Influence of new vibration-reducing track with trapezoidal sleepers on the vibration of subway line foundation structure and overtrack buildings

With the rapid development of urban subway construction, environmental vibrations induced by train operations have drawn increasing attention from various stakeholders. The evaluation of subway-induced environmental vibrations serves as a primary basis for vibration mitigation design and impact control. Therefore, it is essential to investigate the propagation characteristics of train-induced environmental vibrations along subway lines. In this work, a prediction method for subway train-induced environmental vibrations is proposed by integrating train-track coupled dynamics and the finite element method. A new type of vibration-reducing track with trapezoidal sleepers (VRTTS) is applied in the rail vibration attenuation design. The moving train is modeled as a multi-rigid-body system and the track structure as a flexible body. A vehicle-track interaction model considering wheel-rail dynamic contact relationships is established to obtain the dynamic wheel-rail contact forces. Subsequently, a VRTTS-tunnel-soil-building finite element model is developed using ANSYS. The wheel-rail forces are then treated as excitation sources for the substructure, and the propagation characteristics of train-induced vibrations along the entire transmission path are investigated. Furthermore, numerical examples are performed to analyze the influence of various parameters, such as fastener stiffness, the stiffness and damping of the vibration-reducing pad, on the time-frequency characteristics of vibrations at different structural components. The results indicate that vibration-reducing pads can effectively mitigate the transmission of train-induced vibrations to the foundation and buildings. Increasing the stiffness and damping of the pads significantly reduces low-frequency vibrations in the tunnel and buildings but may amplify mid- to high-frequency vibrations to some extent. Therefore, the parameters of vibration-reducing pads should be reasonably determined based on building function and requirements. The proposed method provides an effective approach for evaluating train-induced environmental vibrations and designing vibration mitigation measures, and it offers theoretical guidance for the parameter design of VRTTS.