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DIFFRACTION OF ANTI-PLANE (SH) WAVES
BY SURFACE ELLIPTICAL TOPOGRAPHIES
IN AN ELASTIC HALF-SPACE
by
Alongkorn Amornwongpaibun
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(CIVIL ENGINEERING)
December 2011
Copyright 2011 Alongkorn Amornwongpaibun
Object Description
| Title | Diffraction of anti-plane (SH) waves by surface elliptical topographies in an elastic half-space |
| Author | Amornwongpaibun, Alongkorn |
| Author email | amornwon@usc.edu;alongkorn.new@gmail.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Civil Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2011-07-27 |
| Date submitted | 2011-10-03 |
| Date approved | 2011-10-04 |
| Restricted until | 2011-10-04 |
| Date published | 2011-10-04 |
| Advisor (committee chair) | Lee, Vincent W. |
| Advisor (committee member) |
Wong, Hung L. Udwadia, Firdaus E. |
| Abstract | The study presented in this dissertation aims at the ground motion assessment of various two-dimensional hill models subjected to incident plane SH waves in an elastic half-space. The exact, analytic solutions to the boundary-valued problem, based on method of wave function expansion in elliptical coordinate 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 semi-elliptical interface. ❧ In the study we found out that the existence of a hill results in complex pattern of surface displacement. Generally 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 without the abrupt jump at that edge of the. 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; note that these amplifying and de-amplifying effects are dependent on the size of tunnels. The bigger the tunnel is, the stronger the effects are. ❧ We also found out that the effect of the semi-elliptical tunnels on ground surface motion is dissimilar to the effect of the full-elliptical ones. Since 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; the tunnel becomes better obstruction when the incidence is propagating normal to its major axis. |
| Keyword | anti-plane wave; diffraction; elliptical; scattering; SH wave |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m |
| Rights | Amornwongpaibun, Alongkorn |
| Access conditions | The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the author, as the original true and official version of the work, but does not grant the reader permission to use the work if the desired use is covered by copyright. It is the author, as rights holder, who must provide use permission if such use is covered by copyright. The original signature page accompanying the original submission of the work to the USC Libraries is retained by the USC Libraries and a copy of it may be obtained by authorized requesters contacting the repository e-mail address given. |
| Repository name | University of Southern California Digital Library |
| Repository address | USC Digital Library, University of Southern California, University Park Campus MC 7002, 106 University Village, Los Angeles, California 90089-7002, USA |
| Repository email | cisadmin@usc.edu |
| Archival file | uscthesesreloadpub_Volume71/etd-Amornwongp-309.pdf |
Description
| Title | Page 1 |
| Full text | DIFFRACTION OF ANTI-PLANE (SH) WAVES BY SURFACE ELLIPTICAL TOPOGRAPHIES IN AN ELASTIC HALF-SPACE by Alongkorn Amornwongpaibun A Dissertation Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (CIVIL ENGINEERING) December 2011 Copyright 2011 Alongkorn Amornwongpaibun |
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