Mesoscale Validation of Simplifying Assumptions for Modeling the Plastic Deformation of Fluid-Saturated Porous Material

Abstract

Mesoscale simulation of fluid-saturated porous materials is used to investigate unvalidated assumptions in continuum modeling of geomaterials at high rates. The importance of pressure-dependence of the matrix material on the applicability of the effective-stress approach during plastic deformation is explored. The hydrostatic load-unload response of saturated porous structures having both pressure-dependent and pressure-independent matrix materials is modeled using the material point method. Results are used to validate a semi-empirical strain-to-yield effective-stress model in which the pore pressure evolves with local material deformation, an approach that is applicable to materials with closed porosity or those loaded at sufficiently high rates that fluid transport can be neglected. Mesoscale simulations are used to estimate the strain rates beyond which fluid flow through the matrix can be neglected.