| The unban rail transit is in a rapid development period. The network of the unban rail transit, which is innovative, fast and efficient, has been promoted in the main metropolises to comply with the rapid urbanization. With the development of the network, the metro train-induced environmental vibrations have attracted more and more attention, as there have been a lot of collective complaints from the residents along the lines and the strict requirements have also been made from the institutions, which are using the sensitive instrumentations and protecting the historic buildings.However, the existing theoretical analysis models for metro train-induced environmental vibrations cannot well meet the needs of the planning and construction of unban rail transit. Because their computational efficiencies and analysis accuracies are still not very satisfying, especially for some extreme circumstances. Therefore, it still has a very important practical significance to establish a theoretical analysis model for the vibrations in the track, tunnel and ground induced by metro train.Against this background and motivated by the projects of National Science Foundation of China named Research on the Prediction Models for Environmental Vibration Induced by Running Metro Trains (No.51008017) and Research on the Prediction Models for Metro Train-Induced Environmental Vibration Based on Measured Pulse Impact (No.51278043), this dissertation establishes a comprehensive theoretical analysis approach for the vibrations in the track, tunnel and nearby free field induced by passage of metro trains based on the periodic-infinite structure theory. In this dissertation, the theoretical analysis approach for train-induced environmental vibrations and its corresponding calculation models are in-depth researched, the dynamic characteristics of some tracks commonly used in the metro are also studied. The main research contents of this dissertation are as follows:(1) Applying the periodic-infinite structure theory into the track, the methods for solving the dynamic responses of common roadbed track and floating slab track (FST) due to a harmonic moving load are respectively derived in the frequency domain. It is the biggest advantage of these methods that the dynamic response of the whole infinite track can be transformed to be solved within one basic cell of track. (2) Regarding the fixed load as a particular moving load which moves with a speed0, the general wavenumber algorithm for the dynamic response of FST caused by a fixed harmonic load is derived. And then the basic dynamic characteristics of FST are detailed discussed, the influence of track parameters on the dynamic characteristics of FST is also studied.(3) As to the train-track excitation system, based on the solving method for the track dynamic response caused by a harmonic moving load, utilizing the transfer matrix method, the Fourier transformation and the coordinate transformation, the train-track dynamic coupling model (containing the train-common roadbed track dynamic coupling model and the train-floating slab track dynamic coupling model) based on the periodic-infinite structure theory is established in the frequency domain, which adopts the moving excitation model. Through this model, accurate and efficient analysis of the vibration source of train-induced environmental vibration can be carried out.(4) The dynamic characteristics of coupled train-track systems corresponding to the track with DTVI2fasteners, the track with Ⅲ type vibration mitigation fasteners, the prefabricated short FST and the cast-in-place long FST are analyzed and compared through the proposed train-track dynamic coupling model which is based on the periodic-infinite structure theory. Through the analysis, the correctness and applicability of the proposed train-track dynamic coupling model are verified, and the dynamic characteristics of these tracks are clarified.(5) Based on the proposed train-track dynamic coupling model, the sliced finite element-infinite element coupling model (SFEIECM) is creatively established to analyze the vibration response of track base-tunnel-ground system induced by moving metro train. In this model, the finite elements are used to describe the track base, the tunnel and the near field ground, while the infinite elements are used to describe the far field ground, which can provide a good boundary condition. It is the biggest advantage of this model that one can analyze the train-induced vibration response of the three-dimensional track base-tunnel-ground system by only modeling a thin slice range (basic cell) of it along the longitudinal direction. Thus, this model has high calculation efficiency and good calculation ability when it is used to analyze the metro train-induced environmental vibration.(6) The theoretical analysis approach for train-induced environmental vibration, which is composed by the proposed train-track dynamic coupling model and the sliced finite element-infinite element coupling model (SFEIECM), is summarized. And then, its applications on the actual cases are given. Calculation results show that the whole theoretical analysis approach has high accuracy and efficiency due to its comprehensive consideration on the problem and these efficient models in accordance with the reality. |
PDF Full Text Request