基于分域耦合FEM-DEM多尺度方法的砂土中闭口和开口桩沉桩过程模拟 English Version
Simulation of closed- and open-ended pile installation in sand using a domain-decomposition coupled FEM-DEM multiscale approach
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摘要: 本文基于自主开发的GPU加速三维分域耦合有限元-离散元（FEM-DEM）多尺度计算平台GeoTaichi，模拟了砂土中闭口和开口桩的单调静压沉桩过程。该方法将求解域分为紧邻结构物的区域和远离结构物的区域，分别使用DEM模拟砂土与桩的相互作用；以及FEM模拟远离桩的区域，提高计算效率。通过模拟三轴排水压缩试验并结合试验数据，确定了DEM域的接触模型参数和FEM域的摩尔-库伦本构模型参数。闭口桩模拟获得的桩端阻力和砂土中的径向应力分布与文献中模型槽试验结果一致，验证了耦合FEM-DEM方法模拟打入桩静压沉桩过程的可靠性。随后，分析了两种不同管径的开口桩沉桩过程中桩周土体变形，土塞率（PLR）、土塞增长率（IFR）以及沉桩阻力的变化，得出IFR相对于PLR在反映土塞状态变化方面更为敏感，且土塞内壁摩阻力的发挥趋势与IFR的变化趋势一致。研究为揭示沉桩过程中的桩土作用机理及合理预测打入桩承载力提供高效的数值计算工具。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.
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Keywords:
- domain-decomposition /
- FEM-DEM /
- pile installation /
- pile-soil interaction /
- GeoTaichi
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