Study On Free Field Vibrations Induced By Metro Trains And Their Influences On Surrounding Buildings

In 1863, the first subway in the world was built in England. During the past 150 years, as the rapid development of economy, subway transit system has been widely applied in many countries owing to its large capacity, high efficiency and low pollution. At the same time, there arose the underground train-induced problem of vibration disturbance to the nearby environment. This has become a publicly concerned problem, and has been studied by experts.The aim of this dissertation is to assess and predict the effect of vibrations induced by a subway runnel and study the characteristics of free-field and buildings vibrations due to underground trains and their transmission laws. The study consists of the simulations of the train-track system vibration, which provide the excitation loads of moving trains onto the tunnel structure, and the calculation of the track tunnel-ground system vibration, by which the transmitting properties of ground acceleration and velocities are studied. In the model, the rail is simulated as an Euler-Bernoulli beam resting on Winkler foundation in the vertical plane, the load excited by single wheel onto the runnel is expressed with the influence of wheel-rail contact interaction, and the dynamic load of the whole metro train onto the tunnel is obtained by superposition.With the source-transmitter-receiver mathematical model as the train-soil-structure (TSS) interaction model, taking into account sub-model parameters such as the speed of the train, train axle load, typical geotechnical conditions of the ground, depth of the tunnel under ground and the sensitivity of the nearby buildings, the analysis is carried out over the entire system using the dynamic finite element (FE) method in the time domain. Variations of free-field and building vibration with various influencing factors is showed in this dissertation.