I modeled a 23-ft-high MSE wall with two uniform surcharge loads of 3000 psf and 1000 psf applied at the top. To verify the stress outputs, I queried the vertical stress at a depth of 26 ft (3 ft below the wall base). Based on basic calculations, the vertical stress should be at least 2860 psf (using a unit weight of 110 pcf, 110×26=2860).
However, my model results are significantly lower, ranging between 800 psf and 2100 psf, which is unexpected.
I suspect the issue might be related to the liner parameters in the wall model, specifically:
Coupling stiffness
Coupling cohesion
Coupling friction angle
I estimated the coupling stiffness using the method recommended in the FLAC manual, but even when varying these values, the stress results remained mostly unchanged.
To double-check, I used another numerical modeling software to simulate the same problem, and the stress values exceeded 2860 psf, aligning with the expected calculation.
What could be causing this discrepancy in my original model?
Hello @Adams,
It could be many things. My initial guesses are the model has not equilibrated under gravitational loading and you don’t get the vertical stresses you expect. I would check this by running the model without the structural elements and see if you get the expected stresses.
Thank you for your suggestion. I reviewed the line of code and ensured I used “model gravity” and “zone initialize stress”. Then I calculated averagely the vertical stress at the base of the model and compared it with the maximum stress from FLAC, which was quite similar. However, the model still does not give a reasonable stress output when I remove all the structural elements and query at that location of interest. Please, what else could you suggest I use to trouble shoot the issue?
