ZHANG Da-wei, QUAN Jin, HE Xiao-yan, HUANG Jin-chi (China Institute of Water Resources and Hydropower Research, Beijing 100038, China)

Abstract: The overtopping breaching experiment for pilot channel has been carried out using two significantly different kinds of sand specimens to give a supplement and perfection for the breaching experiment of barrier dam. The tests indicate that the breaching phenomenon has obvious difference between the two kinds of dam under the same condition. When the baffle is removed, the breaching process of dam made of fine particle is dominated by the strong down cutting erosion and breaks more easily. However, the breaching process of dam made of coarse particle is dominated by the weak headward erosion caused by seepage outflow. The headward erosion face gradually develops to upper side and only when it reaches to the pilot channel vicinity, the dam can break easily. The tests also found that the downstream slop of dams has obvious effect on the breaching process. The steeper the slope is, the more easily the dam break, the bigger the average broadening rate of the breach is. A conceptual physical dam breach model based on the de Vries erosion formula for the computation of the outflow hydrograph has been developed. Good adaptability is showed through the verification of the model by using the measured test data.

Key words: barrier dam, flume experiment, overtopping breach, numerical model

Published in: Journal of Hydraulic Engineering, Vol. 43, No. 8, 2012