高速轮轨系统动态脱轨理论及评价方法研究

Train derailment is an important problem which endangers the safety of railway transportation; therefore, studies on the dynamical derailment mechanisms of high-speed wheel/rail systems and the evaluation criteria are of great significance to the running safety of high-speed train. Based on the deep understanding of wheel/rail interaction, a dynamical derailment model of high-speed wheelset-track system will first be developed, in which the transient responses of wheel-rail collision are taken into account together with flexibilities of wheelset and rails, track elasticity and the complicated contact conditions such as multiple-contact, contact lose and Non-Hertzian conformal contact. To reveal the mechanisms of dynamic derailment of high-speed wheel/rail systems, the influences of key factors such as the gyroscopic effects, centrifugal force through curves, flexibilities of axle and wheel web, force conditions, speed, track elasticity, worn profiles and wheel-rail impact will be studied through simulating the dynamical derailment process of high-speed wheelset, i.e. from normal contact to flanging contact till final derailment. New criteria on dynamical derailment will be developed from running conditions and motion based on the dynamic simulations. Finally, the dynamical derailment mechanisms of high-speed wheelset will be applied to the running safety evaluation of Chinese high-speed trains. Influences of vehicle structure, force conditions, parameters variation of suspension systems, high-speed hunting, worn profiles and track conditions on the dynamical derailment of high-speed train will be studied thoroughly, and the assessment method of dynamical derailment and corresponding countermeasures will be proposed accordingly.

脱轨是危及铁路交通安全的重大问题，研究高速轮轨系统动态脱轨理论和评价准则对保障高速列车运行安全意义重大。针对脱轨过程中轮轨间的多点接触、非赫兹型共形接触和接触碰撞等复杂接触现象，本项目以精确的轮轨接触关系为基础，考虑轮轨柔性和轨道结构弹性，建立融合轮轨碰撞瞬态响应的轮对-轨道动态脱轨分析模型。为揭示高速轮轨系统动态脱轨机理，通过数值模拟轮对从正常接触向轮缘接触至最终脱轨的完整动力学过程，以确定高速运行条件关键影响因素（如高速旋转陀螺效应、曲线离心力、轮对柔性、载荷状态、运行速度、轨道弹性、型面服役状态和轮轨碰撞等）的影响规律，并探索从运行条件和运动状态角度提出更准确适用的动态脱轨评价准则。基于上述基础，进一步研究车辆结构、载荷状态、悬挂系统参变、高速蛇行失稳、型面服役状态及线路条件等典型因素对我国高速列车动态脱轨的影响规律，提出相应的评价方法和控制措施。

开展高速轮轨系统动态脱轨机理及评价准则的研究对于保障高速列车运行安全，提高我国高速列车国际竞争力具有重大意义。本项目建立了高速轮对-轨道动态脱轨分析模型，能够考虑轮对和轨道柔性、高速旋转的陀螺效应及离心力、以及轮轨磨耗、三维赫兹滚动接触等复杂接触行为。基于轮对柔性动力学影响研究表明：轮对柔性使得轮轨横向力波动能量增大，弯曲模态对轮轨力的频率敏感特征有诱发车轮周向非均匀磨耗的可能，反对称弯曲模态共振有可能导致高速列车低频蛇行，增大失稳脱轨风险。高速轮对动态脱轨机理研究揭示了不同轮轨冲角、载荷、速度、牵引和制动工况对轮对脱轨的表现形式和影响机理，获得了不同冲角作用下轮对动态脱轨的临界载荷。研究了高速铁路水泥砂浆软化及路基沉降引起的高速列车运行性，脱轨系数和轮重减载率随水泥砂浆软化系数增加而增大，当软化系数超过1000时，脱轨系数和轮重减载率均超标。对车辆蛇行分叉的研究表明，车辆系统存在运动幅值相差不大的两个蛇行运动解并存的现象，在相应速度时会因扰动不同出现车辆摆振，影响行车安全。结合列车轨道动力学模型和汽车碰撞动力学模型，引入基于轮轨几何位置的脱轨评价方法，研究了列车与汽车对向斜碰撞的脱轨机理。其研究表明，列车撞击速度、货车质量、碰撞角度以及碰撞界面摩擦系数对碰撞后列车的运行安全性有重要影响。其中，碰撞货车质量越大，碰撞后的列车越容易脱轨。而轮轨摩擦系数以及悬挂系统参数变化对列车受碰撞后的运行安全性影响较小。此外，基于本研究的推广，对嵌入式轨道上车辆运行安全性、轨道不平顺波长和幅值对车辆动力学的影响也进行研究。本研究对认识高速轮轨系统的脱轨机理，制定合理可靠的评价准则提供了理论基础，同时，理论模型和计算方法对轮轨动力学、磨耗和疲劳损伤的深化研究也具有重要意义。