Dynamic failure mechanism of soil-nailed excavation models in centrifuge

To assess the behavior and stability of soil-nailed excavations during strong earthquakes, the kinematics and failure mechanism of four soil-nailed excavation centrifuge models subjected to horizontal cyclic loading are analyzed. The experiments revealed that the failure mechanism was similar in each test and occurred in two well-defined phases. Initially, the nails along the bottom row acted as anchors, causing the soil-nailed mass and facing to rotate about their connection with the facing. Subsequently, when the pullout capacity of the bottom row of nails was exceeded due to continued strong horizontal shaking, the nailed soil mass and facing moved laterally in cyclic increments by sliding on an approximately bilinear failure surface. If the duration of the shaking was long enough, large displacements eventually caused total collapse of the models. Large amplitudes of horizontal accelerations were required to initiate significant displacements of the nailed soil mass in the centrifuge models, thus indicating that prototype soil-nailed systems should be very stable during strong earthquakes. The experiments clearly demonstrated that an increase in the nail length resulted in an increase in the soil-nailed model stability.