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This paper presents a distinct-element method study of the dynamic behaviour of a rigid bored monopile for an offshore wind turbine foundation subject to force-controlled cyclic lateral loads. A two-dimensional model of a granular assembly was developed using the particle flow code. The model was consolidated under high gravity to simulate existing centrifuge model tests. The simulation results showed great similarity to the published experimental measurements in terms of the relationship between loading and the normalised lateral displacement. The dependency of the accumulated rotation, lateral deflection and stiffness on the two key loading characteristics, loading magnitude and direction, were analysed. Particle-scale information was employed to reveal the micromechanics of these dynamic behaviours. It was seen that relative particle displacement fields provided clear micro-scale evidence of the development of shear zones induced by the lateral cyclic loading of the pile. Meanwhile, local void densification was also observed through particle movements.

This paper presents a two-dimensional Particle Flow Code (PFC2D) model of the Discrete Element Method (DEM) that is used to study the effects of pile installation in deep foundation. It is accepted widely that installation method affects pile behaviour, but there are still limited studies that compare and analyse the impacts systematically. In this paper, the DEM is used to explain the pile behaviour installed in granular soils. A rigid bored pile and a rigid driven pile of the same geometry were installed into an assembly of granular soil modelled under a high gravitation force. Behaviour of the driven pile during penetration compares well with published data, and the numerical data also provides further insights of the soil-pile interaction during the penetration process. After pile installation, comparisons of the subsequent pile-loading behaviour were made, showing different contributions of shaft and end bearing resistance between the bored pile and the driven pile. Furthermore, the impacts of having different pile weights and different soil friction angles were discussed. When considering the same pile and soil friction, the driven pile performed better in the pile load test because the soil was compressed during the driving process. In particular, it was found that the soil friction affects the bored pile and the driven pile in a different manner such that soil friction will take effect after certain depth for bored pile, however, it will have an impact at the beginning for driven pile. Micro-scale sliding fraction of the particles near the two piles was also used to