A STUDY ON MECHANISTIC-EMPIRICAL DESIGN OF FLEXIBLE ROAD PAVEMENT AND OVERLAY USING METHOD OF EQUIVALENT THICKNESS

Abstract

This project develops a mechanistic–empirical framework for designing flexible pavements by integrating stress, strain, and deflection criteria across multi-layered systems. The research focuses on improving weak natural subgrades through compacted subgrade layers, optimizing pavement thickness for low- and high-volume roads, and extending service life under repeated axle loads. Using Odemark’s transformation and Boussinesq’s theory, the work evaluates effective California Bearing Ratio (CBR), vertical compressive strain, and radial tensile strain to determine layer thicknesses. Comparative analyses reveal that strain-based criteria generally require thicker compacted subgrades than stress-based methods, particularly up to 50 msa load repetitions. The study also proposes optimization models for bituminous and granular layers, perpetual pavement design, and overlay thickness estimation, validated against IRC:37-2018, IITPAVE, and KENPAVE outputs. Results demonstrate strong convergence with existing guidelines while highlighting the sensitivity of granular layers to rutting performance. Additionally, residual pavement life prediction is achieved through surface deflection analysis, offering practical tools for maintenance planning. The integration of computational algorithms in PYTHON, MATHEMATICA, and JAVA provides user-friendly GUIs for engineers, ensuring reliable and cost-effective pavement design. Overall, the findings emphasize revisiting fixed-thickness recommendations and adopting mechanistic–empirical approaches for sustainable, durable, and optimized pavement structures.