Embankment-gound Vibration Generated By Train Moving Loads And Vibration Isolation

With the speed increasing of train, the vibration of rail, embankment and ground increasing accordingly. Therefore many new geotechnical problems are introduced. Including the instability of the high-speed train moving on the soft ground, the destruction of the rail bed, the influence of environmental vibrations to the health of residents along the rail road line and etc. These problems attract attention of trail engineers and researchers.In this thesis, a coupled physical model for track-embankment-underlying ground dynamic interaction under moving load was developed by employing the 2.5 dimensional finite element numerical methods firstly. Then the interaction of track, embankment and underlying ground, the vibration and the dynamic responses of threes-dimensional ground along the rail road line were studied. The main contents are as follows.(1) In order to evaluate the effect of each parameter on the ground response and its propagation features induced by moving trains, an extensive parametric study was conducted. The influences of several controlling parameters, including track stiffness, embankment height, shear wave velocity and damping ratio of underlying ground soil, train speed and its vibration frequency were clarified.(2) Investigated and compared the effectiveness of three different vibration isolation measures, i.e., open trench, in-filled trench, and elastic foundation. Both the dynamic responses of threes-dimensional ground with vibration isolation measure and without were obtained. Concerning the effect of isolation in different cases, the geometric and material parameters of the three vibration isolation measures were investigated include the distance to track center, depth, width and thickness, damping radio, shear wave velocity, etc.(3) Analyzed the characteristic of dynamic stresses and stress paths of soil element beneath railway embankment during passages of train moving loads. The influences of train speed and shear wave velocity of soil were studied.The results in this thesis may have reference value for the prediction of train-induced environmental vibrations and for the research of dynamic response of ground Field and vibration isolation.