地铁隧道整体道床不同程度离缝对轨道结构动态响应影响分析

Analysis of Dynamic Response of Track Structure Affected by Different Degrees of Separation of the Monolithic Track Bed in Subway Tunnels

地铁隧道整体道床结构普遍存在离缝病害,对列车安全运行影响较大。为了分析不同程度离缝对轨道结构动态特性的影响,文章建立钢轨-道床-隧道有限元仿真模型,基于对地铁整体道床离缝病害调研结果,设置不同离缝病害程度的道床结构,计算不同工况下钢轨和道床的动态响应。研究结果表明:(1)道床离缝病害在地铁运营初期已普遍存在,离缝主要分布于伸缩缝附近,且在道床横向两侧同时出现;(2)离缝程度较小时,其宽度远大于道床位移幅值,轨道结构的动力响应几乎不受宽度变化的影响;(3)在离缝未贯通道床底面时,钢轨和道床的垂向位移增加量有限,离缝完全贯通会导致道床的承载能力显著降低,钢轨和道床的垂向位移与离缝长度呈正相关关系;(4)道床离缝会引起轨道结构振动不同程度地加剧,其中结构振动受深度的变化较为敏感。

The monolithic track bed structure of subway tunnels generally suffers from the separation defect,threating the safe running of the train.In order to analyze the influence of different degrees of separation defects on the dynamic characteristics of the track structure,a finite element simulation model of rail-track bed-tunnel is established in this paper.Based on the investigation results of the separation defects of the monolithic track bed in a subway,the track bed structure with different degrees of separation defects is set up,and the dynamic responses of the rail and track bed under different working conditions are calculated.The conclusions are as follows:1)Track bed separation defects have occurred in the early stage of subway operation.The separation defects mainly distribute near the expansion joints,and on both ends of the track bed;2)When the degree of separation is small,the width of the separation is far greater than the displacement amplitude of the track bed,and so the dynamic response of the track structure is hardly affected by changes of the separation width;3)When the bottom surface of the track bed is not penetrated through by the separation,the vertical displacement increment of the rail and the track bed is limited.However the load-bearing capacity of the track bed will be significantly reduced when the separation is completely through the track bed.The vertical displacements of the rail and track bed have a positive correlation with the length of separation;4)The track structure vibration will be intensified in varying degrees due to separation of the track bed,and the structural vibration is more sensitive to the change of separation depth.