Ⅰ型轨道-路基系统动力荷载放大系数模型试验研究

Experimental study of dynamic load magnification factor for type Ⅰ track-subgrade system

高速列车行车时产生的动力荷载大小受多种因素影响,以列车运行速度的影响尤为关键。由于车辆-轨道-路基结构的复杂性,要通过理论计算准确地确定行车速度对动力荷载的影响并不容易。目前足尺物理模型试验已成为高速铁路无砟轨道路基结构动力性能研究的重要手段。根据沪宁城际无砟轨道设计和施工标准,建成室内1:1无砟轨道路基模型,通过单个轮轴的动态激振试验获得Ⅰ型轨道板动应变幅值及路基动土压力幅值随加载频率的变化规律,在该基础上得到列车动荷载随行车速度的变化规律。结合德国铁路动力荷载放大系数的计算公式,提出确定高速铁路I型轨道结构动力荷载放大系数的方法,并分别获得轨道板与路基结构动力荷载放大系数随列车运行速度的变化规律,可为我国I型轨道-路基系统设计动力荷载的确定提供依据。

There are lots of factors that affect the dynamic load induced by high-speed train; the train speed is one of the most critical factors. It is rather difficult to determine the effect of train speed on dynamic load using theoretical method due to the complexity of vehicle-track-subgrade interaction. Large-scale physical model test has gradually become one of the most popular approaches for studying the dynamic characteristics of ballastless track structure of high-speed railway. A full-scale model of ballastless track subgrade was constructed based on the design and construction standard for high-speed railway line from Shanghai to Nanjing. The dynamic strain of type I slab and dynamic soil pressure of subgrade were obtained by conducting single wheel axel exciting test. The relationship between dynamic load and train speed was presented. The dynamic load magnification factors of slab and subgrade structure under different train speeds are obtained respectively. The magnification factors are of great significance for designing the dynamic load in type I track-subgrade system.