With the release of PLAXIS 2D/3D CONNECT Edition V21, a new User Defined Soil Model for (static) liquefaction analysis is introduced, the NorSand model (Jeffries, Been, 2016).
NorSand (NS) is a critical state soil model implemented within the wider theory of work-hardening plasticity. It is capable to account for the effect of void ratio on soil behavior by using the state parameter as a key controlling variable, that is the difference between the void ratio and its critical state value. The "Sand" in the model is only to denote the ability of NS to accurately represent the dilation of dense soils. Soil properties in NS are limited in number, mostly standard in the geotechnical community, and can be easily obtained via conventional laboratory tests. Usually, a few triaxial compression tests will suffice to calibrate the model. Although the most prominent use of this model has been to simulate static liquefaction of loose silts, it can be used to capture soil behavior over a wide range of densities and confining stresses.
Figure: Undrained mechanical response predicted by NorSand for loose and dense conditions
Hint: Strength in the NorSand model is not reduced in a Safety analysis.
Coffee Corner: Geotechnical Analysis - NorSand: Liquefaction analysis in PLAXIS [Webinar, Sept 2021]
Bentley Webinar: PLAXIS introduces NorSand model with creator, Mike Jefferies [Webinar, March 2021]
Validation of computational liquefaction for tailings: Tar Island slump [Publication]
How to use a user defined soil model in PLAXIS [Videos]
Plaxis User Defined Soil Models [Models]
With the release of PLAXIS 2D/3D CONNECT Edition V21 (January 2021), this PLAXIS User Defined Soil Model is delivered with the PLAXIS installation. When using the PLAXIS Advanced or PLAXIS Ultimate version and enabling the Geotechnical SELECT Entitlement [GSE] when starting the PLAXIS application, this model becomes available in the Parameters tab when selecting "User-defined" for the Material model.