Lifetime prediction of geogrids for reinforcement of embankments and slopes

The failure of geogrids can be defined as an excessive creep strain, which causes the collapse of slopes and embankments. In this study, accelerated creep tests were applied to two different types of polyester geogrids, at 75, 80, and 85 °C by applying loads of 30 and 50% of the ultimate tensile strengths using a newly designed test equipment which allowed creep testing at higher temperatures. Then, the creep curves obtained were shifted and superposed on the time axis by applying time-temperature superposition principles. In predicting the lifetimes of geogrids, the underlying distribution of failure times was determined based on identification of the failure mechanism. The results indicate that the conventional procedures with the newly designed test equipment are shown to be effective in prediction of the lifetimes of geogrids with shorter test times. In addition, the predicted lifetimes of geogrids having different structures at various creep strains give guidelines for users to select the appropriate geogrids in the field.