Behavior of geogrids under pullout tests in fine and coarse soils

This paper presents an analysis of the behavior of geogrids when subjected to pullout tests in the field and in the laboratory. Different types of soils were considered, ranging from silty clay to coarse sand. The field work was associated to a 1700m long, 5m high soil wall reinforced with geogrids. The wall constitutes the upper part of a dike constructed for containing bauxite residues and was constructed using a residual silty-clay. A 2.6m high experimental fill was also constructed for performing 16 large-scale pullout tests. Horizontal loads and displacements were monitored during these pullout tests. In the laboratory, a large dimension pullout apparatus was used for testing the polypropylene and polyester geogrids, which exhibited distinct physical and mechanical stiffness and strength characteristics. The geogrids were instrumented with horizontal displacement gages (tell-tails) and strain gauges, placed on different positions along the grid's length. Silty-clay and sand were used in the experimental program. Conventional laboratory tests were conducted for defining the strength and deformability parameters of both the soil and the geogrid.