Structural forces in volume: Plaxis 3D

Question

Hi, 
 I am dealing with modelling of cross passage between two TBM tunnels. I have created the TBM tunnels by using tunnel designer and since my geometry requires lots of trimming and joining of surfaces and volumes I have detached the TBM elements from the tunnel designer. I have used volume element for the TBM tunnel lining and assigned properties of concrete. 
 Now my problem is I cant extract forces from the TBM lining. I have cut a section as well and tried to see the the forces and it is not happening. Can anybody guide me how to do that. 
 Thanks 
 Abhijith

Berk Demir · Answer

Your procedure is correct from bottom to top, but if your main concern is the structural forces, I wouldn't recommend using volume elements. Yes, Plaxis has a built-in structural forces calculation methodology for volume elements, but it will not work for complex geometries. So, I would recommend going back, creating the cross passage using plates. Be careful about connection of cross passage and TBM.

Stefanos Papavasileiou · Answer

Dear Abhijith, 
 The Structural forces in volume piles is not intended to be used in tunnel geometries as the one you describe. The complexity of the cross passage also does not qualify for using the dummy plate approach, so using plates might seem a good approximation. 
 Note that you could calculate the forces based on the stresses generated (integration), however, this is a cumbersome process that requires some post-processing work and it does require having some proper refinements to increase the accuracy of the results.

Structural forces in volume: Plaxis 3D

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