Experimental study on the pullout characteristics of toothed warp knitted geogrid in different sand fillers

In order to investigate the pullout characteristics of a toothed geogrid, a commercialized warp-knitted geogrid was combined with rigid angle aluminum to form a qualified toothed geogrid and used to perform pullout model tests in which four different gradations of fillers, three denti-strip heights, and three normal stress levels were adopted. The research shows that: 1) at the initial stage of the pullout test, pullout resistance rises rapidly and only the curves of the pullout force (T) and pullout displacement (△L) under lower normal stress reach the peak. The maximum pullout resistance is positively related to normal stress on the model, the denti-strip height, and the coarse particle content. 2) As the denti-strip’s height increases, the coefficient of the reinforcing effect, the quasi-shear strength parameters, and the quasi-frictional coefficient all show enhancements to some extent, as well as the drawing coefficient. When the normal stress rises, the quasi-shear strength parameters increase, while the quasi-frictional coefficients gradually decrease. The quasi-shear strength parameters and the quasi-frictional coefficient are positively correlated with the coarse particle content, while the drawing coefficient has a negative correlation with the coarse grain proportion. 3) It could be inferred that the denti-strip with a suitable height and coarser gradation of the filler would be beneficial to enhance the anti-pullout performance in reinforcement project entities, and the bearing resistance acting on the denti-strip is able to play a more dominant role in a low backfill condition. The research results can further enrich the relevant achievements in the field of spatial reinforcement and provide useful evidence for the design and construction of related projects, especially for low embankment filling.