Effects of geogrid reinforcement on the static liquefaction behavior of granular fill by triaxial test method

Abstract

Replacing the existing weak soil by granular fill material (partial or full) is one of the conventional stabilisation technique to improve the bearing capacity and liquefaction behavior of the soil. However, in many cases the depth of replaced granular fill becomes very thick, thus lead to the excessive cost. In the solution to this problem an experimental investigation was initiated to evaluate the effect of geogrid reinforcement on the static liquefaction resistance of granular fill obtained from Karaikudi, Sivagangai District, Tamilnadu, India. An experimental program through triaxial compression was conduct and with various investigation on geogrid layers confining pressures. It was observed that the extensile force of the geogrid gradually contributes to the improvement of the reinforced specimens shear strength and the extensile force increased with the increase in the number of geogrid layers, as a result the failure mode changed from shear band to bulging. The installed geogrid layers in the granular fill improved the stress-strain response in terms of increase in peak deviatoric stress and decrease in failure strains. In addition, the extensile force provides better interlocking property to the granular fill be arranged between the geogrid, leading to the decrease in the pore water pressure. Under a confining pressure of 150 kPa the pore water pressure of the un-reinforced specimen was about 117 kPa, whereas the granular fill reinforced with one, two and three layers of geogrid achieved the pore water pressure of 97.5 kPa, 76.5 kPa and 49.5 kPa, respectively, which are 20.12 %, 52.94 % and 136.36 %, lower than that of the un-reinforced specimen. The findings conclude that the geogrids considerably influence the shear behaviour of granular fill, and the geogrid reinforcement improves the interlocking strength of the granular fill, thus improving its shear strength.