地铁隧道洞壁振动时频特性分析

源强的合理确定是地铁环境振动预测及振动控制措施设计的关键因素。采用已通车线路的实测数据作为源强取值的参考是常用做法,但鉴于地铁振动的随机特征及各种线路的差异性,实测源强的统计学结果更具参考价值。基于国内某地铁隧道洞壁多次连续过车加速度时程数据,得出了具有统计学意义的洞壁振动时频特性:振动峰值加速度均值约2.5 m/s^2,强振持时约5.8 s,平均最大Z振级为64.7 dB;洞壁振动主要集中在中高频段,但高频振动经土层传播后迅速衰减而对结构反应影响小。振动加速度反应谱均值、峰值加速度均值、持时均值及振动波形包络参数均可用于人工合成具有统计意义的源强振动加速度时程。

Analysis of Time-frequency Characteristics for Subway Tunnel Wall Vibration

Reasonable vibration source strength is a key factor in the prediction of subway environmental vibration and the design of vibration control method.The common practices use the measured data from the operation subway lines as the reference of source strength value.However,because of the random characteristics of subway tunnel vibration and the difference of various subway lines,the statistical results of measured vibration data prove to have more reference value.By analyzing the acceleration data measured in a subway tunnel where trains continuously passing for many times,the time-frequency statistical characteristics of the tunnel wall vibration are obtained.The peak acceleration is about 2.5 m/s^2 with the duration of 5.8 s,and the average maximum Z VL(vibration level)is about 64.7 dB.The frequency of the tunnel vibration is mainly concentrated in the medium and high frequency bands,but it attenuates quickly in the soil and has less impact on the structural response.The acceleration response spectrum,peak acceleration,duration of strong vibration and waveform parameters can be used in synthesize vibration acceleration time history with statistical significance.