Abstract: Taking tailing sand from Shenyang Hunnan Mining Corporation as raw materiel, the flume model tests on the piping mechanism were conducted to observe and analyze the mechanism and whole development processes from piping generation, developing, and dam failure in view of the foundation of tailings dam. The experimental results showed that piping failure occurred at the top of the weak permeable layer. Piping extends only to a limited area and will stop when hydraulic head is lower than the critical value. There, the piping is not connected with rivers. Otherwise, if hydraulic head exceeds the critical value, piping will propagate persistently towards rivers and the strong rush in piping finally results in failure of the whole foundation. Meanwhile, in the case of the change of foundation thickness, the law of seepage amount, sand ring diameter, piezometric head, piping breach time etc were respectively explored.

Key words: Tailings dam, Dam foundation, Piping, Model test