Study on creep properties of geosynthetics under CBR puncture load

Creep behaviour is highly significant for the long-term engineering applications of geosynthetics. Besides tension, geosynthetics could be subjected to puncture or tearing in field applications. To investigate the creep properties of geosynthetics under puncture loading, this study developed a novel CBR puncture creep test setup. A series of puncture creep tests and creep rupture tests were conducted on four representative geosynthetic materials. The puncture creep reduction factors were calculated under different puncture creep strains, and compared with conventional tensile creep reduction factors. An equation was established to predict the puncture creep reduction factor. The test results show that the puncture creep strain displays significant time-dependent variations and is most pronounced in the geomembrane; under incremental loading, the puncture creep strain rate significantly increases; the puncture creep reduction factors for various geosynthetics are consistently higher than conventional tensile creep reduction factors. Regression modelling indicates a strong correlation between the puncture creep strain and the puncture creep reduction factor while the influence of the design life is negligible. To improve the safety and durability of the engineering structures, it is recommended to adopt the puncture creep reduction factor for designing geosynthetics under puncture load.