地铁运行时轨道-隧道-地层振动实测与分析

以上海地铁9号线某曲线段隧道为背景,通过在隧道内部、周围土层和地表布置加速度度传感器,对地铁运行引起的轨道-隧道-地层整个空间内的振动进行了现场测试。通过统计各测点的加速度平均峰值、加速度振级以及振动主频,分析了地铁振动在整个空间内的传播规律。实测结果表明:隧道内部及近处地层以垂向振动为主,但曲线段的地表水平振动可大于竖向振动;地铁振动从钢轨传至隧道壁时会有大幅衰减,从隧道壁传递到地表正上方时,振级反而有所增大;地铁振动在传播过程中振动主频范围也在不断减少。整体振动测试有助于全面认识地铁振动传播规律,对地铁线路设计、轨道结构减振具有较好的指导意义。

Field Measurement and Analysis of Train-Induced Vibration in the Whole Track-Tunnel-Ground System

Field measurement of train-induced vibration in the whole track-tunnel-ground system is performed for a curvilinear tunnel section of Shanghai Metro line 9 by installing accelerometers in the tunnel, surrounding soil layers and ground surface for the first time. The propagation characteristics of train-induced vibration is analyzed by calculating the averaged acceleration amplitude, acceleration level and dominant frequencies of the measurement points. Measurement results indicate that vertical vibration is dominant in the tunnel (at the near field of tunnel) but the horizontal acceleration can be larger than the vertical when metro train passes a curvilinear tunnel section. Acceleration level significantly decreases from the rail to the tunnel lining while slight increase occurs when train vibration approaches the ground surface. Besides, the dominant frequency also greatly decreases in the propagation.The whole measurement of track tunnel-ground system contributes to knowing the propagation process of train-induced vibration comprehensively, and provides some guidance to the design of metro lines as well as countermeasures for the vibration attenuation of track structure.