| With the rapid development of the national economy, the construction of railway, subway and urban rail-viaduct system have been reached a new climax in present period. At the same time, the influence of the vibration caused by the moving vehicles on the near environment has been increased and paid close attention to. Up to now, the methods used for the evaluation and forecasting of the environmental vibration along the whole railway have still been the field survey and some empirical formulas which will result in certain errors, the systematic study and the quantificational analysis on this problem have not been performed in our country. So it is impossible to instruct the design and construction of rail transportation effectively. In order to evaluate the vibration along railway correctly, it is necessary to lucubrate the dynamic response of ground bearing the moving loads of vehicle.In this paper, regarding the rail, viaduct and ground as study objects, the response of ground under the moving loads on rails are analyzed in detail and the propagation characteristic of vibration in the ground are concluded. In addition, two kinds of vibration-decreasing measures are applied on the rail lines with big vibration, and the effects of decreasing vibration are also analyzed comparatively.The main study includes the following aspects.1. Introducing some rail models in existence and their respective research direction in point. Considering our purpose is studying the dynamic response of ground under the speedy moving loads, the Euler beam model and Tirnoshenko beam model are selected here to be rail models. In this particular condition that studying the dynamic response of rail system under the speedy moving loads, it has been already proved by the calculation results that the rail models and calculating methods applied in this problem are rational.2. Taking account of the direct effect of ground vibration on buildings, the ground responses caused by the moving loads is studied in detail. Because of the complication of ground condition, the ground is regarded as continuous layers and each layer of soil is defined as a uniform and elastic object. By solving the wave equation (Navier Equation) of three-dimensional elastic object, the results of groundunder moving loads in wave number ?frequency field are obtained, then through the rapid Fourier reverse transform, the results in space-time field are obtained. Based on the resolving algorithm of continuous-layer method, the time order analyzing curves, acceleration curves and the response spectra of transfer function at the different points of the ground and at the same point on the different ground conditions are gained. It demonstrates that the responses of ground in x, y and z axial directions all change by time, and the obvious wave propagation appears in ground. For different observing points on the same ground condition, at more distant points from the load line, the less swings are found, that is to say, vibration possesses the obvious characteristic of attenuation.3. The ground vibration caused by load of vehicle in light railway system is analyzed as well. Different from the common railway and subway, the viaduct is the main structural member in light railway system, which is studied in specialty in this paper. The effect of viaduct system on near environment is generated through the column of viaduct, so the characteristics of loads are that the action points do not change but the values change with time. For the modeling of this kind of problem, because the time-order curves of viaduct column bearing the loads of vehicles are expect to get, the present finite element analysis software ?ANSYS can be used to solve it quite well. So ANSYS is applied here to calculate the response of ground under moving loads in light railway system. At the locations with the big vibration, two measures for vibration-diminishing ?Wave Impeding Block and Open Drain for Isolating Vibration are constructed, and the effective of vibration-diminishing is analyzed...
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