Étude du comportement des matériaux granulaires sous sollicitation cyclique

DEM simulations modeled particle shapes using spheres with rolling resistance and clumps of spheres. Model parameters were calibrated using monotonic drained triaxial tests on Fontainebleau NE34 sand. Cyclic triaxial tests then evaluated the evolution of Young’s modulus (E) and damping ratio (D) with strain amplitude at varying density indices (ID), linking macroscopic behavior to grain-scale interactions and energy dissipation. Small-scale laboratory tests examined the behavior of cylindrical intruders in sand, considering factors such as relative density, installationvelocity, intruder size, and depth. Moreover, centrifuge experiments at a 1/25 scale simulated "quasi-2D pile" installation in medium dense sand, with Particle Image Velocimetry (PIV) analysis of the displacement and deformation fields. Numerical simulations complemented the experiments by studying the micromechanical behavior of sand during pile installation. The calibrated DEM model analyzed different jacking techniques, focusing on stress distribution, particle displacement, mobilized friction, porosity, and the effect of installation speed.