Analytical solutions for vertical piles embedded in a two-layer soil system and subjected to lateral loads were carried out. The pile was regarded as a vertical elastic foundation beam; and then based on the basic concept of the Winkler elastic beam theory

the governing differential equation in terms of pile lateral deflection and its relative semi-analytical solutions by using the power series method were proposed. By considering the deflections and forces continuum conditions along the pile length

a matrix form of pile response at any depth was expressed through the deflections and lateral forces at the pile head. Moreover

the results obtained from the proposed solutions are compared with the results obtained from the simplified calculation solutions suggested by the “Chinese code for design of ground base and foundation of highway bridges and culverts”. The comparative results indicate that when the height of the first soil layer is in the range of some value

the results from these two methods are consistent with each other. Otherwise

there is a difference between the results from these two methods.