Skip to main content
placeholder image

State-of-the-art design aspects of ballasted rail tracks incorporating particle breakage, role of confining pressure and geosynthetic reinforcement

Conference Paper


Abstract


  • Railways are expected to play a very important role in future transport in Australia, and its large

    network should capture the essential needs for quick and safe, passenger and freight mobility. In

    recent years, the increased demand of heavier and faster trains has posed greater challenges to

    railway industry to improve efficiency and stability of track while reducing the track maintenance costs.

    Centre for Geomechanics and Railway Engineering (GRE) has been the primary Research and

    Development unit in the Australasia for developing and implementing new design and construction

    concepts for modern track upgrading with clear emphasis on applying theory to practice, with the key

    objectives of ensuring enhanced track longevity and minimising track maintenance costs.

    In spite of recent advances in rail track geotechnology, the optimum choice of ballast for track

    design is still considered critical. The major reason is that, ballast aggregates progressively degrade

    under heavy cyclic loading. Research at GRE has shown that a proper understanding of load transfer

    mechanisms and their effect on ballast breakage are important pre-requisites for minimising track

    maintenance costs. Ballast degradation is influenced by various factors including the amplitude and

    number of load cycles, particle gradation, track confining pressure, and the angularity and fracture

    strength of individual grains.

    Recent research projects at GRE and field trials in Bulli (near Wollongong) demonstrated that the

    discarded aggregates from ballast tips could be effectively reused in track construction, if regraded

    and reinforced with geogrids to rejuvenate their internal friction and load carrying capacity. This

    recycling practice would directly decrease the accumulation of discarded ballast, minimise the cost of

    track maintenance and reduce environmental degradation (i.e. less quarrying). Moreover, the use of

    effective sub-surface drainage via geosynthetic drains has been very effective in rapidly dissipating

    cyclic-induced pore water pressures in the soft subgrade (e.g. clay and silts) during the passage of

    trains, and these drains have effectively prevented soil liquefaction (mud pumping). The

    corresponding track behaviour models have been also developed through large-scale laboratory

    simulations and computer-based numerical modelling.

    This state-of-the-art paper describes field trials and prototype laboratory studies carried out to

    quantify the geotechnical behaviour of ballast, including shear strength, particle breakage, effects of

    increased confining pressure, supplemented with predictive and design models for practitioners

    adopting user-friendly analytical and numerical approaches. The paper also highlights the proposed

    changes to current standards of track design and how these new concepts have been implemented

    through actual field trials that demonstrated better performance, in terms of reducing settlement and

    improving drainage. Two case studies are elaborated including the Bulli and Sandgate sites enhanced

    by synthetic grids and geosynthetic drains.

Authors


  •   Indraratna, Buddhima N.
  •   Nimbalkar, Sanjay S. (external author)
  •   Rujikiatkamjorn, Cholachat (external author)
  •   Christie, David (external author)

Publication Date


  • 2011

Citation


  • Indraratna, B., Nimbalkar, S., Rujikiatkamjorn, C. & Christie, D. (2011). State-of-the-art design aspects of ballasted rail tracks incorporating particle breakage, role of confining pressure and geosynthetic reinforcement. 9th World Congress on Railway Research (pp. 1-13). Lille, France:

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers/4467

Start Page


  • 1

End Page


  • 13

Place Of Publication


  • Lille, France

Abstract


  • Railways are expected to play a very important role in future transport in Australia, and its large

    network should capture the essential needs for quick and safe, passenger and freight mobility. In

    recent years, the increased demand of heavier and faster trains has posed greater challenges to

    railway industry to improve efficiency and stability of track while reducing the track maintenance costs.

    Centre for Geomechanics and Railway Engineering (GRE) has been the primary Research and

    Development unit in the Australasia for developing and implementing new design and construction

    concepts for modern track upgrading with clear emphasis on applying theory to practice, with the key

    objectives of ensuring enhanced track longevity and minimising track maintenance costs.

    In spite of recent advances in rail track geotechnology, the optimum choice of ballast for track

    design is still considered critical. The major reason is that, ballast aggregates progressively degrade

    under heavy cyclic loading. Research at GRE has shown that a proper understanding of load transfer

    mechanisms and their effect on ballast breakage are important pre-requisites for minimising track

    maintenance costs. Ballast degradation is influenced by various factors including the amplitude and

    number of load cycles, particle gradation, track confining pressure, and the angularity and fracture

    strength of individual grains.

    Recent research projects at GRE and field trials in Bulli (near Wollongong) demonstrated that the

    discarded aggregates from ballast tips could be effectively reused in track construction, if regraded

    and reinforced with geogrids to rejuvenate their internal friction and load carrying capacity. This

    recycling practice would directly decrease the accumulation of discarded ballast, minimise the cost of

    track maintenance and reduce environmental degradation (i.e. less quarrying). Moreover, the use of

    effective sub-surface drainage via geosynthetic drains has been very effective in rapidly dissipating

    cyclic-induced pore water pressures in the soft subgrade (e.g. clay and silts) during the passage of

    trains, and these drains have effectively prevented soil liquefaction (mud pumping). The

    corresponding track behaviour models have been also developed through large-scale laboratory

    simulations and computer-based numerical modelling.

    This state-of-the-art paper describes field trials and prototype laboratory studies carried out to

    quantify the geotechnical behaviour of ballast, including shear strength, particle breakage, effects of

    increased confining pressure, supplemented with predictive and design models for practitioners

    adopting user-friendly analytical and numerical approaches. The paper also highlights the proposed

    changes to current standards of track design and how these new concepts have been implemented

    through actual field trials that demonstrated better performance, in terms of reducing settlement and

    improving drainage. Two case studies are elaborated including the Bulli and Sandgate sites enhanced

    by synthetic grids and geosynthetic drains.

Authors


  •   Indraratna, Buddhima N.
  •   Nimbalkar, Sanjay S. (external author)
  •   Rujikiatkamjorn, Cholachat (external author)
  •   Christie, David (external author)

Publication Date


  • 2011

Citation


  • Indraratna, B., Nimbalkar, S., Rujikiatkamjorn, C. & Christie, D. (2011). State-of-the-art design aspects of ballasted rail tracks incorporating particle breakage, role of confining pressure and geosynthetic reinforcement. 9th World Congress on Railway Research (pp. 1-13). Lille, France:

Ro Metadata Url


  • http://ro.uow.edu.au/eispapers/4467

Start Page


  • 1

End Page


  • 13

Place Of Publication


  • Lille, France