Events Calendar

Oral Defense: Diffraction of Anti-Plane (SH) Waves by Surface Elliptical Topographies in an Elastic Half-Space

Speaker: Alongkorn Amornwongpaibun, CEE Ph.D. Candidate

Abstract: The exact, analytic solutions to various two-dimensional semi-elliptical hill models subjected to incident plane SH waves in an elastic half-space are presented These require the technique of angular half-range expansion in elliptical coordinate to deal with mixed-boundary condition arisen during mathematical implementation of all hill models; the traction-free boundary condition at the surface of the elliptical hill and the continuity of displacement and stress at the interface.

In the study we found out that the existence of a hill results in complex pattern of surface displacement. For nearly grazing angle, a hill shields the propagating waves, resulting in a standing wave pattern in the coming direction and the focusing of the amplitude at the far edge of the hill. In addition the presence of full-elliptical tunnels resulted in more prominent standing waves, and amplitudes of ground motion in the neighborhood of unity or less on the far end may be monitored. We discovered that the presence of a full-elliptical tunnel amplifies maximum displacement by 30%-70% from corresponding value of reference (inexistence of a tunnel) for the horizontal incidence and de-amplifies maximum displacement in the range of 1%-15% for the vertical incidence.

In contrast to the full-elliptical tunnel model, horizontal incidences are able to slip underneath semi-tunnels. The weaker standing waves on the left side and weaker shadow zones associated with high jumps of the displacement amplitude at the far edge of the hill are observed. However, when the incident waves are nearly vertical, the stronger shielding effect due to semi-elliptical tunnels than to full-elliptical ones are detected. It could be said that the hinder efficiency of an elliptical tunnel depends on the direction of wave passage. In general the tunnel becomes better obstruction when the incidence is propagating normal to its major axis.

Location: Kaprielian Hall (KAP) - 345

Audiences: Everyone Is Invited

Contact: Evangeline Reyes