Mechanistic-Empirical Design of Low Volume Flexible Road Pavement by Limiting Vertical Interface Stress and Strain on Subgrade

The low volume rural road pavement is designed with unbound granular layers only which may be designed against rutting. The objective of present paper is to estimate the thickness of granular base layer of pavement based on mechanistic-empirical approach. In present analysis, the pavement has been considered as multi-layered system. Odemark's method has been used to transform the multi layered system into an equivalent single layer homogenous medium. In order to estimate the vertical interface stress and strain on the top of natural sub-grade, Boussenesq's theory has been used. For estimation of granular base and sub base thickness, the allowable stress and strain on subgrade have been considered from Huang's corelation and recommendations from IRC:37-2018.The pavement thickness thus obtained using present stress and strain based approach have been compared with thickness obtained using AASTHO guideline and IRC:SP:722015, the guidelines based on loss in serviceability of road pavement. However, comparison of results show good agreement in higher subgrade CBR range in stress based present approach whereas the strain based approach shows better convergence with lower range of subgrade CBR. In this backdrop, proposed method may be considered as an acceptable and reliable approach for estimation pavement thickness for low volume granular road pavement.