Abstract: This study simulates monotonic jacking processes of closed-ended and open-ended piles in sand using GeoTaichi, a self-developed GPU-accelerated domain decomposition coupled FEM-DEM multiscale platform. The methodology partitions the computational domain into DEM-controlled near-pile regions for soil-structure interaction and FEM-modeled far-field regions for enhanced efficiency. Contact model parameters for DEM and Mohr-Coulomb parameters for FEM were calibrated via simulated triaxial drained compression tests and experimental data. Validation against model chamber tests confirmed the reliability of coupled FEM-DEM in replicating pile tip resistance and radial stress distribution for closed-ended piles. Subsequent analyses of open-ended piles with different diameters revealed soil deformation patterns, plug length ratio (PLR), incremental filling ratio (IFR), and driving resistance evolution. Results demonstrate IFR's superior sensitivity over PLR in reflecting soil plug evolution, with internal plug friction trends aligning with IFR variations. This study offers an efficient numerical tool that enhances the understanding of pile-soil interaction mechanisms and aids in calculating the capacity of driven piles.