顺层岩体各向异性对隧道地震响应的影响

Influence of Bedding Rock Mass Anisotropy on Tunnel Seismic Response

为研究顺层岩体各向异性对隧道地震响应的影响,考虑顺层岩体的横观各向同性本构关系以及顺层岩体中地震波的偏振特性和相速度变化特点,基于黏弹性边界的时域波动理论,建立二维平面地震波从隧道底部入射的输入方法。以某顺层岩体中高速铁路隧道为工程背景,采用ANSYS软件进行地震响应数值分析,研究平面地震波由隧道底部入射时岩层各向异性强度对隧道地震响应不对称性或非反对称性的影响。结果表明:地震qP波入射时,随岩层各向异性的增强,同一时刻地震响应的不对称性总体上逐渐增大,且服从近似线性关系,但地震响应的内力包络却无明确且统一的规律,视岩层倾角而定;地震qSV波入射时,地震响应的非反对称性随岩层各向异性的变化缺乏统一明确的规律,视岩层倾角而定。

In order to study the influence of bedding rock mass anisotropy on tunnel seismic response,an input method of two-dimensional plane seismic waves incident on the bottom of tunnel was established based on the time-domain wave theory of visco-elastic boundary,considering the transverse isotropic constitutive relation of bedding rock mass as well as the variation characteristics of the polarization and phase velocity of the seismic waves in bedding rock mass.A high speed railway tunnel in a bedding rock mass was used as the engineering background.Numerical analysis was carried out on the seismic response by using ANSYS software to study the influence of the anisotropy strength of rock strata on the seismic response asymmetry or non-antisymmetry of tunnel when the plane seismic waves incident on the bottom of tunnel.Results show that,when the seismic qP wave is incident,with the enhancement of rock anisotropy,the asymmetry of seismic response at the same time increases gradually as a whole and obeys the approximate linear relationship.However,there is no clear and unified law for the internal force envelope of seismic response,depending on the dip angle of rock stratum.When the seismic qSV wave is incident,the non-antisymmetry of seismic response lacks a uniform and definite law with the change of rock anisotropy,depending on the dip angle of rock stratum.