Ladder sleepers for ballast ladder tracks

Abstract

To provide a ladder sleeper 10 for ballast ladder track that can suppress the occurrence of cracks and improve productivity.SOLUTION: A ladder sleeper 10 for a ballast ladder track has a pair of vertical beams 12a, 12b and a protrusion 20. The pair of vertical beams 12a, 12b are arranged to extend in the X direction below a pair of rails and also extending in the X direction. The protrusion 20 protrudes in the Y direction from the vicinity of the ends of the pair of vertical beams 12a, 12b in the X direction. The protrusion 20 protrudes to at least one of the inner and outer sides of the pair of vertical beams 12a, 12b in the Y direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] An embodiment of the present invention relates to a ladder sleeper for a ballast ladder track. [Background technology]

[0002] Ladder sleepers for ballasted-ladder track have been put to practical use with the aim of reducing the labor required for maintaining ballasted track. A ladder sleeper is a ladder-shaped sleeper in which a pair of long vertical beams made of prestressed concrete (PC) are placed along the rails and connected by steel joints.

[0003] The ends of the vertical beams of ladder sleepers for ballast ladder track are prone to sinking into the ballast track bed due to the wheel load of railway vehicles. For this reason, end closure beams are provided at the ends of ladder sleepers. The end closure beams are placed across a pair of vertical beams. The end closure beams increase the pressure-receiving area of ​​the ladder sleeper against the ballast, suppressing the sinking of the ends of the vertical beams.

[0004] The basic structure of end-closed beams is a reinforced concrete structure. However, to prevent cracks in end-closed beams, unbonded prestressing steel members are used to provide auxiliary prestress (post-tensioning). The construction method for end-closed beams is as follows. First, the formwork for the area is assembled and the rebar is placed. Next, the prestressing steel members with unbonded surfaces are placed in the designated positions. Next, the prestressing steel members are tensioned primarily to remove slack. Next, concrete is poured and allowed to harden, and prestressing is applied to the longitudinal beams. Next, the prestressing steel members are tensioned a second time to provide prestressing to the end-closed beams. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2012-136854 A Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, the process of applying prestress to the end closure beam is complicated and has poor productivity, i.e., the number of steps required to manufacture the ladder sleeper is increased, and the manufacturing time is lengthened. Even if the end closure beam is prestressed, cracks may occur in the end closure beam. For example, when uneven wheel loads act on a pair of longitudinal beams, excessive tension acts on the end closure beam, causing cracks.

[0007] The problem to be solved by the present invention is to provide a ladder sleeper for a ballast ladder track that is capable of suppressing the occurrence of cracks and improving productivity. [Means for solving the problem]

[0008] The ladder sleeper for a ballast ladder track of the present invention is disposed below a pair of rails extending in a first direction, and has a pair of longitudinal beams extending in the first direction, and protrusions protruding in the up-down direction and in a second direction intersecting the first direction from the vicinity of the ends of the pair of longitudinal beams in the first direction. The protrusions protrude at least to either the inside or the outside of the pair of longitudinal beams in the second direction. The protrusion is not disposed across a pair of vertical beams. Therefore, even if the wheel load acts unevenly on the pair of vertical beams, excessive tension is not applied to the protrusion. Therefore, the occurrence of cracks can be suppressed. Accordingly, a general reinforced concrete structure can be adopted for the protrusion. Therefore, productivity can be improved.

[0009] The protrusions may protrude both inward and outward in the second direction of the pair of longitudinal beams. This increases the area of ​​the ladder sleeper's end in the first direction that receives pressure from the ballast bed. This eliminates the need to increase the amount of protrusion in the second direction, thereby suppressing cracks in the protrusion.

[0010] The protrusion may protrude toward only one of the inner side and the outer side in the second direction of the pair of longitudinal beams. The protrusion may have a length in the first direction greater than a length in the second direction. This makes it possible to provide a space on the other of the inside and outside of the pair of longitudinal beams in the second direction. Also, a pressure-receiving area from the ballast bed at the end of the ladder sleeper in the first direction is ensured.

[0011] Chamfers may be formed at both corners in the second direction on the upper surfaces of the pair of vertical beams. The protrusions may be disposed below the positions of the lower ends of the chamfers. As a result, the corners of the vertical beams are chamfered even at the positions where the protrusions are formed, thereby preventing chipping of the corners of the vertical beams.

