Date of Award

1-1-2013

Document Type

Open Access Dissertation

Department

Civil and Environmental Engineering

Sub-Department

Civil Engineering

First Advisor

Richard P. Ray

Second Advisor

Dimitris C. Rizos

Abstract

The research described involved analyzing and characterizing changes to propagating surface waves that are caused by items embedded in a half-space consisting of a soil medium. Numerical and experimentally obtained data of three-dimensional surface wave responses to dynamic impulse loading were examined. Results from this research are compared to changes to surface waves observed in previous investigations that were caused by the presence of voids and inclusions embedded in an elastic half space. The focus of this work was to identify whether the characteristic responses identified in previous studies, based substantially on analytical and finite element analyses results, can be replicated in an experimental setting.

Both the numerical studies and experimental studies indicate that, above a threshold limit, wavelet analyses can be effective in identifying inclusions in an experimental environment. In general, the characterizations of behavior that were observed in previous studies are corroborated in the numerical studies for the void object with the exception that reflections caused by oscillations of the void object, which is local in space rather than a "ring" as inferred by the axi-symmetric models used, are more apparent than responses created by reflections off of the near and far faces of the void. For the buried solid, oscillations corresponding to rigid body vibration of the beam, rather than reflections of the impedance contrasts between the beam and soil are dominant. For the experimental results, although changes to both the dispersion curves and CWT plots are sufficiently large to indicate the presence of the inclusion, for inclusions larger than a threshold limit, the changes to the power in the surface wave pattern characterizations and in the phase velocity are not sufficiently clear or consistent to reliably quantify the depth, size, stiffness, density or shape of the buried object.

The investigation described in this work represents an extension of previous investigations both in evaluating numerical results of three-dimensional models of inclusions and in evaluating experimental results using wavelet analysis methods.

Rights

© 2013, Thomas Houston

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