Vehicle-track-bridge System Dynamic Analysis Model and Track Irregularities Control on Quasi & High-speed Railway (An Abstract of the Ph.D.Thesis)

China railway, as the essential infrastructure of China national economy, has to face and solve a lot of technical problems so as to cope with the strategic requirement of continuous, rapid and healthy development of national economy. The main issue is to raise passenger train speed and develop high-speed train operation technology. It involves such fields as locomotive and cars, signaling and communication, traffic organization, railway construction etc., it is a huge and complicated system engineering. In the system, railway track, bridge and tunnel are the running foundation of rapid and high-speed train, their quality directly affect the train speed and running quality, such as running stability, comfort and safety. So it is necessary to study the influence of track irregularity on train running quality and take effective measure to control track irregularity during the development of high-speed passenger train operation technology, for ensuring train running safety, extending the service-life of track and vehicle parts and improving train running stability and comfort. In view of the above-mentioned facts, the influence on running safety and stability of quasi high-speed passenger car under track irregularity excitation is the topic of the thesis. Taking vehicle-track or vehicle-track-bridge vertical and lateral coupling system dynamic model as analytical method, the thesis systematically discusses dynamic behavior of quasi high-speed vehicles excited by track irregularities of the ballast track, the influence on dynamic response of rail/wheel system excited by rail surface vertical short-wave roughness, serviceability of running vehicles on bridge under excitation of special track irregularities caused by bridge arch, pier uneven settlement and subsidence error between abutment and subgrade. Track irregularities are actually complicated random processes, consisting of approximately stationary ergodic processes of general track irregularities in entire length and non-stationary processes reflecting geometric state of the local deflects in track. The thesis describes the characteristics of track irregularities in two ways, the characteristics of track local irregularity is expressed with such value as peak, peak-peak, amplitude variety rate and wavelength, half-wavelength, cycle, etc, stationary and ergodic irregularities described by PSD and amplitude statistic parameters. Considering the needs of vehicle-track dynamic model input, track local irregularities are described as mathematical functions, such as cosine, sinusoidal, exponent function, random track irregularity simulate from PSD by use of second filter method. Based on rail/wheel reaction and track/bridge reaction theory and system engineering theory, new vehicle-track and vehicle-track-bridge system dynamic models of vertical and lateral coupling system are established and discussed in details, including the models for ballast, ballastless track and simple supporting bridge. The characteristics of the models are: (1) vehicle-track and vehicle-track-bridge system dynamic models are coupled in vertical and lateral; (2) track vibration on bridge is fully taken into account, track on bridge is considered as one or two layer continuous-point supported rail model, according to actual track structure, interaction between vehicle and bridge is transfered from track structure; (3) three types of ballastless track models (tie-embedding, elastic-tie-block, slab track) are presented; (4) the models reflect the main feature of actual vehicle, track and bridge structure in detail, the response computation frequency of models is wide, which can be applied to analyze both low frequency and high frequency vibration. Considering differential characteristics of vehicle-track and vehicle-track-bridge system equations (time-variation coefficient matrix and moving train load), the thesis divides the whole system into three subsystems (vehicle, track and bridge) which are coupled by rail/wheel forces and track/bridge forces, proposes a new numerical computation metho