Method for Railroad Track Foundation Design. II: Applications

Li, Dingqing; Selig, Ernest T.

doi:10.1061/(asce)1090-0241(1998)124:4(323)

Cited by 81 publications

(30 citation statements)

References 3 publications

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“…Fig. 11(b) illustrates the calculated DAF as a function of train speed V, together with the predictions made from other studies (i.e., Li and Selig 1998;Esveld 2001). The conventional approaches over-predicted the value of DAF within its range of application (i.e., V ≤ 100 km=h).…”

Section: Dynamic Amplification Factormentioning

confidence: 80%

“…In conventional practice, the dynamic amplification factor (DAF) is used as a function of static (wheel) stress and train velocity to obtain the equivalent dynamic stress (Li and Selig 1998;Esveld 2001). In the present study it was used to study the possible implications that increased train speeds and axle loads would have on the ballast contact stresses.…”

Section: Dynamic Amplification Factormentioning

confidence: 99%

See 1 more Smart Citation

Improved Performance of Ballasted Rail Track Using Geosynthetics and Rubber Shockmat

Nimbalkar

Indraratna

2016

J. Geotech. Geoenviron. Eng.

109

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Large repetitive wheel loads from heavy haul and passenger trains can cause significant track deformation that leads to poor track geometry and safety issues. The inclusion of geosynthetics and rubber mats (i.e., shockmat) in critical sections in the track for reducing these adverse effects was further examined through an extensive field trial in the town of Singleton, New South Wales (NSW), Australia. Four types of geosynthetics and a shockmat were installed below the ballast layer in selected sections of track constructed on three different subgrades (soft alluvial clay, hard rock, and concrete bridge), and the performance of the instrumented track was monitored for five years under in-service conditions including tamping operations. The measured stress-deformation response indicates that the geosynthetics effec-tively control the long-term and transient strains in the ballast layer, with the obvious benefit of reducing maintenance costs. The study also showed that the aperture size of geogrids in the range of 1.1 times the mean particle size of the ballast was most effective. The placement of shockmat on a concrete bridge contributed to reduced ballast breakage. The dynamic amplification of stresses induced by moving trains was observed, and it became more pronounced at higher axle loads and train speeds. The dynamic track modulus was evaluated adopting the concept of modified beam on an elastic foundation (BOEF), and this approach was found to be largely influenced by the axle load, train speed, placement of synthetic inclusions, and type of subgrade. Abstract: Large repetitive wheel loads from heavy haul and passenger trains can cause significant track deformation that leads to poor track geometry and safety issues. The inclusion of geosynthetics and rubber mats (i.e., shockmat) in critical sections in the track for reducing these adverse effects was further examined through an extensive field trial in the town of Singleton, New South Wales (NSW), Australia. Four types of geosynthetics and a shockmat were installed below the ballast layer in selected sections of track constructed on three different subgrades (soft alluvial clay, hard rock, and concrete bridge), and the performance of the instrumented track was monitored for five years under in-service conditions including tamping operations. The measured stress-deformation response indicates that the geosynthetics effectively control the long-term and transient strains in the ballast layer, with the obvious benefit of reducing maintenance costs. The study also showed that the aperture size of geogrids in the range of 1.1 times the mean particle size of the ballast was most effective. The placement of shockmat on a concrete bridge contributed to reduced ballast breakage. The dynamic amplification of stresses induced by moving trains was observed, and it became more pronounced at higher axle loads and train speeds. The dynamic track modulus was evaluated adopting the concept of modified beam on an elastic foundation (BOEF), and this approach was foun...

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Section: Dynamic Amplification Factormentioning

confidence: 80%

Section: Dynamic Amplification Factormentioning

confidence: 99%

Improved Performance of Ballasted Rail Track Using Geosynthetics and Rubber Shockmat

Nimbalkar

Indraratna

2016

J. Geotech. Geoenviron. Eng.

109

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“…The track foundation design method by Li and Selig [13,14] is based on two parameters, which aim to prevent the two most common track subgrade failures caused by repetitive loading on track foundations. The measurements at Bloubank will be evaluated against these norms in the following paragraphs.…”

Section: Track Foundation Design Parametersmentioning

confidence: 99%

Design Life Prediction of a Heavy Haul Track Foundation

Gräbe

Shaw

2010

Proceedings of the Institution of Mechanical Engineers, Part F:

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Transnet Freight Rail monitors the behaviour of a new track foundation, constructed in 2004, on the South African Coal Line. This site forms part of a major rehabilitation project, aimed at increasing the capacity of the line to sustain future growth in annual tonnage. Sophisticated instrumentation is used to measure resilient and permanent deformation of the track foundation. Preliminary results of this research were published shortly after the construction of the new track foundation. Results of the permanent deformation, gathered over a period of 5 years, are now presented to provide new insight into the long-term behaviour of track foundations. Permanent deformation measurements are used to calculate the expected design life of a track foundation. The results are used to predict permanent deformation and ultimately the design life of the track foundation under heavy haul loading conditions. The research provides a scientific basis for planning foundation rehabilitation in the light of sustained capital expansion and projected tonnage increase on the Coal Line and other heavy haul lines.

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“…In analysis, the subsoil was still assumed to be homogeneous, with no facility to assess the effect of layers of different stiffness on track and sub-base performance. Li & Selig (1998a, 1998b) developed a more analytical railway design methodology based on the combined use of a multilayered linear elastic finite element (FE) model coupled with extensive laboratory testing. The FE model is used to calculate stresses in the subgrade taking account of the potentially different stiffnesses of the ballast, sub-ballast and natural ground.…”

Section: Introductionmentioning

confidence: 99%

Measurements of transient ground movements below a ballasted railway line

Priest¹,

Powrie²,

Le³

et al. 2010

Géotechnique

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This paper presents the results of a detailed investigation into the ground deformations that occur under a railway line during the passage of a train. Four horizontal boreholes were installed at different depths below a ballasted railway track. Ground deformations were measured using geophones at set distances from the centreline of the track within each borehole. The results show vertical displacements reducing with depth, from a maximum at the sleeper. Sleeper displacements are dominated by pairs of bogies at the ends of adjacent wagons (which have a frequency of loading 1 Hz), although the effects of individual bogies (2 Hz) and axles (6 Hz) are also apparent. Higher loading frequencies attenuate with depth so that at a depth of 0 . 780 m below the sleeper soffit no axles are visible within the displacement data and by a depth of 1 . 98 m only the combined effect of pairs of adjacent bogies is apparent. In contrast, longitudinal horizontal motion is greatest at a depth of 0 . 78 m below the sleeper soffit, and the longitudinal horizontal displacements at the sleeper and at a depth of 0 . 78 m are dominated by the individual axles (,6 Hz). By a depth of 1 . 98 m, the longitudinal horizontal motion is dominated by the bogie pairs. A dynamic linear-elastic two-dimensional finite element model was developed and validated using the measured displacements.

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Method for Railroad Track Foundation Design. II: Applications

Cited by 81 publications

References 3 publications

Improved Performance of Ballasted Rail Track Using Geosynthetics and Rubber Shockmat

Improved Performance of Ballasted Rail Track Using Geosynthetics and Rubber Shockmat

Design Life Prediction of a Heavy Haul Track Foundation

Measurements of transient ground movements below a ballasted railway line

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