Analysis of forces and displacements leading to failure of different configurations of soil-nailed excavation centrifuge models under cyclic loads

To attain comprehensive understanding of the development of displacements and forces leading to failure of oil-nailed excavation structures under seismic loads the results from tests on 12 centrifuge models subjected to cyclic shaking were analyzed in detail. The testing itself and data collection were done in a previous investigation. Comprehensive and systematic analysis of the test results revealed two types of failure surfaces and corresponding failure mechanisms, evolution of displacements and failure surfaces, and the role of the nails in the overall behavior and stability. To accurately evaluate the forces involved and subsequently develop methods for the evaluation of stability and prediction of displacements several elements of the centrifuge models were tested. The centrifuge test data and observations along with the results of this additional testing were then used to evaluate the applicability of the pseudo-static limit equilibrium method in assessing the models stability and to develop a new model and associated method and computer code for the calculation of cyclic, incremental displacements of soil-nailed mass during dynamic shaking. The method for the calculation of displacements utilizes the information that can be easily obtained during the construction of the soil-nailed excavations. Both the results of the limit equilibrium analysis approach and the above method for displacements prediction are in a very good agreement with the measurements and observations from centrifuge testing. Such approach and method can be therefore very useful in the current engineering practice.