Mesoscopic pullout behavior of geosynthetics–sand–clay layered reinforced structures using discrete element method

The geosynthetics–sand–clay layered reinforced (GSCLR) structure has wide application prospects due to its massive adoption of the clay. To date, the coordination between the geosynthetics, sand, and clay is not thorough enough. In light of this, a series of discrete element method models were established for the pullout behavior of a GSCLR structure. The mesoscopic parameters such as the displacement vector, the contact force chain, and the local porosity were analyzed, and the mechanism for the load transfer between the geogrid, sand layer, and clay layer was examined. The thickness and porosity of the sand layer were also considered as the variables. The effects of the various factors on the strength index of the geogrid–sand interface were analyzed. The results showed obvious differences in the movement trend and mesoscopic parameters changes of the sand and clay layer in different regions. The thickness of the shear bands generated in the sand layer was affected by the upper and lower clay layers. At the same pullout displacement, the ultimate pullout resistance of the GSCLR structure did not enlarge continuously with an increase in the thickness of the sand layer, and there was an optimal thickness of the sand layer.