How to assign boundary conditions for earth model? 1

[roudan]

Hi

I am modelling earth deformation due to underground pressure and temperature change. There are in-situ horizontal stress and vertical stress in earth. I am wondering which way to assign boundary conditions during modelling. In the below figures, I list two approaches, the first approach uses geostatic stress equilibrium first to create initial vertical and horizontal stress distribution first then add boundary displacement constraint, for this approach, I keep model big enough to assume no horizontal displacement in far away boundary. The 2nd approach just apply horizontal stress to one boundary to mimic original horizontal stress, then keep this boundary loading the same in steps. Which one is more correct? I always use the first one which I learnt from the school. But recently I did see someone uses 2nd approach. So I like to hear your opinion. Thanks

 

[FEA way]

Did you try using both approaches for the same model to see whether the results will be identical or not ? Personally, I think that I would stay with the first method.

 

[roudan]

Thanks FEA way. I have not tried both ways. Would you mind sharing your opinion what is the problem with 2nd approach? Thanks

 

[FEA way]

The first approach gives more control over the applied stress state in the model since both components are specified directly.

 

[roudan]

Thanks FEA Way. That make senses! I appreciate your help.