Tunnel–piled structure interaction: Numerical simulation of hybrid centrifuge tests

Abstract

Tunnel excavation in urban areas causes ground movements that could damage existing nearby piled structures. Geotechnical centrifuge modelling has been widely used as a tool to study problems related to tunnelling activities and its interaction with existing infrastructure systems. Recent hybrid centrifuge tests using the Coupled Centrifuge-Numerical Modelling (CCNM) approach have provided high-quality experimental data of soil–piled structure interactions in dry sand, demonstrating the role of structure stiffness on head load transfer among piles and the subsequent impact on pile shaft resistance with tunnel volume loss. This paper extends the experimental data set with a finite element numerical analysis of the problem, providing additional insights into the complex interactions. An advanced hypoplastic constitutive model was adopted for the soil and, to enable appropriate comparison of numerical and experimental results, the conditions within the centrifuge tests were replicated numerically. Despite some discrepancies between numerical and experimental results, in particular related to limitations of the adopted soil–pile interface model, results from the numerical simulations are shown to broadly agree with the centrifuge test data. Numerical analysis results are used to explore the effect of tunnelling on pile settlements and the development of radial stresses around piles, as well as the stress paths at the soil–pile interface. These data provide additional insights to complement and extend current understanding of the complex soil–pile interactions taking place.