Influence of Metro Vehicle Operation on Adjacent High-Speed Railway Bridge Pier

The growing scale of the high-speed railway network and that of the metro leads to an increasing number of intersections between these two traffic modes. To ensure the structural safety during the construction process of metro tunnels constructed beneath existing high-speed elevated lines, rows of isolation piles between these two different kinds of traffic infrastructures have been widely utilized. However, the vibration isolation effect of these piles during the metro vehicle operation process is still not well studied. In this paper, a model that accounts for the interaction between structures (i.e., high-speed bridge, isolation piles and metro tunnels) and soil foundations is established by employing a three-dimensional finite element method to investigate the vibration isolation effect of the isolation piles. The influence of different design parameters of isolation piles on the vibration characteristics of the complete system is investigated. Besides, this paper summarizes the law of wave peaks formation in the vibration magnification area. The results show that: (i) For surface, vibration isolation effect is influenced greatly by the spacing and diameter of isolation piles. The vibration isolation effect of the isolation pile is weakened considerably with increasing pile net spacing and is enhanced with increasing pile diameter. (ii) For high-speed bridge pier top, geometric parameters of isolation piles have little effect on the isolation efficiency. (iii) The increase of pile diameter and spacing makes wave peaks appear easily in the vibration magnifications region.