Scouring effect has a significant impact on the lateral vibration of caisson-piles composite foundation because of the change in stress history and the reduction of soils around the foundation. Based on the dynamic Winkler model proposed by author

a computational method of the dynamic impedance of caisson-piles composite foundation influenced by scouring effect with considering stress history is developed. Then sponge boundary dynamic FEM are used to validate the theoretical results. Finally

the proposed procedure is used to analyze a practical engineering. The results show that scouring effect has a significant impact on the dynamic stiffness and damping coefficient

and the more scour depth increased

the more remarkable influence on the results. This implies that it is not enough to only consider the loss of soil around the composite foundation for scouring effect

the change of stress history can further weaken bearing capacity of composite foundation and enlarge the dynamic response of structure

thus ignoring the change of stress history will result in an overestimate of value of dynamic impedance

and the change of stress history accompany with an apparent increase in amplitude of resonant response of composite foundation

while it has no effect on the value of resonant frequency.