Abstract: The change of the soils around pile affected by scour is one of the major causes for the failure of structure of the partially-embedded single pile. The soil fields in engineering are mostly layered, and the research on the mechanical characteristics of pile foundation in layered soils has attracted increasing attention. In order to accurately reveal the effect of scour on the dynamic response of the partially-embedded single pile in layered soils, a dynamic model of the laterally loaded single pile in layered soils is established by employing Hamilton’s principle based on the modified Vlasov foundation model. Then, the finite difference method is used to solve the natural frequencies of the single pile affected by scour, and to achieve accurate modeling of the soil-structure interaction (SSI) system affected by scour. Analytical solution of the forced vibration of the single pile is obtained by Green’s function method. The effects of physical characteristics of the layered soils on the dynamic response of the partially-embedded single pile are studied by numerical calculation and parameter analysis. The results show that the dynamic model of the partially-embedded single pile in layered soils based on the modified Vlaosv foundation model can accurately predict the impact of scour on its dynamic characteristics. As the scour degree intensifies, the first-order natural frequencies of the single pile in layered soils decrease significantly, and the subgrade reaction coefficient of each layer of soils in the improved Vlasov foundation model decreases, and the shear coefficient increases. When the length of the non-embedded section of the pile satisfies ( is the pile length), the lateral instability of the partially embedded single pile is observed under the dynamic load. As the thickness of the underlying soil increases, the first-order natural frequencies of the single pile at each scour level increase. As the elastic modulus of the first layer of soil increases by about 0.43 times, 1.14 times, and 1.86 times, the first-order natural frequencies of the single pile at the scour level of 0 increase by about 8.9%, 19.5%, and 27.1%.

Key words: partially-embedded single pile, layered soils, modified Vlasov foundation model, scour effect, finite difference method, Green’s function method