CA2477887A1 - Rail sleeper and ballast-free track structure - Google Patents
Rail sleeper and ballast-free track structure Download PDFInfo
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- CA2477887A1 CA2477887A1 CA002477887A CA2477887A CA2477887A1 CA 2477887 A1 CA2477887 A1 CA 2477887A1 CA 002477887 A CA002477887 A CA 002477887A CA 2477887 A CA2477887 A CA 2477887A CA 2477887 A1 CA2477887 A1 CA 2477887A1
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- Prior art keywords
- rail
- sleeper
- sleepers
- body portion
- track structure
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- 230000003014 reinforcing effect Effects 0.000 claims abstract description 4
- 239000004567 concrete Substances 0.000 claims description 36
- 239000011435 rock Substances 0.000 claims description 15
- 239000011440 grout Substances 0.000 claims description 14
- 238000009424 underpinning Methods 0.000 claims description 14
- 229910000831 Steel Inorganic materials 0.000 claims description 12
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- 230000002787 reinforcement Effects 0.000 claims description 8
- 238000005299 abrasion Methods 0.000 claims description 6
- 229920000642 polymer Polymers 0.000 claims description 6
- 238000011065 in-situ storage Methods 0.000 claims description 5
- 238000009434 installation Methods 0.000 claims description 4
- 239000011150 reinforced concrete Substances 0.000 claims description 4
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 2
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Classifications
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
- E01B3/00—Transverse or longitudinal sleepers; Other means resting directly on the ballastway for supporting rails
- E01B3/28—Transverse or longitudinal sleepers; Other means resting directly on the ballastway for supporting rails made from concrete or from natural or artificial stone
- E01B3/38—Longitudinal sleepers; Longitudinal sleepers integral or combined with tie-rods; Combined longitudinal and transverse sleepers; Layers of concrete supporting both rails
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
- E01B1/00—Ballastway; Other means for supporting the sleepers or the track; Drainage of the ballastway
- E01B1/002—Ballastless track, e.g. concrete slab trackway, or with asphalt layers
- E01B1/004—Ballastless track, e.g. concrete slab trackway, or with asphalt layers with prefabricated elements embedded in fresh concrete or asphalt
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
- E01B1/00—Ballastway; Other means for supporting the sleepers or the track; Drainage of the ballastway
- E01B1/008—Drainage of track
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
- E01B2/00—General structure of permanent way
- E01B2/003—Arrangement of tracks on bridges or in tunnels
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
- E01B2/00—General structure of permanent way
- E01B2/006—Deep foundation of tracks
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
- E01B3/00—Transverse or longitudinal sleepers; Other means resting directly on the ballastway for supporting rails
- E01B3/28—Transverse or longitudinal sleepers; Other means resting directly on the ballastway for supporting rails made from concrete or from natural or artificial stone
- E01B3/32—Transverse or longitudinal sleepers; Other means resting directly on the ballastway for supporting rails made from concrete or from natural or artificial stone with armouring or reinforcement
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
- E01B3/00—Transverse or longitudinal sleepers; Other means resting directly on the ballastway for supporting rails
- E01B3/28—Transverse or longitudinal sleepers; Other means resting directly on the ballastway for supporting rails made from concrete or from natural or artificial stone
- E01B3/32—Transverse or longitudinal sleepers; Other means resting directly on the ballastway for supporting rails made from concrete or from natural or artificial stone with armouring or reinforcement
- E01B3/34—Transverse or longitudinal sleepers; Other means resting directly on the ballastway for supporting rails made from concrete or from natural or artificial stone with armouring or reinforcement with pre-tensioned armouring or reinforcement
Landscapes
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Railway Tracks (AREA)
Abstract
According to one aspect of the invention there is provided a prefabricated rail sleeper [10] suitable for use in erecting a track structure [30]. The rail sleeper [10] comprises an elongate body portion [12] for supporting rails [14], the body portion [12] including a top surface [12.1], a bottom face [12.2] and at least two side faces [12.3], and terminating at least at one end thereof in a transition joint formation [16] dimensioned matingly to engage a complimentarily dimensioned transition joint formation [16] of an adjacent rail sleeper [10] in use so as to form a substantially continuous track structure. The sleeper [10] also includes a series of block formations [20], each of which is at least partially outwardly flared and extending beyond the side faces [12.3] of the body portion [12] so as to increase shear interlock of the sleeper [10] with the track bed to reduce longitudinal creep; as well as a series of transverse drainage ducts [26] extending underneath the rail sleeper [10] for allowing rainwater drainage between different side faces [12.3] of the body portion [12] and away from the rail sleeper. The invention extends to a ballast-free track structure [30] comprising at least two rail sleepers [10] according to the invention wherein the sleepers are located in spaced parallel orientation on a ballast-free track bed so as to define a centre drain [32] between the sleepers; and including a mesh [34] located between the sleepers [10] for reinforcing the centre drain [32].
Description
RAIL SLEEPER AND BALLAST-FREE TRACK STRUCTURE
Technical field This invention relates to a ballast-free track structure suitable for carrying railway rails, s and to a rail sleeper for use in such a structure.
Background art Conventional methods for laying a railway track involve placing large wooden, reinforced concrete or steel sleepers on a ballasted track bed, after which rails are io fastened to the sleepers. The purpose of the ballast is to provide a free-draining foundation with high shear strength and good elastic (resilient) properties.
However, for over a century there has been very little fundamental improvement in the design and construction of conventional, ballasted railway track.
Consequently, some is serious and persistent problems have never been completely resolved. In particular, the progressive degradation of the track structure under repeated loading remains problematic. This degradation is manifest in several ways, including loss of geometric stability (the ballast spreads and settles, resulting in loss of vertical and horizontal alignment); loss of resilience (the ballast degrades and becomes contaminated by finer 2o material resulting in increased dynamic damage to track structure (corrugations) as well as to rolling stock); and pumping of sub-grade (caused by dynamic loading, and resulting in ballast fouling and destruction of formation).
The control of these problems is expensive due to heavy ongoing maintenance 2s requirements as well as foreshortened track and rolling stock life spans.
In recent years additional environmental requirements to reduce noise and ground-borne vibrations
Technical field This invention relates to a ballast-free track structure suitable for carrying railway rails, s and to a rail sleeper for use in such a structure.
Background art Conventional methods for laying a railway track involve placing large wooden, reinforced concrete or steel sleepers on a ballasted track bed, after which rails are io fastened to the sleepers. The purpose of the ballast is to provide a free-draining foundation with high shear strength and good elastic (resilient) properties.
However, for over a century there has been very little fundamental improvement in the design and construction of conventional, ballasted railway track.
Consequently, some is serious and persistent problems have never been completely resolved. In particular, the progressive degradation of the track structure under repeated loading remains problematic. This degradation is manifest in several ways, including loss of geometric stability (the ballast spreads and settles, resulting in loss of vertical and horizontal alignment); loss of resilience (the ballast degrades and becomes contaminated by finer 2o material resulting in increased dynamic damage to track structure (corrugations) as well as to rolling stock); and pumping of sub-grade (caused by dynamic loading, and resulting in ballast fouling and destruction of formation).
The control of these problems is expensive due to heavy ongoing maintenance 2s requirements as well as foreshortened track and rolling stock life spans.
In recent years additional environmental requirements to reduce noise and ground-borne vibrations
2 have added impetus to a growing interest in the rail industry to move away from the old ballasted track systems towards more rigid structures, which provide enduring geometric stability and require reduced maintenance.
s Several efforts have been made to develop more rigid track structures, most of which have centred on "sleeper-track" or "slab-track" alternatives. One such system is the Japanese "ladder track" system, in terms of which two longitudinal parallel sleepers are joined to each other by transverse steel or concrete sleepers extending between the longitudinal sleepers and which act as gauge ties, the arrangement being such that the io finished product looks like a ladder laid on the ground. The concrete sleepers are partially pre-stressed in a factory.
A major disadvantage of this system is that it still relies on a ballasted formation and so remains susceptible to the problems described hereinbefore. A further disadvantage Is associated with this system is that it is often characterised by poor load dispersal and weak resistance to longitudinal creep movement of the sleepers.
Yet another method of installing a railway track is by in situ casting of the track sleepers.
This can be done, for example, by preparing longitudinal trenches for the rails and 20 laying flexible tubes in the trenches. The flexible tubes are filled with concrete so that a rail sleeper is formed that is dimensioned for accepting the rails.
