JP2021134495A - Ladder sleeper - Google Patents

Abstract

To provide a ladder sleeper 10 enabling cost reduction.SOLUTION: Bracing 14 is formed of a linear steel bar whose both ends are embedded in a pair of vertical beams 12. The bracing 14 is entirely subject to rust proofing treatment. Stirrups 12r are disposed in the pair of vertical beams 12 so as to be spaced apart from each other in an X direction. The density in the X direction of the stirrups 12r at a vicinity area 17d of the bracing 14 is higher than the density in the X direction of the stirrups 12r at an intermediate area 17c between the bracings 14 that are adjacent in the X direction. A spiral reinforcement 12s is disposed around the bracing 14 embedded in the pair of vertical beams 12.SELECTED DRAWING: Figure 3

Description

Embodiments of the present invention relate to ladder sleepers.

Ladder sleepers have been put into practical use for the purpose of track maintenance and labor saving. A ladder sleeper is a ladder-shaped sleeper in which long prestressed concrete (PC) vertical beams are arranged along a rail and a pair of vertical beams are connected by a steel joint.

The joint material is provided to maintain the gauge of the ladder sleepers. A special weather-resistant steel pipe is used as the joint material. The inside of the steel pipe is filled with mortar to prevent local buckling against the bending deformation of the steel pipe assumed in the design. The ends of the steel pipes are flattened in order to secure the fixing to the concrete vertical beams and prevent the steel pipes from coming off.

Japanese Unexamined Patent Publication No. 2008-184863

As described above, a special steel pipe is used as the joint material, and the joint material is manufactured through a complicated process. Therefore, it is required to reduce the cost of the joint material.

An object to be solved by the present invention is to provide a ladder sleeper that can reduce the cost.

The ladder sleepers in the present invention are arranged below a pair of rails extending in the first direction, and are composed of a pair of vertical beams extending in the first direction and a pair of vertical beams extending in the vertical direction and in the second direction intersecting the first direction. It has a joint that is arranged inside and joins a pair of vertical beams in a second direction. The joint is made of straight steel bars with both ends embedded in a pair of vertical beams. The joint material is entirely rust-proofed. Inside the pair of vertical beams, stirrups are arranged at intervals in the first direction. The density of the stirrup in the first direction in the region near the splicing material is higher than the density in the first direction of the stirrup in the intermediate region of the splicing material adjacent to the first direction. Spiral bars are placed around the joints embedded in the pair of vertical beams.

Since the joint material is made of straight steel bar, the cost of the ladder sleepers can be reduced as compared with the case where the joint material in which the end portion of the steel pipe is flattened is adopted. Since the joint material is rust-proofed, the running cost of the ladder sleepers can be reduced. Since the entire joint material is subjected to the rust preventive treatment, the rust preventive treatment work is simplified as compared with the case where a part of the joint material is subjected to the rust preventive treatment, and the cost of the ladder sleepers can be reduced. .. Even if the splicing material is made of straight steel bars, the pull-out strength of the splicing material from the vertical beam is ensured. Since the density of the stirrup in the region near the joint material in the first direction is high, cracks along the first direction are suppressed in the region near the joint material. Since the spiral streaks are arranged around the joint material, cracks along the second direction are suppressed at the embedding position of the joint material.

The rust preventive treatment is an epoxy powder coating treatment.
As a result, rusting of the joint material is suppressed, and the electrical insulation performance of the joint material is improved. In addition, the cost of ladder sleepers can be reduced.

The pair of vertical beams have mounting holes for mounting fastening devices that secure the rails. The splicing material is arranged in the middle of the mounting holes adjacent to each other in the first direction.
This makes it easier to place the stirrup and spiral streaks while avoiding interference with the mounting holes 16.

The steel bar has a nominal diameter of 41 mm or more.
As a result, the pull-out strength of the joint member 14 from the vertical beam 12 can be ensured.

Three or more joints are arranged side by side at equal intervals in the first direction.
The holding force of the gauge is shared by the three or more joint members 14. Therefore, the pull-out strength of each joint material 14 is ensured.

