Pavement-Design Package

The pavement-design package (Potyondy, 2017) for the Particle Flow Code in 3 Dimensions (PFC3D) supports creation and triaxial testing of a synthetic unsaturated granular material containing geogrid.* The geogrid provides lateral restraint to the granular material as a result of interlocking and friction between the geogrid and the granular material, and this is believed to be the primary structural benefit of adding geogrid to the aggregate base layer of a pavement structure. The package can be used to study and quantify the effect of microstructural properties on macroscopic response, which includes the stress-strain curves produced during triaxial tests. The microstructural properties of the granular material include: grain size distribution of spherical or clumped grains, grain material type, moisture content and initial specimen porosity. The microstructural properties of the geogrid include: geometry, structural stiffness and grid-grain interface behavior. The package is being used to improve pavement-design methodology in Minnesota by estimating geogrid gain factors (defined as the ratio of resilient modulus of the aggregate base with geogrid to resilient modulus of the aggregate base without geogrid) for typical geogrid-reinforced aggregate roadway configurations in which the grain-size distribution, initial specimen porosity, moisture content and confining stress are varied (Potyondy et al., 2016; Siekmeier et al., 2016; Siekmeier and Casanova, 2016). The package could be extended to investigate the behavior of other aggregate-geogrid systems such as a geogrid pull-out or wheel-load test.

*  [The pavement-design package is provided in the form of a consistent set of FISH functions that operate within PFC3D version 5.0. FISH is a programming language embedded within PFC3D. The PFC3D code can be obtained from {}, and the pavement-design package is provided below --- you must be signed in to see the file.]


Potyondy, D. (2017) "Pavement-Design Package for PFC3D [pdPkg12]," Itasca Consulting Group, Inc., Technical Memorandum ICG16-8528-15TM (April 6, 2017), Minneapolis, Minnesota. DOWNLOAD LINK

The additional references cited above are defined in the references section of the pavement-design package memo, and the documents themselves are provided in the pdPkgN/Documentation directory.

Pavement-Design Package Software Update Revisions

pdPkg Release fistPkg Release PFC3D RELEASE Date / Description
12 25 5.00.30



  1. Create PFC3D beam contact model (see Potyondy [2017a] for model description and verification problem). The beam contact model matches the response (within 3%) of a tip-loaded cantilever beam subjected to axial, flexural and twisting deformations. The model is provided as a DLL that must be installed when installing the pdPkg.
  2. Enhance grid generation to provide biaxial and triaxial beamed grids in addition to existing biaxial parallel-bonded grids. The biaxial beamed grid has been calibrated to match SRT and ASM tests on Tensar SS20 geogrid. The triaxial beamed grid has been calibrated to match SRT and ASM tests on Tensar TX160 geogrid. The grids are symmetric --- i.e., there is no differentiation between TD and LD directions.
  3. Demonstrate that there are two offset curves of resilient modulus versus porosity for grid and no-grid models, with the grid curve lying above the no-grid curve. The effect of the grid on material stiffness is found by comparing the resilient moduli for the grid and no-grid cases at the same material porosity. This behavior is described at the end of the realistic pavement design example (see Figure 41).
  4. Use updated PFC3D executable (5.00.30) and fistPkg25.
  5. Clumped grains can be generated for both no-grid and grid models. For the no-grid case (in file MatGen.p3dvr), replace the call to mpParams-AG.p3dat, with a call to mpParams-AG_clumped.p3dat. For the grid case (in file MatGenGrid.p3dvr), replace the call to mpParams-AG_grid.p3dat, with a call to mpParams-AG_grid_clumped.p3dat.

Potyondy, D. (2017a) "Beam Contact Model [version 1]," Itasca Consulting Group, Inc., Minneapolis, MN, Technical Memorandum 2-3558-01:17TM07 (April 6, 2017).

Potyondy, D. (2017b) "Pavement-Design Package for PFC3D [pdPkg12]," Itasca Consulting Group, Inc., Minneapolis, MN, Technical Memorandum ICG16-8528-15TM (April 6, 2017).

11 24 5.00.27



  1. Pavement-Design Package [pdPkg10] made available to general public by posting to Itasca web page {} on Sep09_2016.
  2. Added citation of, and inclusion of, MnDOT pdPkg report {Siekmeier&Casanova(2016)-pdPkg.pdf}. Also add the technical summary of this report {MnDOT_TS(2016)-GeogridsIncrBaseStiff.pdf}.
  3. Fix bug that occurred when adding a grid to a cylindrical or spherical vessel. The bug caused the code to stop execution with an error message after generating the grains.
  4. Use updated PFC3D executable (5.00.27), and updated fistPkg (24).
10 23 5.00.24



  1. Use updated fistPkg (23).
  2. Rename master project directories to remove the "my" designators.
  3. Complete the realistic example in the pdPkg memo.

The first column of this table lists the Pavement-Design Package revision number; the second and third columns list the PFC 5.0 FISHTank and PFC3D 5.0 release, respectively, against which the Pavement-Design Package has been tested; and the fourth column describes the Pavement-Design Package revision. Note that each revision of the Pavement-Design Package is expected to operate with a PFC 5.0 FISHTank and PFC3D 5.0 release that is current or newer than that listed. Since newer revisions of the Pavement-Design Package may use features available only in newer revisions of the supporting software, they may not be compatible with older revisions of the supporting software.