轨枕空吊对桥上有砟轨道结构动力响应的影响
Effects of unsupported sleepers on dynamic response of ballast track structures on bridge

摘要 基于车辆-轨道耦合动力学理论，将轨枕下部的有砟轨道考虑为弹簧-阻尼系统，假设该弹簧-阻尼系统失效来模拟轨枕空吊状态，建立含轨枕空吊的有砟轨道-桥梁耦合模型.采用Newmark直接积分法求解车辆-轨道-桥梁耦合动力学方程，计算列车通过时轨枕正常状态和空吊状态下轨道结构的位移和加速度，同时对空吊轨枕出现的数量及纵向分布位置对轨道结构动力特性的影响进行分析.对轨枕无空吊状态、单根空吊状态、连续2根空吊和间隔2根轨枕空吊4种工况下轨道结构的动力响应进行分析.研究结果表明：连续2根轨枕空吊影响下轨道响应显著大于其他3种工况，间隔2根轨枕空吊的影响略大于单根轨枕空吊的影响，但差别较小；轨枕空吊对有砟轨道结构动力影响范围沿轨道纵向不超过2跨轨枕间距；随着列车运行速度的增加，轨枕空吊影响下轨道结构位移变化较小，加速度则明显加大，基本呈线性增长.
Abstract：Based on the vehicle-track coupling dynamics theory, a coupling model of ballast track with unsupported sleepers is established, in which the ballast track under sleepers is considered as a spring-damping system, and the cases of unsupported sleepers are simulated by supposing that the spring-damping system is invalidated. The Newmark direct integration method is used to solve the vehicle-track-bridge coupling dynamic equation in order to calculate displacement and acceleration of the track structures with normal sleeper and unsupported sleeper.At the same time, the influence of the number and the distribution of unsupported sleepers in longitudinal direction on track structure is analyzed. Dynamic responses of track structures are anlyzed in cases of normal sleeper, single unsupported sleeper, two continuous unsupported sleepers and two interval unsupported sleepers. The results show that the track response of two continuous unsupported sleepers is significantly greater than that of the other two conditions. The track response of two interval unsupported sleepers is slightly greater than that of the single unsupported sleeper, but the difference is small. The effect range of unsupported sleeper on the structure of ballast track is no longer than the distance of two span sleepers along the track longitudinally. With the increase of train speed, the displacement of track structure under the influence of sleeper changes little, but the acceleration increases obviously, showing linear growth.