地铁及地面交通频率对地表环境振动的影响

Frequency effect of metro and traffic induced ground vibrations response

地铁周边地面环境振动的大量实际观测数据分析显示,地面振动大小与源频率成分有关.但是实际振动观测受周围环境振动影响较大,为了从理论上解释地铁以及地面交通源频率成分对地表环境振动的影响,本文通过二维有限元数值模拟来研究1~20 Hz激振源分别作用于地面和地下,以及地下与地面同时加载这三种情况下地面的振动加速度响应.通过与地面实际观测资料对比,得出结论:(1)由于地铁或地面交通与地层的耦合振动,使得存在一个特定的频率,当载荷以该频率输入时地面的振动最大,当载荷频率小于或大于该频率的时候,地面振动减小;(2)本文对应的地层模型情况下,随着距离的增加,当源频率低于5 Hz时,地面振动衰减缓慢,当源频率高于8Hz时,地面振动衰减快;(3)在地层不同位置激发振动,地表的最大反应频率不同.

Based on the ground vibration data around subway,we found that the ground vibration response was related to the frequency of source. However the observation was greatly influenced by ambient vibration environment. In order to explain the frequency effect of metro and traffic on ground vibration theoretically,a 2D finite element model was established to calculate the ground vibration,and 1 ~20 Hz excitation sources were respectively applied to the ground,underground,and both ground and underground. By comparison with the observed data,we got conclusions as follows：（ 1） As the coupling vibration of subway,traffic and strata, there existed a specific frequency which would lead the largest ground vibration;（ 2）Corresponding to the stratigraphic model in this paper,with the increase of the distance away from subway,the attenuation of ground vibration was slow when applied a source which frequency was below 5 Hz. The attenuation was fast when large than 8 Hz;（ 3） The maximum response frequency on surface was different when excite at different locations.