect, as in the third embodiment. Therefore, by providing reinforcing members only in the reinforcing area of ​​the other ring adjacent to the segment joint surface of one ring, the reinforcing members can be arranged efficiently and effectively.

[0021] (7) A seventh aspect of the present invention may be characterized in that, in any one of the segments of the first to sixth aspects, the reinforcement length of the reinforcing member extending in the circumferential direction of the tunnel is equal to or greater than the segment girder height and is in the range of an angle of 30° or less in the circumferential direction of the tunnel.

[0022] In this case, by setting the reinforcement length to such dimensions, the tunnel can be reinforced efficiently and effectively. In other words, since the same cross-sectional forces are generated within a range of at most 30° in the tunnel circumferential direction X1, centered on ±45° from the tunnel zenith, it is preferable to reinforce this range. For example, when reinforcing the area around +45° from the zenith of the tunnel cross section, it is preferable to reinforce the range from +30° to +60°. On the other hand, it is preferable that the minimum reinforcement range in the circumferential direction of the tunnel be the same as the girder height of the segment. This is because the range of collapse when a negative bending moment that compresses the empty side of the tunnel is applied is minimized and is approximately equal to the segment girder height, and by doing so, collapse of the concrete on the empty side of the tunnel can be efficiently prevented.

[0023] (8) An eighth aspect of the present invention may be characterized in that, in the segment of the seventh aspect, the reinforcing length of the reinforcing member is not less than two times and not more than four times the segment girder height.

[0024] In this case, by setting the reinforcement length to such dimensions, the tunnel can be reinforced more efficiently and effectively. In other words, because alternating positive and negative loads act on the tunnel during an earthquake, there is a risk that positive and negative bending moments will act repeatedly on the tunnel at angles of ±45° and ±135° from the zenith of the cross section, along with axial force (axial compression force). Damage is likely to accumulate on the inner side of the tunnel due to the repeated stresses, and the damage range of the concrete in the circumferential direction of the tunnel will also increase, and this range will generally be more than two times and less than four times the girder height of the segment. Therefore, it is effective and economical to reinforce the range of the tunnel circumferential direction X1 within a range of more than two times and less than four times the girder height of the segment.

[0025] (9) A ninth aspect of the present invention may be characterized in that, in the segment of any one of the first to sixth aspects, the inner circumferential surface of the reinforcing member is flush with the inner surface of the tunnel.

[0026] In this case, the inner peripheral surface of the covering reinforcement member does not protrude from the inner surface of the tunnel of the segment, so that the covering reinforcement member can be prevented from interfering with other components or being damaged when the segment is transported.

[0027] (10) A tenth aspect of the method for manufacturing a segment according to the present invention is a method for manufacturing a segment that is installed in a tunnel with a circular cross-section, and in which a reinforcing member is provided in a first reinforcing range that is at least one of 30° to 60° and -30° to -60° from the tunnel ceiling in the tunnel circumferential direction, including at least a part of the tunnel inner surface side of the segment, and is characterized by having a step of pouring concrete inside a circular plate-shaped frame body so as to expose a part of the concrete on the inner surface, and a step of reinforcing the first reinforcing range by providing a reinforcing member, including at least a part of the tunnel inner surface side of the segment.

[0028] (11) An eleventh aspect of the method for manufacturing a segment according to the present invention is a method for manufacturing a segment that is installed in a tunnel with a circular cross-section and in which a reinforcing member is provided in a second reinforcing range that is at least one of 120° to 150° and -120° to -150° from the tunnel ceiling in the tunnel circumferential direction, including at least a part of the tunnel inner surface side of the segment, characterized in that it includes the steps of pouring concrete inside a circular plate-shaped frame body so as to expose a part of the concrete on the inner surface, and reinforcing the second reinforcing range by providing a reinforcing member, including at least a part of the tunnel inner surface side of the segment.

