Numerical Simulation of Geogrid-Reinforced Soil Barriers Subjected to Differential Settlements

A numerical simulation of centrifuge model tests was carried out to develop an understanding of the behavior of geogrid-reinforced soil barriers (GRSBs) of landfill covers subjected to differential settlement. The influence of the axial stiffness of the geogrid, soil-geogrid interface friction, overburden pressure, and thickness of the soil barrier on the overall performance of GRSBs was investigated. Results from the study indicate that unreinforced soil barriers (URSBs) experience tensile stresses and strains throughout their thickness at the zone of maximum curvature; however, with the inclusion of geogrid within the soil barrier, the depth of the tension zone was found to be reduced significantly. A significant reduction in the magnitude of tensile stresses and strains in particular below the location of the geogrid was noticed with an increase in the axial stiffness of the geogrid. The results demonstrate that the geogrid layer mobilizes higher tension and thereby transfers lesser bending stress to the portion of soil barrier placed below the geogrid layer. The magnitude of the mobilized tensile load of the geogrid was found to be directly proportional to the magnitude of the axial stiffness of the geogrid, overburden pressure, and thickness of the GRSB. The normalized depth corresponding to zero horizontal tensile stress was found to decrease with an increase in the axial stiffness of the geogrid, which indirectly suggests that the depth of tension cracks can be considerably reduced with an increase in axial stiffness of the geogrid. This study also suggests that the integrity of GRSBs subjected to differential settlements can be retained only when a geogrid having adequate tensile load-strain characteristics along with an adequate overburden pressure is provided. The results of numerical analyses of GRSBs subjected to differential settlements were observed to corroborate well with the physically observed centrifuge test results. (C) 2014 American Society of Civil Engineers.