UDSM - UBCSAND3D Model

Created:May 2, 2011
Last updated:June 12, 2013
Application:

The Plaxis Liquefaction Model is a full 3D implementation of the UBCSAND model by P. Byrne et.al.
This model is available as a user-defined soil model Dynamic Link Library (DLL).
The DLL can be obtained from and is supported by Plaxis.
However, Plaxis does not accept any responsibility when using this DLL.
Hence, the user needs to validate results obtained from this model by him/herself.

In order to obtain the model, please contact our sales department.

Support on the use of the UBCSAND model is only provided for this DLL under the conditions of the PLAXIS VIP support service and Article 10 of the End-User Licence Agreement.

Model history


Update June 2013 - version 2013.150.150.0
Based on recent user feedback we improved the robustness of the model significantly.
The model description and formulation is not changed, neither the behavior of the model in a stress point (Plaxis SoilTest facility) where the strain increments are relatively small. However, the improved performance and behavior of the model can be seen in numerical models run with PLAXIS like the finite element validation example in the report (Dynamic Centrifuge, Chapter 2.3).

Note that the model is still under development and validation and a final release will be available as soon as this process comes to a final stage.

Update January 2013
A new updated version of the UBC3D-PLM model (UBCSAND 3D) implemented as a User Defined Model for Plaxis 2D and 3D. The updated formulation is in accordance with the 904aR version of the 2D UBCSAND as published recently by Beaty and Byrne (2012).
Moreover, the robustness of the model is significantly improved and more accurate results are achieved in boundary value problems. The speed of calculation in several cases where the new model is tested is dramatically improved.

The new model includes:

  • An updated densification rule which is valid for stress paths which do not start from the isotropic axis. Higher accuracy achieved when anisotropic consolidation is considered.
  • An updated rule for modelling the post-liquefaction behaviour in loose sands and the cyclic mobility in dense sands.
  • An improved formulation which gives higher accuracy in boundary value problems and significantly improves the speed of calculation.

Note that the model is still under development and validation and a final release will be available as soon as this process comes to a final stage.

Update June 2012
Plaxis improved the PLAXIS UBCSAND-3D soil model to give higher accuracy in cyclic loading. More specifically, the new update predicts more accurately the evolution of the excess pore pressures with the use of a soil densification rule for cyclic loading and two yield surfaces for primary and secondary loading respectively. Moreover, the post liquefaction behaviour can be approximated after an extensive calibration of the input parameters with the proper element tests.
Plaxis is working on a full 3D implementation of the latest UBCSAND formulation (904aR; Beaty & Byrne, 2011). This version is expected to be released end 2012 / early 2013.

Update November 2011
Plaxis has extended the original UBCSAND model into a full 3D formulation and has made this available as a user-defined soil model (UDSM) to our users under the conditions of the PLAXIS VIP support. It is known that the version of the PLAXIS UBCSAND-3D model (October 2011) exaggerates the development of excess pore pressure upon cyclic loading, which leads to earlier liquefaction than what is observed for sands in reality. This will at least result in a conservative conclusion with respect to stability.

Downloads

UBC3D-PLM (REPORT).June2013.pdf Plaxis Liquefaction Model UBC3D-PLM, June 2013 pdf| 2.13 MB
Development of a Liquefaction Model.pdf Plaxis Liquefaction Model UBC3D-PLM Feb 2010 pdf| 2.3 MB
UBC3D-PLM (REPORT).May2012.pdf Plaxis Liquefaction Model UBC3D-PLM Report May 2012 pdf| 5.22 MB
UBC3D-PLM (REPORT).Jan2013.pdf Plaxis Liquefaction Model UBC3D-PLM Report January 2013 pdf| 2.24 MB
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