Scattering of seismic waves by cracks in multi-layered geological regions: I. Mechanical model |
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| Authors: | P S Dineva G D Manolis |
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| Institution: | a Institute of Mechanics, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria;b Department of Civil Engineering, Aristotle University, 54006 Thessaloniki, Greece |
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| Abstract: | In this work, a hybrid boundary integral equation method (BIEM) is developed, based on both displacement and hypersingular traction formulations, for the analysis of time-harmonic seismic waves propagating through cracked, multi-layered geological regions with surface topography and under plane strain conditions. Specifically, the displacement-based BIEM is used for a multi-layered deposit with interface cracks, while the regularized, traction-based BIEM is used when internal cracks are present within the layers. The standard uni-dimensional boundary element with parabolic shape functions is employed for discretizing the free surface and the layer interfaces, while special discontinuous boundary elements are placed near the crack tips to model the asymptotic behaviour of both displacements and tractions. This formulation yields displacement amplitudes and phase angles on the free surface of a geological deposit, as well as stress intensity factors near the tips of the cracks. Finally, in the companion paper, numerical results are presented which show that both scattered wave and stress concentration fields are sensitive to the incidence seismic wave parameters and to specific site conditions such as surface topography, layering, the presence of cracks and crack interaction. |
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| Keywords: | Elastic waves Hybrid BIEM Hypersingular integrals Interface cracks Internal cracks Multi-layered geological deposits Site effects Wave propagation |
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