基于现场测试的曲线段地铁地面振动传播规律

在地铁区间为小半径曲线、地面无干扰振源并可以布置高密度测点的珍贵测试条件下,采用高灵敏度数据采集与分析系统,对北京地铁某曲线段进行地面振动测试。根据测试数据,研究地铁列车通过曲线段时引起地面振动加速度的时域和频域内传播规律。结果表明:在距离隧道中心线100m范围之内,地铁运营引起地面振动加速度的时程峰值主要在10-2 m·s-2量级,远大于背景振动下的10-4 m·s-2量级;在距离隧道中心线50m范围之内,水平振动强度是竖向振动强度的2～4倍,建议在涉及曲线段地铁的环评中应同时考虑竖向振动和水平振动的影响;水平振动加速度的主要频率成分为30～120Hz,建议在关于曲线段地铁的试验、测试和模拟中应选取较宽的频率分析范围;地面振动加速度频谱幅值随着与隧道中心线间距离的增加而呈波动性衰减。

Propagation Law of Ground Vibration in the Curve Section of Metro Based on In-Situ Measurement

Taking advantage of such precious test conditions as small radius curve,no interference vibration source from ground and high density measuring points,the ground vibration measurement on top of a curve section of Beijing Metro was conducted by high sensitivity data collection and analysis system.On the basis of test data,the propagation laws of ground vibration acceleration induced by metro train passing the curve section were investigated in the domains of time and frequency.Results indicate that in the range of 100 m from tunnel center line,the time history peak value of ground vibration acceleration induced by metro operation is mainly in 10-2 m·s-2 order of magnitude,which is much larger than 10-4 m·s-2 order of magnitude under background vibration.The horizontal vibration is 2 to 4 times of the vertical vibration in the range of 50 m from tunnel center line.It is suggested that both the vertical and horizontal vibration should be simultaneously taken into account in the environmental assessment related to the curve section of metro.The main frequency components of horizontal vibration acceleration are 30 to 120 Hz.It is recommended that broader frequency analysis range should be selected in the tests and simulations concerning the curve section of metro.The spectrum amplitudes of ground vibration acceleration attenuate in the form of fluctuation with the increase of the distance from tunnel center line.