Post-earthquake dynamic stability reanalysis of Shapai arch dam abutment

摘要

Shapai RCC dam is a 132 m high arch dam, and it is one of the few examples withstood great earthquakes, so it is significant to reanalyze the dynamic stability of dam abutment. A new way of abutment dynamic stability analysis method combining the advantages of finite element method and limit equilibrium method is proposed, and the limit cumulative displacement formula is put forward and acted as the stability criterion of sliders. 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 5.12 earthquake waves (a_h= 2.05 m/s~2), which is consistent with the actual seismic effects. However, under the action of design waves with 1% exceeding probability level in 100 years (a_h=5.31 m/s~2), the Shapai arch dam's left bank abutment is unstable, while on the right bank, the abutment keeps stable. When the left bank withstands the 3.2, 3.6 times artificial waves action, the instability happens on the left bank slider LI and L2 respectively. 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 presented new way of abutment dynamic stability analysis can not only reflect the influence of period when dynamic safety factor is less than 1.0, but also it duration time, and also the reverse sliding effect in the seismic action.