Date of Graduation
5-2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Engineering (PhD)
Degree Level
Graduate
Department
Civil Engineering
Advisor/Mentor
Wood, Clinton M.
Committee Member
Hernandez, Sarah V.
Second Committee Member
Barry, Michelle L.
Third Committee Member
Befus, Kevin M.
Keywords
Electrical Resistivity Tomography (ERT); Geophysics; Geotechnics; Multichannel Analysis of Surface Waves (MASW); P-Wave Refraction
Abstract
Electrical resistivity tomography (ERT) has gained widespread application in geotechnical engineering as a non-invasive method for subsurface characterization. Despite its versatility, several challenges remain regarding its resolution capabilities, interpretive limitations, and integration with other investigative methods. This dissertation addresses three key applications of ERT, focusing on its effectiveness and limitations in resolving thin subsurface layers, detecting anomalies such as voids, and supporting environmental assessment in river restoration projects.
The first study investigates the ability of ERT to resolve thin, discontinuous clay layers beneath levees, using the Melvin Price Reach of the Wood River Levee on the Mississippi River as a case study. ERT surveys were conducted along both longitudinal and transverse profiles and were compared with multichannel analysis of surface waves (MASW) and historical boring logs. Results showed that while ERT successfully identified broader stratigraphic trends, its resolution was insufficient to reliably detect thin clay layers critical for evaluating seepage potential and internal erosion risk.
The second study evaluates the detectability of subsurface voids of varying sizes and depths in a karst terrain along Texas State Highway 29. A combination of ERT, seismic refraction tomography (SRT), and MASW were employed, along with ground-truthing through boreholes. ERT and SRT provided complementary information, with ERT responding to resistivity contrasts and SRT delineating structural anomalies. MASW, however, was found to be ineffective for this application. The results underscored the importance of a multi-method approach for anomaly detection in complex geological settings.
The third study explores the use of ERT for subsurface characterization following dam removal at Little Sugar Creek in Bella Vista, Arkansas. ERT survey lines were integrated with boreholes to assess sediment layering, bedrock depth, and bank stability. ERT proved effective in delineating erodible fine-grained sediments, coarse gravel deposits, and shale or limestone bedrock. These results provided valuable input for restoration design, erosion risk assessment, and geomorphic modeling.
Collectively, these studies highlight the potential and limitations of ERT in applied geotechnical and environmental settings. While ERT provides valuable spatial coverage and rapid data acquisition, it requires careful interpretation and is best used in conjunction with other geophysical and geotechnical tools. The findings contribute to improved practices for levee assessment, anomaly detection, and restoration planning, and offer practical recommendations for extending ERT to routine geotechnical investigations and infrastructure monitoring.
Citation
Rahimi, M. (2025). Subsurface Characterization Using Electrical Resistivity Tomography (ERT) Integrated with MASW, P-Wave Refraction, and Boring Results. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/5717