[0029] In the present invention, when a large-scale earthquake acts on a shield tunnel, axial force and bending moment act in the tunnel circumferential direction when crossing the tunnel, and a segment can be manufactured in which reinforcing members such as steel plates, FRP plates, carbon fiber sheets, resin mortar, and fiber-reinforced concrete are provided to reinforce a range including a part of the inner side of the segment, which is the first reinforcement range (second reinforcement range) including a 45° diagonal of the tunnel where the axial force and bending moment are dominant. Therefore, since the reinforcing members improve the strength and improve the deformation performance, it is possible to prevent crushing and splitting failure of the concrete in the first reinforcement range (second reinforcement range). In addition, even if crushing or splitting failure occurs in the concrete, it is possible to prevent the concrete of the segment in the first reinforcement range (second reinforcement range) from falling on a large scale into the interior of the tunnel because it is supported by the reinforcing members. Effect of the Invention

[0030] According to the segments and segment manufacturing method of the present invention, by efficiently reinforcing the areas of the tunnel cross section where the cross-sectional stresses generated are severe, it is possible to prevent large-scale concrete from falling into the tunnel during a large-scale earthquake at low cost. [Brief description of the drawings]

[0031] [Figure 1] FIG. 1 is a perspective view showing a tunnel according to a first embodiment of the present invention. [Diagram 2] A cross-sectional view showing the reinforced area of ​​the tunnel. [Diagram 3] FIG. 2 is an exploded view of the upper half of the tunnel, showing the inner surface of the segments. [Figure 4] FIG. 13 is a partial perspective view of a segment provided with a reinforcing member. [Diagram 5] FIG. 13 is a partial perspective view of a segment provided with a reinforcing member. [Figure 6] FIG. 11 is an exploded view of the upper half of the tunnel according to the second embodiment, showing the inner surface of the segments. [Figure 7] FIG. 7 is a partial perspective view of a segment provided with the reinforcing member shown in FIG. 6. [Figure 8] FIG. 7 is a partial perspective view of a segment provided with the reinforcing member shown in FIG. 6. [Figure 9] FIG. 11 is an exploded view of the upper half of the tunnel according to the third embodiment, showing the inner surface of the segments. [Figure 10] 10 is a cross-sectional view taken along line XX shown in FIG. 9. [Figure 11] FIG. 11 is a partial perspective view of a composite segment according to a first modified example. [Figure 12] FIG. 11 is a partial perspective view of a composite segment according to a second modified example. [Figure 13] FIG. 11 is a partial perspective view of a composite segment according to a third modified example. [Figure 14] FIG. 11 is a partial perspective view of a composite segment according to a fourth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A segment and a method for manufacturing a segment according to an embodiment of

[0033] (First embodiment) 1 and 2, a segment 10 according to the first embodiment is installed in a tunnel 1 with a circular cross section, and is a partially reinforced segment in which the concrete is exposed to the inner surface of the tunnel. In this embodiment, an RC segment (reinforced concrete segment) will be described as an example.

[0034] For example, in a shield tunneling method, a plurality of segments 10 are connected in the tunnel circumferential direction X1 and the tunnel axial direction X2 along the inner wall of a borehole of a tunnel 1 excavated in the natural ground to form a cylindrical wall body. The segments 10 are formed in an arc-shaped plate shape having a radius of curvature approximately equal to the radius of curvature of the inner surface of the borehole of the tunnel 1. In other words, the segments 10 form a quadrangular frame shape curved on an arc on the tunnel outer circumferential surface side.

[0035] The segments 10 are assembled in a staggered arrangement in which the joining positions of adjacent rings in the tunnel circumferential direction X1 in the tunnel axial direction X2 are shifted in the tunnel circumferential direction X1 (this is called a staggered set). Hereinafter, one of the adjacent rings will be referred to as the first ring R1, and the other as the second ring R2. The first ring R1 and the second ring R2 are arranged alternately in the tunnel axial direction X2.

[0036] Inside the concrete of the segment 10, a plurality of main reinforcing bars are arranged on the inner space side and the natural ground side, extending in an arc shape in the tunnel circumferential direction X1. The segment 10 has an arc-shaped tunnel inner surface 10a and a tunnel outer surface 10b, a pair of arc-shaped ring joint surfaces 10d arranged opposite each other at a predetermined interval in the tunnel axial direction X2, and a pair of segment joint surfaces 10c arranged opposite each other at a predetermined interval in the tunnel circumferential direction X1. The tunnel inner surface 10a and the tunnel outer surface 10b are located on the inner and outer circumferential sides of the pair of ring joint surfaces 10d and the pair of segment joint surfaces 10c, respectively. The ring joint surfaces 10d and the segment joint surfaces 10c are segment end surfaces that include joints such as bolts (not shown).