Alternatively, the sleepers can be cast on the ground surface by providing lateral restraint to the wet concrete by means of shutters.
2s One of the disadvantages associated with this method is the relatively extensive time involved for construction, maintenance and reconstruction of the track, because of
s Several efforts have been made to develop more rigid track structures, most of which have centred on "sleeper-track" or "slab-track" alternatives. One such system is the Japanese "ladder track" system, in terms of which two longitudinal parallel sleepers are joined to each other by transverse steel or concrete sleepers extending between the longitudinal sleepers and which act as gauge ties, the arrangement being such that the io finished product looks like a ladder laid on the ground. The concrete sleepers are partially pre-stressed in a factory.
A major disadvantage of this system is that it still relies on a ballasted formation and so remains susceptible to the problems described hereinbefore. A further disadvantage Is associated with this system is that it is often characterised by poor load dispersal and weak resistance to longitudinal creep movement of the sleepers.
Yet another method of installing a railway track is by in situ casting of the track sleepers.
This can be done, for example, by preparing longitudinal trenches for the rails and 20 laying flexible tubes in the trenches. The flexible tubes are filled with concrete so that a rail sleeper is formed that is dimensioned for accepting the rails.
Alternatively, the sleepers can be cast on the ground surface by providing lateral restraint to the wet concrete by means of shutters.
2s One of the disadvantages associated with this method is the relatively extensive time involved for construction, maintenance and reconstruction of the track, because of
3 curing times of the concrete. Other disadvantages include the logistics and complexity of construction, and accompanying difficulties associated with site quality assurance and control.
s Obiect of the invention It is an object of the present invention to provide a rail sleeper suitable for use in erecting a railway track that will overcome or at least minimize some of the problems associated with the prior art and which will facilitate rapid installation and replacement of railway tracks.
to It is a further object of the invention to provide a ballast-free track structure and a method for laying the same that will overcome or minimize some of the problems associated with known track structures, or at least will provide a useful alternative to known structures of this nature.
is Disclosure of invention According to the invention there is provided a prefabricated rail sleeper suitable for use in erecting a track structure, the sleeper comprising an elongate body portion for supporting rails, the body portion including a top face, a bottom face and at least two zo side faces, and terminating at least at one end thereof in a transition joint formation dimensioned matingly to engage a complimentarily dimensioned transition joint formation of an adjacent rail sleeper in use so as to form a substantially continuous track structure.
2s The rail sleeper may be located on a ballast-free track bed during erection of the track structure.
s Obiect of the invention It is an object of the present invention to provide a rail sleeper suitable for use in erecting a railway track that will overcome or at least minimize some of the problems associated with the prior art and which will facilitate rapid installation and replacement of railway tracks.
to It is a further object of the invention to provide a ballast-free track structure and a method for laying the same that will overcome or minimize some of the problems associated with known track structures, or at least will provide a useful alternative to known structures of this nature.
is Disclosure of invention According to the invention there is provided a prefabricated rail sleeper suitable for use in erecting a track structure, the sleeper comprising an elongate body portion for supporting rails, the body portion including a top face, a bottom face and at least two zo side faces, and terminating at least at one end thereof in a transition joint formation dimensioned matingly to engage a complimentarily dimensioned transition joint formation of an adjacent rail sleeper in use so as to form a substantially continuous track structure.
2s The rail sleeper may be located on a ballast-free track bed during erection of the track structure.
4 The body portion may terminate at both ends thereof in a transition joint formation, the arrangement being such that when a series of rail sleepers are arranged in end-to-end orientation on a track bed, they together form a substantially continuous track structure s without the need for continuity of reinforcement between adjacent sleepers.
The rail sleepers may be orientated in end-to-end orientation on a ballast-free track bed in such a manner that a transition joint space is defined between the transition joint formations of adjacent sleepers for permitting gradual stress transfer between sleepers and preventing lateral displacement between the same.
io The rail sleeper also may include at least one block formation dimensioned for supporting a rail. In a preferred form of the invention the rail sleeper may include a number of block formations equally spaced along the length of the sleeper such that the bottom surfaces of the block formations are arranged substantially flush with the bottom is face of the body portion. The block formations may be at least partially flared block formations, each block formation including a top surface, a bottom surface and at least two side surfaces. The side surfaces may be characterised therein that they are at least partially outwardly flared from the top surface towards the bottom surface, extending beyond the side faces of the body portion, so as to increase shear interlock of the 2o sleeper with the track bed to reduce longitudinal creep.
The top surfaces of the block formations may be dimensioned for receiving rail fasteners. In particular, the top surfaces of the block formations may be raised relative to the top face of the body portion such that, in use, a gap exists between a rail foot and 2s the top face of the body portion for permitting rail foot drainage, especially when sleepers are backfilled, thus limiting rail-sleeper abrasion and rail-to-rail signaling shorts. The gap also allows free access for welding of rail joints and the passage of under-rail services.
The rail sleeper optionally may include at least one bore arranged proximate the block s formation and extending between the top and bottom faces of the body portion, the bore being dimensioned for receiving grout or the like therein for underpinning the block formation and a rail foot. The bore may be lined with a corrugated polymeric sheath to provide non-brittle shear interlock.
io The rail sleeper further may include at least on drainage duct for facilitating drainage of liquid, such as rainwater, away from the rail sleeper. The drainage duct may be a transverse duct extending underneath the rail sleeper and defined by a box-out recess in the bottom face of the body portion, the arrangement being such that liquid can drain between different side faces of the body portion by running through the bottom is transverse duct. In a preferred form of the invention, the rail sleeper may include a series of transverse ducts that are longitudinally spaced along the length of the sleeper.
The rail sleeper also may include at least one longitudinal service duct located in and extending along the length of the body portion for accommodating, for example, 2o electrical and/or optic fibre cabling.
The rail sleeper further may include ,resilient pads of high performance polymers arranged on the top surface of each block formation and dimensioned for receiving a rail foot thereon such that the resilient pads at least partially protect the rail sleepers from 2s dynamic and impact loads exerted on the sleepers, which could result in brittle or fatigue failure modes.
The rail sleeper may be pre-cast from pre-stressed, post-tensioned or conventionally reinforced concrete. The rail sleepers may be characterised therein that they are pre-cast in an upside down manner to ensure that the top face of the sleeper, to which the rails are attached, consists of the densest concrete.
The concrete may be cured by using steam, water or chemical curing compounds.
The properties of the wet concrete may be modified using additives such as plasticisers, accelerators or retarders, while the properties of set concrete may be modified by epoxy or polymeric impregnation to increase abrasion resistance and enhance chemical io durability.
The reinforcement may be augmented or completely replaced by fibres (fibre reinforced concrete (FRC)) to enhance toughness under repeated loading. The fibres may consist of polymeric, natural or steel fibres (galvanised or epoxy coated steel for aggressive is conditions) to provide increased abrasion resistance, increased ductility and crack resistance, and resistance to impact and dynamic loading.
The concrete in the sleepers may be characterised therein that it incorporates a proportion of sand-sized rubber particles such that the rubber particles reduce the 2o Young's Modulus of the concrete while not compromising strength, rendering the concrete less brittle and thus more resistant to dynamic or impact forces.
The rail sleepers may be formed in several lengths so as to accommodate curves of different radii.
According to another aspect of the invention there is provided a prefabricated rail sleeper suitable for use in erecting a track structure, the sleeper comprising an elongate body portion for supporting rails, the body portion including a top face, a bottom face and at least two side faces; and at least on drainage duct for facilitating drainage of s liquid, such as rainwater, away from the rail sleeper.
The drainage duct may by a transverse duct extending underneath the rail sleeper and defined by a box-out recess in the bottom face of the body portion, the arrangement being such that liquid can drain between different side faces of the body portion by io running through the bottom transverse duct. In a preferred form of the invention, the rail sleeper may include a series of transverse ducts that are longitudinally spaced along the length of the sleeper.
According to yet another aspect of the invention there is provided a prefabricated rail is sleeper suitable for use in erecting a track structure, the sleeper comprising an elongate body portion for supporting rails, the body portion including a top face, a bottom face and at least two side faces; and at least one block formation dimensioned for at least partially accommodating a rail, the block formation being characterised therein that it is at least partially flared.
Preferably, the rail sleeper includes a number of block formations equally spaced along the length of the sleeper such that the bottom surfaces of the block formations are arranged substantially flush with the bottom face of the body portion.
