Scattering of plane SH-waves by cylindrical canals of arbitrary shape

A boundary method is used to solve numerically the problem of scattering and diffraction of SH-waves by cylindrical canals of arbitrary shape in a homogeneous, linear, elastic, and isotropic half-space. A least-square technique has been employed to solve this problem. Results are obtained using a multiple expansion in terms of Henkel's functions. Displacements and stresses near and in the canal wall have been investigated and a comparison with known exact and approximate solutions for SH-wave motion has been studied. Numerical results for displacement and stress amplitudes for different geometries are presented.

The stress and displacement amplitudes in the canal wall and on nearby ground surface change rapidly from one point to another. The higher excitation frequencies lead to greater complexity of the computed motions. For grazing and nearly grazing incidences, a shadow zone is developed behind the canal.