slab track
TRANSCRIPT
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CONTENTS
DEFINATION Components of slab track Types of slab track Advantages Conclusion
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DEFINITION
SLAB TRACK IS DEFINED AS A TYPE OF TRACK WHERE THE SLEEPERS AND BALLAST ARE REPLACED BY A CONCRETE OR ASHPHALT LAYER.
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HISTORY OF SLAB TRACK
In the late 20th Century slab track started to appear, especially in tunnels, where the floor of the tunnel would be a single slab of concrete in two layers, with the rail attached to fixtures in the second layer. The first layer would seal the floor from water, and attain a profile of approximately the right dimensions. The second layer would be laid to a greater degree of precision.
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Problems in ballast track
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Problems in ballast track
Slow deterioration of the ballast material due to traffic loading
wear & tear of ballast causes geometrical unevenness & clogging leads to drainage problems
Frequent maintenance of track alignment is needed
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Problems in ballast track
Wear and tear creep of rail
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Need of slab track
Very low dynamic stiffness
Reduces vibration and noise significantly
All components are easily replaced
Longitudinal creep resistance can be adjusted
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comparison
Slab trackLess noiseFor high speed railsLonger service lifeLess maintenance
Ballast trackMore noiseFor low speed railsLesser service lifeHeavy maintenance
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Components of slab track
Base plate assembly
Cast in shoulder assembly
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COMPONENTS OF SLAB TRACK
Rubber wedges which support the rail at the web Side support brackets which hold these in place and transfer load to the support structure locking wedges, which fix the side bracketsShoulders which provide location and the reaction point against which the fastening is braced
FUNCTIONS
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CONSTRUCTION OF SLAB TRACK
Subgrade soil: PI =5.9
LL = 18.5
moisture content =5 to 12 %
OMC = 10.5%
The modulus of the soil is > 10,000 psi Compressive strength
> 50 psi.
Figure :The final prepared sub grade surface. 14
Subbase
The subbase is a 6-inch soil cement layer (5%)
Compacted at an optimum moisture content of 12.5%
Compaction is specified to be 98 percent
The target compressive strength is 700 psi
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Fig : sub base with soil cement layer Fig: Compaction of sub base with soil cement layer
Fig : sub base with soil cement layer Fig: Compaction of sub base with soil cement layer
Fig: Final surface of the soil cement layer.
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METHODS OF LAYING SLAB TRACK
Two methods
1.Direction Fixation Slab Track (DFST)
2.Independent Dual Block Track (IDBT)
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Direction Fixation Slab Track (DFST) Slab is 1 foot thick
10 feet 6 inches wide & 5,000 psi
Track resilience and damping are provided primarily through the rubber pads installed between the fastener plates and the slab surface.
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Independent Dual Block Track
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Independent Dual Block TrackSlab is 7.75-inch-thick reinforced bottom
concrete slab
10 feet 6 inches wide and 5,000 psi
Track resilience and damping were provided
primarily through the rubber boots as well as the pads installed inside rubber boots.
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conclusion Concrete slab track is constructed
particularly for high-speed rails Soil pressures are evenly distributed under slab track Slab track can maintain high-speed
track geometry while being subjected to heavy axle loads
The track modulus of slab track is much more uniform than for ballast track
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