地铁车辆段路基对列车振动响应数值模拟分析

Numerical Simulation Analysis of the Dynamic Loads Distribution in Subgrade of Metro Depots

为研究车辆段不同轨道型式、不同基床结构下路基对列车的振动响应特性,依托郑州地铁铁炉西车辆段工程,开展不同路基结构条件下的动荷载数值模拟分析,研究路基动荷载分布随路基结构的变化规律。结果表明:无砟轨道在列车相同速度下产生的动荷载值小于有砟轨道;基床表层厚度增加对于减小列车行驶产生的动荷载效果更加明显,但过厚的基床会提高路基刚度,不利于应力消散,因此基床厚度加到一定程度后,减小动荷载的作用逐渐不明显。数值模拟结果表明:地铁车辆段路基基床表层、底层厚度设计方案可在“0.3 m+0.9 m”和“0.4 m+0.7 m”的基础上分区,合理制定,以基底动静应力比小于0.2为准,以期道床结构安全、经济、合理。

The design standards for the roadbed structure of the metro depot have not been clearly defined in the Metro design specification(2013),and the current practice of using the main line standard results in high and unreasonable costs.This study relies on the Zhengzhou Metro Tieluxi Depot project to conduct a numerical simulation analysis of dynamic loads under different subgrade structures and to study the variation law of the dynamic load distribution.The dynamic load generated by the ballastless track at the same train speed was smaller than that generated by the ballasted track.An increase in the thickness of the subgrade surface layer has a more substantial impact on reducing the dynamic load generated by the train operation.However,an excessively thick foundation increases roadbed stiffness,which is not conducive to stress dissipation.Hence,when the foundation thickness increases to a certain extent,the effect of reducing the dynamic loads gradually becomes less significant.The numerical simulation results show that the design scheme of the metro depot subgrade can appropriately adjust the parameters on the basis of"0.3 m+0.9 m"and"0.4 m+0.7 m",ensuring that the dynamic and static stress ratio of the subgrade is strictly less than 0.2,attaining the best level of safety and economy.