Mechanisms governing the sand plug behavior inside an open-ended pile are examined using the discrete element method. A series of numerical pile penetration tests have been conducted by considering the influence of soil density, pile geometry and installation method. A novel sample generation method, based on the replication of unit cell, is applied to produce a large and homogeneous sample efficiently. According to the soil deformation pattern, a “nose cone”, with the length about one pile diameter, has been observed beneath the small diameter jacked pile at the end of penetration. Plugging effect is shown to be more prevalent for jacked piles than dynamic installed piles. Also, larger penetration, smaller diameter and higher soil density all seem to promote plug formation, while the influence of wall thickness is not that obvious. This conclusion is later verified by the development of Incremental Filling Ratio (IFR) and porosity distribution. Furthermore, remarkable stress concentration has been observed at the lower part of the soil plug. The development of installation resistance indicates that jacking produces the largest resistance while dynamic installation methods ease pile penetration. Further analysis based on particle movements, contact force chain distribution and stress orientation provides a micromechanical perspective of the plug behavior. Finally, the plug resistance mobilization process at different plugging conditions and the formation process for soil plug are illustrated.

使用离散元方法研究了控制开放式桩内塞沙行为的机制。考虑到土壤密度，桩的几何形状和安装方法的影响，进行了一系列的数值桩穿透试验。一种基于单位细胞复制的新型样品生成方法被应用于有效地生产大而均匀的样品。根据土壤变形模式，在穿透结束时，在小直径顶桩下方观察到一个长度约为一个桩直径的“鼻锥”。结果表明，与动力安装桩相比，顶拔桩的堵漏效应更为普遍。而且，更大的穿透力，更小的直径和更高的土壤密度似乎都促进了堵塞的形成，而壁厚的影响并不那么明显。后来通过增量填充率（IFR）和孔隙率分布的发展验证了这一结论。此外，在土塞的下部观察到显着的应力集中。安装阻力的发展表明，顶升产生最大的阻力，而动态安装方法可减轻桩的渗透。基于粒子运动，接触力链分布和应力方向的进一步分析提供了插头行为的微观力学视角。最后，说明了在不同堵塞条件下的堵塞阻力动员过程和土壤堵塞的形成过程。在土塞的下部观察到明显的应力集中。安装阻力的发展表明，顶升产生最大的阻力，而动态安装方法可减轻桩的渗透。基于粒子运动，接触力链分布和应力方向的进一步分析提供了插头行为的微观力学视角。最后，说明了在不同堵塞条件下的堵塞阻力动员过程和土壤堵塞的形成过程。在土塞的下部观察到明显的应力集中。安装阻力的发展表明，顶升产生最大的阻力，而动态安装方法可减轻桩的渗透。基于粒子运动，接触力链分布和应力方向的进一步分析提供了插头行为的微观力学视角。最后，说明了在不同堵塞条件下的堵塞阻力动员过程和土壤堵塞的形成过程。接触力链分布和应力方向提供了插头行为的微观力学视角。最后，说明了在不同堵塞条件下的堵塞阻力动员过程和土壤堵塞的形成过程。接触力链分布和应力方向提供了插头行为的微观力学视角。最后，说明了在不同堵塞条件下的堵塞阻力动员过程和土壤堵塞的形成过程。