Scattering of SH waves induced by a non-symmetrical V-shaped canyon
Scattering of SH waves induced by a non-symmetrical V-shaped canyon
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DOI：
10.1111/j.1365-246x.2012.05604.x
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发表时间：
2012-10
影响因子：
2.8
通讯作者：
Zhang Ning;Yufeng Gao;Yuanqiang Cai;Dayong Li;Wu Yongxin
中科院分区：
文献类型：
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作者：
Zhang Ning;Yufeng Gao;Yuanqiang Cai;Dayong Li;Wu Yongxin
地形对地震波有显著影响。波函数展开法是研究地形效应的常用方法，它能揭示波散射的物理机制，并能验证数值方法的准确性。本文用波函数展开法研究了平面SH波在非对称V形峡谷上的二维散射和绕射问题。通过一种新的区域分解策略，将含有V形峡谷的半空间划分为三个子区域。然后分别用三个坐标系中系数未知的波函数的无穷级数构造每个子区域的波场。然后，利用格拉夫加法定理，将三个波场都表示在同一坐标系中。通过满足辅助边界的连续性条件，得到未知系数。非对称V形峡谷波函数的级数解可简化为对称情况。在这项研究中的对称的情况下，结果非常符合那些在已发表的文献。为了揭示非对称地形对地表地震动的影响，在频域中进行了参数研究。地表和地下的瞬态响应在时间域中表现出波的传播和散射现象。最后，所提出的模型被成功地应用到两个理想化的横截面的Pacoima峡谷和翡翠峡谷。
SUMMARY Topographies have significant effects on seismic waves. The wavefunction expansion method has been frequently employed to study the topographic effect because this method can reveal the physics of the wave scattering and can testify the accuracy of numerical methods. The 2-D scattering and diffraction of plane SH waves induced by a non-symmetrical V-shaped canyon is examined here by using the wavefunction expansion method. Through a new domain decomposition strategy, the half-space containing a V-shaped canyon is divided into three subregions. Then the wavefield for every subregion is constructed in terms of an infinite series of wavefunctions with unknown coefficients in three coordinate systems, respectively. After that, three wavefields are all represented in the same coordinate system using the Graf addition theorem. The unknown coefficients are obtained by satisfying the continuity conditions of the auxiliary boundary. The proposed series solution of wavefunctions for a non-symmetrical V-shaped canyon can be reduced to a symmetrical case. Results in this study for the symmetrical case agree very well with those in the published literature. To show the effects of the non-symmetrical-geometry topography on the surface ground motion, a parametric study is carried out in the frequency domain. Surface and subsurface transient responses in the time domain demonstrate the phenomenon of wave propagating and scattering. Finally, the proposed model is successfully applied to two idealized cross sections of Pacoima canyon and Feitsui canyon.