Height-dependent effects of geocell inclusions on the liquefaction strength of Zemmouri (Algeria) sand: evidence from undrained cyclic triaxial tests

This study investigates the effect of geocell reinforcement on the cyclic behaviour and liquefaction resistance of a sand from the seismically active region of Boumerdes, Algeria. Undrained cyclic triaxial tests were performed on Zemmouri sand, either unreinforced or reinforced with polyester geocells 12.5, 25, and 50 mm in height. Specimens at 30% relative density were subjected to cyclic stress ratios (CSR) of 0.30–0.40 under 50 kPa effective confining pressure. The results demonstrate that geocell inclusion improves the cyclic response of the sand, with the magnitude of improvement increasing with geocell height, with the enhancement directly correlated to the height of the geocells. The tallest geocells (50 mm) generated the most significant improvement, dramatically increasing the number of cycles to trigger liquefaction across all tested cyclic stress ratios. Reinforcement effectively curtailed excess pore pressure generation, reduced strain accumulation, and mitigated stiffness degradation. This is attributed to the enhanced radial mechanical confinement provided by the single cylindrical geocell, which restricts particle rearrangement. The findings indicate that geocell reinforcement, particularly at greater heights, can significantly enhance liquefaction resistance and improve seismic safety margins for infrastructure in liquefaction-prone zones.