The pair of vertical beams has a pair of end-closing beams connecting the pair of vertical beams in the second direction at both ends in the first direction. Three or more joints are arranged at equal intervals between a pair of end-closing beams in the first direction.
The pair of end closing beams 90 also share the holding force of the gauge. Therefore, the pull-out strength of each joint material 14 is ensured.

Since the joint material is made of straight steel bar, the cost of the ladder sleepers can be reduced as compared with the case where the joint material in which the end portion of the steel pipe is flattened is adopted. Since the joint material is rust-proofed, the running cost of the ladder sleepers can be reduced. Since the entire joint material is subjected to the rust preventive treatment, the rust preventive treatment work is simplified as compared with the case where a part of the joint material is subjected to the rust preventive treatment, and the cost of the ladder sleepers can be reduced. .. Even if the joint is made of straight steel bars, the pull-out strength of the joint from the vertical beam is ensured.

A perspective view of the ballast / ladder track. Top view of the ladder sleepers of the embodiment. FIG. 2 is a plan sectional view of a portion P in FIG. Explanatory drawing of drawing test of joint material. The plan view of the ladder sleeper of the 1st modification of embodiment.

Hereinafter, the ladder sleepers of the embodiment will be described with reference to the drawings. In the embodiment, a ladder sleeper for a ballast / ladder track will be described as an example.
FIG. 1 is a perspective view of the ballast / ladder track. The ballast-ladder track 1 is a track in which a ladder sleeper 10 is laid on a ballast track bed 3. The ladder sleeper 10 is a ladder-shaped vertical sleeper arranged directly below the rail 5. The rail 5 is fixed to the ladder sleepers 10 by the fastening device 6.

In the present application, the Z direction, the X direction and the 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 a direction orthogonal to the Z direction and the X direction. The X and Y directions are horizontal.

FIG. 2 is a plan view of the ladder sleepers of the embodiment. The ladder sleeper 10 has a vertical beam 12, an end closing beam 90, and a joint member 14. The ladder sleepers 10 are formed in a ladder shape by rigidly connecting a pair of vertical beams 12a and 12b with a plurality of joint members 14.

The vertical beam 12 extends in the X direction. The vertical beam 12 is formed of prestressed concrete (PC). PC is concrete prestressed by PC steel. A pair of vertical beams 12a and 12b are arranged in parallel at intervals in the Y direction. A mounting hole 16 for mounting the fastening device 6 (see FIG. 1) is 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. 1) 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 each figure.

The end closing beam 90 is arranged so as to straddle the pair of vertical beams 12a and 12b, and connects the pair of vertical beams 12a and 12b in the Y direction. The basic structure of the end closing beam 90 is a reinforced concrete structure. However, in order to prevent the end closing beam 90 from cracking, prestress (post-tension type) is additionally applied by the unbonded PC steel material. A pair of end closing beams 90 are arranged at both ends of the pair of vertical beams 12a and 12b in the X direction. The end closing beam 90 increases the pressure receiving area of the ladder sleeper 10 against the ballast and suppresses the sinking of the end portion of the vertical beam 12.

The joint member 14 is arranged so as to straddle the pair of vertical beams 12a and 12b. A plurality of (three in the example of FIG. 2) joints 14 are arranged side by side at equal intervals in the X direction. A plurality of joint members 14 are arranged side by side between a pair of end closing beams 90 in the X direction.
The joint member 14 is formed of a linear deformed steel bar extending in the Y direction. For example, the deformed steel bar is D41 with a nominal diameter of about 41 mm. It is desirable that the nominal diameter of the deformed steel bar is 41 mm or more. For example, the deformed steel bar may be D51 having a nominal diameter of about 51 mm. Both ends of the joint 14 in the Y direction are embedded inside the pair of vertical beams 12a and 12b. For example, when the width of the vertical beam 12 in the Y direction is 460 mm, the fixing length (embedded length) of the end portion of the joint member 14 is 400 mm.

