European experience in pullout tests: The influence of geogrid’s geometry and structure on interface behavior

This paper deals with some results of a wide experimental research carried out in order to study factorsaffecting cyclic and post-cyclic pullout behaviour of different geogrids embedded in a granular soil. Thenew test procedure developed (multistage pullout test) and the relative results are described. Inparticular, test results obtained using the constant rate of displacement (CRD) and the multistage pullouttests highlighted the influence of the different factors involved in the research (cyclic load amplitude andfrequency, vertical confining stress, geogrid tensile stiffness and structure) both on the peak pulloutresistance and on the peak apparent coefficient of friction mobilized at the interface.