Initial stress condition using subroutine SIGINI

[Roiso]

Hello to everybody, I'm new in the forum and with abaqus ,

I'm trying to model a soil sample on axisymmetric (60m depth, 20m width).
I'm using SIGNINI to introduce an initial stress state (S11 and S33), I read that after applying initial conditions I have to apply a GEOSTATIC step and apply gravity (so abaqus will find equilibrium for the stresses imposed with my subroutine).

-If the constitutive law for soil is elastic the model works. But if I used a Mohr-Coulomb criterium it doesn't converge. Do you know what can I do, I need to use a non linear constitutive law.
-I also try applying a STATIC step where I apply gravity after initial conditions and stress changes and it only converge using Static, risk step.

Thanks a lot for your help
Regards Rocio