membrane elements (modelling geogrids)

[anna12]

Hallo,

I am trying to model a piled embankment reinforced with geogrids (geogrids behave like membranes).
I made a 2D and a 3D model.
I know that my results (displacement/settlements on the top edge) without geogrids are correct.
So I know, that I am modelling the geogrids wrongly but I have no idea what I should change in the model.
My geogrids do not influence my system decisive. I am getting circa the same results as without geogrids.

PLEASE HELP ME!!!!!!!!!!!



Data of the geogrids I used in ABAQUS:

2D- Model:
elements:
T2D3: (A 3-node quadratic 2-D truss)
and
T2D2: (A 2-node linear 2-D truss)
Cross sectional area = 0.0008 m
(I also tried it with plain strain elements, but the results are circa the same.)
material:
elastic (bulk modulus and Poisson´s ratio) and *no compression

3D- Model:
elements:
M3D8R: (An 8-node quadrilateral membrane, reduced integration)
and
M3D4: (A 4-node quadrilateral membrane)
thickness = 0.0008 m
material:
elastic (bulk modulus and Poisson´s ratio) and *no compression

Interaction Properties same in 2D and 3D –model):
Tangential behaviour: Friction coefficient
Normal behaviour: Hard Contact