Date of Award

January 2019

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

First Advisor

Yeo H. Lim

Abstract

The introduction of spur dikes into a river flow field can have many far-reaching positive effects on the stability of a river channel. While the flow velocity directly at the spur dike tip or crest may increase, a large embayment area downstream of the spur dike will form with reduced flow velocities. Due to the increase in flow velocity at the spur dike, a scour hole will form. Scour is the leading cause of failure of hydraulic structures. In the past many hydraulic structures were tested by building scale prototype models, this method is very costly and hard to model all factors correctly. The recent introduction and widespread use of two-dimensional numerical models allow for increased efficiency and accuracy of hydraulic modeling. This recent breakthrough allows for relationships between dynamic variables and the estimated scour depth to be developed. The length of the spur dike and the flow rate were varied in the experiments. It was found that as the length of a spur dike increases, the depth of the scour also increases. This held a stronger correlation than the increase in flow rate. A relationship was developed between the maximum flow velocity, the upstream flow velocity, and the upstream Froude number to determine the maximum scour depth. This relationship proved to be more accurate than past relationships proposed using data from physical model analysis. The new relationship lowered the percent-error from 14% to 1% when the predicted scour depths were compared with the measured scour depths. The error was reduced from 7.3% to 1.6% for the long spur dike simulations and from 21.4% to 13.2% for the short spur dike simulations.

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