软土与岩层地质下地铁隧道振动传递特性分析

Analysis of Subway Vibration Transmission Characteristics in Tunnels in Soft Soil and Rock Geological Conditions

在软土和岩层不同地质条件下采集列车通过时隧道壁及隧道上方地面距隧道中心线水平距离为0、15 m和30 m处的垂向振动,经过Fourier变换和1/3倍频程处理得到振动的频谱特性,分析不同频段振动的传递损失。结果显示,对于软土地质和岩层地质,在传递过程中都存在两个振动峰值;振动从隧道壁传至地面0 m时,软土内高频振动衰减较大,岩层内低频振动衰减较大;在地面传播过程中,对于软土地质,在15 m处出现振动放大现象;在30 m测试距离内,12.5 Hz以下的低频振动在两种地质条件下均衰减较小,在30 m处40 Hz以上的振动在两种地质条件下均衰减较大,此研究结果可为不同地质条件下地铁线路上部建筑减振及地铁线路规划提供参考。

The train passing induced vertical vibration on the tunnel wall and the ground above the tunnel at the horizontal distance of 0 m,15 m and 30 m from the tunnel center line under different geological conditions of soft soil and rock strata is collected.Fourier transform and 1/3 octave processing are used to obtain the spectral characteristics of vibration,and the transmission loss of vibration in different frequency bands is analyzed.The results show that there are two vibration peaks in the transmission process of soft soil geology and rock geology.When the vibration is transmitted from the tunnel wall to the ground vertically,the high frequency vibration attenuates greatly in soft soil geology,while the low frequency vibration attenuates greatly in rock geology.In the process of ground propagation,vibration amplification occurs on the ground at the point with 15 m horizontal offset from the central line of the tunnel in soft soil geology condition.In the test distance of 30 m from the central line,the low frequency vibration below 12.5 Hz attenuates slightly in both geological conditions,and the vibration above 40 Hz attenuates greatly in both geological conditions.The research results have provided a reference for vibration reduction of upper buildings and subway line planning under different geological conditions.