Rust prevention treatment is applied to the entire surface of the joint material 14. For example, the rust preventive treatment is an epoxy powder coating treatment. The rust preventive treatment may be a room temperature metal spraying system (MS method, zinc and aluminum are sprayed to form a rust preventive film). By applying the rust preventive treatment, rusting of the joint material 14 exposed between the pair of vertical beams 12a and 12b is suppressed. By applying the rust preventive treatment to the entire joint material 14, even if the vertical beam 12 is cracked, the rusting of the joint material 14 embedded inside the vertical beam 12 is suppressed. By applying the rust preventive treatment to the entire joint material 14, the rust preventive treatment work is simplified as compared with the case where a part of the joint material 14 is subjected to the rust preventive treatment.

FIG. 3 is a plan sectional view of a portion P in FIG. As shown in FIG. 3, a main bar 12 m and a stirrup 12r are arranged at the core of the vertical beam 12. The main bar 12 m is formed of a stranded PC steel wire and extends in the X direction. The stirrup 12r is arranged in the YZ plane so as to surround the plurality of main bars 12m. A plurality of stirrups 12r are arranged at intervals in the X direction.

The joint member 14 is arranged between the mounting holes 16 adjacent to each other in the X direction. The density of the stirrup 12r in the first region 18d in the X direction is higher than the density in the second region 18c. The first region 18d is a region inside the mounting holes 16 adjacent to each other in the X direction, and is a region in which the joint member 14 is arranged. The second region 18c is a region inside the mounting holes 16 adjacent to each other in the X direction, and is a region in which the joint member 14 is not arranged. In other words, the density of the stirrup 12r in the X direction in the vicinity region 17d of the joint member 14 is larger than the density in the intermediate region 17c of the joint members 14 adjacent to each other in the X direction. The pitch of the stirrup 12r in the X direction in the vicinity region 17d of the joint member 14 is half the pitch of the intermediate region 17c. That is, the density of the stirrup 12r in the X direction in the vicinity region 17d of the joint material 14 is twice the density of the intermediate region 17c.

FIG. 4 is an explanatory diagram of a pull-out test of the joint material. A full-scale model test piece 910 of the ladder sleeper was prepared by making the density of the stirrup 12r in the X direction in the vicinity region 17d shown in FIG. 3 the same as the density in the intermediate region 17c. With respect to the test body 910, a pull-out test of the joint material 14 from the vertical beam 12 was carried out. When the pull-out load became large, as shown in FIG. 4, cracks Cx along the X direction were generated in the region near the joint member 14. The crack Cx along the X direction is generated by the tensile stress in the Y direction of the concrete. As shown in FIG. 3, in the ladder sleeper 10 of the embodiment, the density of the stirrup 12r in the X direction in the vicinity region 17d of the joint lumber 14 is large. The stirrup 12r extends in the Y direction and suppresses the tensile stress of the concrete in the Y direction. As a result, crack Cx along the X direction is suppressed.

As shown in FIG. 3, the end portion of the joint member 14 is embedded in the vertical beam 12. Spiral muscles 12s are arranged around the ends of the lumber 14. The spiral muscles are formed in a spiral shape and surround the end portion of the joint material 14.
The test body 910 shown in FIG. 4 does not have a spiral muscle. When the pull-out load of the joint material 14 became large, crack Cy along the Y direction was generated at the embedded position of the joint material 14. The crack Cy along the Y direction is generated by the tensile stress in the X direction of the concrete. As shown in FIG. 3, in the ladder sleeper 10 of the embodiment, the spiral muscle 12s is arranged around the end portion of the joint member 14. The spiral streaks 12s extend in the X direction and suppress the tensile stress in the X direction of the concrete. As a result, crack Cy along the Y direction is suppressed.

As described above, the stirrup 12r is densely arranged in the vicinity region 17d of the joint material 14. Spiral muscles 12s are arranged around the ends of the lumber 14. The stirrup 12r and the spiral bar 12s need to be arranged so as to avoid interference with the mounting holes 16. The joint member 14 is arranged in the middle of the mounting holes 16 adjacent to each other in the X direction. This makes it easier to arrange the stirrup 12r and the spiral bar 12s while avoiding interference with the mounting hole 16.

