黏弹阻尼道床阻尼厚度对隧道及地表振动衰减特性的模拟研究

为探究黏弹阻尼道床阻尼厚度对隧道及地表振动衰减特性的影响,为工程设计提供理论支持。利用ANSYS建立土体-隧道-道床平面有限元模型,分析在5～25 Hz频率荷载的作用下,整体道床和黏弹阻尼道床在隧道结构中的振动响应,并分析这两种道床下地表距离隧道中心线不同距离的振动加速度的衰减特性。结果表明:荷载频率小于10 Hz时,在地表距离隧道中心25 m左右,振动有明显的放大区域;荷载频率为10～20 Hz,振动加速度随道床阻尼层厚度降低,阻尼层越厚振动衰减越明显;随着黏弹阻尼道床阻尼层厚度增加,隧道衬砌底部振动加速度有效值依次降低,隧道壁竖直方向振动衰减更加明显,阻尼层每增加2 mm,振级降低1～4 d B。

Simulation Study on the Effect of Damping Thickness of Viscoelastic Damping Track Bed on Tunnel and Surface Vibration Attenuation Characteristics

This paper investigates the effect of damping thickness of viscoelastic damping track bed on the attenuation characteristics of tunnel and surface vibration,and provides theoretical support for engineering design.The plane finite element model of soil-tunnel-track bed is established by using ANSYS.The vibration response of the monolithic track and viscoelastic damping track in the tunnel structure under the frequency load of 5～25 Hz is analyzed,and the attenuation characteristics of the vibration acceleration at different distances from the tunnel centerline under the two tracks are analyzed.The results show that when the load frequency is less than 10 Hz and the surface of the tunnel is about 25 m away from the center of the tunnel,the vibration extends obviously to enlarged area.At the loading frequency of 10～20 Hz,the vibration acceleration decreases with the thickness of the bed damping layer,and the thicker the damping layer,the more obvious attenuation of vibration.As the thickness of the damping layer of the viscoelastic damping bed increases,the effective value of the vibration acceleration of the bottom of the tunnel lining decreases,and the vibration attenuation in the vertical direction of the tunnel wall becomes more obvious.For each 2 mm increase of the damping layer,the vibration level is reduced by 1～4 dB.