[0037] The size of the segment 10 can be appropriately changed depending on the ease of transport, assembly, etc. The arcuate curvature of the segment 10 is appropriately determined depending on the cross section of the tunnel to be excavated. Also, for example, in Figures 1 and 2, a so-called K segment (symbol 10K in the figures) is used in which the installation angle of the segment joint surface 10c and the length dimension in the tunnel circumferential direction X1 are appropriately changed so that the segment 10 can be fitted last when assembling the segment 10.

[0038] The segments 10 in the tunnel circumferential direction X1 and the tunnel axial direction X2 are fixed to each other by fastening means (not shown) such as bolts.

[0039] As shown in Fig. 3, the segment 10 is provided with a reinforcing member 11 that reinforces at least a part of the tunnel inner surface 10a. The reinforcing member 11 is arranged in at least a part of the tunnel inner surface side of a first reinforcement range D1 at least one of 30° to 60° and -30° to -60° from the tunnel vertex P0 in the tunnel circumferential direction X1 (the entire region of the first reinforcement range D1 shown in Fig. 3 in this embodiment) and at least a part of the tunnel inner surface side of a second reinforcement range D2 at least one of 120° to 150° and -120° to -150° from the tunnel vertex P0 in the tunnel circumferential direction X1 (the entire region of the second reinforcement range D2 in this embodiment). Therefore, the reinforcing member 11 of each segment 10 has a different reinforcing range depending on the position in the tunnel circumferential direction X1 of one ring.

[0040] A first reinforcing member 11 is provided in the first reinforcement range D1 of the segment 10, including at least a part of the tunnel inner surface side. The first reinforcing member 11 is provided at least in a range including the first segment joint (a joint provided on the segment joint surface 10c) in the tunnel circumferential direction X1, and in a range connected to the segment body of the ring adjacent in the tunnel axial direction X2 to the range including the first segment joint.

[0041] In the second reinforcement area D2 of the segment 10, a second reinforcement member 12 is provided at least in a part of the tunnel inner surface side. The second reinforcement member 12 is provided at least in an area including the second segment joint (a joint provided on the segment joint surface 10c) in the tunnel circumferential direction X1, and in an area connected to the segment body of the ring adjacent in the tunnel circumferential direction to the area including the second segment joint. Note that the above-mentioned first segment joint and second segment joint generally have the same configuration.

[0042] The reinforcing members 11 and 12 are curved members that fit the tunnel inner surface 10a of the segment 10. Examples of the reinforcing member 11 include a steel plate, an FRP plate, a carbon fiber sheet, a mesh, a resin mortar, and a fiber-reinforced concrete. The reinforcing member 11 is fixed to the segment body by a fastening means such as adhesion, welding, bolts / nuts, and hooks. In this embodiment, the segment body is filled with concrete C or steel materials such as reinforcing bars and steel plates. The reinforcing members 11 are preferably fixed to steel materials such as reinforcing bars in the segment body so as not to fall together with the concrete C.

[0043] If the compressive strain generated in a tunnel by bending moment and compressive axial force during an earthquake exceeds the limit value of the concrete material, collapse will occur, and the maximum compressive strain will occur on the tunnel inner surface 10a or the tunnel outer surface 10b, causing the concrete to collapse. If the tunnel inner surface 10a collapses, the concrete will fall into the tunnel. Therefore, in order to prevent the concrete from falling, it is effective to at least reinforce the concrete on the tunnel inner surface side.

[0044] When a carbon fiber sheet is used as the reinforcing member 11, for example, as shown in Fig. 4, the carbon fiber sheet may be placed on the tunnel inner surface 10a of the segment 10 and fixed by adhering it to the concrete C. In this case, the thickness of the reinforcing member 11 can be set to be extremely thin. This makes it possible to reinforce the tunnel without invading the space inside the tunnel, without impeding the flow of compressive strain and compressive stress generated on the tunnel inner surface 10a, and without causing local stress concentration, and thus makes it possible to efficiently reinforce the tunnel while preventing localized collapse of the concrete.

