how to input shear stiffness Ks and normal stiffness Kn to plaxis like we did in Flac ? and ignore Ri ?

Question

Stefanos Papavasileiou · Answer

Dear Ashraf, 
 Marco got me first! 
 With PLAXIS CONNECT Edition, you can adjust the Kn/Ks stiffness directly in the material data sets, in the Interface tab. 
 You need to switch the option in the Stiffness field, from Standard to Kn/Ks as seen below. The values for Kn and Ks can be provided independently in the data set.

Stefanos Papavasileiou · Answer

Dear Ashraf, 
 The Kn and Ks values only affect the stiffness used for the interface. The strength is still controlled by the Rinter as shown in the screenshot.

Stefanos Papavasileiou · Answer

Dear Ashraf, 
 I understand that in PLAXIS you can add Kn=Ks=1280Mpa which causes a soil body collapse error. 
 Typically, 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. 
 If you have a specific project for which you can identify the reason for the failure, please submit a service request so that we can assist you further: 
 https://apps.bentley.com/srmanager/ProductSupport