Centrifuge modelling of tunnelling induced ground displacements: pressure and displacement control tunnels

Abstract

Predicting the impact of tunnelling-induced ground movements on existing foundation systems or infrastructure is an important stage during tunnel design or risk assessment processes. Centrifuge modelling has been used extensively as a tool to study soil movements caused by tunnelling and their interactions with existing structures. In 2D plane-strain centrifuge models, tunnel volume loss can be simulated in a variety of ways, but is conventionally done using a fluid-filled flexible membrane or a rigid boundary mechanical model tunnel. The choice of model tunnel has an impact on the imparted tunnel boundary displacements and resulting ground deformations, yet a thorough quantitative evaluation of these effects has not been conducted. This paper aims to address this by contrasting plane-strain centrifuge test results from experiments using a flexible membrane model tunnel with those from a newly developed eccentric rigid boundary mechanical model tunnel. A quantitative assessment of surface and subsurface settlement trough characteristics as well as soil shear and volumetric response is provided. Results from numerical analyses using a hypoplastic constitutive model are also included, focusing on evaluating centrifuge spin-up effects and contrasting numerical outcomes with experimental data relating to settlement trough characteristics and soil shear/volumetric response. The outcomes of this paper should benefit future researchers considering which type of model tunnel to adopt when developing centrifuge tests related to 2D plane-strain tunnel modelling.