[0045] Furthermore, when a resin mortar board or fiber reinforced concrete is used as the reinforcing member 11, it can be installed by placing a resin mortar board or fiber reinforced concrete on the tunnel inner surface 10a side of the segment 10, and then filling it with concrete C of the segment body, as shown in Figure 5, for example. Alternatively, a space is provided on the tunnel outer surface 10b side of the segment 10 by using a formwork or the like, and concrete is poured into the space. After the concrete hardens, resin mortar or fiber-reinforced concrete can be poured into the space, or a separately manufactured resin mortar plate or fiber-reinforced concrete plate can be fixed by gluing or the like. In this case, the reinforcing member 11 can be finished flush with the tunnel inner surface 10a. This not only allows the tunnel inner space to be effectively utilized without invading it, but also allows the flow of compressive strain and compressive stress generated on the tunnel inner surface 10a to be smoothly transmitted to the reinforcing member 11, making it possible to prevent stress concentration around the reinforcing member 11 and localized concrete collapse, and therefore more reliably prevents the concrete C from falling.

[0046] If the reinforcing member 11 is a steel plate or an FRP plate, it can be joined by a joining means such as a bolt (not shown) to a nut (not shown) embedded in the inner surface of the concrete. Alternatively, the steel plate may be arranged on the tunnel inner surface 10a of the segment 10 by being fixed to the reinforcing bars in the concrete by welding, hooks, or the like. In this case, the inner peripheral surface of the reinforcing member 11 protrudes slightly from the tunnel inner surface 10a of the segment 10. In this case, it becomes possible to more firmly connect the reinforcing member 11 to the segment body, and the falling of the concrete C can be more reliably suppressed.

[0047] 2 and 3, the reinforcement length L of the reinforcing members 11, 12 extending in the tunnel circumferential direction X1 is equal to or greater than the segment girder height H and is in the range of a reinforcement angle θ in the tunnel circumferential direction X1 of 30° or less. More preferably, the reinforcement length L of the reinforcing members 11, 12 is equal to or greater than two times and equal to or less than four times the segment girder height H.

[0048] By arranging them in this way, the inventors have found through research that the range in which the cross-sectional force generated in the tunnel due to an earthquake is the largest, i.e. the range in which the maximum cross-sectional force occurs, and in particular the range in which the cross-sectional force as a result of the axial force (axial compression force) and bending moment (negative bending moment in which the interior side of the tunnel is compressed) is the largest, is approximately ±45° and ±135° inclined from the tunnel zenith P0. Therefore, by reinforcing these areas, it is possible to prevent the concrete from collapsing or splitting, or, in the unlikely event that the concrete does collapse or splitting, the reinforcing members will increase its strength and improve its deformation performance, preventing the concrete in the segments in this range from falling on a large scale into the interior side of the tunnel.

[0049] In other words, since the same cross-sectional forces are generated within a range of at most 30° in the tunnel circumferential direction X1, centered on ±45° from the tunnel zenith P0, it is preferable to reinforce this range. For example, when reinforcing the area around +45° from the zenith of the tunnel cross section, it is preferable to reinforce the range from +30° to +60°.

[0050] On the other hand, it is preferable that the minimum reinforcement range in the circumferential direction of the tunnel be the same as the girder height of the segment. This is because the range of collapse when a negative bending moment that compresses the empty side of the tunnel is applied is minimized and is approximately equal to the segment girder height, and by doing so, collapse of the concrete on the empty side of the tunnel can be efficiently prevented.

[0051] Furthermore, because alternating positive and negative loads act on the tunnel during an earthquake, there is a risk that positive and negative bending moments will act repeatedly on the tunnel at angles of ±45° and ±135° from the apex P0 of the cross section, along with axial force (axial compression force). Damage is likely to accumulate on the inner side of the tunnel due to the repeated stresses, and the damage range of the concrete in the tunnel circumferential direction X1 will also increase, and this range will generally be more than two times and less than four times the girder height of the segment. Therefore, it is effective and economical to reinforce the range of the tunnel circumferential direction X1 within the range of more than two times and less than four times the girder height of the segment.

[0052] Next, a method for manufacturing the segment 10 according to the above-mentioned first embodiment will be described. First, a form for the arc-shaped plate-shaped frame is set up, and then reinforcing bars, joints, etc. are placed in their designated positions within the form. Next, reinforcing members 11, 12 are arranged so as to cover at least a portion of the reinforced area of ​​the segment on the tunnel inner surface side. That is, reinforcing members 11, 12 are arranged to cover the opening faces of the formwork so as to form the tunnel inner surface 10a of the segment 10 in an arc shape. At this time, reinforcing members 11, 12 only need to be arranged so as to cover at least a portion of the reinforced area of ​​the segment on the tunnel inner surface side, and their thickness is optional. For example, the entire segment girder height direction, including a portion of the segment on the tunnel inner surface side, may be reinforced with resin mortar or the like.

