Aggregate base residual stresses affecting geogrid reinforced flexible pavement response

This paper presents findings of an analytical study aimed at investigating the effects of unbound aggregate base residual stresses on the resilient response behaviour of geogrid reinforced flexible pavements. A finite element (FE) based mechanistic response model recently developed at the University of Illinois was used to predict critical pavement responses of unreinforced and geogrid reinforced flexible pavements. The nonlinear analyses performed in the base and subgrade also considered different horizontal compressive residual stress distributions introduced as locked-in initial stresses in the base course due to pavement construction and subsequent repeated traffic loading. The primary focus was to study effects of increased confinement and stiffening around geogrid on improved granular layer moduli and reduced critical subgrade vertical strains/stresses by assigning initial residual stresses around the geogrid tensile reinforcement in the FE pavement continuum analysis. An increase in horizontal confinement resulted in significant increases in the moduli of the base and subgrade layers in the vicinity of the geogrid reinforcement. The degree of structural benefit provided by geogrid reinforcement could be successfully quantified in the response analysis to show the commonly observed technical benefit of geogrids in the field.