Comparison of Field and Laboratory Pullout Tests on Geosynthetics in Marginal Soils

Abstract

The increasing use of geosynthetics to reinforce soils in many geotechnical engineering applications requires better evaluation of the soil–geosynthetic interface properties for use in the design and analysis of the different reinforced soil structures. The soil–geosynthetic interaction can be determined from direct shear tests or pullout tests. Until now, most research was focused on investigating the interface properties between geosynthetics and granular materials. Interest has increased in the use of marginal soils as backfill materials in mechanically stabilized earth (MSE) walls and embankments because of the cost-effectiveness of using the available cohesive soils. This strategy requires the evaluation of interaction parameters between geosynthetics and marginal soils. For this purpose, a series of laboratory and field pullout tests was carried out with different types of geosynthetic reinforcements in marginal silty clay soil of medium plasticity. Four types of geogrids and three types of geotextiles were used in this study. Laboratory and field pullout tests were compared. The coefficient of interaction (C_i) between geosynthetics and cohesive backfill, the variation of pullout design parameters (F*, α) with overburden depth, and the shear stress distribution along the reinforcement specimen also were evaluated.