Tunnelling on urban areas: 3D numerical analysis of soil/structure interaction

Shallow tunnelling performed by TBM induces volume loss, mainly due to the conical shape of the machine and the consolidation of the injected grout. Ground movements induced on the surface are susceptible to cause damages to surrounding structures. To estimate these damages, it is not sufficient to apply the greenfield deformation, because the structure itself contributes to stiffen the soil. To accurately take into account this soil-structure interaction phenomenon, a three-dimensional numerical analysis is required. This paper presents a finite difference analysis performed with the software FLAC(3D) of TBM tunnelling under a concrete six-floor building. Tunnelling is simulated by lateral convergence of the tunnel walls.