Abstract:Shapai RCC dam is a arch dam more than one hundred meters high

and it is one of the few examples withstood the earthquake

so the dynamic stability reanalysis of dam abutment is significant. Combining with the advantages of the finite element method and limit equilibrium method

the limit cumulative displacement formula is put forward and acted as the stability criterion of slider

dynamic stability analysis of Shapai arch dam’s abutment is conducted under two seismic waves and the overload study of Shapai arch dam is conducted under the artificial waves reflecting the 5.12 earthquake. The results show that Shapai arch dam’s abutment is stable under the impact of artificial waves (ah=2.05 m/s2)

which is consistent with the actual seismic effects. However

under the action of design waves（ah=5.31m/s2）

the Shapai arch dam’s left bank abutment is unstable

but on the right bank

the abutment keeps stable. When the left bank slider L1、L2 withstand the 3.2、3.6 times artificial wave respectively

the instability happens on the two sliders. The instability happens on the right bank slider when there is a 4.2 times overload. The slip direction and the influence of safety factor changing with time to cumulative displacement are considered. The abutment slider slip rule is reflected more practically and a new way of abutment dynamic stability analysis is provided in practical engineering.