  The large-deformation mechanics and multiphysics of continuous or fracturing
partially saturated porous media under static and dynamic loads are significant
in engineering and science. This article is devoted to a computational coupled
large-deformation periporomechanics paradigm assuming passive air pressure for
modeling dynamic failure and fracturing in variably saturated porous media. The
coupled governing equations for bulk and fracture material points are
formulated in the current/deformed configuration through the updated
Lagrangian-Eulerian framework. It is hypothesized that the horizon of a mixed
material point remains spherical, and its neighbor points are determined in the
current configuration. As a significant contribution, the mixed
interface/phreatic material points near the phreatic line are explicitly
considered for modeling the transition from partial to full saturation (vice
versa) through the mixed peridynamic state concept. We have formulated the
coupled constitutive correspondence principle and stabilization scheme in the
updated Lagrangian-Eulerian framework for bulk and interface points. We
numerically implement the coupled large deformation periporomechanics through a
fully implicit fractional-step algorithm in time and a hybrid updated
Lagrangian-Eulerian meshfree method in space. Numerical examples are presented
to validate the implemented stabilized computational coupled large deformation
periporomechanics and demonstrate its efficacy and robustness in modeling
dynamic failure and fracturing in variably saturated porous media.
