Abstract: Seven dam break experiments were designed, with different inner slopes and gradation of grain building dam, to study effect of the conditions above on the process of dam break. According to photography of dam break, four stages were observed, and flow erosion of dam body was the most intense in stage Ⅲ. In stage Ⅰ, inner slope was eroded; In stage Ⅱ, the top of the breach was eroded; In stage Ⅲ, outer slope was eroded; In stage Ⅳ, the shape of the dam body kept steadily and water level of reservoir gradually came to the constant. Using the WYG-Ⅱwater level measurement system, the real-time water lever data of the reservoir can be obtained. The result of the experiments indicate that the steeper of the inner slope was, the more peak discharge of dam break was; if the non-uniformity coefficient was bigger, the peak discharge of dam break increase at first because of lee erosion, but decrease at last because of the conceal function. Empirical formula of peak discharge of dam break was established by single factor analysis.
