Experimental Study on Effect of Sediment Size on River Dyke Breach Characteristics Due to Overtopping

Abstract

Flood discharge induced overtopping flow through the river dyke cause large destruction on the environment, infrastructure and the countryside every year in the world. The failure by overtopping constitutes the primary failure modes of earth embankment besides internal erosion. There were a lot of researches conducted to understood embankment dam failure and few for the river dyke breach, but the lateral widening of breach process and the time of failure prediction is poorly understood. The breaching process of a river dyke is very complex because of manifold interactions between water, soil and structure. Enlargement dynamics and final breach geometry are also the result of boundary and initial conditions affecting the dyke Therefore, Preliminary Laboratory tests were conducted to investigate the dynamic lateral widening process and breach characteristics. The whole process was recorded optically using video and threedimensional camera for the detail analysis of the breaching phenomena. The result indicates the important effect of sediment size on the dynamic lateral widening process, breach discharge and the time of failure. A systematic variation of the sediment size reveals important findings regarding breach characteristics. Finally the curve for the time of failure is also proposed which requires testing with future experiments. The final experiment with new experimental setup considering actual parallel flow through the dyke is conducting now with the lesson learnt from this experiment.