the bending moment of embedded pile and volume pile

Question

Hi everyone. I simulated pile with embedded beam and volume pile, respectively, as the methods mentioned in the paper ( T.P.T. Dao 2011). But, the bending moment of pile is significant different between embedded pile and volume pile under the same model parameters. The embedded pile and volume pile will need respectively the different soil parameters if the bending moment all is consistent with measured data. Why?

Stefanos Papavasileiou · Answer

Dear Wei, 
 I am not sure why you got a significant difference, but usually, publications involve many assumptions that are made by the authors. 
 Note that modelling a volume pile would require local refinements to be able to extract accurate stress results. 
 I would advise you to start with a simple model (axisymmetric for 2D, or quarter-symmetric for 3D), try to get good results and then calibrate the embedded beam elements to match those results. 
 Especially if you are working with PLAXIS 2D, one should not forget the Interface stiffness factors that are to describe the behaviour of the element with the surrounding soil. PLAXIS manuals explain these in detail and it is mentioned that valid for bored piles which are loaded statically in the axial direction and behaviour of the surrounding soil is modelled using the Hardening Soil model with small-strain stiffness. The phreatic level is assumed to be located at the ground surface. These values should be modified if the conditions in the model are different from the ones assumed to derive the default values. 
 If you need more assistance in setting up the model, please submit a service request: https://apps.bentley.com/srmanager/ProductSupport 
 If your question is on the publication, for that you may need to check the contact details of the authors.