Extension of a Current Continuum-Level Material Model for Soil into the Low-Density Discrete-Particle Regime

In this article, an attempt is made to construct a soil-material model which can be used over a wide range of soil densities. To construct such a model, an existing purely continuum-type soil material model (used in the high-density regime), within which the granular structure of the soil is neglected, is combined with an existing discrete-type soil material model (used in the low-density regime) within which soil is treated as an assembly of interacting particles. In order to enable it to be used in conventional transient, nonlinear dynamics, and finite element analyses, the new soil material model is cast using a continuum-type framework. Thus, while in the low-density regime soil behavior is fully dominated by the discrete-type soil-material model, soil has been treated as a continuum constituent properties of which are governed by particle geometrical parameters and particle-particle interaction laws. To demonstrate the utility and fidelity of the new soil material model, a series of uniaxial strain computational tests involving rectangular, parallelepiped-shaped soil-slug normal impact onto a rigid, fixed, flat surface is carried out. While these tests are of a one-dimensional character, they are generally considered as being representative of the loading and deformation histories experienced by mine-blast-ejected soil during its impact with the target structure. The results obtained using the newly proposed soil material model, in the low-density regime, are found to be fully consistent with their discrete-particle modeling and simulation counterparts, suggesting that the new model can be used in transient nonlinear dynamics, finite element simulations involving low-density soil.