Influence of Rubber Inclusion on the Dynamic Response of Rail Track

Abstract

Heavier and faster trains have motivated researchers to seek better ways to absorb the increasing amount of energy imparted to rail foundations and mitigate track deterioration. In recent years, resilient rubber products have attracted more attention due to the high level of damping and the associated energy absorbing capacity of rubber. However, because rubber granules have lower shear strength and higher compressibility compared with natural rock aggregates, a better understanding of how rubber inclusions can influence the track system is imperative, especially before putting these recycled resilient materials into practice. In this paper, the performance of rail track incorporating an alternative subballast layer, i.e., a synthetic energy absorbing layer (SEAL) consisting of a mixture of granulated rubber and mining waste is evaluated through large-scale prismoidal triaxial tests and a computational dynamic model. It is revealed that the amount of granulated rubber in SEAL composites has a significant influence on the dynamic behavior of the track. Fundamentally, increasing the amount of rubber within SEAL leads to a higher vertical deformation, increased energy absorbing capacity, and a higher damping ratio and vibration level, while reducing the ballast degradation, track stiffness, and lateral movement (dilation) of the track. It has been found that 10% of rubber by mass is the optimal amount of rubber to be included in SEAL. This amount of rubber will ensure that a ballasted track can efficiently reduce the dynamic contact pressure at the interface between different track layers (i.e., sleeper, ballast, subballast, and subgrade), and reduce the lateral spread (dilation) and breakage of ballast without generating excess vibration and settlement comparing with traditional track materials.