高速铁路无砟轨道路基动应力分布特征及解析算法

Distribution Characteristics and Analytical Method of Dynamic Stress on Subgrade of Ballastless Track for High-Speed Railway

通过对京津、武广、京沪、郑万、京沈高铁20多个测试断面进行现场实测、数值仿真及解析分析,得出无砟轨道路基1次加卸载过程由1个转向架的2个轴载叠加作用完成,路基面动应力呈纵向梯形分布、横向均匀分布的特征。提出无砟轨道路基动荷载分配简化模型:将1个转向架的2个轴载视为集中力,并乘以动力系数1.35作为设计动荷载,其传递至支承层或底座板顶面时沿纵向为三角形分布,作用长度3.5 m;沿横向仅在2侧均匀分布、中间0.85 m范围不作用荷载,作用宽度为轨道板宽度。采用Odemark的模量与厚度当量假定对支承层或底座板、基床表层、基床底层进行均一化处理,应用Boussinesq公式计算路基动应力,建立无砟轨道路基动应力解析算法。采用该算法对CRTSⅠ,CRTSⅡ,CRTSⅢ型板式及双块式无砟轨道路基面动应力进行计算,其结果与数值和实测结果基本一致,说明该解析算法是合理的。

Through the field measurement, numerical simulation and analytical analysis of more than 20 test sections of Beijing-Tianjin, Wuhan-Guangzhou, Beijing-Shanghai, Zhengzhou-Wanzhou and Beijing-Shenyang high speed railways, it was concluded that one loading and unloading process of high-speed train load on the ballastless track subgrade was composed of two axle loads of a bogie, and the dynamic stress of subgrade surface presented the characteristics of longitudinal trapezoid and transverse uniform distribution. A simplified model for the dynamic load distribution of ballastless track foundation was proposed, in which two axle loads of one bogie were regarded as concentrated forces multiplied by a dynamic coefficient of 1. 35 as the design dynamic loads.When it was transferred to the top surface of the bearing layer or base plate, the distribution was triangular in the longitudinal direction, with the action range of 3. 5 m. Along the transverse direction, the load was evenly distributed on both sides with no action load in the range of 0. 85 m in the middle, and the action width was the width of track slab. Based on Odemark’s modulus and thickness equivalent assumption, the bearing layer or base plate, the surface layer and bottom layer of subgrade were homogenized. The Boussinesq formula was used to obtain the dynamic stress of the subgrade, and the analytical method for calculating the dynamic stress of ballastless track subgrade was established. Through the proposed method, the dynamic stresses for the subgrades of CRTS I, CRTS Ⅱ, CRTS III slab tracks and double-block ballastless track were calculated. The results were in good agreement with the numerical and measured results, which verified the rationality of the analytical method.