An Investigation of Seismic Rayleigh Waves for Material Characterization and Underground Void Detection
by Chris Phillips, Masters of Science in Earth Science, Thesis, University of Waterloo, 2001
The investigation
of seismic Rayleigh waves was undertaken for the purpose of developing new
methods for material characterization and underground void detection. Laboratory
testing led to the development of a Rayleigh wave phase method to determine
lateral medium homogeneity, called the distance analysis of surface waves
(DASW) method, and to a Rayleigh wave energy method for the detection of underground
voids, called the power spectral density analysis method for void detection.
The DASW method was verified by numerical simulations for four different cases:
a half space, a half space comprised of two laterally different mediums, a
medium with linear variation of elastic properties, and a half space with
a rectangular void. The power spectral density analysis method was verified
through four field sites where voids were known to exist: two geophysical
test sites with buried barrels, a dolostone quarry with dissolution features,
and a mine site with known mine workings. The testing results were very favorable
and illustrate the strong potential of each method.
Also presented in this thesis is a literature review of geophysical methods that have been used for the detection of underground voids and the setup, calibration, and verification procedure used for the numerical simulations.