The performance test of the ladder sleeper 10 of the embodiment will be described.
Lateral pressure (horizontal force) acts on the rail 5 from the wheels as the railroad vehicle travels. The joint lumber 14 is required to maintain the gauge against the lateral pressure. In order to maintain the gauge, it is necessary to secure the pull-out strength of the joint member 14 from the vertical beam 12. The guideline value of the guaranteed pull-out load of the joint material 14 is set to 60 kN with reference to the design lateral pressure of the PC sleepers for curves shown in JIS E1201 and 1202. The guideline value of the pull-out fracture load of the joint material 14 is set to 200 kN with reference to the design lateral pressure used in the design of the derailment prevention guard for measures against derailment during an earthquake.

Table 1 shows the results of the pull-out test of the lumber 14. A full-scale model test piece of the ladder sleeper 10 was prepared by using a D41 steel bar for the joint material 14. A pull-out test was carried out on three test pieces, and the crack generation load and the breaking load were measured. As a result, the average value of the crack generation load was 103 kN, and the minimum value was 84 kN. The minimum value of the crack generation load exceeded 60 kN, which is a guideline value for the guaranteed pull-out load of the joint material 14. On the other hand, the average value of the fracture load was 595 kN, and the minimum value was 572 kN. The minimum value of the breaking load exceeded 200 kN, which is a guideline value for the pull-out breaking load of the joint material 14. It is clear that steel bars such as D51 having a nominal diameter of 41 mm or more have a pull-out strength of D41 or more. From the above, it was confirmed that the pull-out strength of the joint material 14 can be ensured by using a steel bar having a nominal diameter of 41 mm or more for the joint material 14. As described above, the plurality of joint members 14 are arranged between the pair of vertical beams 12a and 12b. The plurality of joint members 14 share the holding force of the gauge. As the number of joints 14 increases, it becomes easier to secure the pull-out strength of the joints 14.
In this application, deformed steel bars (unprocessed) are used to increase pull-out resistance. Considering the reinforced concrete structure, it is considered that the fixing length to the vertical beam 12 needs to be longer than the width of the vertical beam 12, or it is necessary to hook and fix the deformed steel bar. However, it was confirmed in the test that the pull-out resistance can be secured with a fixing length shorter than the width of the vertical beam 12 by arranging the spiral bars 12s or the like.

The method of manufacturing the ladder sleeper 10 of the embodiment will be described.
First, the bottom slab of the vertical beam 12 is prepared, and the side inner frame is arranged. Next, the stirrup 12r is temporarily placed. Next, the PC steel stranded wire, the joint material 14, and the stirrup 12r are arranged. The PC steel stranded wire is arranged in the stirrup 12r via the vertical beam end face frame. A predetermined number of PC steel stranded wires are arranged above and below the joint lumber 14. The joint material 14 is arranged together with the spiral muscle 12s. Next, the PC steel stranded wire is temporarily tensioned. Specifically, the PC steel stranded wire is fixed to the fixing plate. After that, in order to eliminate the variation during the main tension, a predetermined tension is applied to the PC steel stranded wires one by one. Next, the tension jack is used to tension all the PC steel stranded wires at the same time.

Next, the stirrup 12r and the reinforcing bar are tied in place to assemble the reinforcing bar. Next, the embedding material and the spiral bar are arranged at the positions of the mounting holes 16 and mounted on the formwork. Next, the reinforcing bars of the end closing beam 90 are arranged. The reinforcing bars of the end closing beam 90 may be assembled in advance in a basket shape. A PC steel rod for applying prestress to the end closing beam 90 is temporarily arranged. Next, the remaining side outer frame of the vertical beam 12 and the formwork of the end closing beam 90 are assembled. Next, the PC steel rod of the end closing beam 90 is attached at a predetermined position and tightened to the extent that it does not loosen, and the primary tension is applied. Next, attach accessories such as hanging inserts. Then, concrete is placed.

