Model study on the failure mechanism of soil-nailed structure under surcharge loading

To investigate the effects of surcharge loading on the failure mechanism of soil-nailed structures, reduced scale-model tests were performed. The main variables for this study were the bending stiffness and tension resistance of nails and applied surcharge loading levels. In addition, two different testing sequences were used to simulate, respectively, the application of soil nailing in both new construction and rehabilitation or widening of earth-retaining systems under surcharge loading. To effectively assess the loading effects on the failure mechanism, failure tests without surcharge loading were performed, and the results were used as reference data. When applying surcharge loading, the failure of the system occurred through a progressive breakage of the nails initiated at the top nails. Under low surcharge loading, the state of stress in the upper nails is close to the stress state for the unloaded wall. As the surcharge loading increases, the equivalent earth pressure coefficient in the upper nails tends to increase toward the at-rest value. The locus of nail breakage points under surcharge loading is fairly close to that obtained with flexible nails without surcharge loading regardless of bending stiffness and construction sequence.