Mechanical properties of granular materials: A variational approach to grain‐scale simulations

Abstract

SUMMARYThe mechanical properties of cohesionless granular materials are evaluated from grain-scale simulations. A three-dimensional pack of spherical grains is loaded by incremental displacements of its boundaries. The deformation is described as a sequence of equilibrium configurations. Each configuration is characterized by a minimum of the total potential energy. This minimum is computed using a modification of the conjugate gradient algorithm.Our simulations capture the nonlinear, path-dependent behavior of granular materials observed in experiments. Micromechanical analysis provides valuable insight into phenomena such as hysteresis, strain hardening and stress-induced anisotropy. Estimates of the effective bulk modulus, obtained with no adjustment of material parameters, are in agreement with published experimental data. The model is applied to evaluate the effects of hydrate dissociation in marine sediments. Weakening of the sediment is quantified as a reduction in the effective elastic moduli.

Frictional granular mechanics: A variational approach

“…The abundance of related applications and their large socioeconomic impact have motivated intensive research in the field of granular mechanics (see the references within [1,2]). Technical difficulties associated with grain-scale measurements, together with the shortcomings of continuum macroscopic models, make micromechanical simulations a prominent tool.…”

“…A computational technique to simulate deformation of a granular material and evaluate its mechanical properties, denoted hereafter as Quasi-Static Granular Model (QuSGM), has been presented in [1]. In QuSGM, a three-dimensional (3D) irregular pack of spherical grains is loaded by incremental displacement of its boundaries.…”

Digital Rock Studies of Tight Porous Media

“…so that the function v 0 does not depend on x and satisfies the boundary conditions (31). Then, Equations (33)-(34) take on the form…”

“…First, the coordinates of future grain centers have to be generated. We utilize the centers of a pack of spherical grains computed by simulation of compaction [31]. Second, the initial grain structures are generated by Voronoi tesselation [3,74].…”

Pore-Scale Study of the Impact of Fracture and Wettability on Two-Phase Flow Properties of Rock

“…The fractured medium for this study was computer-generated using QHull codes [3]. Holtzman et al [10] simulated compaction of a pack of spherical grains. The grain centers produced by this simulation were used to compute a Voronoi tessellation.…”