Experimental and numerical studies on the reinforcing mechanisms of geosynthetic-reinforced granular soil under a plane strain condition

Geosynthetics have been widely used in the construction of reinforced soil structures and yet the reinforcing mechanisms of geosynthetics have not been fully understood. Eight biaxial compression model tests of geosynthetic-reinforced soil (GRS) were conducted in this study under a plane strain condition to investigate the reinforcing mechanisms of geosynthetics. Membrane was used as reinforcement material and aluminum rods were used to simulate the granular backfill soil. Three influencing factors were considered in the model tests including reinforcement spacing, reinforcement stiffness, and gradation of backfill soil. This study also conducted a numerical analysis using a discrete element method (DEM) model. The DEM model was calibrated and verified by geosynthetic tensile test, angle of repose test, biaxial test, and model test results of the GRS masses. The piecewise linear model was used in the numerical model to simulate the nonlinear characteristics of the geosynthetic under tensile load. A parametric study was conducted to obtain further detailed insights into the reinforcing mechanisms of geosynthetics. Results of the model tests and the numerical simulations indicated that reinforcement spacing had strong effects on the behavior of the GRS mass. The dilation of the backfill soil was suppressed by reinforcement and the suppression was enhanced by increasing reinforcement stiffness and reducing reinforcement spacing. The reinforcement spacing played a more important role in the behavior of the GRS than the reinforcement stiffness. Geosynthetics reinforcement could restrain the development of vertical settlements along the height of the GRS mass. In addition, the geosynthetic reinforcement had a function of dispersing vertical applied pressure and the stress induced by loading was more uniformly distributed in the GRS mass as compared with unreinforced cases. Increasing reinforcement stiffness had little effect to improve the dispersion function of geosynthetics. The reinforcing effects in the GRS mass backfilled with soil of low strength were more significant compared to that in the GRS mass backfilled with soil of high strength. (C) 2020 Production and hosting by Elsevier B.V. on behalf of The Japanese Geotechnical Society.