Experimental and Numerical Simulation Studies on the Interface Characteristics Model of Loess and Bamboo Geogrid

The widespread loess in western China poses significant challenges to transportation infrastructure construction due to its water sensitivity and collapsibility. This study investigates the interface mechanical properties of bamboo geogrid-reinforced loess under static loading through large-scale indoor pull-out tests and DEM–FDM coupled numerical simulations. The effects of vertical stress, the pull-out rate, the number of transverse ribs, burial depth, and reinforcement material on interface behavior were systematically evaluated. Results show that peak pull-out force increases with vertical stress, the number of transverse ribs, and burial depth, with all curves exhibiting pronounced strain hardening followed by softening characteristics. The pull-out rate exhibits a non-monotonic effect, with peak resistance higher at both lower and higher rates compared to intermediate rates. Bamboo geogrids demonstrate substantially superior performance over geogrids, with approximately four times higher peak pull-out resistance and greater initial stiffness. Numerical analysis reveals increased porosity and decreased coordination number in the grid vicinity, the horizontal stratification of the slip rate along the reinforcement, and concentration of strong force chains ahead of transverse ribs, elucidating the model-derived mechanisms underlying the macroscopic reinforcement effects. The findings confirm that bamboo geogrids provide effective and sustainable reinforcement for loess subgrades, offering a scientific basis for environmentally friendly engineering applications in loess regions. Although potential long-term durability under field environmental conditions requires further verification, the superior mechanical interface performance demonstrated here positions treated bamboo geogrids as a promising sustainable reinforcement option.