2s Each block formation may include a top surface, a bottom surface and at least two side surfaces. The side surfaces may be characterised therein that they are at least partially outwardly flared from the top surface towards the bottom surface such that the block formations extend beyond the side faces of the body portion so as to increase shear interlock of the sleeper with the track bed.
s The top surfaces of the block formations may be dimensioned for receiving rail fasteners. In particular, the top surfaces of the block formations may be raised relative to the top face of the body portion such that, in use, a gap exists between a rail foot and the top face of the body portion for permitting rail foot drainage when sleepers are backfilled, thus limiting rail-sleeper abrasion and rail-to-rail signaling shorts. The gap to also allows free access for welding of rail joints and the passage of under-rail services.
Each block formation optionally may include at least one bore extending at least partially between the top and bottom surfaces of the block formation and dimensioned for receiving grout or the like therein for underpinning the block formation and a rail foot.
is The bore may be lined with a corrugated polymeric sheath to provide non-brittle shear interlock. A rock dowel or micro pile may be installed through the bore for underpinning the sleeper in poor ground conditions and for fixing sleeper location on steep grades, sharp curves or the like, the rock dowel or micro pile comprising of an elongate bore extending vertically through the rail sleeper and into the ground underneath, the 2o elongate bore being filled with concrete, grout, crushed rock particles or the like.
According to another aspect of the invention there is provided a ballast-free track structure suitable for carrying rails of a railway track, the track structure comprising a series of rail sleepers according to the invention wherein the sleepers are located in zs end-to-end orientation on a ballast-free track bed such that the transition joint formation of one sleeper matingly engages the transition joint formation of an adjacent sleeper, the arrangement being such that they form a substantially continuous track structure without the necessity for continuity of reinforcement between adjacent sleepers.
The transition joint formations may be dimensioned for limiting lateral movement of the s sleepers so as at least partially to limit independent deflection of the sleepers and for reducing bending and shear stresses in a rail. The transition joint between adjacent rail sleepers may be secured by underpinning the joint using in-situ polymeric concrete, installing a jockey slab underneath the joint, or by means of bolted connections for accommodating longitudinal expansion and contraction of adjacent sleepers.
io According to another aspect of the invention there is provided a ballast-free track structure suitable for carrying rails of a railway track wherein the track structure a comprises at least two rail sleepers according to the invention located in spaced parallel orientation on a ballast-free track bed so as to define a centre drain between the is sleepers; and a mesh located between the sleepers for reinforcing the centre drain.
The mesh may be fixed to the body portion of at least one rail sleeper and may extend from a side face thereof. In one form of the invention, the mesh may be fixed to both of the rail sleepers so that the sleepers and mesh-reinforced centre drain form a track Zo slab. The mesh may be weld mesh. Once the rail sleepers are laid on the track bed, successive weld meshes may be laced together for effecting structural continuity of the track slab.
The rail sleepers may be connected to each other by means of at least one cross tie 2s extending between adjacent parallel sleepers. In a preferred form of the invention, the rail sleepers are connected to each other through a series of steel cross ties extending between adjacent parallel sleepers spaced along the length of the track structure.
The track structure also may include one or more resilient mats arranged intermediate s the bottom face of the body portion and the track bed. The resilient mats may comprise of relatively soft polymers adapted at least partially to absorb dynamic or impact loading between the rail sleepers and hard sub-strata such as tunnel floors, concrete bridges and the like, and to attenuate structure-borne or ground-borne noise and vibration.
io The track structure also may comprise at least one rock dowel or micro pile located underneath the rail sleeper and proximate a block formation for underpinning the sleeper in poor ground conditions and for fixing sleeper location on steep grades, sharp curves or the like, the rock dowel or micro pile comprising of an elongate bore extending vertically through the rail sleeper and into the ground, the elongate bore being filled with is concrete, grout, crushed rock particles or the like.
The track structure, may be adapted to accommodate slow and high-speed installations, and may range from light axle load applications, such as mine tracks (in the order of 10 tonne axle load), to heavy haul applications in surface track (in excess of 35 tonne axle load).
According to yet a further aspect of the invention there is provided a method of laying a ballast-free track structure which is suitable for carrying rails of a railway track, the method comprising the steps of constructing a base formation (earthworks) layer works zs to a specified strength and dimensional tolerances; fixing rail sleepers according to the invention in spaced parallel orientation to form track panels; laying the fixed track panels in end-to-end orientation on the pre-prepared ballast-free formation layer works;
placing and fastening rails into position on the rail sleepers; and mechanically adjusting vertical and horizontal alignment of the rail sleepers.
s Vertical alignment may be achieved by lifting (jacking) and wedging the track panels to the correct height and packing dry-mix concrete or crusher run underneath the sleepers.
Alternatively, where setting times allow, vertical alignment may be achieved by appropriate grout injections or by inserting grout packs. Horizontal alignment may be achieved by dragging the sleeper laterally. Re-alignment of previously installed track io may be achieved by exposing the base of the sleeper and tamping in additional dry mix or other material.
The sleepers may be pre-cast upside down in specially designed steel shutters to ensure that the top face of the sleeper, to which the rails are attached, consists of the is densest concrete. The concrete is placed into steel shutters and vibrated to ensure maximum density.
Specific embodiment of the invention Without limiting the scope thereof, two embodiments of the invention will now be 2o described by way of example only and with reference to the accompanying drawing wherein -Figure 1 is an isometric view of a rail sleeper according to one embodiment of the invention, wherein the rail sleeper is designed for light axle load 2s applications such as underground mining;
Figure 2 is an isometric view of a rail sleeper according to another embodiment of the invention, wherein the rail sleeper is designed for heavier axle loads such as main line applications;
Figure 3 is an isometric view of a track structure according to one embodiment of s the invention;
Figure 4 is an isometric view of a track structure according to another embodiment of the invention, including a wire mesh extending between the sleepers;
Figure 5 is a transverse cross-sectional view of the track structure of Figure 4;
Figure 6 is a transverse cross-sectional view of a track structure according to the io invention illustrating a possible configuration of a centre drain and underpinning of the rail sleeper;
Figure 7 is a plan view of the track structure of Figure 4.
A rail sleeper according to the invention there is generally designated by reference is numeral 10. The rail sleeper 10 comprises an elongate body portion 12 for supporting rails 14. The body portion 12 includes a top face 12.1, a bottom face 12.2 and at least two side faces 12.3.
The body portion 12 terminates at least at one end thereof in a transition joint formation 20 16 that is dimensioned for matingly engaging a complimentarily dimensioned transition joint formation 16 of an adjacent rail sleeper 10 in use. The arrangement is such that the connection between the sleepers 10 forms a substantially continuous track structure 30.
Zs In a preferred form of the invention, the body portion 12 terminates at both ends thereof in a transition joint formation 16, the arrangement being such that when a series of rail sleepers 10 are arranged in end-to-end orientation on the track bed, they together form a substantially continuous track structure 30 without the need for continuity of reinforcement between adjacent sleepers 10. The rail sleepers 10 are orientated in end-to-end orientation on a ballast-free track bed in such a manner that a transition joint s space 18 (Figure 7) is defined between the transition joint formations 16 of adjacent sleepers 10 in a manner permitting gradual stress transfer between the sleepers 10 and limiting independent movement of the sleepers 10 so as at least partially to limit independent deflection of the rail sleepers 10 and for reducing bending and shear stresses in a rail 14.
io The rail sleeper 10 also includes at least two spaced block formations 20 for supporting the rails 14. Each block formation 20 includes a top surface 20.1, a bottom surface 20.2 and at least two side surfaces 20.3. The block formations 20 are at least partially flared block formations 20. More particularly, the side surfaces 20.3 are characterised therein is that they are at least partially outwardly flared from the top surface 20.1 towards the bottom surface 20.2, extending beyond the side faces 12.3 of the body portion 12, so as to increase shear interlock of the sleeper 10 with the track bed. The rail sleeper 10 preferably includes a number of block formations 20 that are substantially equally spaced along the length of the sleeper 10 such that the bottom surfaces 20.2 of the 2o block formations 20 are arranged substantially flush with the bottom face 12.2 of the body portion 12.
The top surfaces 20.1 of the block formations 20 are dimensioned for receiving rail fasteners 37 for the rails 14. In particular, the top surfaces 20.1 of the block formations zs 20 are raised relative to the top face 12.1 of the body portion 12 such that, in use, a gap exists between a rail foot and the top face 12.1 of the body portion 12 for permitting rail foot drainage when the sleepers 10 are backfilled, such as in surface track applications, thus limiting rail-sleeper abrasion and rail-to-rail signaling shorts.
