Numerical simulation of soil deformation induced by tunnel construction with unified hardening model

The deformation of surrounding soils and ground surface settlement induced by tunnel construction can have adverse effects on the adjacent underground structures and buildings. In the numerical simulation of soil deformation due to tunnel construction, the selection of constitutive models for soils is crucial. The UH model was developed based on the unified hardening (UH) parameter, which has the advantage of clear conception, fewer parameters and strong practicability, and has served in several major projects. Based on the UH model which accounts for the nonlinear degradation of elastic shear stiffness at the small strain range, a series of coupled hydro-mechanical (HM) finite element analyses has been carried out for simulating the entire construction process of the Crossrail Tunnel at Hyde Park in London. Comparison between the numerical predictions and field monitoring data exhibits excellent agreement. The predicted features of the ground surface settlement and subsurface vertical and horizontal displacements due to the construction of the Crossrail tunnels are analyzed in detail. Finally, by comparing against the predicted results using the modified Cam-clay (MCC) model accounting for the small strain behaviour, the advantages of the UH model in describing the stress-strain response of heavily overconsolidated clays are further verified.