[0053] Thereafter, concrete C is poured inside the formwork so that a part of the concrete C is exposed on the tunnel inner surface 10a of the segment. Then, the concrete C hardens and attains a predetermined strength, whereby the segment 10 is manufactured. This makes it possible to manufacture the segment 10 that is provided in the tunnel 1 with a circular cross section and is arranged to include at least a part of the first reinforcement range D1 at least one of 30° to 60° and -30° to -60° from the tunnel vertex P0 in the tunnel circumferential direction X1.

[0054] According to the segment 10 described above, when a large-scale earthquake acts on the shield tunnel, axial force and bending moment act in the tunnel circumferential direction X1, and the first reinforcement range D1 (at least one of 30° to 60° and -30° to -60° from the tunnel top P0 in the tunnel circumferential direction X1) including the diagonally upward part of the tunnel where the axial compressive force and bending moment are dominant is provided with reinforcing members 11 such as steel plates, FRP plates, carbon fiber sheets, resin mortar, and fiber-reinforced concrete in a range including a part of the tunnel inner surface 10a side of the segment 10. Therefore, since the reinforcing members 11 improve the strength and enhance the deformation performance, it is possible to suppress the crushing and splitting failure of the concrete in the first reinforcement range D1. In addition, even if crushing or splitting failure occurs in the concrete C (see Figs. 4 and 5), it is possible to suppress the concrete C of the segment in the first reinforcement range D1 from falling into the tunnel interior space on a large scale because it is supported by the reinforcing members.

[0055] Moreover, in this embodiment, the reinforcing member 12 may be provided in a part of the tunnel inner surface 10a side of the segment 10, which is the second reinforcement range D2 (at least one of 120° to 150° and -120° to -150° from the tunnel apex P0 in the tunnel circumferential direction X1) including the diagonally downward direction of the tunnel 1 when a large-scale earthquake acts. Therefore, since the reinforcing member 11 improves the strength and enhances the deformation performance, it is possible to suppress the crushing and splitting failure of the concrete in the second reinforcement range D2 in addition to the first reinforcement range D1. Furthermore, even if crushing or splitting failure occurs in the concrete C (see Figs. 4 and 5), it is possible to suppress the concrete C of the segment in the second reinforcement range D2 from falling into the tunnel interior on a large scale because it is supported by the reinforcing member 12.

[0056] Furthermore, in this embodiment, the reinforcing member 11 is provided on at least a part of the tunnel inner surface side of the first reinforcement range D1, which is at least one of 30° to 60° and -30° to -60° from the tunnel vertex P0 in the tunnel circumferential direction X1, and since reinforcement is not provided over the entire circumference of the tunnel in the tunnel circumferential direction X1, material costs can be reduced.

[0057] Furthermore, in this embodiment, since the reinforcing member 11 is provided for each segment alone, the segment 10 equipped with the reinforcing member 11 can be manufactured at the time of segment manufacturing, and reinforcement can be achieved more efficiently and effectively than in the case where the reinforced tunnel is reinforced after the segments 10 are assembled inside the tunnel 1. In this manner, in this embodiment, by preventing the concrete C of the segment 10 from falling, earthquake resistance reinforcement can be achieved while keeping costs down.

[0058] In this embodiment, the reinforcing length L of the reinforcing member 1 extending in the tunnel circumferential direction X1 is equal to or greater than the segment girder height H and is in the range of an angle of 30° or less in the tunnel circumferential direction X1, and more preferably is equal to or greater than two times and equal to or less than four times the segment girder height H. In this case, by setting the reinforcing length L to such a dimension, the reinforcing member 11 can be arranged efficiently and effectively.

[0059] In this embodiment, the inner peripheral surface 11a of the reinforcing member 11 may be flush with the tunnel inner surface 10a of the segment 10. In this case, the inner peripheral surface 11a of the reinforcing member 11 does not protrude from the tunnel inner surface 10a of the segment 10, so that the reinforcing member 11 can be prevented from interfering with or being damaged during transportation of the segment.

