A Mechanical Model for the investigation on the Vibro-drivability of Piles in Cohesionless Soils

A mechanical model based on the wave propagation method was developed to investigate the drivability of piles in granular soils. The soil resistance is divided into shaft and toe Resistance and its evolution is modelled by mathematical expressions, which are based on experimental results and justified from a soil mechanics point of view. The parameters of the model are estimated from impact penetration or vibro-penetration tests. The correct description of the toe resistance, which is essentially different from the toe resistance for static and impact penetration, was found to be the key for the modelling of vibrodriving. Considering the evolution of the vertical toe force and displacements during loop, two different penetration modes, called “cavitation” and “no-cavitation”, have been identified, depending on the set of machine parameters (frequency, static load and static moment) and on the initial state of the soil. It is shown that model is able to predict the occurrence of both penetration modes and the transition between them for different machine parameters.