Modeling of Semi-mechanistic approach for Geo-synthetic Reinforced Flexible Pavement Design

Reinforced flexible pavement is being constructed to increase pavement service life and make optimal use of geosynthetics. Appropriate selection of geogrid stiffness within the asphalt concrete layer and proper choice of subgrade materials may lead to a workable solution. Rut depth estimation under the various contact pressure with the varying subgrade modulus is the best approach to identifying the suitable geogrids range. A 2D axis-symmetrical numerical model was developed to simulate the typical pavement response under heavy traffic loading. Elasto-plastic behavior of soil material was considered for the base and subgrade layer. Initially, the developed numerical model was validated with the published experimental simulations, and the obtained numerical results are in good agreement with the experimental results. Further, this study presents the estimation of rut depth for the various subgrade modulus, cyclic wheel loading, and geogrid stiffnesses from the numerical simulations. The results show the beneficial effect of the appropriate range of geogrid stiffness in the asphalt concrete layer. Qualitative discussions are made from parametric analyses on the variation of vertical surface deformations of reinforced flexible pavements under repeated wheel loading. The results indicated that the rut depth increased for pavements with a lower subgrade modulus. However, this study observes a significant reduction in pavement's rut depth with varying geogrid stiffness from 100 kN/m to 400 kN/m. Thus, selecting geogrid with a stiffness greater than 400 kN/m is advisable for the better long-term performance of the pavements having lower subgrade modulus.