Discrete-element modelling of pile penetration to reveal influence of soil characteristics

Abstract

Soil response to pile penetration has both macro- and micro-mechanical aspects. At both scales, the properties of the particles and their interactions with each other control behaviour. Unfortunately, examination of particle-scale effects during penetration is not possible with either physical modelling or using continuum-based numerical models. The discrete-element method provides a powerful medium for modelling soils as particulate materials and can be used to investigate pile–soil interaction. However, such models are computationally demanding and need extensive optimisation, which in turn requires an understanding of the influences of soil characteristics on the mechanics. For this purpose, a series of pile penetration models was designed using three-dimensional discrete-element models. Structural parameters such as model dimensions and pile properties were kept constant while the soil characteristics were varied one at a time. This allowed uncoupled observation of the influences of individual soil characteristics including stiffness, inter-particle friction, rolling friction, average size, shape, packing density and grain size distribution. The results are presented in graphical form and their implications with respect to modelling are discussed.