圆形隧洞对地下地震动的影响:SH波入射

地下结构对地震波的散射改变了场地的动力特性,无论是地上建筑还是地下结构的安全评价和抗震设计中,目前均没有很好的考虑由于地下结构的存在对原场地地震动尤其是地下地震动的影响。基于弹性波动理论,运用波函数展开法和镜像原理,分析了弹性半空间中圆形隧洞对柱面SH波的散射问题,得到了含圆形隧洞的弹性半空间位移解析解。通过数值算例分析了圆形隧洞对原场地地震动的影响,重点考察了隧洞埋深、隧洞半径和围岩衬砌模量比等参数的影响规律。结果表明,地下结构对沿线场地的动力特性有着显著的影响,对其自身以及沿线工程结构的抗震设计提供一定参考价值。

Effect of Circular Tunnels on Earthquake Subground Motions: Incidence of SH Wave

The scattering of seismic waves by underground structures can change the dynamic characteristics of a site. However, the current safety evaluation and seismic design of aboveground and underground structures ignore the influence of underground structures on the ground motion of the original site. The scattering of cylindrical SH waves by a circular tunnel in an elastic half-space is analyzed on the basis of the elastic wave theory by using the wave function expansion method and the mirror image principle, and the analytical solution to displacement in the elastic half-space with a circular tunnel is obtained. The influence of the circular tunnel on the ground motion of the original site is analyzed with numerical examples, and the influence laws of parameters, such as tunnel depth, tunnel radius, and modulus ratio between the lining and surrounding rock, are investigated. Results show that the underground structure drastically affects the dynamic characteristics of the site and can provide some reference value for the seismic design of engineering structures.Keywords:cylindrical SH wave; circular tunnel; scatter; earthquake-resistance of underground structure