Based on the similarity theory and the design data of Yangtianqing tailings impoundments of Yuxi Mining Co.

Ltd. in Yunnan province

a series of laboratory simulation model experiments of tailings dam-break surges with floating debris in different collapse forms (1/4

1/2 and the entire instantaneous collapse) were carried out in a uniform geometry flume of College of Resources and Environmental Science. The flow characteristics of slurry from tailings dam-break had be explored in the simulation model experiments. The experimental results show: (1) The collapse gate of tailings dam has an obvious influence on the impact stress

depth and evolution characteristics of slurry from tailings dam-break. (2) The slurry evolution course at the sections of downstream has an obvious attenuation phenomenon

and the slurry flows faster in the front

the depth and the impact stress vary along the long trail. (3) With the collapse gate augmenting

the impact stress and the slurry depth is increased obviously at a same section and the law of increase tendency is nonlinear. (4) The flow pattern of slurry has undergone great changes at the sharp bend flume; the vortex appears at the inner side and the reflection phenomena appear at the outside

the vortex and reflection phenomenon in entire instantaneous collapse condition are greater obviously than which of 1/2 and 1/4 instantaneous dam-break. (5) The time of the front slurry arriving at a same section of downstream in entire instantaneous collapse condition is far less than that of 1/2 and 1/4 instantaneous collapse conditions. With the collapse gate diminishing

the peak of impact stress is weakened and the time that the impact stress gets to the peak value is delayed. The results can provide some references to study of the characteristics of slurry flow in different collapse gates deeply and there is an important real significance to conduct the mine enterprises to take some corresponding actions to prevent and control the disaster of tailings dam-break.