Confinement effect of geocell on the mechanical characteristics of reinforced sand subgrade

Geocell has a confinement effect, limiting the deformation of soil and enhancing the strength of reinforced soil, and has a wide range of application prospects in traffic transportation subgrade engineering. To investigate the confinement effect of geocell on the mechanical characteristics of reinforced sand subgrade, this paper analyzes the macro-mechanical properties of reinforced sand subgrade using triaxial tests, investigates the micro-reinforcement mechanism employing discrete element method (DEM)-based simulations. The potential macro–micro linkages are studied. The experimental results revealed that the volumetric strain of the geocell-reinforced samples increased with the material’s elastic modulus, exhibiting a shear shrinkage phenomenon. The deformation pattern of the reinforced samples presented “segmental deformation,” which differed from that of the unreinforced sand samples. The geocell enhanced the cohesion intercept of the sand samples while having a minimal impact on friction angle. Through the analysis of numerical simulation results, it was found that the geocell constrained the displacement of the soil particles, altering the shear band development trend of the sample and resulting in “segmental deformation”. The geocell facilitated the concentration of force chains, enhancing their stability and resulting in improving the strength in the macro. Additionally, it was observed that the confinement effect of the geocell significantly reduced the fabric and force anisotropy of the granular soil, promoting consistent vertical alignment of force chains. This, in turn, enhanced the vertical force transmission capacity of the sample, explaining the micro-mechanism by which the confinement effect of the geocell increases the peak shear strength of the samples.