Virtual Inversion Of Source Parameters Of Environmental Vibration Caused By Rail Traffic

Urban rail traffic is one of the most efficient solutions to urban traffic problems in the urbanization. Nowadays, China is in the process of urbanization, a large number of metro, light track and elevated railroads are constructed in many cities. Environmental vibration problems due to rail traffic are getting severer from two reasons, one is the urban rail traffic are closer to the living environment of people, the other is the people's increasing requirements for better living circumstances. Therefore, the research on environmental vibration due to rail traffic attracts more and more attentions.The model to predict the ground-borne vibrations from urban rail traffic consists of three subsystems, source, path and receiver. In this thesis, the goal is the former two subsystems. Genetic algorithm (GA) is adopted in virtual inversion of the source parameter. The contents of this thesis can be summarized as follows:1. The development of urban rail traffic in the world is reviewed. Then, the research goal and the main research ways are summarized, the analytical approaches are emphasized.2. In this thesis, the ground-borne vibrations due to the urban rail traffic with rail joints will be investigated. The impact force from wheel-rail contact at the rail end can be considered as a tremor on the surface of an elastic half space. By means of an analytical solution of the vertical displacement due to the vertical tremor on the surface of an elastic half space, the vertical displacement can be calculated. And the vertical displacement can be verified by the transfer matrix method, when a tremor is on the surface of multilayered elastic half space.3. An example is given. Supposed that 20 coaches(each coach contains 4 wheel pairs) pass over 15 rails, the vertical displacement overlap of a point which is 20 meters away from the rails in time domain can be obtained by the analytical solution, and the specification of the vertical displacement calculation on the ground surface is shown.4. The history, applications and properties of GA are reviewed. The detailed steps of GA is investigated and given out. The main application steps of GA include the determination of problem's model, objective function, fitness function, encoding, selection operator, crossover operator, mutation operator, initialization of the population, and operation parameters. The GA method used in this paper is presented.5. The method of virtual inversion is presented. The source parameter is inversed by virtual inversion method, combined the vertical displacement overlap in time domain with GA.