Track formation behaviour in arid environments

Australian Rail Track Corporation's (ARTC's) line between Perth and Melbourne suffers in places from recurring formation problems. ARTC embarked upon a study aimed at understanding the mechanism(s) better. A distinct link was noticed between the problems and geology, suggesting a geotechnical cause. Three, widely separated, sites were selected for study. Geotechnical investigations indicated that soil moisture content beneath the track varied surprisingly little during the year, but it was always higher than that of the surrounding ground. This was attributed to the ballast funnelling water into the subgrade during wet periods and subsequently protecting the surface from evaporation. Corresponding effects were observed in terms of soil suction and soil strength. Survey showed that the track normally moved downwards, even when the surrounding ground heaved. It is believed that this settlement is due to plastic strain in the sub-grade resulting from repeated train loading and not shrink-swell behaviour. Based on the data collected, it is suggested that, during and immediately after wet periods, surplus water in the ballast can lead to temporary softening of the subgrade. The method proposed by Li and Selig (1998) allows plastic strain to be calculated for a given soil strength and loading regime. This paper suggests that the effects of periodic softening might also have to be accounted for, if the method is going to be applied successfully in arid and semi-arid conditions.

Media Info

  • Pagination: 15p. ; PDF
  • Monograph Title: Cost efficient railways through engineering: CORE 2002: conference on railway engineering, November 10-13 2002, Wollongong, New South Wales, Australia

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Filing Info

  • Accession Number: 01532260
  • Record Type: Publication
  • Source Agency: ARRB
  • Files: ATRI
  • Created Date: Jul 29 2014 1:29PM