With the release of PLAXIS 2D/3D CONNECT Edition V21, a new User Defined Soil Model is introduced: the PM4Silt model (Boulanger & Ziotopoulou, 2018).

PM4Silt is a stress-ratio controlled, critical state compatible, bounding surface plasticity constitutive model formulated recently by Boulanger and Ziotopoulou at the University of California, Davis. PM4Silt is suitable for simulating the response of low-plasticity silts and clays in geotechnical earthquake engineering applications. The model enhances the framework used for PM4Sand, a constitutive model for cyclic liquefaction of sands and non-plastic silts already available with PLAXIS 2D, to predict the features of undrained monotonic and cyclic loading responses, typical of those soils exhibiting stress history normalized mechanical behavior. It can reproduce the experimental evidence and empirical correlations of the undrained cyclic resistance across a wide range of initial shear and overburden stress conditions as well as the shear modulus decay and equivalent damping ratios.

Results from simulations of undrained cyclic DSS tests performed with two calibrations proposed for normally consolidated clayey silt and silty clay

With the release of PLAXIS 2D CONNECT Edition V21 (January 2021), this PLAXIS User Defined Soil Model is delivered with the PLAXIS installation. When using the 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.

With the release of PLAXIS CONNECT Edition V22.02 (October 2022) this PLAXIS User Defined Soil Model is updated.