|Title:||Focusing phenomenon and near-trapped modes of SH waves||Authors:||Jeng-Tzong Chen
|Keywords:||SH wave;null-field boundary integral equation method;degenerate kernel;focusing;near-trapped mode||Issue Date:||8-Sep-2016||Publisher:||Springer||Journal Volume:||15||Journal Issue:||3||Start page/Pages:||477-486||Source:||Earthquake Engineering and Engineering Vibration||Abstract:||
In this study, the null-field boundary integral equation method (BIEM) and the image method are used to solve the SH wave scattering problem containing semi-circular canyons and circular tunnels. To fully utilize the analytical property of circular geometry, the polar coordinates are used to expand the closed-form fundamental solution to the degenerate kernel, and the Fourier series is also introduced to represent the boundary density. By collocating boundary points to match boundary condition on the boundary, a linear algebraic system is constructed. The unknown coefficients in the algebraic system can be easily determined. In this way, a semi-analytical approach is developed. Following the experience of near-trapped modes in water wave problems of the full plane, the focusing phenomenon and near-trapped modes for the SH wave problem of the half-plane are solved, since the two problems obey the same mathematical model. In this study, it is found that the SH wave problem containing two semi-circular canyons and a circular tunnel has the near-trapped mode and the focusing phenomenon for a special incident angle and wavenumber. In this situation, the amplification factor for the amplitude of displacement is over 300.
|Appears in Collections:||河海工程學系|
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