Effect of periodic vibration-isolation piles on soil vibration in deep-buried tunnels of suburban railways

This study aims to investigate the impact of isolation piles on soil vibrations in the environment surrounding suburban railways. Initially, a comprehensive numerical model of the train was established to simulate the wheel-rail interaction forces, which were then applied to a three-dimensional coupled track-soil model. The accuracy of the model was validated through comparison with measured data. The focus of the research is to analyze the vibration isolation effects of single-row, double-row, and triple-row piles, with particular attention to the influence of pile spacing in double-row piles on isolation effectiveness. The study found that the effectiveness of isolation piles in reducing soil vibration acceleration within a depth range of 0 m to 2 m decreases as the pile spacing increases. When the pile spacing reaches 2 times the pile radius, single-row piles exhibit the best vibration isolation effect. For reducing peak soil acceleration within a depth range of 4 m to 8 m, single-row piles are most effective when the pile spacing exceeds 1 times the pile radius. To attenuate peak soil acceleration at depths greater than 6 m, the pile spacing for single-row and double-row piles should be set at 0.5 times the pile radius, while triple-row piles should have a spacing of 1 times the pile radius. In terms of reducing peak soil velocity, single-row piles demonstrate better vibration isolation effects. To reduce peak velocity in soil at depths greater than 2 m, the pile spacing for single-row and double-row piles should be set at 0.5 times the pile radius, while triple-row piles should be spaced at 1 times the pile radius. For reducing peak soil displacement, single-row piles should be used, with optimal results achieved at a spacing of 1 times the pile radius.