ABAQUS: Trouble getting VUFIELD subroutine to work

Hi all,

 This is my first post on iMechanica. I'm a student at UC Davis working on my master's project which is a FEM analysis of a bridge footing. I've scoured the web, read and reread the Abaqus Documentation, and tried trial and error for a couple weeks on a problem, to no avail. Here's the issue:

I'm trying to model varying soil elasticity (and other Mohr-Coulomb data) as a function of soil depth from values I extrapolated from an actual geotechnical report. Under materials, and have 1 field variable, and it is listed as depth from surface. I'm trying to get the VUFIELD subroutine to work in Abaqus CAE/Explicit to vary the elasticity throughout the soil profile. I have gotten this to work with Abaqus/Standard CAE but the Explicit formulation has been difficult to implement. Under the step keyword in the input deck, i have included *field,user, followed by the model nodes calebset. In the VUFIELD subroutine, I have pulled the VUFIELD subroutine straight from the Abaqus documentation, and have added:       FIELD(NBLOCK,NCOMP,NFIELD)=COORDS(2,NBLOCK), where the number 2 is the y-coordinates, as I want the soil to vary with respect to the global y-axis. 

I believe I have specified the nodes correctly and the subroutine compiles without errors, but when I verify the varying modulus of elasticity (by looking at the varying strain under a quasi-constant load), the material appears to be a constant modulus of elasticity, of the first entry in the elasticity material properties.

 I have attached the VUFIELD subroutine and the input file. Note the input file extension will need to be changed to .inp and the vufield extension needs to be changed to .for (website won't let me upload original files with their file extensions). Hopefully this is a simple fix. I appreciate the help in advance.

 Regards,

Caleb