Driven piles are often employed to support onshore and offshore structures at low-density, porous weak carbonate
chalk sites, which are encountered across Northern Europe and under the North and Baltic seas. Their efficient design is limited
by uncertainties regarding their ultimate axial capacity and load-displacement behaviour. Intensive axial testing has been under-
taken recently for the ALPACA Joint Industry Project on piles driven at a UK chalk site, in conjunction with comprehensive
chalk characterisation studies. This paper presents PLAXIS-2D numerical simulations of such piles' axial loading behaviour.
The simulation accounts for three distinct zones of chalk identified around the pile shafts after installation. These comprise a
thin annular zone of de-structured, puttified, chalk and a second, thicker, annular zone of highly fractured chalk; both have
different mechanical properties compared to the surrounding parent intact chalk mass. The FE analyses investigate how shaft
resistance, axial capacity and load-displacement behaviour develop differently in compression and tension tests.