Comparison of the Mechanical Behavior of Railroad Ballast in a Box Test under Sinusoidal and Realistic Train Loadings Using Discrete Element Method

Abstract

A ballasted track is a popular type of railway track and its use is increasing all over the world. A ballasted track consists of different structural elements like rails, fasteners, sleepers, ballast layer, sub-ballast layer and subgrade. A ballast layer is considered as the main structural element of ballasted tracks; it has a significant contribution to track stability and alignment. After service, periodical maintenance of ballast layer is required to maintain its functionality. Ballast maintenance is a cost and time expensive operation. Better understanding of ballast mechanical behavior leads to better ballast design and efficient maintenance. Discrete Element Method has been used extensively in the literature to understand the mechanical behavior of railroad ballast in a box test. Nevertheless, in the literature most of the studies simulate train loading as pure continuous sinusoidal loading unlike the real train loading. This paper aims to investigate the influence of the simulated train loading on the mechanical behavior of railroad ballast after 1000 loading cycles. There are two simulated train-loading cases used in this study for comparison purposes; continuous sinusoidal loading and a more realistic train loading utilizing the Beam on Elastic Foundation theory. The results show a difference of ballast vertical settlement up to 14% between the two simulated train-loading cases.