In Situ Testing Informed Sublayering Approach for Mechanistic Analysis and Design of Geogrid-Stabilized Pavement Foundations

Abstract

This study introduces a sublayer-based modeling approach to characterize the stress-dependent modulus behavior of pavement unbound aggregate layers stabilized using geogrids. Current modeling and design approaches either apply a higher uniform layer modulus or disregard geogrid stabilization benefits. A uniform increase in modulus in the depth profile, however, does not capture the localized stiffening caused by an installed geogrid, also referred to as the mechanically stabilized layer (MSL). Using instrumentation and testing during an actual highway reconstruction project in Indiana, the MSL concept was modeled by discretizing the aggregate base into sublayers. Automated Plate Load Tests (APLTs) conducted during construction of the aggregate base test sections provided field data to characterize the modulus behavior for each sublayer using a nonlinear stress-dependent resilient modulus model. The calibrated model parameters for each sublayer were then implemented in a finite element solution for the field experiment to predict the APLT-measured deflection basins. Once validated, the sublayer model was used to estimate and report on the subgrade vertical stresses and strains. The results revealed that geogrid-stabilized sections exhibited lower subgrade stresses and strains compared with the no-geogrid control section. Therefore, this study demonstrated the implementation of a new sublayer-based parameterization technique that captures stiffness gradients and geogrid stabilization effects. The methodology provides a mechanistic and field-calibrated pathway for incorporating geogrid stabilization into mechanistic-empirical (ME) pavement design. A broader adoption of testing and field sensor data-informed ME frameworks linked to digital twins will enable accurate and sustainable pavement foundation designs.