Enhancing the bearing capacity of unpaved roads on soft clay subgrade using geogrid reinforcement with a triaxial configuration

This study evaluated the performance of unpaved roads reinforced with triaxial geogrids over soft clay subgrades. The experimental setup involved a fully instrumented road model with a 0.05–0.2-m-thick crushed rock base and a 0.8-m-thick soft clay subgrade, with the geogrid positioned between the base and subgrade. Plate bearing tests were conducted to determine the ultimate bearing capacity and failure modes. Results showed that the geogrid-reinforced base with a thickness of 0.20 m achieved the highest ultimate bearing capacity of 1040 kPa, a 44 % improvement over the unreinforced base (720 kPa). The reinforced section with a reduced thickness of 0.15 m still exhibited an improved ultimate bearing capacity of 860 kPa, demonstrating that the geogrid reinforcement significantly enhances load-bearing capacity and reduces settlement in unpaved roads over soft clay subgrades, with optimal performance observed at a base thickness of 0.20 m, with an enhancement factor of 1.44.