The Function of Basal Geogrids in Minimizing Rutting of Geocell Reinforced Subgrades

Rutting is a common phenomenon encountered in flexible pavements supported by weak subgrades. Reinforcing the weak subgrades is one of the promising alternatives to alleviate the pavement surface rutting. This paper presents the results of laboratory model tests on a circular plate supported by geocell reinforced sand subgrades. A series of tests were carried out by varying the height of the geocell mattress with an additional layer of basal geogrid placed underneath the geocell mattress. The surface settlements (rutting) were measured through displacement gauges. Strain gauges were placed along the width of the basal geogrid to verify their performance as a base layer. A substantial reduction in surface rutting is observed in the case of geocell reinforced beds with basal geogrids. A seven fold improvement in bearing capacity was obtained with the provision of an additional geogrid layer over unreinforced subgrades. Overall, a basal geogrid layer provides higher structural support mobilized through membrane effect to the geocell reinforced pavement layers.