A new approach to evaluate the long-term designing normal pressure of geonets using a short-term accelerated compressive creep test method

Designing normal pressures for geonet drainage materials were evaluated by using an accelerated compressive creep test method as SIM (stepped isothermal method). Also this study presents the results of compressive creep deformations beyond 100,000 h and the time–temperature superposition principle was applied to construct these creep master curves. Two types of geonet drainage materials, bi-planar and tri-planar type, were obtained from commercially produced lots. Transmissivity test was performed to aim at determining a performance limit normal pressure of geonets. From the results of the transmissivity test, the performance limit normal pressures were evaluated as 500 kPa and 1200 kPa for bi-planar and tri-planar geonet, respectively. Then Short and SIM compressive creep test were conducted to evaluate a performance limit strain at given pressure (500 and 1200 kPa) and to check the time to reach the performance limit strain for each geonet samples. Finally, from these compressive creep results, linear regression curves were constructed which can evaluate the designing normal pressures at any given service life time. And the result shows that the tri-planar geonet with unit weight of 1700 g/m2 has higher designing normal pressure (ex. 890 kPa for 35 years) compare to the bi-planar geonet (170 kPa for 35 years) with unit weight of 920 g/m2.