地铁隧道上盖建筑振动特性分析

Analysis of Metro Tunnel Overhead Building Vibration Characteristics

[目的]近年来,地铁隧道沿线上盖物业开发迅速,其在充分利用了城市空间的同时,地铁列车运行引起的振动也将对其产生显著的影响。由于上盖物业结构形式复杂,列车振动在上盖建筑中的传播规律尚不明确,故有必要开展相关研究。[方法]依托宁波市轨道交通与区块开发共建综合体工程,建立了列车-隧道-土体-上盖建筑的三维振动有限元模型;通过仿真实验,分析了隧道埋深、隧道距上盖建筑水平间距及建筑物楼层对振动传播的影响。[结果及结论]①当上盖建筑与振源的水平间距位于一定范围之内,随着水平间距的增大,Z振级单值出现增长;当超出该范围后,Z振级单值随水平间距的增大发生了较为明显的衰减;②上盖建筑振动在不同建筑层数下的竖向传播规律在总体上具有一致性,在底部楼层中,振动会先达到一个最大值,而后随着楼层的增加而减小,最后在顶部楼层呈现放大的趋势;③通过1/3倍频程可以发现,上盖建筑振动传播过程中,不同隧道埋深、不同水平距离及不同建筑层数下的同一楼层中心频率振动加速度级分布的趋势相似,其Z振级结果的差异主要是在主频段的衰减幅度,即振动传播过程中衰减的是主频段的振动,不改变主频的分布范围。

[Objective]In recent years,overhead properties along metro tunnel lines are rapidly developing,making effective use of urban space.However,vibrations caused by metro train operation significantly affect these properties.Due to the complexity of overhead building structures and unclear propagation laws of train vibrations in these buildings,it is necessary to conduct relevant research.[Method]Based on Ningbo an integrated projected by rail transit and block development,a three-dimensional vibration finite element model of train-tunnel-soil-overhead building is established.Through simulation experiments,the impact of tunnel depth,horizontal distance between the tunnel and overhead buildings,and the number of building floors on vibration propagation is analyzed.[Result&Conclusion](1)When the horizontal distance between overhead buildings and vibration sources is within a certain range,the Z vibration level increases with increasing horizontal distance.Once exceeding this range,the Z vibration level decreases significantly with increasing horizontal distance.(2)The vertical propagation law of overhead building vibrations under different numbers of building floors generally shows consistency.On the lower floors,vibrations reach a maximum value first,then decrease with increasing floors,and finally show an amplification trend at the top floors.(3)Through 1/3 octave band analysis,it is observed that during the propagation of overhead building vibrations,the trends of vibration acceleration level distribution at the center frequency of the same floor are similar for different tunnel depths,horizontal distances,and building floors.The main difference lies in the attenuation magnitude in the main frequency band,indicating that the vibrations attenuate in the Z-level frequency mainly band during propagation without altering the distribution range of the main frequency.