Abstract:
The behavior of a jointed plain concrete pavement (JPCP) has been investigated under
single wheel load for interior loading using finite element technique to predict the
critical pavement responses for nonlinear geomaterial characterization. Pavement
foundation geomaterials, i.e., fine grained subgrade soils and unbound aggregates
used in untreated base/subbase layers, exhibit nonlinear behavior. The idealized
pavement system is analyzed using both 3D and axisymmetric (2D) finite element
analysis. The developed 3D and axisymmetric models were analyzed for four
combinations of material characterizations- (1) linear base and subgrade material, (2)
nonlinear base and linear subgrade, (3) linear base and nonlinear subgrade, and (4)
nonlinear base and nonlinear subgrade. Effects of slab thickness, base course material
thickness, base course material strength, and subgrade type on the critical pavement
responses were also studied.
For the finite element analysis an axisymmetric and 3-D finite element model of
jointed plain concrete pavement was developed using the general purpose finite
element software ABAQUS. Granular base course and subgrade soil was modeled
with solid elements considering its nonlinear material behaviors, and concrete slab
was modeled with linear elastic material using solid elements. Eight nodded
isoparametric brick element was used for 3D modeling and 4 noded linear
quadrilateral element was used in axisymmetric modeling. The developed 3D FE
model was successfully verified with available numerical results.
3D finite element analysis results for nonlinear material characterization predicts
12.4% higher surface deflection than linear elastic characterization. But the maximum
tensile stress and vertical compressive stress on top of subgrade for both nonlinear
and linear analysis were found to be negligible. 2D axisymmetric FE analysis was
carried out and the results were compared with those predicted by 3D FE analysis.
The axisymmetric finite element analysis results conforms closely with the 3D FE
analysis results for vertical surface deflection and compressive stress on subgrade
with a variation of 1.3% and 2.4% respectively. But the maximum tensile stress
predicted by axisymmetric FE analysis at the bottom of the concrete slab is about 14%
grater than the 3D FE analysis result. Nonlinear characterization of the base course
material has no significant effect on the pavement responses as the stresses developed
in the base course material layer is within the elastic limit. Nonlinear characterization
of subgrade soil has considerable effect on the deflection of the top surface. The
parametric study shows that for a jointed plain concrete pavement, the maximum
values of pavement deflection, tensile stress and subgrade pressure are reduced
significantly up to a thickness of 225 mm (9 inch) above which the influence of slab
thickness on pavement responses reduces. The effects of base course material
thickness and strength properties on the maximum values of pavement deflection, tensile stress and subgrade pressure are less significant compared to effects of slab
thickness. The subgrade type has similar but significant effects on the pavement
responses due to wheel load.
