Hello Itascan! I got strange displacements at a fix boundary. First, the model reaches equilibrium with Mohr-Coulomb model allowing vertical displacement at boundaries then, initialize all disp to zero and gp displacements are fix at boundaries; then start a tunnel excavation. During excavation displacements at boundary are increasing until this final situation.
This is a partial excavation image:
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Dear Carlos_Mora. This analysis is considered a shield analysis under tunnel face pressure. Therefore, in the case of boundary displacement, the pressure should only act on the tunnel surface, but since it also acts on the boundary surface, it appears that a strange boundary displacement occurred. Therefore, I think the problem can be solved by using the “zone face apply-remove” command or by adjusting the range where the pressure is applied.
Thanks Cheng and Galleon. Yes, I was using the “zone face apply-remove” command. I created a new mesh and solved the problem. I did not have time to look for the problem.