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Title: HEADCUT MIGRATION ANALYSIS OF A COMPACTED SOIL (ADD ACCEPT. DATE)

Author
item Hanson, Gregory
item Robinson, Kerry
item Cook, Kevin

Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Niagara Falls is one of the more famous headcuts, but in reality headcuts come in many sizes and occur in many places across the landscape. The rate at which headcuts migrate upstream and what parameters affect this migration are important in engineering design of earth spillways, embankments, and levees. When a headcut forms and migrates due to flow through a spillway or flow over an embankment, the concern is whether the headcut will move through the structure and release the body of water behind it, endangering life downstream. Flume tests were conducted on headcut migration and analyzed in this paper based on three simple physically based headcut migration models. This study showed that the measured soil properties such as density, water content, strength, and erodibility were significantly correlated to the material-dependent parameters from these three equations. Depth averaging algorithms were also ofound to be an adequate approach for determining the material-dependent parameter for headcuts with multiple materials. This study is of value to researchers and practitioners dealing with design of spillways, embankments, levees, and landscape management.

Technical Abstract: Predicting headcut migration is a complex problem. The headcut migration process may involve mass failure and/or detachment of the soil at the headcut face, removal of the material from the base of the headcut, and downward erosion of the channel bed at the base of the headcut. When the leading edge of a headcut breaches a reservoir, levee, or embankment, the outlet area and head increase, as does the discharge. This results in increased flooding downstream. Therefore, prediction of headcut migration is an important aspect in analysis of these sites. Headcut migration tests on a compacted soil were conducted in a 1.8-m wide and 29-m long flume with 2.4-m high sidewalls. The simple relationships for headcut migration have almost universally focused on energy at the overfall as the driving mechanisms. Three simple physically based headcut migration equations that separately lump material-dependent parameters and flow-dependent parameters swere used in this study to analyze the results of the headcut migration tests. Soil properties such as density, water content, strength, and jet index were measured and observed to have a significant correlation to the material-dependent parameters of the physically based headcut migration equations. Algorithms for determining the material-dependent parameters for multiple materials were also analyzed.