The pavement-design package (Potyondy, 2019) 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 HERE, and the pavement-design package is provided below.
References
Potyondy, D. (2019) "Pavement-Design Package for PFC3D[pdPkg15]," Itasca Consulting Group, Inc., Technical Memorandum ICG16-8528-15TM (April 1, 2019), 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.
Complete final pdPkg for PFC3Dversion 5. This package will be ported to operate with PFC3Dversion
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.
14
25
5.00.35
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.
13
25
5.00.32
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.
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]
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.
Add capability to perform resilient-modulus tests, and to perform DCP and LWD probes to ExampleProjects\MG-HillGrid.
Provide additional Documentation items (see pdPkg-Documentation.pdf in Documentation directory).
12
25
5.00.30
4/10/2017
MODIFICATIONS
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.
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.
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).
Use updated PFC3D executable (5.00.30) and fistPkg25.
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. (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
10/17/2016
MODIFICATIONS
Pavement-Design Package [pdPkg10] made available to general
public by posting to Itasca web page
{www.itascacg.com/pavement-design-package} on Sep09_2016.
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}.
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.
Use updated PFC3D executable (5.00.27), and updated fistPkg (24).
10
23
5.00.24
06/23/2016
MODIFICATIONS
Use updated fistPkg (23).
Rename master project directories to remove the "my" designators.
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 PFC5.0 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.
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