Investigation of Mesh Independency of Micro Polar Constitutive Model by Modelling Saturated Porous Media in Biaxial Tests

摘要

Saturated porous materials can be abstractly simplified as homogeneous two phase media. In the two phase media, the displacements and micro rotations of skeleton particles as well as the pore pressure are assumed as basic unknowns in the finite element discretized equations. A coupled fluid-solid elastoplastic model has been implemented within the framework of micro-polar theory using ABAQUS which provides users an interface to define a new element (UEL) in this article. From the numerical simulated results of biaxial tests, it is shown that the nearly unique finite thickness of shear bands and similar load-displacement curves can be obtained regardless of different mesh sizes; larger rotations of particles in the shear band region are observed obviously, which can explain clearly the occurrence and development of shear bands; incompressible fluid in saturated porous material can affect significantly the peak load carrying capacity, at the same time the occurrence of shear bands is delayed compared with single solid phase media.