[0012] The joint member is disposed on the inner side of the pair of longitudinal beams in the second direction and connects the pair of longitudinal beams in the second direction. The joint member may be formed of a steel bar. Steel bars are inexpensive, which reduces the manufacturing costs of ladder sleepers.

[0013] The length of the protrusion in the first direction at the base end may be equal to the length of the protrusion in the first direction at the tip end. As a result, the end face of the protrusion in the first direction is disposed perpendicular to the first direction. Therefore, the protrusion exerts a vertical resistance force against the force in the first direction acting on the vertical beam. This makes it possible to suppress the ladder sleeper from shifting in the first direction.

[0014] The length of the protrusion in the first direction at the base end may be greater than the length of the protrusion in the first direction at the tip end. This increases the section modulus at the base end of the protrusion. Although the protrusion is a cantilever beam, the large section modulus at the base end suppresses cracking. Effect of the Invention

[0015] The ladder sleeper for ballast ladder track of the present invention has a protrusion that protrudes from at least one of the inside and outside of the pair of longitudinal beams in the second direction. The protrusion is not disposed across the space between the pair of longitudinal beams. This makes it possible to suppress the occurrence of cracks. A general reinforced concrete structure can be adopted for the protrusion, which improves productivity. [Brief description of the drawings]

[0016] [Figure 1] A perspective view of the ballast ladder track. [Diagram 2] FIG. 2 is a plan view of a ladder sleeper for a ballast ladder track according to an embodiment. [Diagram 3] FIG. 3 is a plan sectional view of part P in FIG. 2 . [Figure 4] Front view of ladder sleeper for ballast ladder track. [Diagram 5] FIG. 11 is a partial plan view of a ladder sleeper for a ballast ladder track according to a first modified example of an embodiment. [Figure 6] FIG. 11 is a partial plan view of a ladder sleeper for a ballast ladder track according to a second modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, a ladder sleeper for a ballast ladder track according to an embodiment will be described with reference to the drawings. FIG. 1 is a perspective view of a ballast ladder track. The ballast ladder track 1 is a track in which ladder sleepers for ballast ladder track (hereinafter sometimes simply referred to as "ladder sleepers") 10 are laid on a ballast track bed 3. The ladder sleepers 10 are ladder-shaped vertical sleepers arranged directly below the rails 5. The rails 5 are fixed to the ladder sleepers 10 by fastening devices 6.

[0018] In this application, the Z direction, X direction, and Y direction of the Cartesian coordinate system are defined as follows. The Z direction is the vertical direction, and the +Z direction is the upward direction. The X direction (first direction) is the direction in which the rail 5 extends. The Y direction (second direction) is the direction perpendicular to the Z direction and the X direction. The X direction and the Y direction are horizontal directions.

[0019] 2 is a plan view of a ladder sleeper for a ballast ladder track according to an embodiment. The ladder sleeper 10 has a longitudinal beam 12, a joint member 14, and a protrusion 20. The ladder sleeper 10 is formed in a ladder shape by rigidly connecting a pair of longitudinal beams 12a, 12b with a plurality of joint members 14.

[0020] The vertical beam 12 extends in the X direction. The vertical beam 12 is made of prestressed concrete (PC). PC is concrete prestressed by prestressing steel. A pair of vertical beams 12a, 12b are arranged parallel to each other with a gap in the Y direction. Mounting holes 16 for mounting a fastening device 6 (see FIG. 2) are formed on the upper surface of the vertical beam 12. The mounting holes 16 are arranged at positions corresponding to both sides of the rail 5 (see FIG. 2) in the Y direction. A plurality of mounting holes 16 are arranged at equal intervals along the X direction. The number of fastening devices 6 and mounting holes 16 in the X direction is not limited to the examples in the figures.

[0021] The joint member 14 is formed of a steel member such as a steel pipe or a steel rod. For example, the joint member 14 is formed of a straight deformed steel bar extending in the Y direction. For example, the deformed steel bar is D41 with a nominal diameter of 41 mm. The joint member 14 is disposed between a pair of vertical beams 12a, 12b. Both ends of the joint member 14 in the Y direction are embedded inside the pair of vertical beams 12a, 12b. A plurality of joint members 14 (three in the example of FIG. 2) are disposed in parallel with an interval in the X direction. For example, a plurality of joint members 14 are disposed at equal intervals between both ends of the vertical beam 12 in the X direction. The joint member 14 may be formed of a steel pipe filled with mortar inside.

