Pullout resistance of geogrid reinforcement with in-plane drainage capacity in cohesive soil

This study presents the results of geogrid pullout tests conducted in wet and fine-grained soils. Failures of reinforced soil structures have often involved inadequate drainage due to the use of fine-grained soils, which has led to stringent specifications for backfill material in such structures although there are significant economic reasons for relieving the specifications. One approach to improve the issue is to reinforce fine-grained soils with geosynthetic providing both reinforcement and lateral drainage. Although using reinforcement with in-plane drainage capability is conceptually promising, transmissivity requirements for this application have not been properly evaluated. Pullout tests were conducted on cohesive soils using geogrids with the same tensile strength but with and without in-plane drainage channels. The results indicate that geogrids with in-plane drainage layers show higher pullout resistance than conventional geogrids. The finding contributes to promoting the use of poorly draining soils as backfill material.