[0060] As described above, the segment and segment manufacturing method according to this embodiment can efficiently and effectively prevent the concrete of the segment 10 from falling into the tunnel 1 during a large-scale earthquake. In other words, it is only necessary to reinforce the tunnel inner surface side in at least one of the ranges of 30° to 60° and -30° to -60° in the circumferential direction of the tunnel from the tunnel zenith P0, which is the cross section where the compressive stress due to the bending moment and axial force generated in the tunnel is the largest, or in at least one of the ranges of 120° to 150° and -120° to -150°. Furthermore, since the tunnel inner surface 10a of the segment 10 is reinforced in advance at the factory, on-site reinforcement work is not required, and costs can be reduced.

[0061] Next, a segment and a method for manufacturing a segment according to another embodiment will be described with reference to the accompanying drawings. Note that the same or similar members and parts as those in the first embodiment described above will be designated by the same reference numerals, and the description will be omitted. Only configurations different from the first embodiment will be described.

[0062] Second embodiment As shown in FIG. 6, a reinforcing member 11A of a segment 10A according to the second embodiment shows an example applied when a segment joint surface 10c is disposed in the vicinity of ±45° from the tunnel vertex P0 in the tunnel circumferential direction X1.

[0063] The reinforcing member 11A is provided in the first reinforcement range D1 (at least one of a range of 30° to 60° and -30° to -60° from the tunnel zenith P0) according to the first embodiment described above and in the second reinforcement range D2 (at least one of a range of 120° to 150° and -120° to -150° from the tunnel zenith P0) not shown, in a first range d1 including the segment joint surface 10c of the upper ring R1, a second range d2 of the second ring R2 adjacent to the first range d1 in the tunnel axis direction X2, a third range d3 including the segment joint surface 10c of the second ring R2, and a fourth range d4 of the upper ring R1 adjacent to the third range d3 in the tunnel axis direction X2.

[0064] In the case where there are a plurality of segment joint surfaces 10c in each of the first reinforcement range D1 and the second reinforcement range D2 as in the second embodiment, the reinforcement length L is set to the same as that of the first embodiment at each segment joint surface 10c. That is, the reinforcement length L extending in the tunnel circumferential direction X1 of the reinforcing member 11 at each segment joint surface 10c is in the range of not less than the segment girder height H and not more than 30° at the reinforcement angle θ in the tunnel circumferential direction X1, and more preferably is not less than two times and not more than four times the segment girder height H.

[0065] Furthermore, when there are a plurality of segment joint surfaces 10c in the first reinforcement area D1 and / or the second reinforcement area D2 as in the second embodiment, a reinforcing member 11A is installed as shown in Figs.

[0066] Third embodiment 9, the reinforcing member 11C of the segment 10C according to the third embodiment shows an example applied when the segment joint surface 10c is arranged in the vicinity of ±45° from the tunnel zenith P0 in the tunnel circumferential direction X1. The reinforcing member 11C is provided only in the reinforcing range of the other ring adjacent in the tunnel axial direction X2 to the one ring where the segment joint surface 10c is provided, for example, in the case where the segment joint surface 10c is arranged in the first reinforcing range D1 (at least one of the ranges of 30° to 60° and -30° to -60° from the tunnel zenith P0) and the second reinforcing range D2 (at least one of the ranges of 120° to 150° and -120° to -150° from the tunnel zenith P0) not shown.

[0067] Specifically, the reinforcing member 11C is provided in a second range d2 of the second ring R2 adjacent to the segment joint surface 10c of the first ring R1 in the tunnel axis direction X2, and in a fourth range d4 of the first ring R1 adjacent to the segment joint surface 10c of the second ring R2 in the tunnel axis direction X2.

[0068] In the third embodiment, as shown in Fig. 10, the reinforcement length L is set to be the same as that of the first embodiment. That is, the reinforcement length L extending in the tunnel circumferential direction X1 of the reinforcing member 11C at each segment joint surface 10c is equal to or greater than the segment girder height H and is in the range of 30° or less at a reinforcement angle θ in the tunnel circumferential direction X1, and more preferably is equal to or greater than two times and equal to or less than four times the segment girder height H.

