Effects of Moisture on the Mechanical Behavior of Sand–Geogrid: An Experimental Investigation

Soil–geosynthetic interaction is a key factor for designing and analyzing reinforced soil structures. In this investigation, the effect of different moisture content on the behavior of soil–geogrid interfaces is evaluated using direct shear and pullout tests. The results are presented and discussed in terms of direct shear and interface shear behavior, the frictional resistance of interfaces, efficiency factor, pullout resistance, pullout behavior, and apparent friction coefficient. The results revealed that a decrease in moisture content resulted in an increase in the both interface friction angle and adhesion of specimens. Moreover, the interface friction angle of sand–geogrid specimens in pullout tests was higher than that of direct shear tests. According to interface shear results, the efficiency factors ranged from 0.87 to 0.99. Based on pullout results, the apparent friction coefficient was found to be in the range of 0.77–1.72.