Performance of 3-D geogrid-reinforced sand under direct shear mode

Recently, reinforcing materials in 3-D forms are getting more attention in the construction of reinforced soil structures. For the safe design and construction of these structures, it is essential to understand the interaction mechanism and behaviour of soil reinforced with 3-D reinforcements. In the present investigation, geogrid in 3-D form is used as the reinforcing material. Large-scale direct shear tests were conducted to study the interaction between sand and 3-D geogrid under direct shear mode. The medium and fine fraction of clean dried river sand was used in the study. Planar geogrids were also used to compare the effect of reinforcement form on the shear strength of reinforced sand. From the results obtained, it is observed that the interface shear strength of geosynthetic-reinforced sand greatly depends on the form in which it is used. Compared to planar geogrid, 16 and 22% improvement in interface shear strength was provided by medium sand reinforced with 3-D geogrids of triangular and rectangular pattern, respectively. The interface shear strength coefficient of 3-D geogrid-reinforced fine sand was less compared to 3-D geogrid-reinforced medium sand. However, provision of 3-D geogrid in fine sand gives an interface shear strength coefficient of 1.10 and 1.14 with triangular and rectangular pattern, respectively.