structural analysis of a Tunnel with Karamba?

Hello,

I'm trying to do a structural analysis of a tunnel (just a section (in the moment)).

(Later, if possible, I will try a 3d model too.)

I started allready based on Images of tunnel FEM analysis.

(Images and definition attached (load and material is not set correctly yet))

But I'm still not really sure if it is even possible with Karamba?

If not is it even possible to do a structural analysis of a tunnel using Grasshopper?

Does someone did already something similar?

According to the process I have some other questions:

1. Is it somehow possible to set a lineload on a shellelement?

2. How do I set the supports correctly for a tunnel?

Best,

Martin.

Attachments:

tunnel - structural analysis - test 01.jpg, 1.1 MB
tunnel - structural analysis - test 01.gh, 31 KB
tunnel - structural analysis - test 01.3dm, 558 KB

Replies to This Discussion

Permalink Reply by Karamba3D on August 11, 2013 at 5:06am

Hello Martin,

whether or not Karamba is the right tool for modeling a tunnel depends on what aspects of the problem you want to simulate. For e.g. analyzing the earth pressure on the tunnel lining non-linear FEA needs to be applied because of the non-linear material behavior of soil.

Karamba shells are plane stress elements. In order to use them for a plane strain problem like yours the material parameters need to be adapted: E* = E/(1+nue); nue* = nue/(1-nue) where G*=E*/(2*(1+nue*)). E* and G* are fictitious Young's Modulus and shear modulus for a material in a plane strain setting.

There is no Line-Load on shell component in Karamba 1.0.3. The closest thing to that would be a mesh-load on a slender rectangle.

You could use symmetry to half the size of the model. I would set the support conditions such that there are no horizontal movements on the lower, left and right boundary. The lower boundary needs to be also vertically supported.

Best,

Clemens

Permalink Reply by Martin Dembski on August 11, 2013 at 8:40am

Hello Clemens,

thank you for the hints.I will try them.

Best,

Martin.

Permalink Reply by Martin Dembski on August 21, 2013 at 7:32am

Hello Clemens,

I searched now a while to find values for the materials.I also got some, but what did you mean with "nue" in your equations above, because I couldn't find anything about it?Best,

Martin

Permalink Reply by Martin Dembski on August 26, 2013 at 9:36am

Got it, nue is the Poisson-value.

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