Pile setup is now generally recognized as a characteristic feature of displacement pile axial response in sand. However, a clear understanding of the phenomena underlying pile setup is still missing because reliable and practical methodologies to study the problem are lacking. It is very difficult to measure and control all possible contributing factors in field testing experiments, whereas physical laboratory tests often fail to replicate field observations. The resulting ambiguities undermine proposals to incorporate setup in design procedures. A new methodology to study pile setup based on the discrete-element method (DEM) is proposed here. We build a virtual centrifuge chamber using a granular material DEM model calibrated to represent Fontainebleau sand, a quartz sand. The DEM material model, which incorporates delayed grain fracture, was previously verified by reproducing creep and relaxation in element tests, but relies on much simpler measurements for material calibration. Model piles are installed in the chamber by jacking, performing long (up to 1 month) creep stages and measuring shaft resistance at regular intervals by means of pullout tests. The simulated pile creep and pullout responses were well-aligned with previous experimental observations. The simulations presented strongly support the hypothesis that delayed grain fracture is a significant contributor to pile setup. The methodology presented opens the way to quantify this and other physically based explanations of pile setup and creep.

In situ soil characterization often involves penetration tests. The response to both static and dynamic penetration in volcanic sands is known to be controlled by particle crushing, obscuring the effect of density and confinement on the response. This severely limits the use of penetration tests for soil characterization. In this work a virtual calibration chamber (VCC) built using the discrete element method (DEM) is employed to explore the relationship between cone penetration tests CPTs (static) and standard penetration tests SPTs (dynamic) results on a volcanic sand. The simulated CPT results are shown to capture well experiments from the literature over a range of density and confining stress. The comparison between the simulated CPT and SPT results shows good agreement with empirical expressions based on particle size. It was found that energy-based equivalent dynamic tip resistance obtained from the SPT is a good match for static cone tip resistance if shaft resistance effects are discounted. The results presented confirm the potential of DEM based VCC to examine the performance of in-situ tests in complex soil conditions.