Abstract: Combined with the decoupled Newmark method and the representative sliding surface,an efficient method for evaluating the dynamic safety performance of tailings dam is proposed. By accurately selecting the representative sliding surface and calculating its yield acceleration,combined with the response surface analysis,the analysis method of displacement prediction and dynamic failure probability of tailings dam is constructed. This method is applied to a case of an expansion tailings dam project in Yunnan Province. The most vulnerable areas in different expansion stages are accurately identified,and the permanent displacement and dynamic failure probability under earthquake action are calculated respectively. The calculation results show that the new reservoir area is expanded to the initial dam crest,and the old tailings dam is prone to deep damage. The expansion to the original tailings dam 1 / 2 high,the old and new dams are prone to shallow instability. To the top of the original dam,the new dam is easy to be damaged in shallow layer. The service period of the expansion dam is safe and meets the requirements of use. The case calculation results verify the accuracy and reliability of the method in engineering practice. 

Key words: dynamic stability of tailings dam,reliability analysis,Geostudio,Newmark method