Overlapping zones and interfaces

Hi again,

I’m getting illegal geometry errors because my interfaces aren’t working as intended, and I don’t know why.

I’m basically modelling longwall panels, in a complex geology. The mesh was generated by Griddle, there are interfaces which represent geological faults and so on, but the problem doesn’t rely there.

General view of the model

Since I’m excavating longwall panels, I’m using Large-Strain mode on in this stage, the model seems converging after deleting some zones, however the interfaces I set on the roofs of the longwall panels aren’t detected and overlapping occurs, giving thus implausible displacements in the longwall panels (higher than their actual thickness or height). Here you can see the situation.

Overlap in the panels,

Panels totally excavated and adjacent zones get overlapped.

The code for interface creation looks more or less like this;

zone interface name ‘roofs’ create by-face separate new-side-group ‘Rocks_middle’ merge-nodes false range group ‘roofs’
zone interface name ‘roofs’ node prop stiffness-normal 4e10 stiffness-shear 2e10 friction 35
zone interface name ‘roofs’ tolerance-contact 1e-2
zone interface name ‘roofs’ node initialize-stresses.

The ‘Rock-middle’ group is the group in which the panels are excavated, I suppose that by doing this you impose the ‘master’ group, otherwise the interfaces get deleted as you excavate. Am I right about this?

The ‘roofs’ face group was generated from a geometry import from the exact surface mesh used in Griddle.

Now when I look at the interfaces I have in my model, only the ones of the geological faults are there, so it seems that the ‘zone relax excavate’ command is also deleting my roof interfaces.

What can I do to prevent interface deletion when excavating?

Thanks so much in advance, any ideas will be greatly appreciated.


Hi Felipe. I am might be incorrect here, but I believe that if interfaces are properly set up, they should not allow inter-penetration of zones even in the large strain mode. Would you be able to extract or set up a simpler model (maybe a subset of your model) in a way that you still see the same issue and send it to flac3dsupport@itascacg.com? With this general and rather complex description that you provided it is hard to give a more specific advise.

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