The foundation soil in a certain channel of the Yangtze River Estuary is generally deep soft clay,which is prone to strength weakening under wave cyclic loadings,affecting the safety and stability of hydraulic structures.Static triaxial tests and dynamic triaxial tests under cyclic loading are conducted for three typical sections of soft clay in the channel of the Yangtze River Estuary.The strength and deformation weakening characteristics of the foundation soil under actual wave loadings are studied.The experimental results show that wave cyclic loadings have a significant impact on the strength and deformation characteristics of the undisturbed foundation soil in the channel of the Yangtze River Estuary.There is a clear weakening phenomenon in the strength and deformation parameters,The maximum deviatoric stress of the foundation soil in the undrained shear test decreases by 9% to 20%,the dynamic elastic modulus decreases by 5% to 14%,and the undrained shear line modulus Eu，1% decreases by up to 36%.The influence of foundation soil weakening needs to be considered during the operation of hydraulic structures.Through comparison,it is found that the consolidation process of foundation soil can significantly improve strength,reduce deformation,and reduce the impact of cyclic loading on strength weakening,thereby enhancing the bearing capacity of hydraulic structures' foundations.The research results can provide reference and basis for the design,construction,and resilience improvement of hydraulic structures in the channel of the Yangtze River Estuary.