Dynamic vertical displacement for ballastless track-subgrade system under high-speed train moving loads

Abstract

In the ballastless high-speed railway, the high-rigidity fastener, the layered subgrade structure and the bottom foundation, which are subjected to the reciprocating high-frequency train effects, transmit and attenuate the energy of the dynamic load. Several recent railway accidents have shown that unsuitable and mismatch stiffness of above components have a significant adverse impact on the dynamic stability of the track-subgrade system. In order to study the influence of component stiffness on the dynamic displacement of a high-speed railway track-subgrade structure, a three-dimensional double-line ballastless track-subgrade finite element model was established. The finite element model is established based on the Beijing-Shanghai double-line ballastless track-subgrade section, and the different stiffness effects of subgrade surface layer, bottom layer, embankment, foundation and fastener are studied. Through the parameter analysis, it was found that the total displacement of the track-subgrade system can be reduced with a higher elastic modulus of the subgrade and embankment layers. The fastener stiffness can significantly affect the rail displacement while has limited effect on the displacement of track-subgrade system. The study also discovered that the variation of the modulus ratio between the upper and lower subgrade layers has a great influence on the surface displacement of the subgrade.