[0069] As in the third embodiment, the reinforcing members 11C provided in the second area d2 and the fourth area d4 are arranged efficiently and effectively in consideration of the splicing effect. The splice effect means that, as shown in Fig. 9, by staggering the segments 10C, the bending moment that the segment joint at the segment joint surface 10c should bear is reduced, and the bending moment burden of the segment body of the adjacent ring is increased. In other words, since the bending rigidity of the first segment joint is smaller than that of the segment body, the force (symbol F in Fig. 9) tends to flow to the side with the larger bending rigidity. Therefore, by providing the reinforcing member 11 on the segment body of the segment 10C in the reinforcement range of the other ring adjacent to the segment joint surface 10c of one ring, the reinforcing member 11C can be arranged efficiently and effectively. In this manner, in the third embodiment, the reinforcing member 11C is provided in the reinforcement areas (the second area d2 and the fourth area d4) of one ring adjacent to the segment joint surface 10c of the other ring.

[0070] Although the embodiments of the segment and the segment manufacturing method according to the present invention have been described above, the present invention is not limited to the above-mentioned embodiments and can be modified as appropriate without departing from the spirit of the present invention.

[0071] For example, in the above-mentioned embodiment, an RC segment (reinforced concrete segment) is applied as a segment to which the reinforcing member 11 is provided, but the present invention is not limited thereto, and may be applied to, for example, a composite segment 20 (20A to 20D) as shown in Fig. 11 to Fig. 14. In short, it is sufficient that the segment is provided in a tunnel with a circular cross section, and the tunnel inner surface including the first reinforcement range D1 (at least one of 30° to 60° and -30° to -60° from the tunnel zenith P0) or the second reinforcement range D2 (at least one of 120° to 150° and -120° to -150° from the tunnel zenith P0) is made of concrete, and that the segment includes at least a part of the tunnel inner surface side and has reinforced concrete.

[0072] Specifically, one example of the composite segment 20 includes an arc-shaped plate-shaped frame 21 formed of steel plates covering five faces of the segment other than the inner surface, and concrete 22 poured inside the arc-shaped plate-shaped frame 21. That is, the arc-shaped plate-shaped frame 21 includes a pair of main girders 23 arranged at both ends in the tunnel axial direction X2, a pair of joint plates 24 joined to both ends in the tunnel circumferential direction X1 of the pair of main girders 23, and a skin plate 25 curved into a cylindrical circumferential shape joined to the natural ground side of the tunnel of the main girders 23 and the joint plate 24. A rib material extending in the tunnel axial direction X2 and the tunnel circumferential direction X1 is generally provided on the inside of the arc-shaped plate-shaped frame 21. The composite segment 20 is provided with a reinforcing member 26 which includes at least a part of the concrete 22 on the inner surface. The reinforcing range, position, member, shape and other configuration and installation concept of the reinforcing member 26 are similar to those of the above-mentioned segments 10, 10A to 10C. For example, a steel plate can be placed on the tunnel inner surface side of the composite segment 20 and fixed to the steel shell by welding or the like.

[0073] The reinforcing member 26A of the composite segment 20A according to the first modified example shown in FIG.

[0074] A reinforcing member 26B of a composite segment 20B according to a second modified example shown in FIG. 12 is an example in which a steel plate is fixed to the arc-shaped plate-shaped frame 21 by fixing means such as welding or bolts (not shown) so that the steel plate is flush with the concrete 22.

[0075] A reinforcing member 26C of a composite segment 20C according to a third modified example shown in FIG. 13 is an example of a configuration in which a steel plate or an FRP plate is fixed to a surface 22a of concrete 22 by adhesion.

[0076] The reinforcing member 26D of the composite segment 20D according to the fourth modification shown in Fig. 14 is an example of a configuration in which the reinforcing range is not limited to the surface on the tunnel inner side, but includes at least the surface on the tunnel inner side, and extends in the segment thickness (i.e., tunnel wall thickness) direction. In the present invention, it is sufficient to prevent a large amount of concrete from falling into the tunnel interior due to crushing or splitting failure, so the concrete inside the tunnel can be prevented from falling by reinforcing at least the inner surface without being limited to a covering method, but the same effect can be obtained even with the reinforcing member 26D extending in the segment thickness direction as in the fourth modification. Note that the reinforcing member 26D shown in Fig. 14 has a thickness that extends to a position reaching the skin plate 25, but it may have a thickness up to the middle of the thickness direction.

