Effect of Tunnelling on Adjacent Building Foundations

Abstract

Tunnelling activities in urban areas are always associated with surface and subsurface ground subsidence, which may affect the stability of nearby structures and utilities. In cases, where these structures founded utilizing deep foundation systems, the ground subsidence associated with tunnelling must be cautiously considered because in most cases of shallow tunnelling conditions, the deep foundations may be located in the zones of influence of tunnelling activities. Also, the characteristics of ground-pile interaction play an important role in the stability of these structures.

The main objective of the present study is to numerically evaluate the nature of interaction between the employed tunnelling technology and the nearby structures founded on deep foundation systems using 3D finite element idealization. Three dimensional analysis is essential for more accurate prediction and gives more flexibility in handling complex tunnelling process and soil condition.The analyses described in this thesis were performed using finite element program ABAQUS 6.11. The soil convergence around the tunnel opening is modelled using a non-associated Mohr Coulomb failure criterion. The shield, tunnel lining elements, piles elements, and pile caps elements are characterized as elastic elements with different elastic properties to account for the different stiffness of the these elements. On the other hand, the main elements of the interaction such as; ground continuum, the piles, the pile caps, the precast lining segments, the tail skin grouting, the developed gap around TBM due to machine overcutting, and the TBM shield are modelled using prismatic solid element.