A block formation 20 optionally also includes at least one bore 22 (Figures 6 and 7) s extending at least partially between the top and bottom. surfaces 20.1, 20.2 of the block formation 20. The bore 22 is lined with a corrugated polymeric sheath (not shown) to provide non-brittle shear interlock. The bore 22 is dimensioned for receiving grout or the like therein for underpinning the rail sleeper 10.
io The rail sleeper 10 further includes at least on drainage duct 26 for facilitating drainage of liquid, such as rainwater, away from the rail sleeper 10. The drainage duct is a transverse duct 26 extending underneath the rail sleeper 10 and defined by a box-out recess in the bottom face 12.2 of the body portion 12, the arrangement being such that liquid can drain between different side faces 12.3 of the body portion 12 by running is through the bottom transverse duct 26. In a preferred form of the invention, the rail sleeper 10 includes a series of transverse ducts 26 that are longitudinally spaced along the length of the sleeper 10.
The rail sleeper 10 also includes at least one longitudinal service duct 24 located in and zo extending along the length of the body portion 12 for accommodating, for example, electrical and/or optic fibre cabling.
The rail sleeper 10 also includes resilient pads 36 (Figure 5) of high performance polymers arranged on the top surtace 20.1 of each block formation 20 and dimensioned Zs for receiving a rail foot thereon such that the resilient pads 36 at least partially protect the rail sleepers 10 from dynamic and impact loads exerted on the sleepers 10, which could result in brittle or fatigue failure modes.
The rail sleeper 10 is generally pre-cast from pre-stressed, post-tensioned or s conventionally reinforced concrete.
The invention also provides for a ballast-free track structure 30 suitable for carrying rails 14 of a railway track. The track structure 30 comprises a series of rail sleepers 10 according to the invention wherein the sleepers 10 are located in end-to-end orientation to on a ballast-free track bed such that the transition joint formation 16 of one sleeper 10 matingly engages the transition joint formation 16 of an adjacent sleeper 10.
The arrangement is such that they form a substantially continuous track structure 30 without continuity of reinforcement between adjacent sleepers 10.
is The transition joint formations 16 are dimensioned for limiting lateral movement of the sleepers 10 so as at least partially to limit independent deflection of the sleepers 10 and for reducing bending and shear stresses in a rail 14. The transition joint between adjacent track sleepers 10 are secured by underpinning the joint using in situ polymeric concrete, installing a jockey slab underneath the joint, or by means of bolted 2o connections for accommodating longitudinal expansion and contraction of adjacent sleepers.
The track structure 30 further includes a second row of track sleepers 10 that are located in spaced parallel orientation from the first row of track sleepers 10 on a ballast-2s free track bed. The rail sleepers 10 are held at the correct spacing by means of steel or concrete cross ties 60 fixed to or cast into a rail sleeper 10 on either side.
An optional feature is to place in-situ concrete 42 (Figure 6) between the rail sleepers so as to define a centre drain 32 between the sleepers. Where the centre drain option is exercised, a preferred option is to fix a reinforcing mesh 34 between the rail sleepers 10 to reinforce the centre drain 32 and effectively form a track slab. Once the s rail sleepers 10 are laid on the track bed, successive weld meshes 34 are laced together to form structural continuity between the sleepers 10.
The track structure 30 also includes one or more resilient mats 38 (Figure 5) arranged intermediate the bottom face 12.2 of the body portion 12 and the track bed.
The to resilient mats 38 comprise of relatively soft polymers that are adapted at least partially to absorb dynamic or impact loading between the rail sleepers 10 and hard sub-strata such as tunnel floors, concrete bridges and the like, and to attenuate structure-borne or ground-borne noise and vibration.
is The track structure 30 also comprises at least one rock dowel or micro pile 40 (Figure 6) located under a block formation 20 of the rail sleeper 10 for underpinning the sleeper 20 in poor ground conditions and for fixing the steeper location on steep grades, sharp curves or the like. The rock dowel or micro pile 40 is installed through the bore 22 and comprises of an elongate bore extending vertically through the rail sleeper 10 and into 2o the ground underneath a block formation 20, the elongate bore 40 being filled with concrete, grout, crushed rock particles or the like.
The track structure 30 is adapted to accommodate slow and high-speed installations, and range from light axle load applications, such as mine tracks (in the order of 10 2s tonne axle load in), to heavy haul applications in surface track (in excess of 35 tonne axle load).
It will be appreciated that various other embodiments of the invention may be possible without departing from the spirit or scope of the invention as defined in the claims.
The rail sleepers may be orientated in end-to-end orientation on a ballast-free track bed in such a manner that a transition joint space is defined between the transition joint formations of adjacent sleepers for permitting gradual stress transfer between sleepers and preventing lateral displacement between the same.
io The rail sleeper also may include at least one block formation dimensioned for supporting a rail. In a preferred form of the invention the rail sleeper may include a number of block formations equally spaced along the length of the sleeper such that the bottom surfaces of the block formations are arranged substantially flush with the bottom is face of the body portion. The block formations may be at least partially flared block formations, each block formation including a top surface, a bottom surface and at least two side surfaces. The side surfaces may be characterised therein that they are at least partially outwardly flared from the top surface towards the bottom surface, extending beyond the side faces of the body portion, so as to increase shear interlock of the 2o sleeper with the track bed to reduce longitudinal creep.
The top surfaces of the block formations may be dimensioned for receiving rail fasteners. In particular, the top surfaces of the block formations may be raised relative to the top face of the body portion such that, in use, a gap exists between a rail foot and 2s the top face of the body portion for permitting rail foot drainage, especially when sleepers are backfilled, thus limiting rail-sleeper abrasion and rail-to-rail signaling shorts. The gap also allows free access for welding of rail joints and the passage of under-rail services.
The rail sleeper optionally may include at least one bore arranged proximate the block s formation and extending between the top and bottom faces of the body portion, the bore being dimensioned for receiving grout or the like therein for underpinning the block formation and a rail foot. The bore may be lined with a corrugated polymeric sheath to provide non-brittle shear interlock.
io The rail sleeper further may include at least on drainage duct for facilitating drainage of liquid, such as rainwater, away from the rail sleeper. The drainage duct may be a transverse duct extending underneath the rail sleeper and defined by a box-out recess in the bottom face of the body portion, the arrangement being such that liquid can drain between different side faces of the body portion by running through the bottom is transverse duct. In a preferred form of the invention, the rail sleeper may include a series of transverse ducts that are longitudinally spaced along the length of the sleeper.
The rail sleeper also may include at least one longitudinal service duct located in and extending along the length of the body portion for accommodating, for example, 2o electrical and/or optic fibre cabling.
The rail sleeper further may include ,resilient pads of high performance polymers arranged on the top surface of each block formation and dimensioned for receiving a rail foot thereon such that the resilient pads at least partially protect the rail sleepers from 2s dynamic and impact loads exerted on the sleepers, which could result in brittle or fatigue failure modes.
The rail sleeper may be pre-cast from pre-stressed, post-tensioned or conventionally reinforced concrete. The rail sleepers may be characterised therein that they are pre-cast in an upside down manner to ensure that the top face of the sleeper, to which the rails are attached, consists of the densest concrete.
The concrete may be cured by using steam, water or chemical curing compounds.
The properties of the wet concrete may be modified using additives such as plasticisers, accelerators or retarders, while the properties of set concrete may be modified by epoxy or polymeric impregnation to increase abrasion resistance and enhance chemical io durability.
The reinforcement may be augmented or completely replaced by fibres (fibre reinforced concrete (FRC)) to enhance toughness under repeated loading. The fibres may consist of polymeric, natural or steel fibres (galvanised or epoxy coated steel for aggressive is conditions) to provide increased abrasion resistance, increased ductility and crack resistance, and resistance to impact and dynamic loading.
The concrete in the sleepers may be characterised therein that it incorporates a proportion of sand-sized rubber particles such that the rubber particles reduce the 2o Young's Modulus of the concrete while not compromising strength, rendering the concrete less brittle and thus more resistant to dynamic or impact forces.
The rail sleepers may be formed in several lengths so as to accommodate curves of different radii.
