论文部分内容阅读
盆山耦合地形作为一种常见的复杂场地,其对地震动的复合影响目前尚未得到清晰认知。为此,引进一种高精度的有限元-间接边界积分方程耦合方法(FEM-IBIEM),探讨沉积盆地及其邻近山体对地震波(平面P波、SV波和Rayleigh波)的多次散射作用。数值结果表明:沉积盆地及其邻近山体存在显著的动力相互作用,整体位移响应特征依赖于山体、盆地的空间位置和几何特征,入射地震波的频率和角度等因素;整体上看,P波垂直入射下,较高山体的存在对沉积盆地内部位移具有明显的放大效应;SV波入射下,山体的影响相对较小,且盆地内部不同位置可能会表现出完全不同的放大或缩小特征;Rayleigh波从山体一侧入射时,山体对沉积盆地存在明显的“屏障”作用,而从盆地一侧入射时,在低频段山体反而会表现出放大作用;总体上看较高山体对沉积盆地的影响程度更为显著。鉴于山体的存在显著改变了沉积盆地的位移幅值和频谱特性,实际盆地的地震动确定需考虑邻近山体的影响。
Basin-mountain coupled terrain as a common complex site, its complex impact on the earthquake has not yet been clearly recognized. For this reason, a high-precision finite element-indirect boundary integral equation coupled method (FEM-IBIEM) is introduced to investigate the multiple scattering of seismic waves (plane P wave, SV wave and Rayleigh wave) in the sedimentary basin and its adjacent mountains. The numerical results show that there are significant dynamic interactions between the sedimentary basin and its adjacent mountains. The overall displacement response depends on factors such as the spatial and geometrical characteristics of the mountain and basin, the frequency and angle of incident seismic waves, etc. On the whole, Under the condition of SV wave incident, the influence of the mountain body is relatively small, and different positions inside the basin may show completely different enlargement or shrinkage characteristics; Rayleigh wave from At the side of mountain, there is a clear “barrier” effect on the sedimentary basin. However, when it is incident on the side of the basin, the mountain body in the low frequency band will instead show a magnifying effect; on the whole, the influence of the higher mountains on the sedimentary basin The degree is more significant. In view of the fact that the existence of the mountain body significantly changed the displacement amplitude and spectral characteristics of the sedimentary basin, the determination of the actual basin need to consider the influence of the neighboring mountains.