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

Abstract

Dike erosion is a crucial issue in coastal and fluvial flood risk management. These defense structures appear vulnerable to extreme hydrological events, whose potential occurrence risk seems to be recently increased due to climate change. Their design and reinforcement is, however, a complex task, and although numerical models are very powerful nowadays, real processes cannot be accurately predicted; therefore, physical models constitute a useful tool to investigate different features under controlled conditions. This paper presents some laboratory experimental results of erosion of a sand dike produced by the impact of a dam break wave. Experiments have been conducted in the Water Engineering Laboratory at the University of Cassino and Southern Lazio, Italy, in a rectangular channel: here, the sudden opening of a gate forming the reservoir generates the wave impacting the dike, made in turn of two different, almost uniform sands. The physical evidence proves that the erosion process is strongly unsteady and significantly different from a gradual overtopping and highlights the importance of apparent cohesion for the fine sand dike. The experimental results have also been compared against the ones obtained through the numerical integration of a two-phase model, which shows the reasonable predictive capability of the temporal free surface and dike profile evolution.

A multi-parameter calibration method for the numerical simulation of morphodynamic problems

“…The adopted reference frame axes coincide with the channel bottom and the gate position in the longitudinal and vertical directions, respectively (Evangelista, 2015). In this way, the evolution of the time-and spacedependent processes can be properly evaluated.…”

“…In this way, the evolution of the time-and spacedependent processes can be properly evaluated. The obtained experimental data have been used already in a previous work (Evangelista, 2015) to test the predictive capability of a numerical code based on a morphodynamic depthintegrated two-phase approach (Greco et al, 2012).…”

“…The results of the laboratory experimental campaign have been utilized already (Evangelista, 2015) to validate the capability of the numerical model of predicting the physical evidence and its reliability for analyzing also this kind of scenario.…”

“…1). A downstream trapezoidal sand dike is built upon a wooden ramp and, therefore, the dike overtopping occurs if the hydrodynamic energy possessed by the wave is sufficient (Evangelista, 2015).…”

“…These experiments have been performed in a horizontal rectangular channel (Evangelista et al, 2015a;Evangelista et al, 2014b), where a dam break is simulated through the sudden opening of a gate closing an upstream reservoir (Fig. 1).…”