列车荷载对临近地铁结构动力响应分析

The Dynamic Response Analysis of Nearby Existing Line Subway Tunnel under Train Dynamic Loads

以某城际铁路临近既有线盾构段为工程依托,采用人工数定激励函数确定列车动荷载时程曲线,结合Flac 3D计算软件及Drucker-Prager本构模型对临近地铁结构在列车动荷载影响下的动力响应进行分析,根据计算结果可知,列车动荷载会造成管片结构单元以及下部地层位移、应力波动,但是经过铁路正线路基及围岩介质材料消散作用,时程曲线波动频率远远低于列车振动荷载频率变化,列车驶过该盾构段上方之后,竖向位移与应力逐渐恢复至初始水平,此时隧道结构属于应力卸载过程,时程曲线没有明显波动.

Based on the shield section which is nearby the existing line,the time-history curve of the train vibration loads is determined by artificial deterministic activation function.The dynamic response analysis is performed by the numerical software FLAC（superscript 3D）,by which the elastic-perfectly plastic constitutive model and D-P criterion are used.According to the calculated results of dynamic response analysis,the train dynamic loads are found to cause the fluctuation of stress and displacement in segments and soil.Besides,with the dissipation effect by the railway roadbed and surrounding rocks,the fluctuation frequency of the time-history curve is much lower than train dynamic loads.As the train passes through the shield section,the vertical stress and displacement can be gradually returning to the initial level,and the time-history curve has no significant fluctuations due to the unloading process.