Numerical Soil Mechanics Experiments using Discontinuous Deformation Analysis

In this study, several basic experiments from Soil Mechanics applied to granular materials have been simulated numerically: i) Confined Compression, ii) Simple Shear, iii) Sedimentation. Granular materials present an internal discontinuous structure, for which the numerical method DDA (Discontinuous Deformation Analysis), which belongs to the family of Discrete Methods, has been used due to its ability to model the mechanical behavior of media whose behavior is similar to that of granulars.

The stress-strain relations of two representative granular samples taken from the literature (experiments i) and ii)) have been simulated by a high number of rigid circular disks of different sizes. These relations reflect the classical behavior of the sand, including the peak resistance common in compacted samples. However, other characteristics such as the softening after the peak cannot yet be perfectly simulated, given the current absence of a nonlinear law for the friction coefficient and/or of the locking and unlocking capability of polygon-shaped particles.

The third experiment consists of the numerical computation of a grain size distribution curve with the Sedimentation test. To achieve this, the basic laws of Fluid Mechanics (hydrostatic thrust and Stokes’ law) are implemented in DDA. In the experimental reality of this experiment, there are interactions through contacts among particles that change the real grain size distribution of the sample. DDA is able to duplicate these changes, and this characteristic of the sedimentation experiment is well simulated.