Investigation of Train-Induced Micro-Vibrations on Precision Instruments in an Adjacent Building with Floating Slab Tracks

Rail transit in proximity to vibration-sensitive facilities presents significant challenges for the stable operation of precision instruments due to train-induced micro-vibrations. This study investigates the effectiveness of steel-spring floating slab tracks (FSTs) in mitigating such dynamic disturbances in a laboratory building situated above an operational railway tunnel. A coupled vehicle–track dynamic model and a detailed three-dimensional finite element model of the track–tunnel–soil–building system were developed to predict the vibration induced by two trains passing each other at 120 km/h. The models were solved by employing a full-process iterative method, and validated using field measurement data. Simulation results demonstrate that the FST significantly reduces environmental vibration levels in both vertical and horizontal directions. Despite these improvements, predicted floor-level vibrations still exceed ambient background levels in specific frequency bands—namely, vertical vibrations above 4 Hz, and horizontal vibrations within 8–12.5 Hz and 31.5–80 Hz. The vibration velocities at frequencies around 63 Hz and 10 Hz approach the vibration limit curve of the precision instruments. Importantly, the vibration amplitudes remain within acceptable limits for precision operations: vertical vibrations comply with Vibration Criterion B (VC-B), while horizontal vibrations meet the stricter VC-E standard. Sensitive equipment is advised to be located in rooms on lower floors and farther away from the railway. As the distance between the room location and the railway increases, the rate of increase in vibration with floor height gradually decreases. As the floor height increases, the rate of decrease in vibration with increasing distance from the railway increases. Ground surface vibration analysis reveals an undulating attenuation pattern with distance, influenced by wave interference and system resonances. This work offers a validated simulation framework and practical insights into the mitigation of micro-vibrations in railway-adjacent environments, informing the design and siting of precision engineering facilities.