[Geoqus] On Staged Construction of an earth structure

[bsaad at po-box.mcgill.ca]

I am simulating staged  construction of an earth dam. I built the whole 
model (using ONE PART ONLY) first and then removed all the layers 
except the foundation layer which is subject to initial stress.However 
during the first step ( which includes only applying initial stress to 
the foundation layer and  removal of the elements of the layers above 
)i have found that the elements of the removed layers which are at the 
interface of the base have deformed (still active). -do you think that 
i should use Surfaces and Tie Constraint between the foundation layer 
and the layer above to overcome this problem. If yes,
-As I have the model built in part only I am  facing a problem:  a 
partitioning line seperating the foundation from the layer above will 
not be recognized by ABAQUS as a surface. It seems that only the border 
lines of a part are recognized as surface, do you have any Idea if one 
can divide a parts into different parts :e.i can partitioning lines 
become  surfaces. or should I recreat the model from the begining
Thanks for help
Happy new year to all