Date of Award
1-1-2025
Document Type
Thesis
Degree Name
M.S. in Engineering Science
First Advisor
Lance Yarbrough
Second Advisor
Robert Holt
Third Advisor
Ron Counts
School
University of Mississippi
Relational Format
dissertation/thesis
Abstract
This thesis uses geological field data, laboratory characterization of sediments, and multiple computational models of slope stability to investigate a landslide that occurred in Calhoun County, Mississippi. The primary hypothesis is that intense rainfall led to the saturation of the slope, triggering failure through the reduction of shear strength.
Fieldwork included drilling at the failure site to obtain subsurface samples and drone-based site characterizations. Laboratory analysis included soil descriptions, grain size analysis, and Atterberg limit testing. Sample characterizations revealed a stratified soil profile dominated by fine-grained silts and clays, including an organic-rich lignite layer (OL). Strata generally exhibit low permeability and high shrink-swell potential in some layers. These conditions are prone to strength reduction under saturation and are conducive to perched water table development, supporting the hypothesis that saturation was a key triggering mechanism.
Computational modeling using RocScience Slide2 software employed multiple Limit Equilibrium Methods (LEM) to evaluate the slope under dry and saturated scenarios. While dry conditions produced stable factors of safety, saturated conditions resulted in critical values—specifically, a Factor of Safety (FoS) of 1.00 under the Janbu Simplified method—indicating the slope was on the verge of failure. Sensitivity analysis further identified the OL and CH layers as highly sensitive to cohesion and pore pressure changes, confirming their role in slope instability.
LiDAR-based digital elevation models and geologic maps identified other areas with similar topographic and subsurface conditions that are potential failure zones in Calhoun County, particularly near the Skuna River. These results offer valuable insight into regional landslide hazards and provide a framework for slope risk assessment and mitigation in similar geologic settings.
Recommended Citation
Grames, Miles Heath, "Slope Stability Hazard Investigation of Calhoun County, Mississippi and The County Road 210 Landslide" (2025). Electronic Theses and Dissertations. 3284.
https://egrove.olemiss.edu/etd/3284