Because of its high strength

great bearing capacity and fine durability

pile foundation has been widely used in civil construction engineering such as high buildings

large workshops

water and electricity hinges

railways

highroads

bridges

offshore platforms and nuclear power plants. The study on lateral dynamic response characteristics of pile can be sorted into three classes such as elastic continuum methods

beam-on-Winkler foundation methods and numerical methods. Also Tajimi and Novak have reviewed the research advancement of pile dynamics and proposed many questions to be solved. In this paper

a computational method and mechanical model for evaluating lateral dynamic response of single pile embedded in non-homogeneous soil layers to harmonic excitation are established based on a certain assumptions and the improved dynamic model of beam-on-Winkler foundation by using the principle of soil dynamics and structural dynamics. Both non-homogeneity of soil strata and softening effect of soil layer around pile during vibration are simultaneously taken into account in the proposed computational model. Then the comparative study on a numerical example is carried out and the research results indicate that the numerical results of dynamic response of single pile computed by the proposed method are rather rational and can well agree with the numerical solutions gained from the well-known software of finite element method. Finally the parametric studies are conducted for a varied range of main parameters and the following effects of relevant factors on lateral dynamic response characteristics of single pile embedded in non-homogeneous layered soils to harmonic loading with different exciting frequencies are discussed. 1.The lateral displacement of single pile is increasing gradually along with the enhancement of the softening area and the softening degree of soils around pile. 2.The lateral displacement of single pile is influenced by the conditions of soil layers and the influence of upper soil layer is greater than that of the bottom soil layer. So much attention must be paid to the engineering characteristics of upper soil layer in the design and analysis of the lateral dynamic response of pile. 3.The lateral displacement of single pile is not always reduced monotonously along with the increase of slenderness ratio of pile and there is an optimal slenderness ratio. In the illustrated example

the optimal slenderness ratio is 20. 4.The lateral dynamic response of single pile takes on the trend of increase along with the increase of the pile-soil stiffness ratio.In conclusion

the computational method and mechanical model proposed in this paper for evaluating the lateral dynamic response of single pile is rather rational and can be used in the analysis of pile dynamics.