Improvement of the fictitious pile-based model for more efficiently predicting ground vibration from a pile-plank high-speed railway track

A previously developed model based on the fictitious pile method is improved and extended for more efficiently predicting ground vibration generated by high-speed trains running along a railway track resting on a periodic pile-plank structure-enhanced embankment. The extension and improvement are achieved from four aspects: (1) bending vibration, in addition to axial vibration, is allowed for the piles; (2) the periodically arranged fictitious piles are modelled using finite beam elements, enabling direct coupling in the Floquet-wavenumber domain with the 2.5D finite element model of the ground, avoiding lengthy calculations of strain and the establishment of the Fredholm integral equations of the second kind; (3) the 2.5D perfectly match layer (PML) technique is used to reduce the pile–ground interaction model, enabling more efficient calculation of the interaction forces between the fictitious piles and the ground; (4) the same 2.5D PML is applied to a wide model for far-field ground vibration calculation. The improved model is then used to predict ground vibration for a typical high-speed train running along a typical pile-plank high-speed railway track, to demonstrate the effect of several pile-plank design parameters on ground vibration, and to assess the effect of pile bending.