Experimental and Numerical Study for Submergaed Dam Failure Shape Under Water Overtopping Impact

An experimental and numerical models have been measured and simulated to evaluate earth dams erosion at its front crest. Application model was simulated to study nourished non-cohesive soil behind submerged dam for coastal reclamation. Experimental relative erosion crest height profiles for earthen dam have been measured due to overtopping in the Hydraulic Laboratory of Alexandria University. Laboratory flume dimensions were 8.6 m length, 0.4 m width and 0.5 m height; it has vertical Plexiglas`s sidewalls to track erosion and water surface profile using a high-definition (HD) video camera with image processing technique. A centrifugal pump with capacity reached to 415 m³/hr has been used.

Numerical model (Mike 21 coupled model) based on (Navier Stokes ,Shallow Water Equation) has been used to compare erosion with experimental results to be calibrated and validated then applied model has been simulated to evaluate stability of sediment behind submerged dam which protect non cohesive nourished sediments on Egyptian north west coast.

Failure behavior of tested dam has measured for dimensionless crest height change to its time and distance. Models have tested for different dam downstream slopes, crest heights and crest widths.

Earth dam erosion occurred in three stages, first along the downstream slope, second at top of dam reducing width and third has reduced crest height. Crest height relative ratio(Z^*) to its time changes slowly till dimension less time parameter (t^**) reached to 150, 120, 90, 85 and 75 according to downstream slope 1:1, 2:1, 3:1 and 5:1 respectively.

Numerical coupled model studied erosion at submerged non cohesive dam for coastal lagoon construction road at New Alaamein to study stable sediment size to protect sides from tidal wave erosion.