Soil Mechanics: Problems with an Effective Stress Analysis in Abaqus

Hallo.

I'm modelling a sheet pile wall in a cohesion soil with groundwater level placed in the top of the model in Abaqus/Cae.  In this context I want to make an effective stress analysis. I have  establish my initial effective stresses and pore pressures in a Fortran subroutine. As my first step I have made a Geostatic step where the gravitation load is applied.  In the soil material I have specified a soil density of 19.9kN/m^3 and a specific weight of the wetting liquid of 9.82kN/m^3. Further I have specified the hydrostatic water pressure at the boundaries.  I'm using Pore fluid/stress elements.

Unfortunately, when I'm running the analysis my intial effective stresses from Fortran and the effective stresses in the geostatic step do not equilibrate when I'm looking at the vertical stress component in the visualization modul.

Have somebody an idea of what I'm making wrong? Is it the wrong type of elements I'm using or should I make another step than the geostatic step?

\Mads