Date of Award

2-28-2019

Document Type

Thesis

Degree Name

Bachelor of Science (B.S.) in Geology and University Honors

Department

Geology

First Advisor

Adam Booth

Subjects

Discrete element method, Debris avalanches -- Mathematical models, Coarse woody debris

DOI

10.15760/honors.667

Abstract

Many studies have examined runout behavior of debris flows on various slopes and in different environments, but few have explicitly modeled their coarse woody debris component. Simulating a coarse-grained debris flow snout including coarse woody debris can be achieved using discrete element modeling. Before modeling the entire system, each parameter that influences the model must be determined and analyzed. Using 5 m resolution IfSAR data from Sitka, Alaska as the control topography, I conducted a sensitivity analysis of the behavior of a single particle as it travels downslope. Parameters of relevance are normal and tangential contact stiffness, viscous damping coefficient, and friction coefficient. Each parameter influences the amount of time that the particle spends in the air (i.e., making no contact with the topography), with stiffness and damping parameter being the most influential parameters on time spent in the air. For future work, using parameter values of 9.5e8 N/m for normal contact stiffness, 4.8e11 N/m for shear contact stiffness, a viscous damping coefficient of 0.8, and a friction coefficient of 0.6 to simulate boulders with a density of 2600 kg/m3 and radius of 5.0 meters should be optimal for simulating debris flow dynamics of the coarse-grained snout. Finally, with appropriately behaving sediment, coarse woody debris may be included in the model and the system can be observed.

Persistent Identifier

https://archives.pdx.edu/ds/psu/27953

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