Test Study on Overtopping Breaching Process of Earth Dam and Peak discharge

In order to explore the relationship between peak discharge of earth dam and breaching process, a series of indoor flume experiments have been done on earth dam (1 meter height) constructed by wide gradation and cohesionless materials. Dam erosion process and hydraulic parameter changing process have been measured in the condition of flood overtopping. The result of the experiment indicates that depending on the way of the overtopping flow, the density of fill and gradation composition of the dam's constructional material, the overtopping erosion process can be classified into 3 types such as layer-by-layer erosion, entire overtopping erosion and headcut erosion. There is a very close relationship between the peak discharge and the breaching process. The quicker of dam-break happens, the bigger the peak discharge is. In the same situation, the peak discharge of headcut erosion increases 40% to the one of layer-by-layer erosion.