Vertical vibration of piles in viscoelastic non-uniform soil overlying a rigid base

This paper presents an analytical methodology that provides the dynamic response of an elastic pile embedded in viscoelastic non-uniform soil overlying a rigid base, when subjected to a harmonic vertical load. The non-uniform soil comprises two parts, featuring independent properties: the substratum soil, below the pile toe, is represented by a viscoelastic layer of finite thickness resting on rigid bedrock, while the soil surrounding the pile shaft is modelled as a series of infinitesimally thin independent viscoelastic layers. Following validation of the methodology, where we show that the presented solution degenerates to published solutions for simpler pile embedment conditions, we use results of a parametric investigation to discuss the mechanisms governing the dynamic response of the non-uniform soil-pile system. The presented solution allows modelling realistically the contribution of end-bearing resistance to vertical vibrations of piles in cases of practical interest when non-linearity effects can be effectively ignored.