Evaluating the mechanisms of erosion for coarse-grained materials

Efforts are currently underway by the U.S. Army Corps of Engineers (USACE) to perform a risk assessment of all dams and levees within their portfolio. The vast majority of that portfolio is earthen structures. Findings from the assessments have shown that the major risk drivers for these earth structures are related to erosion (internal and external), overtopping, poorly designed and constructed intrusions (such as pipe crossings), and other factors to a lesser degree (such as burrowing animals). Therefore, the USACE is currently investigating several of these failure modes with emphasis on internal and external erosion. This paper will highlight efforts to investigate surface erosion, which may lead to breach formation and growth, by use of laboratory scale model testing to understand and properly capture the physics of the problem. These data are informing improvement and development of numeral methods for use in ongoing risk assessments.