Please help: Stiffness matrix is nearly singular and cannot be solved [error code: 20] in PLAXIS 3D. Can anyone help me to fix this file ? File Link: drive.google.com/.../view
Dear Santosh Katuwal,
According to the Reference manual, there are some possible reasons for error #20:
In the last PLAXIS 3D CE V21.01 version I have error #204, the reasons are almost the same.
Bad mesh quality
The first possible reason is bad mesh quality. In your project minimum mesh quailty is ~9×10^−9:
It is a very-very small quality. The worst elements are:
I recommend to correct geometry in these areas.
For example, there are different Y coordinates in the vertical plate:
I suppose there are geometric collisions in this small volume (and common polygons):
If we use checkgeometry command we can find a lot of other problems with geometry.
Also I should notice that you switch off standart Enhanced mesh refinements option and increase coarseness factor to soil volumes. In my humble opinion, it is not a good idea, because in the most cases standart options (by default) give us the optimal variant.
Large stiffness differences
The second possible reason for error #20 is large stiffness differences. As far as I can see there is no big differences between the smallest and the biggest stiffnesses in the model. So I think the main problem is mesh quality.
Others
I do not mention other issues: activated basement on Initial phase, deactivated Deformation boundaries, Drained for Basement (LE) etc.
Thankyou Rushan Gizzatullin, it helped me a lot. God Bless You Sir !!
You are welcome =)