Experimental Investigation of the Effects of Soil Properties on Levee Breach by Overtopping

Abstract

Levee failure due to overtopping during floods is a common phenomena. An experimental study was conducted in the hydraulics laboratory, University of South Carolina, to develop an understanding of the effects of soil properties on the breaching process of earthen levees. A total of eight experiments were conducted. A new methodology to measure the subaqueous breach evolution has been developed and validated. Measurements of breach width evolution and headcut migration are shown to be related to soil properties. Inclusion of noncohesive, silt size crushed silica in the levee material (45% by weight) significantly reduced the peak discharge and breach evolution time compared to a levee constructed with sand alone. Increase in kaolin clay in the levee material led to an increase in unconfined compressive strength which in turn increased resistance to levee failure. Nondimensional equations relating the breach width evolution and headcut migration to the soil properties have been developed by performing a multivariate analysis of the experimental data.