New releases of PLAXIS CONNECT Edition V21.01

We are happy to announce that in April 2021 we released all-new PLAXIS versions: CONNECT Edition V21 Update 1. This includes PLAXIS 2D, PLAXIS 3D, PLAXIS 2D LE, PLAXIS 3D LE, PLAXIS Designer, and PLAXIS Monopile Designer.

CONNECT Edition V21 Update 1 adds functionality to improve productivity by improving the numerical process for non-linear systems using the new subspace accelerator, and we can use a new API to automate Limit Equilibrium slope stability analyses. On top of that, we made running analyses for offshore analysis of suction buckets easier using the new PLAXIS-SACS Suction Bucket Analysis tool.

By consolidating the product lines for geotechnical analysis since Version 21, we can now make big steps in interoperability between the Finite Element solution and the Limit Equilibrium solutions. The new consolidated PLAXIS product line also offers great new functionality with new constitutive soil models, e.g., NorSand, PM4Silt, and a new way to deal with unsaturated soil strength. We invested in improvements on tunnel CAD import. And we added a calculation convergence log to better understand the numerical process. Read below for more details.

Brand consolidation

To simplify our licensing and offer you more streamlined access to our newest, most advanced capabilities, we have consolidated our PLAXIS and SOILVISION offerings.

  • PLAXIS 2D, PLAXIS 3D and Dynamics, PlaxFlow, and Thermal modules have been repackaged into a tiered functionality system;
  • Prior offerings including SVSLOPE, SVFLUX, SVSOLID, and SVSOILS modules are consolidated into the PLAXIS LE offering.
  • Advanced tiers of these modules and SOILVISION Suites that include combinations of these modules are deprecated.
  • And former SOILVISION products have adopted the PLAXIS brand name and the LE suffix.

An overview of the new tiering system can be found here:

Do you want to upgrade to the latest version? See here for the process of upgrading.

PLAXIS Limit Equilibrium

Under the PLAXIS brand, Bentley now also offers Limit Equilibrium Method (LEM) solutions in addition to the well-known PLAXIS Finite Element calculations. PLAXIS LE is offered as PLAXIS 2D LE and PLAXIS 3D LE. This Limit Equilibrium software has a leading comprehensive set of functionalities for slope stability analysis: Predict design outcomes considering numerous soil models, support types, loading conditions, and design standards; Back-analyze efficiently using probabilistic methods and parameter sensitivity methods. Save time and resources with automation tools for modeling geographically larger areas, multiple analysis types, and common design scenarios. In combination with PLAXIS Designer as its conceptual model builder counterpart, you can quickly generate complex 3D models ready for the numerical analyses that PLAXIS LE has to offer.

Combining PLAXIS 2D LE and PLAXIS 2D

When using a PLAXIS 2D Limit Equilibrium model, it is now easier to continue your analysis directly in PLAXIS 2D to run a Finite Element calculation: we can directly launch the same model in PLAXIS 2D, considering the geometry, soil materials, and structural elements:

More info is available here: Importing PLAXIS LE into PLAXIS 2D.

New Soil behavior models in PLAXIS 2D and PLAXIS 3D


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.

NorSand: Undrained mechanical response predicted by NS for loose and dense conditions

Figure: Undrained mechanical response predicted by NS for loose and dense conditions

More details and documentation: NorSand


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.

PM4Silt - PLAXIS UDSM results in CDDS test

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

More details and documentation: PM4Silt

Fluid model

This constitutive model has been specifically created to simulate the effects of free water on water-retaining structures and quay walls or any other situation involving fluid-structure interaction. Like any other material model in PLAXIS, the fluid is simply modeled as a solid continuum, with the capability to support an indefinite level of hydrostatic pressure and, more importantly, to exhibit negligible shear stresses. The only specific parameter to be defined is the bulk modulus of the fluid (e.g., K = 2.2GPa in case of water) whereas the shear modulus is internally calculated to avoid numerical issues due to the incompressibility constraint, that is Poisson’s ratio approaching 0.5. This model comes in handy when hydrodynamics pressure build-ups need to be taken into serious consideration in the design, specifically when more simplified and straightforward procedures based on the added mass concept, also available in PLAXIS, prove to be not suitable or sufficiently accurate for the purpose.

Fluid model

Figure: Dynamic displacement response of a dam comparing the Fluid model against the added mass feature

More details and documentation: Fluid model

Importing tunnel geometry CAD data in PLAXIS Tunnel Designer

Importing tunnel cross-sections from CAD files is now easier and more robust.

Better calculation convergence

Subspace acceleration

A new numerical control parameter was added to the PLAXIS 2D and PLAXIS 3D calculation settings. This newly added Subspace accelerator in the phase settings helps to improve the behaviour of slow converging calculations, especially when dealing with large non-linear systems.

