Performance of Monotonic Pile Penetration in Sand: Model Test and DEM Simulation

By integrating laboratory tests and three-dimensional discrete element methods, this research extensively explores the macroscopic and microscopic mechanisms of static pile penetration in standard sand. Initially, the mesoscopic parameters of standard sand were established via flexible triaxial compression tests, and a three-dimensional discrete element model was created using the particle size magnification technique. The study results confirm the rationality of parameter selection and numerical modeling by comparing penetration resistance and displacement obtained from laboratory model tests and discrete element simulations. Initially, penetration resistance swiftly increases, then stabilizes progressively with increasing depth. The lateral friction resistance grows with penetration depth, especially peaking near the cone tip. Moreover, horizontal stress quickly rises during pile penetration, mainly caused by the pile foundation compressing the adjacent soil particles. Displacement of the foundation particles is primarily focused around the pile side and cone tip, affecting an area roughly twice the pile diameter. Soil particle displacement exhibits a pronounced vertical downward movement, primarily driven by lateral friction. The distribution of force chains among foundation particles indicates that the primary stressed areas are at the pile ends, highlighting stress concentration features. This research offers significant insights into the mechanical behaviors and soil responses during pile foundation penetration.