Due to the randomness of dynamic loads and structural parameters

dynamic reliability of stability between layers of RCC gravity dam deserves the attention. Considering the randomness of spectrum characteristics and peak acceleration of seismic waves as well as material parameters of the dam

potential sliding paths of the dam subjected to earthquake can be identified by generalized statistics; based on stochastic finite element method (SFEM) results

the limit state function of dynamic sliding is built according to rigid limit state criteria and response surface method (RSM) under a certain seismic loading; the reliability index is got as well; then

considering the relativity between different failure paths

the reliability index of the system can be estimated by Ditlevsen narrow-bound method. Finally

the randomness of seismic load is taken into account

the numerical integration method based on complete probability formula is used to get the dynamic system reliability. The results indicate that the system reliability between layers of gravity dam no longer depends on the failure path of the foundation plane

but is closely related to the failure paths at the downstream fold slope when the horizontal earthquake coefficient is greater than 0.2. This method is mathematically clear and practical.