Experimental study on load bearing of geogrid reinforced cushion considering creep behavior

Creep is an inherent property of polymeric geogrids, which can significantly impact the safety and durability of reinforced soil structures, as it directly influences the effectiveness of the interface between the geogrid and soil. This study involved a series of creep tests on two types of biaxial geogrids to investigate their creep behavior. Four different constant loads were applied, each maintained for 1000 hours. The results indicated that for biaxial geogrids, the geogrid with a higher tensile strength experienced more creep deformation than the one with lower tensile strength at the same loading level. Furthermore, the geogrid fractured when the loading level reached 60% of its ultimate strength. To systematically investigate the influence of geogrid reinforcement and its creep characteristics on the mechanical performance of sand cushions, a series of large-scale model tests were conducted using a geogroove apparatus. The experimental program involved a comparative analysis of three types of cushion materials: unreinforced sand, sand reinforced with non-creeped geogrids, and sand reinforced with geogrids subjected to creep. The results demonstrated that the tensile strength of the geogrid plays a significant role in enhancing the bearing performance of the composite system. When subjected to appropriate tensile strain levels, the reinforced sand cushions showed marked improvements in bearing capacity compared to the unreinforced case. Quantitatively, two distinct geogrid-reinforced systems showed increases in load-bearing capacity of approximately 20% and 55%, respectively. However, the long-term deformation behavior (creep) of the geogrids was found to negatively affect the mechanical efficiency of the reinforcement, leading to a reduction in overall bearing capacity. Additionally, creep-induced changes were observed to influence the stress distribution within the cushion, alter the effective internal friction angle, and modify the overall stiffness response of the system.