Large-Scale Discrete-Element Modeling for Engineering Analysis: Case Study for the Mobility Cone Penetrometer

This study aims to examine the use of the discrete-element method (DEM) for prototype-scale analyses of large discontinuous deformations. As an example, this paper presents the results of large-scale modeling of a mobility cone penetration test using DEM. The analysis demonstrates the potential for very-large-scale fully three-dimensional discrete-element computations for simulation of uniquely difficult geotechnical problems involving discontinuous deformation such as cone penetration, plowing, and slope stability. The particle-scale resolution was achieved using several million particles as a straightforward application of high-performance computing with message-passing interface (HPC-MPI) techniques. The use of the discrete-element method for micromechanical studies versus prototype-scale engineering studies are discussed in detail. The former involves accurately depicting details such as particle size distribution and particle shape; the latter uses the computational particles, similar to finite elements, where characteristics of the particles are simplified to gain computational efficiency. The DEM inherently captures qualitative constitutive soil behavior; calibration procedures are directed at achieving accurate quantitative behavior. A key issue is defining the soil's consolidation state because porosity cannot be specified as a material parameter but depends on particle placement and compaction. In addition to cone simulations in the near-surface environment, deep penetration simulations were used to examine the effect of confining stress on volume change. The cone tended to increase porosity at all stress levels, although the increase was significantly subdued by higher stress levels. The particle stress is presented in various formats to illustrate how cone resistance is developed. (C) 2019 American Society of Civil Engineers.