Investigation of Failure Behaviour of Soil Nailed Excavations under Surcharge by Centrifuge Model Test

Abstract

A series of centrifuge tests were performed to evaluate surcharge effects on the behavior of nailed vertical excavations. The primary purpose was to observe the mechanism of failure surface development and to compare the test results with software results based on equilibrium limit analysis. In this experiment, four different surcharges were applied to both samples with and without nails. Applying surcharge and the following excavation were performed in 40 g acceleration. At the beginning of the test, the excavation was maintained using a water-filled membrane, right next to it. At the target acceleration, the surcharge was modelled by filling the loading tank over the sample with water, and finally, with water draining from the membrane, soil excavation was simulated. Eventually, failure surfaces resulted from the experiment were compared with the ones calculated by the equilibrium limit analysis-based software. Results revealed that the shapes of failure surfaces are bilinear in all tests and that the surcharge has its effects on the development of failure surfaces. In the meantime, the pull-out mechanism was observed in the nails during failure, with no bending. The equilibrium limit analysis also estimates the width of failure wedge well and its depth conservatively.