Date of Award

Spring 1-1-2011

Document Type

Thesis

Degree Name

Master of Science (MS)

First Advisor

John S. McCartney

Second Advisor

Ronald Pak

Third Advisor

Matthew DeMarco

Abstract

Compaction grouting is one of the most common ground improvement techniques in geotechnical practice. Traditional quality assurance methods for compaction grouting typically involve evaluation of grout injection parameters and intrusive point measurements. An issue with these methods is that they may not reflect the entire treated soil volume. A geophysics-based evaluation method such as 3-D seismic tomography provides an alternative technique to evaluate the volumetric improvement of soil profiles before and after compaction grouting. Specifically, 3-D seismic tomographic images can be used to visualize and quantify the distribution in compression wave (p-wave) velocities to measure and estimate spatial variations in improvement of subsurface materials in a rapid, non-intrusive, and inexpensive manner.

3-D seismic tomography was applied in this study to two roadway rehabilitation projects to investigate its suitability in quality assurance programs for shallow grouting of poor roadway subgrades. This study presents the details of these projects as well as related grouting field operations, seismic data collection procedures, and raw 3-D seismic tomography results. Several analytical methods are proposed to interpret the tomography results to quantify the degree of improvement in the seismic velocity distributions at the sites following grouting. The potential applications of 3-D seismic tomography for verifying effectiveness of future compaction grouting projects is explored and recommendations are made based on lessons learned.

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