The Influence of Building weight on Tunnelling-Induced Ground and Building Deformation

Abstract

In urban areas, the ground movements induced by tunnelling can distort and damage overlying buildings. Potts and Addenbrooke (1997) presented new design charts to assist in the assessment of building damage in response to tunnelling. The charts were based on the results of two-dimensional plane-strain finite element analyses considering variations in the bending and axial stiffness of a building relative to the soil stiffness, the building's width, its position relative to the tunnel axis, and the tunnel depth. In all cases, weightless elastic beams represented the building. This paper presents the results of analyses that additionally consider building weight in order to investigate its influence on the tunnelling-induced deformation of a structure. The mechanisms that control this interaction problem are investigated. It is demonstrated how the application of building load changes the stress regime in the ground and how this stress change alters tunnelling induced ground and building deformation. The results of a parametric study are used to quantify the effect of a building's self weight. This paper shows that the trend in deflection ratio and horizontal strain with building stiffness is very similar for a wide range of loads investigated. Following the approach of Potts and Addenbrooke (1997), the deformation values are then compared with the greenfield cases to give modification factors. The results reveal an increase in these factors with weight. On the other hand, when plotted against relative stiffness the results are shown to be close to the 'weightless' design curves provided by Potts and Addenbrooke (1997).