Direct Shear Behavior of Three-dimensional Geogrids-soil Interface with Different Square Apertures under Various Shear Rates

For reaching the influence of the aperture of the three-dimensional geogrids with enhanced transverse ribs on the interface behavior, three geogrids with different square apertures were made by 3D printing technology. Effect of the square apertures (25 mm×25 mm, 35 mm×35 mm, 45 mm×45 mm), vertical stresses (20, 40, 60 kPa), shear rates (0.5, 1, 2 mm/min) were investigated by large scale direct shear test. The results show that the peak shear stress and friction angle of the interface between the geogrid with aperture of size 35 mm×35 mm and soil are greater than others; as the shear rate increases doubly, the peak shear stress changes less, and the rate of peak shear stress change at different shear rates is between −4% and 11%; the greater the vertical stress, the greater the peak shear stress, and the rate of peak shear stress change is greater than 20%, indicating that the vertical stress has obvious effect on the shear character of the interface of reinforced soil.