# Trying to understand tunnel convergence differences

Hello, we are trying to understand ground behavior in a tunnel excavation. We have run two models, the only difference is that the first one has soft soil from excavation axe to the surface, below axe is rock mass; the second one everything is soft rock. There is a face and lateral pressure applying on excavation surface. Unexpected, we get more convergences and totally different contour in the model with rock mass. Attached you can find outputs from FLAC3D.

Could you help us with the interpretation of this? I can send you the codes if required.
Thank you.

Hi Carlos, without looking at your code, i suggest to you check 2 things:

1. Check the density you are using in the material called â€śFha-Rellenos_cohesivosâ€ť
2. Run the model without the material called â€śFha-Rellenos_cohesivosâ€ť

tell me what results from it,

Regards

IÂ´ve changed material from â€śFha-Rellenos_cohesivosâ€ť to â€śQmk-Lama_del_Pacificoâ€ť but I still have the same problem.

Wow, that is interestingâ€¦ what if you take out the forces? just to understand the â€śpureâ€ť response of soil and rock?

and what if you change OV-2-suelo_residual for QMK - lama del pacifico?

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If forces are taken out, high deformation occurs and calculation stops (large strain on). Here are the codes I am using, they are the same except for ground assignment.
Effective_all_materials.dat (8.9 KB)
Effective_only_Lama.dat (6.4 KB)

Many thanks.

Changing OV-2-suelo_residual for QMK - lama del pacifico, we get same results, there are much more convergences in tunnel crown when part of the model is rock mass as seen in next plots.

Thank you.

Carlos, i can see less convergence in these new plotsâ€¦ you are having -1.69e-2 maximum displacement (vertical), while in the first ones you got 2.8e-1 (total)â€¦ can you unify the color scale?

also, i were looking at your code, and i saw that when you apply multiple materials, you also apply different stress field wich has a direct influence in the deformation process

Thanks Matias. Sorry for changing plots to Z disp, here you can see plots with the same color scale in total displacements.

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