Underseepage analysis of levees on two-layer and three-layer foundation

Abstract A simplified numerical model for the analysis of levee underseepage is developed and presented. Idealization of the subsurface hydrogeologic conditions was achieved using two-layer and three-layer representation of the flow domain. Data from Magnolia levee, located in Magnolia, Ohio, were used to demonstrate the model applicability by comparing exit hydraulic gradient (i) values from the simplified model to predictions from 2-D finite element analysis (FEA). Results from the simplified model indicated that i values were merely dependent on the ratio of the foundation permeability (K fx ) to the blanket permeability (K by ). The i values from the FEA closely matched those from the simplified model for K fx /K by ratios less than 2000 and assuming permeability anisotropic ratio (rk) = 1. Piezometer data from the Sny Island levee, located in Quincy, Illinois, were used to demonstrate the applicability of the three-layer model.