Investigating the effect of nailed sleepers on increasing the lateral resistance of ballasted track

Abstract

Up to now, various techniques such as using dual-block sleeper, frictional sleeper, safety cap installation, Xitrack utilization and so forth have been proposed in order to improve the lateral resistance of ballasted railway tracks. In all existing methods, no engagement has been considered for track subgrade in this regard. In this paper, benefiting from the steel-driven nails, a new technique called “nailed sleeper” is introduced for enhancing the lateral resistance of concrete sleepers. In this regard, a 3D numerical model of ballasted track with single tie (sleeper) was developed using ABAQUS software and it was validated using laboratory single tie (sleeper) push test (STPT) results. Thereafter, by inserting two steel nails in the concrete tie of the model, some sensitivity analyses were conducted on the effective parameters of nails such as length, diameter, location through the sleeper and the elasticity modulus of the subgrade. In the next stage, from a structural point of view, the effect of the nail presence on the flexural and shear behavior of B70 concrete sleeper was controlled based on Australian design code AS 1085.14 requirements. As a result of the numerical and analytical analyses, the most appropriate dimensions and locations of nails were defined. Finally, after constructing a nailed B70 sleeper and installing it in a test track, its lateral resistance was evaluated under cyclic loading, and the obtained results were compared with common B70 sleeper at the same track. Consequently, it was observed that using a pair of nails of 40mm in diameter and 1500mm in length can increase the lateral resistance more than 200% compared to the normal condition. This technique can be efficiently used for horizontal anchoring the curved ballasted railway tracks.