Impedance of pile shafts under axial vibratory loads

This paper describes analytical solutions for assessing the axial dynamic response of the shaft of a pile subjected to vibratory loads, with particular reference to pile vibratory driving. Radial inhomogeneity arising from shear modulus degradation is accounted for by assuming continuous variations of the medium properties. This approach alleviates wave reflections from the interface between inner (nonlinear) and outer (linear) zones. Novel analytical solutions are presented for two cases describing the radial decrease of the soil modulus according to (a) a linear law and (b) a parabolic law. The results are evaluated over a wide range of parameters and compared with those obtained by a semi-analytical model derived from Michaelides et al. [14,15] and by a radial discrete model simulating the pile and soil movements from integration of the laws of motion (Hipervib-II model) (Holeyman [8]). © 2012 Elsevier Ltd.