地铁移动荷载作用下准饱和地基振动特性及隔振研究

Study on vibration characteristics and vibration isolation of nearly saturated ground under moving load of subway

根据2.5维有限元理论,将地基假设为准饱和地基,建立地铁列车-轨道-隧道衬砌-分层准饱和地基2.5维有限元模型,研究准饱和地基饱和度变化对地铁列车运行产生的地面振动响应的影响规律,并分析了准饱和地基饱和度对波阻板隔振性能的影响。结果表明:准饱和地基饱和度减小使地面振动加速度、水平x方向、竖向z方向位移幅值有一定程度减小;随着距离轨道中心距离增加,饱和度对地面振动响应的影响越明显;准饱和地基饱和度减小,波阻板对x方向隔振性能增强,对z方向隔振系数减弱;波阻板对地铁移动荷载产生的低频振动有较好隔振性能。

According to the 2.5-dimensional finite element theory,the foundation was assumed to be a nearly saturated foundation and a 2.5-dimensional finite element model of subway train-track-tunnel lining-layered nearly saturated foundation was established.The influence of changes in saturation of the nearly saturated foundation on the ground vibration response generated by subway train operation was studied,and the influence of the saturation of the nearly saturated foundation on the vibration isolation performance of wave impedance block(WIB)were analyzed.The results show that the decrease of saturation of the nearly saturated foundation reduces the ground vibration acceleration and the displacement amplitudes in horizontal x direction and vertical z direction to a certain extent.With the increase of the distance from the track center,the influence of saturation on the ground vibration response becomes more obvious.When the saturation of the nearly saturated foundation decreases,the vibration isolation performance of WIB in x direction is enhanced whereas the vibration isolation coefficient of WIB in z direction is weakened.WIB has better vibration isolation performance for the low-frequency vibration caused by the moving load of the subway.