Hello @everyone, @itascan
I hope you are doing well. I am working on an MSE wall model in FLAC3D and I am facing several problems when extracting geogrid tensile force and tensile stress at selected coordinates.
Model Summary (very short)
My model is a 3D MSE wall: H = L = W = 6.4 m.
I used 10 geogrid layers, each with length 5.9 m (from x = 0.5 to x = 6.4).
For each geogrid, I want to extract tensile force and tensile stress at 16 points along the length with equal spacing 0.3933 m, all at y = 3.2.
The geogrid mesh is size (40,4), giving an element length of 0.1475 m, which should be fine enough to give different values at each point.
To extract force and stress, I used:
structure geogrid history resultant-nx position (x,3.2,z) surface-x (1,0,0)
structure geogrid history stress-xx position (x,3.2,z) depth-factor 0
Problems I am facing
-
Values are much smaller than theoretical
Even with correct coordinates, the extracted tensile force (resultant-nx) and tensile stress (stress-xx) are far lower than what I get from FHWA theory. -
Some points show negative tensile force/stress
A few of the first x-points show negative values, even though tension should always be positive for geogrids. -
Every 4 consecutive points give the same value
Even though I used a fine mesh (5.9/40 = 0.1475 m element size), FLAC3D gives repeated identical values for blocks of 4 points.
I attached a graph that shows how points 1–4 are identical, 5–8 identical, 9–12 identical, and 13–16 identical. -
History plots sometimes do not appear
Many times the model runs but FLAC3D shows no history curves.
Only after running the model 2–3 times the curves appear.
This is happening very often. -
Are my commands even the right ones?
I am not fully sure if the below commands are the correct choices to obtain **geogrid tensile force per unit length** and **axial tensile stress** at a specific point along the geogrid. If these are not the correct commands for my case, could you please suggest the proper command(s) and options I should use?
structure geogrid history resultant-nx position (x,3.2,z) surface-x (1,0,0)
structure geogrid history stress-xx position (x,3.2,z) depth-factor 0
Thank you very much