Three-dimensional DEM simulation of plugging behaviour of smalldiameter open-ended model piles penetrating into sand

It is known that plugging behaviour plays a significant role in affecting the bearing capacity of open-ended piles driven in sands. However, numerical analyses of pile plugging presents multiple challenges. To better understand plugging development during open-ended pile installation, three-dimensional discrete element method (DEM) simulations have been undertaken of small model piles' penetration in virtual calibration chamber tests. The analyses employed the open-source MUSEN framework and took advantages of graphics processing unit (GPU) acceleration, particle refinement and axisymmetric modelling. The simulation was able to reproduce pile plugging behaviour in sands ranging from fully coring to fully plugged states. The contributions to pile capacity of internal and external shaft friction are correlated with plug indices including incremental filling ratio (IFR) and plug length ratio (PLR). The new, purely theoretical, analyses show shaft resistances that agree well with estimates made from well-known CPT-based offshore design methods. The poorer agreement found for base resistances also identified ways in which the new DEM analyses may be improved.