Investigation of the Inertial Characteristics of the Railway Track System

Elastic foundation models offer a computationally efficient way for the qualitative analysis of the railway track system. However, the inertial characteristics of the foundation are neglected while modeling the railway track system using those models. This paper investigates the effect of incorporating the mass of the foundation on the behavior of the elastic foundation models under the dynamic train loading. The railway track system is idealized as an infinite Euler–Bernoulli beam resting on a continuous two-layer system with top and bottom layer denoting the ballast and subgrade, respectively. The ballast layer is modeled using inertial elastic shear elements and the subgrade by inertial viscoelastic elements. A time-domain deflection analysis of the proposed model is carried out for various ranges of train speeds. It is found that the incorporation of the inertial characteristics of the substructural system may lead to significant underestimation in the critical velocity values (by up to 85%). Further, the deflection magnitudes and the critical velocity of the system are found to be highly sensitive to the stiffness of the substructure. Higher deflection and lower critical velocity values are observed in the case of soft subgrade as compared to those in the stiff subgrade. Finally, the incorporation of the shear parameter associated with the ballast significantly decreases the deflection magnitudes.