As the PLAXIS Monopile Designer 3D calculation showed huge performance improvements using this new numerical control parameter, this is now activated by default when running a 3D Finite Element calculation from the PLAXIS Monopile Designer.

Calibration benchmarks for PLAXIS Monopile Designer, showing the combined effect of subspace acceleration and calibration with target displacement (see below). Calculation time may vary depending on hardware settings

Figure: Calibration benchmarks for PLAXIS Monopile Designer, showing the combined effect of subspace acceleration and calibration with target displacement (see below). Calculation time may vary depending on hardware settings

A better understanding of the FE convergence process

If a calculation does not run as smoothly as you expected, or it appears that the phase calculation does not convergence, it was sometimes a bit difficult to understand why this is the case. Since this release, inspecting these details is now a lot easier using the Calculation Log Collector! You can inspect any phase by just selecting the option from the Phases Explorer or Phases Window (left), or access it while the phase is still calculating launch it directly from the Calculation Progress Screen (right):

Access to convesion log in Phases Explorer and Calculation Progress window

Figure. Access to conversion log in Phases Explorer (left) and during calculation in the progress window (right)

For more details, please read Calculation Kernel Convergence log

PLAXIS-SACS Suction Bucket Analysis tool

PLAXIS - SACS Suction Bucket Analysis

Released as Technology Preview: a new tool to enhance the analysis of offshore foundations: a new tool designed for suction bucket analysis that combines the great features of PLAXIS 3D and SACS.
Full instructions are available here: PLAXIS-SACS Suction Bucket Analysis Manual.

Calibration with target displacement at mudline in PLAXIS Monopile Designer

In previous versions, it was only possible to impose a prescribed displacement at the top of the pile, which required guessing before calculating how that would translate into the desired displacement at the mudline. This led to calculations either taking longer than needed or some trial-and-error to find the right value of the prescribed displacement. This parameter has been replaced by a target displacement at mudline, relative to the diameter of the monopile. PLAXIS Monopile Designer will automatically estimate the prescribed displacement imposed at the top and automatically stop the analysis when the calculation reaches the target point. This makes the Calibration process much more efficient and predictable. When further combined with the Subspace accelerator, now active by default, it can lead to significant speed improvement.

Calibration with previous version (left) and V21 (right) for a target displacement = 1 m

Figure: Calibration with previous version (left) and V21 (right) for a target displacement = 1 m

Defining shear strength above the water table with complex geology in PLAXIS LE

The option to define an alternate material shear strength in the unsaturated zone above the water table, without having to adjust your complex model geometry, offers you a significant reduction in model setup time with this release of PLAXIS LE - Slope Stability Analysis. The site geology at open pit mining operations, surrounding large earth dams, and along extensive infrastructure corridors is often complex and requires the definition of numerous material zones in your model geometry. Different material shear strength constitutive models may be appropriate to represent the behavior below and above the water table to represent undrained or drained conditions. When considering the water table a 2D model with 40 zones could require an additional 40 zones to be entered and a material assigned. This challenge becomes greater when defining full 3D models and then multiplies when changing water level scenarios are needed! Take advantage of the Above Water Table Use Strength option when defining a material to reference an alternate material definition and remove the need to define extra model geometry!

Complex 2D and 3D models requiring alternate shear strength above the water table

Figure: Complex 2D and 3D models requiring alternate shear strength above the water table

Automation of Limit Equilibrium models

With the release of PLAXIS 2D/3D LE V21.01, you are now also able to automate the creation of your Limit Equilibrium models using PLAXIS LE’s API technical preview.

PLAXIS LE API/Python example

User-Defined Unsaturated Shear Strength for Limit Equilibrium models

Engineers are encountering local material behavior that does not always fit with the pre-defined unsaturated shear strength definitions. With the release of PLAXIS 2D/3D LE V21.01, you can now directly enter custom unsaturated shear strength relationships to improve your analyses.

a new PLAXIS LE soil model: Unsaturated User Defined

Figure: a new PLAXIS LE soil model: Unsaturated User Defined

So, update to our latest editions to benefit from these new features and software improvements using either the CONNECTION Client or download the software yourself today!

Full release notes with all added features:

PLAXIS 2D CONNECT Edition V21 Update 1 PLAXIS 3D CONNECT Edition V21 Update 1 PLAXIS MoDeTo CONNECT Edition V21 Update 1 PLAXIS Output Viewer CONNECT Edition V21 Update 1 PLAXIS Designer CONNECT Edition V21 Update 1 PLAXIS 2D/3D LE CONNECT Edition V21 Update 1


CE V21 Update 1

April 2021


CE V21 Update 1

April 2021

Monopile Designer
CE V21 Update 1

April 2021

Output Viewer
CE V21 Update 1

April 2021

PLAXIS Designer

CE V21 Update 1

April 2021


CE V21 Update 1

April 2021