Site investigation for permanent way maintenance design

The determination of the geotechnical profile of railway embankments or cuttings is an essential prerequisite for remedial or new works design. Conventional site investigation techniques using standard cable percussive and rotary drilling plant are rarely feasible for permanent way investigations due to the requirement for safety zones and the problems associated with securing possessions for this type of work. This has forced the industry to find alternative methods of investigation particularly suited to moderately steep slopes. The constraints do involve a degree of compromise but by using the techniques in a phased manner, decisions on the need for greater sophistication and cost can be focussed on the areas of major problem. Embankments form a significant part of the railway network and these are frequently composed predominantly of clay fills. The history of embankment construction is often not well documented and it is suspected that the only compaction was by the vehicles transporting the clay along the route. The majority of embankments are therefore composed of poorly compacted fills. The investigation of embankments showing signs of distress requires not only reasonable quality sampling and in situ testing, but also monitoring. Geotechnics Limited has established a range of investigation techniques which can address these requirements and includes window sampling, dynamic probing, mini auger drilling and hand excavated trial pits. Hand vane testing and the in situ CBR probe can provide invaluable data on strength and sub-base quality. A range of monitoring installations can be provided including slip indicators, piezometers and inclinometers. There are of course some embankments which do not lend themselves to investigation by lightweight equipment and a much more costly investigation using larger equipment capable of being dismantled and re-erected at exploratory hole locations or lifted on by crane becomes a necessity, usually on scaffold platforms.

Language

  • English

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Filing Info

  • Accession Number: 01011797
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • ISBN: 0-947644-43-1
  • Files: ITRD
  • Created Date: Dec 19 2005 3:32PM