[0022] The protrusion 20 increases the pressure receiving area from the ballast track bed 3 at the X-direction end of the vertical beam 12. The protrusion 20 suppresses the X-direction end of the vertical beam 12 from sinking into the ballast track bed 3. The protrusion 20 may be called a subsidence suppressing portion, an overhanging portion, a widening portion, a protrusion, or the like. The protrusions 20 are disposed near both ends in the X direction of the vertical beam 12. The protrusions 20 protrude in the Y direction from the vertical beam 12. The protrusions 20 protrude both inward and outward in the Y direction of the pair of vertical beams 12a, 12b.

[0023] When a railway vehicle travels on the ballast ladder track 1, a force (wheel load) in the Z direction acts on the vertical beam 12. A conventional end closure beam 90 is arranged straddling a pair of vertical beams 12a, 12b. In contrast, the protrusion 20 is not arranged straddling a pair of vertical beams 12a, 12b. Therefore, even if a force in the Z direction acts unevenly on the pair of vertical beams 12a, 12b, excessive tension does not act on the protrusion 20. Therefore, cracks are less likely to occur in the protrusion 20. As a result, maintenance management after installation of the ladder sleeper 10 becomes easier.

[0024] 3 is a plan cross-sectional view of part P in FIG. 2. The projection 20 projects from the vertical beam 12 in the Y direction by a projection amount Py. For example, the projection amount Py is about 200 mm. The projection 20 is a cantilever beam, but since the projection amount Py is small, cracks are unlikely to occur. The distance between the tips of a pair of projections 20 projecting outward in the Y direction from a pair of vertical beams 12a, 12b corresponds to the width W of the ladder sleeper 10 (see FIG. 2). The width W of the ladder sleeper 10 is equivalent to the length of a conventional horizontal sleeper. Therefore, the ladder sleeper 10 can be laid on a conventional ballast track bed 3.

[0025] Thus, cracks are less likely to occur in the protrusion 20. While prestress is applied to the conventional end-closed beam 90, the protrusion 20 is a typical reinforced concrete (RC) structure. The primary and secondary tensioning of the PC steel members, which was necessary in the manufacturing process of the conventional end-closed beam 90, is not required in the manufacturing process of the protrusion 20. Therefore, the productivity of the ladder sleeper 10 is improved.

[0026] Main reinforcement bars 12m and stirrups 12s are arranged in the core of the vertical beam 12. The main reinforcement bars 12m are made of PC steel and extend in the X direction. The stirrups 12s are arranged so as to surround the multiple main reinforcement bars 12m. The stirrups 12s are arranged at a high density at the end of the vertical beam 12 in the X direction.

[0027] The arrangement of the reinforcement of the protrusion 20 is restricted by the relationship with the arrangement of the reinforcement of the X-direction end of the vertical beam 12. The distance E from the X-direction end of the vertical beam 12 to the protrusion 20 is the shortest distance within the range in which the reinforcement of the protrusion 20 can be arranged. This makes it possible to prevent the X-direction end of the vertical beam 12 from sinking into the ballast track bed 3.

[0028] As described above, when a railway vehicle travels on the ballast ladder track 1, a force in the Z direction acts on the longitudinal beam 12. The force in the Z direction acting on the longitudinal beam 12 becomes large at the position of the mounting hole 16 where the fastening device 6 is disposed. The protrusion 20 is disposed near the mounting hole 16 at the end of the longitudinal beam 12 in the X direction. This makes it possible to prevent the end of the longitudinal beam 12 in the X direction from sinking into the ballast track bed 3.

[0029] The width Px of the protrusion 20 in the X-direction is equal to the protrusion amount Py. The product of the protrusion amount Py and the width Px is the pressure-receiving area of ​​the bottom surface of the protrusion 20. Because the protrusion amount Py and width Px of the protrusion 20 are small, the planar area of ​​one protrusion 20 is small. Even when tamping work is performed on the ballast track bed 3 after the ladder sleepers 10 are laid, the protrusions 20 are unlikely to interfere with the tamping work.

[0030] The width Px of the protrusion 20 is equal to the width of the end closure beam 90. The sum of the pressure-receiving areas of the multiple protrusions 20 of the ladder sleeper 10 is greater than the sum of the pressure-receiving areas of the end closure beams 90. This makes it possible to prevent the X-direction ends of the vertical beams 12 from sinking into the ballast track bed 3. Accordingly, there is no need to increase the protrusion amount Py of the protrusion 20 in the Y direction, and therefore the occurrence of cracks in the protrusion 20 is suppressed.

