Response of a model footing reinforced by novel three-dimensional elements

In this study, a new three-dimensional (3D) reinforcement element, comprising a horizontal ring connected to vertical legs, is introduced. A series of 1g laboratory-scale tests was conducted on a circular footing that rested on a sand bed containing planar or new 3D reinforcements. The effects of depth of the first layer, reinforcement configuration number and spacing of layers are reported. Tests were performed on discrete or contiguously attached elements. The new 3D elements were examined with either upward- or downward-facing legs. An improvement of about 16% was achieved by the upward-legged contiguous 3D elements over the performance delivered by planar contiguous elements. Also, the results show that the vertical legs are capable of exerting passive forces on the soil and increasing the stiffness and bearing capacity of the composite system, but the contributory effect is more pronounced for the upward-leg configuration. Finally, 17 and 26% improvements were achieved, respectively, for two planar and two 3D-reinforcement layers when compared with that of a single layer. The concept of planar reinforcement connected to vertical legs, could be adapted for developing a more efficient generation of reinforcement, such as geogrids with vertical ‘legs’, to take advantage of the passive resistance generated by ‘legs’.