Prediction And Assessment For Urban Train-induced Environmental Vibrations

With the rapid expansion of metropolis and the increase of population,the rail traffic,due to its convenience,large capacity,low pollution,fast speed and safety,has become a primary choice to solve the traffic huddle.However,the running train-induced vibrations of ground and buildings affect the living and working environments of human beings,the safety of building structures and the normal performance of precise instruments and high-tech facilities.This problem is becoming more and more serious and has promoted the researches in China and abroad.In this dissertation,the prediction model and assessment method of urban train-induced environmental vibrations are studied,in which the ground lines, underground lines and elevated lines are all considered.The main contents include:(1) The analytical model of urban train-induced free-field and building vibrations is established.The analytical model consists of a 2-D theoretical model of train-track subsystem and a 3-D finite element model of ground-building subsystem.The two subsystems are linked by the force between the vibration source and the propagation path,where the force is calculated from the first subsystem.Such factors which influence the vibrations are considered in the whole analytical model,including rail irregularities,train speeds,train composition,train capacities,train types,soil properties, tunnel bury depths,bridge spans,bearing stiffnesses,building heights and distances to the track,to study how the factors influence ground and building vibrations.(2) The established analytical model is used to study the influence character of each factor through series of parameter combination.The influence characters of each factor are statistically treated to study the quantificational relations between factors and predicted results,and further to establish the urban train-induced free-field and building vibration prediction models for the three cases of ground lines,underground lines and elevated lines,which consist of prediction formulas and modification tables.(3) The analytical models and prediction models for train-induced free-field vibrations and building vibrations are validated by the field experiments at the sites on the Beijing Metro Line 1,Metro Line 5,the Beijing-Guangzhou railway line,and the Shenyang-Haerbin railway line.(4) The assessment method of ground and building peak acceleration levels near railway lines are proposed based on the summary and discussion of evaluation criterions and prediction and evaluation procedures.The applicability of the proposed environmental vibration prediction models is further studied.