Test and DEM study on cyclic hysteresis characteristics of stereoscopic geogrid–soil interface

The bearing resistance provided by the geogrid's transverse ribs is a non-negligible aspect of the strength mechanism in mobilizing the geogrid–soil interface. Therefore, studying its influence on the response mechanism of geosynthetic-reinforced soil structures under cyclic loading is crucial. The stereoscopic geogrids were manufactured using 3D printing technology by quantitatively thickening the transverse ribs of planar geogrids. To investigate the cyclic hysteresis relationship and stress–dilatancy phase-transformation characteristics of the stereoscopic geogrid–coarse particle interface, cyclic direct shear tests were conducted. Additionally, a discrete element method (DEM) was employed to study the evolution of shear bands and fabric anisotropy at the interface under cyclic loading. The results of the study indicate that the stress–displacement phase angle of the stereoscopic geogrid in the horizontal direction of cyclic shear is smaller compared to the planar geogrid. Furthermore, thickening the transverse ribs decreases the stress–dilatancy phase-transformation angle of the interface. The thickness of the interface shear band in the stereoscopic geogrid is greater than that of the planar geogrid. Moreover, as the transverse-rib thickness increases, the principal direction of the average normal contact force and average tangential contact force under cyclic loading also increases.