Numerical back-analyses of greenfield settlement during tunnel boring

This paper examines the potential for two-dimensional (2D) and three-dimensional (3D) finite element (FE) analyses to calculate the ground displacement patterns observed at a greenfield site above two recently completed tunnels in Perth, Western Australia. The influence of a range of different factors on the shape of the tunnelling-induced settlement trough is examined using the Plaxis FE code and three soil constitutive models. It is shown that while model input parameters can be varied to produce calculations that are more comparable to field observations, there remain considerable errors associated with modelling of the tunnelling procedure by the imposition of volumetric contractions at the tunnel location.