[0077] Furthermore, within the scope of the present invention, the components in the above-described embodiments can be appropriately replaced with well-known components. [Explanation of symbols]

[0078] 1. Tunnel 10, 10A~10C segments 10a Tunnel inner surface 10b Tunnel exterior 10c Segment joint surface 10d Ring joint surface 11, 11A to 11C, 12 Reinforcing member 11a Inner surface 20, 20A-20D synthetic segments 26, 26A to 26D Reinforcing members P0 Tunnel zenith R1 Instep Ring R2 Otsu Ring X1 Tunnel circumferential direction X2 Tunnel axis direction

Claims

1. A segment installed in a tunnel with a circular cross section, with concrete exposed on the inner surface of the tunnel, A segment in which a reinforcing member is provided, including at least a portion of the tunnel inner surface side, in a first reinforcement range of at least one of 30° to 60° and -30° to -60° from the tunnel top in the tunnel circumferential direction.

2. The tunnel segments are staggered, and a first segment joint that connects the segment ends to each other is arranged in the first reinforcement range in the tunnel circumferential direction; 2. The segment according to claim 1, wherein the reinforcing member is provided in at least an area including the first segment joint in the tunnel circumferential direction and an area connected to the segment body of an adjacent ring in the tunnel axial direction relative to the area including the first segment joint.

3. The tunnel segments are staggered, and a first segment joint that connects the segment ends in the tunnel circumferential direction is disposed in the first reinforcement area; The segment according to claim 1 , wherein the reinforcing member is provided on only a segment body of a ring adjacent in a tunnel axial direction to the first segment joint arranged in the first reinforcing range.

4. A segment installed in a tunnel with a circular cross section, with concrete exposed on the inner surface of the tunnel, A segment in which a reinforcing member is provided, including at least a portion of the tunnel inner surface side, in a second reinforcement range of at least one of 120° to 150° and -120° to -150° from the tunnel top in the tunnel circumferential direction.

5. The tunnel segments are staggered, and second segment joints that connect the segment ends to each other are arranged in the second reinforcement range in the tunnel circumferential direction; 5. The segment according to claim 4, wherein the reinforcing member is provided in at least an area including the second segment joint in the tunnel circumferential direction and in an area connected to the segment body of an adjacent ring in the tunnel axial direction relative to the area including the second segment joint.

6. The tunnel segments are staggered, and second segment joints that connect the segment ends to each other are arranged in the second reinforcement range in the tunnel circumferential direction; The segment according to claim 4 , wherein the reinforcing member is provided on only the segment body of a ring adjacent in the tunnel axial direction to the second segment joint arranged in the second reinforcing range.

7. The segment according to any one of claims 1 to 6, wherein the reinforcing length of the reinforcing member extending in the circumferential direction of the tunnel is equal to or greater than the segment girder height and is in the range of an angle of 30° or less in the circumferential direction of the tunnel.

8. The segment according to claim 7 , wherein the reinforcing length of the reinforcing member is greater than or equal to two times and less than or equal to four times the segment girder height.

9. The segment according to claim 1 , wherein an inner circumferential surface of the reinforcing member is flush with an inner surface of the tunnel.

10. A method for manufacturing a segment that is provided in a tunnel having a circular cross section, and in which a reinforcing member is provided in a first reinforcing range that is at least one of 30° to 60° and −30° to −60° from the tunnel vertex in the tunnel circumferential direction, the first reinforcing range including at least a part of the tunnel inner surface side of the segment, pouring concrete into the arc-shaped plate-shaped frame so that a portion of the concrete is exposed on the inner surface; a step of reinforcing the first reinforcement area by providing a reinforcing member including at least a part of the segment on the tunnel inner surface side; A method for manufacturing a segment comprising the steps of:

11. A method for manufacturing a segment that is provided in a tunnel having a circular cross section, and in which a reinforcing member is provided in at least one second reinforcing range of 120° to 150° and -120° to -150° from the tunnel vertex in the tunnel circumferential direction, the second reinforcing range including at least a part of the tunnel inner surface side of the segment, pouring concrete into the arc-shaped plate-shaped frame so that a portion of the concrete is exposed on the inner surface; a step of reinforcing the second reinforcement area by providing a reinforcing member including at least a part of the tunnel inner surface side of the segment; A method for manufacturing a segment comprising the steps of:

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