Soil-geogrid interaction in pullout conditions: influence of soil moisture content and density

Abstract

Geosynthetics, including geogrids and geotextiles, have been extensively used for stabilisation and soil reinforcement in several geotechnical structures, such as foundations, abutments, walls and slopes. In these applications, soil-geosynthetic interaction plays a determinant role. This paper describes an experimental study carried out using a large-scale pullout test device aiming to investigate the interaction between a granite residual soil and a uniaxial extruded geogrid. To analyse the influence of soil moisture content on the interface behaviour, the soil was tested dry and at the optimum and half of the optimum moisture contents. To simulate distinct degrees of compaction in the field, the soil was compacted to different values of dry unit weight and its influence on the soil-geogrid interface behaviour was also evaluated. Test results have demonstrated that soil moisture content can significantly affect the geogrid pullout resistance, particularly when the soil is compacted with lower density. Furthermore, the failure mode at the interface (i.e., geogrid tensile failure or pullout failure) was found to be highly dependent on the soil density.