Resistance of Laminar Drain Reinforcement Levee against Overflow Erosion

As a method for reinforcing against overflow erosion and infiltration, this study investigated a laminar drain reinforcement (LDR) levee, in which the drain layers are set on the back slope and connected to concrete panels using geogrid layers. We examined the resistance against overflow erosion of the LDR levee by large-scale model tests with a 1 m high model levee. We also compared the resistance of an armored levee, which is covered with concrete panels, and a GRS (geosynthetic-reinforced soil) levee, in which the geogrid layers are laid in the levee body with connecting concrete panels. The results of the model tests reveal that: (1) the LDR levee can maintain the initial height and shape for more than 150 min; by comparison, the times to levee failure were 87 and 102 min for the armored and GRS levees, respectively; (2) the LDR levee was shown to have a highly tenacious structure offering resistance to overflow erosion. In particular, panels easily flowed out with a slight gap (less than 1 cm) for the armored levee, while the LDR levee was able to prevent flowing out of panels and the erosion of the levee body, thanks to the laminar drain at the back slope, even when the gaps between the surface panels exceeded 5 cm.