Analysis of Structural Vibrations due to Passage of Underground Trains

During the last decades, the railway traffic in densely populated areas has increased. At the same time, passenger trains have become faster and freight trains have become heavier. Consequently, trains are an increasing source of ground vibration, which may be a nuisance to people, buildings and sensitive equipment. In this research, a two-dimensional dynamic system, including underground train, sleeper, rail pad, tunnel, soil and adjacent structure is analyzed implementing a linear time history dynamic analysis. The purpose is a parametric study about the factors affecting peak responses of structures (acceleration, velocity and displacement). The effects of train velocity, soil properties, natural period of structure and height of tunnel, are investigated. Train movement is modeled by a series of moving loads. The set of ballast, rail pads, sleepers and tunnel are modeled with appropriate elements. The surrounding soil and structure on the ground, are modeled with plane strain and frame elements, respectively. Behavior of the system is assumed to be linearly elastic. The time history analysis results in recognizing the critical cases of response and the factors important for it. The critical conditions for the vibrations of the ground surface, relief of the building occupants, and the structural behavior are determined.