Advanced Rail Geotechnology - Ballasted Track

Discrete element modelling of lateral displacement of a granular assembly under cyclic loading

“…A lateral pressure of 10 kPa was applied to the modified side wall that remained constant during the test. This value of confining pressure falls within the range of in-situ confining pressure of 10-30 kPa measured earlier by Indraratna et al [12][13][14], and [17]. Moreover, the field studies carried out by Indraratna et al [12][13][14] for a typical railway track (300 mm ballast depth) illustrated that the confining pressure of the ballast would remain almost constant along its depth.…”

“…It is well known that large particles (rockfills) with much higher internal friction give less settlement. The mid-size particles that are most vulnerable to breakage [16,14] may subsequently pack more densely to give significantly higher settlement. Three walls of the test box were fixed and only the five independent walls on right side were allowed to move laterally.…”

Refurbishment of ballasted track systems; the technical challenges of quality and decision support tools

“…However, contamination of the ballast structure, often known as ballast fouling can quickly exacerbate aged material with limited drainage according to Indraratna et al [15]. The track condition at the junction was very poor with significant coal spillage being a major issue; a very restrictive speed restriction had been in place for some months and it was essential to undertake some palliative repair work urgently to maintain safety and improve performance.…”

Performance Monitoring of Rail Tracks Stabilized by Geosynthetics and Shock Mats: Case Studies at Bulli and Singleton in Australia

“…The layers of geocomposite consisted of bi-axial geogrids placed over layers of nonwoven polypropylene geotextile. The technical specifications of the geosynthetic material used at this site have already been discussed by Indraratna et al (2011b).…”

“…A 30% increase in the stiffness of geogrid has resulted in up to 20% smaller vertical strain on the ballast, while the apertures providing the best interlocking between the geogrids and ballast are between 1.1 and 1.7 times the median particle size (d 50 ) of the ballast. The magnitude of the impact loads vary depending upon irregularities in the wheels or rails, and the dynamic response of the track (Jenkins et al, 1974;Indraratna et al, 2011b). Installing resilient mats such as rubber pads (shock mats) in rail tracks can substantially attenuate the dynamic impact force (Nimbalkar et al, 2012).…”