[0031] The X-direction width Px2 at the base end of the protrusion 20 (the connection portion with the vertical beam 12) is equal to the X-direction width Px1 at the tip end of the protrusion 20. The protrusion 20 is square or rectangular in plan view. The X-direction end face 22 of the protrusion 20 is disposed perpendicular to the X direction. The sum of the Y-direction lengths of the multiple protrusions 20 of the ladder sleeper 10 is greater than the sum of the Y-direction lengths of the end closure beams 90.

[0032] When a railway vehicle travels on the ballast ladder track 1, a force in the X direction also acts on the longitudinal beam 12. When a force in the X direction acts on the longitudinal beam 12, the ladder sleeper 10 may be displaced in the X direction. The X-direction end face 22 of the protrusion 20 is disposed perpendicular to the X direction. The X-direction end face 22 of the protrusion 20 exerts a vertical resistance force against the X-direction force acting on the longitudinal beam 12. This makes it possible to suppress the ladder sleeper 10 from being displaced in the X direction.

[0033] Fig. 4 is a front view of a ladder sleeper for a ballast ladder track. A chamfer 13 is formed at both end corners in the Y direction on the upper surface of the vertical beam 12. The chamfer 13 prevents chipping of the corners of the vertical beam 12. The protrusion 20 is positioned below the position of the lower end of the chamfer 13 of the vertical beam 12. As a result, the chamfer 13 is formed at the corners of the vertical beam 12 even at the formation position of the protrusion 20. The height Pz of the protrusion 20 in the Z direction is smaller than the height Bz of the vertical beam 12 in the Z direction. A chamfer 23 is also formed at the tip corner in the Y direction on the upper surface of the protrusion 20.

[0034] As described above in detail, the ladder sleeper 10 for a ballast ladder track of the embodiment has a pair of longitudinal beams 12a, 12b and a protrusion 20. The pair of longitudinal beams 12a, 12b are disposed below the pair of rails 5 extending in the X direction and extend in the X direction. The protrusion 20 protrudes in the Y direction from the vicinity of the ends of the pair of longitudinal beams 12a, 12b in the X direction. The protrusion 20 protrudes at least on either the inner side or the outer side in the Y direction of the pair of longitudinal beams 12a, 12b.

[0035] The protrusion 20 is not disposed across the pair of vertical beams 12a, 12b. Even if a force in the Z direction acts unevenly on the pair of vertical beams 12a, 12b, an excessive tension does not act on the protrusion 20. Therefore, the occurrence of cracks can be suppressed. Accordingly, a general reinforced concrete (RC) structure can be adopted for the protrusion 20. Therefore, productivity can be improved.

[0036] The projections 20 protrude both inward and outward in the Y direction of the pair of vertical beams 12a, 12b. This increases the area of ​​the longitudinal beam 12 that receives pressure from the ballast bed 3 at the end in the X direction. Therefore, it is not necessary to increase the protrusion amount Py of the protrusion 20 in the Y direction. Therefore, the occurrence of cracks in the protrusion 20 is suppressed.

[0037] Chamfers 13 are formed at both corners in the Y direction on the upper surfaces of the pair of vertical beams 12a, 12b. The protrusions 20 are disposed below the position of the lower ends of the chamfers 13. As a result, chamfers 13 are formed on the corners of the vertical beams 12 even at the positions where the projections 20 are formed. Therefore, chipping of the corners of the vertical beams 12 is suppressed.

[0038] The joint member 14 is disposed on the inner side of the pair of vertical beams 12a, 12b in the Y direction and connects the pair of vertical beams 12a, 12b in the Y direction. The joint member 14 is made of a steel bar. Since steel bars are inexpensive, the manufacturing costs of the ladder sleeper 10 are reduced.

[0039] The width Px2 of the protrusion 20 in the X direction at the base end is equal to the width Px1 of the protrusion 20 in the X direction at the tip end. As a result, the X-direction end face 22 of the projection 20 is disposed perpendicular to the X-direction. The X-direction end face 22 of the projection 20 exerts a vertical resistance force against the X-direction force acting on the vertical beam 12. As a result, it is possible to suppress the ladder sleeper 10 from shifting in the X-direction.

