Studies On Surrounding Soil's Vibration Performance As Light Rail Train Passing Viaduct

The rail traffic, due to its convenience, capacity, speed and safety, is becoming a primary choice to ease the heavy city traffic. However, vibrations of surrounding ground and buildings as induced by the running trains have a strong impact on people's health, living & working environment, the safety of building structure and the normal performance of precise instrument, which arouse researchers' attention greatly both home and abroad.The attenuation in this thesis is systematically analyzed of ambient vibrations caused by light-rail trains when passing viaduct. Firstly, on the basis of former research work, the developing status, research methods and current achievements for this research subject are briefly introduced. And moreover, domestic and oversea calculating models, parameter selection, evaluation criterion etc for surrounding soil's vibrations as induced by light-rail traffic are compared separately.Based on above the model is further divided into two sub-models as vehicle-bridge model and pier-soil model, which emphatically analyzes the impact of artificial boundary selection, vehicle speed, and mutual effect of soil-structure on the result. For vehicle-bridge model, load series model is used to build its dynamic equation and solving by iterative method. For pier-soil model, three important queries are discussed as: foundation soil model, mutual effect of structure-soil and artificial boundary.At the end of the article, taking ten expanding 30m simple support beam in Wuhan light-rail engineering for example, first a vehicle-bridge dynamic analysis model is constructed based on moving load series passing bridge to calculate the reaction history of pier support. Then, a three-dimensional finite element model for dynamic analysis of pier-soil is established under three artificial boundary conditions. Dynamic responses of ground under elastic state is calculated by applying the large general software ANSYS. The attenuation of displacement, speed and vibration level are highlight discussed with some significant conclusions. Via numerical calculation, the displacement and acceleration values rebound at certain distance, which is the same as the measured. The results indicate that the attenuation of ground vibration is coherent with measured one. The building model and analysis results can be provided for the analysis of environmental vibration generated by light-rail running train on viaduct.