New In 5.0


UDEC is faster and it has a new user-interface. The underlying calculation engine remains robust and reliable, but the user-experience is completely altered and enhanced.

To get an idea, the list of new or improved features provided below gives an overview (though it is not exhaustive; a complete list of changes to the program is available in the documentation supplied with the demo version).

New or Improved Features

Improved GUI

UDEC 5.0 has redesigned the graphical user interface (GUI) to be more functional, easier to use and includes all UDEC features available through the command line. Configuration switches have been added to enable the interface to provide comprehensive coverage but only show the features currently in use. This is intended to avoid overwhelming the new user but still support the more experienced UDEC users.

Screen shot of the new UDEC 5.0 GUI; click here to enlarge in a separate window

Several virtual models have been included in the GUI. The virtual models allow the modification of several base classes of geometries and then generating the UDEC commands to build them. Since the geometry is defined outside of UDEC, it is easier to modify the geometry graphically.

The ranges available to perform functions in the GUI have been expanded to include all of the UDEC command line ranges. This adds significant flexibility to model building.

A new FISH editor with parameters has been added to the GUI. This makes it easier to include FISH functions in GUI project files.

An HTML Help (chm) file provides the Command Reference and the FISH Users Guide from the UDEC Manual through the GUI.

Faster Calculations

Speed increases up to 30% faster than the previous version. Note that increases are subject to a wide range of variables (hardware configuration, model configuration, operating system, among others), thus speed increases are not uniform in all circumstances.

Speed increase on a P4 2.66GHz processor computer with Windows XP SP 2 running the "timing.dat" problem.

Improved Accuracy

UDEC 5.0 has more accurate plasticity solutions using Nodal Mixed Discretization. This technique averages the zone strains at common nodes which leads to a better plasticity solution by reducing the locking effect of lower order elements.

Added/Improved Structural Elements

UDEC 5.0 has added and improved its structural elements.

The structural liner commands have been improved by the adding of additional commands. These commands make it easier to add simple liners in tunnels and to more precisely control portioning of structural element nodes. The user can also import node placement in the form of tables.

New fixed degrees of freedom for structural nodes to allow lines of symmetry to be used with liners.

Color-scaled displacement vector field in a tunnel model using the improved structural liner. The Axial force on the liner is shown in blue.

A new rockbolt element has been added to UDEC. The new rockbolt element includes:

  • Bending and shear resistance.
  • Local stress dependant pullout strength based on the change in stress that has occurred since the bolt was installed.
  • The connection to the zone gridpoints in both the normal and shear directions is via coupling springs.
  • Softening as a function of shear displacement for the coupling spring can be prescribed using user defined strength tables.
  • The rockbolt may yield in both tension and compression.
  • Rockbolt rupture is based on a user defined tensile strain criteria.

Contours of displacement magnitude in a tunnel model. The axial forces on the rockbolt elements are also plotted.

New Fluid Flow Model

The fracture fluid flow logic in UDEC has been expanded to allow the modeling of gas flow. In Gas flow the bulk modulus of a gas is equal to its pressure.

Contour of gas pressure in joints surrounding a pressurized cavern.

Improved Automatic Voronoi Joint Generator

UDEC 5.0 has an improved automatic Voronoi joint generator.

A new algorithm has been implemented that reduces Voronoi block generation time by a factor of approximately 100. The Voronoi block generation range control has been modified to include any range command that can be used to select blocks. Previously only the JREGION RANGE was used.

Voronoi blocks generated to simulate a rock bolted beam of loose material.

In UDEC 4.0, there was a problem with finely discretized Voronoi block patterns showing a texture or preferred orientation. This “Texture” problem has been eliminated in the new version.

Voronoi blocks around a tunnel used to simulate spalling.

New/Extended Plotting Capabilities

UDEC 5.0 includes numerous new and extended plotting capabilities:

  • All vector quantity plots are now displayed with colors scaled to the vector magnitude. This makes determination of areas of high and low activity more apparent.
  • Joint normal and shear stress plots have been added.
  • Joint attribute plots are now displayed with colors scaled to the joint attribute magnitude.
  • New moment-thrust plot for structural liners.
  • New thrust-shear plot for structural liners.
  • New displacement magnitude contour plot.
  • New velocity magnitude contour plot.
  • Improved boundary condition plotting to include fluid settings.

Color scale vectors of displacement magnitude on a slope.

Enhanced Documentation

UDEC 5.0 includes significantly enhanced documentation. A major addition to the documentation is the compiled HTML Help. Explanations for all commands from the Command Reference and the FISH Users Guide are available online through the GUI.

Automatic Zone and Joint Model Loading

Zone and Joint DLL models are automatically loaded. The MODEL LOAD command no longer needed. This eliminates the inconvenience of having to reload models prior to restoring save files.

Hidden Construction Joints

UDEC 5.0 contains JOIN commands and keywords for welded construction joints. New keywords have been added to allow cracks to be specified as construction joints. These cracks are normally used to define excavation boundaries and to provide zone density control. This new feature allows them to be included while minimizing the effect on the model behavior.

Additional Features

FISH Functions

  • Reaction force FISH functions have been added to allow the retrieval of the boundary forces generated at fixed velocity boundaries.
  • FISH functions to retrieve the index strains EXX, EXY, and EYY have been added.

SOLVE Refinements

  • The SOLVE ELASTIC command has been modified to function the same as in our FLAC code. In SOLVE ELASTIC the model is given high strength properties and cycled until equilibrium is obtained. Then the original properties are restored and the model is again cycled to equilibrium.
  • The SOLVE FOS command now works for MHOEK (Modified Hoek Brown model) model (and any constitutive model that supports property scaling).
  • A new SOLVE RELAX command (similar to the FISH ZONK function) has been added. This function is used to slowly reduce boundary forces in excavations. The new command can also be used to automatically create a ground reaction curve.


  • You can now fix the centroid velocities of rigid blocks in specified directions. Previously it was only possible to fix the centroid velocities in all directions.
  • The ability to use a table to define the ground water surface has been added to the PFIX command.
  • SSI (maximum shear strain) and SSR (maximum shear strain rate) contour plots have been added to UDEC.
  • More precise history locator (grid point histories are now selected based on closeness with preference is given to zone that includes the coordinate). Previously the user was not able to control which gridpoint was selected for the history in the case where more than one gridpoint was at the same location in the model.
  • Added support to allow JMODELS and JOINT models to be used as the default constitutive models for newly formed contacts.
  • Using the command line interface: CALL, RESTORE, and SAVE without specifying a file name will open a windows file open dialog for visual file selection.