地铁诱发地面振动传播衰减特性分析

Analysis on Propagation Attenuation of Subway-induced Ground Vibrations

对上海地铁线路某区间段的地面振动进行测试,得到上下行多组地铁列车运行时地表不同测点处的振动加速度。统计所测加速度时程记录的峰值和有效值,并对信号进行谱分析。采用不同频率计权曲线对实测地表加速度进行振级计算,并分析新旧曲线对振级计算结果带来的影响。建立二维有限元平面应变模型,模拟地铁运行引起的土层场地地面振动,并与实测地面振动进行对比。实测数据的统计结果表明,地铁诱发地面振动的主要频率范围为40～90Hz之间,地铁列车引起的地面振动在衰减过程中存在放大区,为距地铁中心线15m处前后。振级计算结果表明,与W计权曲线相比,WK计权曲线加重了10～80Hz范围内高频振动对人体的影响,WK计权振级比W计权振级大3.2dB。数值模拟的振动衰减规律和实测一致。

An in-situ measurement was conducted at Shanghai metro interval to study the ground vibrations induced by normal operation of subway.The peak value and root-mean-square value of vertical vibrations were computed and the signal spectrum analysis was done.The vibration level was calculated by two different frequency weighting curves.A 2-D finite element analysis was made to simulate the measurement phenomenon.The measurement results show that there was an amplified zone,the position of which is 15 meters away from the tunnel center.Compared with the W frequency weighting curve,the Wk frequency weighting curve weighs heavier on the influence of the human body in the frequency range from 10 Hz to 80 Hz.The vibration level value is 3.2 dB more than the case using W frequency weighting curve.The simulated phenomena are in agreement with the measurement results.