Modelling ground vibration from a high-speed railway track resting on a periodic pile-plank structure-enhanced embankment

Abstract

Pile-plank structure-enhanced embankments are used in high-speed railways, mainly for controlling embankment settlement and frost heave. The effect of such embankment on train-induced ground vibration has yet received little attention. In this paper, a model is developed to predict ground vibration from such a high-speed railway. In the model, the track/embankment/ground system is idealised as an infinitely long periodic structure. The periodicity is created by the piles which are arranged periodically in the track direction to support the plank and the track. The fictitious pile method is used to divide the periodic track/embankment/ground system into two systems interacting with each other. One is a structure formed by the track, plank, pure soil embankment and ground, all of which are assumed to be uniform in the track direction. Therefore, this structure is uniform in the track direction and termed the 2.5D track/ground structure. The other is an infinite number of fictitious piles which are arranged periodically in the track direction (termed the fictitious piles). The 2.5D finite element method (2.5D FEM) and the Floquet transform are combined to deal with the interaction between the two systems, making the model a 2D FE mesh based and convenient to consider the moving of a train along the track. The focus of the paper is modelling methodology and therefore only preliminary results are produced from the model. The results show that, the pile-plank structure studied in this paper can largely reduce low frequency ground vibrations, for which other measures of ground vibration mitigation are often difficult to apply, but it may also increase ground vibration at other frequencies, depending on the observation location on the ground surface.