Dynamic Characteristics and Parameter Optimization of Floor Vibration Isolation Systems for Metro-Induced Vibrations in Over-Track Buildings

The rapid expansion of urban rail transit networks has raised concerns about metro-induced vibrations in over-track structures. Floor vibration isolation systems provide an adaptable and efficient mitigation strategy, offering flexibility in architectural design while enhancing vibration comfort. This study investigates the dynamic characteristics and parameter optimization of such systems under multi-point excitations. A four-degree-of-freedom (4-DOF) model is developed to analyze the dynamic behavior of the isolation floor system, revealing that the height difference between the horizontal bearing installation plane and the centroid of the isolation plate critically induces “translation–rotation” coupling. Theoretical stability analysis and finite element simulations are employed to evaluate the effects of key parameters, including the isolation plate length, number of bearings, bearing arrangement, isolation frequency, and damping ratio. The results demonstrate that increasing the number of bearings reduces floor acceleration and displacement while improving response uniformity. The optimal isolation frequency range is identified as 3–5 Hz, balancing both isolation efficacy and uniformity. Additionally, increasing the bearing damping ratio to 0.05–0.1 can comprehensively mitigate vibration responses and improve vibration uniformity. Sensitivity analysis confirms that these optimal parameters exhibit strong robustness against ±20% practical deviations, ensuring reliable performance in engineering applications. These findings provide theoretical and practical guidance for optimizing floor isolation systems in over-track buildings, contributing to the sustainable development of urban rail transit networks.