Centrifuge modeling of earth-reinforced retaining walls

This paper is on the centrifuge modeling of reinforced soil retaining walls with modular blocks facing. The influence of design parameters, such as length and vertical spacing of reinforcement, on the behaviour of the structure was investigated. A total of 11 models were tested, each one with different length of reinforcement or spacing. Each model was constructed and then placed in the centrifuge in order to increase gravitational acceleration up to 35 g, reproducing the soil behaviour of a 5-m high wall. Vertical and horizontal displacements were recorded by means of a laser profiler which enabled tracking of deformations in the structure along its longitudinal cross section, essentially drawing its deformed shape. As expected, the results confirmed reinforcement parameters to be the governing factor in the behaviour of reinforced soil structures since increasing length and reducing spacing improved structural stability. However, the influence of the length was found to be the leading factor that reduced facial deformations up to five times, and the spacing playing an important role especially in unstable configurations. The failure surface was characterised by the same shape (circular) and depth, regardless of the reinforcement configuration. Furthermore, the results confirmed the over- conservatism of design codes, since models with reinforcement layers 0.3H long showed almost negligible deformations. The test results may be used to set up further numerical modeling in order to investigate on other issues, such as the influence of the reinforcement stiffness and varying backfill.