According to another aspect of the invention there is provided a prefabricated rail sleeper suitable for use in erecting a track structure, the sleeper comprising an elongate body portion for supporting rails, the body portion including a top face, a bottom face and at least two side faces; and at least on drainage duct for facilitating drainage of s liquid, such as rainwater, away from the rail sleeper.
The drainage duct may by a transverse duct extending underneath the rail sleeper and defined by a box-out recess in the bottom face of the body portion, the arrangement being such that liquid can drain between different side faces of the body portion by io running through the bottom transverse duct. In a preferred form of the invention, the rail sleeper may include a series of transverse ducts that are longitudinally spaced along the length of the sleeper.
According to yet another aspect of the invention there is provided a prefabricated rail is sleeper suitable for use in erecting a track structure, the sleeper comprising an elongate body portion for supporting rails, the body portion including a top face, a bottom face and at least two side faces; and at least one block formation dimensioned for at least partially accommodating a rail, the block formation being characterised therein that it is at least partially flared.
Preferably, the rail sleeper includes a number of block formations equally spaced along the length of the sleeper such that the bottom surfaces of the block formations are arranged substantially flush with the bottom face of the body portion.
2s Each block formation may include a top surface, a bottom surface and at least two side surfaces. The side surfaces may be characterised therein that they are at least partially outwardly flared from the top surface towards the bottom surface such that the block formations extend beyond the side faces of the body portion so as to increase shear interlock of the sleeper with the track bed.
s The top surfaces of the block formations may be dimensioned for receiving rail fasteners. In particular, the top surfaces of the block formations may be raised relative to the top face of the body portion such that, in use, a gap exists between a rail foot and the top face of the body portion for permitting rail foot drainage when sleepers are backfilled, thus limiting rail-sleeper abrasion and rail-to-rail signaling shorts. The gap to also allows free access for welding of rail joints and the passage of under-rail services.
Each block formation optionally may include at least one bore extending at least partially between the top and bottom surfaces of the block formation and dimensioned for receiving grout or the like therein for underpinning the block formation and a rail foot.
is The bore may be lined with a corrugated polymeric sheath to provide non-brittle shear interlock. A rock dowel or micro pile may be installed through the bore for underpinning the sleeper in poor ground conditions and for fixing sleeper location on steep grades, sharp curves or the like, the rock dowel or micro pile comprising of an elongate bore extending vertically through the rail sleeper and into the ground underneath, the 2o elongate bore being filled with concrete, grout, crushed rock particles or the like.
According to another aspect of the invention there is provided a ballast-free track structure suitable for carrying rails of a railway track, the track structure comprising a series of rail sleepers according to the invention wherein the sleepers are located in zs end-to-end orientation on a ballast-free track bed such that the transition joint formation of one sleeper matingly engages the transition joint formation of an adjacent sleeper, the arrangement being such that they form a substantially continuous track structure without the necessity for continuity of reinforcement between adjacent sleepers.
The transition joint formations may be dimensioned for limiting lateral movement of the s sleepers so as at least partially to limit independent deflection of the sleepers and for reducing bending and shear stresses in a rail. The transition joint between adjacent rail sleepers may be secured by underpinning the joint using in-situ polymeric concrete, installing a jockey slab underneath the joint, or by means of bolted connections for accommodating longitudinal expansion and contraction of adjacent sleepers.
io According to another aspect of the invention there is provided a ballast-free track structure suitable for carrying rails of a railway track wherein the track structure a comprises at least two rail sleepers according to the invention located in spaced parallel orientation on a ballast-free track bed so as to define a centre drain between the is sleepers; and a mesh located between the sleepers for reinforcing the centre drain.
The mesh may be fixed to the body portion of at least one rail sleeper and may extend from a side face thereof. In one form of the invention, the mesh may be fixed to both of the rail sleepers so that the sleepers and mesh-reinforced centre drain form a track Zo slab. The mesh may be weld mesh. Once the rail sleepers are laid on the track bed, successive weld meshes may be laced together for effecting structural continuity of the track slab.
The rail sleepers may be connected to each other by means of at least one cross tie 2s extending between adjacent parallel sleepers. In a preferred form of the invention, the rail sleepers are connected to each other through a series of steel cross ties extending between adjacent parallel sleepers spaced along the length of the track structure.
The track structure also may include one or more resilient mats arranged intermediate s the bottom face of the body portion and the track bed. The resilient mats may comprise of relatively soft polymers adapted at least partially to absorb dynamic or impact loading between the rail sleepers and hard sub-strata such as tunnel floors, concrete bridges and the like, and to attenuate structure-borne or ground-borne noise and vibration.
io The track structure also may comprise at least one rock dowel or micro pile located underneath the rail sleeper and proximate a block formation for underpinning the sleeper in poor ground conditions and for fixing sleeper location on steep grades, sharp curves or the like, the rock dowel or micro pile comprising of an elongate bore extending vertically through the rail sleeper and into the ground, the elongate bore being filled with is concrete, grout, crushed rock particles or the like.
The track structure, may be adapted to accommodate slow and high-speed installations, and may range from light axle load applications, such as mine tracks (in the order of 10 tonne axle load), to heavy haul applications in surface track (in excess of 35 tonne axle load).
According to yet a further aspect of the invention there is provided a method of laying a ballast-free track structure which is suitable for carrying rails of a railway track, the method comprising the steps of constructing a base formation (earthworks) layer works zs to a specified strength and dimensional tolerances; fixing rail sleepers according to the invention in spaced parallel orientation to form track panels; laying the fixed track panels in end-to-end orientation on the pre-prepared ballast-free formation layer works;
placing and fastening rails into position on the rail sleepers; and mechanically adjusting vertical and horizontal alignment of the rail sleepers.
s Vertical alignment may be achieved by lifting (jacking) and wedging the track panels to the correct height and packing dry-mix concrete or crusher run underneath the sleepers.
Alternatively, where setting times allow, vertical alignment may be achieved by appropriate grout injections or by inserting grout packs. Horizontal alignment may be achieved by dragging the sleeper laterally. Re-alignment of previously installed track io may be achieved by exposing the base of the sleeper and tamping in additional dry mix or other material.
The sleepers may be pre-cast upside down in specially designed steel shutters to ensure that the top face of the sleeper, to which the rails are attached, consists of the is densest concrete. The concrete is placed into steel shutters and vibrated to ensure maximum density.
Specific embodiment of the invention Without limiting the scope thereof, two embodiments of the invention will now be 2o described by way of example only and with reference to the accompanying drawing wherein -Figure 1 is an isometric view of a rail sleeper according to one embodiment of the invention, wherein the rail sleeper is designed for light axle load 2s applications such as underground mining;
Figure 2 is an isometric view of a rail sleeper according to another embodiment of the invention, wherein the rail sleeper is designed for heavier axle loads such as main line applications;
Figure 3 is an isometric view of a track structure according to one embodiment of s the invention;
Figure 4 is an isometric view of a track structure according to another embodiment of the invention, including a wire mesh extending between the sleepers;
Figure 5 is a transverse cross-sectional view of the track structure of Figure 4;
Figure 6 is a transverse cross-sectional view of a track structure according to the io invention illustrating a possible configuration of a centre drain and underpinning of the rail sleeper;
Figure 7 is a plan view of the track structure of Figure 4.
A rail sleeper according to the invention there is generally designated by reference is numeral 10. The rail sleeper 10 comprises an elongate body portion 12 for supporting rails 14. The body portion 12 includes a top face 12.1, a bottom face 12.2 and at least two side faces 12.3.
The body portion 12 terminates at least at one end thereof in a transition joint formation 20 16 that is dimensioned for matingly engaging a complimentarily dimensioned transition joint formation 16 of an adjacent rail sleeper 10 in use. The arrangement is such that the connection between the sleepers 10 forms a substantially continuous track structure 30.
