Effect of surcharge magnitude on soil-nailed wall behaviour in a geotechnical centrifuge

Abstract

The current research was undertaken to study the effect of surcharge magnitude on soil-nailed wall behaviour by modelling an excavation using a geotechnical centrifuge and analytical software. An acceleration of 50g was applied to the models in the geotechnical centrifuge and the excavation was modelled in an in-flight centrifuge at 50g by lowering the saltwater level inside a transparent Latex container in front of the soil-nailed wall. Changes in the safety factor (SF) and stability of the soil-nailed wall were investigated. Next, the centrifugal acceleration was increased to 80g in 5g increments and the effect on the parameters was determined. An increase in centrifugal acceleration (N) was found to decrease the SF of excavation gradually until it reached the stability limit (SF = 1), which is the failure initiation criterion. The occurrence of failure in the physical model agreed with the pattern developed in the numerical models and illustrates and verifies the accuracy of models. Nail density (Dn) is introduced as a functional parameter having a major role on the performance of soil-nailed walls. An empirical relation is developed between the external stability SF and the deformation components which can be normalised using the value for nail density.