How to model the foundation of the structure with Plaxis 3d (v2013) software?

Question

I have a simulation performed by plaxis 2013 , which collapses and it does not converge properly. I would appreciate it if someone could give me an idea of the problem.
This is a model of the wind turbine foundation where I’ve used the Mohr-Coloumb constitutive model for modeling the soil around the foundation, and the plate element technique (and their extrude) for the modeling of the foundation.
The modeling has three steps:
1- The first step: calculating the initial stresses
2- The second step: defining and modeling the foundation of the structure
3- The third step: applying the load
During the analysis of the model, at the step of applying load on the foundation, the soil around the foundation uplifts and foundation deformation is positive while it seems the problem does not relate to the load value. I have also tried to add a negative interface between the bottom of foundation and the soil which did not impact the result.
I am looking forward to hearing any idea on the probable problem on my modeling procedure and/or boundary conditions,
Thanks in advance

Stefanos Papavasileiou · Answer

Dear Hamidreza, 
 We no longer support PLAXIS 3D 2013 as we have released 6 newer versions with lots of improvements and new features. Our currently supported versions are PLAXIS 3D CONNECT Edition V20 (Update 2) and PLAXIS 3D 2018 version. 
 In general, in order to find out what the mechanism for failure is, and so possibly determining the cause, these Output plots should be inspected: 
 
 deformed mesh 
 total displacements (shaded plot) 
 incremental displacement (shaded plot and/or arrows) 
 total deviatoric strain (shaded plot) 
 incremental shear strains (shaded plot) 
 Plastic Points plot 
 when applicable: excess pore pressure plot 
 
 A combination of these plots will usually give insight into what is happening. 
 Note that a big role is also played by the constitutive model used. The Mohr-Coulomb is a linear elastic perfectly plastic model with a Mohr-Coulomb failure criterion, which can explain the reason for the unrealistic uplift you see in the results. 
 Please consider upgrading your version so that we can assist you further with your project. To request for an upgrade, please submit a Service Request following the link here: https://apps.bentley.com/srmanager/

Stefanos Papavasileiou · Answer

Dear Hamidreza, 
 The question is whether it is important to you and the project to simulate the interaction between the different pieces. If the pieces are fully connected then an interface is not needed. If the pieces can move relative to each other then an interface can be used. 
 Typically for soil to structure interaction, the interface is required so that it is possible to have a relative movement of the soil. Without an interface, the nodes of the soil will be fully connected to the nodes of the structure. 
 In both cases, this depends on the engineering and design decisions.

How to model the foundation of the structure with Plaxis 3d (v2013) software?

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