E' and c'/Su increase with depth (not level) in a Plaxis 3D model with varying ground surface (slope)

Question

Dear All, 
 I have a Plaxis 3D model in which the ground surface is a slope replicating the real topography (modelled using point cloud). Is there a way to assign E' and c'/Su increase with depth (not with level) in the Plaxis 3D model? Assigning E' and c'/Su increase with level for a slope generates unrealistic soil properties for soils in the bottom part of the slope if level (Zref) is choosen say at mid height slope. 
 Thank you. 
 Kind regards, 
 Victor

Dennis Waterman · Answer

Dear Victor, 
 There is no direct way to input E' and su increasing with depth, but for undrained shear strength it is possible to let PLAXIS determine the increase of shear modulus and undrained shear strength at the beginning of the calculation (so at the start of the first phase for instance) using the SHANSEP Mohr-Coulomb model. It will calculate the undrained shear strength based on the current stress state, and with a user-specified constant ratio of G/su the stiffness is calculated accordingly. 
 https://communities.bentley.com/products/geotech-analysis/w/plaxis-soilvision-wiki/46110/udsm---shansep-mc-model 
 With kind regards, 
 Dennis Waterman

Dennis Waterman · Answer

Dear James, 
 The SHANSEP concept can indeed be applied to many models - SHANSEP itself is not a model, but a way to deal with undrained shear strength. We have only implemented it for Mohr-Coulomb and NGI-ADP (User-Defined model DLL "ngiadps64.dll"). It would make little sense to apply SHANSEP to Hardening Soil or HSSmall, because those models pretty much reduce to the Mohr-Coulomb model if phi=0 is used. 
 With kind regards, 
 Dennis Waterman