Software Products

04/08/19

Complete final pdPkg for PFC3D version 5. This package will be ported to operate with PFC3D version 6. Add magazine article (Siekmeier&Bittmann(2019)-MN_UseOfGrid.pdf) to Documentation directory. This article describes the work that has been recognized by the University of Minnesota Center for Transportation Studies 2018 Research Partnership Award to Geogrid Reinforced Aggregate Base Pavement Design.

Add report (Siekmeier(2018)-GeogridAggBase.pdf) to Documentation directory. This report utilizes the pavement-design package to provide a performance specification consisting of DCP and LWD target values for geogrid reinforced aggregate base.

6/22/2018

Provide report (PFC_PavementDesign-Phase2.pdf) and associated documents in Documentation directory. This report summarizes the work for the MnDOT project "Geogrid Specification for Aggregate Base Reinforcement." The pdPkg14 is the deliverable of the project.

3/10/2018

The package has been provided to John Siekmeier of MnDOT as a deliverable for the project "Geogrid Specification for Aggregate Base Reinforcement." The work is summarized as follows, with documentation listed in square brackets after each item --- see REFERENCES section below for abbreviations.

1. Extend the geogrid representation to allow different geogrid types to be modeled. Create beam contact model, and verify that a string of spherical balls joined by beamed contacts provides the behavior of a structural beam of rectangular cross section with properties of Young's modulus and Poisson's ratio. Enhance geogrid representation via beamed grids, add ability to create triaxial beamed grids, and determine grid properties to match Tensar SS20 Single Rib Tensile (SRT) and Aperture Stability Modulus (ASM) grid tests. [pdPkg & BCM]
2. Add Multiple Aperture Tensile (MAT) grid test. [pdPkg]
3. Enhance hill material to include general grain shapes via clumped grains. [fistPkg, example of use in MV]
4. Add typical roadway model, used to map out the modulus-porosity-grid-grain shape relationship. [MV]
5. Add Dynamic Cone Penetrometer (DCP) and Light Weight Deflectometer (LWD) probes. [MV]
6. Did not investigate ideas to improve material genesis. Did not investigate behavior during large-strain triaxial tests; however, PFC3D modeling of railway ballast by Mahmud (2017) suggests that matching the triaxial shear strength (maximum deviator stress that can be sustained by the material) requires polyhedral grains, because clumps are not sufficiently angular. It is not yet known if resilient modulus can be matched by clumps or polyhedral grains.

REFERENCE

Mahmud, S.M.N. (2017) "Effect of Particle Size Distribution and Packing Characteristics on Railroad Ballast Shear Strength: A Numerical Study Using the Discrete Element Method," M.S. Thesis, Boise State University [advisor: Deb Mishra].

REFERENCES (in Documentation directory)

[fistPkg] Potyondy, D. (2017) “Material-Modeling Support in PFC [fistPkg25],” Itasca Consulting Group, Inc., Technical Memorandum ICG7766-L (March 16, 2017), Minneapolis, MN.

[pdPkg] Potyondy, D. (2018) “Pavement-Design Package for PFC3D [pdPkg13],” Itasca Consulting Group, Inc., Technical Memorandum ICG16-8528-15TM (March 9, 2018), Minneapolis, MN.

[BCM] Potyondy, D. (2018) “Beam Contact Model [version 1],” Itasca Consulting Group, Inc., Technical Memorandum 2-3558-01:17TM07 (March 9, 2018), Minneapolis, MN.

[MV] Potyondy, D. (2018a) "Model-Validation Tests," Itasca Consulting Group, Inc., Technical Memorandum 2-3558-01:17TM52 (March 9, 2018), Minneapolis, MN.

MODIFICATIONS

1. Add memo ModelValidationTests.
2. Add typical roadway model (see ModelValidationTests).
3. Fix minor typoes in pdPkgMemo.
4. Move grid tests to ExampleProjects\GridTests.
5. Add Multiple Aperture Tensile (MAT) test to \GridTests.
6. Rename grid-set parameters (grid-grain => grid-surface):
   • gd_ggemod => gd_gsemod
   • gd_ggkrat => gd_gskrat
   • gd_ggfric => gd_gsfric
7. Add capability to perform resilient-modulus tests, and to perform DCP and LWD probes to ExampleProjects\MG-HillGrid.
8. Provide additional Documentation items (see pdPkg-Documentation.pdf in Documentation directory).

4/10/2017

MODIFICATIONS

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.

REFERENCES
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).

10/17/2016

MODIFICATIONS

1. Pavement-Design Package [pdPkg10] made available to general public by posting to Itasca web page {www.itascacg.com/pavement-design-package} 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).

06/23/2016

MODIFICATIONS

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