[0040] (First Modification) 5 is a partial plan view of a ladder sleeper for a ballast ladder track according to a first modified example of the embodiment. The first modified example differs from the embodiment in that the protrusions 20B are arranged only on the outer sides of the pair of longitudinal beams 12a, 12b in the Y direction. Explanation of the first modified example that is the same as the embodiment will be omitted.

[0041] The protrusion 20B protrudes only outside the pair of vertical beams 12a, 12b in the Y direction. This allows a space to be provided inside the pair of vertical beams 12a, 12b in the Y direction. For example, when tamping ballast is performed inside the pair of vertical beams 12a, 12b in the Y direction, the protrusion 20B does not interfere with the tamping work.

[0042] The protrusion amount Py of the protrusion 20B in the Y direction is equivalent to that of the above-mentioned embodiment. The width Px of the protrusion 20 in the X direction is greater than the protrusion amount Py. For example, the width Px of the protrusion 20 is about twice the protrusion amount Py. The product of the protrusion amount Py and the width Px is the pressure-receiving area of ​​the bottom surface of the protrusion 20. The sum of the pressure-receiving areas of the multiple protrusions 20B of the ladder sleeper 10B is equivalent to that of the above-mentioned embodiment. As a result, as in the embodiment, it is possible to suppress the sinking of the X-direction end of the vertical beam 12 into the ballast track bed 3.

[0043] The protrusion 20B of the first modified example protrudes only outside the pair of longitudinal beams 12a, 12b in the Y direction. In contrast, the protrusion may protrude only inside the pair of longitudinal beams 12a, 12b in the Y direction. In this case, a space can be provided outside the pair of longitudinal beams 12a, 12b in the Y direction. Even if there is a restriction on the width of the ballast track bed 3 in the Y direction, it is easy to lay ladder sleepers on the ballast track bed 3.

[0044] (Second Modification) 6 is a partial plan view of a ladder sleeper for a ballast ladder track according to a second modified example of the embodiment. The second modified example differs from the embodiment in that the width Px2 in the X direction at the base end of the projection 20C is larger than the width Px1 in the X direction at the tip end of the projection 20C. Explanation of the second modified example that is the same as the embodiment will be omitted.

[0045] The width Px2 in the X direction at the base end of the protrusion 20C is larger than the width Px1 in the X direction at the tip end of the protrusion 20C. The protrusion 20 is trapezoidal in plan view. This increases the section modulus at the base end of the protrusion 20C. Although the protrusion 20C is a cantilever beam, the large section modulus at the base end makes it less likely to crack.

[0046] Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and changes, combinations, deletions, etc. of the configuration are also included within the scope that does not deviate from the gist of the present invention. [Explanation of symbols]

[0047] X...first direction, Y...second direction, Z...up and down direction, 1...ballast ladder track, 5...rail, 10...ladder sleeper for ballast ladder track, 12, 12a, 12b...longitudinal beams, 13...chamfer, 14...joint, 20, 20B, 20C...protrusions.

Claims

1. A pair of longitudinal beams extending in a first direction and disposed in parallel below a pair of rails extending in the first direction; and protrusions protruding in a second direction intersecting the up-down direction and the first direction only from the vicinity of both ends of the pair of vertical beams in the first direction, The protrusions protrude toward both the inside and the outside of the pair of longitudinal beams in the second direction, The sum of the lengths of the plurality of protrusions in the second direction is greater than twice the interval between the pair of longitudinal beams. Ladder sleepers for ballast ladder track.

2. Chamfers are formed at both end corners in the second direction on the upper surfaces of the pair of vertical beams, The protrusion is disposed below the lower end of the chamfer.

2. A ladder sleeper for a ballast ladder track according to claim 1.

3. A joint member is disposed on the inner side of the pair of longitudinal beams in the second direction and connects the pair of longitudinal beams in the second direction, The joint material is formed of a steel bar.

3. A ladder sleeper for a ballast ladder track according to claim 1 or 2.

4. The length of the protrusion in the first direction at the base end portion is equal to the length of the protrusion in the first direction at the tip end portion. A ladder sleeper for a ballast ladder track according to any one of claims 1 to 3.

5. The length of the protrusion in the first direction at the base end portion is greater than the length of the protrusion in the first direction at the tip end portion. A ladder sleeper for a ballast ladder track according to any one of claims 1 to 3.

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