A simple method to evaluate the pullout resistance of extruded geogrids embedded in a compacted granular soil

Pullout tests are necessary in order to study the interaction behaviour between soil and geosynthetics in the anchorage zone; hence, the resulting properties have direct implications on the design of reinforced soil structures.Several experimental studies showed the influence of different parameters (reinforcement stiffness, geometry and length, applied vertical effective stress, and geotechnical properties of soil) on the peak and on residual pullout resistance.On the basis of the results of the tests carried out by Moraci and Recalcati [2005. Factors affecting the pullout behaviour of extruded geogrids embedded in a compacted granular soil. Geotextiles and Geomembranes, submitted for publication], a new theoretical method was developed to determine the peak and the residual pullout resistance of extruded geogrids embedded in a compacted granular soil. The method is capable of evaluating both the bearing and the frictional components of pullout resistance, taking into account the reinforcement extensibility and geometry as well as the non-linearity of the failure envelope of backfill soil. The comparison between theoretical and experimental results was favourable, thus confirming the suitability of the proposed approach.