Long-term pullout tests to analyse the soil-geogrid interaction

One of the most important aspects regarding the design of geosyntheticreinforced soil structures is to predict the long-term behaviour of reinforcements and interfaces. The paper describes a new large-scale laboratory apparatus capable of investigating the behaviour under pullout conditions of a geosynthetic reinforcement embedded in a compacted granular soil, and subjected to sustained tensile loading. By using the long-term pullout test results, the writers suggest a procedure for the determination of the interface parameter necessary to design the length of the reinforcement in the anchorage zone that can take into account the viscous effects of the polymeric material arising under serviceability conditions during the design working life.