Overtopping Erodibility Analysis for a Steep-Sloped Rockfill Embankment Dam

Erosion of embankment material during an overtopping event is one of the major mechanisms of failure for earthfill dams. The ability to analyze the progression of overtopping failure can prove useful in assessing the breakthrough risk of the dam, which involves understanding the behavior of the material that the dam is comprised of. While there have been studies on the behavior of smaller-grained materials such as clays and sands (e.g. Hahn et al 2000; Coleman et al. 2002; Hanson et al. 2005; Hanson et al. 2011), few have focused on erosion of larger-grained rockfill embankments. This paper presents the erosion progression analysis for a rockfill embankment dam with 80% (1.25H:1V) downstream slope and a protective upstream concrete face. The analysis is broken down into evaluation of various empirical relationships and erosion progression mechanisms to develop the most representative erosion progression model. Following this evaluation, failure of the dam was analyzed both deterministically and probabilistically