双线地铁隧道对三维非线性场地地表地震反应的影响

Effect of Double Line Subway Tunnel on Ground Seismic Response of Three-dimensional Nonlinear Field

地铁隧道的存在破坏了原有场地的完整性,进而在地震来临时影响场地的地震反应。为探讨双线地铁隧道建成后对场地地表水平地震动的影响,针对北京某一典型双线地铁隧道工程场地,建立三维非线性场地模型。采用自由场边界和应力时程地震波输入方式,运用有限差分数值分析软件FLAC^(3D)进行模型计算,分析了双线地铁隧道对三维非线性场地地表地震反应的影响。结果表明:1双线地铁隧道的存在使隧道附近场地地表地震动峰值加速度呈现先增大后减小并趋于自由场的趋势;2双线地铁隧道的存在主要影响场地加速度反应谱的短周期部分;3入射地震动频谱对双线地铁隧道的场地地震反应有着显著的影响。文中得出的影响规律,为双线地铁隧道附近场地的设计地震动参数确定提供参考依据。

The existence of the subway tunnel destroys the integrity of the original site,and then affects the seismic response of the site when the earthquake strikes. In order to investigate the influence of the construction of double line subway tunnel on ground vibration seismic response,in view of a typical double line subway tunnel site in Beijing,with a three-dimensional nonlinear field model being established,the finite difference numerical analysis software FLAC^(3D) is used to analysis the effect of double line subway tunnel on ground seismic response of threedimensional nonlinear field,free field boundary condition and stress time history input method of seismic wave being used. It is shown that the existence of the double line subway tunnel makes the peak acceleration of ground motion near the tunnel first increase and then decrease and tend to the free field. In addition,the existence of double track subway tunnel affects the short period of acceleration response spectrum. The spectral characteristics of the incident seismic wave has a significant impact on the site seismic response of the double line subway tunnel. The preliminary results obtained can provide a reference for the design ground motion parameters of the ground near the double line subway tunnel.