After roughing (height adjustment) the concrete casting surface, the elastic material is attached in place as needed. Next, the casting surface is smoothly finished with a trowel. Next, curing that can secure the necessary strength at the time of introduction of prestress, such as high temperature promotion curing, is performed. When the required strength is developed, the end face frame and side frame of the vertical beam 12 are demolded. Also, remove the mounting bolts such as the embedding material. Next, the tension of the PC steel stranded wire is relaxed and prestress is introduced into the vertical beam 12. Next, the PC steel rod of the end closing beam 90 is secondarily strained. Specifically, after lifting the formwork from the ladder sleeper 10 to about 10 mm, the PC steel rod of the end closing beam 90 is strained. The formwork is lifted so that the chamfered portion of the vertical beam 12 does not collide with the formwork of the end closing beam 90 due to the tension of the PC steel rod.

Next, the end of the PC steel stranded wire is cut to finish the end face of the vertical beam 12. In addition, the end closing beam 90 is post-filled. Next, the product is cured for a period required for the development of the design standard strength. Finally, the necessary track member such as a cushioning material is attached to complete the ladder sleeper 10.

As described in detail above, the ladder sleeper of the embodiment has a pair of vertical beams 12a and 12b and a joint member 14. The pair of vertical beams 12a and 12b are arranged below the pair of rails 5 extending in the X direction and extend in the X direction. The joint member 14 is arranged inside the pair of vertical beams 12a and 12b in the Y direction intersecting the Z direction and the X direction, and joins the pair of vertical beams 12a and 12b in the Y direction. The joint member 14 is formed of a linear bar steel whose both ends are embedded in a pair of vertical beams 12a and 12b. The joint material 14 is entirely rust-proofed. Inside the pair of vertical beams 12a and 12b, stirrups 12r are arranged at intervals in the X direction. The density of the stirrup 12r in the X direction in the vicinity region 17d of the joint material 14 is larger than the density of the stirrup 12r in the X direction in the intermediate region 17c of the joint material 14 adjacent to the X direction. Spiral bars 12s are arranged around the joint members 14 embedded in the pair of vertical beams 12a and 12b.

Since the joint member 14 is formed of a linear steel bar, the cost of the ladder sleeper 10 can be reduced as compared with the case where a joint material in which the end portion of the steel pipe is flattened is adopted. Since the joint material is rust-proofed, the running cost of the ladder sleepers 10 can be reduced. Since the entire joint material 14 is subjected to the rust preventive treatment, the rust preventive treatment work is simplified as compared with the case where a part of the joint material 14 is subjected to the rust preventive treatment, and the cost of the ladder sleeper 10 is reduced. be able to. Even if the joint member 14 is made of a linear steel bar, the pull-out strength of the joint material 14 from the vertical beam 12 can be ensured. Since the density of the stirrup 12r in the X direction in the vicinity region 17d of the joint material 14 is high, crack Cx along the X direction is suppressed in the vicinity region 17d of the joint material 14. Since the spiral streaks 12s are arranged around the joint material 14, crack Cy along the Y direction is suppressed at the embedding position of the joint material 14.

The rust preventive treatment is an epoxy powder coating treatment.
As a result, rusting of the joint material 14 is suppressed, and the electrical insulation performance of the joint material 14 is improved. In addition, the cost of the ladder sleepers 10 can be reduced.

The pair of vertical beams 12a and 12b have mounting holes 16 for mounting the fastening device 6 for fixing the rail 5. The joint member 14 is arranged in the middle of the mounting holes 16 adjacent to each other in the X direction.
This makes it easier to arrange the stirrup 12r and the spiral bar 12s while avoiding interference with the mounting hole 16.

The steel bar has a nominal diameter of 41 mm or more.
As a result, the pull-out strength of the joint member 14 from the vertical beam 12 can be ensured.

