Hydro-mechanical behavior of geogrid reinforced soil barriers of landfill cover systems

This paper examines the hydro-mechanical behavior of soil barriers with and without the inclusion of geogrid reinforcement within the soil barrier of landfill cover systems. The effect of geogrid type on the deformation behavior of the soil barrier subjected to various ranges of distortion levels was examined through centrifuge tests carried out at 40 g. An overburden pressure equivalent to that of landfill cover systems was applied to all the soil barriers tested in this study. The performance of the soil barrier with and without geogrid layer was assessed by measuring water breakthrough at the onset of differential settlements during centrifuge tests. Un-reinforced soil barriers of 0.6 m and 1.2 m thickness were observed to experience single narrow cracks penetrating up to full -depth of soil barriers at distortion levels of 0.056 and 0.069 respectively. In comparison, soil barriers reinforced with geogrids restrained cracking better than unreinforced soil barriers. However, degree of restraining of cracks in the soil barriers was found to be strongly depending on the geogrid type and the thickness of the soil barrier. Limiting distortion levels for 0.6 m and 1.2 m thick soil barriers reinforced with a low strength geogrid was found to be 0.095 and 0.108 respectively. When the soil barrier of both thicknesses was reinforced with a geogrid having relatively high tensile load-strain characteristics, the integrity of the geogrid reinforced soil barrier was observed to be retained even after inducing a distortion level of 0.125. The results from the present study suggest that the hydro-mechanical behavior of the soil barriers can be improved with a suitable geogrid layer having adequate tensile load-strain characteristics. (C) 2010 Elsevier Ltd. All rights reserved.