Abstract: Combined with the advantages of a single dam building method,the mixed damming process of tailings pond can make full use of tailings accumulation,reduce the cost of dam construction,and adapt to complex terrain. In order to ex plore the behavior characteristics of the dam failure process of a mixed damming tailings pond,this paper established a three dimensional dam failure test model based on a mixed dam tailings pond in Yunnan Province based on the similarity theory and the self-invented hybrid dam construction method.Two dam failure model tests of the tailings pond under the condition of rain fall intensity of 80 mm/h were carried out.The changes of the dam failure process,inundation process and downstream impact were analyzed.The results showed that the development of the breach in the process of the tailings pond failure of mixed dam construction showed the characteristics of stages.The final breach of the two tests was located on the left bank.The downstream inundation range increased and tended to be stable with time,which was in line with the actual situation of the dam overtopping failure of the tailings pond.And the dam failure slurry caused different degrees of disaster impact on each sensitive point.The results of this study preliminarily revealed the evolution process of the dam overtopping failure of the mixed damming tailings pond,which provided reference value for the safety design and disaster risk management of tailings pond.The subsequent re search can further verify the engineering advantages of mixed damming through comparative tests.

Key words: tailings pond,dam overtopping failure,model test,mixed damming