某城市地铁沿线填充屏障的隔振预测

Isolation prediction of environmental vibration base on in-filled barrier along a city metro

建立适合某城市地铁参数的车轨垂向耦合数值模型以获得振源加速度,通过适合某城市典型场地条件的隧道-土体有限元模型,在振源与控制区间设置不同参数的填充屏障对隔振效果进行预测分析。结果表明:波阻抗比为填充材料影响的主要因素,当波阻抗比越靠近1,隔振效果越差;针对该城市典型场地条件,刚性填充屏障的有效隔振频段为10~20 Hz,而柔性填充材料的有效隔振频段为40 Hz以上,且在25~40 Hz间除个别频率点外也有较好的隔振效果;6 m内填充屏障的深度增加,隔振效果显著增大,而填充屏障的宽度却无明显影响;刚性填充屏障与振源的设置距离宜大于振源埋深,只适合被动隔振,柔性填充屏障更适合主动隔振。

In a city,a vehicle-track coupled model of vertical vibration was established for metro acceleration,and a tunnel-soil model of 3D FEM was established base on the typical site along this city metro lines.Through the application of the metro accelerations and tunnel-soil model,the environmental isolation effects between vibration resource and control points were predicted with in-filled barriers of influential parameters.The results showed that the wave impedance ratio of infilling was the main factor of isolation effect,and the environmental isolation effect was worse when the closer this value was reached to 1.According to the typical site conditions and soil characteristics of this city,the effective frequency bands of rigid-filled and flexible-filled barriers were 10-20 Hz and more than 40 Hz respectively,and the frequency bands about 25-40 Hz of flexible-filled barriers also was achieved a good isolation performance except at individual point.It was observed that the barrier depth has an important effect on isolation effect within 6 m,deeper the barrier was,the better isolation effect retains,but the width of barrier has not statistically significant impact on isolation effect.Rigid-filled barriers were only suitable for passive isolation which the horizontal distance between vibration resource and barrier should be more than the depth of vibration source,and flexible-filled barriers were more adaptable to active isolation.