地铁列车激励下岩石场地振动传递特性测试分析

Test Analysis of Qingdao Rock Site Vibration Transmission Characteristics under Metro Train Excitations

为分析地铁列车运行引起岩石场地振动传递特性,选取青岛某地铁线路区间,对正常运营的地铁引起隧道及地面垂向振动进行同步测试分析。结果表明:1)隧道与地面振动主要集中在50~200 Hz,隧道200 Hz处的振动最为显著,地面60~80 Hz的振动最为显著。地面距离隧道中心线90 m范围内,振动呈波动衰减,在距离隧道中心线30 m与75 m处,存在2个振动放大区,相对于其前一测点,均在8~25 Hz与60~80 Hz频段有所放大;2)隧道壁至地面振动传递损失曲线均近似呈V型分布,高频段振动传递损失较低频段大,传递损失基本在20~25 Hz附近最小,大部分测点在此频段传递损失出现负值,说明此频段附近振动加速度从隧道壁传递至地面有放大现象;3)地铁列车运行引起青岛岩石场地振动传递特性与其他场地类别相比有相似性也有差异性,测试结果可为青岛地铁后期线路规划对地面环境振动影响提供参考。

To analyze the vibration transmission characteristics of rock sites, induced by the passage of metro trains, in situ synchronous tests of the vertical vibration of the tunnel and the ground were carried out in one section of the Qingdao metro line. The results show the following： 1） The vibration frequencies of the tunnel and the ground are mainly 50–200 Hz, with the most remarkable frequencies being 200 Hz and in the range of 60–80 Hz for the tunnel and the ground, respectively. The vibration attenuates with fluctuations in the range of 90 m from the tunnel center line, whereas there are two vibration amplification regions at distances of 30 m and 75 m from the tunnel center line, both in the 8–25 Hz and the 60–80 Hz range, which are amplified compared to their previous measuring points. 2） The vibration transmission loss curves from the tunnel wall to the ground all exhibit approximately V-shaped distribution, and the transmission losses at high frequencies are greater than those at low frequencies. The minimum transmission losses are close to the 20–25 Hz range, and most of the measuring points are negative at this frequency band, which indicates that the vibrations from the tunnel wall to the ground are amplified. 3） There are similarities and differences in the vibration transmission characteristics between the Qingdao rock site and other site types. The test results can provide a reference regarding the influence of environmental vibration induced by the Qingdao metro transit.