Large-scale Tests on Bearing Capacity Failure of Geogrid-Reinforced Walls

Retaining structures are one of the most common applications of geosynthetic-reinforced soil (GRS). Most design approaches assume a multi-body failure mechanism below a quasi-monolithically reinforced block for the loss of bearing capacity in the foundation soil. Preliminary small-scale model tests showed that these assumptions are well justified and provided fundamental insights in the bearing capacity failure of GRS walls. However, the small-scale tests suffered from scale effects because the mechanical similarity was not completely fulfilled. Therefore, large-scale tests are additionally presented in this paper using regular geogrids. For this purpose, a 1.2 m high and 1.0 m wide geogrid-reinforced wall with a wrapped-around facing was installed on 2.0 m loose sand as subsoil. Then, a vertical load was applied on top of the reinforced structure. Horizontal and vertical wall deformations were recorded and the kinematic behaviour of the wall footprint at the bottom reinforcing layer was observed through a transparent side window using digital image analysis. Finally, the experimental data are compared to the results of analytical bearing capacity equations, revealing that the reduction of the reinforcement length needs to be considered to conservatively predict the load-bearing capacity.