Contribution of Base, Crib, and Shoulder Ballast to the Lateral Sliding Resistance of Railway Track: A Geotechnical Perspective

Abstract

The sleeper to ballast interface plays a crucial role in the stability of ballasted railway track, transferring both vertical and lateral loads safely from the superstructure to the sub-base. However, current conceptual models for the behaviour of the interface are incomplete and too simplistic to assess the response of the track system to the loads exerted by modern trains. For example, the increased curving speeds associated with tilting trains introduce potentially significant combinations of vertical, lateral, and moment loading which are not explicitly considered in current assessment procedures. Also, the relative contributions of the base, crib, and shoulder ballast to lateral sliding resistance are at present poorly quantified. The behaviour of the sleeper to ballast interface was investigated in a series of tests in an apparatus capable of applying combinations of load representative of real trains. This article presents test data quantifying the relative contributions to total sliding resistance of the base, crib, and shoulder. New calculations are presented, which enable the resistance from the crib and various sizes of shoulder ballast to be quantified. The results of the experiments and calculations are compared with each other and with the literature, and reasonably consistent patterns of behaviour are identified.

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.…”

Behaviour of clay-fouled ballast under drained triaxial testing

“…It is usually composed of medium to coarse gravel-sized particles (10-60 mm). Its main functions (Priest et al, 2010;Indraratna et al, 2011;Le Pen & Powrie, 2011) are to (a) transfer the train load from sleepers to the sub-ballast layer and subgrade with an acceptable distribution of stress with depth and associated deformation (b) provide sufficient lateral confining pressure to the track (c) provide a free-draining condition.…”

A laboratory investigation to assess the functioning of railway ballast with and without geogrids

“…Le Pen (2008), and Le Pen and Powrie (2011) have also reported similar values of confining pressure considering the effect of the shoulder ballast. Moreover, the field studies carried out by Indraratna et al (2010 and for a typical railway track (300 mm ballast depth), illustrated that the confining pressure of the ballast would remain almost constant along its depth.…”