Predicting the Creep Behavior of Polypropylene Geogrid Using Temperature-Accelerated Stress Relaxation Test Results

Geosynthetic-reinforced soil (GRS) structures have become increasingly popular in recent times. One major concern with these structures is the possibility of creep rupture failure in the geosynthetic reinforcement. Typically, conventional creep tests are used to evaluate the creep behaviour of polymer geosynthetic reinforcements, but this method is known to be time-consuming. To address this issue, a technique
was introduced that uses an increase in ambient temperature to accelerate the development of creep strain. The results can be analysed using a time-temperature superposition (TTS) method, which allows for a short-term temperature-accelerated creep test (~24 hours) to be analysed to achieve an equivalent long-term creep behaviour. Furthermore, it has been found that the creep behaviour of geosynthetic reinforcement can also be predicted from its stress relaxation behaviour. The aim of this research is to combine both techniques to accurately predict creep behaviour for a much longer time from a short-term stress relaxation test. To achieve this, a series of short-term temperature-accelerated creep tests and stress relaxation tests were performed on a polypropylene geogrid. TTS techniques were then used to predict the respective long-term creep and stress relaxation behaviours. A framework for converting creep behaviour from stress relaxation behaviour was developed. The study found that by performing a temperature-accelerated stress relaxation test for a total of 12 hours, the long-term time history of stress relaxation could be accurately predicted for 115 hours. This information could then be converted using the developed framework to predict the long-term time history of creep for 348 hours. This means that the time required to perform the conventional creep test could be shortened by a factor of 29.