The hypoplastic sand material model developed by Wolffersdorff (1996) and implemented by David Mašín at Charles University in Prague captures the pressure- and density-dependent response of both loose and dense sand for a wide range of stress conditions.
The Add-In and its documentation are available for download from the soilmodels.com web site.
Note: This Add-In can only be used with GeoStudio 2020 and earlier.
SIGMA/W