Zs In a preferred form of the invention, the body portion 12 terminates at both ends thereof in a transition joint formation 16, the arrangement being such that when a series of rail sleepers 10 are arranged in end-to-end orientation on the track bed, they together form a substantially continuous track structure 30 without the need for continuity of reinforcement between adjacent sleepers 10. The rail sleepers 10 are orientated in end-to-end orientation on a ballast-free track bed in such a manner that a transition joint s space 18 (Figure 7) is defined between the transition joint formations 16 of adjacent sleepers 10 in a manner permitting gradual stress transfer between the sleepers 10 and limiting independent movement of the sleepers 10 so as at least partially to limit independent deflection of the rail sleepers 10 and for reducing bending and shear stresses in a rail 14.
io The rail sleeper 10 also includes at least two spaced block formations 20 for supporting the rails 14. Each block formation 20 includes a top surface 20.1, a bottom surface 20.2 and at least two side surfaces 20.3. The block formations 20 are at least partially flared block formations 20. More particularly, the side surfaces 20.3 are characterised therein is that they are at least partially outwardly flared from the top surface 20.1 towards the bottom surface 20.2, extending beyond the side faces 12.3 of the body portion 12, so as to increase shear interlock of the sleeper 10 with the track bed. The rail sleeper 10 preferably includes a number of block formations 20 that are substantially equally spaced along the length of the sleeper 10 such that the bottom surfaces 20.2 of the 2o block formations 20 are arranged substantially flush with the bottom face 12.2 of the body portion 12.
The top surfaces 20.1 of the block formations 20 are dimensioned for receiving rail fasteners 37 for the rails 14. In particular, the top surfaces 20.1 of the block formations zs 20 are raised relative to the top face 12.1 of the body portion 12 such that, in use, a gap exists between a rail foot and the top face 12.1 of the body portion 12 for permitting rail foot drainage when the sleepers 10 are backfilled, such as in surface track applications, thus limiting rail-sleeper abrasion and rail-to-rail signaling shorts.
A block formation 20 optionally also includes at least one bore 22 (Figures 6 and 7) s extending at least partially between the top and bottom. surfaces 20.1, 20.2 of the block formation 20. The bore 22 is lined with a corrugated polymeric sheath (not shown) to provide non-brittle shear interlock. The bore 22 is dimensioned for receiving grout or the like therein for underpinning the rail sleeper 10.
io The rail sleeper 10 further includes at least on drainage duct 26 for facilitating drainage of liquid, such as rainwater, away from the rail sleeper 10. The drainage duct is a transverse duct 26 extending underneath the rail sleeper 10 and defined by a box-out recess in the bottom face 12.2 of the body portion 12, the arrangement being such that liquid can drain between different side faces 12.3 of the body portion 12 by running is through the bottom transverse duct 26. In a preferred form of the invention, the rail sleeper 10 includes a series of transverse ducts 26 that are longitudinally spaced along the length of the sleeper 10.
The rail sleeper 10 also includes at least one longitudinal service duct 24 located in and zo extending along the length of the body portion 12 for accommodating, for example, electrical and/or optic fibre cabling.
The rail sleeper 10 also includes resilient pads 36 (Figure 5) of high performance polymers arranged on the top surtace 20.1 of each block formation 20 and dimensioned Zs for receiving a rail foot thereon such that the resilient pads 36 at least partially protect the rail sleepers 10 from dynamic and impact loads exerted on the sleepers 10, which could result in brittle or fatigue failure modes.
The rail sleeper 10 is generally pre-cast from pre-stressed, post-tensioned or s conventionally reinforced concrete.
The invention also provides for a ballast-free track structure 30 suitable for carrying rails 14 of a railway track. The track structure 30 comprises a series of rail sleepers 10 according to the invention wherein the sleepers 10 are located in end-to-end orientation to on a ballast-free track bed such that the transition joint formation 16 of one sleeper 10 matingly engages the transition joint formation 16 of an adjacent sleeper 10.
The arrangement is such that they form a substantially continuous track structure 30 without continuity of reinforcement between adjacent sleepers 10.
is The transition joint formations 16 are dimensioned for limiting lateral movement of the sleepers 10 so as at least partially to limit independent deflection of the sleepers 10 and for reducing bending and shear stresses in a rail 14. The transition joint between adjacent track sleepers 10 are secured by underpinning the joint using in situ polymeric concrete, installing a jockey slab underneath the joint, or by means of bolted 2o connections for accommodating longitudinal expansion and contraction of adjacent sleepers.
The track structure 30 further includes a second row of track sleepers 10 that are located in spaced parallel orientation from the first row of track sleepers 10 on a ballast-2s free track bed. The rail sleepers 10 are held at the correct spacing by means of steel or concrete cross ties 60 fixed to or cast into a rail sleeper 10 on either side.
An optional feature is to place in-situ concrete 42 (Figure 6) between the rail sleepers so as to define a centre drain 32 between the sleepers. Where the centre drain option is exercised, a preferred option is to fix a reinforcing mesh 34 between the rail sleepers 10 to reinforce the centre drain 32 and effectively form a track slab. Once the s rail sleepers 10 are laid on the track bed, successive weld meshes 34 are laced together to form structural continuity between the sleepers 10.
The track structure 30 also includes one or more resilient mats 38 (Figure 5) arranged intermediate the bottom face 12.2 of the body portion 12 and the track bed.
The to resilient mats 38 comprise of relatively soft polymers that are adapted at least partially to absorb dynamic or impact loading between the rail sleepers 10 and hard sub-strata such as tunnel floors, concrete bridges and the like, and to attenuate structure-borne or ground-borne noise and vibration.
is The track structure 30 also comprises at least one rock dowel or micro pile 40 (Figure 6) located under a block formation 20 of the rail sleeper 10 for underpinning the sleeper 20 in poor ground conditions and for fixing the steeper location on steep grades, sharp curves or the like. The rock dowel or micro pile 40 is installed through the bore 22 and comprises of an elongate bore extending vertically through the rail sleeper 10 and into 2o the ground underneath a block formation 20, the elongate bore 40 being filled with concrete, grout, crushed rock particles or the like.
The track structure 30 is adapted to accommodate slow and high-speed installations, and range from light axle load applications, such as mine tracks (in the order of 10 2s tonne axle load in), to heavy haul applications in surface track (in excess of 35 tonne axle load).
It will be appreciated that various other embodiments of the invention may be possible without departing from the spirit or scope of the invention as defined in the claims.
Claims (42)
1. A prefabricated rail sleeper [10] suitable for use in erecting a track structure [30], the sleeper [10] comprising an elongate body portion [12] for supporting rails [14], the body portion [12] including a top face [12.1], a bottom face [12.2] and at least two side faces [12.3]; and terminating at least at one end thereof in a transition joint formation [16] dimensioned matingly to engage a complimentarily dimensioned transition joint formation [16] of an adjacent rail sleeper [10]
in use so as to form a substantially continuous track structure [30].
in use so as to form a substantially continuous track structure [30].
2. The rail sleeper [10] as claimed in claim 1 characterised therein that the body portion [12] terminates at both ends thereof in a transition joint formation [16], the arrangement being such that when a series of rail sleepers [10] are arranged in end-to-end orientation on a track bed, they together form a substantially continuous track structure [30] without the need for continuity of reinforcement between adjacent sleepers [10].
3. The rail sleeper [10] as claimed in claims 1 and 2 characterised therein that the rail sleepers [10] are orientated in end-to-end orientation on a ballast-free track bed and in such a manner that a transition joint space [18] is defined between the transition joint formations [16] of adjacent sleepers [10] for permitting gradual stress transfer and preventing lateral displacement between the sleepers [10].
4. The rail sleeper [10] as claimed in claim 1 characterised therein that it also includes at least one block formation [20] dimensioned for supporting a rail [14], the block formation [20] being characterised therein that it is an at least partially flared formation including a top surface [20.1], a bottom surface [20.2]
arranged substantially flush with the bottom face [12.2] of the body portion [12], and at least two side surfaces [20.3].
arranged substantially flush with the bottom face [12.2] of the body portion [12], and at least two side surfaces [20.3].
5. The rail sleeper [10] as claimed in claim 4 characterised therein that the side surfaces [20.3] of the block formation [20] are at least partially outwardly flared from the top surface [20.1] towards the bottom surface [20.2], extending beyond the side faces [12.3] of the body portion [12], so as to increase shear interlock of the sleeper [10] with the track bed to reduce longitudinal creep.
6. The rail sleeper [10] as claimed in claim 4 characterised therein that it includes a number of block formations [20] equally spaced along the length of the rail sleeper [10].
7. The rail sleeper [10] as claimed in claim 4 characterised therein that the top surface [20.1] of the block formation [20] is dimensioned for receiving rail fasteners [37], and particularly the top surface [20.1] of the block formation [20] is raised relative to the top face [12.1] of the body portion [12] such that, in use, a gap exists between a rail foot and the top face [12.1] of the body portion [12].
8. The rail sleeper [10] as claimed in claim 1 characterised therein that it includes at least one bore [22], lined with a corrugated polymeric sheath, and arranged proximate the block formation [20], extending between the top and bottom faces of the body portion [12], and dimensioned for receiving grout or the like therein for underpinning the block formation [20] and a rail foot.
