Model studies of multi-edge footings on geogrid-reinforced sand

The ultimate bearing capacity of multi-edge shallow footings on loose and dense sand bed with and without geogrid reinforcement has been investigated. The data used have been obtained from extensive series of laboratory model tests. A total of 140 laboratory model tests were carried out using four different model rigid plates with the shapes of +, H, T and square. Parameters of the testing programme include the density of sand soil, depth of first reinforcement, vertical spacing of reinforcement layers, number of reinforcement layers and the covering of the reinforcement layer. Bearing capacity ratio was defined to evaluate improvement performance. The results indicate that the use of geogrid layers in sand bed has considerable effects on the bearing capacity characteristics and the optimum reinforcement parameters are independent from the shape of the footings. The construction of geogrid reinforcement helps in redistributing the applied load to a wider area. It has been observed that the use of geogrid reinforcement in sand layer provides additional improvement of bearing capacity of the multi-edge footings up to four times that of the unreinforced case.