A STRUCTURE'S INFLUENCE ON TUNNELLING-INDUCED GROUND MOVEMENTS.

The influence of tunnelling on buildings has become an important issue. The problem is an interactive one; not only do tunnelling settlements affect existing structures, but existing structures affect tunnel-induced soil movements. In this paper the results of a parametric study of the influence of an existing structure on the ground movements due to tunnelling are presented. The width of the structure, its bending and axial stiffness, its position relative to the tunnel and the depth of the tunnel are considered. The interaction is shown by reference to commonly-used building damage parameters, namely deflection ratio and maximum horizontal strain. By introducing relative stiffness parameters which combine the bending and axial stiffness of the structure with its width and the stiffness of the soil, design curves are established. These give a guide as to the likely modification to the greenfield settlement trough caused by a surface structure. They can be used to give initial estimates of likely building damage. (A)