Experimental Study for Overtopping Discharges of Sea Dike having Low Mound and High Wave Wall (LMHW)

摘要

Overtopping discharge for sea dike having low mound and high wave wall (LMHW sea dike) is investigated with hydraulic experiments in this study.Vertical,Flare and Bullnose type wave walls are selected and Tetrapods (double layer) and Accropode (one layer) are adopted for armour layers of the front slope.The results of the hydraulic experiments are compared to the overtopping formulas for armoured rubble slopes and vertical sea dikes suggested by EurOtop Manual.Predicted overtopping discharges are underestimated as the roughness efficiency factors (γf) of armour blocks suggested by EurOtop are adopted when the overtopping formula for armoured rubble slopes sea dike is used.Meanwhile the predicted overtopping discharges agree well with the hydraulic experiments when the modified roughness efficiency factors redefined by multiplying efficiency factor of the heights of armoured crest berm and wave wall (γAR) are adopted.Return wall effects on a vertical wall (Kortenhaus et al.,2003;Pearson et al.,2004a) and the effects on a smooth dike slope (Van Doorslaer et al.,2015) in EurOtop Manual are investigated for Flare and Bullnose type wave walls.As a results of the comparison between experimental results and 2 formulas,return wall effect on a smooth dike was more valid for LMHW sea dike.