| With its comprehensive advantages such as the high speed, large transport capacity, low energy consumption, light pollution, less occupation of the land, high safety and confort performance, the high-speed railway has been developed rapidly all over the world. But, with the increasing of the trains speed, the corresponding problems like the interaction forces between trains and tracks, the safety and comfort of the running train, the reliability of tracks and subgrades are even more conspicuous and these problems still lack enough theoretical research and engineering practice in China. This thesis briefly reviews the domestic and abroad technical development of the high-speed railway, the history and the current situation of the vehicle-track-subgrade dynamics, on the basis of which, the coupled model of the integral large system is established, and numerical simulation is adopt to analyze the dynamic characteristics of ballast-track/ballastless-track subgrade structure and road-bridge transition section of ballastless-track of high-speed railway, the research work has been accomplished with following achievements:(1)The time-varying vehicle-track-subgrade model of vertical coupled system under secondary suspension is presented. According to the practical instance of train running, the vehicle-track-subgrade system is divided into two subsystems, which are vehicle subsystem and track-subgrade subsystem. The couple of two systems is achieved by displacement compatibility of wheels and rail. With track irregularity as system excitation, using Newmark-βmethod to solve motion eqution, the compute indexes which affect the vehicle comfort and safety are achieved. The model reflects enough the interactions of vehicle for foundation and foundation for vehicle. It provided an analyze basic for better solving system match on track traffic and vehicle.(2) Premising the wheel-track action force which is achieved through vehicle-subgrade coupling modle as the analysis loads, the 3-D dynamic finite analysis model on ballasted track (slab ballastless-track) and subgrade is presented. Considered the connection way between different elements and the material nonlinear of track and subgrade, and applied artificial viscoelastic boundary simulating the infinite boundary of subgrade, the simulation analyze on dynamic response of track-subgrade is realized by the secondary exploitation based on ANSYS. The correctness and validity of model is validated by contrasting with reference data and observed data.(3) Based on the parameters of tack and subgrade for passenger dedicated railway, and with the dynamic analyze model for vehicle-ballasted track-subgrade, the effects of train velocity, track irregularity, rigidity and depth of track bed, rigidity and depth of subgrade surface, rigidity of subgrade and ground on system dynamic response are analyzed. Reference for designing and constructing subgrade of passenger dedicated railway is provided.(4) With the analyze model for slab ballastless track-soil subgrade, and applied the parameters of ballastless track for high-speed railway (passenger dedicated railway), the effects of train velocity, track irregularity, dynamics parameters of slab ballastless track on vehicle , ballastless track and dynamic response of subgrade are analyzed. The reasonable assignment range for parameters of track and subgrade of passenger dedicated railway is proposed.(5) Based on the dynamic analyze model for soil subgrade-rigid foundation transition section, under the condition of fold angle irregularity and cosine type irregularity, the dynamic behavior of bridge-subgrade transition section and its effects on train operation are analyzed. The reasonable proposal is provided for designing and constructing bridge-subgrade transition section in passenger dedicated railway.(6) Based on comprehensive the dissertation, some problems which need more study are presented.
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