Date of Graduation

5-2023

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Degree Level

Graduate

Department

Civil Engineering

Advisor/Mentor

Clinton Wood

Committee Member

Kevin M Befus

Second Committee Member

Michelle L Barry

Keywords

Civil Engineering;Electrical Resistivity Tomography;Geophysics;Geotechnical Engineering;Internal Erosion;Levee Assessment

Abstract

Levee failures during flooding events can result in catastrophic loss of life and property. Soil erosion during high water events is a primary cause of levee failures. Accordingly, this research focuses on the geophysical assessment of internal erosion damage in levees. This thesis presents a case study utilizing Capacitively Coupled Resistivity (CCR), Direct Current Electrical Resistivity Tomography (DC ERT), and Multichannel Analysis of Surface Waves (MASW) to assess internal erosion damage at the Crawford County Levee System in Van Buren, AR, that occurred during the 2019 Arkansas River flood. Geophysical surveys acquired included longitudinal CCR, DC ERT, and MASW lines along the levee crest and landside toe. Additionally, extensive transverse DC ERT lines were acquired in zones of concentrated levee distress associated with internal erosion damage (e.g., slope stability failures and sand boils). Capacitively coupled resistivity surveys were found to be effective preliminary surveys and help identify target locations for further geophysical testing. A combination of perpendicular and transverse DC ERT surveys were found to be more effective than longitudinal MASW lines for the assessment of internal erosion damage. Additionally, repeat seasonal DC ERT lines were valuable for evaluating suspected internal erosion damage zones. Zones of potential internal erosion damage in the DC ERT lines were identified by high ER, thinning of the conductive top stratum, upward flow of high ER soils, and the presence of levee distress features in satellite imagery. The results support that internal erosion damage in levees can be assessed using geophysical methods. However, further geophysical testing at the project site, ground-truthing of interpreted zones of internal erosion damage, and application of the methods of this study to other project sites are needed to understand the uncertainties associated with the geophysical assessment of internal erosion damage in levees and the applicability of these results to other sites.

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