DEM simulation of cone penetration tests in sand in a virtual calibration chamber

In this paper, cone penetration tests (CPT) in a virtual calibration chamber (VCC) were simulated using the discrete element method (DEM) to investigate the factors influencing the cone penetration tip resistance (q_c) in sand. The microscopic parameters of the Fontainebleau sand were calibrated by comparing the simulated macroscopic mechanical behavior to that from experimental drained triaxial tests. The influences of VCC dimensions and prescribed boundary conditions, penetration rate, and confining stress on the q_c were investigated. The results show that the q_c under different boundary conditions converges as the diameter of the VCC increases. It is recommended that a ratio of chamber diameter to cone diameter larger than 20 should be used to eliminate the potential boundary effects for CPT in VCC for samples of different relative density (D_r). The comparison between the numerical simulations and cavity expansion theory predictions presents significant relationships among critical state parameters (Ψ_cri), peak internal friction angle (φ_peak) and normalized cone tip resistance (Q).