ABSTRACT
In order to compete with other modes of transportation, rail industries face challenges to minimise track maintenance costs, and to find alternative materials and approaches to improve the track performance. The track should be designed to withstand large cyclic train loadings to provide protection to subgrade soils against both progressive shear failure and excessive plastic deformation. The design of track should also consider the deterioration of ballast due to breakage and subsequent implications on the track deformations. The potential use of geosynthetics in the improvement of track stability and reducing the maintenance cost is well established. The stabilisation of the track by means of geogrids and prefabricated vertical drains that provide confinement to the ballast layer in addition to rapid radial drainage, assures a more resilient longterm performance of the ballast and formation layer [1, 2, 3, 4]. Two field trials were employed for validating the numerical analysis. The first field trial was conducted on a section of a fully instrumented railway track along the coastal town of Bulli, in New South Wales, Australia. The main objectives were to study the benefits of a geocomposite (i.e. combination of biaxial geogrid and non-woven polypropylene geotextile) installed at the ballast-capping interface, and to evaluate the performance of moderately graded recycled ballast in comparison with traditionally used uniform fresh ballast. The second field trial was carried out at the Sandgate Rail Grade Separation Project located between the regional towns of Maitland and Newcastle, in Eastern New South Wales, to verify the performance of a track built on thick soft estuarine clay, stabilised by prefabricated vertical drains (PVDs).
