PLAXIS3D - Laterally Loaded Pile Bearing Capacity

Question

Hi! 
 I am trying to find the lateral bearing capacity of a pile. It is modelled as a volume element, being laterally displaced by 0.2m. 
 Given soil parameters of strength (s_u) 25 kPa, pile length (L) 2.5m and diameter (d) 0.1m - theoretically arrive at value using 9x's_u'x(Ld) = 56.25 kPa, however, PLAXIS simulation results in ultimate load of over double at 124 kPa. 
 Is there any potential reasons for this? 
 Many thanks, 
 Ben 
 Note: model setup using plates and interfaces.

Stefanos Papavasileiou · Answer

Dear Ben, 
 Results from finite element analyses may sometimes differ from theoretical solutions as these usually have very strict assumptions, e.g. linear behaviour or uniform material, drained behaviour, etc.. 
 I would suggest you check what are the assumptions on the theoretical solution and try to replicate the same conditions in PLAXIS, too. In general volume elements give very good prediction when there is adequate number of elements, which you may need to improve in your case. 
 If you still have questions on this, please please submit a service request. Then, one of our support engineers can help you in detail: https://apps.bentley.com/srmanager/ProductSupport