列车移动荷载下高速铁路板式轨道路基动力性态的全比尺物理模型试验

列车移动荷载下高速铁路板式轨道路基的振动特性和动力荷载传递规律对高速铁路的设计和运行维护十分重要。介绍了一种全比尺的高速铁路板式轨道路基模型和可模拟真实列车荷载高速移动的分布式加载系统,最高模拟列车速度可达360 km/h。基于该模型试验平台,对中国高速列车以不同速度运行下板式轨道路基的振动和动应力特性进行了试验研究。结果表明轨道结构的振动随着车速的提高近似呈线性增加的趋势；路基结构的振动存在阶段性,列车速度低于180 km/h时振动速度增长缓慢,而后随着速度的增加迅速增大；基床表层的碎石层对振动在路基中的传播有很好的吸收作用。试验发现,尽管无砟轨道路基表面的动应力水平远低于有砟轨道,但无砟轨道路基动应力沿深度的衰减速度要缓于有砟轨道。试验进一步发现,无砟轨道路基动应力的增长模式与列车速度和土体所处深度均有关,基于试验结果提出了用于预测高速铁路路基动应力的经验表达式。

Full-scale model tests on dynamic performances of ballastless high-speed railways under moving train loads

The dynamic performances of ballastless high-speed railways under moving train loads, such as vibration behaviors and dynamic soil stresses, are two important issues in the design and maintenance of high-speed railways. Based on an established full-scale physical model for slab tracks, a distributed loading system consisting of eight high-performance hydraulic actuators is developed to simulate the moving train loads with the highest speed of 360 km/h. The tests results such as vibration velocity and dynamic soil stress are offered for a better understanding of dynamic behaviors of slab tracks at various train speeds. The vibration velocity of track structure exhibits an approximately linear tendency with the train speed, while it begins to grow faster until the train speed reaches 180 km/h. The roadbed acts as a nice damping layer for vibration reduction. Although the dynamic soil stress at roadbed surface is much lower in ballastless tracks than that in ballasted tracks, it decreases much slowly with the soil depth in ballastless tracks. Meanwhile, the dynamic amplification coefficient of soil stress is found to be related to both the train speed and the soil depth. An improved empirical formula is then proposed to determine the dynamic soil stress of ballastless high-speed railways.