Based on train-bridge coupling dynamics and wave motion theories in engineering,three-dimensional finite-element analysis was used to analyze the dynamic characteristics of ground and building vibrations induced by passing trains on bridge structures.The finite-element mesh included moving trains,bridge superstructures,bridge foundations,soil and nearby buildings.A number of finite-element analyses were performed to investigate the propagation of vibration and vibration level in buildings.A wide variety of influence factors were used for this evaluation.The primary influence factors included the vibration source distance,train speed,and soil shear wave velocity.The results indicate as follows:The ground vertical vibration level decreases with increasing distance to vibration source;the ground lateral vibration level increases at first and then decreases similar to the ground vertical vibration;the vibration attenuation at low frequencies is smaller when compared with the attenuation at high frequencies;the predominant frequency of soil shifts to higher frequencies with increasing of train speeds; building vibration levels decrease with increasing of the distance to vibration source,but nonlinearly with the train speed and soil shear wave speed;the lateral vibration level of low buildings is dominated by the first modal shape,but the second and third modal shapes dominate for high-rise buildings.%为研究轨道交通中车-桥系统耦合振动诱发的周围环境及建筑物振动,应用车-桥耦合动力学理论及工程波动理论,建立车桥土-建筑物耦合振动系统整体三维有限元模型.系统分析振动由产生到传播的整个过程,以及振源距离、车速、场地土特性对框架结构房屋振动的影响.研究结果表明:地面横向振级随振源距离的增加先增大后减小,竖向振级则随振源距离的增加而单调减小,二者的衰减均具有一定的波动性；土体振动的高频分量衰减速度大于低频振动的衰减速度,并且远离振源点的振动主要是由低频振动引起；随着车速增加,地面振动主频提高；低层建筑物楼层振级分布以1阶振型为主,高层建筑则以2～3阶振型为主；建筑物振级随振源距离增加而减小,与车速和土层剪切波速的关系并非简单的线性关系.
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