Date of Award

2018

Document Type

Open Access Master's Thesis

Degree Name

Master of Science in Geology (MS)

Administrative Home Department

Department of Geological and Mining Engineering and Sciences

Advisor 1

Thomas Oommen

Advisor 2

John S. Gierke

Committee Member 1

Luke Bowman

Abstract

The Enguri Dam forms a reservoir in a seismically active area in the foothills of the Caucasus Mountain range near Jvari, Georgia. The slopes are steep, highly fractured, and weathered, which make them at risk to failure during or following extreme rainfall events. Hydroelectricity produced by the water retained by the 271-m dam provides almost half of the electricity for the country. The reservoir perimeter is more than 40 km and the surrounding slopes span an area of more than 30 km2. The size of the area and paucity of slope data have made slope-failure hazard assessment of the broader area impossible. Only limited previous work has been completed and it was focused on a single creeping landslide. This work evaluated the landslide hazards for the reservoir area using data from past studies, field investigations, and remotely sensed inputs, integrated with Geographic Information System (GIS) based slope stability analysis. The GIS-based Probabilistic Infinite Slope Analysis modeling (PISA-m) program was used to evaluate the static slope stability of the region. The geotechnical properties (e.g., unit weight, the angle of internal friction, cohesive strength, and moisture content) were obtained from published literature and field data collection. The remotely sensed Normalized Difference Vegetation Index (NDVI) derived from Landsat 8 was used to account for the vegetation distributions in calculations of root strengths for the slopes. The uncertainties in the input parameters were estimated using extreme value distributions. The static and seismic slope stability analysis reveal that the areas proximal to the dam have low safety factors against sliding and are very susceptible to slope instability, especially to seismic events. The verification of the modeled stability with the landslides mapped using high-resolution remotely sensed data and fieldwork indicates that the PISA-m provides a promising program for regional slope stability analysis. Furthermore, to better understand the mechanics of the sliding area, we performed a Finite Element slope stability analysis with Rocscience Phase2 and a Limit Equilibrium analysis with Rocscience Slide.

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