Large-Scale Experiment and Numerical Modeling of a Riverine Levee Breach

Abstract

This study aims to clarify the mechanism of riverine levee breach and propose a new 6 numerical model for that phenomenon. We performed large-scale experiments of overtopping breach 7 using an experimental flume located on the floodway of an actual river channel. By taking advantage 8 of the scale of the flume, we monitored the levee breach process with state-of-the-art observation 9 devices under highly precise hydraulic conditions. We performed four test cases with variations of 10 inflow rate, levee material and levee shape, and monitored the levee breach quantitatively using 11 acceleration sensors installed in the levee body. From the results of the experiments, we categorized 12 the breach process into four stages, focusing on the breach progress and hydraulic characteristics. 13We determined that the correlation between the breached volume and the hydraulic quantities of 14 velocity, water level and Shields number can be expressed by an equation similar to that for bed load 15 transport. Finally, we proposed a two-dimensional numerical model by integrating the experimental 16 results into geomechanics, and we obtained a fine reproduction result.

Experiments and Numerical Simulations of Dike Erosion due to a Wave Impact

“…Pickert et al [13] pointed out that the apparent cohesion due to pore-water pressure influences the stability of side slopes. More recently, large-scale experiments of overtopping breach were performed by Kakinuma and Shimizu [14] on an experimental flume located on the floodway of an actual river channel. Feliciano et al [15] studied the effects of soil properties on levee breach by overtopping with the aim of increasing the resistance to levee failure, whereas Schmocker et al [16] also experimentally investigated the effect of the grain size distribution.…”

“…An interesting model has been proposed by Mizutani et al [1], who also took into account the effects of saturation and sediment size of embankment materials on the erosion process and, specifically, the effects of infiltration and resisting shear stresses due to the suction of unsaturated grains. Two-dimensional (2D) full shallow-water models for embankment breach have also been recently developed by Guan et al [26] and by Kakinuma and Shimizu [27].…”

Applying Mechanistic Dam Breach Models to Historic Levee Breaches

“…While a dam has a basically static headwater, the river approaching a levee breach is typically in flood stage and moving with considerable momentum that is only increased by the sudden breach opening. The angle of approach may also have impact on the breach opening geometry, favoring the downstream edge for erosion [6].…”

Overtopping breaching of river levees constructed with cohesive sediments

“…River levee breach is quite different from that of embankments constructed normal to the flow in morphology, hydraulics and inflow variation characteristics (Kakinuma and Shimizu, 2014). Moreover, measured data of cohesive levee breach have not been reported until now.…”

“…Kakinuma and Shimizu (2014) conducted several groups of large-scale experiments on breaching of non-cohesive river levees and subdivided the breach development into four stages. Yu et al (2013) studied the influencing factors on the overtopping breaching process of non-cohesive levees and the breach discharge properties.…”