Prediction Models for Computation of Deformations and Interface Stresses in a Two-Layered Pavement Structure

The granular layer, being the major structural component in low-volume roads, exhibits significant plasticity and undergoes both elastic and permanent deformation under repeated vehicular loading. Stress-dependent, nonlinear resilient moduli, as well as elastoplastic models, have been considered for characterizing individual pavement materials; however, very limited research is available that studies the composite behavior of granular material and subgrade soil in two-layered pavement structures. In the present study, a single-lane low-volume road was considered and critical pavement responses, that is, surface and interface deformations, and interface stresses were examined for different modular ratios and pavement thickness–tire width ratios. The elastoplastic Drucker–Prager model was considered in a finite-element analysis for simulating both the elastic and plastic aspects of granular materials. The results indicated that elastoplastic characterization of the granular layer and multiple-wheel loads made a significant difference in the responses of pavements with thin granular layers and low modulus ratios; however, its influence reduces with increases in the thickness of the granular layer at a constant modulus ratio. For a constant pavement thickness, relatively greater deformations were obtained at higher modulus ratios, which indicated that pavement responses depended on the composite behavior of the pavement system rather than the strength of an individual layer. Based on the variation in deformations and interface stresses with the modulus ratios and pavement thickness–tire width ratios, prediction models were developed that can be utilized for predicting surface and interface deformations, and interface stresses for the analysis and design of a two-layered pavement structure.