I have a question on safety calculation in PLAXIS 2D. I used safety calculation in PLAXIS to check the overall stability of retaining wall and got a very low Msf value. By checking the results, a local failure occurred on the ground surface, for example the edge of surcharge. Besides a higher FoS is achieved at the intermediate calculation steps, but then declined to a lower values. The mesh quality is very good at the area surcharge applied. So I don't think it is due to a mesh quality issue. Is there any way to avoid such local failure in the safety calculation?