Modelling of surface settlements induced by a non-uniformly deforming tunnel

The design of tunnels requires the proper prediction of surface settlements for estimating the potential impact on adjacent structures. In computational methods, accurate prediction of the tunnelling-induced surface settlements should consider the features of the non-linear elastic soil behaviour, the tunnel deformation boundary condition and the tunnelling details. In this paper the tunnel-deforming mechanism is modelled by an analytical approach to account for the three different tunnel-deforming components, i.e. ground loss, ovalization and vertical translation. The deformation around the tunnel profile was shown to be highly non-uniform. Such a tunnel deformation model was then integrated into the numerical analysis to investigate how the influences affect the predicted surface settlement profile. The capacity and applicability of the proposed procedure were explored by means of a parametric study. Results indicate that a realistic tunnel-deforming pattern combined with a soil model that can take account of stiffness decay at small strains can lead to a more accurate prediction of tunnelling-induced settlement profiles.