9. The rail sleeper [10] as claimed in claim 1 characterised therein that it further includes at least one transverse drainage duct [26] extending underneath the rail sleeper [10] and defined by a box-out recess in the bottom face [12.2] of the body portion [12], the arrangement being such that liquid, such as rainwater, can drain between different side faces [12.3] of the body portion [12] and away from the rail sleeper [10] by running through the bottom transverse drainage duct [26].
10. The rail sleeper [10] as claimed in claim 9 characterised therein that it includes a series of transverse ducts [26] that are longitudinally spaced along the length of the sleeper [10].
11. The rail sleeper [10] as claimed in claim 1 characterised therein that it also includes at least one longitudinal service duct [24] located in and extending along the length of the body portion [12] for accommodating, for example, electrical and/or optic fibre cabling.
12. The rail sleeper [10] as claimed in claim 1 characterised therein that it further includes resilient pads [36] of high performance polymers arranged on the top surface [20.1] of each block formation [20] and dimensioned for receiving a rail foot thereon such that the resilient pads [36] at least partially protect the rail sleepers [10] from dynamic and impact loads exerted thereon.
13. The rail sleeper [10] as claimed in claim 1 characterised therein that it is pre-cast from pre-stressed, post-tensioned or conventionally reinforced concrete and, more particularly, is pre-cast in an upside down manner such that the top face [12.1] of the sleeper [10] consists of the densest concrete.
14. The rail sleeper [10] as claimed in claim 13 characterised therein that the concrete is cured by using steam, water or chemical curing compounds, and further characterised therein that the properties of wet concrete are modified by using additives such as plasticisers, accelerators or retarders, while the properties of set concrete are modified by epoxy or polymeric impregnation to increase abrasion resistance and enhance chemical durability.
15. The rail sleeper [10] as claimed in claim 13 characterised therein that the reinforcement is augmented or even replaced by polymeric, natural or steel fibres so as to form fibre reinforced concrete.
16. The rail sleeper [10] as claimed in claim 13 characterised therein that the concrete incorporates a proportion of sand-sized rubber particles.
17. The rail sleeper [10] as claimed in claim 1 characterised therein that it is located on a ballast-free track bed during erection of a track structure [30].
18. The rail sleeper [10] as claimed in claim 1 characterised therein that it is formed in varying lengths so as to accommodate track curves of different radii.
19. A prefabricated rail sleeper [10] suitable for use in erecting a track structure [30], the sleeper [10] comprising an elongate body portion [12] for supporting rails [14], the body portion [12] including a top face [12.1], a bottom face [12.2] and at least two side faces [12.3]; and at least on drainage duct [26] for facilitating drainage of liquid, such as rainwater, away from the rail sleeper [10].
20. The rail sleeper [10] as claimed in claim 19 characterised therein that the drainage duct [26] is a transverse duct [26] extending underneath the rail sleeper [10] and is defined by a box-out recess in the bottom face [12.2] of the body portion [12], the arrangement being such that liquid can drain between different side faces [12.3] of the body portion [12] by running through the bottom transverse drainage duct [26].
21. A prefabricated rail sleeper [10] suitable for use in erecting a track structure [30], the sleeper [10] comprising an elongate body portion [12] for supporting rails [14], the body portion [12] including a top face [12.1], a bottom face [12.2] and at least two side faces [12.3]; and at least one block formation [20] dimensioned for at least partially accommodating a rail [14], the block formation [20] being characterised therein that it is at least partially flared.
22. The rail sleeper [10] as claimed in claim 21 characterised therein that the block formation [20] includes a top surface [20.1], a bottom surface [20.2] arranged substantially flush with the bottom face [12.2] of the body portion [12], and at least two side surfaces [20.3].
23. The rail sleeper [10] as claimed in claims 21 and 22 characterised therein that the side surfaces [20.3] of the block formation [20] are at least partially outwardly flared from the top surface [20.1] towards the bottom surface, extending beyond the side faces [12.3] of the body portion, so as to increase shear interlock of the sleeper [10] with the track bed to reduce longitudinal creep.
24. The rail sleeper [10] as claimed in claim 21 characterised therein that the top surface [20.1] of the block formation [20] is dimensioned for receiving rail fasteners [37], and particularly the top surface [20.1] of the block formation [20] is raised relative to the top face [12.1] of the body portion [12] such that, in use, a gap exists between a rail foot and the top face [12.1] of the body portion [12].
25. The rail sleeper [10] as claimed in claim 21 characterised therein that it includes at least one bore [22], lined with a corrugated polymeric sheath, and arranged proximate the block formation [20], extending between the top and bottom faces of the body portion [12], and dimensioned for receiving grout or the like therein for underpinning the block formation [20] and a rail foot.
26. The rail sleeper [10] as claimed in claim 21 characterised therein that a rock dowel or micro pile [40] is installed through the bore [22] for underpinning the sleeper [10] in poor ground conditions and for fixing sleeper location on steep grades, sharp curves or the like, the rock dowel or micro pile [40] comprising of an elongate bore [22] extending vertically through the rail sleeper [10] and into the ground underneath, the elongate bore [22] being filled with concrete, grout, crushed rock particles or the like.
27. A ballast-free track structure [30] suitable for carrying rails [14] of a railway track, the track structure [30] comprising a series of rail sleepers [10], which each comprises an elongate body portion [12] for supporting rails, the body portion [12]
including a top face [12.1], a bottom face [12.2] and at least two side faces [12.3], and terminating at least at one end thereof in a transition joint formation [16]
dimensioned matingly to engage a complimentarily dimensioned transition joint formation [16] of an adjacent rail sleeper [10]; the track structure [30]
being characterised therein that the sleepers [10] are located in end-to-end orientation on a ballast-free track bed such that the transition joint formation [16] of one sleeper [10] matingly engages the transition joint formation [16] of an adjacent sleeper [10) such that the rail sleepers [10] together form a substantially continuous track structure [30] without the necessity for continuity of reinforcement between adjacent sleepers [10].
including a top face [12.1], a bottom face [12.2] and at least two side faces [12.3], and terminating at least at one end thereof in a transition joint formation [16]
dimensioned matingly to engage a complimentarily dimensioned transition joint formation [16] of an adjacent rail sleeper [10]; the track structure [30]
being characterised therein that the sleepers [10] are located in end-to-end orientation on a ballast-free track bed such that the transition joint formation [16] of one sleeper [10] matingly engages the transition joint formation [16] of an adjacent sleeper [10) such that the rail sleepers [10] together form a substantially continuous track structure [30] without the necessity for continuity of reinforcement between adjacent sleepers [10].
28. The ballast-free track structure [30] as claimed in claim 27 characterised therein that the transition joint formation [16] between adjacent rail sleepers [10]
are secured by underpinning the joint [16] using in-situ polymeric concrete, installing a jockey slab underneath the joint, or by means of bolted connections for accommodating longitudinal expansion and contraction of adjacent sleepers [10].
are secured by underpinning the joint [16] using in-situ polymeric concrete, installing a jockey slab underneath the joint, or by means of bolted connections for accommodating longitudinal expansion and contraction of adjacent sleepers [10].
29. A ballast-free track structure [30] suitable for carrying rails [14] of a railway track wherein the track structure [30] comprises at least two rail sleepers [10], each of which comprises an elongate body portion [12] for supporting rails, the body portion [12] including a top face [12.1], a bottom face [12.2] and at least two side faces [12.3]; wherein the sleepers [10) are located in spaced parallel orientation on a ballast-free track bed so as to define a centre drain [32) between the sleepers; and a mesh [34] located between the sleepers [10] for reinforcing the centre drain [32].
30. The ballast-free track structure [30] as claimed in claim 29 characterised therein that the mesh [34] is fixed to the body portion [12] of at least one rail sleeper [10) and extend from a side face [12.3] thereof, and preferably characterised therein that the mesh [34] is fixed to both of the rail sleepers [10] so that the sleepers and mesh-reinforced centre drain [32] form a track slab.
31. The ballast-free track structure [30] as claimed in claim 29 characterised therein that the mesh [34] is weld mesh which are laced together once the rail sleepers [10] are laid on the track bed for effecting structural continuity of the track slab.
