Steady state analysis convergence problem: error 101

Hello, I hope you are doing well.

I am modelling a steady state groundwater condition for a simple slope and I am having an error 101, in which the soil body seems to collapse. My intention is to use the pore pressures from this analysis in a subsequent safety calculation to obtain a SSR value.

For this model I defined a head boundary condition in the upper and lower side of the slope, as well as a seepage boundary condition in the slope face (see image above). When performing the calculation I am getting no convergence, with a Mstage multiplier of 0,36 for the phase, and not going forward from that value (see image below).

To solve this issue I decided to change the hydraulic parameters by having a higher permeability soil (I went from 1e-4 m/s to 1e-2 m/s), however my problem was still persistent. Then I decided to increase the "Max unloading steps" in the numerical control parameters (from 5 to 30), and I got little improvement, but not good enough to achieve a convergence. I am curious about this situation because I think this model is not so diificult to solve. As a checking process, I modelled the same situation in SEEP/W in GeoStudio and no issues were found. I also think that an energy head loss of 20 m is too large for the model, and I have checked the magntude of the gradients which also think are not to large.

Is there something I am not considering or seeing for my model? Is it an honest error from the software since I am obtaining the flow from a plastic analysis and a failure must be presented in the soil? Can this be prevented just by a mere change in some of the model inputs or parameters? I have obtained a solution using a drain toe (where I get convergence), however I just want to see this simple situation for the slope being modelled.

Thank you for your time. I hope I made myself clear.

Regards,

JuanP