Investigation on the cyclic shear response of stereoscopic geogrid-reinforced coarse-grained soil interface

The investigation of cyclic shear interaction at the geosynthetic-soil interface is of great importance because it is ubiquitous in reinforced soil structures under seismic loading. Stereoscopic geogrids with different transverse-rib thicknesses (5, 10, 15, and 20 mm) were fabricated using the 3D printing technology. A series of large-scale cyclic shear tests were conducted at the reinforced interface for coarse grains with four particle size ranges (0.5-1, 1-2, 2-4, 4-8 mm) under different normal stresses (20, 40, and 60 kPa). The effects of the shear strength, vertical displacement, shear stiffness, and damping ratio were investigated. The results indicate that the peak shear stress at the stereoscopic geogrid-reinforced interface is greater than that of the planar geogrids in the particle size range of 2-4 mm. The vertical displacement increases with the transverse-rib thickness and particle size. The interface shear stiffness and damping ratio increase with the number of cycles, whereas the increment decreases with an increase in the transverse-rib thickness. The interface shear stiffness is larger when the ratio of the transverse-rib thickness to the particle size is 6.67. The shear strength of the coarse-grained soil interface under horizontal cyclic loading can be improved by thickening the transverse ribs of a planar geogrid to obtain a stereoscopic geogrid.