32. The ballast-free track structure [30] as claimed in claim 29 characterised therein that the rail sleepers [10] are connected to each other by means of at least one cross tie [60] extending between adjacent parallel sleepers, and preferably characterised therein that the rail sleepers [10] are connected to each other through a series of steel cross ties [60] extending between adjacent parallel sleepers spaced along the length of the track structure.
33. The ballast-free track structure [30] as claimed in claim 29 characterised therein that the track structure [30] includes one or more resilient mats [38]
arranged intermediate the bottom face [12.2] of the body portion [12] and the track bed, each resilient mat [38] comprising of relatively soft polymers adapted at least partially to absorb dynamic or impact loading between the rail sleepers [10]
and hard sub-strata such as tunnel floors, concrete bridges and the like.
arranged intermediate the bottom face [12.2] of the body portion [12] and the track bed, each resilient mat [38] comprising of relatively soft polymers adapted at least partially to absorb dynamic or impact loading between the rail sleepers [10]
and hard sub-strata such as tunnel floors, concrete bridges and the like.
34. The ballast-free track structure [30] as claimed in claim 29 characterised therein that the track structure [30] also comprises at least one rock dowel or micro pile [40] located underneath the rail sleeper [10) for underpinning the sleeper [10] in poor ground conditions and for fixing sleeper location on steep grades, sharp curves or the like, the rock dowel or micro pile [40] comprising of an elongate bore [22] extending vertically through the rail sleeper [10] and into the ground, the elongate bore [22] being filled with concrete, grout, crushed rock particles or the like.
35. The ballast-free track structure [30] as claimed in claim 29 characterised therein that the track structure [30] is adapted to accommodate slow and high-speed installations, and ranges from light axle load applications, such as mine tracks (in the order of 10 tonne axle load), to heavy haul applications in surface track (in excess of 35 tonne axle load).
36. A method of laying a ballast-free track structure [30] which is suitable for carrying rails [14] of a railway track, the method comprising the steps of constructing a base formation (earthworks) layer works to a specified strength and dimensional tolerances; fixing rail sleepers [10] according to the invention in spaced parallel orientation to form track panels; laying the fixed track panels in end-to-end orientation on the pre-prepared ballast-free formation layer works; placing and fastening rails [14] into position on the rail sleepers [10]; and mechanically adjusting vertical and horizontal alignment of the rail sleepers [10].
37. The method as claimed in claim 36 characterised therein that vertical alignment is achieved by lifting (jacking) and wedging the track panels to the correct height and packing dry-mix concrete or crusher run underneath the sleepers [10], alternatively by appropriate grout injections or by inserting grout packs.
38. The method as claimed in claim 36 characterised therein that horizontal alignment is achieved by dragging the sleeper [10] laterally.
39. A method of manufacturing a concrete rail sleeper [10] comprising an elongate body portion [12] for supporting rails [14], the body portion [12] including a top face [12.1], a bottom face [12.2] and at least two side faces [12.3], the method comprising the steps of pre-casting the sleepers [10] into steel shutters in an upside down fashion so as to ensure that the top face [12.1] of the sleeper [10], to which the rails [14] are attached, consists of the densest concrete; and vibrating the steel shutters to ensure maximum density in the top face [12.1].
40. A prefabricated rail sleeper [10] substantially as herein illustrated and exemplified with reference to the accompanying drawings.
41. A ballast-free track structure [30] suitable for carrying rails [14] of a railway track substantially as herein illustrated and exemplified with reference to the accompanying drawings.
42. A method of laying a ballast-free track structure [30] suitable for carrying rails [14]
of a railway track substantially as herein illustrated and exemplified with reference to the accompanying drawings.
of a railway track substantially as herein illustrated and exemplified with reference to the accompanying drawings.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA2002/1735 | 2002-03-01 | ||
| ZA200201735 | 2002-03-01 | ||
| PCT/ZA2003/000010 WO2003074790A1 (en) | 2002-03-01 | 2003-01-21 | Rail sleeper and ballast-free track structure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2477887A1 true CA2477887A1 (en) | 2003-09-12 |
Family
ID=27789540
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002477887A Abandoned CA2477887A1 (en) | 2002-03-01 | 2003-01-21 | Rail sleeper and ballast-free track structure |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US20050252985A1 (en) |
| CN (1) | CN1646771A (en) |
| AP (1) | AP2004003128A0 (en) |
| AU (1) | AU2003202292A1 (en) |
| BR (1) | BR0303344A (en) |
| CA (1) | CA2477887A1 (en) |
| RU (1) | RU2004129299A (en) |
| WO (1) | WO2003074790A1 (en) |
| ZA (1) | ZA200406976B (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100213267A1 (en) * | 2007-09-25 | 2010-08-26 | Msb-Management Gmbh | Rail sleeper |
| HK1134632A2 (en) * | 2008-10-28 | 2010-04-30 | Italian Thai Dev Public Co | Precast track plinth |
| CN102021865B (en) * | 2009-09-23 | 2015-07-08 | 塞斯特拉公司 | Method for precasting rail support tie on precast span piece |
| US8544763B2 (en) * | 2010-03-15 | 2013-10-01 | Concrete Systems Inc. | Prefabricated plinth for supporting a railway track |
| ES2425288B1 (en) * | 2011-05-26 | 2014-06-12 | Andaluza De Traviesas S.A. | PREFABRICATED CONCRETE MODULE FOR RAILWAY TRAINING |
| ES2419554B1 (en) * | 2012-02-17 | 2014-03-20 | Administrador De Infraestructuras Ferroviarias (Adif) | Naughty Rail Aerodynamics |
| MX2014008112A (en) | 2014-07-01 | 2016-01-01 | Bienracon S De Rl De Cv | Ultra resistant monolithic railroad ties made of reinforced concrete in an integral manner with optimum geometry for track balast in reailroads. |
| ES2704178B2 (en) * | 2017-09-14 | 2019-10-23 | Railtech Sufetra S A | Concrete plinth for railway tracks, railway track incorporating said plinths and method of track installation |
| CN110409226B (en) * | 2019-07-25 | 2024-08-27 | 中国铁道科学研究院集团有限公司铁道建筑研究所 | Sleeper bearing |
| SE545224C2 (en) * | 2021-01-27 | 2023-05-30 | Cito Trading Co Bengt Boenstroem | A SELF-SUPPORTING COMPOSITE RAIL, BELOW THE DEVICE |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB143177A (en) * | 1916-04-28 | 1921-05-26 | Charles Rabut | A process of securing longitudinal sleepers or blocks of wood carrying rails on transverse sleepers and other structures of wood, metal, concrete or masonry |
| FR1146446A (en) * | 1956-04-05 | 1957-11-12 | Rail supports for railway tracks | |
| US3300140A (en) * | 1965-12-07 | 1967-01-24 | Railroad Permanent Way Product | Beams for railroad track structure |
| JP2933420B2 (en) * | 1991-08-22 | 1999-08-16 | 積水化学工業株式会社 | How to connect synthetic sleepers |
| JP4224183B2 (en) * | 2000-02-10 | 2009-02-12 | 積水化学工業株式会社 | Synthetic sleeper connection structure and connection method |
-
2003
- 2003-01-21 BR BR0303344-9A patent/BR0303344A/en not_active IP Right Cessation
- 2003-01-21 CN CNA038082578A patent/CN1646771A/en active Pending
- 2003-01-21 US US10/506,132 patent/US20050252985A1/en not_active Abandoned
- 2003-01-21 AP APAP/P/2004/003128A patent/AP2004003128A0/en unknown
- 2003-01-21 CA CA002477887A patent/CA2477887A1/en not_active Abandoned
- 2003-01-21 WO PCT/ZA2003/000010 patent/WO2003074790A1/en not_active Application Discontinuation
- 2003-01-21 RU RU2004129299/11A patent/RU2004129299A/en not_active Application Discontinuation
- 2003-01-21 AU AU2003202292A patent/AU2003202292A1/en not_active Abandoned
-
2004
- 2004-09-01 ZA ZA200406976A patent/ZA200406976B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| CN1646771A (en) | 2005-07-27 |
| BR0303344A (en) | 2004-08-10 |
| AU2003202292A1 (en) | 2003-09-16 |
| RU2004129299A (en) | 2005-05-27 |
| ZA200406976B (en) | 2005-09-12 |
| AP2004003128A0 (en) | 2004-09-30 |
| US20050252985A1 (en) | 2005-11-17 |
| WO2003074790A1 (en) | 2003-09-12 |
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| Date | Code | Title | Description |
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| FZDE | Discontinued |