Numerical study of anisotropic permeability effects on undrained CPTu penetration

The numerical simulation of Cone Penetration Tests (CPT) is a challenging field
in geotechnics. Both the underlying physical model and the numerical method need to be capable of
taking into account large deformations and displacements within the problem domain. Researchers at
the Polytechnic University of Catalonia (UPC) and the International Center for Numerical Methods in
Engineering (CIMNE) have developed a Particle Finite Element Method (PFEM) code named G-PFEM
which conducts fully coupled analysis of penetration problems in saturated porous media. An updated
Lagrangian description is used in order to formulate the governing equations. The PFEM is based on
frequent remeshing of critical regions of the problem domain adding additional computational cost to the
solving process. Therefore, the use of linear elements in combination with a stabilized mixed formulation
of the governing equations helps to reduce the computational effort and at the same time cope with the
phenomenon of volumetric locking associated with linear elements. Within the present work, anisotropic
permeability is introduced and tested by means of consolidation of an elastic soil layer. Furthermore,
recalculations of an available in-situ CPT are performed allowing the examination of the influence of
changing boundary conditions, such as anisotropic permeability of the soil or penetration velocity of the
cone, on the measured tip resistance, sleeve friction and pore water pressure. It was found that the recalcu-
lation with G-PFEM provides comparable results for undrained conditions and anisotropic permeability.