Balance the in-situ stress in CB-GEO

I want to balance the in-situ soil stress under gravity.
But the results are shown in the following figures.

It seems that the practicles at the bottom corners didn’t move verticly. I checked the boundaries conditions for several times but I don’t know what was worng.

I have solved this problem by seting damping cofficient from 0.75 to 0.05. It seems that a great damp cofficient will lead to this problem. Setting a small value works but I don’t know why.