针对我国铁路列车提速后线路结构所出现的突出动力学问题, 基于现代车辆-轨道耦合动力学理论分析结果, 综合提出了强化提速线路的五项关键配套技术对策；通过线路现场试验、工程实践及实际运营观测, 检验了所提技术措施的实际运用效果和现实可行性。提速线路强化配套技术措施的逐步实施, 是确保中国铁路提速线路长期、安全、可靠运营并保持低维修成本的根本前提, 具有深远意义。

列车提速是我国铁路实施的具有战略意义的重大决策。由于提速是在既有线上进行的，提速后机车车辆对线路结构的动力影响将不可避免地增强，给轨道结构强度和线路日常养护维修工作带来不利影响。文中运用车辆-轨道耦合动力学理论，对提速线路上较为突出的几个动力问题--提速道岔、钢轨焊缝、路桥连接处的动力问题，以及车轮擦伤对线路的动力影响等，进行了较细致的分析研究，在此基础上提出了解决这些问题的基本对策。

分析比较了目前国际上常用的车辆脱轨评价标准的特点及其不足, 指出我国现行国家标准GB 5599-85评判车辆脱轨所存在的突出问题, 在此基础上提出直接根据车轮抬升量评判脱轨的原理与方法。运用车辆-轨道耦合动力学理论, 对单轮对爬轨脱轨和跳轨脱轨过程进行了计算仿真, 得出脱轨系数超限时间与车轮抬升量之间的关系, 提出最大允许超限时间为35 m s的安全准则, 并进行了实际线路工况下整车轮轨相互作用脱轨仿真验证。最后提出针对我国车辆脱轨评判的建议标准及其实施细则。

车辆—轨道耦合动力学是在传统的车辆动力学和轨道动力学基础上发展起来的一个新的学科领域，近10年来发展迅速，并取得重要进展，已形成独特的理论体系。本文首先简要回顾了车辆—轨道耦合动力学的研究历史，并对国内外研究进展作了概要介绍；在此基础上着重介绍了作者及其课题组近期开展的研究工作及主要研究结果，包括理论模型、计算机仿真、试验验证、参数确定及应用实践等方面的具体进展；最后指出了机车车辆与轨道系统动力学领域今后拟进一步研究的问题。

介绍了车辆-轨道耦合动力学理论在新型机车车辆研制中的最新应用情况，包括在200km/h“天梭号”高速机车设计、170km/h SS7E型提速客运电力机车改进设计，以及120km/h提速货运电力机车研制中的应用实践。文章着重从提高高速机车蛇行运动稳定性、改进SS7E型客运机车横向动力性能以及降低提速货运机车轮轨动力作用等方面进行了详细论述。结果表明，车辆轨道耦合动力学理论在现代铁路机车车辆研制中取得了显著成效,具有广阔的应用前景。

The vibration of railwayballa st is a keyfact or to cause track geometrych ange and increase of track maintenance costs. So far the methods for analyzing and testing the vibration of the granular ballast have not been well formed. In this paper, a five-parameter model for analysis of the ballast vibration is established based upon the hypothesis that the load-transmission from a sleeper to the ballast approximatelyco incides with the cone distribution. The concepts of shear stiffness and shear damping of the ballast are introduced in the model in order to consider the continuityof the interlocking ballast granules. A full-scale field experiment is carried out to measure the ballast acceleration excited bymoving trains. Theoretical simulation results agree well with the measured results. Hence the proposed ballast vibration model has been validated.

Train derailment is an important factor to influence train-running safety. In recent 10 years, derailment accounts for about 70% of railway heavy and major accidents in China. Because of the complexity of derailment and difficulty of its study, the causes of derailment are usually difficult to be found out. The traditional analytical methods are simplified, which are not able to consider the mutual influence of the factors and therefore cannot explain the essence of derailment. In this paper, a new method, intelligent synthesis is employed to analyze the essential reasons of derail accidents. Some new techniques of artificial intelligence are applied in the analysis of derailment, such as compute intelligence, fuzzy logic, etc. A basic structure of the intelligent derailment analysis support system is established, and a knowledge-ware for analyzing derailment is designed. Finally an example of actual derailment accident is analyzed by using the expert system based on the fuzzy logic method.

A numerical simulation technique is developed to analyse the train-track-bridge system dynamic responses when a train traverses a bridge. The basic idea of the simulation is to consider the train, the track and the bridge as a whole interactive system. The modelling aspect of the train-tack-bridge system is presented. A large-scale software, TTBSIM, is designed to simulate the dynamic responses of the complete train-track-bridge system so as to assess the running safety and the ride comfort of trains traversing bridges in the design stage. Two high-speed running experiments were carried out on the Qinhuangdao-Shenyang line, which were used to validate the TTBSIM technique. Results show good correlation between simulation and measurement. TTBSIM software has provided a dynamic assessment tool for the design of bridges on new high-speed railways.

This paper describes a numerical simulation technique that is used to investigate the dynamic train/track/bridge interaction. Two dynamic models are established to simulate the dynamic responses of a train running on the bridges with the ballasted track and the non-ballasted slab track, respectively. Effect of the track structure and the wheel/rail interaction on the system dynamics is considered in the models. The nfluence of track random irregularities on train/track/bridge dynamic interactions is investigated. The proposed simulation technique is applied to practical construction engineering in the Chinese first special railway line for passenger transport. The structural design of three extraordinary large bridges with non-ballasted tracks in this line is evaluated through a detailed simulation in the design stage and results show that these bridges are able to satisfy the demand of dynamic performance for the high-speed transport.

An interactive model is developed to simulate dynamic behavior of pantograph-catenary systems. Vibrating responses of locomotive roof are directly inputted as excitations to the pantograph, which are obtained with the locomotive-track coupling dynamic model. Effect of locomotive vibrations on pantograph-catenary interactions is investigated for various cases. It is shown that the influence of locomotive vibrations upon the pantograph-catenary system dynamics is not negligible if the track geometric condition is not good, especially in high speed operation.