Three or more joint members 14 are arranged side by side at equal intervals in the X direction.
The holding force of the gauge is shared by the three or more joint members 14. Therefore, the pull-out strength of the joint material 14 is ensured.

The pair of vertical beams 12a and 12b have a pair of end-closing beams 90 that connect the pair of vertical beams 12a and 12b in the Y direction at both ends in the X direction. Three or more joint members 14 are arranged side by side at equal intervals between a pair of end closing beams 90 in the X direction.
The pair of end closing beams 90 also share the holding force of the gauge. Therefore, the pull-out strength of each joint material 14 is ensured.

(First modification)
FIG. 5 is a plan view of the ladder sleeper of the first modification of the embodiment. In the embodiment, the ladder sleeper 10 for the ballast / ladder track has been described as an example. The ladder sleeper 10A of the first modification is different from the embodiment in that it is for a floating ladder track. The description of the first modification with respect to the same points as in the embodiment will be omitted.

The floating ladder track is a directly connected track having a structure in which the ladder sleepers are intermittently supported by a vibration-proof material or a vibration-proof device having low spring rigidity and floated from a concrete deck such as a viaduct. The ladder sleeper 10A for a floating ladder track does not have an end-closing beam because it is less necessary to consider the sinking of the end of the vertical beam 12.

The ladder sleeper 10A has a plurality of (three in the example of FIG. 5) joints 14. A plurality of joint members 14 are arranged between the pair of vertical beams 12a and 12b in parallel at equal intervals in the X direction. The joint member 14e arranged at the end in the + X direction is arranged between the first mounting hole 16e1 and the second mounting hole 16e2. The first mounting hole 16e1 is a mounting hole arranged at the end in the + X direction. The second mounting hole 16e2 is a mounting hole adjacent to the first mounting hole 16e1 in the −X direction. The splicing material arranged at the end in the −X direction is also arranged in the same manner.
The ladder sleeper 10A of the first modification also has the same effect as the ladder sleeper 10 of the embodiment.

Although one embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and the configuration is changed, combined, or deleted without departing from the gist of the present invention. Etc. are also included.

X ... 1st direction, Y ... 2nd direction, Z ... Vertical direction, 5 ... Rail, 6 ... Fastening device, 10,10A ... Ladder sleepers, 12, 12a, 12b ... Vertical beams, 12r ... Stirrup, 12s ... Spiral Reinforcement, 14 ... Joint material, 16 ... Mounting hole, 17d ... Near region, 17c ... Intermediate region, 90 ... End closed beam.

Claims (6)

A pair of vertical beams arranged below a pair of rails extending in the first direction and extending in the first direction,
It has a joint material that is arranged inside the pair of vertical beams in the vertical direction and a second direction that intersects the first direction, and that joins the pair of vertical beams in the second direction.
The joint material is formed of a straight steel bar having both ends embedded in the pair of vertical beams.
The joint material is rust-proofed as a whole.
Inside the pair of vertical beams, stirrups are arranged at intervals in the first direction.
The density of the stirrup in the first direction in the region near the splicing material is higher than the density of the stirrup in the first direction in the intermediate region of the splicing material adjacent to the first direction.
Spiral bars are arranged around the joint material embedded in the pair of vertical beams.
Ladder sleepers. The rust preventive treatment is an epoxy powder coating treatment.
The ladder sleeper according to claim 1. The pair of vertical beams have mounting holes for mounting fastening devices for fixing the rails.
The joint material is arranged in the middle of the mounting holes adjacent to each other in the first direction.
The ladder sleeper according to claim 1 or 2. The steel bar has a nominal diameter of 41 mm or more.
The ladder sleeper according to any one of claims 1 to 3. Three or more of the joint members are arranged side by side at equal intervals in the first direction.
The ladder sleeper according to any one of claims 1 to 4. The pair of vertical beams has a pair of end-closing beams connecting the pair of vertical beams in the second direction at both ends in the first direction.
Three or more of the joints are arranged side by side at equal intervals between the pair of end-closing beams in the first direction.
The ladder sleeper according to any one of claims 1 to 5.

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