Date of Award

Spring 2020

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geological Engineering

Committee Chair

Larry Smith

First Advisor

Mary MacLaughlin

Second Advisor

Phillip Curtiss

Third Advisor

Emily Ward

Abstract

As our cities expand into geologically sensitive areas across the greater Rocky Mountain region and beyond, quantitative methods of assessment are increasingly critical for the development of evidence-based alternatives to avoid or mitigate geologic hazards. Unmanned Aerial Vehicle (UAV) photogrammetry can improve these geologic investigations by enabling remote visual inspection, measurement, and spatial analysis while eliminating many of the physical access limitations that contribute to field sampling bias and human error. UAV photogrammetry technology was employed to evaluate fragmental rock fall hazards at two locations in the Rimrocks region of south-central Montana, Zimmerman Trail Road and Phipps Park. At these sites, active retrogressive rock slope instability caused by differential erosion has produced damaging rock fall. Nadir and oblique imagery of the 35-acre Zimmerman Trail Road and 13-acre Phipps Park study areas was acquired with a DJI Phantom 4 Pro UAV and processed into digital photogrammetry with Pix4Dmapper. Remote methods of analysis were employed to measure the orientation of discontinuities in rock fall source areas and to quantify rock fall susceptibility. At Zimmerman Trail Road, photogrammetry data products were used to numerically differentiate rock fall hazard zones along the 0.3-mile long rock slope in accordance with the detailed Rock Fall Hazard Rating System (Pierson, 1991). At Phipps Park, photogrammetry was used to measure the size, run out distance, and change in elevation of high energy rock fall and to generate 2D and 3D slope profiles, which were used to model potential future rock fall. The methods and findings demonstrate how nadir and oblique UAV photogrammetry can be used to implement quantitative, defensible approaches for evaluating rock fall susceptibility and run out potential in geologic investigations of fragmental rock fall hazard areas.

Comments

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Geoscience: Engineering Geology Option

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