Numerical Modeling of Cone Penetration Test: An LBM-DEM Approach

In this paper, the discrete element method (DEM) is coupled with the Lattice Boltzmann method (LBM) to model the cone penetration test (CPT) of a saturated granular media. The coupled numerical model was calibrated using one-dimensional (1D) consolidation theory. The results obtained from the 1D consolidation test simulation showed good agreement with the analytical equation that was proposed by Terzaghi. A series of LBM-DEM simulations were carried out to understand the effect of the penetration rate on the behavior of saturated granular materials during the CPT. The model has predicted a significant influence on the excess pore fluid pressure (Delta u) and an insignificant influence on the cone resistance responses (q(t)) and has qualitatively captured the effect of penetration rate, which was consistent with the experimental data. The simulation results showed that Delta u increased with an increase in the penetration rate. The particle displacement and fluid velocity (U) contours have provided insights into the particle behavior and fluid pressure fluctuations during CPTs. The increase in Delta u was attributed to the fluid pressure gradients that were created by the cone in the fluid system based on the penetration rate. The pore pressure distribution plots have shown a maximum pore fluid pressure below the cone region and over the cone shoulder position. A consistent evolution pattern of fabric anisotropy has been observed throughout the depth (z) under all the penetration rate conditions. The fabric components (circle divide(22)) and (circle divide(11)) have dominated around the cone area and at the boundary region, respectively. This indicates the preferential orientation of contacts in the vertical direction at the cone region and the horizontal direction at the boundary region. The simulation results have demonstrated that the LBM-DEM model can efficiently simulate the CPT and associated pore fluid pressure, which included the cone-particle-fluid interactions during CPTs. (C) 2022 American Society of Civil Engineers.