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Proceedings Paper

Crosshole seismic tomography across a masonry dam
Author(s): Joe Wong
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Paper Abstract

An intensive crosshole seismic survey was done across a 700-foot-long stone-masonry dam. It involved measurements on six connected panels each approximately 100 feet in width extending completely across the dam from abutment to abutment. The objective was to provide tomographic images of P-wave velocity and dynamic elastic moduli of the dam and foundation materials along the axis of the dam. Field seismograms were recorded with an airgun source and hydrophone detectors. Data analysis included interactive time-picking, plotting of common source gathers, and tomographic imaging using an iterative back-propagation technique. Color-coded tomograms of velocity and dynamic Young's modulus were produced and correlated with geological and geophysical data measured on drill core samples. Low values of velocity and dynamic elastic modulus correlated with low RQD and high fracture frequency. The tomograms showed significant variations of mechanical properties in the stone masonry dam and its foundation. The colored tomograms were useful in highlighting zones of weak rock possibly requiring remedial action. They also assisted engineering evaluation of the dam by providing a detailed two-dimensional distribution of mechanical properties which can be used as ground truth data for numerical modeling of stress-strain fields.

Paper Details

Date Published: 12 May 1995
PDF: 9 pages
Proc. SPIE 2457, Nondestructive Evaluation of Aging Structures and Dams, (12 May 1995); doi: 10.1117/12.209404
Show Author Affiliations
Joe Wong, JODEX Applied Geoscience Ltd. (Canada)

Published in SPIE Proceedings Vol. 2457:
Nondestructive Evaluation of Aging Structures and Dams
Soheil Nazarian; Larry D. Olson, Editor(s)

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